WO2025043463A1

WO2025043463A1 - Protocol and architecture for multi-hop ue-to-network relay

Info

Publication number: WO2025043463A1
Application number: PCT/CN2023/115381
Authority: WO
Inventors: Jianhua Liu; Karthika Paladugu; Hong Cheng
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2023-08-29
Filing date: 2023-08-29
Publication date: 2025-03-06
Anticipated expiration: 2026-02-28

Abstract

Certain aspects of the present disclosure provide a method for wireless communications by a remote user equipment (UE), generally including establishing at least a first link with a first relay UE and communicating with a network entity via the first relay UE and at least a second relay UE, wherein the communicating involves exchanging packets with the first relay UE via the first link using a sidelink relay adaptation protocol (SRAP) layer at the remote UE.

Description

PROTOCOL AND ARCHITECTURE FOR MULTI-HOP UE-TO-NETWORK RELAY

BACKGROUND

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for supporting multi-hop relaying between a user equipment (UE) and a network.

Description of Related Art

Wireless communications systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, or other similar types of services. These wireless communications systems may employ multiple-access technologies capable of supporting communications with multiple users by sharing available wireless communications system resources with those users.

Although wireless communications systems have made great technological advancements over many years, challenges still exist. For example, complex and dynamic environments can still attenuate or block signals between wireless transmitters and wireless receivers. Accordingly, there is a continuous desire to improve the technical performance of wireless communications systems, including, for example: improving speed and data carrying capacity of communications, improving efficiency of the use of shared communications mediums, reducing power used by transmitters and receivers while performing communications, improving reliability of wireless communications, avoiding redundant transmissions and/or receptions and related processing, improving the coverage area of wireless communications, increasing the number and types of devices that can access wireless communications systems, increasing the ability for different types of devices to intercommunicate, increasing the number and type of wireless communications mediums available for use, and the like. Consequently, there exists a need for further improvements in wireless communications systems to overcome the aforementioned technical challenges and others.

SUMMARY

One aspect provides a method for wireless communications by a remote user equipment (UE) . The method includes establishing at least a first link with a first relay UE; and communicating with a network entity via the first relay UE and at least a second relay UE, wherein the communicating involves exchanging packets with the first relay UE via the first link using a sidelink relay adaptation protocol (SRAP) layer at the remote UE.

Another aspect provides a method for wireless communications by a first relay user equipment (UE) . The method includes establishing at least a first link with a remote UE; establishing at least a second link with a second relay UE; and relaying packets between the remote UE and the second relay UE using a sidelink relay adaptation protocol (SRAP) layer at the first relay UE.

Another aspect provides a method for wireless communications by a second relay user equipment (UE) . The method includes establishing at least a first link with a network entity; establishing at least a second link with a first relay UE; and relaying packets between the network entity and a remote UE via the second relay UE using a sidelink relay adaptation protocol (SRAP) layer at the second relay UE.

Other aspects provide: an apparatus operable, configured, or otherwise adapted to perform any one or more of the aforementioned methods and/or those described elsewhere herein; a non-transitory, computer-readable media comprising instructions that, when executed by a processor of an apparatus, cause the apparatus to perform the aforementioned methods as well as those described elsewhere herein; a computer program product embodied on a computer-readable storage medium comprising code for performing the aforementioned methods as well as those described elsewhere herein; and/or an apparatus comprising means for performing the aforementioned methods as well as those described elsewhere herein. By way of example, an apparatus may comprise a processing system, a device with a processing system, or processing systems cooperating over one or more networks.

The following description and the appended figures set forth certain features for purposes of illustration.

BRIEF DESCRIPTION OF DRAWINGS

The appended figures depict certain features of the various aspects described herein and are not to be considered limiting of the scope of this disclosure.

FIG. 1 depicts an example wireless communications network.

FIG. 2 depicts an example disaggregated base station architecture.

FIG. 3 depicts aspects of an example base station and an example user equipment.

FIGS. 4A, 4B, 4C, and 4D depict various example aspects of data structures for a wireless communications network.

FIG. 5 depicts an example of relaying between a network and remote UE.

FIGs. 6A and 6B depict example protocol stacks for relaying between a network and remote UE.

FIG. 7 depicts an example control plane protocol stack for relaying between a network and remote UE.

FIG. 8 depicts an example user plane protocol stack for relaying between a network and remote UE.

FIGs. 9A and 9B depict examples of single hop and multi-hop relaying, respectively.

FIGs. 10 and 11 depict example call flow diagrams for multi-hop relaying with independent hop link management, in accordance with aspects of the present disclosure.

FIG. 12 depicts an example call flow diagram for multi-hop relaying with network controlled hop link management, in accordance with aspects of the present disclosure.

FIGs. 13 and 14 depict example call flow diagrams for multi-hop relaying with combined Layer-2 and Layer-3 based relaying, in accordance with aspects of the present disclosure.

FIG. 15 depicts a method for wireless communications.

FIG. 16 depicts a method for wireless communications.

FIG. 17 depicts a method for wireless communications.

FIG. 18 depicts aspects of an example communications device.

DETAILED DESCRIPTION

In certain wireless networks, relaying may be utilized to extend or improve network coverage to certain remote UEs. In such cases, a UE may serve as a relay device. Such a UE (which may be referred to as a relay UE or simply a relay) may relay downlink traffic from the network to remote UE and may relay uplink traffic from the remote UE to the network.

A (cellular) connection between the relay and the network entity, may be called a Uu connection or via a Uu path. A (sidelink) connection between the remote UE and the relay, may be called a PC5 connection or via a PC5 path. The PC5 connection is a device-to-device connection that may take advantage of the comparative proximity between the remote UE and the relay UE (e.g., when the remote UE is closer to the relay UE than to the closest base station) . The relay UE may connect to an infrastructure node (e.g., gNB) via a Uu connection and relay the Uu connection to the remote UE through the PC5 connection.

Current wireless systems that utilize relays for coverage extension may be limited to single-hop relays. In other words, the data path between a remote UE and the network includes only one single-hop relay. In this context, a hop generally refers to a number of entities that a transmission (e.g., a packet) passes through from its source to its destination. Thus, if a data path from a remote UE to the network includes just one relay, that relay is referred to as a single-hop relay.

Certain aspects of the present disclosure provide example architectures and protocols that may help enable and support multi-hop relaying. According to certain aspects, multi-hop relaying is supported using independent hop link management, where an intermediate relay UE is not visible to a network entity (e.g., a gNB) and there is no connection between the intermediate relay UE and the network. According to certain aspects, multi-hop relaying is supported using network controlled hop link management, where relays, including intermediate relay UEs and donor relay UEs are visible to the network entity and there is radio resource control (RRC) connection between the intermediate/donor relay UEs and the network entity. According to certain aspects, multi- hop relaying is supported using combined Layer-2 and Layer-3 based relaying. In such cases, a single-hop Layer-3 based UE to network (U2N) relay may be used between a remote UE and the network, while a multi-hop Layer-2 based UE to UE (U2U) relay may be used between the remote UE and the donor relay UE.

By supporting multi-hop relaying, aspects of the present disclosure may provide for better network coverage of remote UEs and, which may result in more efficient use of network resources and improved user experience.

Introduction to Wireless Communications Networks

The techniques and methods described herein may be used for various wireless communications networks. While aspects may be described herein using terminology commonly associated with 3G, 4G, and/or 5G wireless technologies, aspects of the present disclosure may likewise be applicable to other communications systems and standards not explicitly mentioned herein.

FIG. 1 depicts an example of a wireless communications network 100, in which aspects described herein may be implemented.

