[Title of Invention]

USER EQUIPMENTS AND COMMUNICATION METHODS

[Technical Field]

[0001] The present disclosure relates to a user equipment, and a communication method.

[Background Art]

[0002] At present, as a radio access system and a radio network technology aimed for the fifth generation cellular system, technical investigation and standard development are being conducted, as extended standards of Long Term Evolution (LTE), on LTE-Advanced Pro (LTE-A Pro) and New Radio technology (NR) in The Third Generation Partnership Project (3 GPP).

[0003] In the fifth generation cellular system, three services of enhanced Mobile BroadBand (eMBB) to achieve high-speed and large-volume transmission, UltraReliable and Low Latency Communication (URLLC) to achieve low-latency and high- reliability communication, and massive Machine Type Communication (mMTC) to allow connection of a large number of machine type devices such as Internet of Things (loT) have been demanded as assumed scenarios.

[0004] For example, wireless communication devices may communicate with one or more devices for multiple service types. For some device types, a lower complexity would be required such as to reduce the Rx/Tx antennas and/or the RF/Baseband bandwidth to reduce the UE complexity and the UE cost. However, given the reduced antennas and/or the bandwidth, the flexibility and/or the efficiency of the whole system would be limited. As illustrated by this discussion, systems and methods according to the present invention, supporting how to apply random access parameters and how to select random access resources for random access procedure, may improve the communication flexibility and/or efficiency and be beneficial.

[Brief Description of the Drawings] [0005] Figure 1 is a block diagram illustrating one configuration of one or more base stations and one or more user equipments (UEs) in which systems and methods for random access may be implemented;

[0006] Figure 2 is a diagram illustrating one example 200 of a resource grid;

[0007] Figure 3 is a diagram illustrating one example 300 of common resource block grid, carrier configuration and BWP configuration by a UE 102 and a base station 160;

[0008] Figure 4 is a diagram illustrating one 400 example of CORESET configuration in a BWP by a UE 102 and a base station 160;

[0009] Figure 5 is a diagram illustrating one example 500 of SS/PBCH block transmission;

[0010] Figure 6 is a diagram illustrating some examples 600-1 and 600-2 of mapping SS/PBCH block indexes to PRACH occasions;

[0011] Figure 7 is a diagram illustrating one 700 example of 4-step random access procedure;

[0012] Figure 8 is a diagram illustrating one 800 example of fields included in an RAR UL grant;

[0013] Figure 9 is a diagram illustrating some examples 900-1 and 900-2 of 2-step random access procedure;

[0014] Figure 10 is a flow diagram illustrating one implementation of a method 1000 for applying RRC parameter(s) for random access initialization by a UE 102;

[0015] Figure 11 is a flow diagram illustrating one implementation of a method 1100 for selection of 4-step RA type and 2-step RA type by a UE 102;

[0016] Figure 12 is a flow diagram illustrating one implementation of a method 1200 for determining preambles configured by different cell specific random access configurations by a UE 102;

[0017] Figure 13 is a diagram illustrating some examples 1300-1 and 1300-2 for determining preambles configured by different cell specific random access configurations by a UE 102;

[0018] Figure 14 illustrates various components that may be utilized in a UE;

[0019] Figure 15 illustrates various components that may be utilized in a base station; [Description of Embodiments]

[0020] A communication method by a user equipment (UE) is described. The method includes receiving, from a base station, from a base station, system information including a first cell specific random access configuration and a second cell specific random access configuration; and applying the second parameter for PRACH transmission in a case that the second cell specific random access configuration includes a second parameter; and applying a first parameter included in the first cell specific random access configuration for PRACH transmission in a case that the second cell specific random access configuration does not include the second parameter.

[0021] A communication method by a base station is described. The method includes transmitting, to a user equipment (UE), system information including a first RRC parameter, including a first cell specific random access configuration and a second cell specific random access configuration; and applying the second parameter for PRACH reception in a case that the second cell specific random access configuration includes a second parameter; and applying a first parameter included in the first cell specific random access configuration for PRACH reception in a case that the second cell specific random access configuration does not include the second parameter.

[0022] A user equipment (UE) is described. The UE includes reception circuitry configured to receive, from a base station, system information including a first cell specific random access, configuration and a second cell specific random access configuration; and control circuitry configured to, in a case that the second cell specific random access configuration includes a second parameter, apply the second parameter for PRACH transmission, in a case that the second cell specific random access configuration does not include the second parameter, apply a first parameter included in the first cell specific random access configuration for PRACH transmission.

[0023] A base station is described. The base station includes transmission circuitry configured to transmit, to a user equipment (UE), system information including a first cell specific random access configuration and a second cell specific random access configuration; and control circuitry configured to, in a case that the second cell specific random access configuration includes a second parameter, apply the second parameter for PRACH reception, in a case that the second cell specific random access configuration does not include the second parameter, apply a first parameter included in the first cell specific random access configuration for PRACH reception.

[0024] 3GPP Long Term Evolution (LTE) is the name given to a project to improve the Universal Mobile Telecommunications System (UMTS) mobile phone or device standard to cope with future requirements. In one aspect, UMTS has been modified to provide support and specification for the Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN). 3GPP NR (New Radio) is the name given to a project to improve the LTE mobile phone or device standard to cope with future requirements. In one aspect, LTE has been modified to provide support and specification (TS 38.331, 38.321, 38.300, 37.300, 38.211, 38.212, 38.213, 38.214, etc) for the New Radio Access (NR) and Next generation - Radio Access Network (NG-RAN).

[0025] At least some aspects of the systems and methods disclosed herein may be described in relation to the 3 GPP LTE, LTE-Advanced (LTE- A), LTE-Advanced Pro, New Radio Access (NR), and other 3G/4G/5G standards (e.g., 3GPP Releases 8, 9, 10, 11, 12, 13, 14, 15, and/or 16, and/or Narrow Band-Internet of Things (NB-IoT)). However, the scope of the present disclosure should not be limited in this regard. At least some aspects of the systems and methods disclosed herein may be utilized in other types of wireless communication systems.

[0026] A wireless communication device may be an electronic device used to communicate voice and/or data to a base station, which in turn may communicate with a network of devices (e.g., public switched telephone network (PSTN), the Internet, etc.). In describing systems and methods herein, a wireless communication device may alternatively be referred to as a mobile station, a UE (User Equipment), an access terminal, a subscriber station, a mobile terminal, a remote station, a user terminal, a terminal, a subscriber unit, a mobile device, a relay node, etc. Examples of wireless communication devices include cellular phones, smart phones, personal digital assistants (PDAs), laptop computers, netbooks, e-readers, wireless modems, industrial wireless sensors, video surveillance, wearables, etc. In 3GPP specifications, a wireless communication device is typically referred to as a UE. However, as the scope of the present disclosure should not be limited to the 3GPP standards, the terms “UE” and “wireless communication device” may be used interchangeably herein to mean the more general term “wireless communication device.” [0027] In 3GPP specifications, a base station is typically referred to as a gNB, a Node B, an eNB, a home enhanced or evolved Node B (HeNB) or some other similar terminology. As the scope of the disclosure should not be limited to 3GPP standards, the terms “base station,”, “gNB”, “Node B,” “eNB,” and “HeNB” may be used interchangeably herein to mean the more general term “base station.” Furthermore, one example of a “base station” is an access point. An access point may be an electronic device that provides access to a network (e.g., Local Area Network (LAN), the Internet, etc.) for wireless communication devices. The term “communication device” may be used to denote both a wireless communication device and/or a base station.

[0028] It should be noted that as used herein, a “cell” may be any communication channel that is specified by standardization or regulatory bodies to be used for International Mobile Telecommunications-Advanced (IMT-Advanced), IMT-2020 (5G) and all of it or a subset of it may be adopted by 3GPP as licensed bands (e.g., frequency bands) to be used for communication between a base station and a UE. It should also be noted that in NR, NG-RAN, E-UTRA and E-UTRAN overall description, as used herein, a “cell” may be defined as “combination of downlink and optionally uplink resources.” The linking between the carrier frequency of the downlink resources and the carrier frequency of the uplink resources may be indicated in the system information transmitted on the downlink resources.

[0029] “Configured cells” are those cells of which the UE is aware and is allowed by a base station to transmit or receive information. “Configured cell(s)” may be serving cell(s). The UE may receive system information and perform the required measurements on configured cells. “Configured cell(s)” for a radio connection may consist of a primary cell and/or no, one, or more secondary cell(s). “Activated cells” are those configured cells on which the UE is transmitting and receiving. That is, activated cells are those cells for which the UE monitors the physical downlink control channel (PDCCH) and in the case of a downlink transmission, those cells for which the UE decodes a physical downlink shared channel (PDSCH). “Deactivated cells” are those configured cells that the UE is not monitoring the transmission PDCCH. It should be noted that a “cell” may be described in terms of differing dimensions. For example, a “cell” may have temporal, spatial (e.g., geographical) and frequency characteristics.

[0030] The base stations may be connected by the NG interface to the 5G - core network (5G-CN). 5G-CN may be called as to NextGen core (NGC), or 5G core (5GC). The base stations may also be connected by the S1 interface to the evolved packet core (EPC). For instance, the base stations may be connected to a NextGen (NG) mobility management function by the NG-2 interface and to the NG core User Plane (UP) functions by the NG-3 interface. The NG interface supports a many-to-many relation between NG mobility management functions, NG core UP functions and the base stations. The NG-2 interface is the NG interface for the control plane and the NG-3 interface is the NG interface for the user plane. For instance, for EPC connection, the base stations may be connected to a mobility management entity (MME) by the S1 - MME interface and to the serving gateway (S-GW) by the S1-U interface. The S1 interface supports a many-to-many relation between MMEs, serving gateways and the base stations. The S1 -MME interface is the S1 interface for the control plane and the Sl-U interface is the S1 interface for the user plane. The Uu interface is a radio interface between the UE and the base station for the radio protocol.

[0031] The radio protocol architecture may include the user plane and the control plane. The user plane protocol stack may include packet data convergence protocol (PDCP), radio link control (RLC), medium access control (MAC) and physical (PHY) layers. A DRB (Data Radio Bearer) is a radio bearer that carries user data (as opposed to control plane signaling). For example, a DRB may be mapped to the user plane protocol stack. The PDCP, RLC, MAC and PHY sublayers (terminated at the base station 460a on the network) may perform functions (e.g., header compression, ciphering, scheduling, ARQ and HARQ) for the user plane. PDCP entities are located in the PDCP sublayer. RLC entities may be located in the RLC sublayer. MAC entities may be located in the MAC sublayer. The PHY entities may be located in the PHY sublayer.

[0032] The control plane may include a control plane protocol stack. The PDCP sublayer (terminated in base station on the network side) may perform functions (e.g., ciphering and integrity protection) for the control plane. The RLC and MAC sublayers (terminated in base station on the network side) may perform the same functions as for the user plane. The Radio Resource Control (RRC) (terminated in base station on the network side) may perform the following functions. The RRC may perform broadcast functions, paging, RRC connection management, radio bearer (RB) control, mobility functions, UE measurement reporting and control. The Non-Access Stratum (NAS) control protocol (terminated in MME on the network side) may perform, among other things, evolved packet system (EPS) bearer management, authentication, evolved packet system connection management (ECM) -IDLE mobility handling, paging origination in ECM-IDLE and security control.

[0033] Signaling Radio Bearers (SRBs) are Radio Bearers (RB) that may be used only for the transmission of RRC and NAS messages. Three SRBs may be defined. SRB0 may be used for RRC messages using the common control channel (CCCH) logical channel. SRB1 may be used for RRC messages (which may include a piggybacked NAS message) as well as for NAS messages prior to the establishment of SRB2, all using the dedicated control channel (DCCH) logical channel. SRB2 may be used for RRC messages which include logged measurement information as well as for NAS messages, all using the DCCH logical channel. SRB2 has a lower-priority than SRB1 and may be configured by a network (e.g., base station) after security activation. A broadcast control channel (BCCH) logical channel may be used for broadcasting system information. Some of BCCH logical channel may convey system information which may be sent from the network to the UE via BCH (Broadcast Channel) transport channel. BCH may be sent on a physical broadcast channel (PBCH). Some of BCCH logical channel may convey system information which may be sent from the network to the UE via DL-SCH (Downlink Shared Channel) transport channel. Paging may be provided by using paging control channel (PCCH) logical channel.

[0034] For example, the DL-DCCH logical channel may be used (but not limited to) for a RRC reconfiguration message, a RRC reestablishment message, a RRC release, a UE Capability Enquiry message, a DL Information Transfer message or a Security Mode Command message. UL-DCCH logical channel may be used (but not limited to) for a measurement report message, a RRC Reconfiguration Complete message, a RRC Reestablishment Complete message, a RRC Setup Complete message, a Security Mode Complete message, a Security Mode Failure message, a UE Capability Information, message, a UL Handover Preparation Transfer message, a UL Information Transfer message, a Counter Check Response message, a UE Information Response message, a Proximity Indication message, a RN (Relay Node) Reconfiguration Complete message, an MBMS Counting Response message, an inter Frequency RSTD Measurement Indication message, a UE Assistance Information message, an In-device Coexistence Indication message, an MBMS Interest Indication message, an SCG Failure Information message. DL-CCCH logical channel may be used (but not limited to) for a RRC Connection Reestablishment message, a RRC Reestablishment Reject message, a RRC Reject message, or a RRC Setup message. UL-CCCH logical channel may be used (but not limited to) for a RRC Reestablishment Request message, or a RRC Setup Request message.

[0035] System information may be divided into the MasterlnformationBlock (MIB) and a number of SystemlnformationBlocks (SIBs).

[0036] The UE may receive one or more RRC messages from the base station to obtain RRC configurations or parameters. The RRC layer of the UE may configure RRC layer and/or lower layers (e.g., PHY layer, MAC layer, RLC layer, PDCP layer) of the UE according to the RRC configurations or parameters which may be configured by the RRC messages, broadcasted system information, and so on. The base station may transmit one or more RRC messages to the UE to cause the UE to configure RRC layer and/or lower layers of the UE according to the RRC configurations or parameters which may be configured by the RRC messages, broadcasted system information, and so on.

[0037] When carrier aggregation is configured, the UE may have one RRC connection with the network. One radio interface may provide carrier aggregation. During RRC establishment, re-establishment and handover, one serving cell may provide Non-Access Stratum (NAS) mobility information (e.g., a tracking area identity (TAI)). During RRC re-establishment and handover, one serving cell may provide a security input. This cell may be referred to as the primary cell (PCell). In the downlink, the component carrier corresponding to the PCell may be the downlink primary component carrier (DL PCC), while in the uplink it may be the uplink primary component carrier (UL PCC). In the present disclosure, the terms “component carrier” and “carrier” can be interchanged with each other.

[0038] Depending on UE capabilities, one or more SCells may be configured to form together with the PCell a set of serving cells. In the downlink, the component carrier corresponding to an SCell may be a downlink secondary component carrier (DL SCC), while in the uplink it may be an uplink secondary component carrier (UL SCC). [0039] The configured set of serving cells for the UE, therefore, may consist of one PCell and one or more SCells. For each SCell, the usage of uplink resources by the UE (in addition to the downlink resources) may be configurable. The number of DL SCCs configured may be larger than or equal to the number of UL SCCs and no SCell may be configured for usage of uplink resources only.

[0040] From a UE viewpoint, each uplink resource may belong to one serving cell. The number of serving cells that may be configured depends on the aggregation capability of the UE. The PCell may only be changed using a handover procedure (e.g., with a security key change and a random access procedure). A PCell may be used for transmission of the PUCCH. A primary secondary cell (PSCell) may also be used for transmission of the PUCCH. The PSCell may be referred to as a primary SCG cell or SpCell of a secondary cell group. The PCell or PSCell may not be de-activated. Reestablishment may be triggered when the PCell experiences radio link failure (RLF), not when the SCells experience RLF. Furthermore, NAS information may be taken from the PCell.

[0041] The reconfiguration, addition and removal of SCells may be performed by RRC. At handover or reconfiguration with sync, Radio Resource Control (RRC) layer may also add, remove or reconfigure SCells for usage with a target PCell. When adding a new SCell, dedicated RRC signaling may be used for sending all required system information of the SCell (e.g., while in connected mode, UEs need not acquire broadcasted system information directly from the SCells).

[0042] The systems and methods described herein may enhance the efficient use of radio resources in Carrier aggregation (CA) operation. Carrier aggregation refers to the concurrent utilization of more than one component carrier (CC). In carrier aggregation, more than one cell may be aggregated to a UE. In one example, carrier aggregation may be used to increase the effective bandwidth available to a UE. In traditional carrier aggregation, a single base station is assumed to provide multiple serving cells for a UE. Even in scenarios where two or more cells may be aggregated (e.g., a macro cell aggregated with remote radio head (RRH) cells) the cells may be controlled (e.g., scheduled) by a single base station. However, in a small cell deployment scenario, each node (e.g., base station, RRH, etc.) may have its own independent scheduler. To maximize the efficiency of radio resources utilization of both nodes, a UE may connect to two or more nodes that have different schedulers. The systems and methods described herein may enhance the efficient use of radio resources in dual connectivity operation. A UE may be configured multiple groups of serving cells, where each group may have carrier aggregation operation (e.g., if the group includes more than one serving cell). [0043] In Dual Connectivity (DC) the UE may be required to be capable of UL-CA with simultaneous PUCCH/PUCCH and PUCCH/PUSCH transmissions across cell- groups (CGs). In a small cell deployment scenario, each node (e.g., eNB, RRH, etc.) may have its own independent scheduler. To maximize the efficiency of radio resources utilization of both nodes, a UE may connect to two or more nodes that have different schedulers. A UE may be configured multiple groups of serving cells, where each group may have carrier aggregation operation (e.g., if the group includes more than one serving cell). A UE in RRC CONNECTED may be configured with Dual Connectivity or MR-DC, when configured with a Master and a Secondary Cell Group. A Cell Group (CG) may be a subset of the serving cells of a UE, configured with Dual Connectivity (DC) or MR-DC, i.e. a Master Cell Group (MCG) or a Secondary Cell Group (SCG). The Master Cell Group may be a group of serving cells of a UE comprising of the PCell and zero or more secondary cells. The Secondary Cell Group (SCG) may be a group of secondary cells of a UE, configured with DC or MR-DC, comprising of the PSCell and zero or more other secondary cells. A Primary Secondary Cell (PSCell) may be the SCG cell in which the UE is instructed to perform random access when performing the SCG change procedure. “PSCell” may be also called as a Primary SCG Cell. In Dual Connectivity or MR-DC, two MAC entities may be configured in the UE: one for the MCG and one for the SCG. Each MAC entity may be configured by RRC with a serving cell supporting PUCCH transmission and contention based Random Access. In a MAC layer, the term Special Cell (SpCell) may refer to such cell, whereas the term SCell may refer to other serving cells. The term SpCell either may refer to the PCell of the MCG or the PSCell of the SCG depending on if the MAC entity is associated to the MCG or the SCG, respectively. A Timing Advance Group (TAG) containing the SpCell of a MAC entity may be referred to as primary TAG (pTAG), whereas the term secondary TAG (sTAG) refers to other TAGs.

