[Title of Invention]

USER EQUIPMENT, BASE STATION, AND METHOD [Technical Field]

[0001] The present disclosure relates to a terminal apparatus, a base station apparatus, a communication method, and an integrated circuit.

[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 (3GPP).

[0003] In the fifth generation cellular system, three services of enhanced Mobile BroadBand (eMBB) to achieve high-speed and large-volume transmission, Ultra-Reliable 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 (IoT) have been demanded as assumed scenarios. [0004] For example, wireless communication devices may communicate with one or more devices for multiple service types. However, current existing systems and methods may only offer limited flexibility and efficiency for multiple service communication. As illustrated by this discussion, systems and methods according to the prevent invention, supporting multiple search space configuration and/or DCI alignment, may improve communication flexibility and efficiency and may 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 search space configuration and/or DCI alignment may be implemented; [0006] Figure 2 is a diagram illustrating a RRC parameter SearchSpace with an information element structure A 200;

[0007] Figure 3 is a diagram illustrating a RRC parameter SearchSpace-v16 with an information element structure B 300;

[0008] Figure 4 is a diagram illustrating a RRC parameter SearchSpace-v16 with an information element structure C 400;

[0009] Figure 5 is a flow diagram illustrating one implementation of a method 500 for search for PDCCH candidates by a UE 102.

[0010] Figure 6 is a flow diagram illustrating one implementation of a method 600 for search for PDCCH candidates by a base station 160;

[0011] Figure 7 is a diagram illustrating one example 700 how to determine PDCCH monitoring occasions for PDCCH candidates based on a received RRC parameter(s) related to search space configuration.

[0012] Figure 8 is a flow diagram illustrating one implementation of a method 800 for DCI size alignment operation by a UE 102.

[0013] Figure 9 is a flow diagram illustrating one implementation of a method 900 for DCI size alignment operation by a base station 160.

[0014] Figure 10 illustrates various components that may be utilized in a UE;

[0015] Figure 11 illustrates various components that may be utilized in a base station;

[Description of Embodiments]

[0016] A method by a user equipment (UE) is described. The method includes receiving, from a base station, a first radio resource control (RRC) parameter with a first information element structure to define the UE to search for PDCCH candidates for a first DCI format, receiving a second RRC parameter with a second information element structure to define the UE to search for PDCCH candidates for a second DCI format, receiving a third RRC parameter with the first information element structure to define the UE to search for PDCCH candidates for a third DCI format. The first information element structure is capable of indicating that the search space is a common search space or a UE-specific search space. The second information element structure is not capable of indicating that the search space is a common search space. The first DCI format, the second DCI format, and the third DCI format can be configured to be monitored in UE-specific search space. The first DCI format and the second DCI format cannot be configured to be monitored in common search space. The third DCI format can be configured to be monitored in common search space.

[0017] A method by a base station is described. The method includes transmitting, to a user equipment (UE), a first radio resource control (RRC) parameter with a first information element structure to define the UE to search for PDCCH candidates for a first DCI format, transmitting a second RRC parameter with a second information element structure to define the UE to search for PDCCH candidates for a second DCI format, transmitting a third RRC parameter with the first information element structure to define the UE to search for PDCCH candidates for a third DCI format. The first information element structure is capable of indicating that the search space is a common search space or a UE-specific search space. The second information element structure is not capable of indicating that the search space is a common search space. The first DCI format, the second DCI format, and the third DCI format can be configured to be monitored in UE-specific search space. The first DCI format and the second DCI format cannot be configured to be monitored in common search space. The third DCI format can be configured to be monitored in common search space.

[0018] A user equipment (UE) is described. The UE includes reception circuitry configured to receive, from a base station, a first radio resource control (RRC) parameter with a first information element structure to define the UE to search for PDCCH candidates for a first DCI format, to receive a second RRC parameter with a second information element structure to define the UE to search for PDCCH candidates for a second DCI format, to receive a third RRC parameter with the first information element structure to define the UE to search for PDCCH candidates for a third DCI format. The first information element structure is capable of indicating that the search space is a common search space or a UE-specific search space. The second information element structure is not capable of indicating that the search space is a common search space. The first DCI format, the second DCI format, and the third DCI format can be configured to be monitored in UE-specific search space. The first DCI format and the second DCI format cannot be configured to be monitored in common search space. The third DCI format can be configured to be monitored in common search space. [0019] A base station is described. The base station includes transmission circuitry configured to transmit, to a user equipment (UE), a first radio resource control (RRC) parameter with a first information element structure to define the UE to search for PDCCH candidates for a first DCI format, to transmit a second RRC parameter with a second information element structure to define the UE to search for PDCCH candidates for a second DCI format, to transmit a third RRC parameter with the first information element structure to define the UE to search for PDCCH candidates for a third DCI format. The first information element structure is capable of indicating that the search space is a common search space or a UE-specific search space. The second information element structure is not capable of indicating that the search space is a common search space. The first DCI format, the second DCI format, and the third DCI format can be configured to be monitored in UE-specific search space. The first DCI format and the second DCI format cannot be configured to be monitored in common search space. The third DCI format can be configured to be monitored in common search space.

[0020] 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).

[0021] At least some aspects of the systems and methods disclosed herein may be described in relation to the 3GPP 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, and/or 15, 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.

[0022] 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, 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 3 GPP standards, the terms “UE” and “wireless communication device” may be used interchangeably herein to mean the more general term “wireless communication device.” [0023] 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.

[0024] 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.

[0025] “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. [0026] 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 SI 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 Sl- MME interface and to the serving gateway (S-GW) by the Sl-U interface. The SI interface supports a many-to-many relation between MMEs, serving gateways and the base stations. The SI -MME interface is the SI interface for the control plane and the Sl-U interface is the S 1 interface for the user plane. The Uu interface is a radio interface between the UE and the base station for the radio protocol.

[0027] 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.

[0028] 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-fDLE and security control.

[0029] 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. SRBO may be used for RRC messages using the common control channel (CCCH) logical channel. SRBl 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 SRBl 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.

[0030] 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.

[0031] System information may be divided into the MasterlnformationBlock (MIB) and a number of SystemlnformationB locks (SIBs).

[0032] 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.

[0033] 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).

[0034] 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). [0035] 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.

[0036] 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. Re establishment 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.

[0037] 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).

[0038] 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.

[0039] The systems and methods described herein may enhance the efficient use of radio resources in Carrier aggregation 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). [0040] 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.

[0041] 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.

[0042] 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 S 1 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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;

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.

[0047] The size of various fields in the time domain is expressed in time units The constant where

[0048] Multiple OFDM numerologies are supported as given by Table 4.2-1 of

[TS 38.211] where and the cyclic prefix for a bandwidth part are obtained from the higher-layer parameter subcarrierSpacing and cyclicPrefix, respectively.

[0049] The size of various fields in the time domain may be expressed as a number of time units seconds. Downlink and uplink transmissions are organized into frames with duration, each consisting often 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.

[0050] For subcarrier spacing configuration , 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 . 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.

[0051] 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].

[0052] 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.

[0053] 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.

[0054] 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 search space configuration (or search for PDCCH candidates) and/or DCI size alignment 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.

[0055] 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.

[0056] 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. Examples of downlink signals include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a cell-specific reference signal (CRS), a non-zero 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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. [0061] 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 DCI 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 an Radio Resource Control (RRC) entity. For example, the UE RRC information configuration module 126 may process RRC parameter for search space configurations with different information element structures. The UE DCI control module 128 may determine when and where to monitor or search the configured PDCCH candidates for each search space set based on the processing output from the UE RRC information configuration module 126. The UE DCI control module 128 may further perform a DCI size alignment operation to determine a DCI size of the configured DCI format according to configured conditions.

[0062] The UE operations module 124 may provide the benefit of performing PDCCH candidate search and monitoring efficiently.

[0063] 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.

[0064] 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.

[0065] 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 anticipated PDCCH candidate encoding with which DCI size for transmissions from the base station 160.

[0066] 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.

[0067] 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. [0068] 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.

[0069] 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.

[0070] 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. [0071] 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.

[0072] 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 payload 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.

[0073] 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 DCI control module 196. The base station operations module 182 may include PHY entities, MAC entities, RLC entities, PDCP entities, and an RRC entity. For example, the base station operation module 196 may determine, for UE(s), when and where to monitor or search the configured PDCCH candidates for each search space set.

[0074] The base station RRC information configuration module 194 may generate RRC parameters for search space configurations with different information element structures based on the output from the base station DCI control module 196. The UE DCI control module 196 may further perform a DCI size alignment operation to determine a DCI size of the configured DCI format according to configured conditions. [0075] The base station operations module 182 may provide the benefit of performing PDCCH candidate search and monitoring efficiently.

[0076] 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).

[0077] 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. [0078] 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.

[0079] 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. [0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] A PDCCH may consist of one or more control channel elements (CCEs). A CCE may consist of 6 resource element groups (REGs). A REG may equal one resource block during one OFDM symbol. 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. A UE may monitor a set of PDCCH candidates in one or more control Resource set (CORESET) on an active DL BWP on an activated cell. Monitoring means decoding each PDCCH candidate according to the monitored DCI formats.

