Relay announcements for sidelink operations

Abstract

Apparatus, methods, and systems for relay announcements for sidelink operation are disclosed. One apparatus includes a processor and a transceiver that receives a relay announcement from a sidelink-enabled relay UE (SL), wherein the relay announcement includes at least one relay attribute. The processor uses the at least one relay attribute to determine a relay required via the SL UE. The transceiver sends a relay connection request to the SL UE and receives a relay connection confirmation from the SL UE. Via the transceiver, the processor performs sidelink communication with a remote receiver device via the SL UE.

Description

[0001] Cross-reference to related applications

[0002] This application claims U.S. Patent Application Serial No. 63 / 061,715, filed August 5, 2020, by Joachim Loehr, Prateek Basu Mallick, Karthikeyan Ganesan, and Ravi Kuchibhotla, entitled "Apparatus, Methods, and Systems for a Sidelink Resource Allocation Process for Sidelink Relay Communication"; and U.S. Patent Application Serial No. 63 / 061,715, filed August 5, 2020, by Prateek Basu Mallick, Joachim Loehr, Ravi Kuchibhotla, and Karthikeyan Ganesan, entitled "Mechanisms for Improved Communications Using Relay Over Sidelink Radio". U.S. Patent Application Serial No. 63 / 061,725, entitled “INTERFACE (Mechanism for Improving Communications Using Relays via Sidelink Radio Interfaces)”; U.S. Patent Application Serial No. 63 / 061,731, entitled “SELECTION OF RELAY DEVICE IN SIDELINK COMMUNICATIONS”, filed August 5, 2020, by Prateek Basu Mallick, Joachim Loehr, Joachim Loehr, and Ravi Kuchibhotla; and U.S. Patent Application Serial No. 63 / 061,734, entitled “MECHANISMS TO SUPPORT TRANSMISSION FEEDBACK OVER SIDELINK RELAY”, filed August 5, 2020, by Prateek Basu Mallick, Joachim Loehr, Joachim Loehr, and Ravi Kuchibhotla.The entire contents of this patent application, U.S. Patent Application Serial No. 63 / 061,746, filed August 5, 2020, entitled “Apparatus, Methods, and Systems for Determining the Behaviour of a Sidelink Relay UE Using MCR and Zone,” are incorporated herein by reference. Technical Field

[0003] The topics disclosed herein generally relate to wireless communication, and more specifically to relay announcements for selecting relay devices in sidelink communication. Background Technology

[0004] Sidelink (“SL”) relay is a potential means of increasing coverage using one or more hops. For UE-to-network coverage extension, Uu coverage reachability is necessary for the UE to reach a server in the packet data network (“PDN”) or a peer user equipment (“UE”) outside the vicinity. For UE-to-UE coverage extension, current proximity reachability is limited to single-hop sidelinks, or via sidelink technologies based on Evolved Universal Terrestrial Radio Access (“EUTRA”) or NR. Summary of the Invention

[0005] A process for relay notification for sidelink operation is disclosed. This process can be implemented by an apparatus, system, method, or computer program product.

[0006] A method for transmitting a relay advertisement for sidelink operation by a transmitting remote user equipment (“Tx Remote UE”) includes receiving a relay advertisement from a relay user equipment (“UE”) device supporting sidelink (“SL”) operation, wherein the relay advertisement contains at least one relay attribute, and using the at least one relay attribute to determine a relay that needs to be relayed via the SL Relay UE. The method includes sending a relay connection request to the SL Relay UE, receiving a relay connection confirmation from the SL Relay UE, and performing SL communication with a remote receiver device via the SL Relay UE.

[0007] A method for a sidelink relay user equipment (“SL relay UE”) for relay announcements for sidelink operation includes transmitting a relay announcement from the SL relay UE supporting SL operation and receiving a relay connection request from a remote transmitter device, wherein the relay announcement includes at least one relay attribute, and wherein the remote transmitter device uses the at least one relay attribute to select the SL relay UE. The method includes transmitting a relay connection acknowledgment to the remote transmitter device and relaying SL communication between the remote transmitter device and a remote receiver device. Attached Figure Description

[0008] A more specific description of the embodiments briefly described above will be presented with reference to specific embodiments illustrated in the accompanying drawings. It should be understood that these drawings depict only a few embodiments and should therefore not be considered as limiting the scope; the embodiments will be described and explained with additional specificity and detail using the drawings, in which:

[0009] Figure 1 This is a schematic block diagram illustrating one embodiment of a wireless communication system for relay announcements for sidelink operations.

[0010] Figure 2A This is a block diagram illustrating one embodiment of a relay arrangement for transmitting a transport block (“TB”) via unicast transmission;

[0011] Figure 2B This is a block diagram illustrating one embodiment of a sidelink (e.g., PC5) protocol stack;

[0012] Figure 3 This is a block diagram illustrating one embodiment of the process of selecting a relay device;

[0013] Figure 4 This is a block diagram illustrating one embodiment of the 5G New Radio (“NR”) protocol stack;

[0014] Figure 5 This is a block diagram illustrating one embodiment of a user equipment device that can be used for relay announcements for sidelink operations;

[0015] Figure 6 This is a block diagram illustrating one embodiment of a network device apparatus that can be used for relay announcements for sidelink operations;

[0016] Figure 7 This is a block diagram illustrating an embodiment of a first method for relay notification for sidelink operations; and

[0017] Figure 8 This is a block diagram illustrating an embodiment of a second method for relay notification for sidelink operations. Detailed Implementation

[0018] As those skilled in the art will understand, aspects of the embodiments can be embodied as a system, apparatus, method, or program product. Therefore, embodiments can take the form of a completely hardware embodiment, a completely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining aspects of both software and hardware.

[0019] For example, the disclosed embodiments can be implemented as hardware circuitry that includes custom-designed very large-scale integration (“VLSI”) circuitry or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. The disclosed embodiments can 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, for example, be organized as objects, procedures, or functions.

[0020] Furthermore, embodiments may take the form of a program product embodied in one or more computer-readable storage devices that store machine-readable code, computer-readable code, and / or program code, hereinafter referred to as code. The storage device may be tangible, non-transitory, and / or non-transferable. The storage device may not embody signals. In one embodiment, the storage device employs only signals for accessing the code.

[0021] Any combination of one or more computer-readable media may be used. A computer-readable medium may be a computer-readable storage medium. A computer-readable storage medium may be a storage device for storing code. A storage device may be, for example, but not limited to, electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor systems, apparatuses, or devices, or any suitable combination thereof.

[0022] More specific examples of storage devices (a non-exhaustive list) will include the following: electrical connections having one or more wires, portable computer floppy disks, hard disks, random access memory (“RAM”), read-only memory (“ROM”), erasable programmable read-only memory (“EPROM” or flash memory), portable compact disc read-only memory (“CD-ROM”), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium can be any tangible medium capable of containing or storing a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0023] The code used to perform the operations of the embodiments can be any number of lines and can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Python, Ruby, Java, Smalltalk, and C++, and traditional procedural programming languages ​​such as the "C" programming language, and / or machine languages ​​such as assembly language. The code can be executed 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 latter scenario, the remote computer can be connected to the user's computer via any type of network, including a local area network ("LAN") or a wide area network ("WAN"), or can be connected to an external computer (e.g., via the Internet provided by an Internet service provider).

[0024] Furthermore, the features, structures, or characteristics described in the embodiments can be combined in any suitable manner. Numerous specific details, such as examples of programming, software modules, user selection, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., are provided in the following description to provide a thorough understanding of the embodiments. However, those skilled in the art will recognize that the embodiments can be practiced without one or more of these specific details or using other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the embodiments.

[0025] Throughout this specification, references to "an embodiment," "embodiment," or similar language mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Therefore, unless expressly stated otherwise, the phrases "in an embodiment," "in an embodiment," and similar language throughout this specification may, but do not necessarily, refer to the same embodiment, but rather mean "one or more, but not all, embodiments." Unless expressly stated otherwise, the terms "comprising," "including," "having," and variations thereof mean "including, but not limited to,". Unless expressly stated otherwise, the list of enumerated items does not imply that any or all items are mutually exclusive. Unless expressly stated otherwise, the terms "a / an" and "the" also mean "one or more".

[0026] As used herein, a list containing 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 one and 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 combinations of A, B, and C. As used herein, “selected from the group consisting of A, B, and C” includes one and only one of A, B, or C and excludes combinations of A, B, and C. As used in this article, “selecting members of a group consisting of A, B, and C and their combinations” includes only A, only B, only C, combinations of A and B, combinations of B and C, combinations of A and C, or combinations of A, B, and C.

[0027] The following description of various aspects of the embodiments is based on schematic flowcharts and / or block diagrams of methods, apparatus, systems, and program products according to the embodiments. It will be understood that individual blocks in the schematic flowcharts and / or block diagrams, as well as combinations of blocks in the schematic flowcharts and / or block diagrams, can be implemented by code. This code can be provided to a processor of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus to produce a machine such that instructions executable via the processor of the computer or other programmable data processing apparatus create means for implementing the functions / actions specified in the flowcharts and / or block diagrams.

[0028] The code can also be stored in a storage device that can instruct a computer, other programmable data processing device or other device to operate in a particular manner, such that the instructions stored in the storage device produce an article of art including instructions that implement the functions / actions specified in the flowchart and / or block diagram.

[0029] The code may also be loaded onto a computer, other programmable data processing apparatus or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device, thereby producing a computer-implemented process, such that the code executing on the computer or other programmable apparatus provides a process for implementing the functions / actions specified in the flowchart and / or block diagram.