[0044] DC may be further enhanced to support Multi-RAT Dual Connectivity (MR- DC). MR-DC may be a generalization of the Intra-E-UTRA Dual Connectivity (DC) described in 36.300, where a multiple Rx/Tx UE may be configured to utilize resources provided by two different nodes connected via non-ideal backhaul, one providing E- UTRA access and the other one providing NR access. One node acts as a Mater Node (MN) and the other as a Secondary Node (SN). The MN and SN are connected via a network interface and at least the MN is connected to the core network. In DC, a PSCell may be a primary secondary cell. In EN-DC, a PSCell may be a primary SCG cell or SpCell of a secondary cell group.

[0045] E-UTRAN may support MR-DC via E-UTRA-NR Dual Connectivity (EN- DC), in which a UE is connected to one eNB that acts as a MN and one en-gNB that acts as a SN. The en-gNB is a node providing NR user plane and control plane protocol terminations towards the UE and acting as Secondary Node in EN-DC. The eNB is connected to the EPC via the S1 interface and to the en-gNB via the X2 interface. The en-gNB might also be connected to the EPC via the Sl-U interface and other en-gNBs via the X2-U interface.

[0046] A timer is running once it is started, until it is stopped or until it expires; otherwise it is not running. A timer can be started if it is not running or restarted if it is running. A Timer may be always started or restarted from its initial value.

[0047] For NR, a technology of aggregating NR carriers may be studied. Both lower layer aggregation like Carrier Aggregation (CA) for LTE and upper layer aggregation like DC are investigated. From layer 2/3 point of view, aggregation of carriers with different numerologies may be supported in NR.

[0048] The main services and functions of the RRC sublayer may include the following:

- Broadcast of System Information related to Access Stratum (AS) and Non Access Stratum (NAS);

- Paging initiated by CN or RAN;

- Establishment, maintenance and release of an RRC connection between the UE and NR RAN including:

- Addition, modification and release of carrier aggregation;

- Addition, modification and release of Dual Connectivity in NR or between LTE and NR;

- Security functions including key management;

- Establishment, configuration, maintenance and release of signaling radio bearers and data radio bearers;

- Mobility functions including:

- Handover;

- UE cell selection and reselection and control of cell selection and reselection;

- Context transfer at handover. - QoS management functions;

- UE measurement reporting and control of the reporting;

- NAS message transfer to/from NAS from/to UE.

[0049] Each MAC entity of a UE may be configured by RRC with a Discontinuous Reception (DRX) functionality that controls the UE's PDCCH monitoring activity for the MAC entity's C-RNTI (Radio Network Temporary Identifier), CS-RNTI, INT- RNTI, SFI-RNTI, SP-CSI-RNTI, TPC-PUCCH-RNTI, TPC-PUSCH-RNTI, and TPC- SRS-RNTI. For scheduling at cell level, the following identities are used:

C (Cell) -RNTI: unique UE identification used as an identifier of the RRC Connection and for scheduling;

CS (Configured Scheduling) -RNTI: unique UE identification used for Semi-Persistent Scheduling in the downlink;

INT-RNTI: identification of pre-emption in the downlink;

P-RNTI: identification of Paging and System Information change notification in the downlink;

SI-RNTI: identification of Broadcast and System Information in the downlink;

SP-CSI-RNTI: unique UE identification used for semi-persistent CSI reporting on PUSCH;

CI-RNTI: Cancellation Indication RNTI for Uplink.

For power and slot format control, the following identities are used:

SFI-RNTI: identification of slot format;

TPC-PUCCH-RNTI: unique UE identification to control the power of PUCCH;

TPC-PUSCH-RNTI: unique UE identification to control the power of PUSCH;

TPC-SRS-RNTI: unique UE identification to control the power of SRS;

During the random access procedure, the following identities are also used:

RA-RNTI: identification of the Random Access Response in the downlink;

Temporary C-RNTI: UE identification temporarily used for scheduling during the random access procedure; Random value for contention resolution: UE identification temporarily used for contention resolution purposes during the random access procedure.

For NR connected to 5GC, the following UE identities are used at NG-RAN level: I-RNTI: used to identify the UE context in RRC INACTIVE.

[0050] The size of various fields in the time domain is expressed in time units The constant where

[0051] Multiple OFDM numerologies are supported as given by Table 4.2-1 of [TS 38.211 ] where μ and the cyclic prefix for a bandwidth part are obtained from the higher- layer parameter subcarrierSpacing and cyclicPrefix, respectively.

[0052] The size of various fields in the time domain may be expressed as a number of time units T _c =1/(15000*2048) seconds. Downlink and uplink transmissions are organized into frames with duration, each consisting of ten subframes of duration. The number of consecutive OFDM symbols per subframe is . Each frame is divided into two equally-sized half-frames of five subframes each with half-frame 0 consisting of subframes 0 - 4 and half-frame 1 consisting of subframes 5 - 9.

[0053] For subcarrier spacing (SCS) configuration μ, slots are numbered in increasing order within a subframe and in increasing order within a frame. is the number of slots per subframe for subcarrier spacing configuration μ. There are consecutive OFDM symbols in a slot where depends on the cyclic prefix as given by Tables 4.3.2-1 and 4.3.2-2 of [TS 38.211], The start of slot in a subframe is aligned in time with the start of

OFDM symbol in the same subframe. Subcarrier spacing refers to a spacing (or frequency bandwidth) between two consecutive subcarrier in the frequency domain. For example, the subcarrier spacing can be set to 15kHz (i.e. μ=0), 30kHz (i.e. μ=1), 60kHz (i.e. μ=2), 120kHz (i.e. μ-3), or 240kHz (i.e. μ=4). A resource block is defined as a number of consecutive subcarriers (e.g. 12) in the frequency domain. For a carrier with different frequency, the applicable subcarrier may be different. For example, for a carrier in a frequency rang 1, a subcarrier spacing only among a set of {15kHz, 30kHz, 60kHz} is applicable. For a carrier in a frequency rang 2, a subcarrier spacing only among a set of {60kHz, 120kHz, 240kHz} is applicable. The base station may not configure an inapplicable subcarrier spacing for a carrier.

[0054] OFDM symbols in a slot can be classified as 'downlink', 'flexible', or 'uplink'. Signaling of slot formats is described in subclause 11.1 of [TS 38.213].

[0055] In a slot in a downlink frame, the UE may assume that downlink transmissions only occur in 'downlink' or 'flexible' symbols. In a slot in an uplink frame, the UE may only transmit in 'uplink' or 'flexible' symbols.

[0056] Various examples of the systems and methods disclosed herein are now described with reference to the Figures, where like reference numbers may indicate functionally similar elements. The systems and methods as generally described and illustrated in the Figures herein could be arranged and designed in a wide variety of different implementations. Thus, the following more detailed description of several implementations, as represented in the Figures, is not intended to limit scope, as claimed, but is merely representative of the systems and methods.

[0057] Figure 1 is a block diagram illustrating one configuration of one or more base stations 160 (e.g., eNB, gNB) and one or more user equipments (UEs) 102 in which systems and methods for PUCCH transmission with or without frequency hopping may be implemented. The one or more UEs 102 may communicate with one or more base stations 160 using one or more antennas 122a-n. For example, a UE 102 transmits electromagnetic signals to the base station 160 and receives electromagnetic signals from the base station 160 using the one or more antennas 122a-n. The base station 160 communicates with the UE 102 using one or more antennas 180a-n.

[0058] It should be noted that in some configurations, one or more of the UEs 102 described herein may be implemented in a single device. For example, multiple UEs 102 may be combined into a single device in some implementations. Additionally or alternatively, in some configurations, one or more of the base stations 160 described herein may be implemented in a single device. For example, multiple base stations 160 may be combined into a single device in some implementations. In the context of Figure 1, for instance, a single device may include one or more UEs 102 in accordance with the systems and methods described herein. Additionally or alternatively, one or more base stations 160 in accordance with the systems and methods described herein may be implemented as a single device or multiple devices.

[0059] The UE 102 and the base station 160 may use one or more channels 119, 121 to communicate with each other. For example, a UE 102 may transmit information or data to the base station 160 using one or more uplink (UL) channels 121 and signals. Examples of uplink channels 121 include a physical uplink control channel (PUCCH) and a physical uplink shared channel (PUSCH), etc. Examples of uplink signals include a demodulation reference signal (DMRS) and a sounding reference signal (SRS), etc. The one or more base stations 160 may also transmit information or data to the one or more UEs 102 using one or more downlink (DL) channels 119 and signals, for instance. Examples of downlink channels 119 include a PDCCH, a PDSCH, etc. A PDCCH can be used to schedule DL transmissions on PDSCH and UL transmissions on PUSCH, where the Downlink Control Information (DCI) on PDCCH includes downlink assignment and uplink scheduling grants. The PDCCH is used for transmitting Downlink Control Information (DCI) in a case of downlink radio communication (radio communication from the base station to the UE). Here, one or more DCIs (may be referred to as DCI formats) are defined for transmission of downlink control information. Information bits are mapped to one or more fields defined in a DCI format. Examples of downlink signals include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a cell-specific reference signal (CRS), a nonzero power channel state information reference signal (NZP CSI-RS), and a zero power channel state information reference signal (ZP CSI-RS), etc. Other kinds of channels or signals may be used.

[0060] Each of the one or more UEs 102 may include one or more transceivers 118, one or more demodulators 114, one or more decoders 108, one or more encoders 150, one or more modulators 154, one or more data buffers 104 and one or more UE operations modules 124. For example, one or more reception and/or transmission paths may be implemented in the UE 102. For convenience, only a single transceiver 118, decoder 108, demodulator 114, encoder 150 and modulator 154 are illustrated in the UE 102, though multiple parallel elements (e.g., transceivers 118, decoders 108, demodulators 114, encoders 150 and modulators 154) may be implemented.

[0061] The transceiver 118 may include one or more receivers 120 and one or more transmitters 158. The one or more receivers 120 may receive signals (e.g., downlink channels, downlink signals) from the base station 160 using one or more antennas 122a-n. For example, the receiver 120 may receive and downconvert signals to produce one or more received signals 116. The one or more received signals 116 may be provided to a demodulator 114. The one or more transmitters 158 may transmit signals (e.g., uplink channels, uplink signals) to the base station 160 using one or more antennas 122a-n. For example, the one or more transmitters 158 may upconvert and transmit one or more modulated signals 156.

[0062] The demodulator 114 may demodulate the one or more received signals 116 to produce one or more demodulated signals 112. The one or more demodulated signals 112 may be provided to the decoder 108. The UE 102 may use the decoder 108 to decode signals. The decoder 108 may produce one or more decoded signals 106, 110. For example, a first UE-decoded signal 106 may comprise received payload data, which may be stored in a data buffer 104. A second UE-decoded signal 110 may comprise overhead data and/or control data. For example, the second UE-decoded signal 110 may provide data that may be used by the UE operations module 124 to perform one or more operations.

[0063] As used herein, the term “module” may mean that a particular element or component may be implemented in hardware, software or a combination of hardware and software. However, it should be noted that any element denoted as a “module” herein may alternatively be implemented in hardware. For example, the UE operations module 124 may be implemented in hardware, software or a combination of both.

[0064] In general, the UE operations module 124 may enable the UE 102 to communicate with the one or more base stations 160. The UE operations module 124 may include a UE RRC information configuration module 126. The UE operations module 124 may include a UE random access (RA) control module 128. In some implementations, the UE operations module 124 may include physical (PHY) entities, Medium Access Control (MAC) entities, Radio Link Control (RLC) entities, packet data convergence protocol (PDCP) entities, and a Radio Resource Control (RRC) entity. For example, the UE RRC information configuration module 126 may process RRC parameter(s) included in random access configuration(s), initial UL BWP configuration, maximum bandwidth the UE can support, and cell specific PUCCH resource configuration(s). The UE RA control module (processing module) 128 may determine to select a SS/PBCH block for random access based on the measured RSRP value from the UE receiver 178. The UE RA control module 128 may determine a PRACH occasion and a preamble for PRACH transmission based on the processing output from the UE RRC information configuration module 126.

[0065] The UE RA control module 128 may determine to select a 4-step random access procedure or a 2-step random access procedure based on RRC parameters included in cell specific random access configurations. The UE RA control module 128 may determine how to apply random access parameter for different configurations for PRACH transmission.

[0066] The UE operations module 124 may provide information 148 to the one or more receivers 120. For example, the UE operations module 124 may inform the receiver(s) 120 when or when not to receive transmissions based on the Radio Resource Control (RRC) message (e.g., broadcasted system information, RRC reconfiguration message), MAC control element, and/or the DCI (Downlink Control Information). The UE operations module 124 may provide information 148, including the PDCCH monitoring occasions and DCI format size, to the one or more receivers 120. The UE operation module 124 may inform the receiver(s) 120 when or where to receive/monitor the PDCCH candidate for DCI formats with which DCI size.

[0067] The UE operations module 124 may provide information 138 to the demodulator 114. For example, the UE operations module 124 may inform the demodulator 114 of a modulation pattern anticipated for transmissions from the base station 160.

[0068] The UE operations module 124 may provide information 136 to the decoder 108. For example, the UE operations module 124 may inform the decoder 108 of an anticipated encoding for transmissions from the base station 160. For example, the UE operations module 124 may inform the decoder 108 of an an ticipated PDCCH candidate encoding with which DCI size for transmissions from the base station 160.

[0069] The UE operations module 124 may provide information 142 to the encoder 150. The information 142 may include data to be encoded and/or instructions for encoding. For example, the UE operations module 124 may instruct the encoder 150 to encode transmission data 146 and/or other information 142.

[0070] The encoder 150 may encode transmission data 146 and/or other information 142 provided by the UE operations module 124. For example, encoding the data 146 and/or other information 142 may involve error detection and/or correction coding, mapping data to space, time and/or frequency resources for transmission, multiplexing, etc. The encoder 150 may provide encoded data 152 to the modulator 154. [0071] The UE operations module 124 may provide information 144 to the modulator 154. For example, the UE operations module 124 may inform the modulator 154 of a modulation type (e.g., constellation mapping) to be used for transmissions to the base station 160. The modulator 154 may modulate the encoded data 152 to provide one or more modulated signals 156 to the one or more transmitters 158.

[0072] The UE operations module 124 may provide information 140 to the one or more transmitters 158. This information 140 may include instructions for the one or more transmitters 158. For example, the UE operations module 124 may instruct the one or more transmitters 158 when to transmit a signal to the base station 160. The one or more transmitters 158 may upconvert and transmit the modulated signal(s) 156 to one or more base stations 160.

[0073] The base station 160 may include one or more transceivers 176, one or more demodulators 172, one or more decoders 166, one or more encoders 109, one or more modulators 113, one or more data buffers 162 and one or more base station operations modules 182. For example, one or more reception and/or transmission paths may be implemented in a base station 160. For convenience, only a single transceiver 176, decoder 166, demodulator 172, encoder 109 and modulator 113 are illustrated in the base station 160, though multiple parallel elements (e.g., transceivers 176, decoders 166, demodulators 172, encoders 109 and modulators 113) may be implemented.

[0074] The transceiver 176 may include one or more receivers 178 and one or more transmitters 117. The one or more receivers 178 may receive signals (e.g., uplink channels, uplink signals) from the UE 102 using one or more antennas 180a-n. For example, the receiver 178 may receive and downconvert signals to produce one or more received signals 174. The one or more received signals 174 may be provided to a demodulator 172. The one or more transmitters 117 may transmit signals (e.g., downlink channels, downlink signals) to the UE 102 using one or more antennas 180a- n. For example, the one or more transmitters 117 may upconvert and transmit one or more modulated signals 115.

[0075] The demodulator 172 may demodulate the one or more received signals 174 to produce one or more demodulated signals 170. The one or more demodulated signals 170 may be provided to the decoder 166. The base station 160 may use the decoder 166 to decode signals. The decoder 166 may produce one or more decoded signals 164, 168. For example, a first base station-decoded signal 164 may comprise received pay load data, which may be stored in a data buffer 162. A second base station-decoded signal 168 may comprise overhead data and/or control data. For example, the second base station-decoded signal 168 may provide data (e.g., PUSCH transmission data) that may be used by the base station operations module 182 to perform one or more operations. [0076] In general, the base station operations module 182 may enable the base station 160 to communicate with the one or more UEs 102. The base station operations module 182 may include a base station RRC information configuration module 194. The base station operations module 182 may include a base station random access (RA) control module 196 (or a base station RA processing module 196). The base station operations module 182 may include PHY entities, MAC entities, RLC entities, PDCP entities, and an RRC entity.

[0077] The base station RA control module 196 may determine, for respective UE, when and where to transmit the preamble, the time and frequency resource of PRACH occasions and input the information to the base station RRC information configuration module 194. The base station RA control module 196 may generate a RAR UL grant to schedule a PUSCH with or without frequency hopping. The base station RA control module 196 may generate a DCI format to schedule a PDSCH. The base station RA control module 196 may generate cell specific random access configurations to a UE. The base station RA control module 196 may generate RRC parameters included in the cell specific random access configurations for a UE to determine one of 4-step random access procedure and 2-step random access procedure.

[0078] The base station operations module 182 may provide the benefit of performing PDCCH candidate search and monitoring efficiently. The base station operations module 182 may provide information 190 to the one or more receivers 178. For example, the base station operations module 182 may inform the receiver(s) 178 when or when not to receive transmissions based on the RRC message (e.g., broadcasted system information, RRC reconfiguration message), MAC control element, and/or the DCI (Downlink Control Information).

[0079] The base station operations module 182 may provide information 188 to the demodulator 172. For example, the base station operations module 182 may inform the demodulator 172 of a modulation pattern anticipated for transmissions from the UE(s) 102.

