Determination of Sidelink Connection Timers for Establishing Communication via Sidelink Relay

Abstract

Apparatus, methods, and systems for configuring sidelink connection timers are disclosed. One method (1300) includes receiving (1305) a set of connection timers from a first system information block transmission of a serving node and receiving (1310) a first set of sidelink connection timers from an additional system information block of the serving node. The method (1300) includes determining (1315) a second set of sidelink connection timers for establishment of communication with a network node using an UE-to-Network ("U2N") sidelink relay UE, where a respective value of each timer of the second set of sidelink connection timers is determined based at least in part on the first set of sidelink connection timers. The method (1300) includes using (1320) the respective connection timers to manage establishment of communication with the network node via the U2N sidelink relay UE.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 287,251, entitled “SIGNALING CONNECTION ESTABLISHMENT TIMERS TO A SIDELINK REMOTE UE,” filed on January 21, 2023, to Prateek Basu Mallick, Karthikeyan Ganesan, Joachim Lohr, and Ravi Kuchibhotla, which is incorporated herein by reference.

[0002] The subject matter disclosed herein relates generally to wireless communications, and more particularly, to configuring connection establishment timers for sidelink communications, e.g., for establishing communications between a remote user equipment ("UE") and a network node using a UE-to-Network ("U2N") sidelink relay. [Background technology]

[0003] In sidelink communications, a UE can communicate directly with another UE without relaying the UE's messages through a wireless network. In 3rd Generation Partnership Project ("3GPP"), sidelink communications may also be used to extend the coverage area of ​​a Radio Access Network ("RAN") by having signaling between out-of-coverage UEs and a serving network node (e.g., a RAN node) relayed to an in-coverage UE (i.e., via sidelink communications). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TR 38.836 [Non-Patent Document 2] 3GPP TS 38.331(v16.6.0) [Non-Patent Document 3] 3GPP TS 38.213, Section 13 [Non-Patent Document 4] 3GPP TS 36.331 Summary of the Invention [Means for solving the problem]

[0005] Disclosed are procedures related to configuring a connection establishment timer for sidelink communications, also referred to herein as a “sidelink connection timer,” that may be implemented by an apparatus, a system, a method, or a computer program product.

[0006] One method in a UE includes receiving a set of connection timers from a first system information block transmission of a serving node and receiving a first set of sidelink connection timers from an additional system information block of the serving node. The method includes determining a second set of sidelink connection timers for establishment of communication with a network node using a U2N sidelink relay UE, where a respective value of each timer of the second set of sidelink connection timers is determined based at least in part on the first set of sidelink connection timers. The method includes using the respective connection timers to manage the establishment of communication with the network node via the U2N sidelink relay UE.

[0007] A more particular description of the embodiments briefly described above will be made by reference to specific embodiments which are illustrated in the accompanying drawings, in which the embodiments will be described and explained with more specificity and detail, with the understanding that these drawings illustrate only some embodiments and therefore should not be considered limiting in scope, and in which: [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic block diagram illustrating an embodiment of a wireless communication system for configuring a sidelink connection timer. [Diagram 2] FIG. 1 is a block diagram illustrating one embodiment of a New Radio ("NR") protocol stack. [Diagram 3] A diagram illustrating one embodiment of a connection establishment procedure between an out-of-coverage UE and a serving network node via a U2N sidelink relay UE. [Figure 4] A diagram illustrating one embodiment of a connection re-establishment procedure between an out-of-coverage UE and a serving network node via a U2N sidelink relay UE. [Diagram 5] A diagram illustrating one embodiment of a connection resumption procedure between an out-of-coverage UE and a serving network node via a U2N sidelink relay UE. [Figure 6] A diagram showing one embodiment of a connection resumption procedure with network release or interruption between an out-of-coverage UE and a serving network node via a U2N sidelink relay UE. [Figure 7] FIG. 1 illustrates one embodiment of an information element (“IE”) containing a set of UE timers and constants. [Figure 8] FIG. 1 illustrates an embodiment of an IE containing a set of sidelink specific UE timers and constants. [Figure 8] FIG. 13 illustrates an embodiment of a sixth interlace scheme for sidelink operation. [Figure 9A] FIG. 1 illustrates one embodiment of a System Information Block #1 ("SIB1") that includes a set of UE timers and constants, as well as additional offset time for connection procedures via sidelink relays. [Figure 9B] This is a continuation of SIB1 shown in Figure 9A. [Figure 10] FIG. 1 is a block diagram illustrating one embodiment of a sidelink relay arrangement and associated connection timers. [Figure 11]FIG. 1 is a block diagram illustrating an embodiment of a user equipment device that may be used to configure a sidelink connection timer. [Figure 12] FIG. 1 is a block diagram illustrating an embodiment of a network device that may be used to configure a sidelink connection timer. [Figure 13] 1 is a flow diagram illustrating an embodiment of a first method for configuring a sidelink connection timer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] As will be appreciated by one skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Accordingly, the embodiments may take the form of an all-hardware embodiment, an all-software embodiment (including firmware, resident software, microcode, etc.) or an embodiment combining software and hardware aspects.

[0010] For example, the disclosed embodiments may be implemented as a hardware circuit comprising custom very large scale integrated ("VLSI") circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. The disclosed embodiments may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, etc. As another example, the disclosed embodiments may include one or more physical or logical blocks of executable code which may be organized as, for example, objects, procedures, or functions.

[0011] Furthermore, embodiments may take the form of a program product embodied in one or more computer readable storage devices storing machine readable code, hereinafter referred to as code, computer readable code, and / or program code. The storage devices may be tangible, non-transitory, and / or non-transmitting. The storage devices may not embody signals. In certain embodiments, the storage devices employ only signals to access the code.

[0012] Any combination of one or more computer readable media may be utilized. The computer readable medium may be a computer readable storage medium. The computer readable storage medium may be a storage device that stores the code. The storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micro-mechanical, or semiconductor system, apparatus, or device, or any suitable combination thereof.

[0013] More specific examples (non-exhaustive list) of storage devices include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory ("RAM"), a read-only memory ("ROM"), an erasable programmable read-only memory ("EPROM" or flash memory), a portable compact disk read-only memory ("CD-ROM"), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the context of this specification, a computer-readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0014] The code for carrying out the operations of the embodiments may be any number of lines and may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Python, Ruby, Java, Smalltalk, C++, ordinary procedural programming languages ​​such as the "C" programming language, and / or machine code such as assembly language. The code may run entirely on the user's computer, partially on the user's computer as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the last scenario, the remote computer may be connected to the user's computer via any type of network, including a local area network ("LAN"), wireless LAN ("WLAN"), or wide area network ("WAN"), or a connection to an external computer may be made (e.g., via the Internet using an Internet Service Provider ("ISP").

[0015] Furthermore, the described features, structures, or characteristics of the embodiments may be combined in any suitable manner. In the following description, numerous specific details, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., are provided to provide a thorough understanding of the embodiments. However, those skilled in the art will recognize that the embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the embodiments.

[0016] Reference throughout this specification to "one embodiment," "an embodiment," or similar language means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, throughout this specification, the appearance of the phrases "in one embodiment," "in an embodiment," and similar language may, but do not necessarily, all refer to the same embodiment and may mean "one or more, but not all, embodiments" unless otherwise specified. The terms "including," "comprising," "having," and variations thereof mean "including, but not limited to," unless otherwise specified. An enumerated list of items does not imply that any or all of the items are mutually exclusive, unless otherwise specified. Additionally, the terms "a," "an," and "the" refer to "one or more," unless otherwise specified.

[0017] As used herein, a list using the conjunction "and / or" includes any single item in the list or a combination of items in the list. For example, a list of A, B, and / or C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the term "one or more of" includes any single item in the list or a combination of items in the list. For example, one or more of A, B, and C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the term "one of" includes only one of any single item in the list. For example, "one of A, B, and C" includes only A, only B, or only C, and excludes the combination of A, B, and C. As used herein, "at least one of A, B, and C" includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, "a member selected from the group consisting of A, B, and C" includes only one of A, B, or C, and excludes the combination of A, B, and C. As used herein, "a member selected from the group consisting of A, B, and C and combinations thereof" includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C.

[0018] Aspects of the embodiments are described below with reference to schematic flow charts and / or schematic block diagrams of methods, apparatus, systems, and program products according to the embodiments. It will be understood that each block of the schematic flow charts and / or schematic block diagrams, and combinations of blocks in the schematic flow charts and / or schematic block diagrams, may be implemented by code. This code may be provided to a processor of a general purpose computer, a special purpose computer, or other programmable data processing apparatus to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing apparatus produce means for performing the functions / acts specified in the flow charts and / or block diagrams.

[0019] The code may be stored in a storage device that can instruct a computer, other programmable data processing apparatus, or other device to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture that includes instructions that perform the functions / acts specified in the flowcharts and / or block diagrams.

[0020] The code may be loaded into a computer, other programmable data processing apparatus, or other device to cause the computer, other programmable apparatus, or other device to perform a series of operational steps to produce a computer-implemented process such that the code executing on the computer or other programmable apparatus provides a process for performing the functions / acts specified in the flow charts and / or block diagrams.

[0021] The call-flow diagrams, flow charts, and / or block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, systems, methods, and program products according to various embodiments. In this regard, each block in the flow charts and / or block diagrams may represent a module, segment, or portion of code that includes one or more executable instructions of code for implementing the specified logical function(s).

[0022] It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may in fact be executed substantially concurrently, or the blocks may be executed in the reverse order, depending on the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks of the illustrated figures, or portions thereof.

[0023] Although various arrow types and line types may be used in the call flow diagrams, flow diagrams, and / or block diagrams, it is understood that they do not limit the scope of the corresponding embodiments. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the illustrated embodiments. For example, arrows may indicate wait or monitoring periods of unspecified duration between recited steps of the illustrated embodiments. It is also noted that each block of the block diagrams and / or flow diagrams, and combinations of blocks in the block diagrams and / or flow diagrams, may be implemented by dedicated hardware-based systems that perform the specified functions or acts, or a combination of dedicated hardware and code.

[0024] The description of the elements in each figure may refer to the elements in the procedure figures. Like numbers refer to like elements in all figures, including alternative embodiments of like elements.

[0025] Configuring a sidelink connection timer. In certain embodiments, the method may be performed using computer code embodied in a computer readable medium. In certain embodiments, an apparatus or system may include a computer readable medium including computer readable code that, when executed by a processor, causes the apparatus or system to perform at least a portion of the solutions described below.

[0026] To achieve coverage extension, a remote UE needs to select and reselect a UE-to-Network ("U2N") relay from time to time due to radio conditions and / or due to higher layer criteria. The radio conditions may be configured (or pre-configured) such that when the radio quality (e.g., Reference Signal Received Power ("RSRP") measurement) of the current serving relay UE falls below a certain threshold, the remote UE searches for candidate relays that meet the higher layer criteria (if any) and are above a certain (pre-)configured threshold.

[0027] As a first step, sidelink-based relay functionality was studied for extending sidelink / network coverage and improving power efficiency, considering a wider range of applications and services. A "Study on NR Sidelink Relay" study was conducted in a previous phase of Rel.17 and covered the enhancements and solutions required to support extending the coverage of UE-to-network relay. The results of the sidelink relay study are documented in 3GPP Technical Report ("TR") 38.836.

[0028] A remote UE, like a direct Uu UE, needs to be Radio Resource Control ("RRC") connected to utilize the services of the network, e.g., to initiate a voice call or to start a data service. For this purpose, an RRC idle remote UE needs to establish an RRC connection, an RRC inactive remote UE needs to resume an RRC connection, and when a Radio Link Failure ("RLF") occurs, the remote UE may need to re-establish an RRC connection. On the Uu interface for a direct link between the UE and a 5G / NR Node B ("gNB"), these three procedures are managed using three respective timers T300, T319, and T301, respectively.