[0086] A set of PDCCH candidates for a UE to monitor is defined in terms of PDCCH search space sets. A PDCCH candidate for a search space set s may correspond to a set of CCEs in a CORESET associated with the search space set s. In the present disclosure, the term “PDCCH search space sets” may also refer to “PDCCH search space”. In the present disclosure, the term “search space sets” may also refer to “search space”. AUE 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. In other words, a UE can determine the CCE indexes for aggregation level L corresponding to PDCCH candidates of a USS for a USS set based on the value of C-RNTI addressed to the UE. The UE can determine the CCE indexes for aggregation level L corresponding to PDCCE1 candidates of a CSS for a CSS set without the value of C-RNTI addressed to the UE.

[0087] 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).

[0088] A base 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. [0089] 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’.

[0090] 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.

[0091] 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 ULBWP) 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. [0092] 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.

[0093] 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.

[0094] 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 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 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 initial UplinkB WP.

[0095] 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.

[0096] A base station may transmit a RRC message including one or more RRC parameters related to CORESET configuration. 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 DLBWP configuration may also include the RRC parameter ControlResourceSetZero. A RRC parameter ControlResourceSet is used to configure a time and frequency CORESET other than CORESET 0. A RRC parameter ControlResourceSetld included in the ControlResourceSet is CORESET index, used to identify a CORESET within a serving cell.

[0097] 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, or SearchSpace-v 16) defines how and where to search for PDCCH candidates. The RRC RRC parameter(s) related to search space configuration (e.g. SearchSpace, SearchSpace-v 16) may have different information element structures ‘search/monitor for PDCCH candidate for a DCI format’ may also refer to ‘monitor/search for a DCI format’ for short.

[0098] Figure 2 is a diagram illustrating a RRC parameter (RRC information) SearchSpace with an information element structure A 200.

[0099] The RRC parameter SearchSpace with an information element structure A is related to search space configuration. As depicted in Figure 2, the RRC parameters search space may include a plurality of RRC parameters as like, searchSpaceld, ControlResourceSetld, monitoringSlotPeriodicityAndOffset, duration, monitor ingSymbolsWithinSlot, 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.

[0100] Here, 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).

[0101] The RRC parameter may include aggregationLevel1, aggregationLevel2, aggregationLevel4, aggregationLevel8, aggregationLevel16. The RRC parameter nrofCandidates may provide a number of PDCCH candidates per CCE aggregation level L by aggregationLevell , aggregationLevel2, aggregationLevel4, aggregationLevel8, and aggregationLevel16, 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. [0102] 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.

[0103] 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.

[0104] As above-mentioned, the RRC parameter SearchSpace with information element structure A is capable of indicating that the search space set s is a CSS (e.g. a CSS set) or a USS (e.g. a USS set). A base station may configure a UE to whether monitor PDCCH candidates for DCI format 0 0 and DCI format 1_0, or for DCI format 0_1 and DCI format 1_1 in a USS set via the RRC parameter SearchSpace with information element structure A. That is, the base station may not configure a UE to monitor PDCCH candidates for a different DCI format(s) other than the existing DCI format(s) {DCI format 0 0, DCI format 1_0, DCI format 0 1, DCI format 1_1 } in the USS set via the RRC parameter SearchSpace with information element structure A. In other words, the UE may, based on the received RRC parameter SearchSpace from the base station, 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 a USS. The UE may be not be configured to monitor PDCCH candidates for a different DCI format(s) other than the existing DCI format(s) {DCI format 0 0, DCI format 1_0, DCI format 0_1, DCI format 1_1} in the USS. [0105] Communication with new service traffic type like (but not limited to) URLLC may require new DCI format(s) design other than the existing DCI formats. For example, some new fields may be introduced in a new DCI format to implement different communication features. For example, some fields included in the existing DCI formats may be not necessary any more to adapt different communication features. In order to implement communication feature with different service traffic types, different DCI formats may be generated according to different service traffic types. Introduction of new DCI format(s) other than the existing DCI formats would be beneficial and efficient for communication with a new service traffic type like URLLC between based station(s) and UE(s). Hence, the RRC parameter SearchSpace with current information element structure A may be problematic, which is incapable of indicating a new DCI format. It would be beneficial to introduce a RRC parameter related to search space configuration with a new information element structure so that the base station may indicate/configure a UE to monitor PDCCH candidates for new DCI format(s) other than the existing DCI formats in a USS.

[0106] Figure 3 is a diagram illustrating a RRC parameter SearchSpace-v16 with an information element structure B 300.

[0107] The RRC parameter SearchSpace-v16 with an information element structure B is related to search space configuration. As one example 302, the RRC parameter SearchSpace-v16 with an information element structure B may include a plurality of RRC parameters as like, searchSpaceld, controlResourceSetld, monitoringSlotPeriodicityAndOffset, duration, monitoringSymbolsWithinSlot, nr of Candidates, searchSpaceType . Some of the above-mentioned RRC parameters may be present or absent in the RRC parameters SearchSpace-v16 The searchSpaceType- v16 included in RRC parameter SearchSpace-v16 with an information element structure B may be different from the searchSpaceType included in the RRC parameter SearchSpace with information element structure A. The searchSpaceType-v16 may only indicate that the search space set s is a USS set. The searchSpaceType-v16 may not be used to indicate that the search space set s is a CSS set. The RRC parameter SearchSpace Type-v16 may include ue-Specific. The RRC parameter searchSpaceType- v16 may not include common. The RRC parameter searchSpaceType-v16 may also include dci-Format-v16. The dci-Format-v16 may be used to indicate whether the UE monitors PDCCH candidates in the USS for DCI formats 0_0 and 1 _ 0, or for DCI formats 0_2 and 1_2. That is, the dci-Format-v16 may be used to indicate which for DCI formats 0_0 and 1_0, or for DCI formats 0_2 and 1 2, the UE monitors PDCCH candidates in the USS. Additionally or alternatively, the dci-Format-v16 may be used to indicate which for DCI formats 0 0 and 1 0, or for DCI formats 0 1 and 1 _ 1, or for

DCI formats 0_2 and 1 2, the UE monitors PDCCH candidates in the USS. Additionally or alternatively, the dci-Format-v16 may be used to indicate which for DCI formats 0 2, or for DCI format 1_2, the UE monitors PDCCH candidates in the USS. Additionally or alternatively, the RPC parameter searchSpaceType-v 16 may not include a RRC parameter (e.g. dci-Format-v 16 ). That is, if a USS is configured/provided by the RRC parameter SearchSpace-v16, the UE may implicitly determine to monitor PDCCH candidates in the USS for DCI formats 0 2 and/or 1_2. [0108] As one example 304, the RRC parameter SearchSpace-v16 with an information element structure B may include a RRC parameter ue-Specific-v16. The ue-Specific-v16 is used to configure the search space as a USS set. The RRC parameter SearchSpace-v16 with an information element structure B may not include a RRC parameter common which is used to configure a search space set s as a CSS set. The RRC parameter ue-Specific-v16 may include a RRC parameter formats0-2-And-l -2. The RRC parameter formatsO-2-And-l -2 may configure a UE to monitor PDCCH candidates in the USS set for DCI format 0_2 and DCI format 1_2. Additionally or alternatively, the RRC parameter formats0-2-And-l -2 may configure a UE to monitor PDCCH candidates in the USS set for DCI format 0 2 or for DCI format 1_2.

[0109] As described in both 302 and 304, the RRC parameter SearchSpace-v16 with an information element structure B is not capable of indicating that the search space set s is a CSS (e.g. a CSS set). The RRC parameter SearchSpace-v16 with an information element structure B is capable of indicating that the search space set s is a USS. As described in 202, the RRC parameter SearchSpace with an information element structure A is capable of indicating that the search space set s is a CSS (e.g. a CSS set) or a USS (e.g. a USS set).

[0110] Figure 4 is a diagram illustrating a RRC parameter SearchSpace-v16 with an information element structure C 400.

[0111] The RRC parameter SearchSpace-v 16 with an information element structure C is related to search space configuration. As depicted in 402, the RRC parameter SearchSpace-v 16 with an information element structure C may include a RRC parameter searchSpaceType-v16. The RRC parameters common , ue-Specific, ue- Specific-v16 included in searchSpaceType-v16, may be used to indicate that the search space set s is a CSS set, a USS set A, or a USS set B, respectively. The USS set A ( ue- Specific ) may indicate whether a UE monitor for DCI formats 0_0 and 1_0 or for DCI formats 0_1 and 1_1 in the USS set A. A RRC parameter nrofCandidates-v 16, which may be included in SearchSpace-v 16 but may not be included in ue-Specific, may provide a number of PDCCH candidates per CCE aggregation level L for DCI formats 0_0 and 1_0 or for DCI formats 0_1 and 1_1. The USS set B (ue-Specific-v16) may indicate that a UE may monitor for DCI formats 0_2 and 1_2 in the USS set. Furthermore, the ue-Specific-v16 may further include a RRC parameter nrofCandidates-v 16 which may provide a number of PDCCH candidates per CCE aggregation level L for DCI formats 0_2 and 1 2. Hence, The RRC parameter SearchSpace-v 16 with an information element structure C is capable of indicating that a search space set is a CSS set, a first USS set (USS set A), or a second USS set (USS set B). The CSS set ( common ) may indicate that a UE may monitor for DCI formats 0 0 and 1 0 in the CSS set.