[0080] The base station operations module 182 may provide information 186 to the decoder 166. For example, the base station operations module 182 may inform the decoder 166 of an anticipated encoding for transmissions from the UE(s) 102.

[0081] The base station operations module 182 may provide information 101 to the encoder 109. The information 101 may include data to be encoded and/or instructions for encoding. For example, the base station operations module 182 may instruct the encoder 109 to encode transmission data 105 and/or other information 101.

[0082] In general, the base station operations module 182 may enable the base station 160 to communicate with one or more network nodes (e.g., a NG mobility management function, a NG core UP functions, a mobility management entity (MME), serving gateway (S-GW), gNBs). The base station operations module 182 may also generate a RRC reconfiguration message to be signaled to the UE 102.

[0083] The encoder 109 may encode transmission data 105 and/or other information 101 provided by the base station operations module 182. For example, encoding the data 105 and/or other information 101 may involve error detection and/or correction coding, mapping data to space, time and/or frequency resources for transmission, multiplexing, etc. The encoder 109 may provide encoded data 111 to the modulator 113. The transmission data 105 may include network data to be relayed to the UE 102.

[0084] The base station operations module 182 may provide information 103 to the modulator 113. This information 103 may include instructions for the modulator 113. For example, the base station operations module 182 may inform the modulator 113 of a modulation type (e.g., constellation mapping) to be used for transmissions to the UE(s) 102. The modulator 113 may modulate the encoded data 111 to provide one or more modulated signals 115 to the one or more transmitters 117.

[0085] The base station operations module 182 may provide information 192 to the one or more transmitters 117. This information 192 may include instructions for the one or more transmitters 117. For example, the base station operations module 182 may instruct the one or more transmitters 117 when to (or when not to) transmit a signal to the UE(s) 102. The base station operations module 182 may provide information 192, including the PDCCH monitoring occasions and DCI format size, to the one or more transmitters 117. The base station operation module 182 may inform the transmitter(s) 117 when or where to transmit the PDCCH candidate for DCI formats with which DCI size. The one or more transmitters 117 may upconvert and transmit the modulated signal(s) 115 to one or more UEs 102.

[0086] It should be noted that one or more of the elements or parts thereof included in the base station(s) 160 and UE(s) 102 may be implemented in hardware. For example, one or more of these elements or parts thereof may be implemented as a chip, circuitry or hardware components, etc. It should also be noted that one or more of the functions or methods described herein may be implemented in and/or performed using hardware. For example, one or more of the methods described herein may be implemented in and/or realized using a chipset, an application-specific integrated circuit (ASIC), a large-scale integrated circuit (LSI) or integrated circuit, etc.

[0087] Abase station may generate a RRC message including the one or more RRC parameters and transmit the RRC message to a UE. A UE may receive, from a base station, a RRC message including one or more RRC parameters. The term ‘RRC parameter(s)’ in the present disclosure may be alternatively referred to as ‘RRC information element(s)’. A RRC parameter may further include one or more RRC parameter(s). In the present disclosure, a RRC message may include system information, a RRC message may include one or more RRC parameters. A RRC message may be sent on a broadcast control channel (BCCH) logical channel, a common control channel (CCCH) logical channel or a dedicated control channel (DCCH) logical channel.

[0088] In the present disclosure, a description ‘a base station may configure a UE to’ may also imply/refer to ‘a base station may transmit, to a UE, an RRC message including one or more RRC parameters’. Additionally or alternatively, ‘RRC parameter configure a UE to’ may also refer to ‘a base station may transmit, to a UE, an RRC message including one or more RRC parameters’. Additionally or alternatively, ‘a UE is configured to’ may also refer to ‘a UE may receive, from a base station, an RRC message including one or more RRC parameters’.

[0089] Figure 2 is a diagram illustrating one example of a resource grid 200.

[0090] For each numerology and carrier, a resource grid of N _grid,x ^start,μ N _sc ^RB subcarriers and N _symb ^subframe ’ ^μ OFDM symbols is defined, starting at common resource block N _grid ^start ’ ^μ indicated by higher layer signaling. There is one set of resource grids per transmission direction (uplink or downlink) with the subscript x set to DL and UL for downlink and uplink, respectively. There is one resource grid for a given antenna port p, subcarrier spacing configuration μ, and the transmission direction (downlink or uplink). When there is no risk for confusion, the subscript x may be dropped.

[0091] In the Figure 2, the resource gird 200 includes the (202) subcarriers in the frequency domain and includes (204) symbols in the time domain. In the Figure 2, as an example for illustration, the subcarrier spacing configuration μ is set to 0. That is, in the Figure 2, the number of consecutive OFDM symbols (204) per subframe is equal to 14.

[0092] The carrier bandwidth for subcarrier spacing configuration μ is given by the higher-layer (RRC) parameter carrierBandwidth in the SCS-SpecificCarrier IE. The starting position for subcarrier spacing configuration μ is given by the higher-layer parameter offsetToCarrier in the SCS- SpecificCarrier IE. The frequency location of a subcarrier refers to the center frequency of that subcarrier.

[0093] In the Figure 2, for example, a value of offset is provided by the higher-layer parameter offsetToCarrier. That is, k = 12 X offset is the lowest usable subcarrier on this carrier.

[0094] Each element in the resource grid for antenna port p and subcarrier spacing configuration μ is called a resource element and is uniquely identified by (k, l) _p,μ where k is the index in the frequency domain and l refers to the symbols position in the time domain relative to same reference point. The resource element consists of one subcarrier during one OFDM symbol.

[0095] A resource block is defined as A _sc ^RB =12 consecutive subcarriers in the frequency domain. As shown in the Figure 2, a resource block 206 includes 12 consecutive subcarriers in the frequency domain. Resource block can be classified as common resource block (CRB) and physical resource block (PRB).

[0096] Common resource blocks are numbered from 0 and upwards in the frequency domain for subcarrier spacing configuration μ. The center of subcarrier 0 of common resource block with index 0 (i.e. CRB0) for subcarrier spacing configuration μ coincides with point A. The relation between the common resource block number in the frequency domain and resource element (k, I) for subcarrier spacing configuration μ is given by Formula (1) n _CRB ^μ =floor(k/N _sc ^RB )' where k is defined relative to the point A such that k=0 corresponds to the subcarrier centered around the point A. The function floor(A) hereinafter is to output a maximum integer not larger than the A. [0097] Point A refers to as a common reference point. Point A coincides with subcarrier 0 (i.e. k=0) of a CRB 0 for all subcarrier spacing. Point A can be obtained from a RRC parameter offsetToPointA or a RRC parameter absoluteFrequencyPointA. The RRC parameter offsetToPointA is used for a PCell downlink and represents the frequency offset between point A and the lowest subcarrier of the lowest resource block, which has the subcarrier spacing provided by a higher-layer parameter subCarrierSpacingCommon and overlaps with the SS/PBCH block used by the UE for initial cell selection, expressed in units of resource blocks assuming 15 kHz subcarrier spacing for frequency range (FR) 1 and 60 kHz subcarrier spacing for frequency range (FR2). FR1 corresponds to a frequency range between 410MHz and 7125MHz. FR2 corresponds to a frequency range between 24250MHz and 52600MHz. The RRC parameter absoluteFrequencyPointA is used for all cased other than the PCell case and represents the frequency-location of point A expressed as in ARFCN. The frequency location of point A can be the lowest subcarrier of the carrier bandwidth ( or the actual carrier). Additionally, point A may be located outside the carrier bandwidth ( or the actual carrier).

[0098] As above mentioned, the information element (IE) SCS-SpecificCarrier provides parameters determining the location and width of the carrier bandwidth or the actual carrier. That is, a carrier (or a carrier bandwidth, or an actual carrier) is determined (identified, or defined) at least by a RRC parameter offsetToCarrier, a RRC parameter subcarrierSpacing, and a RRC parameter carrierBandwidth in the SCS- SpecificCarrier IE.

[0099] The subcarrierSpacing indicates (or defines) a subcarrier spacing of the carrier. The offsetToCarrier indicates an offset in frequency domain between point A and a lowest usable subcarrier on this carrier in number of resource blocks (e.g. CRBs) using the subcarrier spacing defined for the carrier. The carrierBandwidth indicates width of this carrier in number of resource blocks (e.g. CRBs or PRBs) using the subcarrier spacing defined for the carrier. A carrier includes at most 275 resource blocks. [0100] Physical resource block for subcarrier spacing configuration μ are defined within a bandwidth part and numbered form 0 to N _BWP,i ^start ’ w ^μ here i is the number of the bandwidth part. The relation between the physical resource block in bandwidth part (BWP) i and the common resource block is given by Formula (2) is the common resource block where bandwidth part i starts relative to common resource block 0 (CRB0). When there is no risk for confusion the index μ may be dropped.

[0101] A BWP is a subset of contiguous common resource block for a given subcarrier spacing configuration μ on a given carrier. To be specific, a BWP can be identified (or defined) at least by a subcarrier spacing μ indicated by the RRC parameter subcarrierSpacing, a cyclic prefix determined by the RRC parameter cyclicPrefix, a frequency domain location, a bandwidth, an BWP index indicated by bwp-Id and so on. The locationAndBandwidth can be used to indicate the frequency domain location and bandwidth of a BWP. The value indicated by the locationAndBandwidth is interpreted as resource indicator value (RIV) corresponding to an offset (a starting resource block) RB _start and a length L _RB in terms of contiguously resource blocks. The offset RB _start is a number of CRBs between the lowest CRB of the carrier and the lowest CRB of the BWP. The N _BWP,i ^start ’ ^μ is given as Formula (3) N _BWP,i ^start ’ ^μ =O _carrier +RB _start . The value of O _carrier is provided by offsetTocarrier for the corresponding subcarrier spacing configuration μ.

[0102] A UE 102 configured to operation in BWPs of a serving cell, is configured by higher layers for the serving cell a set of at most four BWPs in the downlink for reception. At a given time, a single downlink BWP is active. The bases station 160 may not transmit, to the UE 102, PDSCH and/or PDCCH outside the active downlink BWP. A UE 102 configured to operation in BWPs of a serving cell, is configured by higher layers for the serving cell a set of at most four BWPs for transmission. At a given time, a single uplink BWP is active. The UE 102 may not transmit, to the base station 160, PUSCH or PUCCH outside the active BWP. The specific signaling (higher layers signaling) for BWP configurations are described later.

[0103] Figure 3 is a diagram illustrating one example 300 of common resource block grid, carrier configuration and BWP configuration by a UE 102 and a base station 160.

[0104] Point A 301 is a lowest subcarrier of a CRB0 for all subcarrier spacing configurations. The CRB grid 302 and the CRB grid 312 are corresponding to two different subcarrier spacing configurations. The CRB grid 302 is for subcarrier spacing configuration μ =0 (i.e. the subcarrier spacing with 15kHz). The CRB grid 312 is for subcarrier spacing configuration μ =1 (i.e. the subcarrier spacing with 30kHz).

[0105] One or more carriers are determined by respective SCS-SpecificCarrier IES, respectively. In the Figure 3, the carrier 304 uses the subcarrier spacing configuration μ=0. And the carrier 314 uses the subcarrier spacing configuration μ=1. The starting position of the carrier 304 is given based on the value of an offset 303 (i.e. O _carrier ) indicated by an offsetToCarrier in an SCS-SpecificCarrier IE. As shown in the Figure 3, for example, the offsetToCarrier indicates the value of the offset 303 as O _carrier =3. That is, the starting position of the carrier 304 corresponds to the CRB3 of the CRB grid 302 for subcarrier spacing configuration μ=0. In the meantime, the starting position of the carrier 314 is given based on the value of an offset 313 (i.e. O _carrier ) indicated by an offsetToCarrier in another SCS-SpecificCarrier IE. For example, the offsetToCarrier indicates the value of the offset 313 as O _carrier =1. That is, the starting position of the carrier 314 corresponds to the CRB 1 of the CRB grid 312 for subcarrier spacing configuration μ=1. A carrier using different subcarrier spacing configurations can occupy different frequency ranges.

[0106] As above-mentioned, a BWP is for a given subcarrier spacing configuration μ. One or more BWPs can be configured for a same subcarrier spacing configuration μ. For example, in the Figure 3, the BWP 306 is identified at least by the μ=0, a frequency domain location, a bandwidth (L _RB ), and an BWP index (index A). The first PRB (i.e. PRB0) of a BWP is determined at least by the subcarrier spacing of the BWP, an offset derived by the locationAndBandwidth and an offset indicated by the offsetToCarrier corresponding to the subcarrier spacing of the BWP. An offset 305 (RB _start ) is derived as 1 by the locationAndBandwidth. According to the Formulas (2) and (3), the PRB0 of BWP 306 corresponds to CRB 4 of the CRB grid 302, and the PRB1 of BWP 306 corresponds to CRB 5 of the CRB grid 302, and so on.

[0107] Additionally, in the Figure 3, the BWP 308 is identified at least by the μ=0, a frequency domain location, a bandwidth (L _RB ), and an BWP index (index B). For example, an offset 307 (RB _start ) is derived as 6 by the locationAndBandwidth. According to the Formulas (2) and (3), the PRB0 of BWP 308 corresponds to CRB 9 of the CRB grid 302, and the PRB1 of BWP 308 corresponds to CRB 10 of the CRB grid 302, and so on. [0108] Additionally, in the Figure 3, the BWP 316 is identified at least by the μ=1, a frequency domain location, a bandwidth (L _RB ), and an BWP index (index C). For example, an offset 315 ( RB _start ) is derived as 1 by the locationAndBandwidth. According to the Formulas (2) and (3), the PRB0 of BWP 316 corresponds to CRB 2 of the CRB grid 312, and the PRB1 of BWP 316 corresponds to CRB 3 of the CRB grid 312, and so on.

[0109] As shown in the Figure 3, a carrier with the defined subcarrier spacing locate in a corresponding CRB grid with the same subcarrier spacing. A BWP with the defined subcarrier spacing locate in a corresponding CRB grid with the same subcarrier spacing as well.

[0110] A base station may transmit a RRC message including one or more RRC parameters related to BWP configuration to a UE. A UE may receive the RRC message including one or more RRC parameters related to BWP configuration from a base station. For each cell, the base station may configure at least an initial DL BWP and one initial uplink bandwidth parts (initial UL BWP) to the UE. Furthermore, the base station may configure additional UL and DL BWPs to the UE for a cell.

[0111] A RRC parameters initialDownlinkBWP may indicate the initial downlink BWP (initial DL BWP) configuration for a serving cell (e.g., a SpCell and Scell). The base station may configure the RRC parameter locationAndBandwidth included in the initialDownlinkBWP so that the initial DL BWP contains the entire CORESET 0 of this serving cell in the frequency domain. The locationAndBandwidth may be used to indicate the frequency domain location and bandwidth of a BWP. A RRC parameters initialUplinkBWP may indicate the initial uplink BWP (initial UL BWP) configuration for a serving cell (e.g., a SpCell and Scell). The base station may transmit initialDownlinkBWP and/ or initialUplinkBWP which may be included in SIB1, RRC parameter ServingCellConfigCommon, or RRC parameter ServingCellConfig to the UE. [0112] SIB1, which is a cell-specific system information block (SystemlnformationBlock, SIB), may contain information relevant when evaluating if a UE is allowed to access a cell and define the scheduling of other system information. SIB1 may also contain radio resource configuration information that is common for all UEs and barring information applied to the unified access control. The RRC parameter ServingCellConfigCommon is used to configure cell specific parameters of a UE's serving cell. The RRC parameter ServingCellConfig is used to configure (add or modify) the UE with a serving cell, which may be the SpCell or an SCell of an MCS or SCG. The RRC parameter ServingCellConfig herein are mostly UE specific but partly also cell specific.

[0113] The base station may configure the UE with a RRC parameter BWP- Downlink and a RRC parameter BWP- Uplink. The RRC parameter BWP-Downlink can be used to configure an additional DL BWP. The RRC parameter BWP-Uplink can be used to configure an additional UL BWP. The base station may transmit the BWP- Downlink and the BWP-Uplink which may be included in RRC parameter ServingCellConfig to the UE.

[0114] If a UE is not configured (provided) initialDownlinkBWP from a base station, an initial DL BWP is defined by a location and number of contiguous physical resource blocks (PRBs), starting from a PRB with the lowest index and ending at a PRB with the highest index among PRBs of a CORESET for TypeO-PDCCH CSS set (i.e. CORESET 0), and a subcarrier spacing (SCS) and a cyclic prefix for PDCCH reception in the CORESET for TypeO-PDCCH CSS set. If a UE is configured (provided) initialDownlinkBWP from a base station, the initial DL BWP is provided by initialDownlinkBWP . If a UE is configured (provided) initialUplinkBWP from a base station, the initial UL BWP is provided by initialUplinkBWP.

[0115] The UE may be configured by the based station, at least one initial BWP and up to 4 additional BWP(s). One of the initial BWP and the configured additional BWP(s) may be activated as an active BWP. The UE may monitor DCI format, and/or receive PDSCH in the active DL BWP. The UE may not monitor DCI format, and/or receive PDSCH in a DL BWP other than the active DL BWP. The UE may transmit PUSCH and/or PUCCH in the active UL BWP. The UE may not transmit PUSCH and/or PUCCH in a BWP other than the active UL BWP.

[0116] As above-mentioned, a UE may monitor DCI format in the active DL BWP. To be more specific, a UE may monitor a set of PDCCH candidates in one or more CORESETs on the active DL BWP on each activated serving cell configured with PDCCH monitoring according to corresponding search space set where monitoring implies decoding each PDCCH candidate according to the monitored DCI formats.