[0029] As time management is also required for the execution of these procedures by remote UEs, it was agreed to introduce new fields in SIB1 for T300-like / T319-like / T301-like timers used by L2 remote UEs. For these timers, in addition to the existing stop conditions for legacy timers, further stop conditions for relayed scenarios are added, namely "(re)selected relay becomes unsuitable" for T300-like timers, "(re)selection of relay" for T319-like timers, and "(re)selected relay becomes unsuitable" for T301-like timers.

[0030] It was also agreed not to introduce a new T311-like timer for L2 remote UEs, but to add an additional stop condition to the legacy T311 timer for relayed scenarios, namely "upon (re)selection of a suitable relay".

[0031] Since the agreement proposes to add three new timers for said purpose in SIB1, considering that an information element ("IE") similar to UE-TimersAndConstants for sidelink ("SL") (i.e., defined as part of the definition of SIB1 in 3GPP Technical Specification ("TS") 38.331 (v16.6.0)) needs to be introduced as an option, the addition of the timers would increase the SIB1 signaling by at least 9 bits or even 10 bits.

[0032] SIB1 is a cell-specific System Information Block ("SIB") that contains information relevant when evaluating whether a UE is allowed to access the cell and defines the scheduling of other system information. SIB1 also contains radio resource configuration information common to all UEs and barring information that applies to the unified access control. In 3GPP, SIB1 is associated with the Broadcast Control Channel (BCCH) logical channel.

[0033] As specified in 3GPP TS 38.213, clause 13, SIB1 is transmitted on the downlink shared channel ("DL-SCH") (transport channel) with a period of 160 ms and a variable transmission repetition period within 160 ms, so scheduling of SIB1 is very expensive. The default transmission repetition period of SIB1 is 20 ms, but the actual transmission repetition period is up to the network implementation. For synchronization signal block ("SSB") and control resource set ("CORESET") multiplexing pattern 1, the repetition transmission period of SIB1 is 20 ms. For SSB and CORESET multiplexing patterns 2 / 3, the transmission repetition period of SIB1 is the same as the period of SSB (see 3GPP TS 38.213, clause 13). SIB1 contains information regarding the availability and scheduling of other system information blocks ("SIBs") (e.g., mapping of SIBs to SI messages, periodicity, SI window size), along with an indication of whether one or more SIBs are provided only on demand, and if so, the configuration required by the UE to perform a system information ("SI") request.

[0034] Therefore, adding 10 bits to SIB1 signaling is generally not advisable, especially when beam sweeping needs to be used by the base station for the transmission of SIB1. The present disclosure provides an alternative solution.

[0035] FIG. 1 illustrates a wireless communication system 100 for configuring a sidelink connection timer according to an embodiment of the present disclosure. In one embodiment, the wireless communication system 100 includes at least one remote unit 105, a radio access network ("RAN") 120, and a mobile core network 140. The RAN 120 and the mobile core network 140 form a mobile communication network. The RAN 120 may be comprised of a base unit 121 with which the remote unit 105 communicates using a wireless communication link 123. Even though a certain number of remote units 105, base units 121, wireless communication links 123, RAN 120, and mobile core network 140 are illustrated in FIG. 1, one skilled in the art will appreciate that any number of remote units 105, base units 121, wireless communication links 123, RAN 120, and mobile core network 140 may be included in the wireless communication system 100.

[0036] In one implementation, the RAN 120 complies with a fifth generation ("5G") system defined in 3GPP specifications. For example, the RAN 120 may be a Next Generation Radio Access Network ("NG-RAN") that implements a NR radio access technology ("RAT") and / or a Long Term Evolution ("LTE") RAT. In another example, the RAN 120 may include a non-3GPP RAT (e.g., a WLAN compliant with Wi-Fi or the Institute of Electrical and Electronics Engineers ("IEEE") 802.11 family). In another implementation, the RAN 120 complies with an LTE system defined in 3GPP specifications. However, more broadly, the wireless communication system 100 may implement any other open or proprietary communication network, such as the Worldwide Interoperability for Microwave Access ("WiMAX") or IEEE 802.16 family of standards, among other networks. This disclosure is not intended to be limited to any particular wireless communications system architecture or protocol implementation.

[0037] In one embodiment, the remote unit 105 may include a computing device such as a desktop computer, a laptop computer, a personal digital assistant ("PDA"), a tablet computer, a smartphone, a smart television (e.g., a television connected to the Internet), a smart appliance (e.g., an appliance connected to the Internet), a set-top box, a game console, a security system (including security cameras), an in-vehicle computer, a network device (e.g., a router, a switch, a modem), etc. In some embodiments, the remote unit 105 includes a wearable device such as a smart watch, a fitness band, an optical head mounted display, etc. Additionally, the remote unit 105 may be referred to as a UE, a subscriber unit, a mobile phone, a mobile station, a user, a terminal, a mobile terminal, a fixed terminal, a subscriber station, a user terminal, a wireless transmit / receive unit ("WTRU"), a device, or other terminology used in the art.

[0038] In various embodiments, the remote unit 105 includes a subscriber identity and / or identification module ("SIM") and a mobile equipment ("ME") that provides mobile termination functions (e.g., wireless transmission, handover, voice coding and decoding, error detection and correction, signaling, and access to the SIM). In certain embodiments, the remote unit 105 may include terminal equipment ("TE") and / or may be incorporated into a home appliance or device (e.g., a computing device as described above). The remote unit 105 allows a user to access network services. In various embodiments, the interface between the remote unit 105 and the network is a wireless interface. The remote unit 105 may be sub-divided into several domains, and the domains are separated by reference points. For example, the remote unit 105 may be sub-divided into a Universal Integrated Circuit Card ("UICC") domain and an ME domain. The ME domain may be further sub-divided into one or more Mobile Terminations ("MT") and TE components with connections between multiple functional groups.

[0039] The remote units 105 may communicate directly with one or more of the base units 121 in the RAN 120 by uplink ("UL") and downlink ("DL") communication signals. Furthermore, the UL and DL communication signals may be carried over a wireless communication link 123. Furthermore, the UL communication signals may include one or more uplink channels, such as a physical uplink control channel ("PUCCH") and / or a physical uplink shared channel ("PUSCH"), while the DL communication signals may include one or more DL channels, such as a physical downlink control channel ("PDCCH") and / or a physical downlink shared channel ("PDSCH"). Here, the RAN 120 is an intermediate network that provides the remote units 105 with access to the mobile core network 140.

[0040] In various embodiments, the remote units 105 may communicate directly with each other using the sidelink communication link 115 (e.g., device-to-device communication). Here, sidelink transmissions may occur on sidelink resources. The remote units 105 may be provided with different sidelink communication resources according to different allocation modes. As used herein, a "resource pool" refers to a set of resources allocated for sidelink operation. A resource pool consists of a set of resource blocks (i.e., physical resource blocks ("PRBs") over one or more time units (e.g., orthogonal frequency division multiplexing ("OFDM") symbols, subframes, slots, subslots, etc.). In some embodiments, the set of resource blocks includes PRBs that are contiguous in the frequency domain. As used herein, a PRB consists of 12 contiguous subcarriers in the frequency domain.

[0041] In some embodiments, the remote unit 105 communicates with the application server 151 via a network connection with the mobile core network 140. For example, an application 107 (e.g., a web browser, a media client, a telephone and / or a voice over Internet protocol ("VoIP") application) in the remote unit 105 may trigger the remote unit 105 to establish a protocol data unit ("PDU") session (or a packet data network ("PDN") connection) with the mobile core network 140 via the RAN 120. The PDU session represents a logical connection between the remote unit 105 and a user plane function ("UPF") 141. The mobile core network 140 then relays traffic between the remote unit 105 and the application server 151 in the packet data network 150 using the PDU session (or other data connection).

[0042] To establish a PDU session (or PDN connection), the remote unit 105 must register with the mobile core network 140 (also referred to as "attached to the mobile core network" in the context of fourth generation ("4G") systems). It should be noted that the remote unit 105 may establish one or more PDU sessions (or other data connections) with the mobile core network 140. Thus, the remote unit 105 may have at least one PDU session for communicating with the packet data network 150. The remote unit 105 may establish additional PDU sessions for communicating with other data networks and / or other communication peers.

[0043] In the context of 5G systems ("5GS"), the term "PDU session" refers to a data connection that provides end-to-end ("E2E") user plane ("UP") connectivity between a remote unit 105 and a particular data network ("DN") via the UPF 141. A PDU session supports one or more Quality of Service ("QoS") flows. In certain embodiments, there may be a one-to-one mapping between QoS flows and QoS profiles such that all packets belonging to a particular QoS flow have the same 5G QoS Identifier ("5QI").

[0044] In the context of 4G / LTE systems, such as the Evolved Packet System ("EPS"), a PDN connection (also called an EPS session) provides an E2E UP connection between a remote unit and a PDN. The PDN connection procedure establishes an EPS bearer, i.e., a tunnel between the remote unit 105 and a PDN Gateway ("PGW") (not shown in FIG. 1) in the mobile core network 140. In certain embodiments, there is a one-to-one mapping between EPS bearers and QoS profiles, such that all packets belonging to a particular EPS bearer have the same QoS Class Identifier ("QCI").

[0045] The base units 121 may be distributed across a geographic region. In certain embodiments, the base units 121 may be referred to as an access terminal, an access point, a base, a base station, a Node B ("NB"), an evolved Node B (abbreviated as eNodeB or "eNB" and also known as an evolved Universal Terrestrial Radio Access Network ("E-UTRAN") Node B), a gNB, a home Node B, a relay node, a RAN node, or any other terminology used in the art. The base units 121 are generally part of a RAN, such as the RAN 120, which may include one or more controllers communicatively coupled to one or more corresponding base units 121. These and other elements of a radio access network are not shown, but are generally familiar to those skilled in the art. The base units 121 connect to a mobile core network 140 via the RAN 120.

[0046] The base unit 121 may serve multiple remote units 105 in a serving area, e.g., a cell or a sector of a cell, via wireless communication link 123. The base unit 121 may directly communicate with one or more of the remote units 105 by communication signals. In general, the base unit 121 transmits DL communication signals to serve the remote units 105 in the time, frequency, and / or spatial domains. Furthermore, the DL communication signals may be carried on the wireless communication link 123. The wireless communication link 123 may be any suitable carrier in a licensed or unlicensed radio spectrum. The wireless communication link 123 facilitates communication between one or more of the remote units 105 and / or one or more of the base units 121.

[0047] It should be noted that during NR operation over an unlicensed spectrum (referred to as "NR-U"), the base unit 121 and the remote unit 105 communicate over an unlicensed (i.e., shared) radio spectrum. Similarly, during LTE operation over an unlicensed spectrum (referred to as "LTE-U"), the base unit 121 and the remote unit 105 also communicate over an unlicensed (i.e., shared) radio spectrum.

[0048] In one embodiment, the mobile core network 140 is a 5G Core Network ("5GC") or Evolved Packet Core ("EPC") that may be coupled to a packet data network 150, such as the Internet and private data networks, among other data networks. The remote units 105 may have a subscription or other account with the mobile core network 140. In various embodiments, each mobile core network 140 belongs to a single mobile network operator ("MNO") and / or public land mobile network ("PLMN"). This disclosure is not intended to be limited to any particular wireless communications system architecture or protocol implementation.