Generally, wireless communications network 100 includes various network entities (alternatively, network elements or network nodes) . A network entity is generally a communications device and/or a communications function performed by a communications device (e.g., a user equipment (UE) , a base station (BS) , a component of a BS, a server, etc. ) . For example, various functions of a network as well as various devices associated with and interacting with a network may be considered network entities. Further, wireless communications network 100 includes terrestrial aspects, such as ground-based network entities (e.g., BSs 102) , and non-terrestrial aspects, such as satellite 140 and aircraft 145, which may include network entities on-board (e.g., one or more BSs) capable of communicating with other network elements (e.g., terrestrial BSs) and user equipments.

In the depicted example, wireless communications network 100 includes BSs 102, UEs 104, and one or more core networks, such as an Evolved Packet Core (EPC) 160 and 5G Core (5GC) network 190, which interoperate to provide communications services over various communications links, including wired and wireless links.

FIG. 1 depicts various example UEs 104, which may more generally include: a cellular phone, smart phone, session initiation protocol (SIP) phone, laptop, personal digital assistant (PDA) , satellite radio, global positioning system, multimedia device, video device, digital audio player, camera, game console, tablet, smart device, wearable device, vehicle, electric meter, gas pump, large or small kitchen appliance, healthcare device, implant, sensor/actuator, display, internet of things (IoT) devices, always on (AON) devices, edge processing devices, or other similar devices. UEs 104 may also be referred to more generally as a mobile device, a wireless device, a wireless communications device, a station, a mobile station, a subscriber station, a mobile subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a remote device, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, and others.

BSs 102 wirelessly communicate with (e.g., transmit signals to or receive signals from) UEs 104 via communications links 120. The communications links 120 between BSs 102 and UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a BS 102 and/or downlink (DL) (also referred to as forward link) transmissions from a BS 102 to a UE 104. The communications links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity in various aspects.

BSs 102 may generally include: a NodeB, enhanced NodeB (eNB) , next generation enhanced NodeB (ng-eNB) , next generation NodeB (gNB or gNodeB) , access point, base transceiver station, radio base station, radio transceiver, transceiver function, transmission reception point, and/or others. Each of BSs 102 may provide communications coverage for a respective geographic coverage area 110, which may sometimes be referred to as a cell, and which may overlap in some cases (e.g., small cell 102’ may have a coverage area 110’ that overlaps the coverage area 110 of a macro cell) . A BS may, for example, provide communications coverage for a macro cell (covering relatively large geographic area) , a pico cell (covering relatively smaller geographic area, such as a sports stadium) , a femto cell (relatively smaller geographic area (e.g., a home) ) , and/or other types of cells.

While BSs 102 are depicted in various aspects as unitary communications devices, BSs 102 may be implemented in various configurations. For example, one or more components of a base station may be disaggregated, including a central unit (CU) , one or more distributed units (DUs) , one or more radio units (RUs) , a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC) , or a Non-Real Time (Non-RT) RIC, to name a few examples. In another example, various aspects of a base station may be virtualized. More generally, a base station (e.g., BS 102) may include components that are located at a single physical location or components located at various physical locations. In examples in which a base station includes components that are located at various physical locations, the various components may each perform functions such that, collectively, the various components achieve functionality that is similar to a base station that is located at a single physical location. In some aspects, a base station including components that are located at various physical locations may be referred to as a disaggregated radio access network architecture, such as an Open RAN (O-RAN) or Virtualized RAN (VRAN) architecture. FIG. 2 depicts and describes an example disaggregated base station architecture.

Different BSs 102 within wireless communications network 100 may also be configured to support different radio access technologies, such as 3G, 4G, and/or 5G. For example, BSs 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN) ) may interface with the EPC 160 through first backhaul links 132 (e.g., an S1 interface) . BSs 102 configured for 5G (e.g., 5G NR or Next Generation RAN (NG-RAN) ) may interface with 5GC 190 through second backhaul links 184. BSs 102 may communicate directly or indirectly (e.g., through the EPC 160 or 5GC 190) with each other over third backhaul links 134 (e.g., X2 interface) , which may be wired or wireless.

Wireless communications network 100 may subdivide the electromagnetic spectrum into various classes, bands, channels, or other features. In some aspects, the subdivision is provided based on wavelength and frequency, where frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, or a subband. For example, 3GPP currently defines Frequency Range 1 (FR1) as including 410 MHz –7125 MHz, which is often referred to (interchangeably) as “Sub-6 GHz” . Similarly, 3GPP currently defines Frequency Range 2 (FR2) as including 24,250 MHz –52,600 MHz, which is sometimes referred to (interchangeably) as a “millimeter wave” ( “mmW” or “mmWave” ) . A base station configured to communicate using mmWave/near mmWave radio frequency bands (e.g., a mmWave base station such as BS 180) may utilizebeamforming (e.g., 182) with a UE (e.g., 104) to improve path loss and range.

The communications links 120 between BSs 102 and, for example, UEs 104, may be through one or more carriers, which may have different bandwidths (e.g., 5, 10, 15, 20, 100, 400, and/or other MHz) , and which may be aggregated in various aspects. Carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL) .

Communications using higher frequency bands may have higher path loss and a shorter range compared to lower frequency communications. Accordingly, certain base stations (e.g., 180 in FIG. 1) may utilize beamforming 182 with a UE 104 to improve path loss and range. For example, BS 180 and the UE 104 may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming. In some cases, BS 180 may transmit a beamformed signal to UE 104 in one or more transmit directions 182’ . UE 104 may receive the beamformed signal from the BS 180 in one or more receive directions 182” . UE 104 may also transmit a beamformed signal to the BS 180 in one or more transmit directions 182” . BS 180 may also receive the beamformed signal from UE 104 in one or more receive directions 182’ . BS 180 and UE 104 may then perform beam training to determine the best receive and transmit directions for each of BS 180 and UE 104. Notably, the transmit and receive directions for BS 180 may or may not be the same. Similarly, the transmit and receive directions for UE 104 may or may not be the same.

Wireless communications network 100 further includes a Wi-Fi AP 150 in communication with Wi-Fi stations (STAs) 152 via communications links 154 in, for example, a 2.4 GHz and/or 5 GHz unlicensed frequency spectrum.

Certain UEs 104 may communicate with each other using device-to-device (D2D) communications link 158. D2D communications link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH) , a physical sidelink discovery channel (PSDCH) , a physical sidelink shared channel (PSSCH) , a physical sidelink control channel (PSCCH) , and/or a physical sidelink feedback channel (PSFCH) .

EPC 160 may include various functional components, including: a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and/or a Packet Data Network (PDN) Gateway 172, such as in the depicted example. MME 162 may be in communication with a Home Subscriber Server (HSS) 174. MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, MME 162 provides bearer and connection management.

Generally, user Internet protocol (IP) packets are transferred through Serving Gateway 166, which itself is connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation as well as other functions. PDN Gateway 172 and the BM-SC 170 are connected to IP Services 176, which may include, for example, the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a Packet Switched (PS) streaming service, and/or other IP services.

BM-SC 170 may provide functions for MBMS user service provisioning and delivery. BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN) , and/or may be used to schedule MBMS transmissions. MBMS Gateway 168 may be used to distribute MBMS traffic to the BSs 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and/or may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

5GC 190 may include various functional components, including: an Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. AMF 192 may be in communication with Unified Data Management (UDM) 196.

AMF 192 is a control node that processes signaling between UEs 104 and 5GC 190. AMF 192 provides, for example, quality of service (QoS) flow and session management.

Internet protocol (IP) packets are transferred through UPF 195, which is connected to the IP Services 197, and which provides UE IP address allocation as well as other functions for 5GC 190. IP Services 197 may include, for example, the Internet, an intranet, an IMS, a PS streaming service, and/or other IP services.

In various aspects, a network entity or network node can be implemented as an aggregated base station, as a disaggregated base station, a component of a base station, an integrated access and backhaul (IAB) node, a relay node, a sidelink node, to name a few examples.