[0117] A set of PDCCH candidates for a UE to monitor is defined in terms of PDCCH search space sets. A search space set can be a CSS set or a USS set. A UE may monitor a set of PDCCH candidates in one or more of the following search space sets a TypeO-PDCCH CSS set configured by pdcch-ConfigSIBl in MIB or by searchSpaceSIB 1 in PDCCH-ConfigCommon or by searchSpaceZero in PDCCH- ConfigCommon for a DCI format with CRC scrambled by a SI-RNTI on the primary cell of the MCG a TypeOA-PDCCH CSS set configured by searchSpaceOtherSystemlnformation in PDCCH-ConfigCommon for a DCI format with CRC scrambled by a SI-RNTI on the primary cell of the MCG a Typel-PDCCH CSS set configured by ra-SearchSpace in PDCCH- ConfigCommon for a DCI format with CRC scrambled by a RA-RNTI or a TC-RNTI on the primary cell a Type2-PDCCH CSS set configured by pagingSearchSpace in PDCCH- ConfigCommon for a DCI format with CRC scrambled by a P-RNTI on the primary cell of the MCG a Type3-PDCCH CSS set configured by SearchSpace in PDCCH-Config with searchSpaceType - common for DCI formats with CRC scrambled by INT-RNTI, SFI- RNTI, TPC-PUSCH-RNTI, TPC-PUCCH-RNTI, or TPC-SRS-RNTI and, only for the primary cell, C-RNTI, MCS-C-RNTI, or CS-RNTI(s), and a USS set configured by SearchSpace in PDCCH-Config with searchSpaceType = ue-Specific for DCI formats with CRC scrambled by C-RNTI, MCS-C-RNTI, SP- CSI-RNTI, or CS-RNTI(s).

[0118] For a DL BWP, if a UE is configured (provided) one above-described search space set, the UE may determine PDCCH monitoring occasions for a set of PDCCH candidates of the configured search space set. PDCCH monitoring occasions for monitoring PDCCH candidates of a search space set s is determined according to the search space set s configuration and a CORESET configuration associated with the search space set s. In other words, a UE may monitor a set of PDCCH candidates of the search space set in the determined (configured) PDCCH monitoring occasions in one or more configured control resource sets (CORESETs) according to the corresponding search space set configurations and CORESET configuration. A base station may transmit, to a UE, information to specify one or more CORESET configuration and/or search space configuration. The information may be included in MIB and/or SIBs broadcasted by the base station. The information may be included in RRC configurations or RRC parameters. A base station may broadcast system information such as MIB, SIBs to indicate CORESET configuration or search space configuration to a UE. Or the base station may transmit a RRC message including one or more RRC parameters related to CORESET configuration and/or search space configuration to a UE.

[0119] An illustration of search space set configuration is described below.

[0120] A base station may transmit a RRC message including one or more RRC parameters related to search space configuration. A base station may determine one or more RRC parameter(s) related to search space configuration for a UE. A UE may receive, from a base station, a RRC message including one or more RRC parameters related to search space configuration. RRC parameter(s) related to search space configuration (e.g. SearchSpace, searchSpaceZero) defines how and where to search for PDCCH candidates, ‘search/monitor for PDCCH candidate for a DCI format’ may also refer to ‘monitor/search for a DCI format’ for short.

[0121] For example, a RRC parameter searchSpaceZero is used to configure a common search space 0 of an initial DL BWP. The searchSpaceZero corresponds to 4 bits. The base station may transmit the searchSpaceZero via PBCH(MIB) or ServingCell.

[0122] Additionally, a RRC parameter SearchSpace is used to define how/where to search for PDCCH candidates. The RRC parameters search space may include a plurality of RRC parameters as like, searchSpaceld, controlResourceSetld, monitoringSlotPeriodicityAndOffset, duration, monitoringSymbols WithinSlot, nrofCandidates, searchSpaceType. Some of the above-mentioned RRC parameters may be present or absent in the RRC parameters SearchSpace. Namely, the RRC parameter SearchSpace may include all the above-mentioned RRC parameters. Namely, the RRC parameter SearchSpace may include one or more of the above-mentioned RRC parameters. If some of the parameters are absent in the RRC parameter SearchSpace, the UE 102 may apply a default value for each of those parameters.

[0123] Herein, the RRC parameter searchSpaceld is an identity or an index of a search space. The RRC parameter searchSpaceld is used to identify a search space. Or rather, the RRC parameter serchSpaceld provide a search space set index s, 0<=s<40. Then a search space s hereinafter may refer to a search space identified by index s indicated by RRC parameter searchSpaceld. The RRC parameter controlResourceSetld concerns an identity of a CORESET, used to identify a CORESET. The RRC parameter controlResourceSetld indicates an association between the search space s and the CORESET identified by controlResourceSetld. The RRC parameter controlResourceSetld indicates a CORESET applicable for the search space. CORESET p hereinafter may refer to a CORESET identified by index p indicated by RRC parameter controlResourceSetld. Each search space is associated with one CORESET. The RRC parameter monitoringSlotPeriodicityAndOffset is used to indicate slots for PDCCH monitoring configured as periodicity and offset. Specifically, the RRC parameter monitoringSlotPeriodicityAndOffset indicates a PDCCH monitoring periodicity of k _s slots and a PDCCH monitoring offset of o _s slots. A UE can determine which slot is configured for PDCCH monitoring according to the RRC parameter monitoringSlotPeriodicityAndOffset. The RRC parameter monitoringSymbolsWithinSlot is used to indicate a first symbol(s) for PDCCH monitoring in the slots configured for PDCCH monitoring. That is, the parameter monitoringSymbolsWithinSlot provides a PDCCH monitoring pattern within a slot, indicating first symbol(s) of the CORESET within a slot (configured slot) for PDCCH monitoring. The RRC parameter duration indicates a number of consecutive slots T _s that the search space lasts (or exists) in every occasion (PDCCH occasion, PDCCH monitoring occasion).

[0124] The RRC parameter may include aggregationLevell , aggregationLevel2, aggregationLevel4, aggregationLevel8, aggregationLevell 6. The RRC parameter nrofCandidates may provide a number of PDCCH candidates per CCE aggregation level L by aggregationLevell, aggregationLevel2, aggregationLevel4, aggregationLevel8, and aggregationLevell 6, for CCE aggregation level 1, CCE aggregation level 2, CCE aggregation level 4, for CCE aggregation level 8, and CCE aggregation level 16, respectively. In other words, the value L can be set to either one in the set {1, 2, 4, 8,16}. The number of PDCCH candidates per CCE aggregation level L can be configured as 0, 1, 2, 3, 4, 5, 6, or 8. For example, in a case the number of PDCCH candidates per CCE aggregation level L is configured as 0, the UE may not search for PDCCH candidates for CCE aggregation L. That is, in this case, the UE may not monitor PDCCH candidates for CCE aggregation L of a search space set s. For example, the number of PDCCH candidates per CCE aggregation level L is configured as 4, the UE may monitor 4 PDCCH candidates for CCE aggregation level L of a search space set s. [0125] The RRC parameter searchSpaceType is used to indicate that the search space set s is either a CSS set or a USS set. The RRC parameter searchSpaceType may include either a common or a ue-Specific. The RRC parameter common configure the search space set s as a CSS set and DCI format to monitor. The RRC parameter ue- Specific configures the search space set s as a USS set. The RRC parameter ue-Specific may include dci-Formats. The RRC parameter dci-Formats indicates to monitor PDCCH candidates either for DCI format 0_0 and DCI format 1_0, or for DCI format 0_1 and DCI format 1_1 in search space set s. That is, the RRC parameter searchSpaceType indicates whether the search space set s is a CSS set or a USS set as well as DCI formats to monitor for. The RRC parameter ue-Specific may further include a new RRC parameter (e.g. dci-Formats Ext) in addition to the dci-Formats. The RRC parameter dci-FormatsExt indicates to monitor PDCCH candidates for DCI format 0_2 and DCI format 1_2, or for DCI format 0_1, DCI format 1_1, DCI format 0_2 and DCI format 1_2. If the RRC parameter dci-FormatsExt is included in the RRC parameter ue-Specific, the UE may ignore the RRC parameter dci-Formats. That is to say, the UE may not monitor the PDCCH candidates for DCI formats indicated by the RRC parameter dci-Format and may monitor the PDCCH candidates for DCI formats indicated by the RRC parameter dci-FormatsExt.

[0126] The UE 102 may monitor PDCCH candidates for DCI format 0_0 and/or DCI format 1_0 in either a CSS or a USS. The UE 102 may monitor PDCCH candidates for DCI format 0_1, DCI format 1_1, DCI format 0_2 and/or DCI format 1_2 only in a USS but cannot monitor PDCCH candidates for DCI format 0_1 , DCI format 1_1, DCI format 0_2, and/or DCI format 1_2 in a CSS. The DCI format 0_1 may schedule up to two transport blocks for one PUSCH while the DCI format 0_2 may only schedule one transport blocks for one PUSCH. DCI format 0_2 may not consist of some fields (e.g. ‘CBG transmission information’ field), which may be present in DCI format 0_1. Similarly, the DCI format 1_1 may schedule up to two transport blocks for one PDSCH while the DCI format 1_2 may only schedule one transport blocks for one PDSCH. DCI format 1_2 may not consist of some fields (e.g., ‘CBG transmission information’ field), which may be present in DCI format 1_1. The DCI format 1_2 and DCI format 1_1 may consist of one or more same DCI fields (e.g., ‘antenna port’ field).

[0127] The base station 160 may schedule a UE 102 to receive PDSCH by a downlink control information (DCI). A DCI format provides DCI and includes one or more DCI fields. The one or more DCI fields in a DCI format are mapped to the information bits. As above-mentioned, the UE 102 can be configured by the base station 160 one or more search space sets to monitor PDCCH for detecting corresponding DCI formats. If the UE 102 detects a DCI format (e.g., the DCI format 1_0, the DCI format 1_1, or the DCI format 1_2) in a PDCCH, the UE 102 may be scheduled by the DCI format to receive a PDSCH.

[0128] A USS at CCE aggregation level L is defined by a set of PDCCH candidates for CCE aggregation L. A USS set may be constructed by a plurality of USS corresponding to respective CCE aggregation level L. A USS set may include one or more USS(s) corresponding to respective CCE aggregation level L. A CSS at CCE aggregation level L is defined by a set of PDCCH candidates for CCE aggregation L. A CSS set may be constructed by a plurality of USS corresponding to respective CCE aggregation level L. A CSS set may include one or more CSS(s) corresponding to respective CCE aggregation level L.

[0129] Herein, ‘a UE monitor PDCCH for a search space set s’ also refers to ‘a UE may monitor a set of PDCCH candidates of the search space set s’ . Alternatively, ‘a UE monitor PDCCH for a search space set s’ also refers to ‘a UE may attempt to decode each PDCCH candidate of the search space set s according to the monitored DCI formats’. As above-mentioned, the PDCCH is used for transmitting or carrying Downlink Control Information (DCI). Thus, ‘PDCCH’, ‘DCI’, ‘DCI format’, and/or ‘PDCCH candidate’ are virtually interchangeable. In other words, ‘a UE monitors PDCCH’ implies ‘a UE monitors PDCCH for a DCI format’. That is, ‘a UE monitors PDCCH’ implies ‘a UE monitors PDCCH for detection of a configured DCI format’.

[0130] In the present disclosure, the term “PDCCH search space sets” may also refer to “PDCCH search space”. A UE monitors PDCCH candidates in one or more of search space sets. A search space sets can be a common search space (CSS) set or a UE- specific search space (USS) set. In some implementations, a CSS set may be shared/configured among multiple UEs. The multiple UEs may search PDCCH candidates in the CSS set. In some implementations, a USS set is configured for a specific UE. The UE may search one or more PDCCH candidates in the USS set. In some implementations, a USS set may be at least derived from a value of C-RNTI addressed to a UE.

[0131] An illustration of CORESET configuration is described below. [0132] A base station may configure a UE one or more CORESETs for each DL BWP in a serving cell. For example, a RRC parameter ControlResourceSetZero is used to configure CORESET 0 of an initial DL BWP. The RRC parameter ControlResourceSetZero corresponds to 4 bits. The base station may transmit ControlResourceSetZero, which may be included in MIB or RRC parameter ServingCellConfigCommon, to the UE. MIB may include the system information transmitted on BCH(PBCH). A RRC parameter related to initial DL BWP configuration may also include the RRC parameter ControlResourceSetZero. RRC parameter ServingCellConfigCommon is used to configure cell specific parameters of a UE’s serving cell and contains parameters which a UE would typically acquire from SSB, MIB or SIBs when accessing the cell form IDLE.

[0133] Additionally, a RRC parameter ControlResourceSet is used to configure a time and frequency CORESET other than CORESET 0. The RRC parameter ControlResourceSet may include a plurality of RRC parameters such as, ControlResourceSetld, frequencyDomainResource, duration, cce-REG-MappingType, precoderGranularity, tci-PresentlnDCI, pdcch-DMRS-ScramblingID and so on.

[0134] Here, the RRC parameter ControlResourceSetld is an CORESET index p, used to identify a CORESET within a serving cell, where 0<p< 12. The RRC parameter duration indicates a number of consecutive symbols of the CORESET N _symb ^CORESET , which can be configured as 1, 2 or 3 symbols. A CORESET consists of a set of N _RB ^CORESET resource blocks (RBs) in the frequency domain and N _symb ^CORESET symbols in the time domain. The RRC parameter frequencyDomainResource indicates the set of N _RB ^CORESET RBS for the CORESET. Each bit in the frequencyDomainResource corresponds a group of 6 RBs, with grouping starting from the first RB group in the BWP. The first (left-most I most significant) bit corresponds to the first RB group in the BWP, and so on. The first common RB of the first RB group has common RB index 6×ceiling( N _BWP ^start /6). A bit that is set to 1 indicates that this RB group belongs to the frequency domain resource of this CORESET. Bits corresponding to a group of RBs not fully contained in the bandwidth part within which the CORESET is configured are set to zero. The ceiling(A) function hereinafter is to output a smallest integer not less than A.

[0135] According to the CORESET configuration, a CORESET (a CORESET 0 or a CORESET p) consists of a set of PRBs with a time duration of 1 to 3 OFDM symbols. The resource units Resource Element Groups (REGs) and Control Channel Elements (CCEs) are defined within a CORESET. A CCE consists of 6 REGs where a REG equals one resource block during one OFDM symbol. Control channels are formed by aggregation of CCE. That is, a PDCCH consists of one or more CCEs. Different code rates for the control channels are realized by aggregating different number of CCE. Interleaved and non-interleaved CCE-to-REG mapping are supported in a CORESET. Each resource element group carrying PDCCH carries its own DMRS.

[0136] Figure 4 is a diagram illustrating one 400 example of CORESET configuration in a BWP by a UE 102 and a base station 160.

[0137] Figure 4 illustrates that a UE 102 is configured with three CORESETs for receiving PDCCH transmission in two BWPs. In the Figure 4, 401 represent point A. 402 is an offset in frequency domain between point A 401 and a lowest usable subcarrier on the carrier 403 in number of CRBs, and the offset 402 is given by the offsetToCarrier in the SCS-SpecificCarrier IE. The BWP 405 with index A and the carrier 403 are for a same subcarrier spacing configuration μ. The offset 404 between the lowest CRB of the carrier and the lowest CRB of the BWP in number of RBs is given by the locationAndBandwidth included in the BWP configuration for BWP A. The BWP 407 with index B and the carrier 403 are for a same subcarrier spacing configuration μ. The offset 406 between the lowest CRB of the carrier and the lowest CRB of the BWP in number of RBs is given by the locationAndBandwidth included in the BWP configuration for BWP B.

[0138] For the BWP 405, two CORESETs are configured. As above-mentioned, a RRC parameter frequencyDomainResource in respective CORESET configuration indicates the frequency domain resource for respective CORESET. In the frequency domain, a CORESET is defined in multiples of RB groups and each RB group consists of 6 RBs. For example, in the Figure 4, the RRC parameter frequencyDomainResource provides a bit string with a fixed size (e.g. 45 bits) as like ‘11010000...000000’ for CORESET#1. That is, the first RB group, the second RB group, and the fourth RB group belong to the frequency domain resource of the CORESET# 1. Additionally, the RRC parameter frequencyDomainResource provides a bit string with a fixed size (e.g. 45 bits) as like ‘00101110...000000’ for CORESET#2. That is, the third RB group, the fifth RB group, the sixth RB group and the seventh RB group belong to the frequency domain resource of the CORESET#2. [0139] For the BWP 407, one CORESET is configured. As above-mentioned, a RRC parameter frequencyDomainResource in the CORESET configuration indicates the frequency domain resource for the CORESET #3. In the frequency domain, a CORESET is defined in multiples of RB groups and each RB group consists of 6 RBs. For example, in the Figure 4, the RRC parameter frequencyDomainResource provides a bit string with a fixed size (e.g. 45 bits) as like ‘ 11010000...000000’ for CORESET#3. That is, the first RB group, the second RB group, and the fourth RB group belong to the frequency domain resource of the CORESET#3. Although the bit string configured for CORESET#3 is same as that for CORESET#1, the first RB group of the BWP B is different from that of the BWP A in the carrier. Therefore, the frequency domain resource of the CORESET#3 in the carrier is different from that of the CORESET#1 as well.

[0140] Illustration of SS/PBCH blocks is described hereinafter.

[0141] A SS/PBCH block (or a SSB) is a unit block consisting of primary and secondary synchronization signals (PSS, SSS), each occupying 1 symbol and 127 subcarriers and PBCH spanning across 3 OFDM symbols and 240 subcarriers, but on one symbol leaving an unused part in the middle for SSS as show in Figure 5. Figure 5 is a diagram illustrating one example 500 of SS/PBCH block transmission. The UE 102 receives/detect the SS/PBCH block to acquire time and frequency synchronization with a cell and detect the physical layer Cell ID of the cell. The possible time locations of SS/PBCH blocks within a half-frame are determined by subcarrier spacing and the periodicity of the half-frames where SS/PBCH blocks are transmitted is configured by the base station. During a half frame, different SS/PBCH blocks may be transmitted in different spatial directions (i.e. using different beams, spanning the coverage area of a cell). Within the frequency span of a carrier, multiple SS/PBCH blocks can be transmitted. For a half frame with SS/PBCH blocks, the first symbol indexes for candidate SS/PBCH blocks are determined according to the SCS of SS/PBCH blocks as follows, where index 0 corresponds to the first symbol of the first slot in a half-frame. [0142] Case A-15kHz SCS: the first symbols of the candidate SS/PBCH blocks have indexes of {2,8}+14*n. n ean be either n=0,1 orn=0,1,2,3 depending on the carrier frequencies. [0143] Case B-30kHz SCS: the first symbols of the candidate SS/PBCH blocks have indexes of {4, 8, 16, 20}+28*n. n can be either n=0 or n=0,1 depending on whether the carrier frequencies is larger than 3GHz.

[0144] Case C-30kHz SCS: the first symbols of the candidate SS/PBCH blocks have indexes of {2, 8}+14*n. n can be either n=0,1 or n=0,1 ,2,3 depending on the carrier frequencies.