[0030] The flowcharts and / or block diagrams in the accompanying drawings 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 flowcharts and / or block diagrams may represent a module, segment, or portion of code, which includes one or more executable instructions for implementing specified logical functions(s).

[0031] It should also be noted that in some alternative implementations, the functions marked in the boxes may not appear in the order shown in the figures. For example, two boxes shown consecutively may actually be executed substantially simultaneously, or these boxes may sometimes be executed in reverse order, depending on the functionality involved. Other steps and methods that are equivalent in function, logic, or effect to one or more boxes or portions thereof shown in the figures can be contemplated.

[0032] While various arrow and line types may be used in flowcharts and / or block diagrams, they are not intended to limit the scope of the corresponding embodiments. In practice, some arrows or other connectors may be used only to indicate the logical flow of the depicted embodiment. For example, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of a depicted embodiment. It will also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented by a system based on dedicated hardware or a combination of dedicated hardware and code that performs the specified function or action.

[0033] The description of the elements in each figure can be referenced to the elements in the preceding figures. In all figures, similar reference numerals refer to similar elements, including alternative embodiments of similar elements.

[0034] Generally, this disclosure describes systems, methods, and apparatuses for mechanisms of selecting relay devices for sidelink operation from relay announcements. In some embodiments, methods may be performed using computer code embedded in a computer-readable medium. In some embodiments, an apparatus or system may include a computer-readable medium containing computer-readable code that, when executed by a processor, causes the apparatus or system to perform at least a portion of a solution.

[0035] As mentioned above, this paper considers two types of relays:

[0036] 1) UE to Network Relay (also known as “N-Relay”): Uu coverage reachability is necessary for a UE to reach a server in a Packet Data Network (“PDN”) or a peer UE outside the proximity area. However, the N-Relay solution previously defined in 3GPP Rel-13 is limited to EUTRA-based technologies and therefore cannot be applied to NR-based systems for both next-generation (i.e., 5G) radio access networks (“NG-RAN”) and NR-based sidelink communication.

[0037] 2) UE-to-UE relay (also known as "UE relay"): Currently, proximity reachability is limited to single-hop sidelinks via EUTRA-based or NR-based sidelink technologies. However, given the limited coverage of single-hop sidelinks, this is insufficient in scenarios without Uu coverage (i.e., the UE is outside RAN coverage).

[0038] For both sidelink (“SL”) relay types, the SL remote UE needs to discover and select the relay for transmitting to the SL remote. This document describes the mechanism for defining the criteria used to select the SL relay UE. This document also describes the mechanism for defining when a transmitter (“Tx”) SL remote UE (also referred to as a “Tx remote UE”) begins transmitting data through the selected SL relay UE and when the Tx SL remote UE stops transmitting data through the selected SL relay UE.

[0039] Multiple relays for NR sidelinks are a new area of ​​research. In previous systems like Evolved Universal Terrestrial Radio Access (“EUTRA”), there was no relevant concept of using Hybrid Automatic Repeat Request (“HARQ”) feedback, and therefore no direct conventional solution for relay scenarios that use relays to increase reliability and / or coverage.

[0040] This disclosure describes numerous new attributes and other criteria that can be announced by the relay, helping a Tx remote UE (also referred to herein as "UE1") determine whether it should select a given relay. Additionally, new triggers are defined when a remote UE can begin relaying data to another remote UE via a relay UE and when a remote UE can stop relaying data via a relay UE. Furthermore, two distinct Tx-remote UE behaviors are defined during relay (re)selection when a particular TB may still be in transmission on a previous link (Uu, direct link, or using a previous relay).

[0041] There is no prior solution in NR systems where relays are used in sidelinks to increase reliability. There is also no prior solution in 3GPP for sidelink communication using relays that utilize retransmissions based on sidelink HARQ feedback. An SL relay UE (also referred to herein as "UE2") can be used to reach an Rx remote UE (also referred to herein as "UE3"); however, UE behavior when a remote UE selects a relay UE is not yet available, assuming the characteristics of SL HARQ feedback, MCR, and 3-broadcast type. Because relays are used to reach remote receiver UEs that may otherwise be outside the communication range of the remote transmitter, the solution disclosed herein not only increases transmission reliability but also coverage.

[0042] In one embodiment, several trigger points are disclosed. Remote UE1 uses the following triggers to begin searching for a relay:

[0043] For UC (unicast) transmission from UE1 to UE3

[0044] After “n1” unsuccessful attempts to reach the unicast (“UC”) destination (i.e., UE3) directly.

[0045] When the UC destination (i.e., UE3) is reachable but the link conditions are unsatisfactory

[0046] For multicast (“GC”) direct transmission from UE1 to UE3 (and other receiver UEs)

[0047] When using SL HARQ feedback option 2 and missing "n2" acknowledgments (not received at UE1)

[0048] When using SL HARQ feedback option 2 and receiving "n3" NACKs

[0049] When using SL HARQ feedback option 2 and the sum of received NACKs and lost feedback (i.e., DTX from the receiver UE) exceeds “n4”

[0050] When using SL HARQ feedback option 1 and receiving "n5" NACKs

[0051] When UE1 cannot access its location

[0052] According to SL HARQ feedback option 1 (i.e., NACK-only indication sent using common feedback resources), all receivers(s) that fail to decode a received SL data packet will send a HARQNACK on resources common to all receivers. HARQ NACK feedback is provided via the system frame number (“SFN”) combined over the air.

[0053] According to SL HARQ feedback option 2 (i.e., Rx UE-specific ACK or NACK indication sent using dedicated feedback resources), each receiver that receives the physical sidelink control channel (“PSCCH”) (e.g., containing sidelink control information (“SCI”)) and attempts to decode the corresponding physical sidelink shared channel (“PSSCH”) (e.g., containing SL data) will respond with HARQ-ACK in the corresponding resource depending on whether they successfully decode the data packet.

[0054] As used herein, “HARQ-ACK” can collectively represent a positive acknowledgment (“ACK”) indication, a negative acknowledgment (“NACK”) indication, and a discontinuous transmission (“DTX”) indication. Signaling ACK indicates that a transport block (“TB”, also known as a data packet) has been correctly received, signaling NACK (or NAK) indicates that a TB has been incorrectly received (e.g., received but not successfully decoded), and signaling DTX indicates that a TB was not detected.

[0055] Figure 1 A wireless communication system 100 for relay notification for sidelink operation according to embodiments of the present disclosure is depicted. 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 constituted by a base station unit 121, and the remote unit 105 communicates with the base station unit 121 using a wireless communication link 123. Although in Figure 1 The document depicts a specific number of remote units 105, base station units 121, wireless communication links 123, RAN 120, and mobile core network 140, but those skilled in the art will recognize that any number of remote units 105, base station units 121, wireless communication links 123, RAN 120, and mobile core network 140 can be included in the wireless communication system 100.

[0056] In one implementation, RAN 120 conforms to the 5G system specifications outlined in the 3rd Generation Partnership Project (“3GPP”). For example, RAN 120 may be a next-generation radio access network (“NG-RAN”) implementing a new radio (“NR”) radio access technology (“RAT”) and / or a long-term evolution (“LTE”) RAT. In another example, RAN 120 may include non-3GPP RAT (e.g., Or an IEEE 802.11 series compliant WLAN. In another embodiment, RAN 120 conforms to the LTE system specified in the 3GPP specification. However, more generally, the wireless communication system 100 can implement some other open or proprietary communication networks, such as Global Microwave Access Interoperability (“WiMAX”) or the IEEE 802.16 series standards, as well as other networks. This disclosure is not intended to limit implementation to any particular wireless communication system architecture or protocol.

[0057] In one embodiment, remote unit 105 may include computing devices such as desktop computers, laptop computers, personal digital assistants (“PDAs”), tablet computers, smartphones, smart TVs (e.g., internet-connected TVs), smart appliances (e.g., internet-connected appliances), set-top boxes, game consoles, security systems (including security cameras), in-vehicle computers, network devices (e.g., routers, switches, modems), etc. In some embodiments, remote unit 105 includes wearable devices such as smartwatches, fitness bands, optical head-mounted displays, etc. Furthermore, remote unit 105 may be referred to as UE, subscriber unit, mobile device, mobile station, user, terminal, mobile terminal, fixed terminal, subscriber station, user terminal, wireless transmit / receive unit (“WTRU”), device, or other terms used in the art. In various embodiments, remote unit 105 includes a subscriber identity and / or identification module (“SIM”) and a mobile device (“ME”) that provides mobile terminal functions (e.g., radio transmission, conversion, voice encoding and decoding, error detection and correction, signaling to the SIM, and access). In some embodiments, the remote unit 105 may include a terminal device (“TE”) and / or be embedded in an electrical appliance or device (e.g., a computing device as described above).

[0058] Remote unit 105 can communicate directly with one or more base station units 121 in RAN 120 via uplink (“UL”) and downlink (“DL”) communication signals. Additionally, UL and DL communication signals can be carried on wireless communication link 123. Here, RAN 120 is an intermediate network providing remote unit 105 with access to the mobile core network 140.

[0059] In some embodiments, remote unit 105 communicates with application server 151 via a network connection to mobile core network 140. For example, application 107 in remote unit 105 (e.g., a web browser, media client, telephone, and / or Voice over Internet Protocol (“VoIP”) application) can trigger remote unit 105 to establish a Protocol Data Unit (“PDU”) session (or other data connection) with mobile core network 140 via RAN 120. Mobile core network 140 then uses the PDU session to relay services between remote unit 105 and application server 151 in packet data network 150. The PDU session represents a logical connection between remote unit 105 and user plane function (“UPF”) 141.