FIG. 2 depicts an example disaggregated base station 200 architecture. The disaggregated base station 200 architecture may include one or more central units (CUs) 210 that can communicate directly with a core network 220 via a backhaul link, or indirectly with the core network 220 through one or more disaggregated base station units (such as a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC) 225 via an E2 link, or a Non-Real Time (Non-RT) RIC 215 associated with a Service Management and Orchestration (SMO) Framework 205, or both) . A CU 210 may communicate with one or more distributed units (DUs) 230 via respective midhaul links, such as an F1 interface. The DUs 230 may communicate with one or more radio units (RUs) 240 via respective fronthaul links. The RUs 240 may communicate with respective UEs 104 via one or more radio frequency (RF) access links. In some implementations, the UE 104 may be simultaneously served by multiple RUs 240.

Each of the units, e.g., the CUs 210, the DUs 230, the RUs 240, as well as the Near-RT RICs 225, the Non-RT RICs 215 and the SMO Framework 205, may include one or more interfaces or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller providing instructions to the communications interfaces of the units, can be configured to communicate with one or more of the other units via the transmission medium. For example, the units can include a wired interface configured to receive or transmit signals over a wired transmission medium to one or more of the other units. Additionally or alternatively, the units can include a wireless interface, which may include a receiver, a transmitter or transceiver (such as a radio frequency (RF) transceiver) , configured to receive or transmit signals, or both, over a wireless transmission medium to one or more of the other units.

In some aspects, the CU 210 may host one or more higher layer control functions. Such control functions can include radio resource control (RRC) , packet data convergence protocol (PDCP) , service data adaptation protocol (SDAP) , or the like. Each control function can be implemented with an interface configured to communicate signals with other control functions hosted by the CU 210. The CU 210 may be configured to handle user plane functionality (e.g., Central Unit –User Plane (CU-UP) ) , control plane functionality (e.g., Central Unit –Control Plane (CU-CP) ) , or a combination thereof. In some implementations, the CU 210 can be logically split into one or more CU-UP units and one or more CU-CP units. The CU-UP unit can communicate bidirectionally with the CU-CP unit via an interface, such as the E1 interface when implemented in an O-RAN configuration. The CU 210 can be implemented to communicate with the DU 230, as necessary, for network control and signaling.

The DU 230 may correspond to a logical unit that includes one or more base station functions to control the operation of one or more RUs 240. In some aspects, the DU 230 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, or the like) depending, at least in part, on a functional split, such as those defined by the 3^rd Generation Partnership Project (3GPP) . In some aspects, the DU 230 may further host one or more low PHY layers. Each layer (or module) can be implemented with an interface configured to communicate signals with other layers (and modules) hosted by the DU 230, or with the control functions hosted by the CU 210.

Lower-layer functionality can be implemented by one or more RUs 240. In some deployments, an RU 240, controlled by a DU 230, may correspond to a logical node that hosts RF processing functions, or low-PHY layer functions (such as performing fast Fourier transform (FFT) , inverse FFT (iFFT) , digital beamforming, physical random access channel (PRACH) extraction and filtering, or the like) , or both, based at least in part on the functional split, such as a lower layer functional split. In such an architecture, the RU (s) 240 can be implemented to handle over the air (OTA) communications with one or more UEs 104. In some implementations, real-time and non-real-time aspects of control and user plane communications with the RU (s) 240 can be controlled by the corresponding DU 230. In some scenarios, this configuration can enable the DU (s) 230 and the CU 210 to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

The SMO Framework 205 may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO Framework 205 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements which may be managed via an operations and maintenance interface (such as an O1 interface) . For virtualized network elements, the SMO Framework 205 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 290) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an O2 interface) . Such virtualized network elements can include, but are not limited to, CUs 210, DUs 230, RUs 240 and Near-RT RICs 225. In some implementations, the SMO Framework 205 can communicate with a hardware aspect of a 4G RAN, such as an open eNB (O-eNB) 211, via an O1 interface. Additionally, in some implementations, the SMO Framework 205 can communicate directly with one or more RUs 240 via an O1 interface. The SMO Framework 205 also may include a Non-RT RIC 215 configured to support functionality of the SMO Framework 205.

The Non-RT RIC 215 may be configured to include a logical function that enables non-real-time control and optimization of RAN elements and resources, Artificial Intelligence/Machine Learning (AI/ML) workflows including model training and updates, or policy-based guidance of applications/features in the Near-RT RIC 225. The Non-RT RIC 215 may be coupled to or communicate with (such as via an A1 interface) the Near-RT RIC 225. The Near-RT RIC 225 may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (such as via an E2 interface) connecting one or more CUs 210, one or more DUs 230, or both, as well as an O-eNB, with the Near-RT RIC 225.

In some implementations, to generate AI/ML models to be deployed in the Near-RT RIC 225, the Non-RT RIC 215 may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC 225 and may be received at the SMO Framework 205 or the Non-RT RIC 215 from non-network data sources or from network functions. In some examples, the Non-RT RIC 215 or the Near-RT RIC 225 may be configured to tune RAN behavior or performance. For example, the Non-RT RIC 215 may monitor long-term trends and patterns for performance and employ AI/ML models to perform corrective actions through the SMO Framework 205 (such as reconfiguration via O1) or via creation of RAN management policies (such as A1 policies) .

FIG. 3 depicts aspects of an example BS 102 and a UE 104.

Generally, BS 102 includes various processors (e.g., 320, 330, 338, and 340) , antennas 334a-t (collectively 334) , transceivers 332a-t (collectively 332) , which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., data source 312) and wireless reception of data (e.g., data sink 339) . For example, BS 102 may send and receive data between BS 102 and UE 104. BS 102 includes controller/processor 340, which may be configured to implement various functions described herein related to wireless communications.

Generally, UE 104 includes various processors (e.g., 358, 364, 366, and 380) , antennas 352a-r (collectively 352) , transceivers 354a-r (collectively 354) , which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., retrieved from data source 362) and wireless reception of data (e.g., provided to data sink 360) . UE 104 includes controller/processor 380, which may be configured to implement various functions described herein related to wireless communications.

In regards to an example downlink transmission, BS 102 includes a transmit processor 320 that may receive data from a data source 312 and control information from a controller/processor 340. The control information may be for the physical broadcast channel (PBCH) , physical control format indicator channel (PCFICH) , physical HARQ indicator channel (PHICH) , physical downlink control channel (PDCCH) , group common PDCCH (GC PDCCH) , and/or others. The data may be for the physical downlink shared channel (PDSCH) , in some examples.

Transmit processor 320 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. Transmit processor 320 may also generate reference symbols, such as for the primary synchronization signal (PSS) , secondary synchronization signal (SSS) , PBCH demodulation reference signal (DMRS) , and channel state information reference signal (CSI-RS) .

Transmit (TX) multiple-input multiple-output (MIMO) processor 330 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) in transceivers 332a-332t. Each modulator in transceivers 332a-332t may process a respective output symbol stream to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from the modulators in transceivers 332a-332t may be transmitted via the antennas 334a-334t, respectively.

In order to receive the downlink transmission, UE 104 includes antennas 352a-352r that may receive the downlink signals from the BS 102 and may provide received signals to the demodulators (DEMODs) in transceivers 354a-354r, respectively. Each demodulator in transceivers 354a-354r may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples to obtain received symbols.

MIMO detector 356 may obtain received symbols from all the demodulators in transceivers 354a-354r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. Receive processor 358 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 104 to a data sink 360, and provide decoded control information to a controller/processor 380.

In regards to an example uplink transmission, UE 104 further includes a transmit processor 364 that may receive and process data (e.g., for the PUSCH) from a data source 362 and control information (e.g., for the physical uplink control channel (PUCCH) ) from the controller/processor 380. Transmit processor 364 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS) ) . The symbols from the transmit processor 364 may be precoded by a TX MIMO processor 366 if applicable, further processed by the modulators in transceivers 354a-354r (e.g., for SC-FDM) , and transmitted to BS 102.

