PRIORITY CLAIM

[0001] This application claims the benefit of priority to United States Provisional Patent Application Serial No. 63/141,674, filed January 26, 2021, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] Embodiments pertain to next generation (NG) wireless communications. In particular, some embodiments relate to cell search and selection in NG networks.

BACKGROUND

[0003] The use and complexity of new radio (NR) wireless systems, which include 5 ^th generation (5G) networks and are starting to include sixth generation (6G) networks among others, has increased due to both an increase in the types of devices UEs using network resources as well as the amount of data and bandwidth being used by various applications, such as video streaming, operating on these UEs. With the vast increase in number and diversity of communication devices, the corresponding network environment, including routers, switches, bridges, gateways, firewalls, and load balancers, has become increasingly complicated. As expected, a number of issues abound with the advent of any new technology.

BRIEF DESCRIPTION OF THE FIGURES

[0004] In the figures, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The figures illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

[0005] FIG. 1 A illustrates an architecture of a network, in accordance with some aspects. [0006] FIG. 1B illustrates a non-roaming 5G system architecture in accordance with some aspects.

[0007] FIG. 1 C illustrates a non-roaming 5G system architecture in accordance with some aspects.

[0008] FIG. 2 illustrates a block diagram of a communication device in accordance with some embodiments.

[0009] FIG. 3 illustrates 5G NR control plane (CP) state transitions in accordance with some aspects.

[0010] FIG. 4A illustrates 5G NR radio resource control (RRC) state transitions in accordance with some aspects.

[0011] FIG. 4B illustrates 5G NR RRC states of the RRC state transitions in FIG. 4A in accordance with some aspects.

[0012] FIG. 5 illustrates RRCJDLE and RRCJNACTIVE Cell Selection and Reselection in accordance with some aspects.

[0013] FIG. 6 illustrates public/private network scenarios in accordance with some aspects.

[0014] FIG. 7 illustrates radio link failure (RLF) actions in accordance with some aspects.

[0015] FIG. 8 illustrates a 5GNR initial access procedure in accordance with some aspects.

_{DETAILED DESCRIPTION}

[0016] The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims.

[0017] FIG. 1 A illustrates an architecture of a network in accordance with some aspects. The network 140A includes 3GPP LTE/4G and NG network functions that may be extended to 6G functions. Accordingly, although 5G will be referred to, it is to be understood that this is to extend as able to 6G structures, systems, and functions. A network function can be implemented as a discrete network element on a dedicated hardware, as a software instance running on dedicated hardware, and/or as a virtualized function instantiated on an appropriate platform, e.g., dedicated hardware or a cloud infrastructure.

[0018] The network 140A is shown to include user equipment (UE) 101 and UE 102. The UEs 101 and 102 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks) but may also include any mobile or non-mobile computing device, such as portable (laptop) or desktop computers, wireless handsets, drones, or any other computing device including a wired and/or wireless communications interface. The UEs 101 and 102 can be collectively referred to herein as UE 101, and UE 101 can be used to perform one or more of the techniques disclosed herein.

[0019] Any of the radio links described herein (e.g., as used in the network 140 A or any other illustrated network) may operate according to any exemplary radio communication technology and/or standard. Any spectrum management scheme including, for example, dedicated licensed spectrum, unlicensed spectrum, (licensed) shared spectrum (such as Licensed Shared Access (LSA) in 2.3-2.4 GHz, 3.4-3.6 GHz, 3.6-3.8 GHz, and other frequencies and Spectrum Access System (SAS) in 3.55-3.7 GHz and other frequencies). Different Single Carrier or Orthogonal Frequency Domain Multiplexing (OFDM) modes (CP-OFDM, SC-FDMA, SC-OFDM, filter bank-based multicarrier (FBMC), OFDMA, etc.), and in particular 3GPP NR, may be used by allocating the OFDM carrier data bit vectors to the corresponding symbol resources.

[0020] In some aspects, any of the UEs 101 and 102 can comprise an Intemet-of-Things (loT) UE or a Cellular loT (CIoT) UE, which can comprise a network access layer designed for low-power loT applications utilizing short- lived UE connections. In some aspects, any of the UEs 101 and 102 can include a narrowband (NB) loT UE (e.g., such as an enhanced NB-IoT (eNB-IoT) UE and Further Enhanced (FeNB-IoT) UE). An loT UE can utilize technologies such as machine-to-machine (M2M) or machine-type communications (MTC) for exchanging data with an MTC server or device via a public land mobile network (PLMN), Proximity-Based Service (ProSe) or device-to-device (D2D) communication, sensor networks, or loT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An loT network includes interconnecting loT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The loT UEs may execute background applications (e.g., keep- alive messages, status updates, etc.) to facilitate the connections of the loT network. In some aspects, any of the UEs 101 and 102 can include enhanced MTC (eMTC) UEs or further enhanced MTC (FeMTC) UEs.

[0021] The UEs 101 and 102 may be configured to connect, e.g., communicatively couple, with a radio access network (RAN) 110. The RAN 110 may be, for example, an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), a NextGen RAN (NG RAN), or some other type of RAN.

[0022] The UEs 101 and 102 utilize connections 103 and 104, respectively, each of which comprises a physical communications interface or layer (discussed in further detail below); in this example, the connections 103 and 104 are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a code-division multiple access (CDMA) network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3GPP Long Term Evolution (LTE) protocol, a 5G protocol, a 6G protocol, and the like.

[0023] In an aspect, the UEs 101 and 102 may further directly exchange communication data via a ProSe interface 105. The ProSe interface 105 may alternatively be referred to as a sidelink (SL) interface comprising one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery Channel (PSDCH), a Physical Sidelink Broadcast Channel (PSBCH), and a Physical Sidelink Feedback Channel (PSFCH).

[0024] The UE 102 is shown to be configured to access an access point (AP) 106 via connection 107. The connection 107 can comprise a local wireless connection, such as, for example, a connection consistent with any IEEE 802.11 protocol, according to which the AP 106 can comprise a wireless fidelity (WiFi®) router. In this example, the AP 106 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below).

[0025] The RAN 110 can include one or more access nodes that enable the connections 103 and 104. These access nodes (ANs) can be referred to as base stations (BSs), NodeBs, evolved NodeBs (eNBs), Next Generation NodeBs (gNBs), RAN nodes, and the like, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). In some aspects, the communication nodes 111 and 112 can be transmission/reception points (TRPs). In instances when the communication nodes 111 and 112 are NodeBs (e.g., eNBs or gNBs), one or more TRPs can function within the communication cell of the NodeBs. The

RAN 110 may include one or more RAN nodes for providing macrocells, e.g., macro RAN node 111, and one or more RAN nodes for providing femtocells or picocells (e.g., cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells), e.g., low power (LP) RAN node 112. [0026] Any of the RAN nodes 111 and 112 can terminate the air interface protocol and can be the first point of contact for the UEs 101 and 102. In some aspects, any of the RAN nodes 111 and 112 can fulfill various logical functions for the RAN 110 including, but not limited to, radio network controller (RNC) functions such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management. In an example, any of the nodes 111 and/or 112 can be a gNB, an eNB, or another type of RAN node.

[0027] The RAN 110 is shown to be communicatively coupled to a core network (CN) 120 via an SI interface 113. In aspects, the CN 120 may be an evolved packet core (EPC) network, a NextGen Packet Core (NPC) network, or some other type of CN (e.g., as illustrated in reference to FIGS. 1B-1C). In this aspect, the S1 interface 113 is split into two parts: the Sl-U interface 114, which carries traffic data between the RAN nodes 111 and 112 and the serving gateway (S-GW) 122, and the Sl-mobility management entity (MME) interface 115, which is a signaling interface between the RAN nodes 111 and 112 and MMEs 121.

[0028] In this aspect, the CN 120 comprises the MMEs 121, the S-GW 122, the Packet Data Network (PDN) Gateway (P-GW) 123, and a home subscriber server (HSS) 124. The MMEs 121 may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs 121 may manage mobility aspects in access such as gateway selection and tracking area list management. The HSS 124 may comprise a database for network users, including subscription-related information to support the network entities' handling of communication sessions. The CN 120 may comprise one or several HSSs 124, depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS 124 can provide support for routing/roaming, authentication, authorization, naming/addressing resolution, location dependencies, etc.

[0029] The S-GW 122 may terminate the SI interface 113 towards the RAN 110, and routes data packets between the RAN 110 and the CN 120. In addition, the S-GW 122 may be a local mobility anchor point for inter-RAN node handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities of the S-GW 122 may include a lawful intercept, charging, and some policy enforcement.

[0030] The P-GW 123 may terminate an SGi interface toward a PDN. The P-GW 123 may route data packets between the CN 120 and external networks such as a network including the application server 184 (alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface 125. The P-GW 123 can also communicate data to other external networks

131 A, which can include the Internet, IP multimedia subsystem (IPS) network, and other networks. Generally, the application server 184 may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). In this aspect, the P-GW 123 is shown to be communicatively coupled to an application server 184 via an IP interface 125. The application server 184 can also be configured to support one or more communication services (e.g., Voice-over-Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc.) for the UEs 101 and 102 via the CN 120.

[0031] The P-GW 123 may further be a node for policy enforcement and charging data collection. Policy and Charging Rules Function (PCRF) 126 is the policy and charging control element of the CN 120. In a non-roaming scenario, in some aspects, there may be a single PCRF in the Home Public Land Mobile Network (HPLMN) associated with a UE's Internet Protocol Connectivity Access Network (IP-CAN) session. In a roaming scenario with a local breakout of traffic, there may be two PCRFs associated with a UE's IP-CAN session: a Home PCRF (H-PCRF) within an HPLMN and a Visited PCRF (V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF 126 may be communicatively coupled to the application server 184 via the P-GW 123.

[0032] In some aspects, the communication network 140 A can be an loT network or a 5G or 6G network, including 5G new radio network using communications in the licensed (5GNR) and the unlicensed (5GNR-U) spectrum. One of the current enablers of loT is the narrowband-IoT (NB-IoT). Operation in the unlicensed spectrum may include dual connectivity (DC) operation and the standalone LTE system in the unlicensed spectrum, according to which LTE-based technology solely operates in unlicensed spectrum without the use of an “anchor” in the licensed spectrum, called MulteFire. Further enhanced operation of LTE systems in the licensed as well as unlicensed spectrum is expected in future releases and 5G systems. Such enhanced operations can include techniques for sidelink resource allocation and UE processing behaviors for NR sidelink V2X communications.

[0033] An NG system architecture (or 6G system architecture) can include the RAN 110 and a 5G core network (5GC) 120. The NG-RAN 110 can include a plurality of nodes, such as gNBs and NG-eNBs. The CN 120 (e.g., a 5G core network/5GC) can include an access and mobility function (AMF) and/or a user plane function (UPF). The AMF and the UPF can be communicatively coupled to the gNBs and the NG-eNBs via NG interfaces. More specifically, in some aspects, the gNBs and the NG-eNBs can be connected to the AMF by NG-C interfaces, and to the UPF by NG-U interfaces. The gNBs and the NG-eNBs can be coupled to each other via Xn interfaces. [0034] In some aspects, the NG system architecture can use reference points between various nodes. In some aspects, each of the gNBs and the NG- eNBs can be implemented as a base station, a mobile edge server, a small cell, a home eNB, and so forth. In some aspects, a gNB can be a master node (MN) and NG-eNB can be a secondary node (SN) in a 5G architecture.

[0035] FIG. IB illustrates a non-roaming 5G system architecture in accordance with some aspects. In particular, FIG. IB illustrates a 5G system architecture 140B in a reference point representation, which may be extended to a 6G system architecture. More specifically, UE 102 can be in communication with RAN 110 as well as one or more other 5GC network entities. The 5G system architecture 140B includes a plurality of network functions (NFs), such as an AMF 132, session management function (SMF) 136, policy control function (PCF) 148, application function (AF) 150, UPF 134, network slice selection function (NSSF) 142, authentication server function (AUSF) 144, and unified data management (UDM)/home subscriber server (HSS) 146.

[0036] The UPF 134 can provide a connection to a data network (DN)

152, which can include, for example, operator services, Internet access, or third- party services. The AMF 132 can be used to manage access control and mobility and can also include network slice selection functionality. The AMF 132 may provide UE-based authentication, authorization, mobility management, etc., and may be independent of the access technologies. The SMF 136 can be configured to set up and manage various sessions according to network policy. The SMF 136 may thus be responsible for session management and allocation of IP addresses to UEs. The SMF 136 may also select and control the UPF 134 for data transfer. The SMF 136 may be associated with a single session of a UE 101 or multiple sessions of the UE 101. This is to say that the UE 101 may have multiple 5G sessions. Different SMFs may be allocated to each session. The use of different SMFs may permit each session to be individually managed. As a consequence, the functionalities of each session may be independent of each other.

[0037] The UPF 134 can be deployed in one or more configurations according to the desired service type and may be connected with a data network. The PCF 148 can be configured to provide a policy framework using network slicing, mobility management, and roaming (similar to PCRF in a 4G communication system). The UDM can be configured to store subscriber profiles and data (similar to an HSS in a 4G communication system).

[0038] The AF 150 may provide information on the packet flow to the

PCF 148 responsible for policy control to support a desired QoS. The PCF 148 may set mobility and session management policies for the UE 101. To this end, the PCF 148 may use the packet flow information to determine the appropriate policies for proper operation of the AMF 132 and SMF 136. The AUSF 144 may store data for UE authentication.