[0145] Case D - 120 kHz SCS: the first symbols of the candidate SS/PBCH blocks have indexes {4, 8, 16, 20}+28*n where n=0, 1,2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18.

[0146] Case E - 240 kHz SCS: the first symbols of the candidate SS/PBCH blocks have indexes {8, 12, 16, 20, 32, 36, 40, 44}+56*n where n=0,1,2,3,5,6,7,8.

[0147] The maximum number of the SS/PBCH blocks within a half-frame is different for different carrier frequencies. The candidate SS/PBCH blocks in a half frame are assigned an SS/PBCH block index. The candidate SS/PBCH blocks in a half frame are indexed in an ascending order in time from 0 to L _max -1. The UE 102 determines the 2 LSB bits, for L _max =4, or the 3 LSB bits, for L _max >4, of a SS/PBCH block index per half frame form a one-to-one mapping with an index of the DM-RS sequence transmitted in the PBCH. For L _max =64, the UE 102 determines the 3 MSB bits of the SS/PBCH block index per half frame from PBCH payload bits. That is, when the UE 102 detects/receives an SS/PBCH block, the UE 102 calculates an SS/PBCH block index based on PBCH information and/or reference signal information (DMRS sequence) included in the detected SS/PBCH block. Moreover, upon detection of a SS/PBCH block with an index, the UE 102 may determine from the MIB that a CORESET for TypeO-PDCCH CSS set, and the TypeO-PDCCH CSS set.

[0148] Figure 5 is an example of the Case A. In the Figure 5, a half frame 504 has 5 slot. According to the case A, when n=0, 1 , the base station may transmit SS/PBCH blocks in the first two slots within the half frame 504. When n=0,1,2,3, the base station may transmit SS/PBCH blocks in the first four slots within the half frame 504.

[0149] According to the Case A, the index for the first symbol of the first SS/PBCH block with index 0 506 is an index 2 of the first slot 510 in the half-frame 504, the index for the first symbol of the second SS/PBCH block with index 1 508 is an index 8 of the first slot 510 in the half- frame 504, the index for the first symbol of the third SS/PBCH block with index 2 is an index 2 of the second slot 512 in the half-frame 504, and so on. [0150] The UE can be provided per serving cell by a RRC parameter indicating a periodicity of the half frames 502 for reception of the SS/PBCH blocks for the serving cell. If the UE is not provided by the RRC parameter, the periodicity of the half frames 502 for reception of the SS/PBCH blocks is a periodicity of a half frame. In this case, the 502 is equivalent to the 504. The periodicity is same for all SS/PBCH blocks in the serving cell. For example, the SS/PBCH with index 0 506 is transmitted in the slot 510. A next SS/PBCH with index 0 may be transmitted in a slot 514 after the periodicity of half frames 502 starting from the slot 510.

[0151] Additionally, after performing initial cell selection, the UE may assume that half frames with SS/PBCH blocks occur with a periodicity of 2 frames. That is, the UE may receive a SS/PBCH block with an index in a slot and then may further receive a SS/PBCH block with the same index in a slot after the periodicity of 2 frames.

[0152] The base station may transmit a set of SS/PBCH blocks in a serving cell and indicate the indices of the transmitted SS/PBCH blocks within a half-frame to UEs camping on the serving cell via SIB1. In other words, the base station 160 may indicate the time domain positions of the transmitted SS/PBCH blocks within a half frame. As above-mentioned, upon detection of a SS/PBCH block with an index, a UE may determine from the MIB a CORESET for TypeO-PDCCH CSS set and the TypeO- PDCCH CSS set. The UE monitors PDCCH in the Type 0-PDCCH CSS set to receive the SIB1. Then according to the received SIB1, the UE may determine, within a halfframe, a set of SS/PBCH blocks which are transmitted by the base station. In other words, the UE may determine, within a half- frame, the time domain positions of a set of SS/PBCH blocks which are transmitted by the base station.

[0153] Hereinafter, random access procedure is described.

[0154] In the present disclosure, two types of random access procedure are supported, i.e. 4-step random access procedure and 2-step random access procedure. The 4-step random access procedure can be also referred to as Type-1 random access procedure or as 4-step random access type. The 2-step random access procedure can be also referred to as Type-2 random access procedure or as 2-step random access type. Both types of the random access procedure support contention-based random access (CBRA) and contention-free random access (CFRA).

[0155] 4-step Random access procedure may include the transmission of random access preamble (Msgl or Message 1) in a PRACH, the reception of random access response (RAR) message with a PDCCH and/or a PDSCH (Msg2, Message 2), and when applicable, the transmission of a PUSCH scheduled by a RAR UL grant (e.g., Msg 3, Message 3), and the reception of PDSCH for contention resolution.

[0156] 2-step Random access procedure may include the transmission of random access preamble in a PRACH and of a PUSCH (MsgA), and the reception of a RAR message with a PDCCH and/or a PDSCH (MsgB), and when applicable, the transmission of a PUSCH scheduled by a fallback RAR UL grant, and the reception of PDSCH for contention resolution.

[0157] Before initiating a random access procedure, the UE 102 may, based on the received SIB1, obtain a set of SS/PBCH block indexes. A set of SS/PBCH blocks corresponding to the indexes in the set of SS/PBCH block indexes are transmitted by the base station. That is, the base station 160 may notify the UE 102 of the set of SS/PBCH blocks that are transmitted by the base station via a parameter included in the SIB1. The UE 102 may perform reference signal received power (RSRP) measurements for the set of SS/PBCH blocks. On the other hand, the UE 102 may not perform RSRP measurements for those candidate SS/PBCH blocks which are not transmitted by the base station.

[0158] The secondary synchronization signals of a SS/PBCH block is used for the RSRP determination for the corresponding SS/PBCH block. The number of resource elements carrying the secondary synchronization signals of the SS/PBCH block (or the SS/PBCH blocks with the same SS/PBCH block index) within a measurement period may be used by the UE 102 to determine the RSRP of the SS/PBCH block. Additionally, the demodulation reference signals for PBCH of the SS/PBCH block and/or configured CSI reference signals can also be used by the UE 102 to determine the RSRP of the SS/PBCH block.

[0159] Before initiating a random access procedure, the UE 102 may receive, from the base station 160, the information for the random access procedure. The information (i.e. cell specific random access configuration(s)) includes the cell specific random access parameters and/or the dedicated random access parameters. The random access information may be indicated by the broadcasted system information (e.g., MIB, SIB1, and/or other SIBs) and/or RRC message and so on. For example, the information may include the configuration of PRACH transmission parameters such as time resources for PRACH transmission, frequency resources for PRACH transmission, the PRACH preamble format, preamble SCS and so on. The information may also include parameters for determining the root sequences (logical root sequence index, root index) and their cyclic shifts (CSs) in the PRACH preamble sequence set.

[0160] The random access preamble (PRACH preamble, or preamble) sequence is based on the Zadoff-Chu sequence. The logical root for the Zadoff-Chu sequence is provided by the information as above-mentioned. That is, a UE can generate a set of PRACH preamble sequences based on the Zadoff-Chu sequence corresponding to a root sequence indicated by the base station 160. There are two sequence lengths for the preamble. One is 839 and the other one is 139.

[0161] A preamble is transmitted by the UE 102 in a time-frequency PRACH occasion. A PRACH occasion is a time-frequency resource where the base station configures to multiple UEs for preamble transmission. Three are 64 preambles defined in each time-frequency PRACH occasion. In other words, the UE 102 may generate 64 preambles for each PRACH occasion. The preambles (e.g. 64 preambles) in one PRACH occasion may be generated by one root Zadoff-Chu sequence or more than one root Zadoff-Chu sequences. The number of preambles generated from a single root Zadoff-Chu sequence at least depends on the sequence length and/or a distance of the cyclic shifts between two preambles with consecutive preamble indices. The distance of the cyclic shifts is provided by the base station 160.

[0162] Therefore, in some cases, the UE 102 can generate 64 preambles from a single root Zadoff-Chu sequence. In some cases, the UE 102 cannot generate 64 preambles from a single root Zadoff-Chu sequence. In these cases, in order to obtain the 64 preambles in a PRACH occasion, the UE 102 needs to generate the 64 preambles from multiple root Zadoff-Chu sequences with multiple consecutive root indices. The starting root index of the multiple consecutive root indices is indicated by the base station 160. The UE 102 and the base station 160 may enumerate the 64 preambles in increasing order of first increasing cyclic shift (CS) of a logical root Zadoff-Chu sequence, and then in increasing order of the logical root sequence index. The preamble indices for 64 preambles in a PRACH occasion are from 0 to 63.

[0163] The random access information (i.e., random access configuration(s)) may include a RRC parameter indicating how many SS/PBCH blocks is associated with a PRACH occasion. For example, if a value indicated by the RRC parameter is one half (i.e. 1/2), it implies that one SS/PBCH block is associated with two PRACH occasions. For example, if a value indicated by the RRC parameter is two (i.e. 2), it implies that two SS/PBCH blocks are associated with one PRACH occasion.

[0164] In addition, the random access information may include a RRC parameter indicating how many frequency multiplexed PRACH occasions there are in one time instance. The random access information may include a RRC parameter indicating an offset of lowest PRACH occasion in frequency domain with respective to PRB0 of the active UL BWP. The UE 102 may determine starting symbol of a PRACH occasion, a number of PRACH occasions in time domain within a PRACH slot, a duration in symbols of the PRACH occasion according to the random access information.

[0165] As above-mentioned, SIB1 indicates a set of SS/PBCH blocks which are transmitted by the base station. In other words, the SIB1 provides SS/PBCH block indexes with which a set of SS/PBCH blocks are transmitted by the base station. The base station and/or the UE may only map the SS/PBCH indexes provided in the SIB1 to the PRACH occasions in accordance with the following rules: (i) first, in increasing order of preamble indexes within a single PRACH occasion, (ii) second, in increasing order of frequency resource indexes for frequency multiplexed PRACH occasions, (iii) third, in increasing order of time resource indexes for time multiplexed PRACH occasions within a PRACH slot, (iv) in increasing order of indexes for PRACH slots.

[0166] Figure 6 is a diagram illustrating some examples 600-1 and 600-2 of mapping SS/PBCH block indexes to PRACH occasions.

[0167] A RRC parameter (e.g. ssb-perRACH-OccasionAndCB-PreamblesPerSSB) included in a cell specific random access configuration can be used to define a number of SSBs mapped to each PRACH occasion for 4 -step RA type and the number of contention-based Random Access Preambles mapped to each SSB. In the Figure 6A, the random access information indicates that two SS/PBCH blocks are mapped to each PRACH occasion and there are two frequency multiplexed PRACH occasions in one time instance. That is, in the Figure 6 A, the RRC parameter (e.g. ssb-perRACH- OccasionAndCB-PreamblesPerSSB) indicates a value 2 which means two SS/PBCH blocks are mapped to each PRACH occasion. And the random access information indicates that there are two time multiplexed PRACH occasions in one PRACH slot.

[0168] In the Figure 6B, the random access information indicates that 1/2 SS/PBCH blocks are mapped to each PRACH occasion and there are two frequency multiplexed PRACH occasions in one time instance. That is, in the Figure 6 A, the RRC parameter (e.g. ssb-perRACH-OccasionAndCB-PreamblesPerSSB) indicates a value 1/2 which means each SS/PBCH block are mapped to two PRACH occasions. And the random access information indicates that there are two time multiplexed PRACH occasions in one PRACH slot.

[0169] Figure 7 is a diagram illustrating one 700 example of 4-step random access procedure.

[0170] In S 701, the UE 102 may transmit a random access preamble to the base station 160 via a PRACH. The transmitted random access preamble may be referred to as a message 1 (Msg.l, Msgl). The transmission of the random access preamble (i.e. the transmission of the preamble) can be also referred to as PRACH transmission. The Msgl of the 4-step RA type (i.e. 4-step random access procedure) consists of a preamble on PRACH.

[0171] The UE 102 may randomly select a preamble with a random access preamble identity (RAPID) in a PRACH occasion. There are 64 preambles (preamble index) for each PRACH occasion. To be specific, the UE 102 may first measure the reference signal received power (RSRP) of a set of SS/PBCH blocks. If one or more SS/PBCH blocks with measured RSRP value above a threshold in the set of SS/PBCH blocks are available for the UE 102, the UE 102 may select one from the one or more SS/PBCH blocks. If there is no SS/PBCH block with measure RSRP value above the threshold in the set of SS/PBCH blocks, the UE may select one SS/PBCH block from the set of SS/PBCH blocks. The set of SS/PBCH blocks is provided by the SIB1. The threshold is an RSRP threshold for the selection of the SS/PBCH block for the 4-step RA type and is indicated by the base station 160 for example via a RRC parameter e.g. rsrp-ThresholdSSB included in the random access information.

[0172] After selecting the SS/PBCH block, the UE 102 may determine the PRACH occasions corresponding to the selected SS/PBCH block. In a PRACH occasion associated with the selected SS/PBCH block, the UE 102 may randomly select a preamble from a set of preambles associated with the selected SS/PBCH block and transmit it to the base station 160. Herein, the set of preambles associated with the selected SS/PBCH block is specific to the 4-step RA type. In other words, the preamble should be selected from one or more sets of preambles which are specific to the 4-step RA type. [0173] In S 702, if the base station 160 received a preamble in a PRACH occasion, the base station 160 may generate a transport block in response to the reception of the preamble. The transport block (i.e. a MAC PDU) herein is referred to as a random access response (or a random access response message). That is to say, the base station 160 may transmit a PDCCH with a DCI format 1_0 with CRC scrambled by a RA- RNTI and the transport block in a corresponding PDSCH scheduled by the DCI format 1_0. The value of the RA-RNTI is calculated at least based on the time and frequency information of the PRACH occasion where the preamble is received. For example, the RA-RNTI can be calculated as RA-RNTI = 1 + s_id + 14 × t_id + 14 × 80 × f_id + 14 × 80 × 8 × ul_carrier_id. Here, s_ id is the index of the first OFDM symbol of the PRACH occasion (0 ≤ s_id < 14), t_id is the index of the first slot of the PRACH occasion in a system frame (0 ≤ t_id < 80), f id is the index of the PRACH occasion in the frequency domain (0 ≤ f id < 8), and ul carrier id is the UL carrier used for random access preamble transmission ( 0 for NUL carrier, and 1 for SUL carrier).

[0174] In S 702, in response to the transmission of the preamble, the UE 102 may attempt to detect a DCI format 1_0 with CRC scrambled by the RA-RNTI as above- mentioned during a window in the Type 1 -PDCCH CSS set. The length of the window in number of slots, based on the SCS for Type 1 -PDCCH CSS set, is provided by the base station 160 for example via the SIB1. And the window start at the first symbol of the earliest COREET where the UE 102 is configured to receive PDCCH for Type 1- PDCCH CSS set, that is at least one symbol after the last symbol of the PRACH occasion where the preamble is transmitted. The symbols duration corresponds to the SCS for Type 1 -PDCCH CSS set.

[0175] If the UE 102 detects the DCI format 1_0 with CRC scrambled by the RA- RNTI, the UE 102 may receive a transport block in a corresponding PDSCH scheduled by the DCI format 1_0 within the window. The UE may parse the transport block (i.e. the MAC PDU) for a random access preamble identity (RAPID) associated with the transmitted preamble.

[0176] A MAC PDU (i.e. random access response, RAR) consists of one or more MAC subPDUs and optionally padding. Each MAC subPDU consists one of the followings: (i) a MAC subheader with Backoff Indicator only, (ii) a MAC subheader with RAPID only, and (iii) a MAC subheader with RAPID and MAC RAR. A MAC RAR is of fixed size and consists of reserved bit, Timing Advance command, UL grant, and temporary C-RNTI. A UL grant include in the MAC RAR can be referred to as a RAR UL grant.

[0177] A MAC subheader with Backoff Indicator consists of five header fields E/T/R/R/BI. A MAC subPDU with Backoff Indicator only is placed at the beginning of the MAC PDU, if included. 'MAC subPDU(s) with RAPID only' and 'MAC subPDU(s) with RAPID and MAC RAR' can be placed anywhere between MAC subPDU with Backoff Indicator only (if any) and padding (if any). Padding is placed at the end of the MAC PDU if present. Presence and length of padding is implicit based on TB size and size of MAC subPDUs.

[0178] If the RAPID in RAR message(s) (i.e. MAC subPDU(s)) of the transport block is identified, the UE may obtain an uplink grant which is also referred as a RAR UL grant. That is, if there is a MAC subPDU with a RAPID corresponding to the RAPID of the preamble which is transmitted by the UE 102, the UE 102 may obtain a RAR UL grant provided by the MAC RAR included in the MAC subPDU with the RAPID corresponding to the transmitted preamble. The size of the RAR UL grant is 27bits. The RAR UL grant is used to indicate the resources to be used for the PUSCH transmission. That is, the RAR UL grant is used to schedule a PUSCH transmission for the UE 102. In addition to the RAR UL grant, the MAC subPDU may also provide, to the UE 102, a timing advance command field with 12 bits, a Temporary C-RNTI field with 16bits and a reserved bit with Ibit.

[0179] Figure 8 is a diagram illustrating one 800 example of fields included in an RAR UL grant. The RAR UL grant may at least include the fields as given in the Figure 8. The fields of the RAR UL grant starts with the MSB of the RAR UL grant and ends with the LSB of the RAR UL grant.

[0180] In a case that the value of a frequency hopping flag is 0, the UE 102 may transmit the PUSCH scheduled by the RAR UL grant without frequency hopping. In a case that the value of a frequency hopping flag is 1, the UE 102 may transmit the PUSCH scheduled by the RAR UL grant with frequency hopping. The ‘PUSCH time resource allocation’ field is used to indicate resource allocation in the time domain for the PUSCH scheduled by the RAR UL grant. The ‘MCS’ field is used to determine an MCS index for the PUSCH scheduled by the RAR UL grant. The ‘TPC command for PUSCH’ field is used for setting the power of the PUSCH scheduled by the RAR UL grant. The ‘CSI request’ field is reserved. The ‘PUSCH frequency resource allocation’ field is used to indicate resource allocation in the frequency domain for the PUSCH scheduled by the RAR UL grant.

[0181] On the other hand, if the UE 102 does not detect the DCI format 1_0 with CRC scrambled by the corresponding RA-RNTI within the window, or if the UE 102 does not correctly receive the transport block in the corresponding PDSCH within the window, or if the UE 102 do not identify the RAPID associated with the transmitted preamble from the UE 102, the UE may transmit a PRACH one more time. That is, the UE 102 may perform S 701.