At BS 102, the uplink signals from UE 104 may be received by antennas 334a-t, processed by the demodulators in transceivers 332a-332t, detected by a MIMO detector 336 if applicable, and further processed by a receive processor 338 to obtain decoded data and control information sent by UE 104. Receive processor 338 may provide the decoded data to a data sink 339 and the decoded control information to the controller/processor 340.

Memories 342 and 382 may store data and program codes for BS 102 and UE 104, respectively.

Scheduler 344 may schedule UEs for data transmission on the downlink and/or uplink.

In various aspects, BS 102 may be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” may refer to various mechanisms of outputting data, such as outputting data from data source 312, scheduler 344, memory 342, transmit processor 320, controller/processor 340, TX MIMO processor 330, transceivers 332a-t, antenna 334a-t, and/or other aspects described herein. Similarly, “receiving” may refer to various mechanisms of obtaining data, such as obtaining data from antennas 334a-t, transceivers 332a-t, RX MIMO detector 336, controller/processor 340, receive processor 338, scheduler 344, memory 342, and/or other aspects described herein.

In various aspects, UE 104 may likewise be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” may refer to various mechanisms of outputting data, such as outputting data from data source 362, memory 382, transmit processor 364, controller/processor 380, TX MIMO processor 366, transceivers 354a-t, antenna 352a-t, and/or other aspects described herein. Similarly, “receiving” may refer to various mechanisms of obtaining data, such as obtaining data from antennas 352a-t, transceivers 354a-t, RX MIMO detector 356, controller/processor 380, receive processor 358, memory 382, and/or other aspects described herein.

In some aspects, a processor may be configured to perform various operations, such as those associated with the methods described herein, and transmit (output) to or receive (obtain) data from another interface that is configured to transmit or receive, respectively, the data.

FIGS. 4A, 4B, 4C, and 4D depict aspects of data structures for a wireless communications network, such as wireless communications network 100 of FIG. 1.

In particular, FIG. 4A is a diagram 400 illustrating an example of a first subframe within a 5G (e.g., 5G NR) frame structure, FIG. 4B is a diagram 430 illustrating an example of DL channels within a 5G subframe, FIG. 4C is a diagram 450 illustrating an example of a second subframe within a 5G frame structure, and FIG. 4D is a diagram 480 illustrating an example of UL channels within a 5G subframe.

Wireless communications systems may utilize orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on the uplink and downlink. Such systems may also support half-duplex operation using time division duplexing (TDD) . OFDM and single-carrier frequency division multiplexing (SC-FDM) partition the system bandwidth (e.g., as depicted in FIGS. 4B and 4D) into multiple orthogonal subcarriers. Each subcarrier may be modulated with data. Modulation symbols may be sent in the frequency domain with OFDM and/or in the time domain with SC-FDM.

A wireless communications frame structure may be frequency division duplex (FDD) , in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for either DL or UL. Wireless communications frame structures may also be time division duplex (TDD) , in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for both DL and UL.

In FIG. 4A and 4C, the wireless communications frame structure is TDD where D is DL, U is UL, and X is flexible for use between DL/UL. UEs may be configured with a slot format through a received slot format indicator (SFI) (dynamically through DL control information (DCI) , or semi-statically/statically through radio resource control (RRC) signaling) . In the depicted examples, a 10 ms frame is divided into 10 equally sized 1 ms subframes. Each subframe may include one or more time slots. In some examples, each slot may include 7 or 14 symbols, depending on the slot format. Subframes may also include mini-slots, which generally have fewer symbols than an entire slot. Other wireless communications technologies may have a different frame structure and/or different channels.

In certain aspects, the number of slots within a subframe is based on a slot configuration and a numerology. For example, for slot configuration 0, different numerologies (μ) 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology μ, there are 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2^μ×15 kHz, where μ is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing. FIGS. 4A, 4B, 4C, and 4D provide an example of slot configuration 0 with 14 symbols per slot and numerology μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

As depicted in FIGS. 4A, 4B, 4C, and 4D, a resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs) ) that extends, for example, 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs) . The number of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 4A, some of the REs carry reference (pilot) signals (RS) for a UE (e.g., UE 104 of FIGS. 1 and 3) . The RS may include demodulation RS (DMRS) and/or channel state information reference signals (CSI-RS) for channel estimation at the UE.The RS may also include beam measurement RS (BRS) , beam refinement RS (BRRS) , and/or phase tracking RS (PT-RS) .

FIG. 4B illustrates an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs) , each CCE including, for example, nine RE groups (REGs) , each REG including, for example, four consecutive REs in an OFDM symbol.

A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE (e.g., 104 of FIGS. 1 and 3) to determine subframe/symbol timing and a physical layer identity.

A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing.

Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI) . Based on the PCI, the UE can determine the locations of the aforementioned DMRS. The physical broadcast channel (PBCH) , which carries a master information block (MIB) , may be logically grouped with the PSS and SSS to form a synchronization signal (SS) /PBCH block. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN) . The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs) , and/or paging messages.

As illustrated in FIG. 4C, some of the REs carry DMRS (indicated as R for one particular configuration, but other DMRS configurations are possible) for channel estimation at the base station. The UE may transmit DMRS for the PUCCH and DMRS for the PUSCH. The PUSCH DMRS may be transmitted, for example, in the first one or two symbols of the PUSCH. The PUCCH DMRS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. UE 104 may transmit sounding reference signals (SRS) . The SRS may be transmitted, for example, in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

FIG. 4D illustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI) , such as scheduling requests, a channel quality indicator (CQI) , a precoding matrix indicator (PMI) , a rank indicator (RI) , and HARQ ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR) , a power headroom report (PHR) , and/or UCI.

Example UE to NW Relay

Aspects of the present disclosure involves a remote UE 104_REM, a relay UE 104_REL, and a network entity 102 (e.g., a gNB) , as shown in the example scenario 500 of FIG. 5. The example illustrates the following example connection paths: a Uu path (cellular link) between a relay UE and the network gNB, and a PC5 path (e.g., a device-to-device or D2D link) between the remote UE and the relay UE. In some aspects, the remote UE and the relay UE may be in radio resource control (RRC) connected mode.

As shown in FIGs. 6A, 6B, 7, and 8, a remote UE 104_REM may generally connect to a relay UE 104_REL via a layer 3 (L3) or layer 2 (L2) connection with no Uu connection with (and no visibility to) the network or via a layer 2 (L2) connection where the UE supports Uu access stratum (AS) and non-AS (NAS) connections with the network.

FIGs. 6A, 6B, 7, and 8are example block diagrams illustrating a control plane protocol stack on L3, for example, when there is no direct connection path (Uu connection) between the remote UE and the network node. In this situation, the remote UE does not have a Uu connection with a network and is connected to the relay UE via PC5 connection only (e.g., Layer 3 UE-to-NW) . The PC5 unicast link setup may, in some implementations, be needed for the relay UE to serve the remote UE. The remote UE may not have a Uu application server (AS) connection with a radio access network (RAN) over the relay path. In other cases, the remote UE may not have direct non-AS (NAS) connection with a 5G core network (5GC) . The relay UE may report to the 5GC about the remote UE’s presence. Alternatively and optionally, the remote UE may be visible to the 5GC via a non-3GPP interworking function (N3IWF) .