[0039] In some aspects, the 5G system architecture 140B includes an IP multimedia subsystem (IMS) 168B as well as a plurality of IP multimedia core network subsystem entities, such as call session control functions (CSCFs). More specifically, the IMS 168B includes a CSCF, which can act as a proxy CSCF (P-CSCF) 162BE, a serving CSCF (S-CSCF) 164B, an emergency CSCF (E-CSCF) (not illustrated in FIG. IB), or interrogating CSCF (I-CSCF) 166B. The P-CSCF 162B can be configured to be the first contact point for the UE 102 within the IM subsystem (IMS) 168B. The S-CSCF 164B can be configured to handle the session states in the network, and the E-CSCF can be configured to handle certain aspects of emergency sessions such as routing an emergency request to the correct emergency center or PSAP. The I-CSCF 166B can be configured to function as the contact point within an operator's network for all IMS connections destined to a subscriber of that network operator, or a roaming subscriber currently located within that network operator's service area. In some aspects, the I-CSCF 166B can be connected to another IP multimedia network 170E, e.g. an IMS operated by a different network operator.

[0040] In some aspects, the UDM/HSS 146 can be coupled to an application server 160E, which can include a telephony application server (TAS) or another application server (AS). The AS 160B can be coupled to the IMS 168B via the S-CSCF 164B or the I-CSCF 166B.

[0041] A reference point representation shows that interaction can exist between corresponding NF services. For example, FIG. IB illustrates the following reference points: N1 (between the UE 102 and the AMF 132), N2 (between the RAN 110 and the AMF 132), N3 (between the RAN 110 and the UPF 134), N4 (between the SMF 136 and the UPF 134), N5 (between the PCF 148 and the AF 150, not shown), N6 (between the UPF 134 and the DN 152), N7 (between the SMF 136 and the PCF 148, not shown), N8 (between the UDM 146 and the AMF 132, not shown), N9 (between two UPFs 134, not shown), N10 (between the UDM 146 and the SMF 136, not shown), Nl 1 (between the AMF 132 and the SMF 136, not shown), N12 (between the AUSF 144 and the AMF 132, not shown), N13 (between the AUSF 144 and the UDM 146, not shown), N14 (between two AMFs 132, not shown), N15 (between the PCF 148 and the AMF 132 in case of a non-roaming scenario, or between the PCF 148 and a visited network and AMF 132 in case of a roaming scenario, not shown), N16 (between two SMFs, not shown), and N22 (between AMF 132 and NSSF 142, not shown). Other reference point representations not shown in FIG. 1B can also be used.

[0042] FIG. 1C illustrates a 5G system architecture 140C and a service- based representation. In addition to the network entities illustrated in FIG. IB, system architecture 140C can also include a network exposure function (NEF) 154 and a network repository function (NRF) 156. In some aspects, 5G system architectures can be service-based and interaction between network functions can be represented by corresponding point-to-point reference points Ni or as service-based interfaces.

[0043] In some aspects, as illustrated in FIG. 1C, service-based representations can be used to represent network functions within the control plane that enable other authorized network functions to access their services. In this regard, 5G system architecture 140C can include the following service-based interfaces: Namf 158H (a service-based interface exhibited by the AMF 132), Nsmf 1581 (a service-based interface exhibited by the SMF 136), Nnef 158B (a service-based interface exhibited by the NEF 154), Npcf 158D (a service-based interface exhibited by the PCF 148), aNudm 158E (a service-based interface exhibited by the UDM 146), Naf 158F (a service-based interface exhibited by the AF 150), Nnrf 158C (a service-based interface exhibited by the NRF 156), Nnssf 158A (a service-based interface exhibited by the NSSF 142), Nausf 158G (a service-based interface exhibited by the AUSF 144). Other service-based interfaces (e.g., Nudr, N5g-eir, and Nudsf) not shown in FIG. 1C can also be used.

[0044] NR-V2X architectures may support high-reliability low latency sidelink communications with a variety of traffic patterns, including periodic and aperiodic communications with random packet arrival time and size. Techniques disclosed herein can be used for supporting high reliability in distributed communication systems with dynamic topologies, including sidelink NR V2X communication systems.

[0045] FIG. 2 illustrates a block diagram of a communication device in accordance with some embodiments. The communication device 200 may be a UE such as a specialized computer, a personal or laptop computer (PC), a tablet PC, or a smart phone, dedicated network equipment such as an eNB, a server running software to configure the server to operate as a network device, a virtual device, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine. For example, the communication device 200 may be implemented as one or more of the devices shown in FIGS. 1A-1C. Note that communications described herein may be encoded before transmission by the transmitting entity (e.g., UE, gNB) for reception by the receiving entity (e.g., gNB, UE) and decoded after reception by the receiving entity.

[0046] Examples, as described herein, may include, or may operate on, logic or a number of components, modules, or mechanisms. Modules and components are tangible entities (e.g., hardware) capable of performing specified operations and may be configured or arranged in a certain manner. In an example, circuits may be arranged (e.g., internally or with respect to external entities such as other circuits) in a specified manner as a module. In an example, the whole or part of one or more computer systems (e.g., a standalone, client or server computer system) or one or more hardware processors may be configured by firmware or software (e.g., instructions, an application portion, or an application) as a module that operates to perform specified operations. In an example, the software may reside on a machine readable medium. In an example, the software, when executed by the underlying hardware of the module, causes the hardware to perform the specified operations. [0047] Accordingly, the term “module” (and “component”) is understood to encompass a tangible entity, be that an entity that is physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., transitorily) configured (e.g., programmed) to operate in a specified manner or to perform part or all of any operation described herein. Considering examples in which modules are temporarily configured, each of the modules need not be instantiated at any one moment in time. For example, where the modules comprise a general-purpose hardware processor configured using software, the general-purpose hardware processor may be configured as respective different modules at different times. Software may accordingly configure a hardware processor, for example, to constitute a particular module at one instance of time and to constitute a different module at a different instance of time.

[0048] The communication device 200 may include a hardware processor (or equivalently processing circuitry) 202 (e.g., a central processing unit (CPU), a GPU, a hardware processor core, or any combination thereof), a main memoiy 204 and a static memoiy 206, some or all of which may communicate with each other via an interlink (e.g., bus) 208. The main memory 204 may contain any or all of removable storage and non-removable storage, volatile memory or non-volatile memory. The communication device 200 may further include a display unit 210 such as a video display, an alphanumeric input device 212 (e.g., a keyboard), and a user interface (UI) navigation device 214 (e.g., a mouse). In an example, the display unit 210, input device 212 and UI navigation device 214 may be a touch screen display. The communication device 200 may additionally include a storage device (e.g., drive unit) 216, a signal generation device 218 (e.g., a speaker), a network interface device 220, and one or more sensors, such as a global positioning system (GPS) sensor, compass, accelerometer, or other sensor. The communication device 200 may further include an output controller, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.).

[0049] The storage device 216 may include a non-transitory machine readable medium 222 (hereinafter simply referred to as machine readable medium) on which is stored one or more sets of data structures or instructions 224 (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The instructions 224 may also reside, completely or at least partially, within the main memory 204, within static memory 206, and/or within the hardware processor 202 during execution thereof by the communication device 200. While the machine readable medium 222 is illustrated as a single medium, the term "machine readable medium" may include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) configured to store the one or more instructions 224.

[0050] The term “machine readable medium” may include any medium that is capable of storing, encoding, or carrying instructions for execution by the communication device 200 and that cause the communication device 200 to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non-limiting machine readable medium examples may include solid-state memories, and optical and magnetic media. Specific examples of machine readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; Random Access Memory (RAM); and CD-ROM and DVD-ROM disks.

[0051] The instructions 224 may further be transmitted or received over a communications network using a transmission medium 226 via the network interface device 220 utilizing any one of a number of wireless local area network (WLAN) transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone networks (e.g., cellular networks), Plain Old Telephone (POTS) networks, and wireless data networks. Communications over the networks may include one or more different protocols, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards known as Wi-Fi, IEEE 802.16 family of standards known as WiMax, IEEE 802.15.4 family of standards, a Long Term Evolution (LTE) family of standards, a Universal Mobile Telecommunications System (UMTS) family of standards, peer-to-peer (P2P) networks, a next generation (NG)/5 ^th generation (5G) standards among others. In an example, the network interface device 220 may include one or more physical jacks (e.g., Ethernet, coaxial, or phonejacks) or one or more antennas to connect to the transmission medium 226.

[0052] Note that the term “circuitry” as used herein refers to, is part of, or includes hardware components such as an electronic circuit, a logic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group), an Application Specific Integrated Circuit (ASIC), a field-programmable device (FPD) (e.g., a field-programmable gate array (FPGA), a programmable logic device (PLD), a complex PLD (CPLD), a high-capacity PLD (HCPLD), a structured ASIC, or a programmable SoC), digital signal processors (DSPs), etc., that are configured to provide the described functionality. In some embodiments, the circuitry may execute one or more software or firmware programs to provide at least some of the described functionality. The term “circuitry” may also refer to a combination of one or more hardware elements (or a combination of circuits used in an electrical or electronic system) with the program code used to carry out the functionality of that program code. In these embodiments, the combination of hardware elements and program code may be referred to as a particular type of circuitry.

[0053] The term “processor circuitry” or “processor” as used herein thus refers to, is part of, or includes circuitry capable of sequentially and automatically carrying out a sequence of arithmetic or logical operations, or recording, storing, and/or transferring digital data. The term “processor circuitry” or “processor” may refer to one or more application processors, one or more baseband processors, a physical central processing unit (CPU), a single- or multi-core processor, and/or any other device capable of executing or otherwise operating computer-executable instructions, such as program code, software modules, and/or functional processes. [0054] Any of the radio links described herein may operate according to any one or more of the following radio communication technologies and/or standards including but not limited to: a Global System for Mobile Communications (GSM) radio communication technology, a General Packet Radio Service (GPRS) radio communication technology, an Enhanced Data Rates for GSM Evolution (EDGE) radio communication technology, and/or a Third Generation Partnership Project (3GPP) radio communication technology, for example Universal Mobile Telecommunications System (UMTS), Freedom of Multimedia Access (FOMA), 3GPP Long Term Evolution (LTE), 3GPP Long Term Evolution Advanced (LTE Advanced), Code division multiple access 2000 (CDMA2000), Cellular Digital Packet Data (CDPD), Mobitex, Third Generation (3G), Circuit Switched Data (CSD), High-Speed Circuit-Switched Data (HSCSD), Universal Mobile Telecommunications System (Third Generation) (UMTS (3G)), Wideband Code Division Multiple Access (Universal Mobile Telecommunications System) (W-CDMA (UMTS)), High Speed Packet Access (HSPA), High-Speed Downlink Packet Access (HSDPA), High-Speed Uplink Packet Access (HSUPA), High Speed Packet Access Plus (HSPA+), Universal Mobile Telecommunications System-Time-Division Duplex (UMTS-TDD), Time Division-Code Division Multiple Access (TD-CDMA), Time Division- Synchronous Code Division Multiple Access (TD-CDMA), 3rd Generation Partnership Project Release 8 (Pre-4th Generation) (3GPP Rel. 8 (Pre-4G)), 3GPP ReL 9 (3rd Generation Partnership Project Release 9), 3GPP Rel. 10 (3rd Generation Partnership Project Release 10) , 3GPP Rel. 11 (3rd Generation Partnership Project Release 11), 3GPP Rel. 12 (3rd Generation Partnership Project Release 12), 3GPP Rel. 13 (3rd Generation Partnership Project Release 13), 3GPP Rel. 14 (3rd Generation Partnership Project Release 14), 3GPP Rel. 15 (3rd Generation Partnership Project Release 15), 3GPP Rel. 16 (3rd Generation Partnership Project Release 16), 3GPP Rel. 17 (3rd Generation Partnership Project Release 17) and subsequent Releases (such as Rel. 18, Rel. 19, etc.), 3GPP 5G, 5G, 5G New Radio (5G NR), 3GPP 5G New Radio, 3GPP LTE Extra, LTE-Advanced Pro, LTE Licensed-Assisted Access (LAA), MuLTEfire, UMTS Terrestrial Radio Access (UTRA), Evolved UMTS Terrestrial Radio Access (E-UTRA), Long Term Evolution Advanced (4th Generation) (LTE Advanced (4G)), cdmaOne (2G), Code division multiple access 2000 (Third generation) (CDMA2000 (3G)), Evolution-Data Optimized or Evolution-Data Only (EV-DO), Advanced Mobile Phone System (1st Generation) (AMPS (1G)), Total Access Communication System/Extended Total Access Communication System (TACS/ETACS), Digital AMPS (2nd Generation) (D-AMPS (2G)), Push-to-talk (PTT), Mobile Telephone System (MTS), Improved Mobile Telephone System (IMTS), Advanced Mobile Telephone System (AMTS), OLT (Norwegian for Offentlig Landmobil Telefoni, Public Land Mobile Telephony), MTD (Swedish abbreviation for Mobiltelefonisystem D, or Mobile telephony system D), Public Automated Land Mobile (Autotel/PALM), ARP (Finnish for Autoradiopuhelin, "car radio phone"), NMT (Nordic Mobile Telephony), High capacity version of NTT (Nippon Telegraph and Telephone) (Hicap), Cellular Digital Packet Data (CDPD), Mobitex, DataTAC, Integrated Digital Enhanced Network (iDEN), Personal Digital Cellular (PDC), Circuit Switched Data (CSD), Personal Handy- phone System (PHS), Wideband Integrated Digital Enhanced Network (WiDEN), iBurst, Unlicensed Mobile Access (UMA), also referred to as also referred to as 3GPP Generic Access Network, or GAN standard), Zigbee, Bluetooth(r), Wireless Gigabit Alliance (WiGig) standard, mmWave standards in general (wireless systems operating at 10-300 GHz and above such as WiGig, IEEE 802.11ad, IEEE 802.1 lay, etc.), technologies operating above 300 GHz and THz bands, (3GPP/LTE based or IEEE 802.1 Ip or IEEE 802.1 Ibd and other) Vehicle-to-Vehicle (V2V) and Vehicle-to-X (V2X) and Vehicle-to- Infrastructure (V2I) and Infrastructure-to-Vehicle (I2V) communication technologies, 3GPP cellular V2X, DSRC (Dedicated Short Range Communications) communication systems such as Intelligent-Transport-Systems and others (typically operating in 5850 MHz to 5925 MHz or above (typically up to 5935 MHz following change proposals in CEPT Report 71)), the European ITS-G5 system (i.e. the European flavor of IEEE 802.1 Ip based DSRC, including TTS-G5A (i.e., Operation of ITS-G5 in European ITS frequency bands dedicated to ITS for safety re-lated applications in the frequency range 5,875 GHz to 5,905 GHz), ITS-G5B (i.e., Operation in European ITS frequency bands dedicated to ITS non- safety applications in the frequency range 5,855 GHz to 5,875 GHz), ITS-G5C (i.e., Operation of ITS applications in the frequency range 5,470 GHz to 5,725 GHz)), DSRC in Japan in the 700MHz band (including 715 MHz to 725 MHz), IEEE 802.1 Ibd based systems, etc.