[0060] To establish a PDU session (or PDN connection), remote unit 105 must register with mobile core network 140 (also referred to as "attached to mobile core network" in the context of fourth-generation ("4G") systems). Note that remote unit 105 may establish one or more PDU sessions (or other data connections) with mobile core network 140. Therefore, remote unit 105 may have at least one PDU session for communicating with packet data network 150. Remote unit 105 may establish additional PDU sessions for communicating with other data networks and / or other communication peers.

[0061] In the context of a 5G system (“5GS”), the term “PDU session” refers to a data connection that provides end-to-end (“E2E”) user plane (“UP”) connectivity between remote unit 105 and a specific data network (“DN”) via UPF 141. A PDU session supports one or more Quality of Service (“QoS”) streams. In some embodiments, a one-to-one mapping may exist between QoS streams and QoS profiles, such that all packets belonging to a particular QoS stream have the same 5G QoS identifier (“5QI”).

[0062] In the context of 4G / LTE systems such as Evolved Packet System (“EPS”), a Packet Data Network (“PDN”) connection (also known as an EPS session) provides end-to-end (E2E) connectivity between the remote unit and the PDN. The PDN connectivity process establishes an EPS bearer, i.e., a tunnel between the remote unit 105 and the packet gateway (“PGW”, not shown) in the mobile core network 140. In some embodiments, a one-to-one mapping exists between the EPS bearer and the QoS profile, such that all packets belonging to a particular EPS bearer have the same QoS class identifier (“QCI”).

[0063] Base station unit 121 may be distributed across a geographical area. In some embodiments, base station unit 121 may also be referred to as an access terminal, access point, base station, base station, node B (“NB”), evolved Node B (abbreviated as eNodeB or “eNB”, also known as Evolved Universal Terrestrial Radio Access Network (“E-UTRAN”) node B), 5G / NR node B (“gNB”), home node B, relay node, RAN node, or any other term used in the art. Base station unit 121 is typically part of a RAN such as RAN 120, which may include one or more controllers communicatively coupled to one or more corresponding base station units 121. These and other elements of the radio access network are not shown, but are generally well known to those skilled in the art. Base station unit 121 is connected to mobile core network 140 via RAN 120.

[0064] Base station unit 121 can serve multiple remote units 105 within its service area, such as a cell or cell sector, via wireless communication link 123. Base station unit 121 can communicate directly with one or more remote units 105 via communication signals. Typically, base station unit 121 transmits DL communication signals to serve remote units 105 in the time, frequency, and / or spatial domains. Furthermore, DL communication signals can be carried on wireless communication link 123. Wireless communication link 123 can be any suitable carrier in licensed or unlicensed radio spectrum. Wireless communication link 123 facilitates communication between one or more remote units 105 and / or one or more base station units 121. Note that during NR operation (referred to as "NR-U") on unlicensed spectrum, base station unit 121 and remote units 105 communicate via unlicensed (i.e., shared) radio spectrum.

[0065] In one embodiment, the mobile core network 140 is a 5GC or Evolved Packet Core (“EPC”), which may be coupled to a packet data network 150, such as the Internet and private data networks, as well as other data networks. The remote unit 105 may have a subscription or other account with respect to the mobile core network 140. In various embodiments, each mobile core network 140 belongs to a single mobile network operator (“MNO”). This disclosure is not intended to limit implementation to any particular wireless communication system architecture or protocol.

[0066] Mobile core network 140 includes several network functions (“NFs”). As depicted, mobile core network 140 includes at least one UPF 141. Mobile core network 140 also includes multiple control plane (“CP”) functions, including but not limited to Access and Mobility Management Functions (“AMF”) 143, Session Management Functions (“SMF”) 145, Policy Control Functions (“PCF”) 147, Unified Data Management Functions (“UDM”), and User Data Repository (“UDR”) serving RAN 120. Figure 1 The document describes a specific number and type of network functions, but those skilled in the art will recognize that any number and type of network functions may be included in the mobile core network 140.

[0067] In the 5G architecture, (multiple) UPF 141s are responsible for packet routing and forwarding, packet inspection, QoS processing, and external PDU sessions for interconnecting the data network (DN). AMF 143 is responsible for NAS signaling termination, NAS encryption and integrity protection, registration management, connection management, mobility management, access authentication and authorization, and security context management. SMF 145 is responsible for UPF 141 session management (i.e., session establishment, modification, and release), remote unit (i.e., UE) IP address allocation and management, DL data notification, and service orientation configuration for appropriate service routing.

[0068] PCF 147 is responsible for a unified policy framework, providing policy rules for CP functions and accessing subscription information for policy decisions in the UDR. UDM is responsible for generating authentication and key protocol (“AKA”) credentials, user identification processing, access authorization, and subscription management. The UDR is a repository of subscriber information and can be used to serve multiple network functions. For example, the UDR can store subscription data, policy-related data, subscriber-related data that can be exposed to third-party applications, and so on. In some embodiments, the UDM and UDR are co-located and depicted as a combined entity “UDM / UDR” 149.

[0069] In various embodiments, the mobile core network 140 may also include a network repository function (“NRF”) (which provides network function (NF) service registration and discovery, enabling NFs to identify appropriate services among themselves and communicate with each other via an application programming interface (“API”), a network exposure function (“NEF”) (which is responsible for enabling customers and network partners to easily access network data and resources), an authentication server function (“AUSF”), or other NFs defined for the 5GC. When present, the AUSF can be used as an authentication server and / or authentication proxy, thereby allowing AMF 143 to authenticate remote unit 105. In some embodiments, the mobile core network 140 may include an authentication, authorization, and accounting (“AAA”) server.

[0070] In various embodiments, the mobile core network 140 supports different types of mobile data connections and different types of network slices, wherein each mobile data connection utilizes a specific network slice. Here, a "network slice" refers to a portion of the mobile core network 140 optimized for a specific service type or communication service. For example, one or more network slices may be optimized for enhanced mobile broadband ("eMBB") service. As another example, one or more network slices may be optimized for ultra-reliable low-latency communication ("URLLC") service. In other examples, network slices may be optimized for machine-type communication ("MTC") service, massive MTC ("mMTC") service, and Internet of Things ("IoT") service. In still other examples, network slices may be deployed for specific application services, vertical services, specific use cases, etc.

[0071] Network slice instances can be identified by individual network slice selection aid information (“S-NSSAI”), while the set of network slices authorized for use by remote unit 105 is identified by network slice selection aid information (“NSSAI”). Here, “NSSAI” refers to a vector value including one or more S-NSSAI values. In some embodiments, various network slices may include separate instances of network functions, such as SMF 145 and UPF 141. In some embodiments, different network slices may share some common network functions, such as AMF 143. For illustration purposes, Figure 1 Different network slices are not shown, but their support is assumed.

[0072] Although Figure 1 The components of the 5G RAN and 5G core network are described, but the described embodiments for relay announcements for sidelink operations are applicable to other types of communication networks and RATs, including IEEE 802.11 variants, Global System for Mobile Communications (“GSM”, i.e., 2G digital cellular networks), General Packet Radio Service (“GPRS”), General Mobile Telecommunications System (“UMTS”), LTE variants, CDMA 2000, Bluetooth, ZigBee, Sigfox, and others.

[0073] Furthermore, in the LTE variant of the mobile core network 140 where EPC is used, the described network functions can be replaced with appropriate EPC entities, such as the Mobility Management Entity (“MME”), Serving Gateway (“SGW”), PGW, Home Subscriber Server (“HSS”), etc. For example, AMF 143 can be mapped to the MME, SMF 145 can be mapped to the control plane portion of the PGW and / or the MME, UPF 141 can be mapped to the SGW and the user plane portion of the PGW, UDM / UDR 149 can be mapped to the HSS, etc.

[0074] In the following description, the term "RAN node" is used for base station, but it can be replaced by any other radio access node, such as gNB, ng-eNB, eNB, base station ("BS"), access point ("AP"), etc. Furthermore, the operation is primarily described in the context of 5G NR. However, the solutions / methods described below are equally applicable to other mobile communication systems that use relay announcements for sidelink operations.

[0075] In various embodiments, remote units 105 can communicate directly with each other using SL communication link 115 (e.g., device-to-device communication). Here, SL transmissions can occur on SL resources. Remote unit 105 implements an SL HARQ process for at least some data transmitted via SL communication signal 115, as discussed in more detail below.

[0076] In various embodiments, the transmitting remote unit 105 (i.e., the source UE) may not be within the range of direct transmission to the receiving remote unit 105 (i.e., the destination UE). In such embodiments, the transmitting remote unit 105 may use one or more relay units 109 to reach the receiving remote unit. The relay unit 109 may be an embodiment of the remote unit 105, i.e., a UE configured to relay transmissions via the SL communication link 115. The relay units(s) 109 may relay both data packets and HARQ feedback, as discussed in more detail below.

[0077] In NR V2X communication version 16, SL HARQ feedback is used for multicast and unicast communications to improve spectral efficiency. When SL HARQ feedback is enabled for unicast, in non-block group (“CBG”) operation, if the corresponding TB is successfully decoded, the receiver UE (“Rx UE”, i.e., receive remote unit 105) generates a HARQ-ACK. If the corresponding TB is not successfully decoded after decoding the associated PSCCH for the Rx UE, the Rx UE generates a HARQ-NACK.