FIG. 7 and FIG. 8 are example block diagrams illustrating a control plane and user plane protocol stacks on L2, for example, when there is direct connection path between the remote UE 104_REM and the network node. This control plane protocol stack refers to an L2 relay option based on NR-V2X connectivity. Both PC5 control plane (C-plane) and the NR Uu C-plane are on the remote UE, similar to what is illustrated in FIG. 6. The PC5 C-plane may set up the unicast link before relaying. The remote UE may support the NR Uu AS and NAS connections above the PC5 radio link control (RLC) . The NG-RAN may control the remote UE’s PC5 link via NR radio resource control (RRC) . In some embodiments, an adaptation layer may be needed to support multiplexing multiple UEs’ traffic on the relay UE’s Uu connections.

As illustrated in FIG. 7 and FIG. 8, a layer 702, which may be referred to as a PC5 adaptation layer or a sidelink relay adaptation protocol (SRAP) layer may be used between a remote UE and a relay UE. This layer 702 may be different from a Uu Adaptation Layer. In some cases, while not shown in the figures, there may also be a PC5-S/PC5-RRC adaptation layer.

Certain systems, such as NR, may support standalone (SA) capability for sidelink-based UE-to-network and UE-to-UE relay communications, for example, utilizing layer-3 (L3) and layer-2 (L2) relays, as noted above.

Particular relay procedures may depend on whether a relay is a L3 relay or a L2 relay. In an L3 relay scenario, a remote UE establishes PC5-S unicast link setup and obtains an IP address. The PC5 unicast link AS configuration is managed using PC5-RRC. The relay UE and remote UE coordinate on the AS configuration. The relay UE may consider information from RAN to configure PC5 link. Authentication/authorization of the remote UE access to relaying may be done during PC5 link establishment. In the illustrated example, the relay UE performs L3 relaying.

In a L2 relay scenario, there may be no PC5 unicast link setup prior to relaying. The remote UE sends the NR RRC messages on PC5 signaling radio bearers (SRBs) over a sidelink broadcast control channel (SBCCH) . The RAN can indicate the PC5 AS configuration to remote UE and relay UE independently via NR RRC messages. Changes may be made to NR V2X PC5 stack operation to support radio bearer handling in NR RRC/PDCP but support corresponding logical channels in PC5 link. In L2 relaying, PC5 RLC may need to support interacting with NR PDCP directly.

Example Multi-Hop Relay Architecture and Protocol

As noted above, relay UEs may be used to extend coverage. However, current wireless systems that utilize relays for coverage extension may be limited to single-hop relays. In other words, as illustrated in the example scenario 900 of FIG. 9A, the data path between a remote UE 104_REM and the network includes only one single-hop relay UE 104_REL. As noted above, a hop generally refers to a number of entities (e.g., relay UEs) that a transmission passes through from its source to its destination.

Aspects of the present disclosure help support multi-hop relaying, which may help extend network or sidelink coverage via multiple relay UEs. As illustrated in the example multi-hop scenario 950 of FIG. 9B, the data path between a remote UE 104_REM and the network includes multiple relays, which may include a donor relay UE 104_DON and at least one intermediate relay UE 104_INT.

In this context, a donor relay UE generally refers to a relay UE which is in cellular (Uu) coverage. An intermediate relay UE generally refers to a relay UE between a remote UE and the donor relay UE.

Certain aspects of the present disclosure provide example architectures and protocols that may help enable and support multi-hop relaying. Mechanisms proposed herein may allow a UE to establish at least a first link with a first relay UE (e.g., an intermediate relay UE) and communicate with a network entity (e.g., a gNB) via the first relay UE and at least a second relay UE (e.g., a donor relay UE) . The communicating may involve exchanging packets with the first relay UE via the first link using a sidelink relay adaptation protocol (SRAP) layer at the remote UE.

According to certain aspects, multi-hop relaying is supported using independent hop link management. According to certain aspects, multi-hop relaying is supported using network controlled hop link management. According to certain aspects, multi-hop relaying is supported using combined Layer-2 and Layer-3 based relaying.

FIGs. 10 and 11 depict example call flow diagrams 1000 and 1100 for multi-hop relaying with independent hop link management, in accordance with aspects of the present disclosure.

FIG. 10 illustrates an example control plane protocol architecture for multi-hop relaying with independent hop link management. In the illustrated example, the remote UE 104_REM may be visible to the gNB (or other network entity) , while the intermediate relay UE 104_INT is not visible to the gNB.

In the illustrated example, there may be no RRC connection between the intermediate relay UE 104_INT and the gNB. In some cases, configuration for the intermediate relay UE 104_INT may be preconfigured or by PC5 message.

The donor relay UE 104_DON may be visible to the gNB as there may be an RRC connection between the donor relay UE 104_DON and the gNB. In some cases, Uu configuration for relay traffic may be provided by the gNB, while PC5 configuration may be preconfigured or provided via a PC5 message.

The remote UE 104_REM may be visible to the gNB. As shown, there may be an RRC connection between the remote UE 104_INT and the gNB. PC5 configuration for the remote UE 104_REM may be preconfigured or by PC5 message.

FIG. 11 illustrates an example user plane protocol architecture for multi-hop relaying with independent hop link management. In the illustrated example, the remote UE’s user plane traffic is relayed on each hop including a PC5 hop and a Uu hop.

The sidelink relay adaptation protocol (SRAP) layer may be a per-hop layer, in order to identify remote UE and end-to-end (E2E) bearers. Traffic from multiple E2E bearers can share one radio link control (RLC) channel (CH) configuration on each hop. Traffic from multiple remote UEs may share the PC5 link and RLC CH configuration on each hop.

FIG. 12 depicts an example call flow diagram 1200 for multi-hop relaying with network controlled hop link management, in accordance with aspects of the present disclosure. In the illustrated example, all of the relay UEs, including intermediate relay UE (s) 104_INT and donor relay UE 104_DON may be visible to the gNB.

In this case, intermediate relay UEs may effectively function as both remote UEs and relay UEs. For example, for the intermediate relay UE Uu RRC connection and user plane traffic, the intermediate relay UE may implement remote UE like functions, while the control plane and user plane traffic may be relayed by other intermediate relay UE (s) and the donor relay UE. For the remote UE traffic, the intermediate relay UE may implement relay UE like functions, forwarding the traffic between the remote UE and the gNB.

As illustrated, there may be an RRC connection between the intermediate relay UE/donor relay UE and the gNB. In some cases, both of the Uu and PC5 configurations on the intermediate relay UE/donor relay UE may be provided by the gNB using intermediate relay UE /donor relay UE RRC messaging. Uu and PC5 configuration on the remote UE may be provided by the gNB, for example, using the remote UE’s RRC messaging.

FIGs. 13 and 14 depict example call flow diagrams 1300 and 1400 for multi-hop relaying with combined Layer-2 and Layer-3 based relaying, in accordance with aspects of the present disclosure.

FIG. 13 illustrates an example control plane protocol architecture for multi-hop relaying with combined Layer-2 and Layer-3 based relaying.

As illustrated, a single-hop Layer-3 based U2N relay may be used between the remote UE and the network. In this case, the remote UE may have no Uu connection with the network, and may not be configured by the network.

As illustrated, a multi-hop Layer-2 based U2U relay may be used between the remote UE and the donor relay UE. In some cases, there may be an E2E PC5 connection between the remote UE and the donor relay UE. In such cases, a single-hop U2U E2E mechanism may be used. In some cases, the remote UE and the donor relay UE’s configuration and information on E2E PC5 used for Layer-3 based U2N relay may be transmitted using Layer-2 based U2U relaying between the Remote UE and the donor relay UE.

FIG. 14 illustrates an example control plane protocol architecture for multi-hop relaying with combined Layer-2 and Layer-3 based relaying.

In the illustrated example, remote UE user plane traffic, such as Internet Protocol (IP) packets, may be sent to the donor relay UE using Layer-2 based U2U relaying between the remote UE and the donor relay UE. The donor relay UE may transmit the Remote UE’s IP packets to a user plane function (UPF) , for example, using an existing Uu mechanism.

