Method and apparatus for relay selection and reselection assisted by discovery information

Abstract

Certain aspects of the present disclosure provide techniques for relay selection and reselection based on discovery information. An example method generally includes: receiving relay selection assistance information from a network entity, the relay selection assistance information identifying a plurality of relay UEs available for selection by a UE; selecting a first relay UE among the plurality of relay UEs at least in part based on the relay selection assistance information; and connecting to the selected first relay UE via a sidelink.

Description

[0001] Public domain

[0002] Aspects of the present disclosure relate to wireless communication and, more particularly, to techniques for relay selection and reselection assisted by discovery information provided by a network.

[0003] Description of related technologies

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasting, etc. These wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access systems include Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, and Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, to name just a few examples.

[0005] In some examples, a wireless multiple access communication system may include a number of base stations (BSs), each capable of supporting communication with a plurality of communication devices (also referred to as user equipment (UE)) simultaneously. In an LTE or LTE-A network, a set including one or more base stations may define an evolved Node B (eNB). In other examples (e.g., in a next generation, New Radio (NR), or 5G network), a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with a number of central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set including one or more DUs in communication with a CU may define an access node (e.g., which may be referred to as a BS, 5G NB, next generation Node B (gNB or gNodeB), transmission reception point (TRP), etc.). A BS or DU may communicate with a set of UEs on a downlink channel (e.g., for transmission from the BS or DU to the UE) and an uplink channel (e.g., for transmission from the UE to the BS or DU).

[0006] These multiple access techniques have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at the urban, national, regional, and even global levels. NR (e.g., New Radio or 5G) is an example of an emerging telecommunication standard. NR is an enhanced set of the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by using OFDMA with cyclic prefix (CP) on the downlink (DL) and uplink (UL) to improve spectral efficiency, reduce costs, improve services, utilize new spectrum, and better integrate with other open standards. To this end, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

[0007] Sidelink communication is communication from one UE to another UE. As the demand for mobile broadband access continues to grow, there is a need for further improvements in NR and LTE technologies, including improvements to sidelink communication. Preferably, these improvements should be applicable to other multiple access techniques and the telecommunication standards that employ these techniques.

[0008] Brief Overview

[0009] The systems, methods, and devices of the present disclosure each have several aspects, and no single aspect is solely responsible for their desirable attributes. Without limiting the scope of the present disclosure as expressed by the appended claims, some features will now be briefly discussed. After considering this discussion, and particularly after reading the section entitled "Detailed Description," it will be understood how the features of the present disclosure provide advantages, including improved communication between an access point and a station in a wireless network.

[0010] Certain aspects provide a method for wireless communication by a remote user equipment (UE). The method generally includes receiving relay selection assistance information from a network entity, the relay selection assistance information identifying a plurality of relay UEs available for selection by the UE; selecting a first relay UE from the plurality of relay UEs at least partially based on the relay selection assistance information; and connecting to the selected first relay UE via a sidelink.

[0011] Certain aspects provide a method for wireless communication by a relay node. The method generally includes establishing a unicast connection with a remote UE via a sidelink; receiving, via the unicast connection, an indication to activate the unicast connection with the remote UE from the remote UE; and communicating with the UE via the unicast connection based on receiving the indication.

[0012] Certain aspects provide a method for wireless communication by a network entity. The method generally includes transmitting relay selection assistance information to a remote user equipment (UE), the relay selection assistance information identifying a plurality of relay UEs available for selection by the remote UE; and communicating with the remote UE via one of the plurality of relay UEs.

[0013] Aspects generally include methods, apparatuses, systems, computer-readable media, and processing systems substantially as described herein with reference to the figures and as illustrated by the figures.

[0014] To achieve the foregoing and related purposes, one or more of these aspects include the features described in detail below and particularly pointed out in the claims. The following description and the drawings set forth in detail certain illustrative features of one or more of these aspects. However, these features are only indicative of several ways in which the principles of the various aspects may be employed. Brief Description of the Drawings

[0016] To obtain a more particular description of the features briefly summarized above, reference may be made to the aspects, some of which are illustrated in the drawings. It should be noted, however, that the drawings illustrate only certain typical aspects of the present disclosure and are not to be considered limiting of its scope as the description may admit of other equally effective aspects.

[0017] Figure 1 is a block diagram conceptually illustrating an example telecommunications system in accordance with certain aspects of the present disclosure.