[0055] Aspects described herein can be used in the context of any spectrum management scheme including dedicated licensed spectrum, unlicensed spectrum, license exempt spectrum, (licensed) shared spectrum (such as LSA = Licensed Shared Access in 2.3-2.4 GHz, 3.4-3.6 GHz, 3.6-3.8 GHz and further frequencies and SAS = Spectrum Access System / CBRS = Citizen Broadband Radio System in 3.55-3.7 GHz and further frequencies). Applicable spectrum bands include IMT (International Mobile Telecommunications) spectrum as well as other types of spectrum/bands, such as bands with national allocation (including 450 - 470 MHz, 902-928 MHz (note: allocated for example in US (FCC Part 15)), 863-868.6 MHz (note: allocated for example in European Union (ETSI EN 300220)), 915.9-929.7 MHz (note: allocated for example in Japan), 917-923.5 MHz (note: allocated for example in South Korea), 755-779 MHz and 779-787 MHz (note: allocated for example in China), 790 - 960 MHz, 1710 - 2025 MHz, 2110 - 2200 MHz, 2300 - 2400 MHz, 2.4-2.4835 GHz (note: it is an ISM band with global availability and it is used by Wi-Fi technology family (1 Ib/g/n/ax) and also by Bluetooth), 2500 - 2690 MHz, 698-790 MHz, 610 - 790 MHz, 3400 - 3600 MHz, 3400 - 3800 MHz, 3800 - 4200 MHz, 3.55- 3.7 GHz (note: allocated for example in the US for Citizen Broadband Radio Service), 5.15-5.25 GHz and 5.25-5.35 GHz and 5.47-5.725 GHz and 5.725-5.85 GHz bands (note: allocated for example in the US (FCC part 15), consists four U-NII bands in total 500 MHz spectrum), 5.725-5.875 GHz (note: allocated for example in EU (ETSI EN 301 893)), 5.47-5.65 GHz (note: allocated for example in South Korea, 5925-7125 MHz and 5925-6425MHz band (note: under consideration in US and EU, respectively. Next generation Wi-Fi system is expected to include the 6 GHz spectrum as operating band but it is noted that, as of December 2017, Wi-Fi system is not yet allowed in this band. Regulation is expected to be finished in 2019-2020 time frame), IMT-advanced spectrum, IMT-2020 spectrum (expected to include 3600-3800 MHz, 3800 - 4200 MHz, 3.5 GHz bands, 700 MHz bands, bands within the 24.25-86 GHz range, etc.), spectrum made available under FCC's "Spectrum Frontier" 5G initiative (including 27.5 - 28.35 GHz, 29.1 - 29.25 GHz, 31 - 31.3 GHz, 37 - 38.6 GHz, 38.6 - 40 GHz, 42 - 42.5 GHz, 57 - 64 GHz, 71 - 76 GHz, 81 - 86 GHz and 92 - 94 GHz, etc), the ITS (Intelligent Transport Systems) band of 5.9 GHz (typically 5.85-5.925 GHz) and 63-64 GHz, bands currently allocated to WiGig such as WiGig Band 1 (57.24-59.40 GHz), WiGig Band 2 (59.40-61.56 GHz) and WiGig Band 3 (61.56-63.72 GHz) and WiGig Band 4 (63.72-65.88 GHz), 57- 64/66 GHz (note: this band has near-global designation for Multi-Gigabit Wireless Systems (MGWS)/WiGig . In US (FCC part 15) allocates total 14 GHz spectrum, while EU (ETSI EN 302 567 and ETSI EN 301 217-2 for fixed P2P) allocates total 9 GHz spectrum), the 70.2 GHz - 71 GHz band, any band between 65.88 GHz and 71 GHz, bands currently allocated to automotive radar applications such as 76-81 GHz, and future bands including 94-300 GHz and above. Furthermore, the scheme can be used on a secondary basis on bands such as the TV White Space bands (typically below 790 MHz) where in particular the 400 MHz and 700 MHz bands are promising candidates. Besides cellular applications, specific applications for vertical markets may be addressed such as PMSE (Program Making and Special Events), medical, health, surgery, automotive, low-latency, drones, etc. applications.

[0056] Aspects described herein can also implement a hierarchical application of the scheme is possible, e.g., by introducing a hierarchical prioritization of usage for different types of users (e.g., low/medium/high priority, etc.), based on a prioritized access to the spectrum e.g., with highest priority to tier-1 users, followed by tier-2, then tier-3, etc. users, etc.

[0057] Aspects described herein can also be applied to different Single Carrier or OFDM flavors (CP-OFDM, SC-FDMA, SC-OFDM, filter bank-based multicarrier (FBMC), OFDMA, etc.) and in particular 3GPP NR (New Radio) by allocating the OFDM carrier data bit vectors to the corresponding symbol resources.

[0058] Some of the features are defined for the network side, such as

APs, eNBs, NR or gNBs - note that this term is typically used in the context of 3GPP 5G and 6G communication systems, etc. Still, a UE may take this role as well and act as an AP, eNB, or gNB; that is some or all features defined for network equipment may be implemented by a UE. [0059] As above, 6G wireless systems are expected to provide better user experience and performance compared to prior wireless technologies (e.g., LTE and 5G). Target key performance indicators (KPIs) include supporting wider bandwidths compared to 5G (e.g., at least 2 GHz or larger), supporting higher peak data rates (such as beyond 100 Gbps), and providing lower physical layer latency (such as under 100 μsec turnaround time). 6G is also expected to enable better support of vertical industries, including support for private networks.

[0060] In addition to the distinguishing target KPIs, other system design criteria make 6G distinct from prior technologies. In the current cellular systems (e.g., 3G, LTE and 5GNR), providing ubiquitous network coverage has been a prime criterion to ensure that network coverage is almost always available everywhere within the network. As such, system design development from different perspectives has been based on the assumption of ubiquitous coverage in the network. However, for future technology design, network coverage may not be assumed ubiquitously available within the network. The limited network coverage in future technologies can have different dimensions and can be due to different reasons. For example, a sparse vertical deployment, e.g., in factory environment, private networks, etc., may be desired to save deployment costs. For instance, a small number of cells may be deployed to only cover certain hotspot areas, while most of other areas may be kept as blank spots. The mobility of users (or potentially the access point(s)) may also result in a more pronounced coverage loss experience.

[0061] In the conventional cellular system design, the normal trend to provide ubiquitous coverage has been supported via network densifi cation, relying on non-standalone (NSA) operation with full master cell coverage, e.g., through dual-connectivity (DC) and carrier aggregation (CA) techniques, etc. However, such solutions may not be always possible and/or desired in the futuristic system design. Particularly, it may not be possible or desired to rely on the network coverage provided by other cells or other access technologies. As such, with no continuous cell deployment, when the UE goes out of (i.e., exits) coverage of one cell, the UE may not fall within the coverage of another neighboring cell to which to connect. Considering potentially limited coverage standalone deployments, the duration that a mobile UE may spend within the network coverage can be transient.

[0062] On the other hand, a key enabler in 6G, is operation in high- frequency spectrum, i.e., THz band. Although high-frequency bands can provide promising large bandwidths to support high data-rate data transfer, such high- frequency bands come with many challenges due to the nature of the wireless channel in those frequencies. These challenges include high pathloss and penetration loss, very short communication/coverage range, and frequent blockages. Accordingly, for high-band operation without special handling to completely avoid blockage, the system design should inherently address short term or longer periods of blockage. The high-band characteristics and needs further exacerbate the challenge of data transfer during the transient in-coverage durations. Particularly, although a deployment of cells has a nominal coverage area, even within that (potentially sparse) coverage area, the transmission channel may be frequently blocked due to stationary and/or mobile blocking objects. Blockages occur due to link instability and are normally expected to have shorter duration than out of coverage events; however, the blockage duration may still be significant compared to the overall transient in-coverage duration.

[0063] As such, it is desirable to design a system to identify and efficiently handle challenges due to limited coverage as well as blockages. Particularly, it is desirable to increase the system reactiveness and proactiveness, to detect and/or predict the communication barriers, and take proper actions. Thus, a system design to minimize connection establishment/re-establishment and network access time to allow the greatest amount of possible data transfer during the short in-coverage non-blocked durations, i.e., to enable the UE to quickly transfer and/or receive data whenever the link becomes available. Particularly, one of the goals of the future technology is to develop a system design that enables accessing the network and transferring uplink (UL) or downlink (DL) data (large or small payload) with the least possible incurred latency and overhead before the link becomes unavailable (likely in a very short time). Such design, called opportunistic access, involves both RAN and core network aspects. As such, the limitations, potential bottlenecks, and any room for enhancement or optimization of the current system design (from both control plane (CP) and user plane (UP) perspectives) are identified under limited coverage with potentially frequent link blockages within the nominal coverage area/duration.

[0064] In the current system design, the radio resource control idle (RRC_IDLE) state plays the role of a fallback state. For example, when the UE faces a radio link failure (RLF) event from which the UE is unable to recover or the UE goes out of network coverage, the UE enters the RRC_IDLE state. To transfer/receive data, the UE generally transitions to the RRC_CONNECTED state, although there are some exceptions for transmission of very small payload sizes in the RRC_INACTIVE state. However, the overhead and latency of idle- to-active transitions in the core network is not tolerable in scenarios in which the in-coverage duration of the UE is transient. In some embodiments, the RRC_INACTIVE state may be adjusted, such as being the fallback state, for operation under limited coverage (e.g., in deployments with coverage islands, etc.), to enable making better use of the transient time that the UE spends in network coverage. This is described in more detail in U.S. Provisional Patent App. No. 63/131,176, entitled “ENHANCEMENTS OF RADIO RESOURCE CONTROL (RRC) INACTIVE STATE IN NEXT GENERATION CELLULAR NETWORKS” filed December 28, 2020, which is incorporated by reference in its entirety.

[0065] Accordingly, cell search and cell selection procedures and their triggers/requirements are described to enable operation in sparse deployments with limited coverage and potentially frequent short-/long-term blockages within the nominal coverage area, and enable utilization of transient link-availabilities. In combination with the RRC_INACTIVE state being the fallback state, the embodiments herein enable meaningful operation in the aforementioned deployments, while also result in more efficient utilization of the link availability in any deployments, even those with less critical coverage and link-availability concerns. However, while the embodiments herein may be applicable to opportunistic access scenarios, the embodiments are not limited to such deployments/scenarios, and can be applicable to broader scenarios, deployments, and applications. [0066] RRC states and corresponding procedures

[0067] In wireless communication systems, the UE may reside in different states depending on the traffic activity. The core network states CM_IDLE and CM_CONNECTED are defined based on whether or not the UE has established a connection with the core network. FIG. 3 illustrates 5G NR CP state transitions in accordance with some aspects. An NR device can be in one of three RRC states, RRC_IDLE, RRC_CONNECTED, and RRC_INACTIVE. FIG. 4A illustrates 5G NR RRC state transitions in accordance with some aspects. FIG. 4B illustrates 5GNR RRC states of the RRC state transitions in FIG. 4A in accordance with some aspects. The mobility, handover, and corresponding measurements aspects have not been mentioned in FIG. 4A or 4B. [0068] In the RRC_IDLE state, there is no RRC context (i.e., the parameters for communication between the UE and the network) in the RAN, and the UE does not belong to a specific cell. From a core network perspective, the device is in the CM_IDLE state. No data transfer may take place as the UE sleeps most of the time to reduce battery consumption. In the downlink, a UE in the idle state periodically wakes up to receive paging messages, if any, from the network. Uplink synchronization is not maintained and hence the only uplink transmission activity that may take place is random access, to move to a connected state. As part of moving to a connected state, the RRC context is established in both the UE and the network.