[0182] In S 703, the UE 102 transmits, to the base station, a transport block in the PUSCH scheduled by the MAC RAR in the active UL BWP. To be specific, the PUSCH is scheduled by a RAR UL grant included in the MAC RAR. The transport block may contain a UE identity, for example, a CCCH SDU, a C-RNTI MAC CE. The PUSCH containing a CCCH SDU or a C-RNTI MAC CE can be also referred to as Msg 3 (Message 3).

[0183] The base station 160 may not successfully decode the transport block which is transmitted by the UE 102 in the PUSCH scheduled by the RAR UL grant. Then, the base station 160 may request the UE 102 to retransmit the transport block. In this case, the base station 160 may generate a DCI format 0_0 with CRC scrambled by the TC- RNTI for a corresponding PUSCH retransmission of the transport block. And the base station 160 may transmit the DCI format 0_0 with CRC scrambled by the TC-RNTI to the UE 102 in S 703a. As above-mentioned, the TC-RNTI is provided in the corresponding MAC RAR (RAR message).

[0184] After transmitting the PUSCH scheduled by the RAR UL grant, the UE 102 may receive a PDCCH with a DCI format 0_0 with CRC scrambled by the TC-RNTI. In this case, the UE 102 may perform a corresponding PUSCH retransmission scheduled by the DCI format 0_0 in S 703b. The PUSCH retransmission of the transport block is scheduled by the DCI format 0_0 with CRC scrambled by the TC-RNTI.

[0185] In S 704, if the base station 160 successfully decoded the transport block, the base station 160 may generate and transmit a DCI format 1_0 with CRC scrambled by the TC-RNTI scheduling a PDSCH that includes a UE contention resolution identity (i.e. a UE contention resolution identity MAC CE). The UE contention resolution identity contains the CCCH SDU transmitted in the S 703. The UE resolution identity MAC CE contains part or all of the CCCH SDU transmitted by the UE 102 (UL CCCH SDU). If the UL CCCH SDU is longer than 48bits, the UE resolution identity MAC CE contains the first 48 bits of the UL CCCH SDU.

[0186] The UE contention resolution identity contributes to resolving contention between multiples UEs who transmitted a same preamble in a same PRACH occasion. A UE may compare the UE contention resolution identity received in the S 704 with the CCCH SDU transmitted in the S 703. If the UE contention resolution identity matches the transmitted CCCH SDU, the UE 102 considers the contention resolution successful and considers the random access procedure successfully completed. On the other hand, if the UE contention resolution identity does not match the transmitted CCCH SDU, the UE 102 considers the contention resolution not successful.

[0187] In response to the PDSCH reception with the UE contention resolution identity, the UE 102 may transmit HARQ-ACK information in a PUCCH using frequency hopping to the base station 160. The UE 102 may generate one HARQ-ACK information bit in response to the PDSCH reception with the UE contention resolution identity. The UE 102 may transmit a PUCCH with the HARQ-ACK information in a cell specific PUCCH resource in the initial UL BWP.

[0188] Figure 9 is a diagram illustrating some examples 900-1 and 900-2 of 2-step random access procedure. Figure 9Ais a diagram illustrating one example 900-1 of 2- step random access procedure. Figure 9B is a diagram illustrating one example 900-2 of 2-step random access procedure with fallback indication.

[0189] In S901 of the Figure 9A, the UE 102 may transmit a random access preamble to the base station 160 via a PRACH. The UE 102 may select a preamble randomly with equal probability from a set of preambles associated with the selected SS/PBCH blocks. Herein, the set of preambles is specific to the 2-step RA type. The selection of the SS/PBCH block for the 2-step RA type is same as that for the 4-step RA type. The RSRP threshold for the selection of the SS/PBCH for 2-step RA type can be separately configured by the base station 160. For example, a RRC parameter msgA- RSRP-ThresholdSSB included in the random access information can be used to indicate an RSRP threshold for the selection of the SS/PBCH block for 2-step RA type.

[0190] After the transmission of the preamble in a PRACH occasion, the UE 102 may transmit S902 a PUSCH. The UE 102 may encode a transport block provided for the PUSCH transmission using redundancy version number 0. The PUSCH transmission is performed in a PUSCH occasion. The PUSCH occasion is mapped to the transmitted preamble of the PRACH occasion. The UE 102 may select a PUSCH occasion from the PUSCH occasions

[0191] One or multiple consecutive preambles from valid PRACH occasions in a PRACH slot are mapped to a PUSCH occasion associated with a DMRS resource. A PUSCH occasion for PUSCH transmission is defined by a frequency resource and a time resource and is associated with a DMRS resource. A DMRS resource corresponds to a DMRS port and/or a DMRS sequence index. Up to 2 DMRS sequences can be generated via two scrambling IDs which are used to DMRS scrambling initialization. According to the mapping, the UE 102 may select a PUSCH occasion corresponding to the selected preamble and PRACH occasion.

[0192] In S903, the base station 160 may receive the transmitted preamble and PUSCH from the UE 102. That is, the base station 160 may detect the preamble from the UE and also successfully decodes the PUSCH from the UE 102. In response to the reception of the preamble and the PUSCH, the base station 160 may generate a transport block and a DCI format 1_0 scheduling the transport block. The base station 160 may transmit a PDCCH with a DCI format 1_0 with CRC scrambled by a MSGB-RNTI and the transport block in a corresponding PDSCH scheduled by the DCI format 1_0. The value of the MSGB-RNTI is calculated at least based on the time and frequency information of the PRACH occasion where the preamble is received. For example, the MSGB-RNTI can be calculated by the base station 160 and the UE 102 as MSGB-RNTI = 1 + s_id + 14 × t_id + 14 × 80 × f id + 14 × 80 × 8 × ul_carrier_id+14 × 80 × 8 × 2. Given the addition of 14 × 80 × 8 × 2 in calculation of MSGB-RNTI, the value of MSGB-RNTI is different from that of RA-RNTI.

[0193] In S903, in response to the transmission of the preamble and the PUSCH (i.e. the transmission of MsgA), the UE 102 may attempt to detect a DCI format 1_0 with CRC scrambled by the MSGB-RNTI as above-mentioned during a window configured by higher layers in the Typel -PDCCH CSS set. In S903, the UE 102 may receive a transport block in a corresponding PDSCH scheduled by the detected DCI format 1_0. The transport block (i.e. a MAC PDU) herein can be referred to as MSGB. In other words, the RAR message received within the 4-step random access procedure can be referred to as Msg2. On the other hand, the RAR message received within the 2- step random access procedure can be referred to as MSGB. [0194] A MAC PDU (i.e. MSGB) consists of one or more MAC subPDUs and optionally padding. Each MAC subPDU consists one of the followings: (i) a MAC subheader with Backoff Indicator only, (ii) a MAC subheader and fallbackRAR, (iii) a MAC subheader and successRAR, (iv) a MAC subheader and MAC SDU for CCCH or DCCH, and (v) a MAC subheader and padding. Fields in a MAC subheader indicates a corresponding MAC subPDU with the MAC subheader is which above-mentioned MAC subPDU.

[0195] The successRAR is of fixed size and consists of UE contention resolution identity, reserved bit, TPC command, HARQ Feedback Timing indicator, PUCCH resource indicator, Timing Advance command, C-RNTI, and so on. The fallbackRAR, which has same format as the MAC RAR, consists of reserved bit, Timing Advance command, UL grant, and temporary C-RNTI. A UL grant included in the fallbackRAR (or MSGB) can be referred to as a fallbackRAR UL grant. SuccessRAR does not have a UL grant.

[0196] In S903, the UE 102 may receive the MSGB which contains a suscessRAR MAC subPDU. And the UE contention resolution identity in the MAC subPDU matches the CCCH SDU transmitted in the S903. In this case, the UE 102 considers the random access response reception successful and considers the random access procedure successfully completed. Herein, to the UE 102, the RAR message is for successRAR. The UE 102 may perform a transmission of a PUCCH with HARQ-ACK information having ACK value. The PUCCH resource for the transmission of the PUCCH is determined based on the successRAR.

[0197] Figure 9B illustrates one example of 2-step random access procedure with fallback indication. The above description for S901 and S902 of the Figure 9A can equally apply to that for S911 and S912 of the Figure 9B.

[0198] In S913, the base station 160 may successfully detect the preamble transmitted by the UE 102 in S911 but fails to decode the PUSCH transmitted by the UE 102 in S912. In this case, the base station 160 may generate a transport block including a MAC subPDU with fallbackRAR and generate a DCI format 1_0 scheduling the transport block. The base station 160 may transmit a PDCCH with a DCI format 1_0 with CRC scrambled by a MSGB-RNTI and the transport block in a corresponding PDSCH scheduled by the DCI format 1_0. The calculation of MSGB- RNTI is same as above-mentioned. [0199] In S913, the UE 102 may detect the DCI format 1_0 and receive a transport block in a corresponding PDSCH scheduled by the detected DCI format 1_0. If there in a MAC subPDU with a RAPID that matches the transmitted preamble by the UE 102 in S911, the UE 102 may consider the random access response reception successful. The UE 102 obtains a fallbackRAR in the MAC subPDU. Herein, to the UE 102, the RAR message is for fallbackRAR.

[0200] In S914, the UE 102 transmits, to the base station 160, a transport block in a PUSCH scheduled by the fallbackRAR in the active UL BWP. To be specific, the PUSCH is scheduled by a fallbackRAR UL grant included in the fallbackRAR. The transport block may contain a UE identity, for example, a CCCH SDU, a C-RNTI MAC CE.

[0201] In S915 , if the base station 160 successfully decoded the transport block, the base station 160 may generate and transmit a DCI format 1_0 with CRC scrambled by the TC-RNTI scheduling a PDSCH that includes a UE contention resolution identity (i.e. a UE contention resolution identity MAC CE). The UE contention resolution identity contains the CCCH SDU transmitted in the S914. The UE resolution identity MAC CE contains part or all of the CCCH SDU transmitted by the UE 102 (UL CCCH SDU). If the UL CCCH SDU is longer than 48bits, the UE resolution identity MAC CE contains the first 48 bits of the UL CCCH SDU.

[0202] If the UE contention resolution identity matches the transmitted CCCH SDU, the UE 102 considers the contention resolution successful and considers the random access procedure successfully completed. On the other hand, if the UE contention resolution identity does not match the transmitted CCCH SDU, the UE 102 considers the contention resolution not successful.

[0203] In NR Release 15/16, the maximum bandwidth that NR Release 15/16 UEs (i.e. legacy UEs) can support are up to 100MHz for FR1 and 200MHz for FR2. Compared with the Release 15/16 UEs, cost reduction for a new UE type (e.g., wearable devices, industrial sensors, video surveillance) is desirable. To reduce the cost and the complexity, the UE with new type would be equipped with less reception antennas and/or the reduced bandwidth (i.e. RF bandwidth and/or baseband bandwidth) relative to the NR Release 15/16 UEs. The reduced reception antennas would result in a reduced power for the received channels/signals. The reduced bandwidth would also result in a reduced frequency diversity. The maximum bandwidth that UEs with reduced bandwidth can support may be, for example, 20MHz for FR1 and 100MHz for FR2. This kind of UEs can be termed ‘RedCap (reduced capability) UEs’. The NR Release 15/16 UEs can be termed ‘non-RedCap UEs’. Additionally, UEs other than RedCap UEs can be termed ‘non-RedCap UEs’. Unless otherwise specified, a UE 102 hereinafter in the present disclosure may refer to the RedCap UEs with reduced bandwidth including reduced RF bandwidth and/or reduced baseband bandwidth. That is, the maximum bandwidth the UE 102 can support may be 20MHz for FR1 and may be 100MHz for FR2.

[0204] In a serving cell, the base station may configure BWPs (DL BWPs and /or UL BWPs) with different bandwidths and different frequency locations for different UEs. For a UE, a configurable bandwidth of a BWP (a DL BWP and/or a UL BWP) is subject to the UE’s bandwidth capability, i.e. the maximum bandwidth the UE can support. The base station may not configure a UE with a BWP whose bandwidth is wider than the maximum bandwidth the UE can support. The UE may not operate with a BWP whose bandwidth is wider than the maximum bandwidth the UE can support. In a serving cell, due to different bandwidth capabilities of different UEs, for example, the base station may configure a non-RedCap UE with a BWP whose bandwidth can be up to 100MHz, and may configure a RedCap UE with a BWP whose bandwidth can be up to 20MHz.

[0205] As above-mentioned, the RedCap UEs and the non-RedCap UEs have different reception performance and different bandwidth capabilities. Therefore, in a cell on which both RedCap UEs and non-RedCap UEs are allowed to camp, the base station may need to distinguish which UE is a RedCap UE and which UE is non- RedCap UE during initial access such that the base station 160 can provide proper configuration(s) to different UEs. That is, when a UE in idle mode (i.e. RRC IDLE) performs initial access (initial random access) to the cell, it is beneficial for the base station 160 to know whether the UE is a RedCap UE. Without such a kind of early indication during initial access, the base station 160 may have to treat both RedCap UE and non-RedCap UE the same and take conservative scheduling to all UEs.

[0206] On the other hand, in order to support the early indication of RedCap UEs, the base station 160 needs to additionally provide random access resource for the RedCap UE to perform random access, which also would increase resource overhead. Therefore, whether to enable the early indication or disable the early indication may depend on whether the bases station 160 needs to know a UE accessing a cell is a RedCap UE during initial access.

[0207] In various implementations of the present disclosure, ‘enabling early indication of RedCap UEs for a RA type in a UL BWP’ may mean ‘a UL BWP is configured with random access resources specific to RedCap UEs for a RA type’, while ‘disabling early indication of RedCap UEs for a RA type in a UL BWP’ may mean ‘a UL BWP is not configured with random access resources specific to RedCap UEs for a RA type’. Random access resources specific to RedCap UEs can be configured by a cell specific random access configuration (e.g. a second cell specific random access configuration and/or a fourth cell specific random access configuration). On the other hand, random access resources can be configured by a cell specific random access configuration (e.g. a first cell specific random access configuration and/or a third cell specific random access configuration). The specific illustrations for the first, the second, the third and the fourth cell specific random access configuration are described below. Hereinafter, unless otherwise specified, random access resources mean random access resources other than random access resources specific to RedCap UEs. Non-RedCap UEs may use the random access resources to perform PRACH transmission and may not use the random access resources specific to RedCap UEs to preform PRACH transmission. RedCap UEs may use random access resources specific to RedCap UEs to preform PRACH transmission. Additionally, RedCap UEs may also use random access resources to perform PRACH transmission.

[0208] Figure 10 is a flow diagram illustrating one implementation of a method 1000 for applying RRC parameter(s) for random access initialization by a UE 102.

[0209] In the implementation of the present disclosure, the base station may enable early indication of RedCap UEs, while the UE 102 may need to determine how to apply parameters to determine random access resource to perform initial random access based on the configuration for the early indication of RedCap UE.

[0210] The UE 102 may receive 1002, from a base station 160, system information including a first cell specific random access configuration. In various implementations of the present disclosure, the system information may be the SIB1. Or the system information may be other system information broadcasted by the base station 160. (e.g., MIB or other SIBs). The first cell specific random access configuration (e.g., rach- ConfigCommon) may be a configuration of cell specific random access parameters which the UE 102 used for random access in an UL BWP. That is, the first cell specific random access configuration is used to specify the cell specific random access parameters. Additionally, the first cell specific random access configuration is used for 4-step random access type.

[0211] The UE 102 may receive 1004, from a base station 160, system information including a second cell specific random access configuration. The second cell specific random access configuration (e.g., rach-ConfigCommon-redCap) may be a configuration of cell specific random access parameters which the UE 102 used for random access in an UL BWP. That is, the second cell specific random access configuration is used to specify the cell specific random access parameters. Additionally, the second cell specific random access configuration is used for 4-step random access type as well.

[0212] The second cell specific random access configuration is specific to RedCap UEs. In other words, the second cell specific random access configuration is used for early indication of RedCap UEs during 4-step initial access. Hereinafter, the second cell specific random access configuration can be called the second configuration for short. Likewise, the first cell specific random access configuration can be called the first configuration for short. In other words, cell specific random access configuration can be called configuration for short unless otherwise specified.

[0213] The second configuration may provide the UE 102 sets of PRACH occasions and/or sets of preambles (i.e. random access resources), which are different from those provided by the first configuration, for PRACH transmission. To be specific, the sets of PRACH occasions provided by the second configuration do not overlap with the sets of PRACH occasions provided by the first configuration. Or, even if the sets of PRACH occasions provided by the second configuration are as same as the sets of PRACH occasions provided by the first configuration, the preambles provided by the second configuration in a PRACH occasion are different from the preambles provided by the first configuration in the same PRACH occasion. Herein, ‘a preamble is different from another preamble’ may mean ‘the index of a preamble is different from the index of another preamble if these two preambles are within a same PRACH occasion’. Additionally or alternatively, ‘a preamble is different from another preamble’ may mean ‘these two preambles are within different PRACH occasions’. And their preamble indexes can be same or different. [0214] Through separating random access resources provided by the second configuration from those provided by the first configuration (i.e. different PRACH occasions and/or different preambles), the bases station 160 can distinguish whether the UE who attempts to perform random access is a RedCap UE or not. Non-RedCap UEs may use the random access resources provided by the first configuration to perform PRACH transmission and may not use the random access resources provided by the second configuration to preform PRACH transmission. RedCap UEs may use random access resources provided by the second configuration to preform PRACH transmission. Additionally, RedCap UEs may also use random access resources provided by the first configuration to perform PRACH transmission.

[0215] The UE 102 may determine 1006 whether the second configuration includes a RRC parameter to be used for PRACH transmission. That is, the UE 102 may determine 1006 how to perform initialization of RRC parameters for random access procedure based on the configured cell specific random access configuration(s). The base station 160 may determine to receive a PRACH transmission from a UE 102 based on the cell specific random access configuration(s) configured to the UE 102. ‘The UE 102 perform initialization of RRC parameters’ may mean ‘the UE 102 applies RRC parameters from one or more configured cell specific random access configurations’. In other words, the UE 102 may determine 1006 to apply which RRC parameter(s) in which cell specific random access configuration to perform initialization of the random access variables (i.e. the RRC parameters) to be used for the random access procedure. The following steps including 1006 may be implemented by the UE 102 after the UE 102 determines to select 4-step RAtype for random access procedure.