[0078] Regarding the selection of relay unit 109, remote unit 105 can receive relay announcement 117 from relay unit 109. Many attributes can be announced by relay unit 109, which assists remote unit 105 in deciding whether a given relay unit 109 should be selected.

[0079] The criteria described herein are used by remote unit 105 to determine whether a given relay should be selected. The criteria described herein are used by remote unit 105 to determine when to begin relaying data to another remote unit 105 via relay unit 109. The criteria described herein are used by remote unit 105 to determine when to stop relaying data via the selected relay unit 109.

[0080] Figure 2A This is a block diagram illustrating one embodiment of a relay arrangement 200 for transmitting a TB via unicast transmission according to a simple transmission scenario referred to as "Scenario 1" (e.g., unicast on a sidelink interface). Arrangement 200 involves a Tx-remote-UE (i.e., UE1) 201, which enables some application data to be transmitted via an SL-relay-UE (i.e., UE2) 203 to another remote UE (shown as Rx-remote-UE (i.e., UE3) 205). At different points in time, UE3 205 can transmit data to UE1 201 via UE2 203, and in this scenario, UE3 205 will act as the transmitter UE. Figure 2A The terms and roles shown are relative to a specific data group (i.e., TB).

[0081] like Figure 2A As shown, UE1 201 transmits a TB to UE2 203 via interface 1. UE2 203 then transmits the TB to UE3 205 via a second side link interface (described as "interface-2"). Here, interface-2 can be unicast ("UC") or multicast ("GC"), as indicated by UE1 201 to UE2 203. Alternatively, interface-2 can be broadcast ("BC"), as indicated by UE1 201 to UE2 203. Figure 2A Only one UE3 205 is shown in the image, but it represents one of multiple receivers used in GC or BC scenarios.

[0082] Figure 2A An example of a relay according to the first solution is shown. In some cases, more than one SL relay UE may be available, such as a first SL relay UE, a second SL relay UE, etc. Therefore, "UE2" is a generalized representation of any one or both of these. For multicast and broadcast communications, Rx-Remote-UE (UE3) 205 is a representation of all Rx-Remote-UEs. Note that in another embodiment, Rx-Remote-UE 205 may act as a relay for... Figure 2A The SL relay UE of another destination UE (i.e., UE4) not shown in the diagram.

[0083] In other embodiments, SL-relay-UE 203 represents multiple relay UEs operating in parallel, wherein Tx-remote-UE (i.e., UE1) 201 can transmit TB to multiple SL relay UEs on interface-1 using multicast or multiple unicast links. Alternatively, Tx-remote-UE (i.e., UE1) 201 can transmit TB to multiple SL relay UEs on interface-1 using broadcast.

[0084] Typically, the RAN node sets some criteria, and a candidate relay UE checks whether it meets these criteria; if it does, it can declare itself a relay UE. For a remote UE, there may be more than one visible relay. As used herein, visibility refers to the measured quality of (or less than one) reference signals of the relay UE at the remote UE (i.e., Reference Signal Received Power (“RSRP”) and / or Reference Signal Received Quality (“RSRQ”)) exceeding a certain threshold. The relevant question is how the remote UE will select a particular relay, i.e., based on which criterion besides the radio threshold?

[0085] Figure 2B A PC5 protocol stack 250 according to an embodiment of this disclosure is depicted. Although Figure 2B TX-Remote-UE 201, SL-Relay-UE 203, and RX-Remote-UE 205 are shown, but these are representations of a group of UEs communicating via PC5 peering, and other embodiments may involve different UEs. As depicted, the PC5 protocol stack includes a physical (“PHY”) layer 755 for the control plane and a media access control (“MAC”) sublayer 760, a radio link control (“RLC”) sublayer 765, a packet data convergence protocol (“PDCP”) sublayer 770, and radio resource control (“RRC”) and service data adaptation protocol (“SDAP”) layers (described as a combined element “RRC / SDAP” 775).

[0086] The AS protocol stack for the control plane in the PC5 interface consists of at least RRC, PDCP, RLC, and MAC sublayers, as well as the physical layer. The AS protocol stack for the user plane in the PC5 interface consists of at least SDAP, PDCP, RLC, and MAC sublayers, as well as the physical layer. L2 is divided into SDAP, PDCP, RLC, and MAC sublayers. L3 includes the RRC sublayer and NAS layer for the control plane, and includes, for example, the IP layer for the user plane. L1 and L2 are referred to as "lower layers," while L3 and above (e.g., transport layer, V2X layer, application layer) are referred to as "higher layers" or "upper layers."

[0087] In some embodiments, SL-Relay-UE 203 acts as an L3 relay (also known as an IP relay). Here, communication between Tx-Remote-UE 201 (i.e., the source UE) and Rx-Remote-UE 205 (i.e., the target UE) via the L3 relay passes through two combined PC5 links: a first PC5 link (corresponding to interface-1) between Tx-Remote-UE 201 and SL-Relay-UE 203, and a second PC5 link (corresponding to interface-2) between SL-Remote-UE 203 and Rx-Remote-UE 205. In such an embodiment, the protocol stack of SL-Remote-UE 203 may include SDAP, RRC, PDCP, RLC, MAC, and PHY layers, which interact with the corresponding layers at Tx-Remote-UE 201 via interface-1 and also interact with the corresponding layers at Rx-Remote-UE 205 via interface-2.

[0088] In some embodiments, SL-Relay-UE 203 acts as an L2 relay. In some embodiments, SL-Relay-UE 203, acting as an L2 relay, performs relay functions below PDCP layer 770, such that SL-Relay-UE 203 does not perform PDCP, RRC, and SDAP functions for SL communication. In such embodiments, the protocol stack of SL-Relay-UE 203 may include RLC layer 765, MAC layer 760, and PHY layer 755 entities, which interact with the corresponding layers at Tx-Remote-UE 201 via interface-1 and with the corresponding layers at Rx-Remote-UE 205 via interface-2. However, for PDCP layer 770, RRC, and SDAP layer 775, the link endpoint is between Tx-Remote-UE 201 and Rx-Remote-UE 205.

[0089] In some embodiments, SL-Relay-UE 203 acts as an L1 relay (also known as an amplification and forwarding relay) with HARQ functionality. In some embodiments, the protocol stack of SL-Relay-UE 203 may have a PHY layer 755 (i.e., MAC layer 760) and a HARQ entity, which interacts with the corresponding layer at Tx-Remote-UE 201 via interface-1 and with the corresponding layer at Rx-Remote-UE 205 via interface-2. However, for the remaining layers, the link endpoint is between Tx-Remote-UE 201 and Rx-Remote-UE 205.

[0090] Note that the above relay description is exemplary, and the SL-Relay-UE 203 is not limited to the above relay implementation. Therefore, according to the following solution, the SL-Relay-UE 203 can implement a different protocol stack and / or link endpoint than those described above.

[0091] Figure 3 This is a block diagram illustrating one embodiment of a relay advertisement process 300 according to an embodiment of the present disclosure. Process 300 involves a remote UE (here, Tx-remote-UE 201) and a relay UE (here, SL-relay-UE 203). As shown, SL-relay-UE 203 sends a relay advertisement 305 (containing attributes) to Tx-remote-UE 201.

[0092] Here are some examples of attributes that can be advertised by relays:

[0093] A) Group Membership: The relay UE (i.e., SL-Relay-UE 203) and the remote UE (i.e., Tx-Remote-UE 201) are members of at least one public group, meaning they are members of some public L2 group destination ID. The relay advertises all its L2 group destination IDs;

[0094] B) The relay UE (i.e., SL-relay-UE 203) announces that it supports all broadcast types for relay purposes;

[0095] C) The relay UE (i.e., SL-relay-UE 203) announces one or both of HARQ feedback support and blind retransmission support;

[0096] D) The relay UE (i.e., SL-relay-UE 203) announces its location availability (whether the relay knows its location);

[0097] E) The relay UE (i.e., SL-relay-UE 203) announces its minimum communication range (“MCR”) support capability, i.e., whether it supports finding and monitoring feedback within the MCR and retransmitting data to the receiver remote UE (i.e., Rx-remote-UE 205);

[0098] F) PQI: Due to the involvement of relays, latency will inevitably increase; therefore, not all PQIs can be served by any relay. Furthermore, capabilities at the physical layer, FR2, etc., may vary depending on the relay. Therefore, a relay UE can broadcast the PQIs or PQI ranges it supports for that relay. This can be implemented in several ways, including a bitmap where each bit of the bitmap corresponds to a specific PQI or a specified range of PQIs.

[0099] G) Cell-Id (used for N relays), i.e., the ECGI of the serving cell of the relay. Remote UEs can select their own serving cell or a relay UE in a specific cell; and

[0100] H) Service Type (PS, V2X, Commercial): As an example, a Public Safety (“PS”) Remote UE can select only a PS Relay UE.

[0101] According to an embodiment of the first solution, the remote UE (i.e., Tx-remote-UE 201) will select (i.e., select and / or reselect) one or more relay UEs that are interested in advertising attributes.

[0102] Return to Figure 3 The Tx-Remote-UE 201 additionally determines whether certain other criteria are met (see box 310). Other criteria that may be announced by the relay UE (i.e., SL-Relay-UE 203) include, but are not limited to:

[0103] A) Radio criteria (e.g., the measured RSRP of (multiple) reference signals (such as demodulation reference signal (“DMRS”), channel state information reference signal (“CSI-RS”), or probe reference signal (“SRS”)) of SL-relay-UE 203 with or without filtering is higher than a (pre-)configured threshold);

[0104] B) CSI reports can play a role in relay (re)selection of L3 filter value feedback; for greater reliability, using CSI reports will result in the selection of relay UEs with better radio / higher available bandwidth (“BW”);

[0105] C) Reselection of Interface-2 (e.g., as shown in Figure 2) for Quality Driven Interface-1; and

[0106] D) Geographical distance between SL-relay-UE 203 and Tx-remote-UE 201 when radio guidelines are met: Some Tx-remote-UE 201 may prefer a more distant relay, with the expectation that such a relay is close to one or more Rx-remote-UE 205.