[0049] The mobile core network 140 includes several network functions ("NFs"). As shown, the mobile core network 140 includes at least one UPF 141. The mobile core network 140 also includes multiple control plane ("CP") functions, including but not limited to an Access and Mobility Management Function ("AMF") 143, a Session Management Function ("SMF") 145, a Policy Control Function ("PCF") 147, a Unified Data Management function ("UDM"), and a User Data Repository ("UDR", also referred to as "Unified Data Repository"), that serve the RAN 120. Although a particular number and type of network functions are shown in FIG. 1, one skilled in the art will recognize that any number and type of network functions may be included in the mobile core network 140.

[0050] The UPF 141 is responsible for packet routing and forwarding, packet inspection, QoS handling, and external PDU sessions for interconnecting data networks ("DNs") in the 5G architecture. The AMF 143 is responsible for non-access stratum ("NAS") signaling termination, NAS encryption and integrity protection, registration management, connection management, mobility management, access authentication and authorization, and security context management. The SMF 145 is responsible for session management (i.e., session establishment, modification, release), remote unit (i.e., UE) Internet Protocol ("IP") address allocation and management, DL data notification, and traffic steering configuration of the UPF 141 for proper traffic routing.

[0051] The PCF 147 is responsible for the unified policy framework, providing policy rules to the CP function, and access subscription information for policy decisions in the UDR. The UDM is responsible for Authentication and Key Agreement (AKA) credential generation, user identification, access authorization, and subscription management. The UDR is a repository of subscriber information and may be used to provide services to many network functions. For example, the UDR may store subscription data, policy related data, subscriber related data that is allowed to be exposed to third party applications, etc. In some embodiments, the UDM is co-located with the UDR and is shown as a combined entity "UDM / UDR" 149.

[0052] In various embodiments, the mobile core network 140 may also include a Network Repository Function ("NRF") (which provides registration and discovery of Network Function ("NF") services, enabling NFs to identify each other's appropriate services and communicate with each other via application programming interfaces ("APIs")), a Network Exposure Function ("NEF") (responsible for making network data and resources easily accessible to customers and network partners), an Authentication Server Function ("AUSF"), or other NFs defined for 5GC. When present, the AUSF may act as an authentication server and / or authentication proxy, thereby enabling the AMF 143 to authenticate the remote unit 105. In certain embodiments, the mobile core network 140 may include an Authentication, Authorization, and Accounting ("AAA") server.

[0053] In various embodiments, the mobile core network 140 supports different types of mobile data connections and different types of network slices, each of which utilizes a particular network slice. Here, a "network slice" refers to a portion of the mobile core network 140 optimized for a particular traffic type or communication service. For example, one or more network slices may be optimized for enhanced mobile broadband ("eMBB") services. As another example, one or more network slices may be optimized for ultra-reliable low-latency communication ("URLLC") services. In other examples, a network slice may be optimized for machine type communication ("MTC") services, massive MTC ("mMTC") services, Internet of Things ("IoT") services. In still other examples, a network slice may be deployed for a particular application service, vertical service, a particular use case, or the like.

[0054] A network slice instance may be specified by a single-network slice selection assistance information ("S-NSSAI"), while a set of network slices that the remote unit 105 is authorized to use is specified by a network slice selection assistance information ("NSSAI"), where "NSSAI" refers to a vector value that includes one or more S-NSSAI values. In certain embodiments, various network slices may include separate instances of network functions, such as the SMF 145 and the UPF 141. In some embodiments, different network slices may share some common network functions, such as the AMF 143. For ease of illustration, different network slices are not shown in FIG. 1, but their support is assumed.

[0055] To facilitate configuring the sidelink connection timers, the base unit 121 may transmit a sidelink configuration to the remote unit 105, which uses the sidelink configuration to identify the associated sidelink connection timers and / or the associated sidelink communication resources. In various embodiments, the sidelink configuration may be transmitted within an SI, such as SIB1 or another SIB, that contains sidelink configuration information.

[0056] In various embodiments, the remote unit 105 may be provided with different sidelink communication resources for different allocation modes. Mode 1 corresponds to an NR-based network-scheduled sidelink communication mode, where the in-coverage RAN 120 indicates resources for use in sidelink operations, including resources from one or more resource pools. Mode 2 corresponds to an NR-based UE-scheduled sidelink communication mode (i.e., UE-autonomous selection), where the remote unit 105 selects a resource pool and resources therein from a set of candidate pools. Mode 3 corresponds to an LTE-based network-scheduled sidelink communication mode. Mode 4 corresponds to an LTE-based UE-scheduled sidelink communication mode (i.e., UE-autonomous selection).

[0057] Although FIG. 1 shows components of a 5G RAN and a 5G core network, the described embodiments for configuring a sidelink connection timer apply to other types of communication networks and RATs, including variants of IEEE 802.11, Global System for Mobile Communications ("GSM") (i.e., 2G digital cellular networks), General Packet Radio Service ("GPRS"), Universal Mobile Telecommunications System ("UMTS"), variants of LTE, CDMA2000, Bluetooth, ZigBee, Sigfox, etc.

[0058] Further, in variants of LTE where the mobile core network 140 is the EPC, the depicted network functions may be replaced by appropriate EPC entities such as a Mobility Management Entity ("MME"), a Serving Gateway ("SGW"), a PGW, a Home Subscriber Server ("HSS"), etc. For example, the AMF 143 may be mapped to the MME, the SMF 145 may be mapped to the control plane portion of the PGW and / or to the MME, the UPF 141 may be mapped to the SGW and the user plane portion of the PGW, the UDM / UDR 149 may be mapped to the HSS, etc.

[0059] In the following description, the term "RAN node" is used for a base station / base unit, but it may be replaced by any other radio access node, e.g., gNB, ng-eNB, eNB, base station ("BS"), base station unit, access point ("AP"), NR BS, 5G NB, transmission and reception point ("TRP"), etc. Additionally, the term "UE" is used for a mobile station / remote unit, but it may be replaced by any other remote device, e.g., remote unit, MS, ME, etc.

[0060] Furthermore, the operations are primarily described in the context of 5G NR, however, the solutions / methods described below are equally applicable to other mobile communication systems that configure sidelink connection timers.

[0061] FIG. 2 illustrates an NR protocol stack 200 according to an embodiment of the present disclosure. FIG. 2 illustrates a UE 205, a RAN node 210, and an AMF 215 in a 5G core network ("5GC"), which are representative of a set of remote units 105 interacting with a base unit 121 and a mobile core network 140. As shown, the NR protocol stack 200 includes a user plane protocol stack 201 and a control plane protocol stack 203. The user plane protocol stack 201 includes a physical ("PHY") layer 220, a medium access control ("MAC") sublayer 225, a radio link control ("RLC") sublayer 230, a packet data convergence protocol ("PDCP") sublayer 235, and a service data adaptation protocol ("SDAP") sublayer 240. The control plane protocol stack 203 includes a PHY layer 220, a MAC sublayer 225, an RLC sublayer 230, and a PDCP sublayer 235. The control plane protocol stack 203 also includes an RRC layer 245 and a NAS layer 250.

[0062] The access stratum ("AS") layer 255 (also referred to as the "AS protocol stack") of the user plane protocol stack 201 is composed of at least the SDAP, PDCP, RLC, and MAC sublayers, and a physical layer. The AS layer 260 of the control plane protocol stack 203 is composed of at least the RRC, PDCP, RLC, MAC sublayers, and a physical layer. Layer 2 ("L2") is divided into the SDAP, PDCP, RLC, and MAC sublayers. Layer 3 ("L3") includes the RRC layer 245 and the NAS layer 250 of the control plane, including, for example, the IP layer and / or the PDU layer (not shown) of the user plane. L1 and L2 are referred to as "lower layers," while L3 and above (e.g., transport layer, application layer) are referred to as "higher layers" or "upper layers."

[0063] The PHY layer 220 provides transport channels to the MAC sublayer 225. The PHY layer 220 may perform a beam failure detection procedure using an energy detection threshold. In a particular embodiment, the PHY layer 220 may send an indication of beam failure to the MAC entity of the MAC sublayer 225. The MAC sublayer 225 provides logical channels to the RLC sublayer 230. The RLC sublayer 230 provides RLC channels to the PDCP sublayer 235. The PDCP sublayer 235 provides radio bearers to the SDAP sublayer 240 and / or the RRC layer 245. The SDAP sublayer 240 provides QoS flows to the core network (e.g., 5GC). The RRC layer 245 provides functions for adding, modifying, and releasing carrier aggregation and / or dual connectivity. The RRC layer 245 also manages the establishment, configuration, maintenance, and release of signaling radio bearers ("SRBs") and data radio bearers ("DRBs").

[0064] The NAS layer 250 is between the UE 205 and the AMF 215 in the 5GC. NAS messages are passed transparently through the RAN. The NAS layer 250 is used to manage the establishment of communication sessions and maintain continuous communication with the UE 205 as the UE 205 moves between different cells of the RAN. In contrast, the AS layers 255 and 260 are between the UE 205 and the RAN (i.e., the RAN node 210) and carry information over the wireless part of the network. Although not shown in FIG. 2, an IP layer resides above the NAS layer 250, a transport layer resides above the IP layer, and an application layer resides above the transport layer.

[0065] The MAC sublayer 225 is the lowest sublayer of the L2 architecture of the NR protocol stack. The MAC sublayer 225's connection with the PHY layer 220 below is via transport channels, and its connection with the RLC sublayer 230 above is via logical channels. Thus, the MAC sublayer 225 performs multiplexing and demultiplexing between logical and transport channels, i.e., the MAC sublayer 225 on the transmitting side builds MAC PDUs (also known as transport blocks ("TBs")) from MAC service data units ("SDUs") received over logical channels, and the MAC sublayer 225 on the receiving side recovers MAC SDUs from MAC PDUs received over transport channels.

[0066] The MAC sublayer 225 provides data transfer services for the RLC sublayer 230 over logical channels that are either control logical channels carrying control data (e.g., RRC signaling) or traffic logical channels carrying user plane data. Data from the MAC sublayer 225 is in turn transferred to and from the PHY layer 220 over transport channels classified as UL or DL. Data is multiplexed into the transport channels depending on how it is transmitted over the air wirelessly.

[0067] The PHY layer 220 is responsible for the actual transmission of data and control information over the air interface, i.e., the PHY layer 220 carries all information from the MAC transport channel over the air interface on the transmit side. Some of the important functions performed by the PHY layer 220 include coding and modulation, link adaptation (e.g., Adaptive Modulation and Coding ("AMC")), power control, cell search and random access (for initial synchronization and handover purposes), and other measurements (within 3GPP systems (i.e., NR and / or LTE systems) and between systems) for the RRC layer 245. The PHY layer 220 performs transmission based on transmission parameters such as modulation scheme, coding rate (i.e., modulation and coding scheme ("MCS")), number of PRBs, etc.

[0068] U2N relays are a potential means to increase the coverage of a serving cell, for example, using one or many hops. For U2N coverage extension, Uu coverage reachability is required for a UE to reach a server in the PDN network or a peer UE outside of the proximity area. A U2N relay UE is an in-coverage implementation of a UE 205 that extends the coverage of a RAN node 210. Through a U2N relay UE, the RAN node 210 can serve an otherwise out-of-coverage implementation of a UE 205, called a U2N remote UE.

[0069] In some embodiments, the U2N relay UE acts as an L3 relay (also referred to as an IP relay), where communication between the RAN node 210 and the U2N remote UE via the L3 relay is via a Uu link (e.g., a first interface) between the RAN node 210 and the U2N relay UE, and a PC5 link (e.g., a second interface) between the U2N relay UE and the U2N remote UE. In such an embodiment, the protocol stack of the U2N relay UE may include SDAP, RRC, PDCP, RLC, MAC, and PHY layers that interact with corresponding layers of the RAN node 210 via the first interface (i.e., corresponding to the Uu link) and also interact with corresponding layers of the U2N remote UE via the second interface (i.e., corresponding to the PC5 link).