[0069] In the RRC_CONNECTED state, the RRC context is established and parameters used for communication between the UE and the radio-access network are known to both entities. From a core network perspective, the UE is in the CM_CONNECTED state. The cell to which the UE belongs is known and an identity of the UE, the Cell Radio-Network Temporary Identifier (C-RNTI), used for signaling purposes between the UE and the network, has been configured. The connected state is intended for data transfer to/from the UE. Uplink time alignment may or may not exist but are established using random access and maintained for data transmission to take place.

[0070] In the RRC_INACTIVE state, the UE context is kept in both the UE and the gNB. The core network connection is also kept, that is, the UE is in the CM_CONNECTED state from a core network perspective. Hence, transition to a connected state for data transfer is fast. No core network signaling is used; in terms of messaging, only Resume Request and Resume messages are exchanged, upon which the UE enters the RRC_CONNECTED state. The RRC context is already in place in the network and idle-to-active transitions can be handled in the radio-access network. Different from the RRC_IDLE state, in the RRC_INACTIVE state, the UE is expected to monitor broadcast downlink signals (system information, paging, etc.) as part of physical downlink control channel (PDCCH) monitoring just like in the RRC_CONNECTED state.

[0071] UE states in the RRC_IDLE and RRC_INACTIVE states in NR

[0072] A UE in the RRC_IDLE or RRC_INACTIVE state, can be in different (sub-)states: ‘Any cell selection’ state refers to a UE that is out of network coverage and is not associated with a serving cell on any carrier, as defined in 3GPP TS 38.304. This state is applicable for the RRC_IDLE state and RRC_INACTIVE state. In this state, the UE performs cell selection to find a suitable cell (one for which the measured cell attributes satisfy cell selection criteria). If the cell selection process fails to find a suitable cell after a complete scan of all RATs and all frequency bands supported by the UE, the UE attempts to find an acceptable cell (one for which the measured cell attributes satisfy cell selection criteria and the cell is not barred) of any PLMN to camp on, trying all RATs that are supported by the UE and searching first for a high-quality cell (defined in clause 5.1.1.2 of TS 38.304). The UE, which is not camped on any cell, remains in this state.

[0073] According to TS 28.133, if a UE in the RRC_IDLE state has not found any new suitable cell based on searches and measurements using the intra- frequency, inter-frequency and inter-RAT information indicated in the system information for 10s, the UE initiates cell selection procedures for the selected PLMN as defined in TS 38.304. This may be interpreted as the UE performing the “cell reselection evaluation process” for 10s and if not successful, goes to “Any cell selection". FIG. 5 illustrates RRC_IDLE and RRC_INACTIVE Cell Selection and Reselection in accordance with some aspects. The terms in quotes refer to the states in FIG. 5.

[0074] The ‘Camped Normally’ state is applicable for the RRC_IDLE and RRC_INACTIVE state. When camped normally, amongst other actions, the UE performs monitoring of paging channel of the cell according to information broadcast in SIB1, monitoring of Short Messages transmitted with the paging RNTI (P-RNTI) over downlink channel information (DCI), and relevant System Information (SI), etc. This state includes a period between cell selection criteria not being met and the UE entering the "any cell selection" state (See TS 38.133). [0075] The ‘Camped on Any Cell’ state is only applicable for the RRC_IDLE state. In this state, the UE performs monitoring of Short Messages transmitted with P-RNTI over DCI, monitoring of relevant System Information, and regularly attempting to find a suitable cell trying all frequencies of all RATs that are supported by the UE. If the UE supports voice services and the current cell does not support IMS emergency calls as indicated by the field ims- EmergencySupport in SIB1 as specified in TS 38.331, the UE performs cell selection/reselection to an acceptable cell that supports emergency calls in any supported RAT regardless of priorities provided in system information from current cell, if no suitable cell is found. If a suitable cell is found, the UE moves to the camped normally state.

[0076] A number of reasons exist for camping on a cell in the RRC_IDLE state and the RRC_INACTIVE state. Such camping enables the UE to receive system information from the public land mobile network (PLMN) or the Stand-alone Non-Public Network (SNPN). When registered, if the UE is to establish a new or resume a suspended RRC connection, the UE can do so by initially accessing the network on a control channel of the cell on which the UE is camped. If the network is to send a message or deliver data to the registered UE, the network knows (in most cases) the set of tracking areas (in the RRC_IDLE state) or RAN-based notification area (RNA) (in the RRC_INACTIVE state) in which the UE is camped. The network can then send a "paging" message for the UE on the control channels of all the cells in the corresponding set of areas. The UE then receives the paging message and can respond. The UE may receive Earthquake and Tsunami Warning System (ETWS) and Commercial Mobile Alert System (CMAS) notifications. As shown in FIG. 5, operation 1 is entered whenever a new PLMN selection or new SNPN selection is performed (TS 38.304).

[0077] UE procedures in the RRC_IDLE and RRC_INACTIVE state in NR

[0078] The RRC_IDLE state and RRC_INACTIVE state tasks can be subdivided into three processes: PLMN/SNPN selection, Cell selection, and Location registration and RNA update.

[0079] In PLMN selection (for a UE not operating in SNPN access mode) or SNPN selection (for UE operating in SNPN access mode), when a UE is switched on, a PLMN or a SNPN is selected by non-access stratum (NAS) - the UE NAS layer identifies a selected PLMN and equivalent PLMNs. For the selected PLMN/SNPN, one or more associated RAT(s) may be set, as specified in TS 23.122. The NAS provides a list of equivalent PLMNs, if available, that the access stratum (AS) uses for cell selection and cell reselection.

[0080] After a UE has switched on and a PLMN has been selected, a ‘cell selection’ process takes place, as described in TS 38.304. This process allows UE to select a suitable cell on which to camp to access available services. In this process, the UE can use stored information [for several RATs, if available] (Stored information cell selection, to expedite the process) or not (Initial cell selection). With cell selection, the UE searches for a suitable cell of the selected PLMN or selected SNPN, chooses that cell to provide available services, and monitors its control channel. This procedure is defined as "camping on the cell". The UE selects a suitable cell based on RRC_IDLE or RRC_INACTIVE state measurements and cell selection criteria. For cell selection in multi-beam operations, measurement quantity of a cell is up to UE implementation. In multi-beam operations, cell quality is derived amongst the beams corresponding to the same cell (TS 38.300 subclause 9.2).

[0081] If the new cell to be camped on does not belong to at least one tracking area to which the UE is registered, location registration is performed. In the RRC_INACTIVE state, if the new cell does not belong to the configured RNA, an RNA update procedure is performed. [0082] PLMN selection, SNPN selection, cell selection/reselection procedures, and location registration are common for both the RRC_IDLE state and RRC_INACTIVE state. The RNA update is only applicable for RRC_INACTIVE state.

[0083] If the UE loses coverage of the registered PLMN/SNPN, either a new PLMN/SNPN is selected automatically (automatic mode), or an indication of available PLMNs/SNPNs is given to the user so that a manual selection can be performed (manual mode). As part of manual SNPN selection, the AS reports available SNPN identifiers together with their Human-Readable Network Name (HRNN) (if broadcast) to the NAS. The functional division between UE NAS and UE AS in the RRC_IDLE state and RRC_INACTIVE states, for cell selection process, is indicated in the table below.

Background on cell selection principals and types in NR

[0084] Cell search and cell selection are based on Cell Defining (CD) signaling signal broadcasts (SSBs) located on a synchronization raster. A primary cell (PCell) is always associated to a CD-SSB located on the synchronization raster. Cell search is the procedure by which a UE acquires time and frequency synchronization with a cell and detects the Cell ID of that cell. NR cell search is based on the primary and secondary synchronization signals, and physical broadcast channel (PBCH) demodulation reference signals (DMRS), located on the synchronization raster. The possible SS block locations for each frequency band are a limited set of frequencies referred to as the synchronization raster. A UE searchs for an SS block within the set of synchronization raster.

[0085] Cell selection is performed by initial cell selection in which the UE has no prior knowledge of which RF channels are NR frequencies, cell selection leveraging stored information, or cell selection when leaving the RRC_CONNECTED mode.

[0086] During initial cell selection, the UE scans all RF channels in the NR bands (searches NR frequency bands) according to its capabilities to find a suitable cell. The UE may or may not search each carrier in turn as discussed below. On each carrier frequency, the UE searches for the strongest cell (except for operation with shared spectrum channel access where the UE may search for the next strongest cell(s)) as per CD-SSB. Once a suitable cell is found, this cell is selected - the UE then reads cell system info broadcast to identify its PLMN(s).

[0087] Cell selection leveraging stored information, which speeds up the procedure, uses stored information related to carrier frequencies (to shorten the search) and optionally also information on cell parameters retrieved from previously received measurement control information elements or from previously detected cells and pre-existing SI messages. Once the UE has found a suitable cell, the UE selects the cell. If no suitable cell is found, the initial cell selection procedure using initial cell selection is started.

[0088] Cell selection when leaving the RRC_CONNECTED mode applies to the UE transitioning to the RRC_IDLE or RRC_INACTIVE mode. The network can direct the UE towards a specific RF carrier by including ‘redirectedCarrierlnfo’ within the RRCRelease message; otherwise the UE is free to search any RF carrier.

[0089] To accelerate the cell search procedure, various smart UE implementations can be considered. For example, in cell search without stored information, the UE may not sequentially follow Global Synchronization Channel Number (GSCN), i.e., 1 candidate every X MHz, where X may be equal to 1.44MHz, etc. The UE may avoid brute force searching, via a smart receiver implementation. For example, through spectrum sensing, the receiver may enable a large bandwidth for sensing and senses (subsets) of spectrum. If the receiver detects an expected spectrum, e.g., a OFDM waveform look alike spectrum, the UE will search for a GSCN near the center of the detected spectrum. This enables the UE to quickly find potential candidates across wide bands by a divide-and-conquer approach and narrowing down the candidate frequencies. The extent of removing or de-prioritizing candidates depends on the used bandwidth at the receiver for sensing. Even with such improvements, the time for cell search may still be significant. Further, such implementations may also be challenging and may still use significant time for high carrier frequencies since the system bandwidths and total potential spectrum are very large.

[0090] On recovery from out of coverage, the UE seeks to identify a suitable cell (stored information or initial cell selection). If the UE is not able to identify a suitable cell (on any frequency or RAT), the UE seeks to identify an acceptable cell. When a suitable cell is found or if only an acceptable cell is found, the UE camps on that cell and commences a cell reselection procedure. [0091] On transition from the RRC_CONNECTED to RRC_IDLE state (e.g., after RLF declaration and initiating and failing RRC reestablishment), the UE may camp on the last cell for which the UE was in the RRC_CONNECTED state or a cell/any cell of set of cells or frequency be assigned by RRC in the state transition message (see TS 38.300). The UE performs cell selection using selection-related parameters from the system information or from a RRC Connection Release message received from the network (since RRC connection release procedure can also be used to release and redirect a UE to another frequency). If the UE is provided with a redirection in Release, the UE follows the redirection. Which type of cell selection the UE performs (e.g., with or without stored information), at what times, and how, are not specified, and left up to the UE implementation. It may be the case that the UE first attempts to select most recent cell on which the UE has camped in Connected mode, or the UE selects a Suitable Cell on a frequency that is allocated through the RRC Connection Release message (if included). If such a cell is not available, the UE may attempt to find a suitable cell by performing the Stored Information Cell Selection procedure. If the UE fails to find a suitable cell, the UE may perform the initial cell selection procedure. The primary function of cell selection is to ensure that the cell the UE is going to use is suitable.

[0092] Note that at reception of an RRCRelease message to transition the UE to the RRC_IDLE or RRC_INACTIVE state, the UE attempts to camp on a suitable cell according to redirectedCarrierlnfo if included in the RRCRelease message. If the UE cannot find a suitable cell, the UE is allowed to camp on any suitable cell of the indicated RAT. If the RRCRelease message does not contain the redirectedCarrierlnfo, the UE attempts to select a suitable cell on an NR carrier. If no suitable cell is found according to the above, the UE performs cell selection using stored information to find a suitable cell to camp on. When returning to the RRC_IDLE state after the UE moved to the RRC_CONNECTED state from the camped on any cell state, the UE attempts to camp on an acceptable cell according to redirectedCarrierlnfo, if included in the RRCRelease message. If the UE cannot find an acceptable cell, the UE is allowed to camp on any acceptable cell of the indicated RAT. If the RRCRelease message does not contain redirectedCarrierlnfo, the UE attempts to select an acceptable cell on an NR frequency. If no acceptable cell is found according to the above, the UE continues to search for an acceptable cell of any PLMN in state any cell selection (see TS 38.304, 5.2.6).