[0107] Return to Figure 3 When selecting a relay UE (i.e., SL-relay-UE 203), Tx-remote-UE 201 sends a connection request message 315 to SL-relay-UE 203. If accepted, SL-relay-UE 203 responds by sending a connection confirmation message 320 to Tx-remote-UE 201.

[0108] According to an embodiment of the second solution, several triggering points are disclosed regarding when the remote UE1 (i.e., Tx-remote-UE 201) begins searching for the relay UE (i.e., SL-relay-UE 203) using the following triggers:

[0109] For UC (unicast) transmissions from Tx Remote-UE 201 to Rx Remote-UE 205, Tx Remote-UE 201 can use one or more of the following triggers:

[0110] Trigger A) after 'n1' unsuccessful attempts to directly reach the UC destination (i.e., UE3). Here, "unsuccessful attempts" implies that in any of the 'n1' attempts made for Tx-Remote-UE 201, Tx-Remote-UE 201 failed to receive any response / transmission / HARQ feedback from Rx-Remote-UE (UE3) 205. "Direct" means without using any relay or intermediate devices. The transmission can be physical signals or higher-layer data such as MAC or RRC signaling or application data.

[0111] Trigger B) When the UC destination (i.e., UE3) is reachable but the link conditions are unsatisfactory, for example,

[0112] HARQ operation points are above a threshold (e.g., always requiring 2 or more retransmissions within a certain period of time).

[0113] Radio conditions (i.e., the difference between the measured RSRP and / or RSRQ of the (multiple) reference signals of Rx-remote-UE 205 and the threshold).

[0114] Radio link failure (“RLF”) has been triggered or is about to be triggered, i.e., radio link monitoring has indicated one or more asynchronous indications to the upper layer, or Tx-Remote-UE 201 has received a certain number of HARQ failures (DTX or NACK).

[0115] Channel State Information (“CSI”) reports indicate the minimum schedulable bandwidth (BW).

[0116] For direct GC (multicast) transmissions from Tx-Remote-UE 201 to Rx-Remote-UE 205 (and other receiver UEs), Tx-Remote-UE 201 can use one or more of the following triggers:

[0117] Trigger A) When the 'n2'th acknowledgment for SL HARQ feedback option 2 is lost (not received at Tx-Remote-UE 201).

[0118] Triggered by B) when “n3” NACKs are received for SL HARQ feedback option 2.

[0119] Trigger C) When the sum of the received NACK and lost feedback (DTX from the receiver UE) for SL HARQ feedback option 2 exceeds “n4”.

[0120] Triggered D) When using SL HARQ feedback option 1, NACK is received "n5" times.

[0121] Trigger E) When Tx-Remote-UE 201 cannot access its location.

[0122] For GC or BC (multicast or broadcast) transmissions from Tx-Remote-UE 201 to Rx-Remote-UE 205 (and other receiver UEs), Tx-Remote-UE 201 can use one or more of the following triggers:

[0123] Trigger A) Battery issues at Tx-Remote-UE 201: For example, the VRU device (pedestrian) may want to reduce its power consumption; or, when the remaining battery in the UE / device is below a certain percentage threshold (such as 15% remaining battery).

[0124] Trigger B) is a resource problem at Tx-Remote-UE 201, such as channel congestion / high CBR, and / or Tx-Remote-UE 201 is outside coverage, making Mode 1 (i.e., network scheduling operation mode) impossible. In these cases, it is more efficient to successfully transmit TB only to a relay UE in favorable radio conditions (i.e., SL-Relay-UE 203).

[0125] Triggered C) When another UC / GC already has a relay available / selected.

[0126] The aforementioned counters n1, n2, n3, etc., can be used for the same or different / subsequent TB transmissions; consecutively or otherwise; and whether there are time limits. Thresholds and counters (such as n1, n2, n3) are (pre-)configured or specified. For multicast, the total member UE information and MCR are signaled from Tx-Remote-UE 201 to SL-Relay-UE 203.

[0127] According to an embodiment of the third solution, for UC / GC / BC, Tx-Remote-UE 201 can begin using the relay UE (i.e., SL-Relay-UE 203) whenever the previously described trigger is met or when a relay reselection occurs. At that point in time, some TBs may have been successfully transmitted and / or certain TBs may still be in transmission.

[0128] In this scenario, Tx-Remote-UE 201 can first complete the transmission of a TB already in transit (successfully or unsuccessfully), or in another implementation, it can immediately abandon the transmission of a TB already in transit. In one implementation of this embodiment, the "next" TB that has not yet been attempted to be transmitted is the first TB transmitted via SL-Relay-UE 203. In another implementation, the last TB that Tx-Remote-UE 201 failed to transmit is the first TB transmitted via SL-Relay-UE 203.

[0129] According to an embodiment of the fourth solution, Tx-Remote-UE 201 determines when the relay UE can be decommissioned (i.e., SL-Relay-UE 203). This can be done when one or more of the following conditions are met:

[0130] A) When no more relays are available to relay to Rx-Remote-UE 205. This may occur when the connection to SL-Relay-UE 203 is weak, or has been lost as in RLF (e.g., due to relative mobility), and no other relay is selected toward Rx-Remote-UE 205 based on the previously described properties and other / radio conditions.

[0131] B) When Rx-Remote UE 205 arrives directly from Tx-Remote UE 201. For this purpose, Tx-Remote UE 201 may need to periodically send transmissions directly to Rx-Remote UE 205 and check if Rx-Remote UE 205 is able to receive them and respond (using HARQ feedback). After this successful operation a certain number of times, Tx-Remote UE 201 can assume that it can directly reach Rx-Remote UE 205, and therefore it can discontinue using SL relay UE 203 towards Rx-Remote UE 205.

[0132] C) When the radio quality (e.g., the measured RSRP of (multiple) reference signals of the SL-relay-UE 203 transmitted by one and measured by another) is higher than a (pre-)configured threshold.

[0133] D) The upper layer terminates the PC5 RRC connection and / or PC5-S link between Tx-Remote-UE 201 and Rx-Remote-UE 205.

[0134] E) There is no longer any data available for Rx-Remote-UE 205.

[0135] Figure 4 A protocol stack 400 according to an embodiment of this disclosure is depicted. Although Figure 4The diagram illustrates a remote unit 105 (i.e., a UE, such as SL-Relay-UE (UE2) 203), a RAN node 415 (i.e., an embodiment of basic unit 121), and a 4G core (“5GC”) 420 (i.e., an embodiment of mobile core network 140), but these are representative of a group of UEs interacting with RAN nodes and NFs (e.g., AMFs) in the core network. As shown, the protocol stack 400 includes a user plane protocol stack 405 and a control plane protocol stack 410. The user plane protocol stack 405 includes physical (“PH”) protocols. The control plane protocol stack 410 also includes a physical layer 415, a MAC sublayer 420, an RLC sublayer 425, a packet data convergence protocol (PDCP) sublayer 430, and a service data adaptation protocol (SDAP) layer 435.

[0136] The AS protocol stack for the control plane protocol stack 410 consists of at least RRC, PDCP, RLC, and MAC sublayers, as well as a physical layer. The AS protocol stack for the user plane protocol stack 405 consists of at least SDAP, PDCP, RLC, and MAC sublayers, as well as a physical layer. Layer 2 (“L2”) is divided into SDAP, PDCP, RLC, and MAC sublayers. Layer 3 (“L3”) includes the RRC sublayer 440 and NAS layer 445 for the control plane, and includes, for example, the Internet Protocol (“IP”) layer or PDU layer (not shown) for the user plane. L1 and L2 are referred to as “lower layers”, such as the Physical Uplink Control Channel (“PUCCH”) and / or the Physical Uplink Shared Channel (“PUSCH”) or MAC control element (“CE”), while L3 and above (e.g., transport layer, application layer) are referred to as “higher layers” or “upper layers”, such as RRC.

[0137] Physical layer 415 provides a transport channel to MAC sublayer 420. MAC sublayer 420 provides a logical channel to RLC sublayer 425. RLC sublayer 425 provides an RLC channel to PDCP sublayer 430. PDCP sublayer 430 provides radio bearers to SDAP sublayer 435 and / or RRC layer 440. SDAP sublayer 435 provides QoS flows to mobile core network 140 (e.g., 4GC). RRC layer 440 provides the addition, modification, and release of carrier aggregation and / or dual connectivity. RRC layer 440 also manages the establishment, configuration, maintenance, and release of signaling radio bearers (“SRBs”) and data radio bearers (“DRBs”). In some embodiments, the RRC entity is used to detect and recover from radio link failures.

[0138] Multiple SL relay UEs communicating with the network can implement the PC5 protocol stack 250 on the SL interface (e.g., interface-1) and the NR protocol stack 400 on the Uu interface (e.g., interface-2).

[0139] Figure 5 User equipment device 500, which can be used for relay notification for sidelink operation according to embodiments of the present disclosure, is depicted. In various embodiments, user equipment device 500 is used to implement one or more of the solutions described above. User equipment device 500 may be an embodiment of the remote unit 105, Tx-remote-UE 201, SL-relay-UE 203, and / or Rx-remote-UE 205 described above. Furthermore, user equipment device 500 may include processor 505, memory 510, input device 515, output device 520, and transceiver 525.