[0018] Figure 2 is a block diagram illustrating an example logical architecture of a distributed radio access network (RAN) in accordance with certain aspects of the present disclosure.

[0019] Figure 3 is a diagram illustrating an example physical architecture of a distributed RAN in accordance with certain aspects of the present disclosure.

[0020] Figure 4 is a block diagram conceptually illustrating the design of an example base station (BS) and user equipment (UE) in accordance with certain aspects of the present disclosure.

[0021] Figure 5 is a high-level path diagram illustrating an example connection path of a remote user equipment (UE) in accordance with certain aspects of the present disclosure.

[0022] Figure 6 is a block diagram illustrating an example control plane protocol stack at L3 when there is no direct connection path between a remote UE and a network node in accordance with certain aspects of the present disclosure.

[0023] Figure 7It is an example block diagram illustrating a control plane protocol stack at L2 when there is a direct connection path between a remote UE and a network node according to certain aspects of the present disclosure.

[0024] Figure 8 An example layer 3 (L3) relay procedure according to certain aspects of the present disclosure is illustrated.

[0025] Figure 9 An example layer 2 (L2) relay procedure according to certain aspects of the present disclosure is illustrated.

[0026] Figure 10A and 10B An example relay discovery procedure is illustrated.

[0027] Figure 11 An example communication environment is illustrated in which a relay UE serves one or more remote UEs.

[0028] Figure 12A and 12B An example scenario is illustrated in which a remote UE receives a paging and a system information block based on whether the remote UE is within or outside the coverage of a network entity.

[0029] Figure 13 An example connection path of a remote UE and paging before connecting to a relay are illustrated.

[0030] Figure 14 An example connection path between a remote UE and a relay after the remote UE connects to the relay is illustrated.

[0031] Figure 15 It is a flowchart illustrating example operations that can be performed by a remote UE according to certain aspects of the present disclosure.

[0032] Figure 16 It is a flowchart illustrating example operations that can be performed by a relay UE according to certain aspects of the present disclosure.

[0033] Figure 17 It is a flowchart illustrating example operations that can be performed by a network entity according to certain aspects of the present disclosure.

[0034] Figure 18 An example is illustrated of a communication device according to certain aspects of the present disclosure that can include various components configured to perform the operations illustrated in Figure 15 .

[0035] Figure 19 An example is illustrated of a communication device according to certain aspects of the present disclosure that can include various components configured to perform the operations illustrated in Figure 16 .

[0036] Figure 20A communication device is described that, in accordance with certain aspects of the present disclosure, may include various components configured to perform the operations illustrated in Figure 17 as illustrated.

[0037] To facilitate understanding, wherever possible, the same reference numerals have been used to designate identical elements common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized in other aspects without specific recitation.

[0038] Detailed Description

[0039] Aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for selecting and reselecting a relay UE in a sidelink layer 2 (L2) and / or layer 3 (L3) relay system based on discovery information.

[0040] The connection between the relay and the network entity may be referred to as a Uu connection or via a Uu path. The connection between the remote UE and the relay (e.g., another UE or “relay UE”) may be referred to as a PC5 connection or via a PC5 path. A PC5 connection is a device-to-device connection that can utilize the relatively close proximity between the remote UE and the relay UE (e.g., when the remote UE is closer to the relay UE than to the nearest base station). The relay UE may be connected to an infrastructure node (e.g., a gNB) via a Uu connection and relay the Uu connection to the remote UE via a PC5 connection.

[0041] The following description provides examples and is not intended to limit the scope, applicability, or examples set forth in the claims. Changes may be made to the functionality and arrangement of the elements discussed without departing from the scope of the present disclosure. Various examples may appropriately omit, substitute, or add various procedures or components. For example, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with reference to some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement an apparatus or practice a method. Additionally, the scope of the present disclosure is intended to cover such apparatus or methods practiced using other structures, functionality, or structures and functionality that supplement or are different from the aspects of the present disclosure set forth herein. It should be understood that any aspect of the present disclosure disclosed herein may be implemented by one or more elements of the claims. The term “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” need not be construed as superior or better than other aspects.

[0042] The techniques described herein can be used for various wireless communication technologies such as LTE, CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other networks. The terms "network" and "system" are often used interchangeably. CDMA networks may implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers the IS-2000, IS-95, and IS-856 standards. TDMA networks may implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks may implement radio technologies such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS).