[0093] UE fallback state

[0094] It is expected that in future technologies, the RRC_IDLE state and CM_IDLE state may not be used. Currently, the fact that the RRC_IDLE state is deemed as the initial/reset state is carried over from the LTE design. Accordingly, whenever the UE faces an unsuccessful resume, an integrity check failure upon reestablishment, etc., the UE transitions into the RRC_IDLE state. On the other hand, the UE’s initial state has not been spelled out in the 3 GPP specification (TS 38.304). To this end, properly defining the UE (fallback/reset) state for operation under the limited coverage, e.g., upon entering cell’s coverage (likely only for a short duration, before exiting the network coverage again), may help to characterize the proper data transfer scheme. There are different considerations with respect to each state to define the fallback state. For example, if the UE stays in the RRC_CONNECTED state, upon an out-of- coverage event, the UE faces an unrecoverable RLF, which will end up in the RRC_IDLE state if the UE cannot find another cell (the case under the scenarios of interest in the context of opportunistic access). When the UE cannot find any cell and the reestablishment fails, then the UE enters the RRC_IDLE state and performs a NAS recovery, where the UE will continue to find a cell, and as soon as the UE finds one, triggers either a service request or a tracking area update. [0095] In current technologies, a common Reestablishment procedure is defined for all scenarios. Further, optimization of the RRC reestablishment procedure (compared to LTE) is lacking since generally the UE is assumed to be in coverage. Also, facing an RLF is a very rare situation/event. As such, the expectation has been that even if the UE faces an RLF on one cell, the UE will find another cell during cell selection in which to perform a reestablishment. However, this expectation may not hold for future technology design in envisioned sparse deployments potentially in high bands.

[0096] On the other hand, if the UE stays in RRC_INACTIVE state, the price is the network’s configuration resources. As gNBs are distributed units with limited memory, in a wide-area deployment potentially with large number of gNB, populating all gNBs with large memory is a significant cost; but for small area deployment, cost of memory may not be an issue. Also, with a central unit/distributed unit (CU/DU) split, the memory in the CU may not be a significant issue. If resources are critical, radio delay due to RRC_IDLE to RRC_CONNECTED state transition may occur, in which case reduced delay may be designed. If the UE moves to another gNB, the new gNB fetches/ retrieves the UE context from the previous gNB. This can be done using a resume ID, which is unique within the RAN. The delay is due to the context fetch and potential inter-gNB handover latency.

[0097] As the cost of transitioning from the RRC_INACTIVE to RRC_CONNECTED state (the amount of signaling exchange from the RRC_INACTIVE to RRC_CONNECTED state) is negligible, keeping the UE in RRC_INACTIVE state, even when the UE moves to out of network’s coverage in sparse deployments with limited coverage, may be reasonable. Accordingly, when the UE comes back into the network coverage, only a single message is exchanged to retrieve the old configuration. As such, in scenarios where the UE is expected to come back to the network coverage at a later time, the resources may be kept suspended, at the cost of some network inefficiency (depending on the number of UEs to support opportunistic access). Thus, the RRC_INACTIVE state may be set as the fallback/reset state to enable the UE to stay in RRC_INACTIVE state even when going out of coverage, to address the requirements, etc., for operation under limited coverage and make best use of the transient time that the UE is in coverage.

[0098] By introducing an extended INACTIVE state and/or defining the RRC_INACTIVE as the fallback state, when the UE is in the RRC_INACTIVE state and is out of the cell’s coverage, the network does not release the UE context/configurations. That is, the UE maintains the context, last connected cell, time stamp/location for when the UE goes out of coverage. Accordingly, cell search/cell selection procedures, as well as their requirements and triggers (e.g., from current or future’s RRC_IDLE/RRC_INACTIVE states) are (re-)defmed.

[0099] The current NR design and requirements of cell selection likely do not allow for operation in sparse deployments with limited coverage and potentially frequent short/long term link blockages within the nominal coverage area. Given that most of cell selection design aspects and UE behavior (e.g., when the UE goes out of the coverage area and comes back to the coverage, etc.) are left up to the UE implementation, it is not possible to accurately quantify the incurred latency (required time) to perform the cell selection procedure.

However, it is known that for initial cell selection, the cell search and frequency scanning process consumes a significant amount of time, which can be even larger than the total amount of time a mobile UE may spend in the coverage area with high-band (non-blocked) link availability. In order to provide high-level insight, the time for the UE to complete cell search may be roughly estimated as Nfreq*Tsearch for cell search without stored information, where Nfreq is the number of candidate frequencies the UE is to scan and Tsearch is the time to select a cell (e.g., latency of cell selection and initial beam acquisition in addition to the latency of SIB1 acquisition). Both the Nfreq and Tsearch values can be relatively large numbers, especially for a beam-centric design with beam search, and also for high-frequency band operation. The latency of cell search is expected to be significant compared to latency of other procedures to establish/ reestablish the connection (i.e., beam acquisition, MIB/SIB acquisition, random access procedure, beam refinement, and RRC connection (re-)establishment procedure). For standalone operation in aforementioned deployments, when the carrier frequency of the camp cell is unknown, finding the synchronization signal blocks (SSBs) may take minutes (before even performing any beam switching), since the UE scans for every frequency raster. The large bandwidth available in higher frequency bands exacerbates the problem, due to the increased number of carrier frequencies to be scanned. Given that no device is built optimized or even tested to operate in such limited-coverage scenarios and deployments, it is likely that a typical NR UE may not be even able to operate in such a situation due to the cell search/selection procedures.

[00100] For example, when UE goes out of the coverage of a cell, the UE tries to find other cell on different frequencies, and if the UE does not find any suitable cell, the UE keeps searching. This is because the current design of cell selection primarily supports looking for cells constantly until one is found to camp on. Depending on the number of frequencies on the frequency raster, the UE may end up searching even for hours. Even assuming that the UE starts with scanning the latest carrier frequency first, when the UE does not find any suitable cell during the transient in-coverage duration, the UE may be stuck in this stage and miss all in-coverage and link-availability opportunities. In sparse deployments, the reason that the UE may not find a suitable cell, may be that in a particular time that the UE is searching on a certain frequency (e.g., the latest carrier frequency, first), the UE may be out of the coverage island; by the time the UE is back to the coverage, the UE will no longer search for that carrier frequency and miss the (likely only) cell to select. The time that takes the UE to return to searching the (right) frequency again can be very large, e.g., depending on the number of frequencies, etc., and the UE may lose the coverage by that time. Even if all cells (or coverage islands) in the sparse deployment are on the same carrier frequency, the UE is to be enabled to search for that frequency for proper amount of time and start and stop the search at the right times. Currently, there is no network configuration to indicate and enable the UE to do so. Cell search with stored information is not configurable by the network, and currently, the UE decides what information is stored. In current technologies, there is no indication by the network on the UE cell search and cell selection behavior with/without stored information. Thus, proper definition of how to manage the UE cell search and cell selection procedures, when to start and when to stop these procedures, UE behaviors, etc. is desired to enable operation in the sparse deployments.

[00101] On the other hand, even though the UE behavior and implementation of cell selection is not specified, the 3GPP specification specifies the triggers, and cell selection procedure for initial cell access and connection establishment, as well as for connection reestablishment. In 3GPP systems, RRC signaling manages control signaling between UEs and the network, including (re-establishing and releasing connections. Going out of the network’s coverage area (e.g., in deployments with non-ubiquitous coverage), as well as facing link blockages inside the network coverage area, amongst other reasons such as handover failures, can make the RRC_CONNECTED UE undergo physical RLF. This currently triggers the RRC re-establishment procedure, which, if failed, ends up transitioning the UE into the RRC_IDLE state. Cell selection is performed on transition from the CM-IDLE to CM- CONNECTED state (e.g., for initial cell access), and when leaving connected mode, e.g., on transition from the CM-CONNECTED to CM-IDLE state (related to performing RRC reestablishment, e.g., if it is failed; the UE is not in the CM- IDLE state while performing RRC re-establishment). More accurately, the cell selection is not directly related to the transitions. For example, once the UE is camped normally, the UE may transition from the CM-IDLE to CM- CONNECTED state without cell selection. However, upon taking a particular set of actions, including cell selection, the UE may go through the state transition.

[00102] Particularly, both initial connection establishment and connection re-establishment procedures involve the cell search and cell selection procedure. As such, proper definition of the cell selection procedure, its requirements, and its triggers is desirable in order to enable operation in the desired and described deployments. In general, for future technologies, it is also possible to define a common framework for the initial access and/or mobility and/or link problem handling, with configurable procedures/parameters/timers tuned for different scenarios.

[00103] In one embodiment, in sparse deployments of interest with sporadic coverage, e.g., with only coverage islands/hotspots available, when the UE enters any of the coverage cells/islands within the deployment for the first time, the network indicates that the UE is to store and use information on the cell(s) to be selected. This information may include the carrier frequency (to avoid frequency raster scan) and (potentially all) essential cell and system information. This information may be used by the UE for the next time(s) that the UE (re-)enters the coverage, or upon facing and recovering from RLF. Such an indication from the network can be broadcasted or unicasted, e.g., based on the type of information to be stored, UE category, particular deployment, etc. The less information available at the UE at the time of entering the coverage, the more overhead and delay is expected to select and camp on the cell.

[00104] Directing the UE cell search and cell selection procedure can be, to some extent, similar to the RRC connection release procedure used to redirect a UE to another frequency or perform cell selection by leveraging stored information to speed up the procedure. However, the extent of the information to be stored to direct the cell selection procedure in the current scenarios of interest is likely broader compared to any existing cell-selection aiding/directing mechanism. To some extent, this is more towards reducing the time taken for cell selection by optimizing cell selection process (or the sub-procedures of cell selection), and also if possible for some cases, evading the core of the cell selection procedure and transitioning into a more cell selection-less operation. As the primary function of cell selection is to ensure that the cell the UE is going to use is suitable, possibilities and scenarios where the UE can assume suitability of a cell should also be considered. In addition, such knowledge-based operation may not be optional and/or be left up to UE implementation in the scenarios of interest. Particularly, the embodiments herein enable the functionality/operation in sparse deployments with limited coverage.

[00105] With the embodiments described herein, although for the first time that the UE enters the coverage of the sparse deployment, the cell selection may take longer than the subsequent instances, it may still be possible to expedite the first cell selection procedure. For example, assuming the UE is already registered to the network, some prior knowledge may be also defined and considered to help with first time access as well, e.g., even the initial MIB acquisition may be performed faster.

[00106] Considerations with respect to SIB1 acquisition

[00107] In NR, for a UE to initially access/acquire a cell, e.g., when entering the coverage (from the RRC_IDLE state), the UE acquires information on the MIB and SIB1. Once camped on the cell, rest of the SIBs are also acquired, and cell-reselection process starts to find any better cell. For the scenarios where the UE is to access the cell as fast as possible, the cell initial access can proceed with SIB1 acquisition (to ensure that the cell is acceptable/suitable and also make the random access configuration available to the UE). The beams used to obtain information from SSBs can also be used for SIB1 acquisition and retraining of beams for SIB1 decoding may be avoided.

[00108] In one embodiment, after the first time the UE enters a coverage island/cell, when the UE goes out of the coverage and re-enter the coverage, the UE relies on the previously acquired system information, including SIB1. In an extended example, a certain time period may be defined and if the UE has not been out of the coverage longer than the period, the UE can rely on the previously acquired system information, including SIB1. In another example, for certain deployments and scenarios, even for the time the UE enters the cell’s coverage, the UE may rely on pre-defined essential system information and proceed with the rest of the operation on the cell.

[00109] In one embodiment, one or more value tag(s) may be introduced inside the MIB to provide essential information of SIB1 and to help bypassing SIB1 acquisition, at least in certain scenarios and deployments. This approach also depends on the available space in the MIB. Currently, a System Information Value Tag is included within SIB 1 to provide an indication of whether or not the content of SIB 2 to SIB 9 or SIB 13 has changed and is to be re-acquired. The value tag is currently not applicable to the MIB, SIB 1, SIB 10, SIB 11 nor SIB 12. Particularly, UEs can use the System Info Value Tag to verify if the previously stored (other) system information messages are still valid or if a change has occurred in the system information messages.

[00110] In one example, the UE uses information about any previous cell(s) in the deployment that the UE had camped on before to facilitate cell selection and/or even MIB/SIB acquisition. For example, by entering the coverage and trying to access the cell, the UE may assume that the UE is in one of the cells previously accessed (e.g., by acquiring MIB, UE knows and checks the Physical Cell ID (PCI)). In this embodiment, the UE does not acquire the SIB (at least if value tag has not changed). The modification period may be set to be the shortest duration where modification is allowed, and the SIB may remain the same for a number of modification periods. The UE can check the value tag to see if the SIB has changed. Thus, the value tag may be applied in herein to, for example, SIB1.

[00111] In a more extreme case, even the MIB and PCI information may be reused from previous times, or such information may be pre-configured. In one example, the UE may rely on the acquired system information from a previous cell or previous times that UE has been in that cell, or from pre- configuration, i.e., default values always being pre-configured to the UE. Such pre-configuration is not available in NR.

[00112] In one extended example, certain coverage areas/islands of the deployment or the whole (private) deployment may be identified as a cell group over which, the UE may assume certain essential system information without critical changes. As such, even when going in and out of coverage and/or facing blockages, the UE may avoid re-acquiring information, re-selecting the cells, and/or performing conventional re-establishment procedures. For example, the deployment may contain one cell or multiple distant cells, either with potentially uniform coverage within each cell or spotty coverage even within the cell(s), such that the deployment area is not fully covered. The whole deployment may uniformly assume and rely on certain essential system information.

[00113] Example networks and scenarios and corresponding triggers of cell selection procedures [00114] In the scenarios of interest in opportunistic access, it is assumed that the UE had already performed a PLMN selection before the UE lost coverage. As such, the UE first attempts cell selection based on the same frequencies stored before coverage was lost. If that is not successful, the UE goes through an initial cell selection, and during that process, it is unlikely (in scenarios of interest) that the UE finds itself in a different PLMN to re-perform a PLMN selection. For the latter, exceptional, cases, cell access may take an extended amount of time. However, in the scenarios of interest, more common cases are considered, in which registration is not required upon coming back from out of coverage (re-entering coverage). If PLMN selection with registration is to be performed, the PLMN selection and registration process may take several sections depending on where the UE starts. However, this amount of time may be significantly curtailed if the UE is registering in the same PLMN and does not fetch the authentication vector.