[0140] In some embodiments, input device 515 and output device 520 are combined into a single device, such as a touchscreen. In some embodiments, user equipment device 500 may not include any input device 515 and / or output device 520. In various embodiments, user equipment device 500 may include one or more of the following: processor 505, memory 510, and transceiver 525, and may not include input device 515 and / or output device 520.

[0141] As depicted, transceiver 525 includes at least one transmitter 530 and at least one receiver 535. In some embodiments, transceiver 525 communicates with one or more cells (or radio coverage areas) supported by one or more base station units 121. In various embodiments, transceiver 525 may operate on unlicensed spectrum. Furthermore, transceiver 525 may include multiple UE panels supporting one or more beams. Additionally, transceiver 525 may support at least one network interface 540 and / or application interface 545. The application interface(s) 545 may support one or more APIs. The network interface(s) 540 may support 3GPP reference points such as Uu, N1, PC5, etc. Other network interfaces 540 may be supported, as will be understood by those skilled in the art.

[0142] In one embodiment, processor 505 may include any known controller capable of executing computer-readable instructions and / or performing logical operations. For example, processor 505 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, processor 505 executes instructions stored in memory 510 to perform the methods and routines described herein. Processor 505 is communicatively coupled to memory 510, input device 515, output device 520, and transceiver 525.

[0143] In various embodiments, processor 505 controls user equipment device 500 to implement the UE behavior described above. In some embodiments, processor 505 may include an application processor (also referred to as a "main processor") that manages application domain and operating system ("OS") functions and a baseband processor (also referred to as a "baseband radio processor") that manages radio functions.

[0144] In various embodiments, the user equipment apparatus 500 operates as a Tx remote UE. In such an embodiment, transceiver 525 may receive a relay advertisement from an SL relay UE that supports sidelink operation, wherein the relay advertisement contains at least one relay attribute. Processor 505 uses the at least one relay attribute to determine the relay required via the SL relay UE. Transceiver 525 sends a relay connection request to the SL relay UE and receives a relay connection confirmation from the SL relay UE. Through transceiver 525, processor 505 performs sidelink communication with the Rx remote UE via the SL relay UE.

[0145] In some embodiments, at least one relay attribute includes one or more of the following: HARQ feedback support, support for blind retransmission, supported PC5 QoS identifier (“PQI”), supported playback type, supported service type, distance-based sidelink HARQ feedback communication, minimum communication range (“MCR”) support capability, location availability, and cell identifier of the serving cell.

[0146] In some embodiments, the processor 505 further determines the relay required via the SL relay UE based on one or more of the following: the radio conditions of the interface between the device and the SL relay UE, the radio conditions between the SL relay UE and the Rx remote UE, and the geographical distance between the device 500 and the SL relay UE.

[0147] In some embodiments, the processor 505 searches for candidate SL relay UEs in response to detecting a trigger condition. In such embodiments, the trigger condition may be one or more of the following: a predetermined number of unsuccessful attempts to communicate directly with the Rx remote UE have been made; the condition of the direct link to the Rx remote UE has been determined to be unsatisfactory; and / or the location of the device cannot be accessed, or a predetermined battery state has been reached.

[0148] In some embodiments, the processor 505 searches for candidate SL relay UEs during multicast sidelink communication in response to determining that a threshold number of HARQ feedback acknowledgments have not been received, for example, when a threshold number of ACK responses (for HF option 2) are being lost, when a threshold number of NACK responses (for HF option 1 or HF option 2) are received, and / or when the threshold sum of lost ACK and NACK responses (for HF option 2) is reached.

[0149] In some embodiments, processor 505 detects a trigger to search for candidate SL relay UEs while a first transmission to the Rx remote UE is in progress. In such embodiments, processor 505 may terminate the first transmission in response to detecting the trigger. In some embodiments, performing sidelink communication with the Rx remote UE via the SL relay UE includes transmitting the last data packet (e.g., TB) that was not successfully transmitted to the Rx remote UE.

[0150] In some embodiments, the processor 505 transmits directly to the Rx remote UE while performing sidelink communication with the Rx remote UE via the SL relay UE. In such embodiments, the processor 505 may determine to stop performing sidelink communication with the Rx remote UE via the SL relay UE in response to reaching a threshold number of successful attempts to communicate directly with the Rx remote UE.

[0151] In some embodiments, when performing sidelink communication between the SL relay UE and the Rx remote UE, the processor 505 measures the radio quality of the direct link to the Rx remote UE. In such embodiments, the processor 505 may determine to stop performing sidelink communication between the SL relay UE and the Rx remote UE in response to the radio quality of the direct link to the Rx remote UE exceeding a threshold value.

[0152] In various embodiments, the user equipment device 500 operates as an SL relay UE. In such an embodiment, transceiver 525 can transmit a relay advertisement from an SL relay UE that supports sidelink operation and receive a relay connection request from a Tx remote UE, wherein the relay advertisement contains at least one relay attribute and wherein the Tx remote UE uses at least one relay attribute to select the SL relay UE. Via transceiver 525, processor 505 transmits a relay connection acknowledgment to the Tx remote UE and relays sidelink communication between the Tx remote UE and the Rx remote UE.

[0153] In some embodiments, at least one relay attribute includes one or more of the following: HARQ feedback support, support for blind retransmission, supported PQI, supported playback type, and supported service type. In some embodiments, at least one relay attribute includes one or more of the following: support for distance-based sidelink HARQ feedback communication, minimum communication range support capability, location availability, and cell identifier of the serving cell.

[0154] Note that in the above description, Rx remote UE can instead be RAN node or other network entity, whereby SL relay UE uses a side link to communicate with Tx remote UE and relays communication between Tx remote UE and, for example, RAN node.

[0155] In one embodiment, memory 510 is a computer-readable storage medium. In some embodiments, memory 510 includes volatile computer storage media. For example, memory 510 may include RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and / or static RAM (“SRAM”). In some embodiments, memory 510 includes non-volatile computer storage media. For example, memory 510 may include a hard disk drive, flash memory, or any other suitable non-volatile computer storage device. In some embodiments, memory 510 includes both volatile and non-volatile computer storage media.

[0156] In some embodiments, memory 510 stores data related to relay announcements for sidelink operation. For example, memory 510 may store various parameters, panel / beam configurations, resource assignments, policies, etc., as described above. In some embodiments, memory 510 also stores program code and related data, such as operating systems or other controller algorithms operating on device 500.

[0157] In one embodiment, input device 515 may include any known computer input device, including a touch panel, buttons, keyboard, stylus, microphone, etc. In some embodiments, input device 515 may be integrated with output device 520, for example, as a touchscreen or similar touch-sensitive display. In some embodiments, input device 515 includes a touchscreen, allowing text to be entered using a virtual keyboard displayed on the touchscreen and / or by handwriting input on the touchscreen. In some embodiments, input device 515 includes two or more different devices, such as a keyboard and a touch panel.

[0158] In one embodiment, output device 520 is designed to output visual, auditory, and / or tactile signals. In some embodiments, output device 520 includes an electronically controllable display or display device capable of outputting visual data to a user. For example, output device 520 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 devices capable of outputting images, text, etc., to a user. As another non-limiting example, output device 520 may include a wearable display, such as a smartwatch, smart glasses, a head-up display, etc., separate from but communicatively coupled to the rest of user equipment device 500. Furthermore, output device 520 may be a component of a smartphone, personal digital assistant, television, desktop computer, laptop computer, personal computer, vehicle dashboard, etc.

[0159] In some embodiments, output device 520 includes one or more speakers for generating sound. For example, output device 520 may generate an auditory alarm or notification (e.g., a buzzer or ring). In some embodiments, output device 520 includes one or more haptic devices for generating vibration, motion, or other haptic feedback. In some embodiments, all or part of output device 520 may be integrated with input device 515. For example, input device 515 and output device 520 may form a touchscreen or similar touch-sensitive display. In other embodiments, output device 520 may be located near input device 515.

[0160] Transceiver 525 communicates with one or more network functions of a mobile communication network via one or more access networks. Transceiver 525 operates under the control of processor 505 to transmit and receive messages, data, and other signals. For example, processor 505 may selectively activate transceiver 525 (or a portion thereof) at specific times to send and receive messages.

[0161] Transceiver 525 includes at least a transmitter 530 and at least one receiver 535. One or more transmitters 530 can be used to provide UL communication signals to base station unit 121, such as UL transmissions described herein. Similarly, as described herein, one or more receivers 535 can be used to receive DL communication signals from base station unit 121. Although only one transmitter 530 and one receiver 535 are illustrated, user equipment device 500 can have any suitable number of transmitters 530 and receivers 535. Furthermore, the transmitter(s) 530 and receiver(s) 535 can be of any suitable type. In one embodiment, transceiver 525 includes a first transmitter / receiver pair for communicating with a mobile communication network on licensed radio spectrum and a second transmitter / receiver pair for communicating with a mobile communication network on unlicensed radio spectrum.

[0162] In some embodiments, a first transmitter / receiver pair for communicating with a mobile communication network on licensed radio spectrum and a second transmitter / receiver pair for communicating with a mobile communication network on unlicensed radio spectrum may be combined into a single transceiver unit, such as a single chip performing functions for both 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, some transceivers 525, transmitters 530, and receivers 535 may be implemented as physically separate components that access shared hardware and / or software resources, such as, for example, a network interface 540.