[0043] New Radio (NR) is an emerging wireless communication technology being developed in conjunction with the 5G Technology Forum (5GTF). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are UMTS releases that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). The techniques described herein can be used for the wireless networks and radio technologies mentioned above and other wireless networks and radio technologies. For clarity, while aspects may be described herein using terms typically associated with 3G and / or 4G wireless technologies, aspects of the present disclosure can be applied in communication systems based on other generations including NR technology (such as 5G and later generations).

[0044] New Radio (NR) access (e.g., 5G technology) can support various wireless communication services such as enhanced mobile broadband (eMBB) targeted at wide bandwidths (e.g., 80 MHz or higher), millimeter wave (mmW) targeted at high carrier frequencies (e.g., 25 GHz or higher), massive machine type communication MTC (mMTC) targeted at non-backward compatible MTC technology, and / or mission critical targeted at ultra-reliable low latency communication (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet the corresponding quality of service (QoS) requirements. Additionally, these services can coexist in the same subframe.

[0045] Figure 1 An example wireless communication network 100 in which aspects of the present disclosure may be implemented is illustrated. For example, Figure 1 UE 120a and / or BS 110a may be configured to perform operations 1100, 1200, and 1300 for handling paged communications in a sidelink L2 relay scenario as described below with reference to Figure 15 , 16 and 17.

[0046] As Figure 1 illustrated, the wireless communication network 100 may include several base stations (BSs) 110a-z (each also individually referred to herein as BS 110 or collectively as BS 110) and other network entities. In aspects of the present disclosure, a roadside service unit (RSU) may be considered a type of BS, and BS 110 may be referred to as an RSU. BS 110 may provide communication coverage for a particular geographic area (sometimes referred to as a “cell”), which may be stationary or may move according to the location of the mobile BS 110. In some examples, BS 110s may be interconnected with each other and / or with one or more other BSs or network nodes (not shown) in the wireless communication network 100 using any suitable transport network via various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.). In the example shown in Figure 1 , BSs 110a, 110b, and 110c may be macro BSs for macrocells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for picocell 102x. BSs 110y and 110z may be femto BSs for femtocells 102y and 102z, respectively. A BS may support one or more cells. BS 110 communicates with user equipment (UE) 120a-y (each also individually referred to herein as UE 120 or collectively as UE 120) in the wireless communication network 100. UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless communication network 100, and each UE 120 may be stationary or mobile.

[0047] The wireless communication network 100 may also include a relay station (e.g., relay station 110r) (also referred to as a relay, etc.), which receives transmissions of data and / or other information from an upstream station (e.g., BS 110a or UE 120r) and transmits the data and / or other information to a downstream station (e.g., UE 120 or BS 110), or which relays transmissions between UEs 120 to facilitate communication between devices.

[0048] The network controller 130 can be coupled to a set of BSs 110 and provide coordination and control of these BSs 110. The network controller 130 can communicate with the BSs 110 via a backhaul. The BSs 110 can also communicate with each other via a wireless or wired backhaul (e.g., directly or indirectly).

[0049] UEs 120 (e.g., 120x, 120y, etc.) can be dispersed throughout the wireless communication network 100, and each UE can be stationary or mobile. A UE can also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a client premise equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, a superbook, an appliance, a medical device or equipment, a biometric sensor / device, a wearable device (such as a smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet, etc.)), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicle component or sensor, a smart meter / sensor, an industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium. Some UEs can be considered machine type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., which can communicate with a BS, another device (e.g., a remote device), or some other entity. A wireless node can provide connectivity to a network (e.g., a wide area network, such as the Internet or a cellular network) or provide connectivity to the network via a wired or wireless communication link. Some UEs can be considered Internet of Things (IoT) devices, which can be narrowband IoT (NB-IoT) devices.

[0050] Some wireless networks (e.g., LTE) utilize Orthogonal Frequency Division Multiplexing (OFDM) on the downlink and Single Carrier Frequency Division Multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, which are also often referred to as frequency tones, frequency bins, etc. Each subcarrier can be modulated with data. Generally, modulation symbols are transmitted in the frequency domain for OFDM and in the time domain for SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. For example, the subcarrier spacing can be 15 kHz, and the smallest resource allocation (referred to as a "resource block" (RB)) can be 12 subcarriers (or 180 kHz). Thus, for system bandwidths of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), the nominal Fast Fourier Transform (FFT) size can be equal to 128, 256, 512, 1024, or 2048, respectively. The system bandwidth can also be divided into subbands. For example, a subband can cover 1.08 MHz (i.e., 6 resource blocks), and for system bandwidths of 1.25, 2.5, 5, 10, or 20 MHz, there can be 1, 2, 4, 8, or 16 subbands, respectively.