Example Operations

FIG. 15 shows an example of a method 1500 of wireless communications by a remote user equipment (UE) , such as a UE 104 of FIGS. 1 and 3.

Method 1500 begins at step 1505 with establishing at least a first link with a first relay UE. In some cases, the operations of this step refer to, or may be performed by, circuitry for establishing and/or code for establishing as described with reference to FIG. 18.

Method 1500 then proceeds to step 1510 with communicating with a network entity via the first relay UE and at least a second relay UE, wherein the communicating involves exchanging packets with the first relay UE via the first link using a sidelink relay adaptation protocol (SRAP) layer at the remote UE. In some cases, the operations of this step refer to, or may be performed by, circuitry for communicating and/or code for communicating as described with reference to FIG. 18.

In some aspects, the remote UE is visible to the network entity.

In some aspects, the packets comprise user plane traffic relayed via the first relay UE and the second relay UE.

In some aspects, each of the first relay UE and the second relay UE include a SRAP layer that identifies the remote UE and end to end (E2E) bearers for routing user plane traffic between the network entity and the remote UE.

In some aspects, at least one of: user traffic from multiple E2E bearers share a common radio link control (RLC) channel configuration on each of the first and second relay UEs; or traffic from multiple remote UEs share a sidelink interface and RLC channel configuration on each of the first and second relay UEs.

In some aspects, each of the first relay UE and the second relay UE is visible to the network entity.

In some aspects, the packets comprise control plane and user plane traffic relayed between the UE and network entity via the first relay UE and the second relay UE.

In some aspects, the method 1500 further includes receiving radio resource control (RRC) signaling indicating a configuration for the remote UE of at least one of a sidelink interface or a cellular interface. In some cases, the operations of this step refer to, or may be performed by, circuitry for receiving and/or code for receiving as described with reference to FIG. 18.

In some aspects, the communicating involves: at least one single hop relay path associated with a first protocol stack layer; and at least one multi-hop relay path associated with a second protocol stack layer.

In some aspects, the communicating involves an end-to-end sidelink interface connection between the remote UE and the second relay UE; and configuration for the end-to-end sidelink interface connection used for the single hop relay path is conveyed via the multi-hop relay path.

In some aspects, the communicating involves transmitting packets with user plane traffic of the remote UE to the first relay UE using the second protocol stack layer.

In some aspects, the first relay UE transmits packets with the user plane traffic of the remote UE to the second relay UE via a sidelink interface, for transmission to the network entity via a cellular interface.

In one aspect, method 1500, or any aspect related to it, may be performed by an apparatus, such as communications device 1800 of FIG. 18, which includes various components operable, configured, or adapted to perform the method 1500. Communications device 1800 is described below in further detail.

Note that FIG. 15 is just one example of a method, and other methods including fewer, additional, or alternative steps are possible consistent with this disclosure.

FIG. 16 shows an example of a method 1600 of wireless communications by a first relay user equipment (UE) , such as a UE 104 of FIGS. 1 and 3.

Method 1600 begins at step 1605 with establishing at least a first link with a remote UE. In some cases, the operations of this step refer to, or may be performed by, circuitry for establishing and/or code for establishing as described with reference to FIG. 18.

Method 1600 then proceeds to step 1610 with establishing at least a second link with a second relay UE. In some cases, the operations of this step refer to, or may be performed by, circuitry for establishing and/or code for establishing as described with reference to FIG. 18.

Method 1600 then proceeds to step 1615 with relaying packets between the remote UE and the second relay UE using a sidelink relay adaptation protocol (SRAP) layer at the first relay UE. In some cases, the operations of this step refer to, or may be performed by, circuitry for relaying and/or code for relaying as described with reference to FIG. 18.

In some aspects, the remote UE is visible to a network entity.

In some aspects, each of the first relay UE and the second relay UE is visible to a network entity.

In some aspects, the relaying involves: at least one single hop relay path associated with a first protocol stack layer; and at least one multi-hop relay path associated with a second protocol stack layer.

In some aspects, the relaying involves receiving packets with user plane traffic of the remote UE from the remote UE using the second protocol stack layer.

In some aspects, the first relay UE transmits packets with the user plane traffic of the remote UE to the second relay UE via a sidelink interface, for transmission to a network entity via a cellular interface.

In one aspect, method 1600, or any aspect related to it, may be performed by an apparatus, such as communications device 1800 of FIG. 18, which includes various components operable, configured, or adapted to perform the method 1600. Communications device 1800 is described below in further detail.

Note that FIG. 16 is just one example of a method, and other methods including fewer, additional, or alternative steps are possible consistent with this disclosure.

FIG. 17 shows an example of a method 1700 of wireless communications by a second relay user equipment (UE) , such as a UE 104 of FIGS. 1 and 3.

Method 1700 begins at step 1705 with establishing at least a first link with a network entity. In some cases, the operations of this step refer to, or may be performed by, circuitry for establishing and/or code for establishing as described with reference to FIG. 18.

Method 1700 then proceeds to step 1710 with establishing at least a second link with a first relay UE. In some cases, the operations of this step refer to, or may be performed by, circuitry for establishing and/or code for establishing as described with reference to FIG. 18.

Method 1700 then proceeds to step 1715 with relaying packets between the network entity and a remote UE via the second relay UE using a sidelink relay adaptation protocol (SRAP) layer at the second relay UE. In some cases, the operations of this step refer to, or may be performed by, circuitry for relaying and/or code for relaying as described with reference to FIG. 18.

In some aspects, the remote UE is visible to the network entity.

In some aspects, the relaying involves receiving packets with user plane traffic of the remote UE from the first relay UE using the second protocol stack layer.

In some aspects, the method 1700 further includes receiving packets with the user plane traffic of the remote UE from the first relay UE via a sidelink interface. In some cases, the operations of this step refer to, or may be performed by, circuitry for receiving and/or code for receiving as described with reference to FIG. 18.

In some aspects, the method 1700 further includes transmitting the packets with the user plane traffic to the network entity via a cellular interface. In some cases, the operations of this step refer to, or may be performed by, circuitry for transmitting and/or code for transmitting as described with reference to FIG. 18.

In one aspect, method 1700, or any aspect related to it, may be performed by an apparatus, such as communications device 1800 of FIG. 18, which includes various components operable, configured, or adapted to perform the method 1700. Communications device 1800 is described below in further detail.

Note that FIG. 17 is just one example of a method, and other methods including fewer, additional, or alternative steps are possible consistent with this disclosure.

Example Communications Device (s)

FIG. 18 depicts aspects of an example communications device 1800. In some aspects, communications device 1800 is a user equipment, such as UE 104 described above with respect to FIGS. 1 and 3.

The communications device 1800 includes a processing system 1805 coupled to the transceiver 1875 (e.g., a transmitter and/or a receiver) . The transceiver 1875 is configured to transmit and receive signals for the communications device 1800 via the antenna 1880, such as the various signals as described herein. The processing system 1805 may be configured to perform processing functions for the communications device 1800, including processing signals received and/or to be transmitted by the communications device 1800.

The processing system 1805 includes one or more processors 1810. In various aspects, the one or more processors 1810 may be representative of one or more of receive processor 358, transmit processor 364, TX MIMO processor 366, and/or controller/processor 380, as described with respect to FIG. 3. The one or more processors 1810 are coupled to a computer-readable medium/memory 1840 via a bus 1870. In certain aspects, the computer-readable medium/memory 1840 is configured to store instructions (e.g., computer-executable code) that when executed by the one or more processors 1810, cause the one or more processors 1810 to perform the method 1500 described with respect to FIG. 15, or any aspect related to it; the method 1600 described with respect to FIG. 16, or any aspect related to it; and the method 1700 described with respect to FIG. 17, or any aspect related to it. Note that reference to a processor performing a function of communications device 1800 may include one or more processors 1810 performing that function of communications device 1800.