[0163] In various embodiments, one or more transmitters 530 and / or one or more receivers 535 may be implemented and / or integrated into a single hardware component, such as a multi-transceiver chip, a system-on-a-chip, an application-specific integrated circuit (“ASIC”), or other types of hardware components. In some embodiments, one or more transmitters 530 and / or one or more receivers 535 may be implemented and / or integrated into a multi-chip module. In some embodiments, other components such as network interface 540 or other hardware components / circuitets may be integrated with any number of transmitters 530 and / or receivers 535 into a single chip. In such embodiments, transmitters 530 and receivers 535 may be logically configured as transceivers 525 using a plurality of common control signals or as modular transmitters 530 and receivers 535 implemented in the same hardware chip or multi-chip module.

[0164] Figure 6A network device 600 for relay announcements for sidelink operations according to embodiments of the present disclosure is depicted. In one embodiment, the network device 600 may be an implementation of a RAN node, such as base station unit 121 or RAN node 210 as described above. Furthermore, the base station network device 600 may include a processor 605, a memory 610, an input device 615, an output device 620, and a transceiver 625.

[0165] In some embodiments, input device 615 and output device 620 are combined into a single device, such as a touchscreen. In some embodiments, network device 600 may not include any input device 615 and / or output device 620. In various embodiments, network device 600 may include one or more of the following: processor 605, memory 610, and transceiver 625, and may not include input device 615 and / or output device 620.

[0166] As depicted, transceiver 625 includes at least one transmitter 630 and at least one receiver 635. Here, transceiver 625 communicates with one or more remote units 105. Additionally, transceiver 625 may support at least one network interface 640 and / or application interface 645. The application interfaces 645 may support one or more APIs. The network interfaces 640 may support 3GPP reference points such as Uu, N1, N2, and N3. Other network interfaces 640 may be supported, as will be understood by those skilled in the art.

[0167] In one embodiment, processor 605 may include any known controller capable of executing computer-readable instructions and / or performing logical operations. For example, processor 605 may be a microcontroller, microprocessor, CPU, GPU, auxiliary processing unit, FPGA, or similar programmable controller. In some embodiments, processor 605 executes instructions stored in memory 610 to perform the methods and routines described herein. Processor 605 is communicatively coupled to memory 610, input device 615, output device 620, and transceiver 625.

[0168] In various embodiments, network device 600 is a RAN node (e.g., gNB) communicating with one or more UEs, as described herein. In such embodiments, processor 605 controls network device 600 to perform the RAN behaviors described above. When operating as a RAN node, processor 605 may include an application processor (also referred to as a "main processor") that manages application domain and operating system ("OS") functions, and a baseband processor (also referred to as a "baseband radio processor") that manages radio functions.

[0169] In various embodiments, processor 605 controls transceiver 625 to communicate with a UE via SL relay UE. In one embodiment, SL relay UE uses a sidelink to communicate with Tx remote UE and relays communication between Tx remote UE and device 600. In another embodiment, SL relay UE uses a sidelink to communicate with Rx remote UE and relays communication between Rx remote UE and device 600.

[0170] In one embodiment, memory 610 is a computer-readable storage medium. In some embodiments, memory 610 includes volatile computer storage media. For example, memory 610 may include RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and / or static RAM (“SRAM”). In some embodiments, memory 610 includes non-volatile computer storage media. For example, memory 610 may include a hard disk drive, flash memory, or any other suitable non-volatile computer storage device. In some embodiments, memory 610 includes both volatile and non-volatile computer storage media.

[0171] In some embodiments, memory 610 stores data related to relay announcements for sidelink operations. For example, memory 610 may store parameters, configurations, resource assignments, policies, etc., as described above. In some embodiments, memory 610 also stores program code and related data, such as an operating system or other controller algorithms operating on device 600.

[0172] In one embodiment, input device 615 may include any known computer input device, including a touch panel, buttons, keyboard, stylus, microphone, etc. In some embodiments, input device 615 may be integrated with output device 620, for example, as a touchscreen or similar touch-sensitive display. In some embodiments, input device 615 includes a touchscreen, allowing text to be entered using a virtual keyboard displayed on the touchscreen and / or by handwriting input on the touchscreen. In some embodiments, input device 615 includes two or more different devices, such as a keyboard and a touch panel.

[0173] In one embodiment, output device 620 is designed to output visual, auditory, and / or tactile signals. In some embodiments, output device 620 includes an electronically controllable display or display device capable of outputting visual data to a user. For example, output device 620 may include, but is not limited to, LCD displays, LED displays, OLED displays, projectors, or similar display devices capable of outputting images, text, etc., to a user. As another non-limiting example, output device 620 may include a wearable display, such as a smartwatch, smart glasses, head-up display, etc., separate from but communicatively coupled to the rest of network device 600. Furthermore, output device 620 may be a component of a smartphone, personal digital assistant, television, desktop computer, laptop computer, personal computer, vehicle dashboard, etc.

[0174] In some embodiments, output device 620 includes one or more speakers for generating sound. For example, output device 620 may generate an auditory alarm or notification (e.g., a buzzer or ring). In some embodiments, output device 620 includes one or more haptic devices for generating vibration, motion, or other haptic feedback. In some embodiments, all or part of output device 620 may be integrated with input device 615. For example, input device 615 and output device 620 may form a touchscreen or similar touch-sensitive display. In other embodiments, output device 620 may be located near input device 615.

[0175] Transceiver 625 includes at least a transmitter 630 and at least one receiver 635. As described herein, one or more transmitters 630 can be used to communicate with a UE. Similarly, as described herein, one or more receivers 635 can be used to communicate with network functions in a PLMN and / or RAN. Although only one transmitter 630 and one receiver 635 are illustrated, network device 600 can have any suitable number of transmitters 630 and receivers 635. Furthermore, the transmitter(s)630 and receiver(s)635 can be of any suitable type.

[0176] Figure 7 One embodiment of a method 700 for relay notification for sidelink operation according to embodiments of the present disclosure is described. In various embodiments, method 700 is performed by a user equipment device in a mobile communication network, such as the remote unit 105, Tx-remote-UE (i.e., UE1) 201, Rx-remote-UE (i.e., UE3) 205, and / or user equipment device 500 described above. In some embodiments, method 700 is performed by a processor, such as a microcontroller, microprocessor, CPU, GPU, auxiliary processing unit, FPGA, etc.

[0177] Method 700 begins and receives a 705 trunk advertisement from an SL trunk UE supporting sidelink operation, wherein the trunk advertisement contains at least one trunk attribute. Method 700 includes using at least one trunk attribute to determine 710 that a trunk connection via the SL trunk UE is required. Method 700 includes sending a 715 trunk connection request to the SL trunk UE and receiving a 720 trunk connection confirmation from the SL trunk UE. Method 700 includes performing 725 sidelink communication with an Rx remote UE via the SL trunk UE. Method 700 ends.

[0178] Figure 8 One embodiment of a method 800 for relay notification for sidelink operation according to embodiments of the present disclosure is described. In various embodiments, method 800 is performed by a sidelink SL relay UE in a mobile communication network, such as the remote unit 105 described above, SL relay UE (i.e., UE2) 203, and / or user equipment device 500. In some embodiments, method 800 is performed by a processor, such as a microcontroller, microprocessor, CPU, GPU, auxiliary processing unit, FPGA, etc.

[0179] Method 800 begins by transmitting a relay advertisement 805 from an SL relay UE supporting sidelink operation, wherein the relay advertisement contains at least one relay attribute. Method 800 includes receiving a relay connection request 810 from a remote transmitter device, wherein the remote transmitter device selects the SL relay UE using at least one relay attribute. Method 800 includes transmitting a relay connection confirmation 815 to the remote transmitter device. Method 800 includes relay 820 for sidelink communication between the remote transmitter device and the remote receiver device. Method 800 ends.

[0180] This document discloses a first apparatus for relay notification for sidelink operation according to embodiments of the present disclosure. The first apparatus may be implemented by a transmitting remote UE device in a mobile communication network, such as the remote unit 105 described above, Tx-remote-UE (i.e., UE1) 201, and / or user equipment device 500. The first apparatus includes a processor and a transceiver that receives a relay notification from a SL relay UE supporting sidelink operation, wherein the relay notification contains at least one relay attribute. The processor uses the at least one relay attribute to determine the relay required via the SL relay UE. The transceiver sends a relay connection request to the SL relay UE and receives a relay connection confirmation from the SL relay UE. Via the transceiver, the processor performs sidelink communication with a remote receiver device via the SL relay UE.

[0181] In some embodiments, at least one relay attribute includes one or more of the following: HARQ feedback support, support for blind retransmission, supported PC5 QoS identifier (“PQI”), supported playback type, supported service type, support for distance-based sidelink HARQ feedback communication, minimum communication range support capability, location availability, and cell identifier of the serving cell.

[0182] In some embodiments, the processor further determines the relay required via the SL relay UE based on one or more of the following: the radio conditions of the interface between the device and the SL relay UE, the radio conditions between the SL relay UE and the remote receiver device, and the geographical distance between the device and the SL relay UE.

[0183] In some embodiments, the processor searches for candidate SL relay UEs in response to detecting a trigger condition. In such embodiments, the trigger condition may be one or more of the following: a predetermined number of unsuccessful attempts to communicate directly with the remote receiver device reach a predetermined number; the condition of the direct link to the remote receiver device is determined to be unsatisfactory; and / or the location of the device cannot be accessed, or a predetermined battery state is reached.