[0051] While aspects of the examples described herein may be associated with LTE technology, aspects of the present disclosure may be applicable to other wireless communication systems such as NR. NR can utilize OFDM with CP on both the uplink and downlink and includes support for half-duplex operation using TDD. Beamforming can be supported and beam directions can be dynamically configured. MIMO transmission with precoding can also be supported. MIMO configurations in the DL can support up to 8 transmit antennas (multi-layer DL transmission with up to 8 streams) and up to 2 streams per UE. Multi-layer transmission with up to 2 streams per UE can be supported. Aggregation of multiple cells can be supported using up to 8 serving cells.

[0052] In some examples, access to the air interface can be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication among some or all of the devices and equipment within its service area or cell. The scheduling entity can be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for a scheduled communication, the subordinate entity utilizes the resources allocated by the scheduling entity. A base station is not the only entity that can serve as a scheduling entity. In some examples, a UE can act as a scheduling entity and can schedule resources for one or more subordinate entities (e.g., one or more other UEs), and the other UEs can utilize the resources scheduled by the UE for wireless communication. In some examples, a UE can act as a scheduling entity in a peer-to-peer (P2P) network and / or in a mesh network. In a mesh network example, UEs can communicate directly with each other in addition to communicating with the scheduling entity.

[0053] In Figure 1 it, the solid line with double arrows indicates the desired transmission between the UE and the serving BS, which is the BS designated to serve the UE on the downlink and / or uplink. The thin dashed line with double arrows indicates the interference transmission between the UE and the BS.

[0054] Figure 2 illustrates an example logical architecture of a distributed radio access network (RAN) 200, which can be implemented in the wireless communication network 100 illustrated in Figure 1 it. The 5G access node 206 may include an access node controller (ANC) 202. The ANC 202 may be a central unit (CU) of the distributed RAN 200. The backhaul interface to the next-generation core network (NG-CN) 204 may be terminated at the ANC 202. The backhaul interface to an adjacent next-generation access node (NG-AN) 210 may be terminated at the ANC 202. The ANC 202 may include one or more TRPs 208 (e.g., cells, BSs, gNBs, etc.).

[0055] The TRP 208 may be a distributed unit (DU). The TRP 208 may be connected to a single ANC (e.g., ANC 202) or more than one ANC (not illustrated). For example, for RAN sharing, radio as a service (RaaS), and service-specific AND deployments, the TRP 208 may be connected to more than one ANC. Each TRP 208 may include one or more antenna ports. The TRP 208 may be configured to serve traffic to the UE individually (e.g., dynamically select) or jointly (e.g., joint transmission).

[0056] The logical architecture of the distributed RAN 200 may support fronthaul solutions across different deployment types. For example, the logical architecture may be based on transport network capabilities (e.g., bandwidth, latency, and / or jitter).

[0057] The logical architecture of the distributed RAN 200 may share features and / or components with LTE. For example, the next-generation access node (NG-AN) 210 may support dual connectivity with NR and may share a common fronthaul for LTE and NR.

[0058] The logical architecture of the distributed RAN 200 may enable cooperation between and among the TRPs 208, e.g., within a TRP and / or across TRPs via the ANC 202. An inter-TRP interface may not be used.

[0059] The logical functions can be dynamically distributed in the logical architecture of the distributed RAN 200. The radio resource control (RRC) layer, packet data convergence protocol (PDCP) layer, radio link control (RLC) layer, media access control (MAC) layer, and physical (PHY) layer can be adaptively placed at the DU (e.g., TRP 208) or CU (e.g., ANC 202).

[0060] Figure 3 An example physical architecture of a distributed RAN 300 in accordance with aspects of the present disclosure is illustrated. A centralized core network unit (C-CU) 302 may host core network functions. The C-CU 302 may be centrally deployed. The C-CU 302 functionality may be offloaded (e.g., to an advanced wireless service (AWS)) to attempt to handle peak capacity.

[0061] A centralized RAN unit (C-RU) 304 may host one or more ANC functions. Optionally, the C-RU 304 may locally host core network functions. The C-RU 304 may have a distributed deployment. The C-RU 304 may be close to the network edge.

[0062] The DU 306 may host one or more TRPs (edge node (EN), edge unit (EU), radio head (RH), smart radio head (SRH), etc.). The DU may be located at the edge of the network with radio frequency (RF) functionality.