[0070] In some embodiments, the U2N relay UE acts as an L2 relay. In a particular embodiment, the U2N relay UE acting as an L2 relay performs relay functions under the PDCP sublayer 235, and thus the U2N relay UE does not perform PDCP, RRC, and SDAP functions with respect to communications between the RAN node 210 and the U2N remote UE. In such an embodiment, the protocol stack of the U2N relay UE may include RLC sublayer 230, MAC sublayer 225, and PHY layer 220 entities that interact with corresponding layers of the RAN node 210 via a first interface and with corresponding layers of the U2N remote UE via a second interface. However, with respect to the PDCP sublayer 235, SDAP sublayer 240, and RRC layer 245, link endpoints are between the RAN node 210 and the U2N remote UE.

[0071] In some embodiments, the U2N relay UE acts as an L1 relay with HARQ functionality (also called an Amplify and Forward relay). In a particular embodiment, the protocol stack of the U2N relay UE may include a PHY layer 220 and a HARQ entity (i.e., of the MAC sublayer 225) that interacts with corresponding layers of the RAN node 210 via a first interface and with corresponding layers of the U2N remote UE via a second interface. However, with respect to the remaining layers, link endpoints are between the RAN node 210 and the U2N remote UE.

[0072] It should be noted that the above description of relays is exemplary and that a U2N relay UE is not limited to the implementation of relays described above. Thus, a U2N relay UE may implement a different protocol stack and / or link endpoints than those described above according to the solutions described below.

[0073] 3 illustrates an example procedure 300 for establishing an RRC connection according to an embodiment of the present disclosure. The procedure 300 includes a U2N sidelink remote UE (i.e., denoted as "remote UE") 305 (e.g., an instance of an out-of-coverage remote unit 105 or out-of-coverage UE 205), a U2N sidelink relay UE (i.e., denoted as "relay UE") 310 (e.g., an instance of an in-coverage remote unit 105 or UE 205), and a RAN node 210 (e.g., an instance of a base unit 121). The procedure 300 enables the U2N sidelink remote UE 305 to acquire SIB1 (and optionally other SIBs) via the U2N sidelink relay UE 310 and initiate an RRC connection request with the RAN node 210.

[0074] In step 1, the U2N sidelink remote UE 305 receives SIB1 via the U2N sidelink relay UE 310 (see messaging 315). Optionally, the U2N sidelink remote UE 305 may also receive one or more additional SIBs (denoted as "SIB_X" in FIG. 3) via the U2N sidelink relay UE 310. In various embodiments, the RAN node 210 broadcasts SIB1, and the U2N sidelink relay UE 310 relays SIB1 to the U2N sidelink remote UE 305, where SIB1 is assumed to include sidelink connection timer information, as described in more detail below. In a particular embodiment, the RAN node 210 may also broadcast one or more additional SIBs. In other embodiments, one or more of the additional SIBs (i.e., SIB_X) may constitute on-demand SIs, and the U2N sidelink relay UE 310 may request and receive the additional SIBs from the RAN node 210 (not shown in FIG. 3).

[0075] As used herein, "on-demand" SI refers to SI that is not periodically broadcast by the RAN (i.e., by the RAN node 210). Rather, a requesting UE (e.g., U2N sidelink relay UE 310) must request a particular SI from the RAN, at which time the RAN (i.e., RAN node 210) transmits the requested SI to the requesting UE (e.g., U2N sidelink relay UE 310) in one or more SIBs.

[0076] In step 2, the U2N sidelink remote UE 305 determines the SL connection timer based on, for example, information in SIB1 (see block 320). Although Figure 3 focuses primarily on the establishment of an RRC connection, the steps of receiving and / or determining the SL connection timer apply to sidelink-specific versions of all three timers T300, T301, and T319 - also referred to as "SL connection timers".

[0077] In step 3a, the U2N sidelink remote UE 305 sends a setup request message (e.g., RRCSetupRequest) to the U2N sidelink relay UE 310 (see messaging 325). In a particular embodiment, the U2N sidelink remote UE 305 requests an RRC connection over an uplink shared channel ("UL-SCH"). In a particular embodiment, the setup request message (e.g., RRCSetupRequest) includes an establishment cause parameter. In step 3b, the U2N sidelink relay UE 310 forwards the setup request message (i.e., RRCSetupRequest) to the RAN node 210 (see messaging 330).

[0078] It should be noted that the U2N sidelink remote UE 305 starts a sidelink-specific T300 connection timer when sending a setup request message (e.g., RRCSetupRequest) (see block 335). When the sidelink-specific T300 connection timer expires, the U2N sidelink remote UE 305 takes actions as specified in section 5.3.3.7 of 3GPP TS 38.331 (v16.6.0), including informing higher layers about the failure to establish an RRC connection.

[0079] In step 4a-1, the RAN node 210 sends a setup message (e.g., RRCSetup) to the U2N sidelink relay UE 310 (see messaging 340), where the network establishes the SRBs and DRBs based on the establishment cause parameters. In a particular embodiment, the setup message is sent over a downlink shared channel ("DL-SCH"). In step 4a-2, the U2N sidelink relay UE 310 forwards the setup message (e.g., RRCSetup) to the U2N sidelink remote UE 305 (see messaging 345).

[0080] Alternatively, in step 4b-1, the RAN node 210 sends a rejection message (e.g., RRCReject) to the U2N sidelink relay UE 310 (see messaging 350). In step 4b-2, the U2N sidelink relay UE 310 forwards the rejection message (e.g., RRCReject) to the U2N sidelink remote UE 305 (see messaging 355).

[0081] In step 5a-1, the U2N sidelink remote UE 305 acknowledges the setup message by sending a connection complete message (e.g., RRCSetupComplete) to the U2N sidelink relay UE 310 (see messaging 360). In step 5a-2, the U2N sidelink relay UE 310 forwards the connection complete message (e.g., RRCSetupComplete) to the RAN node 210 (see messaging 365). The above-mentioned messages and their contents are described in more detail in 3GPP TS 38.331 (v16.6.0), which is incorporated herein by reference.

[0082] 4 illustrates an example procedure 400 for re-establishment of an RRC connection according to an embodiment of the present disclosure. The procedure 400 includes a U2N sidelink remote UE (i.e., denoted as "remote UE") 305, a U2N sidelink relay UE (i.e., denoted as "relay UE") 310, and a RAN node 210. The procedure 400 enables the U2N sidelink remote UE 305 to acquire SIB1 (and optionally other SIBs) via the U2N sidelink relay UE 310 and re-establish an RRC connection with the RAN node 210. In various embodiments, the U2N sidelink remote UE 305 initiates the procedure 400 for re-establishment of an RRC connection when one of the following conditions is met: When detecting a radio link failure, or When a handover fails, or When a mobility from E-UTRA failure occurs, or When there is an indication from a lower layer that an integrity check has failed, or -When RRC CONNECTION RECONFIGURATION fails.

[0083] In step 1, the U2N sidelink remote UE 305 receives SIB1 via the U2N sidelink relay UE 310 (see messaging 405). Optionally, the U2N sidelink remote UE 305 may also receive one or more additional SIBs (denoted as "SIB_X" in FIG. 4) via the U2N sidelink relay UE 310. In various embodiments, the RAN node 210 broadcasts SIB1, and the U2N sidelink relay UE 310 relays SIB1 to the U2N sidelink remote UE 305, where SIB1 is assumed to include sidelink connection timer information, as described in more detail below. In a particular embodiment, the RAN node 210 may also broadcast one or more additional SIBs. In other embodiments, one or more of the additional SIBs (i.e., SIB_X) may constitute on-demand SIs, and the U2N sidelink relay UE 310 may request and receive the additional SIBs from the RAN node 210 (not shown in FIG. 4).

[0084] In step 2, the U2N sidelink remote UE 305 determines the SL connection timer based on, for example, information in SIB1 (see block 410). Although Figure 4 focuses primarily on the re-establishment of the RRC connection, the steps of receiving and / or determining the SL connection timer apply to sidelink specific versions of all three timers T300, T301 and T319.

[0085] In step 3a, the U2N sidelink remote UE 305 sends a re-establishment request message (e.g., RRCReestablishmentRequest) to the U2N sidelink relay UE 310 (see messaging 415). In a particular embodiment, the U2N sidelink remote UE 305 requests re-establishment of an RRC connection over the UL-SCH. In a particular embodiment, the re-establishment request message (e.g., RRCReestablishmentRequest) includes a re-establishment cause parameter. In step 3b, the U2N sidelink relay UE 310 forwards the re-establishment request message (i.e., RRCReestablishmentRequest) to the RAN node 210 (see messaging 420).

[0086] It should be noted that when the U2N sidelink remote UE 305 sends a re-establishment request message (e.g., RRCReestablishmentRequest), it starts a sidelink-specific T301 connection timer (see block 425). When the sidelink-specific T301 connection timer expires, the U2N sidelink remote UE 305 takes actions as specified in section 5.3.11 of 3GPP TS 38.331, including going to RRC_IDLE with release cause "RRC connection failure".

[0087] In step 4a-1, the RAN node 210 sends a re-establishment message (e.g., RRCReestablishment) to the U2N sidelink relay UE 310 (see messaging 430). In some embodiments, the network re-establishes the SRBs and DRBs based on the re-establishment cause parameter. In particular embodiments, the re-establishment message is sent over a downlink shared channel ("DL-SCH"). In step 4a-2, the U2N sidelink relay UE 310 forwards the re-establishment message (e.g., RRCReestablishment) to the U2N sidelink remote UE 305 (see messaging 435).

[0088] Alternatively, a fallback to RRC establishment may be required in response to the re-establishment message. In step 4b-1, the RAN node 210 sends a setup message (e.g., RRCSetup) to the U2N sidelink relay UE 310 (see messaging 440), where the network establishes SRBs and DRBs based on the re-establishment cause parameters. In a particular embodiment, the setup message is sent over DL-SCH. In step 4b-2, the U2N sidelink relay UE 310 forwards the setup message (e.g., RRCSetup) to the U2N sidelink remote UE 305 (see messaging 445).

[0089] In step 5a-1, the U2N sidelink remote UE 305 acknowledges the re-establishment message by sending a re-establishment completion message (e.g., RRCReestablishmentComplete) to the U2N sidelink relay UE 310 (see messaging 450). In step 5a-2, the U2N sidelink relay UE 310 forwards the re-establishment completion message (e.g., RRCReestablishmentComplete) to the RAN node 210 (see messaging 455).

[0090] In the alternative where a fallback to RRC establishment is required, in step 5b-1, the U2N sidelink remote UE 305 acknowledges the setup message by sending a connection complete message (e.g., RRCSetupComplete) to the U2N sidelink relay UE 310 (see messaging 460). In step 5b-2, the U2N sidelink relay UE 310 forwards the connection complete message (e.g., RRCSetupComplete) to the RAN node 210 (see messaging 465). The above-mentioned messages and their contents are described in more detail in 3GPP Technical Specification ("TS") 38.331.

[0091] 5 illustrates an example procedure 500 for resumption of an RRC connection according to an embodiment of the present disclosure. The procedure 500 includes a U2N sidelink remote UE (i.e., denoted as "remote UE") 305, a U2N sidelink relay UE (i.e., denoted as "relay UE") 310, and a RAN node 210. The procedure 500 enables the U2N sidelink remote UE 305 to acquire SIB1 (and optionally other SIBs) via the U2N sidelink relay UE 310 and resume an interrupted RRC connection with the RAN node 210. In various embodiments, the U2N sidelink remote UE 305 initiates the procedure 500 when a higher layer or an AS layer requests resumption of an interrupted RRC connection (e.g., when responding to a RAN paging or triggering a RAN-based Notification Area update while the U2N sidelink remote UE 305 is in an RRC_INACTIVE state).