[0112] According to another example, a RRC parameter searchSpaceType-v16 in 402 may include either a common or a ue-Specific and but may not include ue-Specific- v16. In this case, the RRC parameter dci-Formats included in ue-Specific may indicate whether a UE may monitor PDCCH candidates for DCI format 0_0 and DCI format 1_0, or for DCI format 0_1 and DCI format 1 1, or for DCI format 0_2 and DCI format 1_2 in the USS set. Furthermore, in a case that dci-Formats indicates a UE to monitor PDCCH candidates for DCI format 0 2 and DCI format 1_2, the dci-Formats may further include a RRC parameter nrofCandidates-v 16 which may provide a number of PDCCH candidates per CCE aggregation level L for the DCI format 0_2 and DCI format 1_2. Otherwise, the RRC parameter nrofCandidates-v 16 may be absent in the dci-Formats.

[0113] The RRC parameters as like searchSpaceld, controlResourceSetld, monitoringSlotPeriodicityAndOffset, duration, monitor ingSymbolsWithinSlot, nrofCandidates in 302, 304, and 402 may have same usage as those in 202. Some of the above-mentioned RRC parameters may be present or absent in the RRC parameters SearchSpace-v 16. [0114] Figure 5 is a flow diagram illustrating one implementation of a method 500 for search for PDCCH candidates by a UE 102.

[0115] The UE 102 may receive 502, from the base station 160, a RRC message including one or more RRC parameter(s). At 502, the UE 102 may receive, from the base station 160, a RRC message including a first RRC parameter (e.g. SearchSpace ) with a first information element structure (e.g. information element structure A). At 502, the UE 102 may receive, from the base station 160, a RRC message including a third RRC parameter (e.g. SearchSpace ) with a first information element structure (e.g. information element structure A). At 502, the UE 102 may receive, from the base station 160, the RRC message further including a second RRC parameter (e.g. SearchSpace- v16) with a second information element structure (e.g. information element structure B or C). In other words, the first RRC parameter and the second parameter may be constructed by different information elements structure. The first RRC parameter and the second RRC parameter can be used to configure a search space set s, respectively. The first RRC parameter, the second parameter and the third parameter, which are related to search space set configuration, define the UE 102 how or where to search for PDCCH candidates. The first RRC parameter, the second RRC parameter and the third RRC parameter may include one or more above-mentioned parameters, respectively. [0116] The first RRC parameter with the first information element structure may provide (configure, define) the UE 102 to monitor PDCCH candidates for a first DCI format in the USS set. The UE 102 may, based on the received first RRC parameter, determine to monitor PDCCH candidates for the first DCI format in the USS set. The second RRC parameter with the second information element structure may provide (configure, define) the UE 102 to monitor PDCCH candidates for a second DCI format in the USS set. The UE 102 may, based on the received second RRC parameter, determine to monitor PDCCH candidates for the second DCI format in the USS set. The third RRC parameter with the first information element structure may provide (configure, define) the UE 102 to monitor PDCCH candidates for a third DCI format in a CSS set. Additionally or alternatively, the third RRC parameter with the first information element structure may provide the UE 102 to monitor PDCCH candidates for the third DCI format(s) in a USS set. The UE 102 may, based on the received third RRC parameter, determine to monitor PDCCH candidates for the third DCI format in a USS set or a CSS set. Here, the first DCI format may be the DCI format 0_1 and/or DCI format 1 1. The second DCI format may be the DCI format 0_2 and/or DCI format 1_2. The third DCI format may be the DCI format 0_0 and/or DCI format 1_0.

[0117] That, the first information element structure is capable of indicating that the search space is a CSS (CSS set) or a USS (USS set). The second information element structure is not capable of indicating that the search space is a common search space. The first DCI format, the second DCI format, and the third DCI format can be configured to be monitored in a USS set. The first DCI format and the second DCI format cannot be configured to be monitored in a CSS set. The third DCI format can be configured to be monitored in a CSS set.

[0118] In other words, the first RRC parameter with the first information element structure is capable of indicating that the search space set is a CSS (CSS set) or a USS (USS set). However, the first DCI format (e.g. DCI format 0_1 and DCI format 1_1) may be configured to be monitored in a USS set. The first DCI format (e.g. DCI format 0 1 and DCI format 1_1) may not be configured to be monitored in a CSS set.

[0119] The second RRC parameter with the second information element structure may provide the UE 102 that the search space set s is a USS set. Additionally or alternatively, the second RRC parameter with the second information element structure may not provide the UE 102 that the search space set s is a CSS set. The second RRC parameter with the second information element structure is not capable of indicating that the search space set is a CSS (CSS set). The second DCI format (e.g. DCI format 0_2 and DCI format 1_2) may be configured to be monitored in a USS set. The second DCI format (e.g. DCI format 0_2 and DCI format 1_2) may not be configured to be monitored in a CSS set.

[0120] The third RRC parameter with the first information element structure is capable of indicating that the search space set is a CSS (CSS set) or a USS (USS set). Therefore, the third DCI format (e.g. DCI format 0_0 and DCI format 1_0) may be configured to be monitored in a USS set. The third DCI format (e.g. DCI format 0_0 and DCI format 1_0) may be configured to be monitored in a CSS set. .

[0121] The UE 102 may perform 504 a procedure to determine PDCCH monitoring occasions in response to receiving the RRC parameters. At 504, the UE 102 may determine a first set of PDCCH monitoring occasions for a first set of PDCCH candidates based on the first RRC parameter with the first information element structure. At 504, the UE 102 may determine a second set of PDCCH monitoring occasions for a second set of PDCCH candidates based on the second RRC parameter with the second information element structure.

[0122] The UE 102 may perform 506 to monitor PDCCH candidates for corresponding search space set s. At 506, the UE 102 may monitor the first set of PDCCH candidates in the first set of PDCCH monitoring occasions for a corresponding search space set s, which is configured by the first RRC parameter. At 506, the UE 102 may monitor the second set of PDCCH candidates in the second set of PDCCH monitoring occasions for a corresponding search space set s, which is configured by the second RRC parameter.

[0123] Figure 6 is a flow diagram illustrating one implementation of a method 600 for search for PDCCH candidates by a base station 160.

[0124] The base station 160 may determine 602 RRC parameter(s). The base station 160 may generate 604 a RRC message including the RRC parameters. A RRC message may include system information. The 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. At 604, the base station 160 may generate a RRC message including a first RRC parameter(s) (e.g. SearchSpace ) with a first information element structure (e.g. information element structure A) for a UE 102. At 604, the base station 160 may generate a RRC message further including a second RRC parameter(s) (e.g. SearchSpace-v16) with a second information element structure (e.g. information element structure B or C) for a UE 102. At 604, the base station 160 may generate a RRC message including a third RRC parameter(s) (e.g. SearchSpace) with a first information element structure (e.g. information element structure A) for a UE 102. In other words, the first RRC parameter, the second RRC parameter and the third RRC parameter, which may be included in the RRC message, may be constructed by different information elements structure. The first RRC parameter, the second RRC parameter, and the third RRC parameter can be used to configure a search space set s, respectively. The first RRC parameter, the second RRC parameter and the third RRC parameter, which are related to search space set configuration, define the UE 102 how or where to search for PDCCH candidates. [0125] The base station 160 may configure the UE 102 to monitor PDCCH candidates for a first DCI format in a USS set via the first RRC parameter. Additionally or alternatively, the base station 160 may allocate the UE 102 to monitor PDCCH candidates for a second DCI format in a USS set via the second RRC parameter. The base station 160 may not allocate the UE 102 to monitor PDCCH candidates for a second DCI format in a CSS set via the second RRC parameter. The base station 160 may configure the UE 102 to monitor PDCCH candidates for a third DCI format in a CSS set or a USS set via the third RRC parameter. Here, the first DCI format may be the DCI format 0_1 and/or DCI format 1_1. The second DCI format may be the DCI format 0_2 and/or DCI format 1_2. The third DCI format may be the DCI format 0 0 and/or DCI format 1_0.

[0126] The base station 160 may broadcast system information including one or more RRC parameters related to search space configuration. Alternatively, or additionally, the base station 160 may 606 transmit, to a user equipment (UE), a radio resource control (RRC) message including one or more RRC parameters related to search space configuration. The base station 160 may transmit a first set of PDCCH candidates in a first set of PDCCH monitoring occasions according to the first RRC parameter. The base station 160 may transmit a second set of PDCCH candidates in a second set of PDCCH monitoring occasions according to the second RRC parameter. The base station 160 may transmit a third set of PDCCH candidates in a third set of PDCCH monitoring occasions according to the third RRC parameter. At 606, the base station 160 may transmit, to the UE 102, a RRC message including the first RRC parameter, which causes the UE 102 to monitor the first set of PDCCH candidates in the first set of PDCCH monitoring occasions for a corresponding search space set. At 606, the based station 160 may transmit, to the UE 102, a RRC message including the second RRC parameter, which causes the UE 102 to monitor the second set of PDCCH candidates in the second set of PDCCH monitoring occasions for a corresponding search space set. At 606, the based station 160 may transmit, to the UE 102, a RRC message including the third RRC parameter, which causes the UE 102 to monitor the third set of PDCCH candidates in the third set of PDCCH monitoring occasions for a corresponding search space set.