[0063] Figure 4 Illustrated are (as Figure 1 depicted in) example components of BS110a and UE 120a, which may be used to implement aspects of the present disclosure. For example, the antenna 452, processors 466, 458, 464, and / or controller / processor 480 of the UE 120a and / or the antenna 434, processors 420, 430, 438, and / or controller / processor 440 of the BS110a may be used to perform the various techniques and methods described herein with reference to Figure 15 、 16 and 17.

[0064] At BS110a, the transmit processor 420 may receive data from the data source 412 and control information from the controller / processor 440. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid ARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data may be for the physical downlink shared channel (PDSCH), etc. The processor 420 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor 420 may also generate reference symbols (e.g., primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal (CRS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 430 may perform spatial processing (e.g., precoding) on the data symbols, control symbols, and / or reference symbols, if applicable, and may provide the output symbol streams to the modulators (MOD) 432a through 432t. Each modulator 432 may process its respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator may further process the output sample stream (e.g., convert to analog, amplify, filter, and up-convert) to obtain a downlink signal. The downlink signals from the modulators 432a through 432t may be transmitted via the antennas 434a through 434t, respectively.

[0065] At UE 120a, the antennas 452a through 452r may receive the downlink signals from the base station 110a and may provide the received signals to the demodulators (DEMOD) 454a through 454r in the transceiver, respectively. Each demodulator 454 may condition (e.g., filter, amplify, down-convert, and digitize) its respective received signal to obtain an input sample. Each demodulator may further process the input sample (e.g., for OFDM, etc.) to obtain received symbols. The MIMO detector 456 may obtain the received symbols from all the demodulators 454a through 454r, perform MIMO detection on the received symbols, if applicable, and provide detected symbols. The receive processor 458 may process (e.g., demodulate, de-interleave, and decode) the detected symbols, provide the decoded data for UE 120a to the data sink 460, and provide the decoded control information to the controller / processor 480.

[0066] On the uplink, at the UE 120a, the transmit processor 464 may receive and process data from the data source 462 (e.g., for the physical uplink shared channel (PUSCH)) and control information from the controller / processor 480 (e.g., for the physical uplink control channel (PUCCH)). The transmit processor 464 may also generate reference symbols for reference signals (e.g., sounding reference signals (SRS)). The symbols from the transmit processor 464 may be precoded by the TX MIMO processor 466 when applicable, further processed by the demodulators 454a through 454r in the transceiver (e.g., for SC-FDM, etc.), and transmitted to the base station 110a. At the BS 110a, the uplink signals from the UE 120a may be received by the antenna 434, processed by the modulator 432, detected by the MIMO detector 436 when applicable, and further processed by the receive processor 438 to obtain the decoded data and control information transmitted by the UE 120a. The receive processor 438 may provide the decoded data to the data sink 439 and the decoded control information to the controller / processor 440.

[0067] The controller / processors 440 and 480 may direct operations at the BS 110a and the UE 120a, respectively. The processor 440 and / or other processors and modules at the BS 110a may execute or direct the execution of processes for the techniques described herein with reference to Figure 15 , 16 and 17.

[0068] In some cases, two or more lower-level entities (e.g., UEs) may communicate with each other using sidelink signals. Real-world applications of such sidelink communications may include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communication, Internet of Everything (IoE) communication, IoT communication, mission-critical mesh, and / or various other suitable applications. Generally, a sidelink signal may refer to a signal that is communicated from one lower-level entity (e.g., UE1) to another lower-level entity (e.g., UE2) without relaying the communication through a scheduling entity (e.g., a UE or a BS), even though the scheduling entity may be used for scheduling and / or control purposes. In some examples, sidelink signals may be communicated using licensed spectrum (different from wireless local area network (WLAN), which typically uses unlicensed spectrum).

[0069] Example UE-to-network (NW) relay

[0070] As Figure 5 shown, aspects of the present disclosure relate to remote UEs, relay UEs, and networks, Figure 5It is a high-level path diagram explaining the example connection path: the Uu path (cellular link) between the relay UE and the network gNB, and the PC5 path (D2D link) between the remote UE and the relay UE. The remote UE and the relay UE can be in the Radio Resource Control (RRC) connected mode.

[0071] As Figure 6 and Figure 7 shown, the remote UE can generally connect to the relay UE via a Layer 3 (L3) connection without a Uu connection to the network (and without visibility to the network), or via a Layer 2 (L2) connection in which the UE supports both Uu access stratum (AS) and non-AS connection (NAS) to the network.