[0092] In step 1, the U2N sidelink remote UE 305 receives SIB1 via the U2N sidelink relay UE 310 (see messaging 505). Optionally, the U2N sidelink remote UE 305 may also receive one or more additional SIBs (denoted as "SIB_X" in FIG. 5) via the U2N sidelink relay UE 310. In various embodiments, the RAN node 210 broadcasts SIB1, and the U2N sidelink relay UE 310 relays SIB1 to the U2N sidelink remote UE 305, where SIB1 is assumed to include sidelink connection timer information, as described in more detail below. In a particular embodiment, the RAN node 210 may also broadcast one or more additional SIBs. In other embodiments, one or more of the additional SIBs (i.e., SIB_X) may constitute on-demand SIs, and the U2N sidelink relay UE 310 may request and receive the additional SIBs from the RAN node 210 (not shown in FIG. 5).

[0093] In step 2, the U2N sidelink remote UE 305 determines the SL connection timer based on, for example, information in SIB1 (see block 510). Although Figure 5 focuses primarily on the resumption of the RRC connection, the steps of receiving and / or determining the SL connection timer apply to sidelink specific versions of all three timers T300, T301 and T319.

[0094] In step 3a, the U2N sidelink remote UE 305 sends a resume request message (e.g., RRCResumeRequest or RRCResumeRequest1) to the U2N sidelink relay UE 310 (see messaging 515). In a particular embodiment, the U2N sidelink remote UE 305 requests to resume the RRC connection over the UL-SCH. In a particular embodiment, the resume request message (e.g., RRCResumeRequest or RRCResumeRequest1) includes a resume cause parameter. In step 3b, the U2N sidelink relay UE 310 forwards the resume request message (i.e., RRCResumeRequest or RRCResumeRequest1) to the RAN node 210 (see messaging 520).

[0095] It should be noted that when the U2N sidelink remote UE 305 sends a resume request message (e.g., RRCResumeRequest or RRCResumeRequest1), it starts a sidelink specific T319 connection timer (see block 525). When the sidelink specific T319 connection timer expires, the U2N sidelink remote UE 305 takes actions as specified in section 5.3.13.5 of 3GPP TS 38.331, including going to RRC_IDLE with release cause "RRC Connection Failure".

[0096] In step 4a-1, the RAN node 210 sends a resume message (e.g., RRCResume) to the U2N sidelink relay UE 310 (see messaging 530). In some embodiments, the network resumes the SRBs and DRBs based on the resume cause parameter. In a particular embodiment, the resume message is transmitted over a downlink shared channel ("DL-SCH"). In step 4a-2, the U2N sidelink relay UE 310 forwards the resume message (e.g., RRCResume) to the U2N sidelink remote UE 305 (see messaging 535).

[0097] Alternatively, in response to the resume message, a fallback to RRC establishment may be required. In step 4b-1, the RAN node 210 sends a setup message (e.g., RRCSetup) to the U2N sidelink relay UE 310 (see messaging 540), where the network establishes SRBs and DRBs based on the resume cause parameter. In a particular embodiment, the setup message is sent over DL-SCH. In step 4b-2, the U2N sidelink relay UE 310 forwards the setup message (e.g., RRCSetup) to the U2N sidelink remote UE 305 (see messaging 545).

[0098] In step 5a-1, the U2N sidelink remote UE 305 acknowledges the resume message by sending a resume complete message (e.g., RRCResumeComplete) to the U2N sidelink relay UE 310 (see messaging 550). In step 5a-2, the U2N sidelink relay UE 310 forwards the resume complete message (e.g., RRCResumeComplete) to the RAN node 210 (see messaging 555).

[0099] In the alternative where fallback to RRC establishment is required, in step 5b-1, the U2N sidelink remote UE 305 acknowledges the setup message by sending a connection complete message (e.g., RRCSetupComplete) to the U2N sidelink relay UE 310 (see messaging 560). In step 5b-2, the U2N sidelink relay UE 310 forwards the connection complete message (e.g., RRCSetupComplete) to the RAN node 210 (see messaging 565). The above-mentioned messages and their contents are described in more detail in 3GPP Technical Specification ("TS") 38.331.

[0100] 6 illustrates an example procedure 600 for resumption of an RRC connection followed by a network-initiated release according to an embodiment of the present disclosure. The procedure 600 includes a U2N sidelink remote UE (i.e., denoted as "remote UE") 305, a U2N sidelink relay UE (i.e., denoted as "relay UE") 310, and a RAN node 210. The procedure 600 enables the U2N sidelink remote UE 305 to acquire SIB1 (and optionally other SIBs) via the U2N sidelink relay UE 310 and request to resume a suspended RRC connection with the RAN node 210. However, in the procedure 600, the network (i.e., the RAN node 210) initiates an RRC connection release procedure to transition the U2N sidelink remote UE 305 from a connected state (e.g., an RRC_CONNECTED state) to an unconnected state (e.g., an RRC_IDLE state). As discussed above, the U2N sidelink remote UE 305 of the U2N sidelink may initiate the procedure when higher layers or the AS layer request resumption of an interrupted RRC connection.

[0101] In step 1, the U2N sidelink remote UE 305 of the U2N sidelink receives SIB1 via the U2N sidelink relay UE 310 (see messaging 605). Optionally, the U2N sidelink remote UE 305 of the U2N sidelink may also receive one or more additional SIBs (denoted as "SIB_X" in FIG. 6) via the U2N sidelink relay UE 310. In various embodiments, the RAN node 210 broadcasts SIB1, and the U2N sidelink relay UE 310 relays SIB1 to the U2N sidelink remote UE 305 of the U2N sidelink. Here, SIB1 is assumed to include sidelink connection timer information, as described in more detail below. In a particular embodiment, the RAN node 210 may also broadcast one or more additional SIBs. In other embodiments, one or more of the additional SIBs (i.e., SIB_X) may constitute on-demand SIs, and the U2N sidelink relay UE 310 may request and receive the additional SIBs from the RAN node 210 (not shown in FIG. 6).

[0102] In step 2, the U2N sidelink remote UE 305 of the U2N sidelink determines the SL connection timer based on, for example, information in SIB1 (see block 610). Although Figure 6 focuses primarily on the resumption of the RRC connection, the steps of receiving and / or determining the SL connection timer apply to sidelink specific versions of all three timers T300, T301 and T319.

[0103] In step 3a, the U2N sidelink remote UE 305 of the U2N sidelink sends a resume request message (e.g., RRCResumeRequest or RRCResumeRequest1) to the U2N sidelink relay UE 310 (see messaging 615). In a particular embodiment, the U2N sidelink remote UE 305 of the U2N sidelink requests to resume the RRC connection over the UL-SCH. In a particular embodiment, the resume request message (e.g., RRCResumeRequest or RRCResumeRequest1) includes a resume cause parameter. In step 3b, the U2N sidelink relay UE 310 forwards the resume request message (i.e., RRCResumeRequest or RRCResumeRequest1) to the RAN node 210 (see messaging 620).

[0104] It should be noted that the U2N sidelink remote UE 305 of the U2N sidelink starts a sidelink specific T319 connection timer when sending a resume request message (e.g., RRCResumeRequest or RRCResumeRequest1) (see block 625). When the sidelink specific T319 connection timer expires, the U2N sidelink remote UE 305 of the U2N sidelink takes actions as specified in section 6.3.11 of 3GPP TS 38.331, including going to RRC_IDLE with release cause "RRC connection failure".

[0105] In step 4a-1, the RAN node 210 sends a release message (e.g., RRCRelease) to the U2N sidelink relay UE 310 (see messaging 630). The network then triggers the U2N sidelink remote UE 305 of the U2N sidelink to release the RRC connection and transition from a connected state (e.g., RRC_CONNECTED state) to an idle state (e.g., RRC_IDLE state). In step 4a-2, the U2N sidelink relay UE 310 forwards the release message (e.g., RRCRelease) to the U2N sidelink remote UE 305 of the U2N sidelink (see messaging 635).

[0106] Alternatively, in step 4b-1, the RAN node 210 sends a release message (e.g., RRCRelease) including a suspend configuration to the U2N sidelink relay UE 310 (see messaging 640). Here, the release message (e.g., RRCRelease with suspend configuration) triggers the U2N sidelink remote UE 305 of the U2N sidelink to suspend the RRC connection and transition from RRC_CONNECTED state to RRC_IDLE state. In step 4b-2, the U2N sidelink relay UE 310 forwards the release message (e.g., RRCRelease) to the U2N sidelink remote UE 305 of the U2N sidelink (see messaging 645). The above-mentioned messages and their contents are described in more detail in 3GPP Technical Specification ("TS") 38.331.

[0107] According to an embodiment of the first solution, the SL connection timer is not signaled in SIB1, but instead in a different SIB, which could be, for example, SIB12 (carrying the NR sidelink communication configuration), SIB13 (carrying the configuration of vehicle-to-everything ("V2X") sidelink communication defined in 3GPP TS 36.331, where V2X communication encompasses both vehicle-to-vehicle ("V2V") and vehicle-to-infrastructure ("V2I")), SIB14 (carrying the configuration of V2X sidelink communication defined in 3GPP TS 36.331, which may be used in conjunction with the configuration of V2X sidelink communication included in SIB13), or a SIB containing other information required for the operation of the U2N relay.

[0108] Connection timers in the context of Uu have the following associated behavior, as shown in Table 1.

[0109] [Table 1]

[0110] FIG. 7 illustrates an example Abstract Syntax Notation One ("ASN.1") representation of the ue-TimersAndConstants IE according to an embodiment of the present disclosure. The Uu specific connection timers are broadcast in SIB1 within the IE called ue-TimersAndConstants shown in FIG. 7. Even though the procedure is performed using a U2N sidelink relay UE 310 to reach the RAN node 210 in both UL and DL directions, the SL connection timers in the sidelink context will have a similar UE behavior. As already indicated, the connection timers required by the SL remote UE are T300, T301, and T319.

[0111] FIG. 8 illustrates an example ASN.1 representation of an IE including SL connection timers for the SL / PC5 interface according to an embodiment of the present disclosure. In a particular embodiment, these SL connection timers may be signaled in an additional SIB different from SIB1, e.g., SIB12, SIB13, SIB14, or another SIB including information required for the operation of the U2N relay. In one embodiment, the IE including connection timers (e.g., SL connection timers) and constants used by the U2N remote UE is called sl-UE-TimersAndConstants. In other embodiments, the IE including connection timers and constants used by the U2N remote UE for use by the sidelink remote UE (e.g., U2N sidelink remote UE 305 of the U2N sidelink) may be called by another name. As already indicated, the SL connection timers required by the SL remote UE include SL specific T300, SL specific T301, and SL specific T319.

[0112] In one implementation of the first solution, the U2N sidelink relay UE 310 extracts the SL connection timer (i.e., from the IE sl-UE-TimersAndConstants or a similar IE) and forwards this information together with the other contents of SIB1 to the U2N sidelink remote UE 305 on the U2N sidelink.

[0113] In another implementation of the first solution, the U2N sidelink relay UE 310 forwards the corresponding SIB to the U2N sidelink U2N sidelink remote UE 305. In one embodiment, this is done before establishment of a PC5 RRC connection between the U2N sidelink U2N sidelink remote UE 305 and the U2N sidelink relay UE 310, e.g., in a Discovery message sent by the U2N sidelink relay UE 310. In another embodiment, the U2N sidelink relay UE 310 signals the SL connection timer to the U2N sidelink U2N sidelink remote UE 305 after the PC5 RRC connection is established, e.g., using a PC5 RRC reconfiguration message.