[0216] In an example of the implementation, the UE 102 may determine 1006 whether the second configuration includes a second RRC parameter. In a case that the second configuration includes the second parameter, the UE 102 may 1008 apply the second parameter for PRACH transmission. In this case, the base station 160 may determine to receive a PRACH transmission based on the second parameter. In a case that the second configuration does not include the second parameter, the UE 102 may 1010 apply a first parameter for PRACH transmission. The first parameter is included in the first configuration. In this case, the base station 160 may determine to receive a PRACH transmission based on the first parameter. [0217] Both the first parameter and the second parameter are used to define a number of SSBs mapped to each PRACH occasion for 4-step RA type and the number of contention-based Random Access Preambles mapped to each SSB. The first parameter (e.g. ssh-perRACH-OccasionAndCB-PreamblesPerSSB) and the second parameter (e.g. ssb-perRACH-OccasionAndCB-PreamblesPerSSB-redCap) may indicate a number of SSBs mapped to each PRACH occasion for 4-step RA type and the number of contention-based Random Access Preambles mapped to each SSB, respectively. The number of SSBs mapped to each PRACH occasion indicated by the first parameter can be different from or same as that indicated by the second parameter. Likewise, the number of contention-based random access preambles mapped to each SSB indicated by the first parameter can be different from or same as that indicated by the second parameter. The first parameter (e.g. ssb-perRACH-OccasionAndCB- PreamblesPerSSB) can be applied to RedCap or early indication of RedCap UEs if the second parameter (e.g. ssb-perRACH-OccasionAndCB-PreamblesPerSSB-redCap) is not configured. Based on the applied parameter, the UE 102 and the base station 160 may determine the mapping of PRACH occasions and SS/PBCH blocks transmitted by the base station and then may determine how to select a PRACH occasion and a preamble associated to a selected SS/PBCH block for PRACH transmission.

[0218] In an example of the implementation, the UE 102 may determine 1006 whether the second configuration includes a fourth RRC parameter. In a case that the second configuration includes the fourth parameter, the UE 102 may 1008 further apply the fourth parameter for PRACH transmission. In this case, the base station 160 may determine to receive a PRACH transmission based on the fourth parameter. In a case that the second configuration does not include the fourth parameter, the UE 102 may 1010 apply a third parameter for PRACH transmission. The third parameter is included in the first configuration. In this case, the base station 160 may determine to receive a PRACH transmission based on the third parameter.

[0219] For example, both the third parameter and the fourth parameter are used to indicate a total number of preambles used for 4-step random access in a PRACH occasion. The total number of preambles indicated by the third parameter (e.g. TotalNumberOfRA-Preambles) can be different from or same as that indicated by the fourth parameter (e.g. TotalNumberOfRA-Preambles-redCap). The third parameter (e.g. TotalNumberOfRA-Preambles) can be applied to RedCap or early indication of RedCap UEs if the fourth parameter (e.g. TotalNumberOfRA-Preambles-redCap is not configured. Based on the applied parameter, the UE 102 and the base station 160 may determine a preamble associated to a selected SS/PBCH block for PRACH transmission. [0220] Additionally or alternatively, both the third parameter and the fourth parameter are used to indicate an RSRP threshold for the selection of the SSB for 4- step RA type. The RSRP threshold indicated by the third parameter (e.g. rsrp- ThresholdSSB) can be different from or same as that indicated by the fourth parameter (e.g. rsrp-ThresholdSSB-redCap). The third parameter (e.g. rsrp-ThresholdSSB) can be applied to RedCap or early indication of RedCap UEs if the fourth parameter (e.g. rsrp- ThresholdSSB-redCap is not configured. Based on the applied parameter, the UE 102 may determine which SS/PBCH block should be selected for PRACH transmission. [0221] Additionally or alternatively, both the third parameter and the fourth parameter are used to indicate a power ramping factor. The power ramping factor indicated by the third parameter (e.g. power RampingStep) can be different from or same as that indicated by the fourth parameter (e.g. power RampingStep). The third parameter (e.g. power RampingStep) can be applied to RedCap or early indication of RedCap UEs if the fourth parameter (e.g. powerRampingStep-redCap is not configured. Based on the applied parameter, the UE 102 and/or the base station 160 may determine the transmission power and/or the reception power for the retransmitted preamble.

[0222] To reduce the latency of initial access and control channel signaling overhead, the base station 160 may configure the UE 102 with 2-step RA type for a UL BWP via system information. In a case that a UL BWP selected by the UE 102 for random access is configured with both 4-step RA type random access resources and 2- step RA type random access resources, the UE 102 may select one RA type for random access based on whether a RSRP of the downlink pathloss reference is above a RSRP threshold. The RSRP threshold can be indicated by a RRC parameter included in a third cell specific random access configuration which is used for 2-step random access type. In a case that the RSRP of the downlink pathloss reference is above the RSRP threshold, the UE 102 may perform the 2-step random access procedure. In a case that the RSRP of the downlink pathloss reference is not above the RSRP threshold, the UE 102 may perform the 4-step random access procedure.

[0223] Furthermore, in addition to being configured with 4-step and 2-step random access resources, the UE 102 may also be configured with random access resources specific to RedCap UEs for 4-step RA type and/or 2-step RA type. To have a more flexible and efficient communication, solutions on how to select 4-step and 2-step and/or random access resource for random access are illustrated.

[0224] Figure 11 is a flow diagram illustrating one implementation of a method 1100 for selection of 4-step RA type and 2-step RA type by a UE 102.

[0225] In the implementation of the present disclosure, the base station may enable or disable early indication of RedCap UEs for 4-step RA type and/or 2-step RA type.

[0226] The base station 160 may configure 1102 the UE with 4-step random access resources via system information. The UE 102 may receive 1102, from a base station 160, system information including a first cell specific random access configuration (e.g., rach-ConfigCommon). The first cell specific random access configuration may be a configuration of cell specific random access parameters which the UE 102 used for random access in an UL BWR That is, the first cell specific random access configuration is used to specify the cell specific random access parameters. Additionally, the first cell specific random access configuration is used for 4-step random access type. In the implementation of the present disclosure, the UL BWP can be referred to as the initial UL BWR

[0227] The base station 160 may configure 1102 the UE with 2-step random access resources via system information. The UE 102 may receive 1102, from a base station 160, system information including a third cell specific random access configuration (e.g., msgA-ConfigCommon). The third cell specific random access configuration may be a configuration of cell specific PRACH (random access) and PUSCH resource parameters which the UE 102 used for transmission of MsgA in 2-step random access type procedure. The third cell specific random access configuration can be called third configuration for shot. That is, the third configuration is used to configure the PRACH (random access) and PUSCH resource for transmission of MsgA in 2-step random access type procedure in an UL BWP.

[0228] Therefore, in 1102, the base station 160 may configure the UE 102 with both 2-step RA type random access resources and 4-step RA type random access resources for the UL BWP. In 1102, the UE 102 may receive, from the base station 160, the first configuration and the third configuration for 4-step RA type random access resources and 2-step RA type random access resources for the UL BWP, respectively. [0229] In the implementation 1100, the base station 160 may enable or disable early indication of RedCap UEs for a RA type in a UL BWR The base station 160 may configure 1104 the UE with 4-step random access resources specific to RedCap UEs via system information. The UE 102 may receive 1104, from a base station 160, system information including the second cell specific random access configuration (e.g., rach- ConfigCommon -redCap). The description of the second cell specific random access configuration in implementation 1000 can equally apply to that of the second cell specific random access configuration herein in implementation 1100.

[0230] In the implementation 1100, the base station 160 may configure 1104 the UE with 2-step random access resources specific to RedCap UEs via system information. The UE 102 may receive 1104, from a base station 160, system information including a fourth cell specific random access configuration (e.g., msgA- ConfigCommon-redCap). The fourth cell specific random access configuration is specific to RedCap UEs. The fourth cell specific random access configuration is used for early indication of RedCap UEs during 2-step initial access. Hereinafter, the fourth cell specific random access configuration can be called the fourth configuration for short. The fourth configuration is used to configure the PRACH (random access) and PUSCH resource for transmission of MsgA in 2-step random access type procedure in the UL BWP. The random access resources and PUSCH resources configured by the fourth configuration are specific to RedCap UEs. The random access resources (i.e. set of PRACH occasions and/or sets of preambles) and PUSCH resources configured by the fourth configuration are different from those provided by the third configuration. Herein, ‘different PUSCH resources’ means ‘two PUSCH resources do not overlap with either other in both the frequency and time domain’.

[0231] That is, in the implementation of the present disclosure, random access resources provided by the four configurations are separated from each other. According to the separated random access resources, the base station 160 can distinguish whether a UE who attempts to perform random access is a RedCap UE or not and whether the UE attempts to perform a 4-step RA procedure or a 2-step RA procedure. The UE 102 may determine to select one of the 2-step random access procedure and the 4-step random access procedure and select which random access resources for random access procedure. [0232] In the implementation, a UE 102 may receive, from the base station 160, one, more, or all of the first configuration, the second configuration, the third configuration and the fourth configuration in system information for the UL BWP. That is, the UL BWP is configured with one, more, or all of 4-step random access resources, 4-step random access resources specific to RedCap UEs, 2-step random access resources, and 2-step random access resources specific to RedCap UEs.

[0233] In an example of the implementation, the UE 102 may determine 1106 to select one of the 4-step RA type and the 2-step RA type based on whether random access resources specific to RedCap UEs are configured for a UL BWP wherein the UL BWP is selected by the UE 102 to perform random access procedure. The UE 102 may determine 1106 to select one of random access resources and random access resources specific to RedCap UEs based on whether the random access resources specific to RedCap UEs are configured for the RA type for the UL BWP. The UL BWP hereinafter refers to a UL BWP which the UE 102 selects to perform random access procedure. The UL BWP may be an initial UL BWP indicated by the system information.

[0234] In a case that the UL BWP is configured with both 4-step random access resources specific to RedCap UEs and 2-step random access resources specific to RedCap UEs, the UE 102 may select one of 4-step RA type and 2-step RA type to perform/initiate random access procedure based on the RSRP of the downlink pathloss reference. The UE 102 may apply a cell specific random access configuration corresponding to the selected RA type to perform the random access procedure. Herein, the UL BWP may or may not be configured with 4-step random access resources and/or 2-step random access resources.

[0235] Additionally or alternatively, in a case that the UL BWP is configured with 4-step random access resources specific to RedCap UEs and is not configured with 2- step random access resources specific to RedCap UEs, the UE 102 may select 4-step RA type to perform/initiate random access procedure. That is, in this case, the UE 102 may select 4-step RA type not based on the RSRP of the downlink pathloss reference. The UE 102 may apply the cell specific random access configuration corresponding to the selected 4-step RA type to perform the random access procedure. Herein, the UL BWP may or may not be configured with 4-step random access resources and/or 2-step random access resources. [0236] Additionally or alternatively, in a case that the UL BWP is not configured with 4-step random access resources specific to RedCap UEs and is not configured with 2-step random access resources specific to RedCap UEs, the UE 102 may select one of 4-step RA type and 2-step RA type to perform/initiate random access procedure based on the RSRP of the downlink pathloss reference. The UE 102 may apply a cell specific random access configuration corresponding to the selected RA type to perform the random access procedure. Herein, the UL BWP is configured with 4-step random access resources and/or 2-step random access resources.

[0237] Additionally or alternatively, in a case that the UL BWP is configured with 2-step random access resources specific to RedCap UEs and is not configured with 4- step random access resources specific to RedCap UEs, the UE 102 may select 2-step RA type to perform/initiate random access procedure. That is, in this case, the UE 102 may select 2-step RA type not based on the RSRP of the downlink pathloss reference. On the other hand, in this case, the UE 102 may select one of 4-step RA type and 2-step RA type to perform/initiate random access procedure based on the RSRP of the downlink pathloss reference. The UE 102 may apply a cell specific random access configuration corresponding to the selected RA type to perform the random access procedure. Herein, the UL BWP may be configured with 4-step random access resources and may or may not be 2-step random access resources.

[0238] Additionally or alternatively, in a case that the UL BWP is configured with random access resources for one RA type, the UE 102 may select this one RA type and corresponding random access resources to perform/initiate random access procedure. Herein, random access resources for one RA type may be one of 4-step random access resources, 4-step random access resources specific to RedCap UEs, 2-step random access resources, and 2-step random access resources specific to RedCap UEs.

[0239] Additionally or alternatively, in the example of the implementation, a RRC parameter included in the system information can be introduced to indicate the UE 102 whether the 2-step random access type is available or not for random access procedure. [0240] The UE 102 may receive, from the base station 160, the system information further including a third cell specific random access configuration wherein the third cell specific random access configuration is used for 2-step random access type. An RRC parameter included in the system information (or in the third cell specific random access configuration) is used to indicate whether the 2-step random access type is available or not for random access procedure for reduced capability (redcap) UEs for the UL BWP. [0241] In a case that the RRC parameter indicates the 2-step random access type is not available for random access procedure to RedCap UEs, the UE 102 may select a 4- step random access type for random access procedure.

[0242] On the other hand, in a case that the RRC parameter indicates the 2-step random access type is available for the random access procedure for redcap, the UE 102 may select one of the 4-step random access procedure and the 2-step random access procedure based on the RSRP of the downlink pathloss reference for the random access procedure. Additionally or alternatively, in this case, the UE 102 may select one of the 4-step random access procedure and the 2-step random access procedure based on whether random access resources specific to RedCap UEs are configured for the UL BWP.

[0243] In an example of the implementation, the UE 102 may first determine to select one type of the 4-step RA type and 2-step RA type based on the RSRP of the downlink pathloss reference and not based on whether random access resources specific to RedCap UEs are configured for the UL BWP. That is, regardless of whether random access resources specific to RedCap UEs is configured for which RA type, the UE 102 may first determine to select one type of the 4-step RA type and 2-step RA type based on the RSRP of the downlink pathloss reference. After selecting the RA type, the UE 102 may further determine 1106, based on whether random access resources specific to RedCap UEs are configured for the selected RA type for the UL BWP, to apply which cell specific random access configuration for the selected RA type to perform initialization of a random access resources. ‘Performing initialization of a random access resources’ may mean ‘Appling parameters as illustrated in the implementation 1000 for PRACH transmission or for random access resource selection ’.

[0244] In the present disclosure, as above-mentioned, the RRC parameters initialUplinkBWP may indicate the initial UL BWP configuration for a serving cell (e.g., a SpCell and Scell). The base station may transmit initialDownlinkBWP and/or initialUplinkBWP which may be included in SIB1, RRC parameter ServingCellConfigCommon, or RRC parameter ServingCellConfig to the UE. The RRC parameters initialUplinkBWP included in the SIB1 is used to indicate the initial UL BWP configuration for a primary cell. Additionally or alternatively, a RRC parameter initialUplinkBWP -redCap may be included in the SIB1 as well. The initialUplinkBWP - redCap can be used to indicate the initial UL BWP configuration for a primary cell. The initialUplinkBWP -redCap provides the initial UL BWP configuration specific to RedCap UEs for a primary cell. Either initialUplinkBWP and initialUplinkBWP- redCap may include generic parameters (e.g. locationAndBandwidth, subcarrierSpacing, cyclicPreflx) of the initial UL BWP, cell specific parameters (e.g. pucch-ConfigCommon) for PUCCH of the initial UL BWP, cell specific parameters (e.g. pusch-ConfigCommon) for the PUSCH of the initial UL BWP, and cell specific random access parameters (e.g. rach-ConfigCommon).

[0245] For operation on the primary cell, the base station 160 may configure a UE 102 with an initial UL BWP according to the initialUplinkBWP or initialUplinkBWP - redCap. For operation on the primary cell, a UE 102 is provided an initial UL BWP by initialUplinkBWP-redCap, if the initialUplinkBWP -redCap is configured (or is provided); Otherwise, the UE 102 is provided an initial UL BWP by initialUplinkBWP . To be specific, for operation on the primary cell, in a case that the SIB 1 includes the initialUplinkBWP-redCap, the UE 102 is provided an initial UL BWP by the initialUplinkBWP-redCap. In this case, the UE 102 may ignore the RRC parameter initialUplinkBWP included in the SIB1 and may apply initialUplinkBWP-redCap to determine the initial UL BWP. In other words, in a case that SIB1 includes the initialUplinkBWP -redCap, the UE 102 (i.e. RedCap UEs) may determine an initial UL BWP based on the initialUplinkBWP-redCap and may determine the initial UL BWP not based on the initialUplinkBWP. Non-RedCap UEs may determine the initial UL BWP based on the initialUplinkBWP. That is, the base station 160 may configure an initial UL BWP for non-RedCap UEs and configure another initial UL BWP for RedCap UEs separately from the initial UL BWP for non-RedCap UEs. RedCap UEs and non- RedCap UEs may not share a same UL BWP.

[0246] On the other hand, in a case that the SIB1 does not include the initialUplinkBWP-redCap and includes the initialUplinkBWP, the UE 102 is provided an initial UL BWP by the initialUplinkBWP. In this case, the UE 102 may apply initialUplinkBWP to determine the initial UL BWP. In other words, in a case that SIB1 does not include the initialUplinkBWP -redCap, the UE 102 may determine an initial UL BWP based on the initialUplinkBWP. On the other hand, non-Redcap UEs may apply initialUplinkBWP to determine the initial UL BWP and may not apply initialUplinkBWP-redCap to determine the initial UL BWP.

[0247] Therefore, if the initialUplinkBWP-redCap is included in the system information (e.g. SIB1), the UE 102 may consider or determine that (i)early indication of RedCap UEs is enabled for both 4-step RA type and 2-step RA type by the base station 160 in the UL BWP and/or (ii) random access resources specific to RedCap UEs or early indication of RedCap UEs are provided (or configured) in the UL BWP for 4- step RA type and 2-step RA type. Moreover, as above-mentioned, initial UL BWP configuration may include the cell specific random access configuration (parameters). Therefore, a cell specific random access configuration specific to RedCap UEs may be included in the initialUplinkBWP-redCap. That is, a cell specific random access configuration (e.g. rach-ConfigCommon-redCap or rach-ConfigCommon) included in the initialUplinkBWP-redCap is a cell specific random access configuration specific to RedCap UEs and is used for early indication of RedCap UEs. A cell specific random access configuration (e.g. rach-ConfigCommon-redCap, rach-ConfigCommon msgA- ConfigCommon-redCap or msgA-rach-ConfigCommon) included in the initialUplinkBWP-redCap configures cell specific random access parameters specific to RedCap UEs.