In the depicted example, computer-readable medium/memory 1840 stores code (e.g., executable instructions) , such as code for establishing 1845, code for communicating 1850, code for receiving 1855, code for relaying 1860, and code for transmitting 1865. Processing of the code for establishing 1845, code for communicating 1850, code for receiving 1855, code for relaying 1860, and code for transmitting 1865 may cause the communications device 1800 to perform the method 1500 described with respect to FIG. 15, or any aspect related to it; the method 1600 described with respect to FIG. 16, or any aspect related to it; and the method 1700 described with respect to FIG. 17, or any aspect related to it.

The one or more processors 1810 include circuitry configured to implement (e.g., execute) the code stored in the computer-readable medium/memory 1840, including circuitry such as circuitry for establishing 1815, circuitry for communicating 1820, circuitry for receiving 1825, circuitry for relaying 1830, and circuitry for transmitting 1835. Processing with circuitry for establishing 1815, circuitry for communicating 1820, circuitry for receiving 1825, circuitry for relaying 1830, and circuitry for transmitting 1835 may cause the communications device 1800 to perform the method 1500 described with respect to FIG. 15, or any aspect related to it; the method 1600 described with respect to FIG. 16, or any aspect related to it; and the method 1700 described with respect to FIG. 17, or any aspect related to it.

Various components of the communications device 1800 may provide means for performing the method 1500 described with respect to FIG. 15, or any aspect related to it; the method 1600 described with respect to FIG. 16, or any aspect related to it; and the method 1700 described with respect to FIG. 17, or any aspect related to it. For example, means for transmitting, sending or outputting for transmission may include transceivers 354 and/or antenna (s) 352 of the UE 104 illustrated in FIG. 3 and/or the transceiver 1875 and the antenna 1880 of the communications device 1800 in FIG. 18. Means for receiving or obtaining may include transceivers 354 and/or antenna (s) 352 of the UE 104 illustrated in FIG. 3 and/or the transceiver 1875 and the antenna 1880 of the communications device 1800 in FIG. 18.

Example Clauses

Implementation examples are described in the following numbered clauses:

Clause 1: A method for wireless communications by a remote user equipment (UE) , comprising: establishing at least a first link with a first relay UE; and communicating with a network entity via the first relay UE and at least a second relay UE, wherein the communicating involves exchanging packets with the first relay UE via the first link using a sidelink relay adaptation protocol (SRAP) layer at the remote UE.

Clause 2: The method of Clause 1, wherein the remote UE is visible to the network entity.

Clause 3: The method of Clause 2, wherein the packets comprise user plane traffic relayed via the first relay UE and the second relay UE.

Clause 4: The method of Clause 3, wherein each of the first relay UE and the second relay UE include a SRAP layer that identifies the remote UE and end to end (E2E) bearers for routing user plane traffic between the network entity and the remote UE.

Clause 5: The method of Clause 4, wherein at least one of: user traffic from multiple E2E bearers share a common radio link control (RLC) channel configuration on each of the first and second relay UEs; or traffic from multiple remote UEs share a sidelink interface and RLC channel configuration on each of the first and second relay UEs.

Clause 6: The method of any one of Clauses 1-5, wherein each of the first relay UE and the second relay UE is visible to the network entity.

Clause 7: The method of Clause 6, wherein the packets comprise control plane and user plane traffic relayed between the UE and network entity via the first relay UE and the second relay UE.

Clause 8: The method of Clause 6, further comprising receiving radio resource control (RRC) signaling indicating a configuration for the remote UE of at least one of a sidelink interface or a cellular interface.

Clause 9: The method of any one of Clauses 1-8, wherein the communicating involves: at least one single hop relay path associated with a first protocol stack layer; and at least one multi-hop relay path associated with a second protocol stack layer.

Clause 10: The method of Clause 9, wherein: the communicating involves an end-to-end sidelink interface connection between the remote UE and the second relay UE; and configuration for the end-to-end sidelink interface connection used for the single hop relay path is conveyed via the multi-hop relay path.

Clause 11: The method of Clause 9, wherein the communicating involves transmitting packets with user plane traffic of the remote UE to the first relay UE using the second protocol stack layer.

Clause 12: The method of Clause 11, wherein the first relay UE transmits packets with the user plane traffic of the remote UE to the second relay UE via a sidelink interface, for transmission to the network entity via a cellular interface.

Clause 13: A method for wireless communications by a first relay user equipment (UE) , comprising: establishing at least a first link with a remote UE; establishing at least a second link with a second relay UE; and relaying packets between the remote UE and the second relay UE using a sidelink relay adaptation protocol (SRAP) layer at the first relay UE.

Clause 14: The method of Clause 13, wherein the remote UE is visible to a network entity.

Clause 15: The method of Clause 14, wherein the packets comprise user plane traffic relayed via the first relay UE and the second relay UE.

Clause 16: The method of Clause 15, wherein each of the first relay UE and the second relay UE include a SRAP layer that identifies the remote UE and end to end (E2E) bearers for routing user plane traffic between the network entity and the remote UE.

Clause 17: The method of Clause 16, wherein at least one of: user traffic from multiple E2E bearers share a common radio link control (RLC) channel configuration on each of the first and second relay UEs; or traffic from multiple remote UEs share a sidelink interface and RLC channel configuration on each of the first and second relay UEs.

Clause 18: The method of any one of Clauses 13-17, wherein each of the first relay UE and the second relay UE is visible to a network entity.

Clause 19: The method of Clause 18, wherein the packets comprise control plane and user plane traffic relayed between the UE and network entity via the first relay UE and the second relay UE.

Clause 20: The method of any one of Clauses 13-19, wherein the relaying involves: at least one single hop relay path associated with a first protocol stack layer; and at least one multi-hop relay path associated with a second protocol stack layer.

Clause 21: The method of Clause 20, wherein the relaying involves receiving packets with user plane traffic of the remote UE from the remote UE using the second protocol stack layer.

Clause 22: The method of Clause 21, wherein the first relay UE transmits packets with the user plane traffic of the remote UE to the second relay UE via a sidelink interface, for transmission to a network entity via a cellular interface.

Clause 23: A method for wireless communications by a second relay user equipment (UE) , comprising: establishing at least a first link with a network entity; establishing at least a second link with a first relay UE; and relaying packets between the network entity and a remote UE via the second relay UE using a sidelink relay adaptation protocol (SRAP) layer at the second relay UE.

Clause 24: The method of Clause 23, wherein the remote UE is visible to the network entity.

Clause 25: The method of Clause 24, wherein the packets comprise user plane traffic relayed via the first relay UE and the second relay UE.

Clause 26: The method of Clause 25, wherein each of the first relay UE and the second relay UE include a SRAP layer that identifies the remote UE and end to end (E2E) bearers for routing user plane traffic between the network entity and the remote UE.

Clause 27: The method of Clause 26, wherein at least one of: user traffic from multiple E2E bearers share a common radio link control (RLC) channel configuration on each of the first and second relay UEs; or traffic from multiple remote UEs share a sidelink interface and RLC channel configuration on each of the first and second relay UEs.

Clause 28: The method of any one of Clauses 23-27, wherein each of the first relay UE and the second relay UE is visible to the network entity.

Clause 29: The method of Clause 28, wherein the packets comprise control plane and user plane traffic relayed between the UE and network entity via the first relay UE and the second relay UE.

Clause 30: The method of any one of Clauses 23-29, wherein the relaying involves: at least one single hop relay path associated with a first protocol stack layer; and at least one multi-hop relay path associated with a second protocol stack layer.

Clause 31: The method of Clause 30, wherein the relaying involves receiving packets with user plane traffic of the remote UE from the first relay UE using the second protocol stack layer.