[0114] The first solution has the advantage that no additional burden in SIB1 is required and the U2N sidelink remote UE 305 of the U2N sidelink can directly use the signaled values. In some embodiments, the SL connection timers signaled in the additional SIB may be incomplete, i.e. one or more of SL specific T300, SL specific T301 or SL specific T319 may not be present in the additional SIB. In such embodiments, the missing SL specific timers may be derived from the corresponding Uu specific connection timers. In one embodiment, for SL specific timers whose values ​​are missing from the additional SIB, the value of the Uu specific connection timer is used as is. In another embodiment, an offset is added to the value of the Uu specific connection timer as described in the second solution.

[0115] According to a second solution embodiment, the sidelink remote UE (e.g., U2N sidelink remote UE 305 for U2N sidelink) can derive the SL connection timer value by receiving SIB1 (and thereby the IE ue-TimersAndConstants) and adding a fixed offset (e.g., 50 ms), called "PC5 additional offset time", to the corresponding Uu timer. In some embodiments, the additional delay on the PC5 interface is constant for all connection timers (T300, T301, T319, etc.). Therefore, from a signaling point of view, it is possible to simply use this offset for the Uu-specific connection timers. In some embodiments, the timer-specific additional delay is signaled to the SL remote UE, so that each SL-specific connection timer (e.g., SL-specific T300, SL-specific T301, and SL-specific T319) can have the same--or a different--additional offset for the corresponding Uu-specific connection timer.

[0116] In one implementation of the second solution, the value of the PC5 additional time offset is specified and therefore does not require any signaling. However, to give the network some flexibility to take into account local radio conditions, congestion, Mode 1 / Mode 2 resource allocation, etc., in the second implementation, the PC5 additional time offset may be determined by the network and signaled in SIB1.

[0117] In this manner, the method of derivation of the SL connection timer can minimize additional SIB1 signaling. In a particular embodiment, the PC5 offset value is predetermined by the specification so that there is no additional SIB1 signaling.

[0118] In some embodiments, the PC5 additional time offset may have limited values ​​and signaling flexibility may be satisfied with only 1, 2, or 3 bits. As an example, some potential values ​​requiring only 1 bit could be ms20 (i.e., corresponding to 20 ms), ms50 (i.e., corresponding to 50 ms), and other values ​​requiring more bits may be added. In a particular embodiment, the PC5 additional time offset may be signaled in the ue-TimersAndConstants IE in SIB1.

[0119] 9A-9B show an example ASN.1 representation of SIB1 including UE timers and constants for the Uu interface and additional time offsets for the SL interface. In the shown example, the additional time offsets are signaled using two bits of SIB1.

[0120] 9B, the parameter Sl-AdditionalOffsetTimer-r17 uses 2 bits to indicate the value of the PC5 additional time offset from the example set {20ms, 50ms, 100ms, 200ms}. In other embodiments, the PC5 additional time offset may be signaled externally at the level of the main SIB1.

[0121] In another embodiment of the second solution, assuming that the connection timers T300, T301, T319 have values ​​of 100, 200, and 300 ms, respectively, in the received SIB1, and the PC5 additional time offset is 50 ms, the corresponding SL connection timers are as follows: ·SL-T300 = 100ms + 50ms = 150ms ·SL-T301 = 200ms + 50ms = 250ms ·SL-T319 = 300ms + 50ms = 350ms

[0122] In some embodiments, the network may calculate the time offset (PC5 additional time offset) as twice (UL and DL) the worst case time it takes for a PC5 RRC message (e.g., 80 bits) to successfully pass between the U2N sidelink remote UE 305 and its U2N sidelink relay UE 310 on the U2N sidelink, for example with around three PC5 retransmissions in each direction. The worst case needs to be defined under the specific radio conditions and channel congestion (e.g., busyness ratio) of the PC5 link and depends on the required connection establishment performance. The worst case may also depend on the resource allocation mode (mode 1 or mode 2) of the PC5 communication.

[0123] In one implementation, the sidelink U2N sidelink remote UE 305 (i.e., the U2N sidelink U2N sidelink remote UE 305) starts RRC connection timers such as T300, T301, and T319 with a given offset, e.g., signaled in the SI or fixed in the specification, as outlined above. Here, the U2N sidelink U2N sidelink remote UE 305 does not calculate new RRC timer values ​​based on the signaled offsets, but reuses the originally signaled RRC timer values. In one particular implementation, the U2N sidelink U2N sidelink remote UE 305 starts new timers with values ​​set to the time offset values ​​signaled in the SI (as shown above). When the new timer expires, the U2N sidelink remote UE 305 of the U2N sidelink starts the associated RRC timer, e.g., T300, T301, or T319, as the case may be.

[0124] FIG. 10 illustrates a sidelink relay arrangement 1000 between a U2N sidelink remote UE 305 (i.e., SL remote UE), a U2N sidelink relay UE 310, and a network (i.e., RAN node 210), and associated connection timers. A Uu connection timer 1005, such as T301, is used to manage the connection procedure on the Uu link between the RAN node 210 and the U2N sidelink relay UE 310. A "PC5 additional time" offset 1010 is needed to account for additional delay between the U2N sidelink remote UE 305 (i.e., out-of-coverage SL UE) and the U2N sidelink relay UE 310. As the original Uu connection timer 1005 is still under network configuration, the SL connection timer value used by the U2N sidelink remote UE 305 is still configurable and thus under the control of the serving RAN node 210.

[0125] According to a third solution embodiment, two values ​​are used for each of the SL connection timers instead of just one value. A first of these two values ​​is used when the U2N sidelink relay UE 310 is used in both UL and DL directions, and a second value is used when the U2N sidelink relay UE 310 is used only in one of the UL and DL directions, and the other direction uses a direct connection between the U2N sidelink remote UE 305 and the RAN node 210 of the U2N sidelink. In some embodiments, the two values ​​of the SL connection timer are signaled to the U2N sidelink remote UE 305 of the U2N sidelink in SIB1 or an additional SIB (e.g., SIB12, SIB13, SIB14, or another SIB containing information required for the operation of the U2N relay) -- as described in the first solution embodiment. In other embodiments, the two values ​​of the SL connection timer are derived from the Uu specific connection timer and the PC5 additional time offset -- as described in the second solution embodiment.

[0126] 11 illustrates a user equipment device 1100 that may be used to configure a sidelink connection timer according to an embodiment of the disclosure. In various embodiments, the user equipment device 1100 is used to implement one or more of the solutions described above. The user equipment device 1100 may be an embodiment of a user endpoint such as the remote unit 105, UE 205, U2N sidelink remote UE 305, and / or U2N sidelink relay UE 310 of the U2N sidelink described above. Additionally, the user equipment device 1100 may include a processor 1105, a memory 1110, an input device 1115, an output device 1120, and a transceiver 1125.

[0127] In some embodiments, the input devices 1115 and the output devices 1120 are combined into a single device, such as a touch screen. In certain embodiments, the user equipment device 1100 may not include any input devices 1115 and / or output devices 1120. In various embodiments, the user equipment device 1100 may include one or more of the processor 1105, the memory 1110, and the transceiver 1125, and may not include the input devices 1115 and / or the output devices 1120.

[0128] As shown, the transceiver 1125 includes at least one transmitter 1130 and at least one receiver 1135. In some embodiments, the transceiver 1125 communicates with one or more cells (or wireless coverage areas) supported by one or more base units 121. In various embodiments, the transceiver 1125 is operable in an unlicensed spectrum. Further, the transceiver 1125 may include multiple UE panels supporting one or more beams. In addition, the transceiver 1125 may support at least one network interface 1140 and / or application interface 1145. The application interface 1145 may support one or more APIs. The network interface 1140 may support 3GPP reference points such as Uu, N1, PC5, etc. As will be appreciated by one skilled in the art, other network interfaces 1140 may be supported.

[0129] The processor 1105, in one embodiment, may include any known controller capable of executing computer-readable instructions and / or performing logical operations. For example, the processor 1105 may be a microcontroller, microprocessor, central processing unit ("CPU"), graphics processing unit ("GPU"), auxiliary processing unit, field programmable gate array ("FPGA"), or similar programmable controller. In some embodiments, the processor 1105 executes instructions stored in the memory 1110 to perform the methods and routines described herein. The processor 1105 is communicatively coupled to the memory 1110, the input device 1115, the output device 1120, and the transceiver 1125.

[0130] In various embodiments, the processor 1105 controls the user equipment device 1100 to implement the UE behaviors described above. In a particular embodiment, the processor 1105 may include an application processor (also known as a “main processor”) that manages application domains and operating system (“OS”) functions, and a baseband processor (also known as a “baseband radio processor”) that manages radio functions.

[0131] In various embodiments, via the transceiver 1125, the processor 1105 receives a set of connection timers (e.g., UE-TimersAndConstants IE) from a primary system information block (e.g., SIB1) transmission of the serving node and receives a first set of sidelink connection timers (i.e., one or more sidelink connection timers) (e.g., sl-UE-TimersAndConstants or UE-TimersAndConstantsRemoteUE IE) from an additional system information block (e.g., SIB12, SIB13, SIB14, or another SIB containing information required for U2N relay operation) of the serving node.

[0132] The processor 1105 determines a second set of sidelink connection timers for establishment of communication with a network node (e.g., a gNB) using the U2N sidelink relay UE, where values ​​of each of the second set of sidelink connection timers are determined based at least in part on the first set of sidelink connection timers. Further, the processor 1105 uses the respective connection timers to manage establishment of communication with the network node via the U2N sidelink relay UE.

[0133] In some embodiments, the establishment of the managed communication includes one of an RRC connection establishment procedure, an RRC connection resumption procedure, or an RRC connection re-establishment procedure. In some embodiments, the processor 1105 starts a respective connection timer in response to transmission of an RRC connection request, an RRC resumption request, or an RRC connection re-establishment request by the transceiver 1125.

[0134] In some embodiments, the network node from which the establishment of communication is initiated includes the current serving node or a non-serving network node. In some embodiments, the second set of sidelink connection timers for the establishment of communication includes (i.e., SL specific) timers "T300", "T301" and "T319".

[0135] In some embodiments, the respective value of at least one of the second set of sidelink connection timers is determined based on a set of connection timers (e.g., included in the UE-TimersAndConstants IE) from a primary system information block (e.g., SIB1).

[0136] In some embodiments, the processor 1105 determines a value for each of the second set of sidelink connection timers by using a corresponding timer value of the first set of sidelink connection timers if included in the additional system information block, otherwise, in response to a corresponding timer value that is not in the received first set of sidelink connection timers, the processor 1105 determines the missing value by using the timer value of the equivalent Uu connection timer from the primary system information block (e.g., SIB1).

[0137] In some embodiments, the primary system information block (e.g., SIB1) includes a UE-TimersAndConstants information element indicating a set of connection timers, and the additional system information block includes a UE-TimersAndConstantsRemoteUE Set of Connection Timers information element indicating a first set of sidelink connection timers, where the additional system information block is different from the primary system information block (e.g., SIB1).

[0138] In some embodiments, the processor 1105 controls the transceiver 1125 to establish a sidelink (i.e., PC5) RRC connection with a U2N sidelink relay UE, and an SI including at least a primary system information block (e.g., SIB1) is received in a discovery message received from the U2N sidelink relay UE prior to establishment of the sidelink RRC connection.

[0139] In some embodiments, the processor 1105 controls the transceiver 1125 to establish a sidelink (i.e., PC5) RRC connection with a U2N sidelink relay UE, and SI including at least a primary system information block (e.g., SIB1) is received in an RRC reconfiguration message received from the U2N sidelink relay UE after establishment of the sidelink RRC connection.