[0248] On the other hand, the base station may not configure the UE 102 with the initialUplinkBWP -redCap. That is, RedCap UEs and non-RedCap UEs are configured with a same UL BWP indicated by the initialUplinkBWP. RedCap UEs and non- RedCap UEs may share a same UL BWP. In this case, the initialUplinkBWP may include the rach-ConfigCommon (i.e. the first configuration) while the initialUplinkBWP may or may not include the rach-ConfigCommon-redCap (i.e. the second configuration). If the rach-ConfigCommon-redCap (i.e. the second configuration) is included in initialUplinkBWP, the UE 102 may consider or determine that (i) early indication of RedCap UEs is enabled for 4-step RA type by the base station 160 in the UL BWP and/or (ii) random access resources specific to RedCap UEs or early indication of RedCap UEs are provided (or configured) in the UL BWP for 4-step RA type. If the rach-ConfigCommon-redCap is not included in initialUplinkBWP, i.e. the second configuration is not provided, the UE 102 may consider or determine that (i) early indication of RedCap UEs is disabled for 4-step RA type by the base station 160 in the UL BWP and/or (ii)random access resources specific to RedCap UEs or early indication of RedCap UEs are not provided (or configured) in the UL BWP for 4-step RA type.

[0249] Additionally or alternatively, the initialUplinkBWP may include the msgA- ConfigCommon (i.e. the third configuration) while the initialUplinkBWP may or may not include the msgA-ConfigCommon-redCap (i.e. the fourth configuration). If the msgA-ConfigCommon-redCap (i.e. the fourth configuration) is included in initialUplinkBWP, the UE 102 may consider or determine that (i) early indication of RedCap UEs is enabled for 2-step RA type by the base station 160 in the UL BWP and/or (ii) random access resources specific to RedCap UEs or early indication of RedCap UEs are provided (or configured) in the UL BWP for 2-step RA type. If the msgA-ConfigCommon-redCap is not included in initialUplinkBWP, i.e. the fourth configuration is not provided, the UE 102 may consider or determine that (i) early indication of RedCap UEs is disabled for 4-step RA type by the base station 160 in the UL BWP and/or (ii) random access resources specific to RedCap UEs or early indication of RedCap UEs are not provided (or configured) in the UL BWP for 4-step RA type.

[0250] According to above-mentioned implementations of the present disclosure, different cell specific random access configurations provide separate random access resources for random access procedure. As above-mentioned, the first cell specific random access configuration and the second cell specific random access configuration may provide common configuration of PRACH occasions. ‘Common configuration of PRACH occasions’ means PRACH occasions are shared by the first cell specific random access configuration and the second cell specific configuration. In a shared PRACH occasion, preambles associated with a SS/PBCH block configured by the first cell specific random access configuration should be different from those associated with the SS/PBCH configured by the second cell specific random access configuration. Solutions on how to determine preambles configured by the first cell specific random access configuration and preambles configured by the second sell specific random access configuration are illustrated below to provide a flexible and efficient communication.

[0251] Figure 12 is a flow diagram illustrating one implementation of a method 1200 for determining preambles configured by different cell specific random access configurations by a UE 102. In the implementation of the present disclosure, different cell specific random access configurations may corresponds to the first cell specific random access configuration and the second cell specific random access configuration as specified in the above-mentioned implementations 1000 and/or 1100.

[0252] The UE 102 may receive 1202, from a base station 160, system information including a first cell specific random access configuration (e.g., rach-ConfigCommon) for an UL BWP. The description of the first cell specific random access configuration illustrated in above implementations 1000 and/or 1100 can equally apply to the description of the first cell specific random access configuration in the implementation 1200. The first cell specific random access configuration includes a first RRC parameter (e.g. ssb-perRACH-OccasionAndCB-PreamblesPerSSB) and a second RRC parameter (e.g. totalNumberOfRA-Preambles) wherein the first RRC parameter indicates a first value of SS/PBCH blocks per PRACH occasion and a second value of contention based preambles per SS/PBCH block, and the second RRC parameter (e.g. totalNumberOfRA- Preambles) indicates a third value of a total number of contention based preambles and contention free preambles per PRACH occasion. The total number of contention based preambles and contention free preambles per PRACH occasion excludes preambles used for other purposes, for example, for system information request. In a case that the second RRC parameter is not included in the first cell specific random access configuration, the third value is equal to 64. That is, all 64 preambles in a PRACH occasion are available for random access.

[0253] The UE 102 may receive 1204, from a base station 160, system information including a second cell specific random access configuration (e.g., rach- ConfigCommon-redcap) for the UL BWP. The description of the second cell specific random access configuration illustrated in above implementations 1000 and/or 1100 can equally apply to the description of the second cell specific random access configuration in the implementation 1200. The second cell specific random access configuration includes a third RRC parameter wherein the third RRC parameter indicates a fourth value of preamble starting position. The fourth value may be commonly used to determine set of contention based preambles for each SS/PBCH block. The second cell specific random access configuration includes a fourth RRC parameter wherein the fourth RRC parameter indicates a fifth value of contention based preambles per SS/PBCH block. [0254] The first cell specific random access configuration and the second cell specific random access configuration may provide common configuration of PRACH occasions. That is, in the UL BWP, the time and frequency locations of the PRACH occasions configured by the first cell specific random access configuration are as same as those of the PRACH occasions configured by the second cell specific random access configuration. In other words, the PRACH occasions configured by the first cell specific random access configuration overlap with the PRACH occasions configured by the second cell specific random access configuration in the time and frequency domain in the UL BWP.

[0255] In a shared or overlapped PRACH occasion, preambles provided by the first cell specific random access configuration for a SS/PBCH block with index n are different from those provided by the second cell specific random access configuration for the SS/PBCH block with index n. That is, in the implementation, shared PRACH occasions but separate preambles are configured by the first cell specific random access configuration and the second cell specific random access configuration.

[0256] The UE 102 and/or the base station 160 may determine 1206, in a PRACH occasion, sets of contention based preambles associated with the SS/PBCH block with index n for the first cell specific random access configuration and the second cell specific random access configuration, respectively. The PRACH occasion herein is a PRACH occasion associated with the SS/PBCH block with index n. A set of contention based preambles is a set of contention based preambles with consecutive indexes associated with a SS/PBCH block configured by corresponding cell specific random access configuration. Therefore, in a PRACH occasion associated with a SS/PBCH block with index n, the UE 102 and/or the base station 160 may determine 1206 a first set of contention based preambles based on the first cell specific random access configuration and determine a second set of contention based preambles based on the first cell specific random access configuration and the second specific random access configuration wherein both the first set of contention based preambles and the second set of contention based preambles are associated with the SS/PBCH block with index n.

[0257] In other words, the first set of contention based preambles is configured by or used for the first cell specific random access configuration while the second set of contention based preambles is configured by or used for the second cell specific random access configuration. ‘Determining a set of contention based preambles’ may include ‘determining a preamble index of the first preamble within the set of contention based preambles’ and/or ‘determine a total number of contention based preambles within the set’. In the implementation of the present disclosure, the first cell specific RA configuration and the second cell specific RA configuration provide common configuration of PRACH occasions.

[0258] Figure 13 is a diagram illustrating some examples 1300-1 and 1300-2 for determining preambles configured by different cell specific random access configurations by a UE 102.

[0259] In an example of the implementation, the first value is equal to or larger than 1. The UE 102 and/or the base station 160 may determine the second set of contention based preambles associated with a SS/PBCH block with index n per PRACH occasion configured by the second cell specific RA configuration, wherein a first preamble index within the set is determined based on the index n, the first value, the third value, the fourth value and not based on the second value in a case the first cell specific RA configuration and the second cell specific RA configuration provide common configuration of PRACH occasions and the first value is equal to or larger than 1.

[0260] In Figure 13 A, there are 64 preambles defined for a PRACH occasion 1310. The second RRC parameter (e.g. totalNumberOfRA-Preambles) indicates a third value 1311 of a total number of contention based preambles and contention free preambles per PRACH occasion. Herein the third value is equal to 60. The remaining 4 preambles in 1309 can be used for other purpose, for example, system information request. The first value is equal to 2. That is, there are two SS/PBCH blocks mapped to one PRACH occasion. In the Figure 13 A, SS/PBCH block with index 0 and SS/PBCH block with index 1 are mapped to one same PRACH occasion. The set of contention based preambles 1301 is associated with SS/PBCH block with index 0. The set of contention based preambles 1303 is associated with SS/PBCH block with index 0. The set of contention based preambles 1305 is associated with SS/PBCH block with index 1. The set of contention based preambles 1307 is associated with SS/PBCH block with index 1. A total number of contention based preambles within the set 1301 is equal to the second value. A total number of contention based preambles within the set 1305 is equal to the second value. A total number of contention based preambles within the set 1303 is equal to the fifth value. A total number of contention based preambles within the set 1307 is equal to the fifth value. As above-mentioned, the set 1301 and the set 1305 are configured by or used for the first cell specific random access configuration. The set 1303 and the set 1307 are configured by or used for the second cell specific random access configuration. The contention based preambles within the set 1303 and the set 1307 are specific to RedCap UEs.

[0261] In Figure 13 A, the UE 102 and/or the base station 160 may determine the preamble index of a first preamble within a set (i.e. the set 1301 and the set 1305) associated with a SS/PBCH block with index n based on the index n, the first value and the third value. To be specific, the preamble index of the first preamble (i.e. the first preamble index) within a set associated with a SS/PBCH block with index n can be determined as n × N ^total _preamble / N where the first value is denoted as N and the third value is denoted as N ^total _preamble . In Figure 13 A, the preamble index of the first preamble within the set 1301 is determined as 0 while the preamble index of the first preamble within the set 1305 is determined as 30.

[0262] In Figure 13 A, the UE 102 and/or the base station 160 may determine the preamble index of a first preamble within a set (i.e. the set 1303 and the set 1307) associated with a SS/PBCH block with index n based on the index n, the first value, the third value and the fourth value and not based on the second value. To be specific, the preamble index of the first preamble (i.e. the first preamble index) within a set associated with a SS/PBCH block with index n can be determined as n × N ^total _preamble /N+S where the first value is denoted as N, the third value is denoted as N ^total _preamble , and the fourth value is denoted as S. In Figure 13 A, the preamble index of the first preamble within the set 1303 is determined as S while the preamble index of the first preamble within the set 1307 is determined as 30+S.

[0263] In Figure 13A, sets of preambles as like 1302, 1304, 1306 and 1308 can be configured by the base station 160 to be used for other functionalities. For example, the sets of preambles as like 1302 and 1306 can be used for above-mentioned 2-step RA type. In current specification 38.213, the set of 2-step CBRA preambles for a SS/PBCH block with index n starts from the end of the 4-step CBRA preambles for the same SS/PBCH block with index n. That is, the preamble index of the first preamble within the set of 2-step CBRA preambles for a SS/PBCH block with index n is determined based on the second value. [0264] In an example of the implementation, the first value is less than 1. The UE 102 and/or the base station 160 may determine the second set of contention based preambles associated with a SS/PBCH block with index n per PRACH occasion configured by the second cell specific RA configuration, wherein a first preamble index within the set is determined based on the fourth value and not based on the second value in a case the first cell specific RA configuration and the second cell specific RA configuration provide common configuration of PRACH occasions and the first value is less than 1.

[0265] In Figure 13B, there are 64 preambles defined for a PRACH occasion 1326. The second RRC parameter (e.g. totalNumberOfRA-Preambles) indicates a third value 1327 of a total number of contention based preambles and contention free preambles per PRACH occasion. Herein the third value is equal to 60. The remaining 4 preambles in 1325 can be used for other purpose, for example, system information request. The first value is equal to 1/2. That is, one SS/PBCH block is mapped to two consecutive PRACH occasions. In the Figure 13B, SS/PBCH block with index 0 is mapped to the PRACH occasion. The set of contention based preambles 1321 is associated with SS/PBCH block with index 0. The set of contention based preambles 1323 is associated with SS/PBCH block with index 0. A total number of contention based preambles within the set 1321 is equal to the second value. A total number of contention based preambles within the set 1323 is equal to the fifth value. As above-mentioned, the set 1321 is configured by or used for the first cell specific random access configuration. The set 1323 is configured by or used for the second cell specific random access configuration. The contention based preambles within the set 1323 are specific to RedCap UEs.

[0266] In Figure 13B, the UE 102 and/or the base station 160 may determine the preamble index of a first preamble within a set (i.e. the set 1321) associated with a SS/PBCH block with index n starting from preamble index 0.

[0267] In Figure 13B, the UE 102 and/or the base station 160 may determine the preamble index of a first preamble within a set (i.e. the set 1323) associated with a SS/PBCH block with index n based on the fourth value and not based on the second value. To be specific, the preamble index of the first preamble (i.e. the first preamble index) within a set associated with a SS/PBCH block with index n can be determined as S where the fourth value is denoted as S. In Figure 13B, the preamble index of the first preamble within the set 1323 is determined as S.

[0268] In Figure 13B, sets of preambles as like 1322 and 1324 can be configured by the base station 160 to be used for other functionalities. For example, the sets of preambles as like 1322 can be used for above-mentioned 2-step RA type. In current specification 38.213, the set of 2-step CBRA preambles for a SS/PBCH block with index n starts from the end of the 4-step CBRA preambles for the same SS/PBCH block with index n. That is, the preamble index of the first preamble within the set of 2-step CBRA preambles for a SS/PBCH block with index n is determined based on the second value.

[0269] In above various implementations of the present disclosure, the second cell specific random access configuration and/or the fourth cell specific random access configuration may be also used for a kind of service or a kind of functionality or a kind of feature. For example, the second configuration and/or the fourth configuration can be used for indication of need of Msg3 initial repetition transmission, or for indication of small data transmission (SDT) to request a larger Msg3 size, or for indication of RAN slicing to indicate high priority slice to the base station. Additionally or alternative, the second configuration and/or the fourth configuration can be used a combination feature of one, more or all of the indication of need of Msg3 initial repetition transmission, or for indication of small data transmission, or for indication of RAN slicing, or for indication of reduced capabilities (RedCap).

[0270] Figure 14 illustrates various components that may be utilized in a UE 1402. The UE 1402 (UE 102) described in connection with Figure 14 may be implemented in accordance with the UE 102 described in connection with Figure 1. The UE 1402 includes a processor 1481 that controls operation of the UE 1402. The processor 1481 may also be referred to as a central processing unit (CPU). Memory 1487, which may include read-only memory (ROM), random access memory (RAM), a combination of the two or any type of device that may store information, provides instructions 1483a and data 1485a to the processor 1481. A portion of the memory 1487 may also include non-volatile random access memory (NVRAM). Instructions 1483b and data 1485b may also reside in the processor 1481. Instructions 1483b and/or data 1485b loaded into the processor 1481 may also include instructions 1483a and/or data 1485a from memory 1487 that were loaded for execution or processing by the processor 1481. The instructions 1483b may be executed by the processor 1481 to implement one or more of the methods 200 described above.

[0271] The UE 1402 may also include a housing that contains one or more transmitters 1458 and one or more receivers 1420 to allow transmission and reception of data. The transmitter(s) 1458 and receiver(s) 1420 may be combined into one or more transceivers 1418. One or more antennas 1422a-n are attached to the housing and electrically coupled to the transceiver 1418.

[0272] The various components of the UE 1402 are coupled together by a bus system 1489, which may include a power bus, a control signal bus and a status signal bus, in addition to a data bus. However, for the sake of clarity, the various buses are illustrated in Figure 14 as the bus system 1489. The UE 1402 may also include a digital signal processor (DSP) 1491 for use in processing signals. The UE 1402 may also include a communications interface 1493 that provides user access to the functions of the UE 1402. The UE 1402 illustrated in Figure 14 is a functional block diagram rather than a listing of specific components.

[0273] Figure 15 illustrates various components that may be utilized in a base station 1560. The base station 1560 described in connection with Figure 15 may be implemented in accordance with the base station 160 described in connection with Figure 1. The base station 1560 includes a processor 1581 that controls operation of the base station 1560. The processor 1581 may also be referred to as a central processing unit (CPU). Memory 1587, which may include read-only memory (ROM), random access memory (RAM), a combination of the two or any type of device that may store information, provides instructions 1583a and data 1585a to the processor 1581. A portion of the memory 1587 may also include non-volatile random access memory (NVRAM). Instructions 1583b and data 1585b may also reside in the processor 1581. Instructions 1583b and/or data 1585b loaded into the processor 1581 may also include instructions 1583a and/or data 1585a from memory 1587 that were loaded for execution or processing by the processor 1581. The instructions 1583b may be executed by the processor 1581 to implement one or more of the methods 300 described above.

[0274] The base station 1560 may also include a housing that contains one or more transmitters 1517 and one or more receivers 1578 to allow transmission and reception of data. The transmitter(s) 1517 and receiver(s) 1578 may be combined into one or more transceivers 1576. One or more antennas 1580a-n are attached to the housing and electrically coupled to the transceiver 1576.

[0275] The various components of the base station 1560 are coupled together by a bus system 1589, which may include a power bus, a control signal bus and a status signal bus, in addition to a data bus. However, for the sake of clarity, the various buses are illustrated in Figure 15 as the bus system 1589. The base station 1560 may also include a digital signal processor (DSP) 1591 for use in processing signals. The base station 1560 may also include a communications interface 1593 that provides user access to the functions of the base station 1560. The base station 1560 illustrated in Figure 15 is a functional block diagram rather than a listing of specific components.

[0276] The term “computer-readable medium” refers to any available medium that can be accessed by a computer or a processor. The term “computer-readable medium,” as used herein, may denote a computer- and/or processor-readable medium that is non- transitory and tangible. By way of example, and not limitation, a computer-readable or processor-readable medium may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer or processor. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers.

[0277] It should be noted that one or more of the methods described herein may be implemented in and/or performed using hardware. For example, one or more of the methods described herein may be implemented in and/or realized using circuitry, a chipset, an application-specific integrated circuit (ASIC), a large-scale integrated circuit (LSI) or integrated circuit, etc.

[0278] Each of the methods disclosed herein comprises one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another and/or combined into a single step without departing from the scope of the claims. In other words, unless a specific order of steps or actions is required for proper operation of the method that is being described, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. [0279] It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the systems, methods and apparatus described herein without departing from the scope of the claims.