[0127] As mentioned in 502, a UE 102 may receive, from the base station 160, a RRC message including one or more RRC parameters related to search space configuration. The UE 102 may determine PDCCH monitoring occasions for PDCCH candidates for each search space set s based on the received the RRC parameters. The UE 102 may monitor PDCCH candidates for each search space set s in the determined PDCCH monitoring occasions. As above-mentioned, for example, a RRC parameter (e.g. SearchSpace or SearchSpace-v16) may provide the UE 102 for a search space set s, that a PDCCH monitoring periodicity of k _s slots, a PDCCH monitoring offset of o _s slots, a duration of T _s , a PDCCH monitoring pattern within a slot, and so on. Figure 7 is a diagram illustrating one example 700 how to determine PDCCH monitoring occasions for PDCCH candidates based on a received RRC parameter(s) related to search space configuration.

[0128] In Figure 7, the PDCCH monitoring periodicity k _s is configured as 6 slots. The PDCCH monitoring offset o _s is configured as 2 slots. The duration T _s is configured as 2 slots. The subcarrier spacing configuration u is configured as 0, which means the subcarrier spacing of the active DL BWP is 15kHz. In this case is equal to 10. That is, in a case u= 0, the number of slots per frame is 10. is the slot number within a radio frame. That is, the value of is in a range of {0, ..., }. [0129] The UE 102 may determine a PDCCH monitoring occasion on an active DL BWP from the PDCCH monitoring periodicity, the PDCCH monitoring offset, and the PDCCH monitoring pattern within a slot for each configured search space set s. For a search space set s, the UE 102, if the slot with number satisfies Formula ( 1 ) mod k _s = 0, may determine that a PDCCH monitoring occasion(s) exists in a slot with number in a frame with number According to Formula (1), the UE 102 may determine the slots with number in a frame with number np= 0 and the slot with number in a frame with number as the slots in which the PDCCH monitoring occasions exists. Given the T _s is configured as 2 slots, the UE 102 may monitors PDCCH candidates for search space set s for T _s =2 consecutive slots, staring from the determined the slots with number In other words, the UE 102 may not monitor PDCCH candidates for search space set s for the next (k _s - T _s ) consecutive slots. As depicted in Figure 7, the UE 102 may determine the slots with number =2, 3, 8, and 9 in a frame with number and the slots with number and 5 in a frame with number as the slots having PDCCH monitoring occasions. The UE 102 may monitor PDCCH candidates for search space set s in the determined slots configured for PDCCH monitoring. A slot having PDCCH monitoring occasions may also refer to a slot configured for PDCCH monitoring.

[0130] Furthermore, a slot determined (or configured) for PDCCH monitoring may have one or more than one PDCCH monitoring occasions. PDCCH monitoring pattern within the slot configured for PDCCH monitoring is indicated by a 14-bits string {monitor ingSymbolsWithinSloi). Each bit within the 14-bits string may correspond to a symbol within a slot, respectively. The most significant (left) bit (MSB) may represent the first OFDM in a slot, and the second most significant (left) bit may represent the second OFDM symbol in a slot and so on. The bit(s) set to one may identify the first OFDM symbol(s) of the control resource set within a slot. As depicted in Figure 7, a slot configured for PDCCH monitoring may have two PDCCH monitoring occasions. The first PDCCH monitoring occasion may be located on the first, second and third consecutive symbols. The second PDCCH monitoring occasion may be located on the 8 ^th , 9 ^th , and 10 ^th consecutive symbols. The duration of one PDCCH monitoring occasion may be the duration of a CORESET associated with the search space set s.

[0131] A UE may monitor a set of PDCCH candidates in the configured monitoring occasions in one or more configured control resource sets (CORESETs) according to the corresponding search space configurations.

[0132] DCI formats may be clarified as DCI format 0_0, DCI format 1_0, DCI format 1_1 (DCI format C), DCI format 0_1 (DCI format D), DCI format 1_2 (DCI format E), DCI format 0 2 (DCI format F), and so on.

[0133] DCI format 1_0 may be used for the scheduling of PDSCH in one cell. A UE may monitor the DCI format 1_0 with CRC scrambled by C-RNTI or CS-RNTI or MCS-C-RNTI or P-RNTI or SI-RNTI or RA-RNTI or TC-RNTI. The UE may monitor the DCI format 0_0 in a CSS (e.g. a CSS set) or a USS (e.g. a USS set). DCI format 0_0 may be used for the scheduling of PUSCH in one cell. A UE may monitor the DCI format 0_0 with CRC scrambled by C-RNTI or CS-RNTI or MCS-C-RNTI or TC- RNTI. The UE may monitor the DCI format 0_0 in a CSS (e.g. a CSS set) or a USS (e.g. a USS set).

[0134] Furthermore, the DCI format 1_0 monitored in a CSS may be used for the scheduling of broadcasting data. The DCI format 1_0 monitored in a CSS may be also used for the scheduling of UE-specific data. The DCI format 0_0 may be used for the scheduling of UE-specific data.

[0135] DCI format 0_0 may include predefined fields with fixed bits except for the ‘Frequency domain resource assignment’ field. The fields for DCI format 0_0 sequentially correspond to, ‘Identifier for DCI formats’ field with 1 bit, ‘Frequency domain resource assignment’ field, ‘Time domain resource assignment’ field with 4 bits, ‘Frequency hopping flag’ field with 1 bit, ‘Modulation and coding scheme’ field with 5 bits, ‘New data indicator’ field with 1 bit, ‘Redundancy version’ field with 2 bits, ‘HARQ process number’ field with 4 bits, ‘TPC command for scheduled PUSCH’ field with 2 bits, ‘UL/SUL indicator’ field with 1 bit. The size of the ‘Frequency domain resource assignment’ field for DCI format 0_0 may be determined based on a size of a UL bandwidth part. For example, the size of the ‘Frequency domain resource assignment’ field may be determined based on Formula (2) wherein the is a size of UL bandwidth part. The function ceil(x) means the function that takes as input a real number x and gives as output the least integer greater than or equal to x.

[0136] DCI format 1_0 may include predefined fields with fixed bits except for the ‘Frequency domain resource assignment’ field. The fields for DCI format 1_0 sequentially correspond to, ‘Identifier for DCI formats’ field with 1 bit, ‘Frequency domain resource assignment’ field, ‘Time domain resource assignment’ field with 4 bits, ‘VRB-to-PRB mapping’ field with 1 bit, ‘Modulation and coding scheme’ field with 5 bits, ‘New data indicator’ field with 1 bit, ‘Redundancy version’ field with 2 bits, ‘HARQ process number’ field with 4 bits, ‘Downlink assignment index’ field with 2 bits , ‘TPC command for scheduled PUCCH' field with 2 bits, ‘PUCCH resource indicator’ fie Id with 3 bits, ‘PDSCH-to-HARQ_feedback timing indicator’ field with 3 bits. The size of the ‘Frequency domain resource assignment’ fie Id for DCI format 1_0 may be determined based on a size of a DL bandwidth part, and/or a size of CORESET 0. For example, the size of the ‘Frequency domain resource assignment’ field may be determined based on Formula (3) wherein the is a size of UL bandwidth part or a size of CORESET 0.

[0137] DCI format 0_0 and DCI format l_0 can be configured to be monitored in a CSS (e.g. a CSS set) or a USS (e.g. a USS set). Hereinafter, a DCI format set A may include DCI format 0_0 and/or DCI format l _ 0, which are configured to be monitored in a CSS (e.g. a CSS set). The DCI format 0_0 and DCI format l_0 being monitored in a CSS may be also called as default DCI formats. A DCI format set B may include DCI format 0_0 and/or DCI format l_0, which are configured to be monitored in a USS (e.g. a USS set).

[0138] DCI format C may refer to DCI format (e.g. DCI format l_l) monitored in a USS. DCI format C (DCI format 1 1) may be used for the scheduling of PDSCH in one cell. DCI format 1_1 may schedule up to two transport blocks for one PDSCH. A UE may monitor the DCI format 1_1 with CRC scrambled by C-RNTI or CS-RNTI or MCS-C-RNTI. The UE may monitor the DCI format 1_1 in a USS The UE may not monitor the DCI format 1 1 in a CSS. DCI format 1_1 may be used for the scheduling of UE-specific data. DCI format 1_1 may include a plurality of fields with fixed bits and a plurality of fields with variable bits. The size of fields with variable bits are determined based on corresponding RRC configuration.

[0139] DCI format D may refer to DCI format (e.g. DCI format 0_1) monitored in a USS. DCI format 0_1 may be used for the scheduling of PUSCH in one cell. DCI format 0 1 may schedule up to two transport blocks for one PUSCH. A UE may monitor the DCI format 0_1 with CRC scrambled by C-RNTI or CS-RNTI or SP-CSI-RNTI or MCS-C-RNTI. The UE may monitor the DCI format 0_1 in a USS. The UE may not monitor the DCI format 0_1 in a CSS. DCI format 0 1 may be used for the scheduling of UE-specific data. DCI format 0_1 may include a plurality of fields with fixed bits and a plurality of fields with variable bits. The size of fields with variable bits are determined based on corresponding RRC configuration.

[0140] DCI format E may refer to DCI format (e.g. DCI format 1_2) monitored in a USS. DCI format 1_2 may be used for the scheduling of PDSCH in one cell. DCI format 1_2 may schedule one transport block for one PDSCH. A UE may monitor the DCI format 1_2 in a USS. The UE may not monitor the DCI format 1_2 in a CSS. DCI format 1_2 may be used for the scheduling of UE-specific data. 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.