[0184] In some embodiments, the processor searches for candidate SL relay UEs during multicast sidelink communication in response to determining that no threshold number of HARQ feedback acknowledgments have been received, for example, when a threshold number of ACK responses (for HF option 2) are being lost, when a threshold number of NACK responses (for HF option 1 or HF option 2) are received, and / or when the total threshold of lost ACK and NACK responses (for HF option 2) is reached.

[0185] In some embodiments, while a first transmission to a remote receiver device is in progress, the processor detects a trigger for searching candidate SL relay UEs. In such embodiments, the processor may terminate the first transmission in response to detecting the trigger. In some embodiments, performing sidelink communication with the remote receiver device via the SL relay UE includes transmitting the last data packet (e.g., TB) that was not successfully transmitted to the remote receiver device.

[0186] In some embodiments, the processor transmits directly to the remote receiver device while performing sidelink communication between the SL relay UE and the remote receiver device. In such embodiments, the processor may determine to stop performing sidelink communication between the SL relay UE and the remote receiver device in response to reaching a threshold number of successful attempts to communicate directly with the remote receiver device.

[0187] In some embodiments, while performing sidelink communication between the SL relay UE and the remote receiver device, the processor measures the radio quality of the direct link to the remote receiver device. In such embodiments, the processor may determine to stop performing sidelink communication between the SL relay UE and the remote receiver device in response to the radio quality of the direct link to the remote receiver device exceeding a threshold value.

[0188] This document discloses a first method for relay notification for sidelink operation according to embodiments of the present disclosure. The first method can be performed by a transmitting remote UE device in a mobile communication network, such as the remote unit 105 described above, Tx-remote-UE (i.e., UE1) 201, and / or user equipment device 500. The first method includes receiving a relay notification from an SL relay UE supporting sidelink operation, wherein the relay notification includes at least one relay attribute. The first method includes using the at least one relay attribute to determine a relay required via the SL relay UE and sending a relay connection request to the SL relay UE. The first method includes receiving a relay connection confirmation from the SL relay UE and performing sidelink communication with a remote receiver device via the SL relay UE.

[0189] In some embodiments, at least one relay attribute includes one or more of the following: HARQ feedback support, support for blind retransmission, supported PC5 QoS identifier (“PQI”), supported playback type, supported service type, support for distance-based sidelink HARQ feedback communication, minimum communication range support capability, location availability, and cell identifier of the serving cell.

[0190] In some embodiments, the first method includes determining the need for relaying via the SL relay UE based on one or more of the following: radio conditions of the interface between the transmitting remote UE device and the SL relay UE, radio conditions between the SL relay UE and the remote receiving device, and the geographical distance between the transmitting remote UE device and the SL relay UE.

[0191] In some embodiments, the first method includes searching for candidate SL relay UEs in response to detecting a trigger condition. In such embodiments, the trigger condition may be one or more of the following: a predetermined number of unsuccessful attempts to communicate directly with a remote receiver device reach a predetermined number; the condition of the direct link to the remote receiver device is determined to be unsatisfactory; and / or the location of the transmitting remote UE device cannot be accessed, or a predetermined battery state is reached.

[0192] In some embodiments, the first method includes searching for candidate SL relay UEs during multicast sidelink communication in response to determining that no threshold number of HARQ feedback acknowledgments have been received, for example, when a threshold number of ACK responses (for HF option 2) are being lost, when a threshold number of NACK responses (for HF option 1 or HF option 2) are received, and / or when the threshold sum of lost ACK and NACK responses (for HF option 2) is reached.

[0193] In some embodiments, the first method includes detecting a trigger to search for candidate SL relay UEs while a first transmission to a remote receiver device is in progress. In such embodiments, the first method may include terminating the first transmission in response to detecting the trigger. In some embodiments, performing sidelink communication with the remote receiver device via the SL relay UE includes transmitting the last data packet (e.g., TB) that was not successfully transmitted to the remote receiver device.

[0194] In some embodiments, the first method includes sending transmissions directly to the remote receiver device while performing sidelink communication between the SL relay UE and the remote receiver device. In such embodiments, the first method includes determining to stop performing sidelink communication between the SL relay UE and the remote receiver device in response to reaching a threshold number of successful attempts to communicate directly with the remote receiver device.

[0195] In some embodiments, the first method includes measuring the radio quality of the direct link to the remote receiver device while performing sidelink communication between the SL relay UE and the remote receiver device. In such embodiments, the first method includes determining to stop performing sidelink communication between the SL relay UE and the remote receiver device in response to the radio quality of the direct link to the remote receiver device exceeding a threshold value.

[0196] This document discloses a second apparatus for relay notification for sidelink operation according to embodiments of the present disclosure. The second apparatus can be implemented by a sidelink SL relay UE in a mobile communication network, such as the remote unit 105 described above, the SL-relay UE (i.e., UE2) 203, and / or the user equipment apparatus 500. The second apparatus includes a processor and a transceiver that transmits a relay notification from the SL relay UE supporting sidelink operation and receives a relay connection request from a remote transmitter device, wherein the relay notification includes at least one relay attribute and wherein the remote transmitter device uses at least one relay attribute to select the SL relay UE. The transceiver transmits a relay connection acknowledgment to the remote transmitter device, and the processor relays sidelink communication between the remote transmitter device and the remote receiver device.

[0197] In some embodiments, at least one relay attribute includes one or more of the following: HARQ feedback support, support for blind retransmission, supported PQI, supported playback type, and supported service type. In some embodiments, at least one relay attribute includes one or more of the following: support for distance-based sidelink HARQ feedback communication, minimum communication range support capability, location availability, and cell identifier of the serving cell.

[0198] This document discloses a second method for relay notification for sidelink operation according to embodiments of the present disclosure. The second method can be performed by a sidelink SL relay UE in a mobile communication network, such as the remote unit 105 described above, the SL-relay UE (i.e., UE2) 203, and / or the user equipment device 500. The second method includes transmitting a relay notification from the SL relay UE supporting sidelink operation and receiving a relay connection request from a remote transmitter device, wherein the relay notification includes at least one relay attribute, and wherein the remote transmitter device uses at least one relay attribute to select the SL relay UE. The second method includes transmitting a relay connection confirmation to the remote transmitter device and relaying sidelink communication between the remote transmitter device and the remote receiver device.

[0199] In some embodiments, at least one relay attribute includes one or more of the following: HARQ feedback support, support for blind retransmission, supported PQI, supported playback type, and supported service type. In some embodiments, at least one relay attribute includes one or more of the following: support for distance-based sidelink HARQ feedback communication, minimum communication range support capability, location availability, and cell identifier of the serving cell.

[0200] The embodiments may be practiced in other specific forms. The described embodiments are to be considered in all respects as illustrative rather than restrictive. Therefore, the scope of the invention is indicated by the appended claims rather than by the foregoing description. All variations within the equivalent meaning and scope of the claims should be covered within their scope.

Claims

1. A user equipment ("UE") apparatus, comprising: Memory: and A processor, coupled to the memory, is configured to cause the device to: A relay announcement is received from an SL relay UE that supports sidelink operation, wherein the relay announcement contains at least one relay attribute. The at least one relay attribute includes one or more of the following: HARQ feedback support Support for blind retransmission Supported PC5 QoS identifier ("PQI") range, Supported playback types Supported service types Minimum Communication Range ("MCR") support capability Location availability, or combinations thereof; The at least one relay attribute is used to determine the relay that needs to be relayed to the UE via the SL; Send a relay connection request to the SL relay UE; Receive a relay connection confirmation from the SL relay UE; and Perform sidelink communication between the UE and the remote receiver device via the SL relay.

2. The apparatus according to claim 1, wherein, The at least one relay attribute includes one or more of the following: Support for distance-based sidelink HARQ feedback communication Community signage serving the neighborhood, Or a combination thereof.

3. The apparatus according to claim 1, wherein, The processor further determines the relay required via the SL to the UE based on one or more of the following: The radio conditions of the interface between the device and the SL relay UE The radio conditions between the SL relay UE and the remote receiver device The geographical distance between the device and the SL relay UE Or a combination thereof.

4. A method for a user equipment ("UE"), the method comprising: Receive a relay announcement from an SL relay UE that supports sidelink operation, wherein the relay announcement contains at least one relay attribute; The at least one relay attribute is used to determine the relay that needs to be relayed to the UE via the SL. The at least one relay attribute includes one or more of the following: HARQ feedback support Support for blind retransmission Supported PC5 QoS identifier ("PQI") range, Supported playback types Supported service types Minimum Communication Range ("MCR") support capability Location availability, or combinations thereof; Send a relay connection request to the SL relay UE; Receive a relay connection confirmation from the SL relay UE; and Perform sidelink communication between the UE and the remote receiver device via the SL relay.

5. A relay user equipment ("UE") apparatus, the apparatus comprising: Memory: and A processor, coupled to the memory, is configured to cause the device to: Transmit a relay announcement supporting sidelink operation, wherein the relay announcement includes at least one relay attribute for selecting a sidelink relay. The at least one relay attribute includes one or more of the following: HARQ feedback support Support for blind retransmission Supported PC5 QoS identifier ("PQI") range, Supported playback types Supported service types Minimum Communication Range ("MCR") support capability Location availability, or combinations thereof; Receive a relay connection request from a remote transmitter device; Transmitting a relay connection confirmation to the remote transmitter device; and Relay the sidelink communication between the remote transmitter device and the remote receiver device.

6. The apparatus according to claim 5, wherein, The at least one relay attribute includes one or more of the following: Support for distance-based sidelink HARQ feedback communication Community signage serving the neighborhood, Or a combination thereof.

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