[0140] The memory 1110, in one embodiment, is a computer-readable storage medium. In some embodiments, the memory 1110 includes a volatile computer storage medium. For example, the memory 1110 may include RAM, including dynamic RAM ("DRAM"), synchronous dynamic RAM ("SDRAM"), and / or static RAM ("SRAM"). In some embodiments, the memory 1110 includes a non-volatile computer storage medium. For example, the memory 1110 may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 1110 includes both volatile and non-volatile computer storage media.

[0141] In some embodiments, the memory 1110 stores data related to configuring the sidelink connection timer. For example, the memory 1110 may store the parameters, configurations, etc. described above. In particular embodiments, the memory 1110 also stores program code and associated data, such as an operating system or other controller algorithms running on the user equipment device 1100.

[0142] The input device 1115, in one embodiment, may include any known computer input device including a touch panel, buttons, a keyboard, a stylus, a microphone, etc. In some embodiments, the input device 1115 may be integrated with the output device 1120, for example as a touch screen or similar touch-sensitive display. In some embodiments, the input device 1115 includes a touch screen such that text may be entered using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. In some embodiments, the input device 1115 includes two or more different devices, such as a keyboard and a touch panel.

[0143] The output device 1120, in one embodiment, is designed to output visual, auditory, and / or tactile signals. In some embodiments, the output device 1120 includes an electronically controllable display or display device capable of outputting visual data to a user. For example, the output device 1120 may include, but is not limited to, a liquid crystal display ("LCD"), a light emitting diode ("LED") display, an organic LED ("OLED") display, a projector, or similar display device capable of outputting images, text, and the like to a user. As another non-limiting example, the output device 1120 may include a wearable display separate from but communicatively coupled to the remainder of the user equipment device 1100, such as a smart watch, smart glasses, a head-up display, and the like. Additionally, the output device 1120 may be a component of a smartphone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, and the like.

[0144] In certain embodiments, the output device(s) 1120 include one or more speakers for generating sound. For example, the output device(s) 1120 may generate an audible alert or notification (e.g., a beep or chime). In some embodiments, the output device(s) 1120 include one or more haptic devices for generating vibration, movement, or other haptic feedback. In some embodiments, all or a portion of the output device(s) 1120 may be integrated with the input device(s) 1115. For example, the input device(s) 1115 and the output device(s) 1120 may form a touchscreen or similar touch-sensitive display. In other embodiments, the output device(s) 1120 may be located near the input device(s) 1115.

[0145] The transceiver 1125 communicates with one or more network functions of a mobile communications network via one or more access networks. The transceiver 1125 operates under the control of the processor 1105 to transmit messages, data, and other signals and to receive messages, data, and other signals. For example, the processor 1105 may selectively activate the transceiver 1125 (or a portion thereof) at a particular time to transmit and receive messages.

[0146] The transceiver 1125 includes at least one transmitter 1130 and at least one receiver 1135. The one or more transmitters 1130 may be used to provide UL communication signals to the base unit 121, such as the UL transmissions described herein. Similarly, the one or more receivers 1135 may be used to receive DL communication signals from the base unit 121, as described herein. Although only one transmitter 1130 and one receiver 1135 are shown, the user equipment device 1100 may have any suitable number of transmitters 1130 and receivers 1135. Furthermore, the transmitters 1130 and receivers 1135 may be any suitable type of transmitter and receiver. In one embodiment, the transceiver 1125 includes a first transmitter / receiver pair used to communicate with a mobile communications network over a licensed radio spectrum and a second transmitter / receiver pair used to communicate with a mobile communications network over an unlicensed radio spectrum.

[0147] In certain embodiments, a first transmitter / receiver pair used to communicate with a mobile communications network over a licensed radio spectrum and a second transmitter / receiver pair used to communicate with a mobile communications network over an unlicensed radio spectrum may be combined into a single transceiver unit, e.g., a single chip that performs functions for use in both the licensed and unlicensed radio spectrum. In some embodiments, the first transmitter / receiver pair and the second transmitter / receiver pair may share one or more hardware components. For example, a particular transceiver 1125, transmitter 1130, and receiver 1135 may be implemented as physically separate components that access shared hardware and / or software resources, such as, for example, a network interface 1140.

[0148] In various embodiments, one or more transmitters 1130 and / or one or more receivers 1135 may be implemented and / or integrated in a single hardware component, such as a multi-transceiver chip, a system on a chip, an application specific integrated circuit ("ASIC"), or other type of hardware component. In particular embodiments, one or more transmitters 1130 and / or one or more receivers 1135 may be implemented and / or integrated in a multi-chip module. In some embodiments, other components, such as a network interface 1140 or other hardware components / circuits, may be integrated in a single chip with any number of transmitters 1130 and / or receivers 1135. In such embodiments, the transmitters 1130 and receivers 1135 may be logically configured as a transceiver 1125 using one or more common control signals, or as modular transmitters 1130 and receivers 1135 implemented in the same hardware chip or multi-chip module.

[0149] 12 illustrates a network device 1200 that may be used to configure a sidelink connection timer according to an embodiment of the disclosure. In one embodiment, the network device 1200 may be an implementation of one of the network endpoints, such as the base unit 121 and / or the RAN node 210 described above. Additionally, the network device 1200 may include a processor 1205, a memory 1210, an input device 1215, an output device 1220, and a transceiver 1225.

[0150] In some embodiments, the input device(s) 1215 and the output device(s) 1220 are combined into a single device, such as a touch screen. In certain embodiments, the network device 1200 may not include any input device(s) 1215 and / or output device(s) 1220. In various embodiments, the network device 1200 may include one or more of the processor 1205, the memory 1210, and the transceiver 1225, and may not include the input device(s) 1215 and / or the output device(s) 1220.

[0151] As shown, the transceiver 1225 includes at least one transmitter 1230 and at least one receiver 1235, where the transceiver 1225 communicates with one or more remote units 105. In addition, the transceiver 1225 may support at least one network interface 1240 and / or application interface 1245. The application interface 1245 may support one or more APIs. The network interface 1240 may support 3GPP reference points such as Uu, N1, N2, and N3. As will be appreciated by one skilled in the art, other network interfaces 1240 may be supported.

[0152] The processor 1205, in one embodiment, may include any known controller capable of executing computer-readable instructions and / or performing logical operations. For example, the processor 1205 may be a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, or a similar programmable controller. In some embodiments, the processor 1205 executes instructions stored in the memory 1210 to perform the methods and routines described herein. The processor 1205 is communicatively coupled to the memory 1210, the input device 1215, the output device 1220, and the transceiver 1225.

[0153] In various embodiments, the network device 1200 is a RAN node (e.g., gNB) that communicates with one or more UEs as described herein. In such embodiments, the processor 1205 controls the network device 1200 to perform the RAN behavior described above. When operating as a RAN node, the processor 1205 may include an application processor (also known as a “main processor”) that manages application domains and operating system (“OS”) functions, and a baseband processor (also known as a “baseband radio processor”) that manages radio functions.

[0154] In various embodiments, the processor 1205 determines a set of SL-specific connection timers and transmits information of the set of SL-specific connection timers to the at least one UE via the transceiver 1225. For example, the apparatus 1200 may transmit Uu-specific connection timers in SIB1 and further transmit SL-specific connection timers in an additional SIB. As another example, the apparatus 1200 may broadcast a time offset for use in deriving the SL-specific connection timers from the Uu-specific connection timers.

[0155] In some embodiments, the time offset comprises a time value expressed in milliseconds used to manage an RRC connection establishment procedure by a remote UE in sidelink communications. In some embodiments, the time offset comprises a time value expressed in milliseconds used to manage an RRC connection resumption procedure by a remote UE in sidelink communications. In some embodiments, the time offset comprises a time value expressed in milliseconds used to manage an RRC connection re-establishment procedure by a remote UE in sidelink communications.

[0156] Memory 1210, in one embodiment, is a computer-readable storage medium. In some embodiments, memory 1210 includes a volatile computer storage medium. For example, memory 1210 may include RAM, including DRAM, SDRAM, and / or SRAM. In some embodiments, memory 1210 includes a non-volatile computer storage medium. For example, memory 1210 may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, memory 1210 includes both volatile and non-volatile computer storage media.

[0157] In some embodiments, the memory 1210 stores data related to configuring the sidelink connection timer. For example, the memory 1210 may store the parameters, configurations, etc. described above. In particular embodiments, the memory 1210 also stores program code and associated data, such as an operating system or other controller algorithms running on the network device 1200.

[0158] The input device 1215, in one embodiment, may include any known computer input device including a touch panel, buttons, a keyboard, a stylus, a microphone, etc. In some embodiments, the input device 1215 may be integrated with the output device 1220, for example as a touch screen or similar touch-sensitive display. In some embodiments, the input device 1215 includes a touch screen such that text may be entered using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. In some embodiments, the input device 1215 includes two or more different devices, such as a keyboard and a touch panel.

[0159] The output device 1220, in one embodiment, is designed to output visual, auditory, and / or tactile signals. In some embodiments, the output device 1220 includes an electronically controllable display or display device capable of outputting visual data to a user. For example, the output device 1220 may include, but is not limited to, an LCD display, an LED display, an OLED display, a projector, or similar display device capable of outputting images, text, and the like to a user. As another non-limiting example, the output device 1220 may include a wearable display separate from but communicatively coupled to the rest of the network device 1200, such as a smart watch, smart glasses, a head-up display, and the like. Additionally, the output device 1220 may be a component of a smartphone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, and the like.

[0160] In certain embodiments, the output device(s) 1220 include one or more speakers for generating sound. For example, the output device(s) 1220 may generate an audible alert or notification (e.g., a beep or chime). In some embodiments, the output device(s) 1220 include one or more haptic devices for generating vibration, movement, or other haptic feedback. In some embodiments, all or a portion of the output device(s) 1220 may be integrated with the input device(s) 1215. For example, the input device(s) 1215 and the output device(s) 1220 may form a touchscreen or similar touch-sensitive display. In other embodiments, the output device(s) 1220 may be located near the input device(s) 1215.

[0161] The transceiver 1225 includes at least one transmitter 1230 and at least one receiver 1235. The one or more transmitters 1230 may be used to communicate with a UE as described herein. Similarly, the one or more receivers 1235 may be used to communicate with a network function of a PLMN and / or a RAN as described herein. Although only one transmitter 1230 and one receiver 1235 are shown, the network device 1200 may have any suitable number of transmitters 1230 and receivers 1235. Furthermore, the transmitters 1230 and receivers 1235 may be any suitable type of transmitter and receiver.

[0162] 13 illustrates one embodiment of a method 1300 for configuring a sidelink connection timer in accordance with an embodiment of the disclosure. In various embodiments, the method 1300 is performed by a communications device, such as the remote unit 105, UE 205, and / or user equipment device 1100 described above. In some embodiments, the method 1300 is performed by a processor, such as a microcontroller, microprocessor, CPU, GPU, auxiliary processing unit, FPGA, etc.

[0163] The method 1300 includes receiving 1305 a set of connection timers (e.g., UE-TimersAndConstants IE) from a first system information block (i.e., SIB1) transmission of the serving node. The method 1300 includes receiving 1310 a first set of sidelink connection timers (i.e., one or more sidelink connection timers) from an additional system information block (e.g., sl-UE-TimersAndConstants IE) of the serving node. The method 1300 includes determining 1315 a second set of sidelink connection timers for establishment of communication with the network node using the UE inter-network sidelink relay UE, where a respective value of each timer of the second set of sidelink connection timers is determined based at least in part on the first set of sidelink connection timers. The method 1300 includes using 1320 the respective connection timers to manage establishment of communication with the network node via the U2N sidelink relay UE.