[0141] DCI format F may refer to DCI format (e.g. DCI format 0_2) monitored in a USS. DCI format 0 2 may be used for the scheduling of PUSCH in one cell. DCI format 0_2 may schedule one transport block for one PUSCH. Additionally, UE may monitor the DCI format F with CRC scrambled by C-RNTI or CS-RNTI or SP-CSI- RNTI or MCS-C-RNTI. The UE may monitor the DCI format 0_2 in a USS. The UE may not monitor the DCI format 0_2 in a CSS. DCI format 0_2 may be used for the scheduling of UE-specific data. 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.

[0142] DCI formats C and D may be used to schedule traffic service data (e.g. eMBB). For example, DCI format C may be used to schedule a first PDSCH transmitting eMBB data. DCI format D may be used to schedule a first PUSCH transmitting eMBB data.

[0143] DCI formats E and F may be used to schedule traffic service data (e.g. URLLC). For example, DCI format E may be used to schedule a second PDSCH transmitting URLLC data. DCI format F may be used to schedule a second PUSCH transmitting URLLC data. Additionally or alternatively, DCI formats E and F may be DCI formats with CRC scrambled by a second RNTI which is different from a first RNTI(s) for DCI formats C and D. That is, DCI format E may be a DCI format 1_1 with CRC scrambled by a second RNTI. DCI format C may be a DCI format 1_1 with CRC scrambled by a first RNTI (e.g. C-RNTI). DCI format F may be a DCI format 0_1 with CRC scrambled by a second RNTI. DCI format D may be a DCI format 0_1 with CRC scrambled by a first RNTI (e.g. C-RNTI).

[0144] Additionally or alternatively, DCI formats C and D may be transmitted in a first CORESET, while DCI formats E and F may be transmitted in a second CORESET which is different from the first CORESET. A RRC parameter, which is used to identity the DCI formats configured by dci-Formats are DCI formats C and D or DCI formats E and F, may be present (or set to ‘enable’) in a CORESET configuration for the second CORESET. The RRC parameter may be absent (or set to ‘disable’) in a CORESET configuration for the first CORESET. As mentioned above, a CORESET is associated with a search space set s, in which DCI formats are configured to monitor. For example, dci-Formats may indicate to monitor PDCCH candidates for DCI format 0_1 and DCI format 1 1 in search space set s. If the RRC parameter is absent in the CORESET configuration for the associated CORESET, the DCI format 0 1 and DCI format 1_1 monitored in the CORESET may refer to DCI format C and D. If the RRC parameter is present in the CORESET configuration for the associated CORESET, the DCI format 0_1 and DCI format 1_1 monitored in the CORESET may refer to DCI format E and F. That is, the DCI format C and D may be the DCI format 0_1 and DCI format 1_1 monitored in the first CORESET. The DCI format C and D may be the DCI format 0_1 and DCI format 1_1 monitored in the second CORESET. [0145] Additionally or alternatively, DCI formats C and D may be transmitted in a first search space set s, while DCI formats E and F may be transmitted in a second search space set s which is different from the first search space set s. A RRC parameter, which is used to identity the DCI formats configured by dci-Formats are DCI formats C and D or DCI formats E and F, may be present (or set to ‘enable’) in ue-Specific SearchSpace , or SearchSpace-v16) for the second search space set s. The RRC parameter may be absent (or set to ‘disable’) in ue-Specific ( SearchSpace , or SearchSpace-v 16) for the first search space set s. For example, dci-Formats may indicate to monitor PDCCH candidates for DCI format 0_1 and DCI format 1_1 in search space set s. If the RRC parameter is absent in ue-Specific for the search space set s , the DCI format 0_1 and DCI format 1_1 monitored in the search space set s may refer to DCI format C and D. If the RRC parameter is present in ue-Specific for the search space set s , the DCI format 0_1 and DCI format 1_1 monitored in the search space set s may refer to DCI format E and F. That is, the DCI format C and D may be the DCI format 0_1 and DCI format 1 1 configured in the first search space set s. The DCI format C and D may be the DCI format 0 1 and DCI format 1_1 configured in the second search space set s.

[0146] DCI (format) used for the downlink scheduling is also referred to as downlink grant or downlink assignment. DCI (format) used for the uplink scheduling is also referred to as uplink grant or uplink assignment.

[0147] Different DCI formats may consist of different fields. The fields defined in the DCI formats maybe mapped to a number of information bits. Each field may be mapped to 0, 1, or more bits of the information bits. That is, a field may include 0, 1, or more bits of the information bits. In a case that a field is mapped to 0 bit, the UE may determine the field is absent in the DCI format. In other words, if a field is mapped to 1, or more bits, the UE may determine the field is present in the DCI format. Furthermore, a field may also include 0, 1, or more zero-padding bit(s). If the number of the information bits in DCI format is less than 12 bits, zero may be appended to the DCI format until the payload size equals 12. A DCI format may include a plurality of fields and 0, 1, or more zero-padding bit(s). The payload size of a DCI format may be equal to a quantity of the information bits and zero-padding bits(s). The number of the zero-padding bits may be 0, 1, or more bits for a DCI format. Herein, the size of a DCI format (DCI format size, DCI size) may refer to the payload size of the DCI format. Alternatively, or additionally, the size of a DCI format may also refer to the size of the information bits of the DCI format.

[0148] Different DCI formats may have different DCI format sizes. DCI formats having more different sizes, configured to a UE for a cell, would cause the burden of PDCCH blind decoding. To relax the processing of PDCCH blind decoding for a UE, the total number of different DCI format sizes may be restricted to a predefined number which the UE may monitor for a cell. That is, if the total number of different DCI format sizes exceed a predefined number, a base station and a UE may perform a DCI size alignment operation via padding or truncating some bits of some fields for a DCI format until the DCI format size equals to another DCI size. On the other hand, excessively restricting the number of the DCI format size which a UE may monitor for a cell, may affect the communication feature for a UE. For a DCI format, some fields, which may be introduced to implement communication features, would be truncated. Hence, it would be beneficial to dynamically configure a predefined number which a UE may monitor for a cell, according to the configured DCI formats for the UE. In other words, a base station and a UE may apply different conditions related to predefined numbers to determine whether to perform a DCI size alignment operation. The different conditions related to predefined numbers may be conditions A or conditions B.

[0149] Conditions A may be that, (i) the total number of different DCI sizes configured to monitor is no more than 4 for the cell, and (ii) the total number of different DCI sizes with C-RNTI configured to monitor is no more than 3 for the cell. If conditions A is fulfilled, the DCI size alignment procedure is complete.

[0150] Conditions B may be that, (iii) the total number of different DCI sizes configured to monitor is no more than X for the cell, and (iv) the total number of different DCI sizes with C-RNTI configured to monitor is no more than Y for the cell. In conditions B, the value of X and Y may be set to 5 and 4, respectively. In condition B, the value of X and Y may be set to 6 and 5, respectively. If conditions B is fulfilled, the DCI size alignment procedure is complete.

[0151] In conditions A and B, if a UE is provided by a new RNTI, (ii) of conditions

A is that, the total number of different DCI sizes with C-RNTI and the new RNTI configured to monitor is no more than 3 for the cell. Additionally, (iv) of conditions B is that, the total number of different DCI sizes with C-RNTI and the new RNTI configured to monitor is no more than Y for the cell.

[0152] Figure 8 is a flow diagram illustrating one implementation of a method 800 for DCI size alignment operation by a UE 102.

[0153] The UE 102 may receive 802, from the base station 160, a RRC message including one or more RRC parameter(s). At 802, the received one or more RRC pararaeter(s) (e.g. SearchSpace, SearchSpace-v16) may be related to one or more search space configuration(s). The UE 102 may be provided that which kinds of above- mentioned DCI formats may be monitored for a cell by the RRC parameters. In other words, the UE 102 may monitor one or more configured DCI formats based on the received RRC parameters from base station 160. Furthermore, at 802, the UE 102 may receive 802, from the base station 160, a RRC message including one or more RRC parameter(s) related to configuration(s) of DCI format(s). The one or more RRC parameter(s) related to configuration(s) of DCI format(s) may be used to determine the bitwidth of some fields for DCI format(s), for example, DCI format C, DCI format D, DCI format E, and/or DCI format F.

[0154] The UE 102 may perform 804 a procedure to respectively determine the size of the configured DCI formats and may potential perform DCI size alignment operation. In 804, the following one or more of steps from 804A to 804L may be performed sequentially or not sequentially.