[00115] Further, for each type of network, e.g., private networks, public- private networks, wideband networks, high frequency networks, etc., an independent solution may be used to enable the operation. FIG. 6 illustrates public/private network scenarios in accordance with some aspects. In particular, examples of private network use only and a combination of public and private network use is shown in FIG. 6. For example, each of the scenarios a and b depicted in FIG. 6 may use a different solution. As such, different scenarios and corresponding embodiments may be classified. Any difference(s) in terms of the procedures for initial access and/or reestablishment in each of the scenarios should be identified, and the embodiments should address corresponding roadblocks.

[00116] For example, in scenario a1/a2, the UE is out of coverage when outside of the private clouds in FIG. 6. During this time, the UE continuously searches for a cell; how frequently the UE searches is left up to the UE implementation (e.g., depending on the batteiy and many other factors). In scenario b1/b2, when the UE is in the PLMN (assuming that the UE is in PLMN coverage and allowed to access the PLMN, and PLMN has a proper deployment without huge coverage hole), when the UE comes (back) into the private network coverage (the small cloud), the UE may still be under the PLMN coverage, e.g., overlapping between the PLMN coverage and SNPN coverage (scenario b2). As such, the UE does not immediately look for the private network cell. Consequently, another mechanism may be used to trigger the UE to look for and access the private cell. In one embodiment, prioritization may be defined to help the UE find the private network since otherwise, once a UE is in a cell in which the UE receives the service, the UE will stay in that cell and will not look for another cell, another private network, another carrier, etc., unless there is a different trigger. In one example, if a UE enters a factory setting (e.g., scenario b1/b2) with available uplink or downlink data that can (e.g., only) be exchanged through the private network (assuming that the PDU sessions are established and in place), the search for and accessing the private network is initiated (data-based triggering).

[00117] If there is no overlap between PLMN coverage and SNPN coverage, then the UE goes out of coverage of the PLMN while entering the SNPN area, e.g., the SNPN covers the PLMN’s non-covered areas.

Accordingly, the trigger for the UE to look for a (private) cell, may not be taken care of separately, i.e., the trigger may happen more naturally as a result of going out of (PLMN) coverage.

[00118] In NR, the behavior has been left up to UE implementation and details are not specified. In LTE, proximity indication is defined as an UL message from the UE. The trigger for the UE to search for home cells is based on location information stored in the UE - either GPS or an RF fingerprint, which triggers the proximity indication to the network. The network uses this to initiate measurements of the home cell with the intention of performing handover to the home cell. Accordingly, the UE can remember the proximity in which the UE had found a private/home network with the previous RF conditions. It is left up to UE implementation whether the UE uses actual geographical coordinates, or only uses the RF map to remember the previous detection. Consequently, when similar conditions are triggered, the UE starts searching for the private network. However, as NR does not have such notions of home cells (there are only private networks in NR), the behavior is left up to the UE implementation, e.g., how the UE finds the private network, etc. [00119] In one example, a UE uses information of coverage map(s) built, updated, and maintained by potentially different networks (and the corresponding UEs) to manage its procedures and triggers (and even the state transitions) when the UE (potentially frequently) goes out of the coverage of a (private or public) network and comes back into the coverage of same or different network. For example, somewhat similar to the proximity umbrella concept in LTE, if a UE in an RRC_IDLE mode of a network knows that in a certain proximity the UE had previously been in a (same or different) network coverage (i.e., the UE knows the location either in terms of the RF map or the GPS geographical coordinates), then the UE can trigger looking for/identify the corresponding cell and camp on the corresponding cell. Particularly, the UE has access to the map so that when the UE enters geographical coordinates of a cell, the UE identifies the cell to camp on (when camped on a (suitable) cell, the UE performs the requirements for the RRC_IDLE state camped on any cell state, such as monitoring for PWS and emergency call).

[00120] In addition, if the network and the UEs together build a coverage map and exchange updated map information amongst themselves, the longer the map generation and update process is run, the more accurate the maps gets and a UE that has been operating in the system, obtains better understanding of the coverage holes/islands and is able to better manage UE procedures, transitions, and the state transitions. This is described in more detail in PCT application PCT/US2021/063383 and U.S. Provisional Patent App. No. 63/133,956, both entitled “TECHNIQUES TO IDENTIFY CAUSE OF LINK PROBLEMS, IDENTIFY BLOCKAGES, AND BUILD AND UPDATE BLOCKAGE MAP” and respectively filed December 14, 2021 and January 5, 2021, each of which is incorporated by reference in its entirety.

[00121] Overall, the disclosed embodiments may be indicated as the expected operation in certain deployments, e.g., where the network may configure specific operations/procedures, or can be applied or triggered based on knowledge of a map (coverage and/or blockage map), as well as knowledge of the location. As the disclosed embodiments equip the UE with (prior) knowledge on a cell existence and that the UE can already determine that the cell is a suitable cell, and the UE can have essential system information from a previous connection and/or pre-configuration, the cell selection process and/or the sub-procedures of cell selection can be optimized for the deployments of interest.

[00122] The current design of cell selection primarily supports looking for cells constantly until one is found to camp on. This is inspired by the current system design principle that coverage should always be available everywhere and the UE should always be anchored on a cell. However, it is not practical or feasible for the UE to keep searching for SSBs in deployments with sporadic coverage. One of the bottlenecks and infeasibilities discussed in section 5.1.2, the efficiency of running communications for high bands is also quite challenging (power amplification (PA), wider bandwidth, etc.), and the power consumption is high. The embodiment herein enable proper management of when the UE starts and/or stops the cell search procedure and enables the UE to find and select the right cell (which may be the only available cell) at the right time.

[00123] Under scenario b1/b2, in one scenario the UE in the RRC_INACTIVE state in the PLMN subsequently enters the coverage area of the private network. First, the UE is to find the private network cell and then camp on that cell. All these actions can still be taken while in the RRC_INACTIVE state. Still, as mentioned above, a trigger of the cell search function is used for the UE to find the private cell . While such a trigger may be based on data availability, other embodiments are possible. For example, the trigger can be based on RF conditions or location. For example, if the UE has GPS coordinates, the UE is able to determine that the UE is entering the coordinates where the UE knows there is a private network. Then, the UE can initiate the private network cell search. While the UE may, in addition, have continuously been searching for the private network, such a search is not efficient.

[00124] Once the UE has found the private network and can camp on the private network, whether the UE stays in the RRC_INACTIVE state (i.e., whether the UE performs an RNA or whether the UE performs RRC_IDLE state procedures to the connected transition), depends on whether the RNA is supported between these two boundaries (e.g., inter-PLMN RNA update and RRC_INACTIVE state transfer being possible). Currently, according to 3GPP TS 38.304, when a UE selects a new PLMN or SNPN, the UE transitions from the RRC_INACTIVE state to the RRC_IDLE state (excluding equivalent PLMNs (E-PLMNs)). In one embodiment, in order to support inter-PLMN RRC_INACTIVE state transfer, a unique identifier is defined to enable finding the old context, as well as an interface defined to retrieve the RRC_INACTIVE context from the PLMN base station to a private network base station.

Accordingly, the UE is then able to stay in the RRC_INACTIVE state and continue operation from this state.

[00125] Currently, the inactive RNTI (I-RNTI) is PLMN specific and cannot be used inter-PLMN, while the I-RNTI may be used across E-PLMNs, which requires coordination in I-RNTI allocation. It is possible to split the I- RNTI to include a PLMN component (similar to network sharing) such that inter-PLMN INACTIVE can also be supported.

[00126] In one example, when a UE enters a factory setting (e.g., scenario b1/b2), with some available uplink or downlink data that can (only) be exchanged through the private network, the UE is triggered to stay in the RRC_INACTIVE state. This may occur even when the UE exits the private network coverage, e.g., while being active in the PLMN.

[00127] Under scenario al/a2, in one scenario the UE in the RRC_INACTIVE state subsequently goes out of the coverage area of the private network. The current design transitions the UE into the RRC_IDLE state.

Particularly, the UE keeps searching for a suitable cell (any cell selection state), and after not finding any suitable cell to camp on, the UE finally ends up camped on any cell state (RRC_IDLE). As mentioned earlier, it is not possible to exactly quantify how long these transitions take (e.g., at what point the UE drops its context, at what point the UE enters the RRC_IDLE state once the UE is out of coverage, etc.). While the amount of time depends on how quickly the UE loses the cell, etc., about 10s may be a reasonable rough estimate of the incurred time. Once the UE is in any cell selection state, the UE has lost the cunent cell and has not found a suitable cell. The latency depends on how rapidly the UE loses the coverage of the cell and ends up in a state where the UE cannot find a suitable cell. This is not specified in 3GPP standards and depends on how rapidly the RF conditions change and the UE finds itself in that state.

[00128] As mentioned earlier, U.S. Provisional Patent App. No. 63/131,176 disclosed embodiments to keep the UE in the RRC_INACTIVE state, even if the UE goes out of the network coverage. Currently, when the UE has lost coverage and is in camped on any cell state (RRC_IDLE state), the UE may keep/start looking for cells based on mobility or any other triggers. The UE may find a suitable cell, and camp on the suitable cell while still in the RRC_IDLE state. While the current specification requires the UE to transition to the RRC_IDLE state, it is possible to keep the UE in the RRC_INACTIVE state for future technologies, as above. By preserving the RRC_INACTIVE state, the UE context is stored such that the context can be reused when the UE comes back into the coverage. When the UE transitions into the RRC_IDLE state, the UE releases the stored UE context. In some embodiments, an infinity timer may be used for a determination whether to delete the stored UE context; the network and the UE are synchronized such that the network will also store the UE context indefinitely. In this case, the UE is able to go out of the network coverage, keep storing the UE context, and reuse the previous stored context whenever the UE comes back into the coverage. By preserving the RRC_INACTIVE state when the UE goes out of the coverage, the UE may avoid performing all the (conventional) actions/procedures when in the RRC_INACTIVE state, e.g., cell reselection, paging monitoring, measurement and checking the criteria, etc. When the UE is out of the coverage, the UE only stores the context. Accordingly, when the UE is in any cell selection state (i.e., out of coverage) and in the RRC_INACTIVE state, when the UE finds a suitable cell, the UE remains in the RRC_INACTIVE state, and continue operation from there. This may be defined as a new extension of the UE states, which lies between any cell selection state and the RRC INACTIVE state. As shown in FIG. 5, in NR, UEs in either the RRC_IDLE state or the RRC_INACTIVE state can be in any cell selection state, while only UEs in the RRC_IDLE state are able to camp on a suitable cell if found after the search. This means that when such a cell is found, inactive UEs may enter idle and then camp on the cell. Otherwise, an inactive UE may continue in any cell selection state searching for a suitable cell.

[00129] Considerations with respect to re-accessing connection/cell (RRC connection re-establishment, etc.)

[00130] FIG. 7 illustrates RLF actions in accordance with some aspects. The RRC connection re-establishment procedure in NR and prior technologies permits re-establishment of the RRC connection (see, e.g., TS 38.331). A UE in the RRC_CONNECTED state, for which AS security has been activated with SRB2 and at least one data radio bearer (DRB) setup, may initiate the procedure to continue the RRC connection, e.g., upon facing an RLF, which may be due to a relatively long term link blockage or by going out of the coverage.

Particularly, upon declaring RLF, the UE tries to find a suitable cell; if found, the UE initiates connection re-establishment procedure as shown in FIG. 7. The connection re-establishment succeeds if the network is able to find and verify a valid UE context or, if the UE context cannot be retrieved and the network responds with an RRCSetup message according to clause 5.3.3.4 (fallback to RRC establishment).

[00131] The network applies the procedure as follows: when AS security has been activated and the network retrieves or verifies the UE context: re- activate AS security without changing algorithms and re-establish and resume the SRB1; when UE is re-establishing an RRC connection and the network is not able to retrieve or verify the UE context: discard the stored AS Context and release all RBs and fallback to establish a new RRC connection.

[00132] If AS security has not been activated, or if AS security has been activated but SRB2 and at least one DRB are not setup, the UE does not initiate the procedure but instead moves directly to the RRC_IDLE state with a release cause 'other' or 'RRC connection failure', respectively.

[00133] Currently, the UE performs cell selection when going to the IDLE state from the connected state (the box “cell selection up on leaving connected state” in FIG. 5), which normally may not involve any latency, as the current cell in which the UE was connected satisfies the suitability requirement in almost all cases and the UE simply camps on the same cell. Further, the cell selection procedure is used in such situation instead of cell reselection procedure to speed up the procedure. Cell selection in these cases is faster than cell reselection as the UE finds only a suitable cell (which is relatively fast as the UE already has measurements of the current cell), while during reselection the UE also measures neighboring cells to find the “best” cell to camp on.