[0164] Disclosed herein is a first apparatus for configuring a sidelink connection timer according to an embodiment of the present disclosure. The first apparatus may be implemented by a communication device such as the remote unit 105, the UE 205, the U2N sidelink remote UE 305 of the U2N sidelink, and / or the user equipment device 1100 described above. The first apparatus includes a processor coupled to a memory, wherein the processor is configured to cause the apparatus to A) receive a set of connection timers (e.g., UE-TimersAndConstants IE) from a first system information block (i.e., SIB1) transmission of a serving node; B) receive a first set of sidelink connection timers (i.e., one or more sidelink connection timers) from an additional system information block (e.g., sl-UE-TimersAndConstants or UE-TimersAndConstantsRemoteUE IE) of the serving node; C) determine a second set of sidelink connection timers for establishment of communication with a network node using a U2N sidelink relay UE, wherein values ​​of each of the second set of sidelink connection timers are determined based at least in part on the first set of sidelink connection timers; and D) use the respective connection timers for managing establishment of communication with the network node via the U2N sidelink relay UE.

[0165] In some embodiments, the establishment of the managed communication includes one of an RRC connection establishment procedure, an RRC connection resumption procedure, or an RRC connection re-establishment procedure. In some embodiments, the processor is configured to cause the device to start a respective connection timer in response to transmitting the RRC connection request, the RRC resumption request, or the RRC connection re-establishment request.

[0166] In some embodiments, the network node from which the establishment of communication is initiated includes the current serving node or a non-serving network node. In some embodiments, the second set of sidelink connection timers for the establishment of communication includes (i.e., SL specific) timers "T300", "T301" and "T319".

[0167] In some embodiments, the respective value of at least one of the second set of sidelink connection timers is determined based on the set of connection timers (e.g., included in the UE-TimersAndConstants IE) from the first system information block (i.e., SIB1).

[0168] In some embodiments, the processor is configured to cause the apparatus to determine a value for each of the second set of sidelink connection timers by using a corresponding timer value of the first set of sidelink connection timers if included in the additional system information block, or by using a timer value of an equivalent Uu connection timer from the first system information block otherwise (e.g. in response to a corresponding timer value not being present in the received first set of sidelink connection timers).

[0169] In some embodiments, the first system information block (i.e., SIB1) includes a UE-TimersAndConstants information element indicating a set of connection timers, and the additional system information block includes a UE-TimersAndConstantsRemoteUE Set of Connection Timers information element indicating the first set of sidelink connection timers, where the additional system information block is different from the first system information block (i.e., SIB1).

[0170] In some embodiments, the processor is configured to cause the apparatus to establish a sidelink (i.e., PC5) RRC connection with a U2N sidelink relay UE, and an SI including at least a first system information block (i.e., SIB1) is received in a discovery message received from the U2N sidelink relay UE prior to establishment of the sidelink RRC connection.

[0171] In some embodiments, the processor is configured to cause the apparatus to establish a sidelink (i.e., PC5) RRC connection with a U2N sidelink relay UE, and an SI including at least a first system information block (i.e., SIB1) is received in an RRC reconfiguration message received from the U2N sidelink relay UE after establishment of the sidelink RRC connection.

[0172] Disclosed herein is a first method for configuring sidelink connection timers according to an embodiment of the present disclosure. The first method may be performed by a communication device, such as the remote unit 105, UE 205, U2N sidelink remote UE 305 of the U2N sidelink, and / or user equipment device 1100 described above. The first method includes receiving a set of connection timers (e.g., UE-TimersAndConstants IE) from a first system information block (i.e., SIB1) transmission of the serving node and receiving a first set of sidelink connection timers (i.e., one or more sidelink connection timers) (e.g., sl-UE-TimersAndConstants IE) from an additional system information block (i.e., sl-UE-TimersAndConstants IE) of the serving node. The first method includes determining a second set of sidelink connection timers for establishment of communication with a network node using a UE inter-network sidelink relay UE, where a respective value of each timer of the second set of sidelink connection timers is determined based at least in part on the first set of sidelink connection timers. The first method includes using a respective connection timer to manage the establishment of communications with a network node via a U2N sidelink relay UE.

[0173] In some embodiments, the establishment of the managed communication includes one of an RRC connection establishment procedure, an RRC connection resume procedure, or an RRC connection re-establishment procedure. In some embodiments, the first method includes starting a respective connection timer in response to transmitting an RRC connection request, an RRC resume request, or an RRC connection re-establishment request.

[0174] In some embodiments, the network node from which the establishment of communication is initiated includes the current serving node or a non-serving network node. In some embodiments, the second set of sidelink connection timers for the establishment of communication includes (e.g., SL specific) timers "T300", "T301" and "T319".

[0175] In some embodiments, the respective value of at least one of the second set of sidelink connection timers is determined based on the set of connection timers (e.g., included in the UE-TimersAndConstants IE) from the first system information block (i.e., SIB1).

[0176] In some embodiments, the first method comprises determining a value for each of a second set of sidelink connection timers by using a corresponding timer value of the first set of sidelink connection timers if included in the additional system information block, or by using a timer value of an equivalent Uu connection timer from the first system information block otherwise (e.g. in response to a corresponding timer value not being present in the received first set of sidelink connection timers).

[0177] In some embodiments, the first system information block (i.e., SIB1) includes a UE-TimersAndConstants IE indicating a set of connection timers, and the additional system information block includes a Set of Connection Timers (i.e., sl-UE-TimersAndConstants or UE-TimersAndConstantsRemoteUE) information element indicating the first set of sidelink connection timers, and the additional system information block is different from the first system information block (i.e., SIB1).

[0178] In some embodiments, the first method includes establishing a sidelink (i.e., PC5) RRC connection with a U2N sidelink relay UE, where an SI including at least a first system information block (i.e., SIB1) is received in a discovery message received from the U2N sidelink relay UE prior to establishment of the sidelink RRC connection.

[0179] In some embodiments, the first method includes establishing a sidelink (i.e., PC5) RRC connection with a U2N sidelink relay UE, where an SI including at least a first system information block (i.e., SIB1) is received in an RRC reconfiguration message received from the U2N sidelink relay UE after establishment of the sidelink RRC connection.

[0180] The embodiments may be embodied in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is therefore indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope. [Explanation of symbols]

[0181] 100 Wireless communication system 105 Remote Unit 107 Applications 115 Sidelink Communication Link 120 Radio Access Network ("RAN") 121 Base Unit 123 Wireless Communication Links 140 Mobile Core Network 141 User Plane Function (UPF) 143 Access and Mobility Management Function (AMF) 145 Session Management Facility (SMF) 147 Policy Control Function (PCF) 149 UDM / UDR 150 Packet Data Network 151 Application Server 200 NR Protocol Stack 201 User Plane Protocol Stack 203 Control Plane Protocol Stack 205 UE 210 RAN nodes 215 AMF 220 Physical (PHY) Layer 225 MAC Sublayer 230 Radio Link Control (RLC) Sublayer 235 PDCP Sublayer 240 Service Data Adaptation Protocol (SDAP) Sublayer 245 Radio Resource Control (RRC) Layer 250 Non-Access Layer (NAS) Layer 255 Access Layer (AS) 260 AS Layer 300 Steps 305 U2N Sidelink Remote UE 310 U2N Side Link Relay UE 400 Steps 500 steps 600 steps 1000 Side link relay arrangement 1005 Uu connection timer 1010 "PC5 additional time" offset 1100 User equipment device 1105 Processor 1110 Memory 1115 Input Devices 1120 Output Device 1125 Transceiver 1130 Transmitter 1135 Receiver 1140 Network Interface 1145 Application Interface 1200 Network Equipment 1205 Processor 1210 Memory 1215 Input Devices 1220 output device 1225 Transceiver 1230 Transmitter 1235 Receiver 1240 Network Interface 1245 Application Interface 1300 methods

Claims

1. A user equipment ("UE") for wireless communication, comprising: Memory, a processor coupled to the memory, the processor causing the UE to: receiving a first system information block (SIB) indicating a set of connection timers; receiving an additional SIB indicating a first set of sidelink connection timers; determining a second set of sidelink connection timers for establishment of communication with the network node via the sidelink relay UE, determining, wherein respective values ​​of the second set of sidelink connection timers are determined based at least in part on the first set of sidelink connection timers; and A user equipment ("UE") configured to cause use of a respective connection timer to manage establishment of communication with the network node via the sidelink relay UE.

2. 10. The UE of claim 1, wherein the establishment of the managed communication includes one of a Radio Resource Control ("RRC") connection establishment procedure, an RRC connection resumption procedure, or an RRC connection re-establishment procedure.

3. 10. The UE of claim 1, wherein the processor is configured to cause the UE to start the respective connection timer in response to transmitting a radio resource control ("RRC") connection request, an RRC resumption request, or an RRC connection re-establishment request.

4. The UE of claim 1 , wherein the network node through which the communication establishment is initiated comprises a current serving node or a non-serving network node.

5. 2. The UE of claim 1, wherein a respective value of at least one of the second set of sidelink connection timers is determined based on the set of connection timers from the first system information block.

6. 2. The UE of claim 1, wherein the processor is configured to cause the UE to determine the respective values ​​of the second set of sidelink connection timers by using a corresponding timer value of the first set of sidelink connection timers if included in the additional system information block, and by using a timer value of an equivalent Uu connection timer from the first system information block otherwise.

7. 2. The UE of claim 1 , wherein the first system information block includes a UE-TimersAndConstants information element indicating the set of connection timers, and the additional system information block includes a UE-TimersAndConstantsRemoteUE Set of Connection Timers information element indicating the first set of sidelink connection timers, the additional system information block being different from the first system information block.

8. 2. The UE of claim 1, wherein the processor is configured to cause the UE to establish a sidelink radio resource control ("RRC") connection with the sidelink relay UE, and system information including at least the first system information block is received in a discovery message received from the sidelink relay UE prior to establishment of the sidelink RRC connection.

9. 2. The UE of claim 1, wherein the processor is configured to cause the UE to establish a sidelink radio resource control ("RRC") connection with the sidelink relay UE, and wherein system information including at least the first system information block is received in an RRC reconfiguration message received from the sidelink relay UE after establishment of the sidelink RRC connection.

10. A method for wireless communication executable by a user equipment ("UE"), receiving a first system information block (SIB) indicating a set of connection timers; receiving an additional SIB indicating a first set of sidelink connection timers; determining a second set of sidelink connection timers for establishment of communication with the network node via the sidelink relay UE, determining a respective value for each timer of the second set of sidelink connection timers based at least in part on the first set of sidelink connection timers; using a respective connection timer to manage the establishment of communication with the network node via the sidelink relay UE; A method comprising:

11. 11. The method of claim 10, wherein the establishment of the managed communication includes one of a Radio Resource Control ("RRC") connection establishment procedure, an RRC connection resumption procedure, or an RRC connection re-establishment procedure.

12. 11. The method of claim 10, further comprising starting the respective connection timer in response to transmitting a radio resource control ("RRC") connection request, an RRC resumption request, or an RRC connection re-establishment request.

13. 11. The method of claim 10, wherein a respective value of at least one of the second set of sidelink connection timers is determined based on the set of connection timers from the first SIB, and wherein the second set of sidelink connection timers for establishment of a communication includes timers “T300”, “T301”, and “T319”.

14. 11. The method of claim 10, further comprising determining the respective values ​​of the second set of sidelink connection timers by using a corresponding timer value of the first set of sidelink connection timers if included in the additional SIB, or by using a timer value of an equivalent Uu connection timer from the first SIB otherwise.

15. A network device for wireless communication, comprising: Memory, a processor coupled to the memory, the processor transmitting to the network device: transmitting a first system information block (SIB) indicating a set of connection timers; and and causing the transmission of an additional SIB indicating a first set of sidelink connection timers. Network device.

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