[0155] (804A) the UE 102 may firstly determine the size of DCI formats in the

DCI format set A. In other words, the UE 102 may determine DCI format 0_0 monitored in a CSS. The UE 102 may determine the size of DCI format 0_0 monitored in a CSS, by calculating the Formula (2) in which is a size of the initial UL bandwidth part. The UE 102 may determine the size of DCI format 1_0 monitored in a CSS, by calculating the Formula (3) in which is given by the size of CORESET 0 if CORESET 0 is configured for the cell, or by the size of initial DL bandwidth part if CORESET 0 is not configured for the cell. If DCI format 0_0 is monitored in CSS and if the number of information bits in the DCI format 0_0 prior to padding is less than the payload size of the DCI format 1 0 monitored in CSS for scheduling the same cell, a number of zero-padding bits are generated for the DCI format 0_0 until the payload size equals that of the DCI format 1_0. If DCI format 0_0 is monitored in CSS and if the number of information bits in the DCI format 0_0 prior to truncation is larger than the payload size of the DCI format 1_0 monitored in CSS for scheduling the same cell, the bitwidth of the ‘frequency resource assignment’ field in the DCI format 0_0 is reduced by truncating the first few most significant bits such that the size of DCI format 0_0 equals to the size of the DCI format 1_0. The base station 160 and the UE 102 may align the size of DCI format 0_0 in CSS with that of DCI format 1_0 in CSS via the above procedures. In other words, the base station 160 and the UE 102 may determine the DCI formats within the DCI format set A as one same size. DCI formats within the DCI format set A may have one same size. Hereinafter, the (DCI) size of DCI format set A may refer to the size of DCI format 1 0 and/or DCI format 0 0, being monitored in a CSS.

[0156] (804B) After 804A, in 804B, the UE 102 may determine the size of DCI formats in the DCI format set B if the DCI formats are configured. In other words, the UE 102 may determine DCI format 0_0 monitored in a USS. The UE 102 may determine the size of DCI format 0_0 monitored in a USS, by calculating the Formula (2) in which is a size of the active UL bandwidth part. If the size of the active UL bandwidth part does not equal to the size of the initial UL bandwidth part, the size of DCI 0 0 monitored in a USS may be different from that of DCI 0_0 monitored in a CSS. The UE 102 may determine the size of DCI format 1_0 monitored in a USS, by calculating the Formula (3) in which is the size of active DL bandwidth part. Therefore, if CORESET 0 is configured for the cell and if size of the active DL bandwidth part does not equal to the size of the CORESET 0, the size of DCI 1_0 monitored in a USS may be different from that of DCI 1 0 monitored in a CSS. If CORESET 0 is not configured for the cell and if the size of active DL bandwidth part does not equal to the size of the initial DL bandwidth part, the size of DCI 1_0 monitored in a USS may be different from that of DCI 1_0 monitored in a CSS.

[0157] (804C) After 804B, in 804C, if DCI format 0 0 is monitored in USS and if the number of information bits in the DCI format 0_0 prior to padding is less than the payload size of the DCI format 1_0 monitored in USS for scheduling the same cell, a number of zero-padding bits are generated for the DCI format 0_0 until the payload size equals that of the DCI format 1_0. If DCI format 1_0 is monitored in USS and if the number of information bits in the DCI format 1_0 prior to padding is less than the payload size of the DCI format 0_0 monitored in USS for scheduling the same cell, a number of zero-padding bits may be generated and appended to the DCI format 1 0 until the payload size equals that of the DCI format 0_0. The base station 160 and the UE 102 may align the size between DCI format 0 0 in USS and DCI format 1_0 in USS via the above procedures. In other words, the base station 160 and the UE 102 may determine the DCI formats with the DCI format set B as one same size. DCI formats within the DCI format set B may have one same size. Hereinafter, the (DCI) size of DCI format set B may refer to the size of DCI format 1_0 and/or DCI format 0 0, being monitored in a USS. The size of DCI format set B may be different from the size of the DCI format set A. The size of DCI format set B may be same with the size of the DCI format set A.

[0158] (804D) In 804D, the UE 102 may determine the size of DCI format C if the DCI format C is configured. In other words, the UE 102 may determine DCI format 1_1 monitored in a USS. The UE 102 may determine the size of DCI format 1 1 monitored in a USS, based on the received RRC parameters.

[0159] (804E) After 804D, in 804E, if the size of DCI format 1_1 equals that of a

DCI format set B, the base station 160 and/or the UE 102 may append one bit of zeropadding to the DCI format 1_1. Therefore, the size of DCI format C may be different from the size of the DCI format set B. Therefore, the size of DCI format C may not be same with the size of the DCI format set B.

[0160] (804F) After 804E, in 804F, the UE 102 may determine the size of DCI format D if the DCI format D is configured. In other words, the UE 102 may determine DCI format 0 1 monitored in a USS. The UE 102 may determine the size of DCI format 0 1 monitored in a USS, based on the received RRC parameters.

[0161] (804G) After 804F, in 804G, if the size of DCI format 0_1 equals that of the DCI format set B, the base station 160 and/or the UE 102 may append one bit of zero-padding to the DCI format 0_1. Therefore, the size of DCI format D may be different from the size of the DCI format set B. Therefore, the size of DCI format D may not be same with the size of the DCI format set B.

[0162] (804H) After 804G, in 804H, the UE 102 may determine the size of DCI format E if the DCI format E is configured. In other words, the UE 102 may determine DCI format 1_2 monitored in a USS. The UE 102 may determine the size of DCI format 1_2 monitored in a USS, based on the received RRC parameters.

[0163] (8041) After 804H, in 8041,, the UE 102 may determine the size of DCI format F if the DCI format F is configured. In other words, the UE 102 may determine DCI format 0_2 monitored in a USS. The UE 102 may determine the size of DCI format 0_2 monitored in a USS, based on the received RRC parameters.

[0164] (804J) In 804 J, the UE 102 and the base station 160 may or may not perform a DCI size alignment procedure for DCI format E and DCI format F. In 804J, the UE 102 and the base station 160 may perform a DCI size alignment procedure for DCI format E and DCI format F. In other words, if the number of information bits in the DCI format 0_2 does not equal that in the DCI format 1 2, the UE 102 and the base station 160 may append zero-padding bit(s) to a DCI format with less size such that the size of DCI format 0 2 monitored in a USS equals the size of the DCI format 1_2 monitored in a USS. In this case, the size of DCI format E may be same with the size of DCI format F. Alternatively, the UE 102 and the base station 160 may not perform a DCI size alignment procedure for DCI format E and DCI format F. In this case, the size of DCI format E may be or may not be same with the size of DCI format F. For example, if the UE 102 is not configured to monitor DCI format C and D, the UE 102 and the base station 160 may not perform a DCI size alignment procedure for the DCI format E and DCI format F. In 804 J, if UE 102 and the base station 160 perform a DCI size alignment procedure for DCI format E and DCI format F, DCI format E and DCI format F have a same size. In this case, the size of DCI format E hereinafter may also refer to the size of DCI format F.

[0165] (804K) After 804J, in 804K, if the size of DCI format 1_2 equals that of a

DCI format in a fourth DCI format group, the base station 160 and/or the UE 102 may append one bit of zero-padding to the DCI format in the fourth DCI format group. Therefore, the size of DCI format 1 2 may be different from the size of the DCI format in the fourth DCI format group. Therefore, the size of DCI format 1_2 may not be same with the size of DCI format in the fourth DCI format group. Here, the fourth DCI format group may contain the DCI formats within the DCI format set B, DCI format C, and DCI format D. The fourth DCI format group may not contain the DCI formats within the DCI format set A. The fourth DCI format group may not contain the DCI format F. Zero-padding may increase the payload size of the DCI format, which may increase the possibility of decoding error for the DCI format. Thereby, via appending the zeropadding bits to the DCI format in the fourth DCI format group but not to the DCI format 1_2, the transmission reliability of the DCI format 1_2 may not deteriorate.

[0166] (804L) If the size of DCI format 0_2 equals that of a DCI format in a fourth

DCI format group, the base station 160 and/or the UE 102 may append one bit of zeropadding to the DCI format in the fourth DCI format group. Therefore, the size of DCI format 0_2 may be different from the size of DCI format in the fourth DCI format group. Therefore, the size of DCI format 0_2 may not be same with the size of DCI format in the fourth DCI format group. Here, the fourth DCI format group may contain the DCI formats within the DCI format set B, DCI format C, and DCI format D. The fourth DCI format group may not contain the DCI formats within the DCI format set A. The fourth DCI format group may not contain the DCI format F.

[0167] Furthermore, after implementing either (804K) or (804L), the DCI format in the fourth DCI format group after being appended the zero-padding bits may have same DCI size with another DCI format in the fourth DCI format group. In this case, the UE 102 and the base station 160 may further implement the (804E) and (804G) until the DCI formats within the fourth DCI format group do not have a same size with each other.

[0168] As described above, the UE 102 and the base station 160 may sequentially perform (804E) and/or (804G), then perform (804K) and/or (804L), and then perform (804E) and/or (804G). Alternatively, the UE 102 and the base station 160 may firstly perform (804K) and/or (804L). Then the UE 102 and the base station 160 may further perform (804K) and/or (804L), if necessary.

[0169] The UE 102 may 806 determine which a first condition(s) or a second condition(s) is used based on the configured DCI format(s) which the UE 102 may monitor for a cell. The first condition(s) may refer to the above-mentioned conditions A. The second conditions(s) may refer to the above-mentioned conditions B. The first condition(s) and/or the second condition(s) may be used to determine whether the DCI size alignment procedure is complete. The UE 102 may determine whether a DCI size alignment procedure is complete based on the first condition(s). The UE 102 may determine whether a DCI size alignment procedure is complete based on the second condition(s).

[0170] In a first case that either a first DCI format set or a second DCI format set is configured to monitor, the UE 102 may determine to use the first condition(s) to determine whether a DCI size alignment procedure is complete. In a second case that both the first DCI format set and the second DCI format set are configured to monitor, the UE 102 may determine to use the second condition(s) to determine whether a DCI size alignment procedure is complete. The first DCI format set may contain DCI format C and/or DCI format D. The second DCI format set may contain DCI format E and/or DCI format F.