[00134] As discussed above, by enabling the UE to stay in the RRC_INACTIVE state (or more accurately, a state between the UE being camped on any cell state and the RRC_INACTIVE state) with stored UE context even when the UE goes out of the cell coverage, upon coming back to the coverage of the same or different cell and/or network the AS security can then be immediately re-activated without changing algorithms and SRB1 can be resumed. In one embodiment, with certain knowledge-based triggering of cell selection and camping, the cell selection procedure can be performed only under limited circumstances and in a directed way. The knowledge may include coverage/cell existence by proximity detection based on location and/or RF conditions, coverage map, blockage map, etc. This may permit the cell selection procedure to be performed quickly, especially combined with cell selection based on stored knowledge of carrier frequency and/or cell/system information as above, for example, eliminating a significant amount of hypothesis testing and other uncertainties to be figured out by the UE.

[00135] In other words, both the triggering of cell selection, as well as the process of cell selection itself, can be directed based on certain information/ knowledge by (and/or between) the UE and network. Consequently, the process of recovery from RLF and/or losing and gaining coverage can be handled quickly and seamlessly, with minimized overhead. The more knowledge and/or higher level of system prediction, the faster any transition and/or procedure can take place, incurring less latency before the UE is able to use any available link/coverage. In TS 38.331, a set of actions following cell selection while RLF has been declared (i.e., T311 timer is running) has been specified. Particularly, upon selecting a suitable NR cell, the UE ensures having valid and up to date essential system information, applies the default L1 parameter values as specified in corresponding physical layer specifications except for the parameters for which values are provided in SIB1, and initiates transmission of the RRCReestablishmentRequest message. This procedure applies also if the UE returns to the source PCell.

[00136] In one example, by providing/enabling the relevance knowledge as discussed above, e.g., on the cell to be selected, the corresponding system information, etc., the reestablishment request may be immediately sent, and the operation can be quickly continued/started. In one example, even the RRCReestablishmentRequest message may not be transmitted in certain conditions. These conditions include when network also has enough level of knowledge and prediction about the UE’s situation. In order for the UE to start the initial access in a new cell, the UE should identify itself in the new cell. For example, the UE may identify itself in a cell based on location information, coverage map, etc. In another example, the UE may be provided with a dedicated random access channel (RACK). While in current systems this option may not be feasible due to level of RACK resources to be reserved, but in future system design, this may be addressed. Examples of re-accessing the same cell are discussed below.

[00137] In order to handle link problems in the current technology design, some counters and timers are considered to track in-sync and out-of-sync events. If a certain number of consecutive in-sync indications are observed/received before expiration of T310 timer, also called RLF declaration timer, the UE returns to normal operation. If T310 timer expires without the UE observing enough in-sync indications, the UE considers itself in a RLF condition. As specified in TS 38.331 subclause 5.3.10.3, RLF detection may be due to T310 timer expiry, which may happen due to blockages and/or coverage limitations. [00138] After RLF declaration, the UE initiates the steps for connection reestablishment. This includes performing cell selection to identify a cell to perform reestablishment. Each UE, upon detecting an RLF, starts a timer which expires after a predetermined configured time period (RLF timer duration) as part of a reestablishment procedure. In NR and prior technologies, this timer is called T311 timer, and ends once the UE finds a suitable cell for RRC connection reestablishment or expires after a predetermined time period. If the UE identifies and selects a suitable cell for reestablishment within the T311 time period, the UE transmits an RRC reestablishment request message. In TS 38.331, the UE actions upon RLF T311 timer expiry have also been specified. Particularly, if the procedure was initiated due to RLF or handover failure, the noSuitableCellFound in the VarRLF-Report is set to true, and the UE performs actions upon entering the RRC_IDLE state, with release cause 'RRC connection failure'. Similarly, if the selected cell becomes no longer suitable according to cell selection criteria specified in TS 38.304, the UE performs actions upon going to the RRC_IDLE state, with release cause 'RRC connection failure'. [00139] The reestablishment procedure allows the UE to access another cell if the UE has any problem with its current serving cell. Without the reestablishment procedure, there is no other AS procedure that the UE is able to use. As such, the UE falls back to the NAS procedure. Accordingly, the possibility/feasibility of completely bypassing the functionality of the reestablishment in certain deployments, scenarios, or use-cases, should be carefully thought through. At the same time, it is possible to design the timers, and triggers in a more appropriate manner for the scenarios of interest.

[00140] In particular, by defining the RRC_INACTIVE state as the fallback state, even when the UE goes out of cell/network coverage, the timer design and the corresponding actions are also revisited. In one example, in certain deployments, the RLF timer (T311 timer) may not be triggered/used or may be set to a sufficiently large value (or to infinity) to avoid transitioning to the RRC_IDLE state before likely reentry to coverage in the particular area of sparse deployment (e.g., the value may increase as the coverage island size decreases/size between islands increase). Thus, for example, the T311 timer is proportional to the distance between islands. In another example, with proper enabling of the UE to perform knowledge-based cell selection, expiry of the T311 timer before finding a suitable cell is avoided. In yet another example, upon expiry of a T311-like timer, the UE transitions to the RRC_INACTIVE state, while the UE context is stored.

[00141] In one example, the UE does not wait until the T310 timer expires to initiate a Connection Reestablishment procedure (or a shortened procedure that is faster and less involved than the current reestablishment procedure), if the UE has knowledge of availability/unavailability of another cell coverage or the same cell coverage. The use of the T310 timer allows the UE to avoid ending up looking for another cell when the UE can potentially recover faster in the same cell. For example, if the UE knows that the current link problem is due to a blockage and/or that based on the UE mobility/speed, another coverage island/cell is/is not available in the UE vicinity, the UE can accordingly adjust the UE behavior and triggering of any procedure such as reestablishment and cell search/selection. Particularly, if the UE knows that waiting for the current timer (for that period) is not appropriate for a particular scenario, the UE can perform more optimized actions, e.g., using a shorter timer or bypassing some of the steps/procedures.

[00142] For example, if other cells are available in the small cell scenarios of interest, forcing the UE to continue in the same cell for the T310 timer may not be the best approach and some optimizations of reestablishment procedure can be enabled. As such, more frequent occurrences of the reestablishment procedure may be allowed. On the other hand, for sparse deployments where no other cell may be immediately available, it may be beneficial to take other actions, wait longer before declaring RLF and initiating the reestablishment procedure, or avoid some of the involved steps/procedures.

[00143] In one embodiment, based on prior knowledge, e.g., location, map, etc., in response to a determination that the UE is in the same cell, the UE can avoid the reestablishment procedure (upon facing RLF) and only perform a random access procedure to re-access the cell (similar to beam failure recovery). In such an example, the system information does not change before and after the RLF, and the reestablishment (if any) for the same cell can be much quicker than reestablishment to a different cell. In one example, with sufficient knowledge (of location, map, etc.) at both the UE and the network side, and when both sides can be ensured to be in-sync with each other to re-access the network, the UE may avoid performing the random access procedure.

[00144] In the sparse deployments with sporadic coverage and in high frequency band operation, it is not ideal for the UE to perform cell search and cell selection every time the UE goes in and out of the coverage or faces a link blockage. In particular, for the case of blockage, the UE may be better off staying in the same cell and attempt recovery in the same cell. In one example, in certain deployments and scenarios, the UE may be redirected to the desired cell (e.g., same cell) after facing an RLF. The redirection may be based on prior information of the deployment, location, etc., or based on network configuration upon the first time the UE has entered the coverage, etc.

[00145] As above, more generally, certain coverage areas/islands of the deployment or the whole (private) deployment may be identified as a (cell) group over which the UE may assume certain essential system information without critical changes. As such, even when going in and out of coverage and/or facing blockages, the UE may avoid re-acquiring information, re- selecting the cell(s), and/or performing conventional re-establishment procedures.

[00146] Currently, when random access procedure failure occurs, the UE may not stay in the cell. The UE may try finding a suitable cell and attempting the random access procedure in another cell. There may be ways to restrict when random access failure triggers RLF and cell selection. For example, if the UE has already found other candidate beams, e.g., backup beams, the UE may continue the random access procedure using those beams. In another example, the UE may re-perform the random access procedure using the previous/original selected beams after waiting a predetermined amount of time. This time may depend on characteristics of the link problem, UE speed, location e.g., the duration of blockage or coverage problem.

[00147] It is also possible to consider scenarios and/or UE implementations where the UE is able to realize/identify the nature of the link problem, based on whether the UE has moved and/or its speed, and take actions accordingly. For example, if the UE realizes that no meaningful movement has been made, the UE waits until the (mobile) blockage is cleared and assumes that the UE is (most likely) in the same cell. In this case, meaningful movement may be movement that could result in a link problem. This behavior would be beneficial if there is no other alternative cell available. The UE may have identified the unavailability of other cells based on the measurements performed during connected mode operation. The UE may check whether its serving cell before the blockage is still suitable, which may be done quickly. If the UE finds the serving cell remains suitable, the UE may avoid reading the SIB, etc., and can immediately access the cell. In another example, instead of checking whether the serving cell is still suitable before the out-of-coverage event or before blockage, the UE can assume the serving cell is suitable. As above, this may be assumed by the UE if the UE has not moved, etc. (also relevant to the statistic and nature of blockage). In other words, in sparse deployments, a suitable cell can be assumed to be the most recent cell on which the UE was operating. In such case, the functionality of the T311 timer is evaded, as the suitable cell is immediately identified, and use of the T311 timer may be avoided.

[00148] Opportunistic access

[00149] One focus of opportunistic access is on the standalone high- frequency band deployment scenarios with limited and sparse coverage. Different scenarios are listed in Table 1, followed by their corresponding impacts on the procedures to access the cell/network (e.g., potential difference in cell selection and/or required acquisition steps), as well as coverage range (UE in-coverage duration) in Table 2.

Table 1

[00150] One distinction between patchy coverage and case 1 is that the OOC duration may be comparable or of the same order as the in-coverage duration. If the UE does not go OOC for an extended period, the UE may not lose all aspects of the previous serving cell (which is also the current cell). Particularly, the UE may be assumed to be in the same cell (and is able to determine this just by acquiring the MIB, as the PCI has not changed). The UE may avoid acquiring the SIB (at least if modification period has not changed). As such, some of the access delays may not be applicable.

Table 2

[00151] FIG. 8 illustrates a 5G NR initial access procedure in accordance with some aspects. FIG. 8 entails different sub-procedures to acquire cell access. In FIG. 8, a synchronization raster scan is used that currently outweighs the latency of the remaining initial access operations. Thus, as above, by having a knowledge-led cell search/identification/selection, e.g., raster scan may be avoided or decreased. The UE identifies the strongest cell as per the CD-SSB located on the synchronization raster and proceed to decode the system information. If the UE discovers a set of SSBs without any associated system information, the UE moves to another set of SSBs as cells without SIB1 cannot be used as a PCell.

[00152] Cell selection given the carrier frequency and initial beam acquisition without the burden of the raster scan also occurs in FIG. 8. The latency of beam acquisition outweighs the remaining initial access operations. The cell detection and selection can be faster by relying on information provided by the network, or from previous occasions that the UE accessed the cell, and from location and map knowledge. Finding the beam to establish the connection with the identified cell remains a challenge in terms of latency, including finding the PSS/SSS, taking measurements, and decoding the MIB. The UE may continue with measurements of cells in parallel and pick the strongest/suitable PSS/SSS as initial beam acquisition is performed as part of finding a suitable cell.

[00153] To find an acceptable (not necessarily the strongest) cell, although not specified, the UE compares RSRP across different Rx beams and chooses the highest. By doing so, the UE selects best Rx beam. To find the strongest cell, the UE completes measurements of all neighboring cells and compares the signal strength and quality of all the cells. If the UE is to obtain immediate access after coming back into coverage, the UE is allowed to do cell selection and make access on a cell that is acceptable (i.e., as long as it can do measurements for one cell and it is acceptable, the cell may not be the strongest cell). In limited coverage scenario, the likelihood of availability of neighboring cell(s) is low and the UE may measure the only available cell.

[00154] The UE proceeds with SIB1 acquisition, and then the CP procedure (RACK and RRC connection establishment) shown in FIG. 8.

[00155] The latency of initial access procedure heavily depends on SNR assumptions. What SNR regime to assume in the analysis depends on the scenario of interest. While the worst-case SNR (i.e., cell edge) is not assumed in all the cases in Table 3, when the UE enters the cell’s coverage area from the cell edge, for the initial access, cell-edge SNR condition is to be considered. As such, a reasonable SNR assumption is to be used for analyzing initial access latency when the UE enters a cell coverage. In the numerical analysis below, the calculation assumes different numbers depending on the coverage range assumed for a given case compared to the maximum cell coverage radius.

Table 3

[00156] : Each step of the high-band access and connection establishment procedure is subject to blockage occurrence which can significantly increase the corresponding latency, although the exact characterization of blockage depends on many untraceable factors. Further, the higher initial access latency (the longer procedures), the more likely blockage happens during the access procedures. This implies a two-fold negative impact from blockage.

[00157] The UE may not constantly perform scanning for cell search/sel ection to save UE power. As such, additional latency may be added. [00158] Further, cell selection itself, can require a significant time due to sync frequency raster scan, and is likely the bottleneck of UE’s operation under limited coverage. Also, an NR UE in limited coverage deployments may get stuck at the cell search/sel ection step and operation may be infeasible, e.g., by missing the target cell frequency due to OOC/blockage and not coming back to that frequency shortly enough, etc. [00159] If PLMN selection with registration is also used, depending on where the UE starts, this selection may add several seconds to the access latency. However, if the UE is registering in the same PLMN and does not fetch the authentication vector, the selection may take shorter.