Clause 32: The method of Clause 31, further comprising: receiving packets with the user plane traffic of the remote UE from the first relay UE via a sidelink interface; and transmitting the packets with the user plane traffic to the network entity via a cellular interface.

Clause 33: An apparatus, comprising: a memory comprising executable instructions; and a processor configured to execute the executable instructions and cause the apparatus to perform a method in accordance with any one of Clauses 1-32.

Clause 34: An apparatus, comprising means for performing a method in accordance with any one of Clauses 1-32.

Clause 35: A non-transitory computer-readable medium comprising executable instructions that, when executed by a processor of an apparatus, cause the apparatus to perform a method in accordance with any one of Clauses 1-32.

Clause 36: A computer program product embodied on a computer-readable storage medium comprising code for performing a method in accordance with any one of Clauses 1-32.

Additional Considerations

The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein are not limiting of the scope, applicability, or aspects set forth in the claims. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. For example, changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various actions may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an ASIC, a field programmable gate array (FPGA) or other programmable logic device (PLD) , discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, a system on a chip (SoC) , or any other such configuration.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure) , ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information) , accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The methods disclosed herein comprise one or more actions for achieving the methods. The method actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of actions is specified, the order and/or use of specific actions may be modified without departing from the scope of the claims. Further, the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component (s) and/or module (s) , including, but not limited to a circuit, an application specific integrated circuit (ASIC) , or processor.

The following claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims. Within a claim, reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” refers to one or more. No claim element is to be construed under the provisions of 35 U. S. C. §112 (f) unless the element is expressly recited using the phrase “means for” . All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

Claims

An apparatus for wireless communication at a remote user equipment (UE) , comprising: at least one memory comprising computer-executable instructions; and one or more processors configured to execute the computer-executable instructions and cause the apparatus to:

establish at least a first link with a first relay UE; and

communicate with a network entity via the first relay UE and at least a second relay UE, wherein the communicating involves exchanging packets with the first relay UE via the first link using a sidelink relay adaptation protocol (SRAP) layer at the remote UE.
The apparatus of claim 1, wherein the remote UE is visible to the network entity.
The apparatus of claim 2, wherein the packets comprise user plane traffic relayed via the first relay UE and the second relay UE.
The apparatus of claim 3, wherein each of the first relay UE and the second relay UE include a SRAP layer that identifies the remote UE and end to end (E2E) bearers for routing user plane traffic between the network entity and the remote UE.
The apparatus of claim 4, wherein at least one of: user traffic from multiple E2E bearers share a common radio link control (RLC) channel configuration on each of the first and second relay UEs; or traffic from multiple remote UEs share a sidelink interface and RLC channel configuration on each of the first and second relay UEs.
The apparatus of claim 1, wherein each of the first relay UE and the second relay UE is visible to the network entity.
The apparatus of claim 6, wherein the packets comprise control plane and user plane traffic relayed between the UE and network entity via the first relay UE and the second relay UE.
The apparatus of claim 6, wherein the one or more processors are further configured to execute the computer-executable instructions and cause the apparatus to:

receive radio resource control (RRC) signaling indicating a configuration for the remote UE of at least one of a sidelink interface or a cellular interface.
The apparatus of claim 1, wherein the communicating involves:

at least one single hop relay path associated with a first protocol stack layer; and

at least one multi-hop relay path associated with a second protocol stack layer.
The apparatus of claim 9, wherein:

the communicating involves an end-to-end sidelink interface connection between the remote UE and the second relay UE; and

configuration for the end-to-end sidelink interface connection used for the single hop relay path is conveyed via the multi-hop relay path.
The apparatus of claim 9, wherein the communicating involves transmitting packets with user plane traffic of the remote UE to the first relay UE using the second protocol stack layer.
The apparatus of claim 11, wherein the first relay UE transmits packets with the user plane traffic of the remote UE to the second relay UE via a sidelink interface, for transmission to the network entity via a cellular interface.
An apparatus for wireless communication at a first relay user equipment (UE) , comprising: at least one memory comprising computer-executable instructions; and one or more processors configured to execute the computer-executable instructions and cause the apparatus to:

establish at least a first link with a remote UE;

establish at least a second link with a second relay UE; and

relay packets between the remote UE and the second relay UE using a sidelink relay adaptation protocol (SRAP) layer at the first relay UE.
The apparatus of claim 13, wherein the remote UE is visible to a network entity.
The apparatus of claim 14, wherein the packets comprise user plane traffic relayed via the first relay UE and the second relay UE.
The apparatus of claim 15, wherein each of the first relay UE and the second relay UE include a SRAP layer that identifies the remote UE and end to end (E2E) bearers for routing user plane traffic between the network entity and the remote UE.
The apparatus of claim 16, wherein at least one of:

user traffic from multiple E2E bearers share a common radio link control (RLC) channel configuration on each of the first and second relay UEs; or

traffic from multiple remote UEs share a sidelink interface and RLC channel configuration on each of the first and second relay UEs.
The apparatus of claim 13, wherein each of the first relay UE and the second relay UE is visible to a network entity.
The apparatus of claim 18, wherein the packets comprise control plane and user plane traffic relayed between the UE and network entity via the first relay UE and the second relay UE.
The apparatus of claim 13, wherein the relaying involves:

at least one single hop relay path associated with a first protocol stack layer; and

at least one multi-hop relay path associated with a second protocol stack layer.
The apparatus of claim 20, wherein the relaying involves receiving packets with user plane traffic of the remote UE from the remote UE using the second protocol stack layer.
The apparatus of claim 21, wherein the one or more processors are further configured to execute the computer-executable instructions and cause the apparatus to: transmit packets with the user plane traffic of the remote UE to the second relay UE via a sidelink interface, for transmission to a network entity via a cellular interface.
An apparatus for wireless communication at a second relay user equipment (UE) , comprising: at least one memory comprising computer-executable instructions; and one or more processors configured to execute the computer-executable instructions and cause the apparatus to:

establish at least a first link with a network entity;

establish at least a second link with a first relay UE; and

relay packets between the network entity and a remote UE via the second relay UE using a sidelink relay adaptation protocol (SRAP) layer at the second relay UE.
The apparatus of claim 23, wherein:

the remote UE is visible to the network entity, and

the packets comprise user plane traffic relayed via the first relay UE and the second relay UE.
The apparatus of claim 24, wherein each of the first relay UE and the second relay UE include a SRAP layer that identifies the remote UE and end to end (E2E) bearers for routing user plane traffic between the network entity and the remote UE, and at least one of:

user traffic from multiple E2E bearers share a common radio link control (RLC) channel configuration on each of the first and second relay UEs; or

traffic from multiple remote UEs share a sidelink interface and RLC channel configuration on each of the first and second relay UEs.
The apparatus of claim 23, wherein:

each of the first relay UE and the second relay UE is visible to the network entity, and

the packets comprise control plane and user plane traffic relayed between the UE and network entity via the first relay UE and the second relay UE.
The apparatus of claim 23, wherein the relaying involves: at least one single hop relay path associated with a first protocol stack layer; and at least one multi-hop relay path associated with a second protocol stack layer.
The apparatus of claim 27, wherein the relaying involves receiving packets with user plane traffic of the remote UE from the first relay UE using the second protocol stack layer.
The apparatus of claim 28, wherein the one or more processors are further configured to execute the computer-executable instructions and cause the apparatus to:

receive packets with the user plane traffic of the remote UE from the first relay UE via a sidelink interface; and

transmit the packets with the user plane traffic to the network entity via a cellular interface.
A method for wireless communications by a remote user equipment (UE) , comprising:

establishing at least a first link with a first relay UE; and

communicating with a network entity via the first relay UE and at least a second relay UE, wherein the communicating involves exchanging packets with the first relay UE via the first link using a sidelink relay adaptation protocol (SRAP) layer at the remote UE.