[0171] Additionally or alternatively, in a third case that a first DCI format set is configured to monitor and the second DCI format set is not configured to monitor, the UE 102 may determine to use the first condition(s) to determine whether a DCI size alignment procedure is complete. In a fourth case that the second DCI format set is configured to monitor and the first DCI format set is not configured to monitor, the UE 102 may determine to use the second condition(s) to determine whether a DCI size alignment procedure is complete. That is, as long as the second DCI format set is configured to monitor, the UE 102 may determine to use the second condition(s) to determine whether a DCI size alignment procedure is complete.

[0172] Additionally or alternatively, at 802, UE 102 may receive, from base station 160, a RRC message further including a RRC parameter, which is used to indicate UE 102 to monitor DCI formats based on the first case or the second case. If the RRC parameter configure UE 102 to monitor DCI formats based on the first case, the UE 102 may determine to use the first condition(s) to determine whether a DCI size alignment procedure is complete. If the RRC parameter configure UE 102 to monitor DCI formats based on the second case, the UE 102 may determine to use the second condition(s) to determine whether a DCI size alignment procedure is complete.

[0173] Additionally or alternatively, whether to use the first conditions(s) or the second condition(s) maybe indicated by a RRC parameter. At 802, UE 102 may receive, from base station 160, a RRC message further including a RRC parameter, which is used to indicate UE 102 to use the first condition(s) or the second condition(s) to determine whether a DCI size alignment procedure is complete. In a case that the RRC parameter configure UE 102 to use the first condition(s), the UE 102 may determine to use the first condition(s) to determine whether a DCI size alignment procedure is complete. In a case that the RRC parameter configure UE 102 to use the second condition(s), the UE 102 may determine to use the second condition(s) to determine whether a DCI size alignment procedure is complete.

[0174] Additionally or alternatively, at 802, UE 102 may receive, from base station 160, a RRC message further including a RRC parameter (e.g searchSpaceType and/or searchSpaceType-v16). If a RRC parameter searchSpaceType-v16 is configured for the UE 102, the UE 102 may determine to use the second condition(s) to determine whether a DCI size alignment procedure is complete. If RRC parameter searchSpaceType-v16 is not configured for the UE 102, the UE 102 may determine to use the first condition(s) to determine whether a DCI size alignment procedure is complete. In other words, if RRC parameter(s) searchSpaceType is configured and if a RRC parameter searchSpaceType-v16 is not configured for the UE 102, the UE 102 may determine to use the first condition(s) to determine whether a DCI size alignment procedure is complete.

[0175] The UE 102 may 808 judge that the condition(s) determined in 806 are fulfilled or not. If determined condition(s) are fulfilled, the UE 102 may determine that 812 the DCI size alignment procedure is complete. If determined condition(s) are not fulfilled, the UE 102 may determine that the DCI size alignment procedure has not been completed. In this case, the UE 102 may 810 further perform potential DCI size alignment operation. That is, the UE 102 may adjust a size of a DCI format by padding or truncation to make sure the size of the DCI format equals to that of another DCI format. The UE 102 may generate or append a number of zero-padding bits to a DCI format with smaller size such that the size of the DCI format equals to that of another DCI format. Additionally or alternatively, the UE 102 may truncate some bits of some fields for a DCI format with larger size such that the size of the DCI format equals to that of another DCI format.

[0176] For example, at 810, the UE 102 may remove the padding bit (if any) introduced in 804 above. The UE 102 may determine the size of DCI format 1_0 monitored in a USS, by calculating the Formula (3) in which is given by the size of CORESET 0 if CORESET 0 is configured for the cell, or by the size of initial DL bandwidth part if CORESET 0 is not configured for the cell. The UE 102 may determine the size of DCI format 0_0 monitored in a USS, by calculating the Formula (2) in which is a size of the initial UL bandwidth part. If the number of information bits in the DCI format 0_0 monitored in USS prior to padding is less than the payload size of the DCI format 1_0 monitored in USS for scheduling the same cell, a number of zero-padding bits are generated for the DCI format 0_0 monitored in a USS until the payload size equals that of the DCI format 1_0 monitored in a USS. If the number of information bits in the DCI format 0_0 monitored in USS prior to truncation is larger than the payload size of the DCI format 1_0 monitored in USS for scheduling the same cell, the bitwidth of the ‘frequency domain resource assignment’ field in the DCI format 0_0 is reduced by truncating the first few most significant bits such that the size of DCI format 0_0 monitored in a USS equals the size of the DCI format 1_0 monitored in a USS. Here, the base station 160 and the UE 102 may further perform the above DCI size alignment procedure to align the size between DCI formats within the DCI format set A and DCI formats within the DCI format set B. In this case, the size of the DCI format set B may be same with the size of the DCI format set A. [0177] Figure 9 is a flow diagram illustrating one implementation of a method 900 for DCI size alignment operation by a base station 160.

[0178] As mentioned in method 600, the base station 160 may allocate a UE 102 to monitor which kinds of DCI formats via determining one or more RRC parameter(s) related to search space configuration. As above-mentioned, the search space configuration(s) may involve the configuration(s) of DCI format(s). The base station 160 may generate a RRC message including the one or more RRC parameter(s) and transmit the RRC message to the UE 102. That is, the base station 160 may allocated the UE 102 to monitor one or more configured DCI formats according to transmit the one or more RRC parameters to the UE 102.

[0179] The base station 160 may transmit the configured DCI format(s) with a respective size. The based station 160 may determine each size of the configured DCI format(s) according to the method 900 and transmit the configured DCI format(s) with the determined size to the UE 102. The UE 102 may monitor the configured DCI format(s) with the determined size for respective corresponding search space set s. [0180] The based station 160 may 902 perform a procedure to respectively determine the size of the configured DCI formats and may potential perform DCI size alignment operation. Given the procedure of 902 is similar with that of 804, the description of 902 is omitted.

[0181] The based station 160 may 904 determine to use a first condition(s) or a second condition(s) bases on the configured DCI format which the UE 102 may monitor for a cell. The first condition(s) may refer to the above-mentioned conditions A. The second conditions(s) may refer to the above-mentioned conditions B. The first condition(s) and/or the second condition(s) may be used to determine whether the DCI size alignment procedure is complete. The base station 160 may determine whether a DCI size alignment procedure is complete based on the first condition(s). The base station 160 may determine whether a DCI size alignment procedure is complete based on the second condition(s).

[0182] In a case that the base station 160 configures the UE 102 to monitor one of either a first DCI format set or a second DCI format set, the base station 160 may determine to use the first condition(s) to determine whether a DCI size alignment procedure is complete. In a case that the base station 160 configures the UE 102 to monitor both the first DCI format set or the second DCI format set, the base station 160 may determine to use the second condition(s) to determine whether a DCI size alignment procedure is complete. The first DCI format set may contain DCI format C and/or DCI format D. The second DCI format set may contain DCI format E and/or DCI format F.

[0183] Additionally or alternatively, a base station 160 may transmit, to a UE 102, a RRC message further including a RRC parameter, which is used to indicate UE 102 to monitor DCI formats based on the first case or the second case. If the RRC parameter configure UE 102 to monitor DCI formats based on the first case, the UE 102 may determine to use the first condition(s) to determine whether a DCI size alignment procedure is complete. If the RRC parameter configure UE 102 to monitor DCI formats based on the second case, the UE 102 may determine to use the second condition(s) to determine whether a DCI size alignment procedure is complete.

[0184] Additionally or alternatively, whether to use the first conditions(s) or the second condition(s) maybe indicated by a RRC parameter. A base station 160 may transmit, to a UE 102, a RRC message further including a RRC parameter, which is used to indicate UE 102 to use the first condition(s) or the second condition(s) to determine whether a DCI size alignment procedure is complete. In a case that the RRC parameter configure UE 102 to use the first condition(s), the UE 102 may determine to use the first condition(s) to determine whether a DCI size alignment procedure is complete. In a case that the RRC parameter configure UE 102 to use the second condition(s), the UE 102 may determine to use the second condition(s) to determine whether a DCI size alignment procedure is complete.

[0185] The base station 160 may 906 judge that the condition(s) determined in 904 are fulfilled or not. If determined condition(s) are fulfilled, the base station 160 may determine that 910 the DCI size alignment procedure is complete. If determined condition(s) are not fulfilled, the base station 160 may determine that the DCI size alignment procedure has not been completed. In this case, the base station 160 may 908 further perform potential DCI size alignment operation. That is, the base station 160 may adjust a size of a DCI format by padding or truncation to make sure the size of the DCI format equals to that of another DCI format. The base station 160 may generate or append a number of zero-padding bits to a DCI format with smaller size such that the size of the DCI format equals to that of another DCI format. Additionally or alternatively, the base station 160 may truncate some bits of some fields for a DCI format with larger size such that the size of the DCI format equals to that of another DCI format.

[0186] According to the above procedures 800 and 900, the base station 160 may respectively determine the size of configured DCI format(s) which would be monitored by the UE 102. The base station 160 may 912 transmit, to the UE 102, the configured DCI format(s) with determined size(s) on corresponding PDCCH monitoring occasions for respective corresponding search space set s. The UE 102 may monitor the configured DCI format(s) with the determined size(s) on corresponding PDCCH monitoring occasions for respective corresponding search space set s.