[00160] Analysis of opportunistic access cases

[00161] For the current analysis, for data transmission under limited coverage (e.g., sparse deployment with coverage islands), the following aspects are considered:

[00162] 1) Depending on the deployment scenario (carrier frequency, antenna array setting, beam-width, etc.), the coverage range is estimated (via link-budget analysis) for a single cell. Consequently, an estimate of the average per UE coverage-time can be obtained based on the UE speed, cell load (#UEs), and overall overhead channels (SSB, CSI-RS, DMRS, SRS, PTRS), beam tracking, etc. For NLOS in 100GHz, cell diameter may be about 94m, resulting in a max of 30s (6s) in coverage duration for 3m/s (60km/h) mobility, and assuming simple linear UE trajectory. For NLOS in 100GHz, cell diameter may be about 66m, resulting in a max of 20s (3.7s) in coverage duration for 3m/s (60km/h) mobility, and assuming simple linear UE trajectory. 28 GHz pathloss is ~12dB lower than 100 GHz, requiring 12dB more antenna gains for same coverage. The 64x64 antennas provides 6dB gain at each Rx and Tx compared to 16x16 antennas. On the other hand, the antenna size is reverse proportional to carrier frequency. Comparing carrier frequencies of 100 and 28 GHz, about 4 times reduction in antenna size, and inter-antenna distance is expected.

Particularly, with the same antenna area in device, more number of antennas at higher frequency band is possible, i.e., if the current assumption for 28GHz is 16x16 antennas, then 64x64 antennas for 100GHz is reasonable. For cases with fixed BS beam and no tracking such as Case #4 in Table 6-1 (e.g., BS at street- lamp port with no tracking of UE’s mobility, etc.), the coverage may be estimated as 2*(link-budget coverage)*sin (HPBW/2), where θ=HPBW/2~pi/(#Tx antenna elements). However, to benefit from this coverage range, the Tx antenna should be installed at a very high height (very directional). At ~10-15m street lam height, the area coverage area becomes smaller with the same θ angle, with more concentrated power. This can achieve higher supported throughput in a more limited area.

[00163] 2) The expected access latency (once UE enters the coverage) and its contributing components have been analyzed and assessed below.

[00164] 3) The average time a UE spends in cell coverage should accommodate gaining access and transferring data. As such, the access latency compared to the average UE in-coverage time, gives insight on whether a reduced access delay is needed, e.g., for more nominal types of scenarios.

Assuming that the UEs in a cell, use full bandwidth and have same share of time (TDMed), the total available time resource for a UE’s data transfer can be roughly estimated as (in-coverage duration - access delay)x(1 - DL OH%)x(1 - UL OH%) _ #active UEs per cell (e.g.,at the time of data transfer phase for UE of interest) ^. (1)

Table 4 Assumptions and settings Table 5 Analysis of achievable coverage time and data transfer

[00165] The above analysis shows that for high-speed and some low- speed scenarios, performance beyond NR is required. Particularly, the NR performance (for SA high-band operation with limited coverage, and likely with no possible handover) is not acceptable or the operation is infeasible, i.e., the per-UE airtime according to Equation (1), results in a very small or even negative value. This observation holds true even without considering blockage impact which can be severe and cause service interruptions (the duration of which depends on the deployment scenario), and without including the latency due to potential cell reselection procedure.

[00166] Accordingly, enhancements targeting reduced access latency due to any of the procedures/steps of the initial access, including the cell selection, synchronization and beam acquisition, SIB acquisition, and CP procedure (RACK, RRC connection (re-)establishment/resume, etc.), may enable operation in certain deployment scenarios. Further, the time duration within THz coverage in non-blocked state is transient and valuable. As such, even small amount of latency reduction can translate into a significant amount of additional data transfer due to the high throughput. In general, the evolvements of access procedure may target reducing how frequent the corresponding procedure is required, as well as how long each round of performing the procedure may take. [00167] Considering the likelihood of blockage in higher band operation, on top of the incorporated access latencies, the UE may spend a significant amount of time in the blocked state, and infeasibility problem may be even more severe (e.g., may need to subtract the total (significant) amount of time UE spends in the blocked state as well as the latency of blockage recovery procedures, from in-coverage duration). Accordingly, proper handling/accel erating of both access procedure as well as link issues and blockages for standalone high-band operation with sparse coverage described herein may be used.

[00168] Examples of the above embodiments include:

[00169] Example 1 is an apparatus for a user equipment (UE), the apparatus comprising: processing circuitry configured to: determine that the UE has entered a coverage area within an area of sparse deployment of cells; determine whether the UE has stored cell information of a cell in the coverage area, the cell information comprising carrier frequency and system information broadcast 1 (SIB 1 ); and in response to a determination that the UE has previously entered the coverage area, use the cell information to establish communications with the cell; and a memory configured to store the cell information.

[00170] In Example 2, the subject matter of Example 1 further includes that the processing circuitry is further configured to: decode a master information block (MIB) comprising a Physical Cell identifier (PCI) and a value tag, the value tag including information of the SIB1 of a cell in the coverage area; determine whether the UE has previously entered the coverage area based on the cell information and the PCI; and in response to a determination that the UE has previously entered the coverage area, determine whether to bypass acquisition of the SIB1, determination of whether to bypass acquisition of the SIB1 based on at least one of: the value tag, or a modification period decoded from the cell or predetermined that defines a time period over which system information modification is allowed.

[00171] In Example 3, the subject matter of Example 2 further includes that: the cell information comprises a previously obtained value tag, and the processing circuitry is configured to determine whether to bypass acquisition of the SIB1 based on whether the value tag is different from the previously obtained value tag.

[00172] In Example 4, the subject matter of Examples 2-3 further includes that: the time period is predefined or indicated in the MIB, and in response to a determination that the UE has not been out of coverage longer than the time period, the processing circuitry is configured to rely on previously acquired system information, including SIB1.

[00173] In Example 5, the subject matter of Examples 1-4 further includes that: the cell information comprises a master information block (MIB) comprising a Physical Cell identifier (PCI) of a cell in the coverage area, and the processing circuitry is further configured to use the MIB and the PCI of the cell information to bypass acquisition of the SIB1.

[00174] In Example 6, the subject matter of Examples 1-5 further includes that the processing circuitry is further configured to: perform public land mobile network (PLMN) selection to register with a PLMN after entry into the coverage area; determine that the UE has lost coverage provided by the coverage area after PLMN selection; upon reentering coverage, determine based on UE characteristics, that the coverage is still provided by the PLMN; and bypass authentication in response to a determination that the coverage is still provided by the PLMN.

[00175] In Example 7, the subject matter of Examples 1-6 further includes that the processing circuitry is further configured to: determine that the UE has lost coverage provided by the coverage area, the area of sparse deployment of cells being a private network, the UE remaining in an INACTIVE state with stored UE context after the coverage of the private network is lost; after a determination of lost coverage, obtain coverage from a public network, the coverage of the public network overlapping the coverage of the private network; and upon reentering coverage provided by the private network and the coverage from the public network remaining, access the private network and drop the coverage of the public network based on prioritization between the private network and the public network.

[00176] In Example 8, the subject matter of Examples 1-7 further includes that the processing circuitry is further configured to: determine that the UE has lost coverage provided by the coverage area, the area of sparse deployment of cells being a private network, the UE remaining in an INACTIVE state with stored UE context after the coverage of the private network is lost; after a determination of lost coverage, obtain coverage from a public network, the coverage of the public network overlapping the coverage of the private network; and upon reentering coverage provided by the private network and the coverage from the public network remaining, access the private network and drop the coverage of the public network based on an exchange of data with the private network, the data limited in availability to the private network.

[00177] In Example 9, the subject matter of Examples 1-8 further includes that the processing circuitry is further configured to: determine that the UE has lost coverage provided by the coverage area, the area of sparse deployment of cells being a private network, the UE remaining in an INACTIVE state with stored UE context after the coverage of the private network is lost; after a determination of lost coverage, obtain coverage from a public network, the coverage of the public network overlapping the coverage of the private network; and upon reentering coverage provided by the private network and the coverage from the public network remaining: determine reentry of coverage provided by the private network based on or more of: radio frequency (RF) conditions of private network stored in the memory, or geographical location and private network coverage map information; and in response to a determination of reentry of coverage provided by the private network, access the private network and drop the coverage of the public network.

[00178] In Example 10, the subject matter of Examples 1-9 further includes that the processing circuitry is configured to: determine that the UE has lost coverage provided by the cell; after a determination of lost coverage, determine whether the UE remains within the area of sparse deployment from a radio frequency (RF) or coverage map of the area of sparse deployment; and in response to a determination that the UE remains within the area of sparse deployment, identify, select, and camp on a corresponding cell based on the map or location knowledge.

[00179] In Example 11, the subject matter of Examples 1-10 further includes that the processing circuitry is configured to use a unique identifier to support an inter-public land mobile network (PLMN) INACTIVE state and enable finding a prior UE context, the identifier comprising a PLMN component that is specific to the PLMN.

[00180] In Example 12, the subject matter of Examples 1-11 further includes that in response to a determination that the UE is in the area of sparse deployment, the processing circuitry is configured to at least one of: initiate a Connection Reestablishment procedure prior to expiration of a radio link failure (RLF) T310 timer; or one of: avoid triggering a T311 timer or set the T311 timer to a value to avoid expiry of T311 timer before finding a suitable cell and remain in an INACTIVE state.

[00181] In Example 13, the subject matter of Examples 1-12 further includes that in response to a determination that the UE is in the area of sparse deployment and is in a same cell before and after radio link failure (RLF), the processing circuitry is configured to avoid a reestablishment procedure and limit procedures to re-access the cell to a random access procedure, determination that the UE is in the same cell before and after RLF based on at least one of knowledge of UE location, radio frequency (RF) conditions, or a coverage map. [00182] In Example 14, the subject matter of Examples 1-13 further includes that the cell information is acquired one of: from another cell in the area of sparse deployment with which the UE previously established communications, from a previous time that UE has established communication with the cell, or from pre-configured default values.

[00183] In Example 15, the subject matter of Examples 1-14 further includes that the processing circuitry is configured to use predetermined cell or system information within at least one of a portion of the area of sparse deployment without at least one of: re-acquisition of at least a portion of the system information, re-selection of cells within the area of sparse deployment, or performance of re-establishment procedures used outside the area of sparse deployment.

[00184] In Example 16, the subject matter of Examples 1-15 further includes that the processing circuitry is configured to determine an INACTIVE state with stored UE context is a fallback state, based on a determination that the UE is within the area of sparse deployment, and at least one of: the UE is out of coverage of a previously acquired primary cell or a T311 timer has expired.

[00185] Example 17 is an apparatus for a cell, the apparatus comprising: processing circuitry configured to: generate, based on information from user equipments (UEs) and other cells within an area of sparse deployment that contains the cell, a radio frequency (RF) map; encode, to a first UE, the RF map and an indication to store system information associated with the cell; and decode, from the first UE while the first UE is in at least one of an RRC_INACTIVE state or an RRC_IDLE state, communications based on the RF map; and a memory configured to store the RF map.

[00186] In Example 18, the subject matter of Example 17 further includes that the processing circuitry is configured to: encode, for transmission to the first UE, an indication of a radio link failure (RLF) T311 timer with a value that avoids transition of the first UE to the RRC_IDLE state, or decode, from the first UE, a Connection Reestablishment procedure prior to expiration of a radio link failure (RLF) T310 timer.

[00187] Example 19 is a non-transitory computer-readable storage medium that stores instructions for execution by one or more processors of a user equipment (UE), the one or more processors to configure the UE to, when the instructions are executed: determine that the UE has entered a coverage area within an area of sparse deployment of cells; determine whether the UE has stored cell information of a cell in the coverage area, the cell information comprising carrier frequency and system information broadcast 1 (SIB1); and in response to a determination that the UE has previously entered the coverage area, use the cell information to establish communications with the cell.

[00188] In Example 20, the subject matter of Example 19 further includes that the instructions, when executed, further configure the one or more processors to configure the UE to: determine that the UE has lost coverage provided by the cell; after a determination of lost coverage, determine whether the UE remains within the area of sparse deployment from a radio frequency (RF) map of the area of sparse deployment; and in response to a determination that the UE remains within the area of sparse deployment, identify and camp on a corresponding cell based on the RF map.

[00189] Example 21 is at least one machine-readable medium including instructions that, when executed by processing circuitry, cause the processing circuitry to perform operations to implement of any of Examples 1-20.

[00190] Example 22 is an apparatus comprising means to implement of any of Examples 1-20.

[00191] Example 23 is a system to implement of any of Examples 1-20. [00192] Example 24 is a method to implement of any of Examples 1-20. [00193] Although an embodiment has been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader scope of the present disclosure. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The accompanying drawings that form a part hereof show, by way of illustration, and not of limitation, specific embodiments in which the subject matter may be practiced. The embodiments illustrated are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. This Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled.

[00194] The subject matter may be referred to herein, individually and/or collectively, by the term “embodiment” merely for convenience and without intending to voluntarily limit the scope of this application to any single inventive concept if more than one is in fact disclosed. Thus, although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description. [00195] In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of "at least one" or "one or more." In this document, the term "or" is used to refer to a nonexclusive or, such that "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise indicated. In this document, the terms "including" and "in which" are used as the plain-English equivalents of the respective terms "comprising" and "wherein." Also, in the following claims, the terms "including" and "comprising" are open-ended, that is, a system, UE, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

[00196] The Abstract of the Disclosure is provided to comply with 37 C.F.R. § 1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.