[0187] According to another implementation of 800 and 900, the UE 102 may be configured to use the conditions A to determine whether a DCI size alignment procedure is complete or not. That is, at 806 and 904, the UE 102 and/or the base station 160 may determine to use a first condition(s) regardless what kind of DCI formats are configured to monitor for the UE 102. Given the first conditions are used, the UE 102 and the base station 160 may align the size of DCI format E and/or DCI format F with the size of other DCI formats to reduce the total number of different DCI format -sizes. The implementation hereinafter may not be applied to the UE 102 who is not configured to monitor DCI format C and D. That is, if the UE 102 is not configured to monitor the DCI format C and D, the UE 102 may not perform the implementation. In this implementation, the UE 102 and the base station 160 may perform the above-mentioned steps until step 804J. After accomplishing the above-mentioned 804J, the UE 102 and the base station 160 next may perform some different DCI size alignment steps in 804. The UE 102 and the base station 160 may compare the size of DCI format E (or DCI format F) with the size of other configured DCI formats, and if theirs sizes are different, perform the DCI alignment operation for these DCI formats having different sizes. In other words, if theirs sizes are different, the UE 102 and the base station 160 may select a DCI format and may adjust the size of the selected DCI format by padding or truncation in order to fulfill the first conditions.

[0188] For example, in a case that the payload size of DCI format E (or DCI format F) is less than the payload size of a DCI format in a fifth DCI format group, the UE 102 and the base station 160 may generate (append) a number of zero-padding bits for the DCI format E (or DCI format F) until the payload size equals that of the DCI format in the fifth DCI format group. The fifth DCI format group may contain the DCI formats within the DCI format set A. The fifth DCI format group may not contain other DCI formats like the DCI formats within the DCI format set B, DCI format C, or DCI format D. Alternatively, the fifth DCI format group may contain all the configured DCI formats other than DCI format E and F.

[0189] For example, in a case that the payload size of DCI format E (or DCI format F) is larger than that of any DCI formats configured to the UE 102, the UE 102 and the base station 160 may select a DCI format from the configured DCI formats other than the DCI formats in the DCI format set A, wherein the select DCI format have a payload size being less than but closest to that of DCI format E (or DCI format F). In other words, in this case, UE 102 and the base station 160 may select a DCI format with a largest size from a set of DCI formats whose sizes are less than that of DCI format E (or DCI format F). The set of DCI formats does not contain the DCI formats in the DCI format set A. Then the UE 102 and the base station 160 may generate (append) a number of zero-padding bits for the selected DCI format until the payload size equals that of the DCI format E (or DCI format F).

[0190] The UE 102 and the base station 160 may compare the size of DCI format E (or DCI format F) with a DCI format within a sixth DCI format group. The sixth DCI format group may contain the DCI format C, and/or the DCI format D. The sixth DCI format group may not contain the DCI formats within the DCI format set A, and/or the DCI formats within the DCI format set B.

[0191] For example, in a case that there are no DCI format(s) in the sixth DCI format group whose payload sizes are larger than the payload size of DCI format E (or DCI format F), the UE 102 and base station 160 may select a DCI format from the sixth DCI format group, wherein the select DCI format have a payload size being less than but closest to that of DCI format E (or DCI format F). In other words, in this case, UE 102 and the base station 160 may select a DCI format with a largest size from a set of DCI formats in the sixth DCI format group. The set of DCI formats are those DCI formats whose sizes are less than that of DCI format E (or DCI format F). Then the UE 102 and the base station 160 may generate (append) a number of zero-padding bits for the selected DCI format until the payload size equals that of the DCI format E (or DCI format F). [0192] For example, in a case that there are no DCI format(s) in the sixth DCI format group whose payload size are less than the payload size of DCI format E (or DCI format F), the UE 102 and base station 160 may select a DCI format from the sixth DCI format group, wherein the select DCI format have a payload size being larger than but closest to that of DCI format E (or DCI format F). In other words, in this case, UE 102 and the base station 160 may select a DCI format with a smallest size from a set of DCI formats in the sixth DCI format group. The set of DCI formats are those DCI formats whose sizes are larger than that of DCI format E (or DCI format F). Then the UE 102 and the base station 160 may generate (append) a number of zero-padding bits for the DCI format E (or DCI format F) until the payload size equals that of he selected DCI format. Here, the payload size of DCI format E (or DCI format F) may be larger than that of the DCI format set A.

[0193] For example, in a case that there are one or more first DCI format(s) in the sixth DCI format group whose payload size are less than that of DCI format E (or DCI format F) and there also are one or more second DCI format(s) in the sixth DCI format group whose payload size are larger than that of DCI format E (or DCI format F), the UE 102 and base station 160 may select a DCI format from the one or more first DCI format(s), wherein the selected DCI format have a payload size being less than but most near to that of DCI format E (or DCI format F). Then the UE 102 and the base station 160 may generate (append) a number of zero-padding bits for the selected DCI format until the payload size equals that of the DCI format E (or DCI format F). Additionally or alternatively, in this case, the UE 102 and base station 160 may select a DCI format from the one or more second DCI format(s), wherein the selected DCI format have a payload size being larger than but most near to that of DCI format E (or DCI format F). Then the UE 102 and the base station 160 may generate (append) a number of zeropadding bits for the DCI format E (or DCI format F) until the payload size equals that of he selected DCI format.

[0194] In the implementation, the UE 102 and the base station 160 may align the size of one configured DCI format with the size of another configured DCI formats via padding or truncating the size of the one configured DCI format. The total number of DCI format sizes would be adjusted to fulfill the first conditions. As illustrated in above examples, the UE 102 and the base station 160 may not align the size of DCI format set B with the size of DCI format E (or DCI format F). On the contrary, the UE 102 and the base station 160 may not align the size of DCI format E (or DCI format F) with the size of DCI format set B. The UE 102 and the base station 160 may align the size of DCI format C (or DCI format D) with the size of DCI format E (or DCI format F). The UE 102 and the base station 160 may align the size of DCI format E (or DCI format F) with the size of DCI format C, or DCI format D. The UE 102 and the base station 160 may not align the size of DCI format set A with the size of DCI format E (or DCI format F). The UE 102 and the base station 160 may align the size of DCI format E (or DCI format F) with the size of DCI format set A.

[0195] Figure 10 illustrates various components that may be utilized in a UE 1002.

The UE 1002 described in connection with Figure 10 may be implemented in accordance with the UE 102 described in connection with Figure 1. The UE 1002 includes a processor 1081 that controls operation of the UE 1002. The processor 1081 may also be referred to as a central processing unit (CPU). Memory 1087, 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 1083a and data 1085a to the processor 1081. A portion of the memory 1087 may also include non-volatile random access memory (NVRAM). Instructions 1083b and data 1085b may also reside in the processor 1081. Instructions 1083b and/or data 1085b loaded into the processor 1081 may also include instructions 1083a and/or data 1085a from memory 1087 that were loaded for execution or processing by the processor 1081. The instructions 1083b may be executed by the processor 1081 to implement one or more of the methods 200 described above.

[0196] The UE 1002 may also include a housing that contains one or more transmitters 1058 and one or more receivers 1020 to allow transmission and reception of data. The transmitter(s) 1058 and receiver(s) 1020 may be combined into one or more transceivers 1018. One or more antennas 1022a-n are attached to the housing and electrically coupled to the transceiver 1018.

[0197] The various components of the UE 1002 are coupled together by a bus system 1089, 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 10 as the bus system 1089. The UE 1002 may also include a digital signal processor (DSP) 1091 for use in processing signals. The UE 1002 may also include a communications interface 1093 that provides user access to the functions of the UE 1002. The UE 1002 illustrated in Figure 10 is a functional block diagram rather than a listing of specific components.

[0198] Figure 11 illustrates various components that may be utilized in a base station 1160. The base station 1160 described in connection with Figure 11 may be implemented in accordance with the base station 160 described in connection with Figure 1. The base station 1160 includes a processor 1181 that controls operation of the base station 1160. The processor 1181 may also be referred to as a central processing unit (CPU). Memory 1187, 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 1183a and data 1185a to the processor 1181. A portion of the memory 1187 may also include non-volatile random access memory (NVRAM). Instructions 1183b and data 1185b may also reside in the processor 1181. Instructions 1183b and/or data 1185b loaded into the processor 1181 may also include instructions 1183a and/or data 1185a from memory 1187 that were loaded for execution or processing by the processor 1181. The instructions 1183b may be executed by the processor 1181 to implement one or more of the methods 300 described above.

[0199] The base station 1160 may also include a housing that contains one or more transmitters 1117 and one or more receivers 1178 to allow transmission and reception of data. The transmitter(s) 1117 and receiver(s) 1178 may be combined into one or more transceivers 1176. One or more antennas 1180a— n are attached to the housing and electrically coupled to the transceiver 1176.

[0200] The various components of the base station 1160 are coupled together by a bus system 1189, 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 11 as the bus system 1189. The base station 1160 may also include a digital signal processor (DSP) 1191 for use in processing signals. The base station 1160 may also include a communications interface 1193 that provides user access to the functions of the base station 1160. The base station 1160 illustrated in Figure 11 is a functional block diagram rather than a listing of specific components. [0201] 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.

[0202] 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.

[0203] 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.

[0204] 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.