[0072] Figure 6 It is an example block diagram explaining the control plane protocol stack on L3 when there is no direct connection path (Uu connection) between the remote UE and the network node. In this case, the remote UE does not have a Uu connection to the network and is only connected to the relay UE via a PC5 connection (e.g., Layer 3 UE to NW). In some implementations, the relay UE may require PC5 unicast link establishment to serve the remote UE. The remote UE may not have a Uu application server (AS) connection to the Radio Access Network (RAN) on the relay path. In other cases, the remote UE may not have a direct non-access stratum (NAS) connection to the 5G Core Network (5GC). The relay UE can report the presence of the remote UE to the 5GC. Alternatively and optionally, the remote UE can be visible to the 5GC via a non-3GPP Interworking Function (N3IWF).

[0073] Figure 7 It is an example block diagram explaining the control plane protocol stack on L2 when there is a direct connection path between the remote UE and the network node. This control plane protocol stack refers to the L2 relay option based on NR-V2X connectivity. Both the PC5 control plane (C-plane) and the NR Uu control plane are on the remote UE, similar to Figure 6 explained. The PC5 control plane can establish a unicast link before the relay. The remote UE can support NR Uu AS and NAS connections on top of PC5 Radio Link Control (RLC). The NG-RAN can control the PC5 link of the remote UE via NR Radio Resource Control (RRC). In some embodiments, an adaptation layer may be required to support multiplexing the traffic of multiple UEs on the Uu connection of the relay UE.

[0074] For example, using Layer 3 (L3) and Layer 2 (L2) relay, certain systems (such as NR) can support the self-standing (SA) ability for sidelink-based UE-to-network and UE-to-UE relay communication, as described above.

[0075] Specific relay procedures may depend on whether the relay is an L3 relay or an L2 relay. Figure 8 An example dedicated PDU session for an L3 relay is illustrated. In the scenario shown, the remote UE establishes a PC5-S unicast link setup and obtains an IP address. PC5-RRC is used to manage the PC5 unicast link AS configuration. The relay UE and the remote UE coordinate on the AS configuration. The relay UE may consider information from the RAN to configure the PC5 link. Authentication / authorization of the remote UE's access to the relay may be completed during the PC5 link establishment. In the illustrated example, the relay UE performs an L3 relay.

[0076] Figure 9 An example dedicated PDU session for an L2 relay is illustrated. In the scenario shown, there is no PC5 unicast link setup before the relay. The remote UE sends an NR RRC message on a PC5 signaling radio bearer (SRB) via the sidelink broadcast control channel (SBCCH). The RAN may independently indicate the PC5 AS configuration to the remote UE and the relay UE via the NR RRC message. Changes may be made to the NR V2X PC5 stack operation to support radio bearer handling in NR RRC / PDCP, but support the corresponding logical channels in the PC5 link. In an L2 relay, the PC5 RLC may need to support direct interaction with the NR PDCP.

[0077] The sidelink relay DRX scenario needs to address various issues. One issue involves supporting remote UE sidelink DRX for relay discovery. In some cases, one assumption for relay discovery is that the relay UE is only in the connected mode, rather than idle / inactive. The remote UE may be in the connected, idle / inactive, or out-of-coverage (OOC) mode.

[0078] Discovery for relay selection and reselection may be supported. Different types of discovery models may be supported. For example, a first model (referred to as Model A discovery) is shown in Figure 10A In this case, one UE sends a discovery message (announcement), while other UEs monitor. According to Figure 10B the second model (referred to as Model B discovery) shown, one UE (the discoverer) sends a solicitation message and waits for a response from the monitoring UE (the discovered). Such discovery messages may be sent on the PC5 communication channel (e.g., rather than on a separate discovery channel). The discovery message may be carried in the same layer 2 frame as those used for other direct communications, e.g., which includes a destination layer 2 ID that may be set to a unicast, multicast, or broadcast identifier, a source layer 2 ID that is always set to the unicast identifier of the transmitter, and a frame type indicating that the frame is a ProSe Direct Discovery message.

[0079] As described above, for relay selection, the remote UE is not yet connected to any relay node (i.e., no PC5 unicast link is established between the remote UE and the relay node). In this case, it may be desirable to design a DRX mode to reduce the power consumption of the remote UE while monitoring relay discovery messages for relay selection.

[0080] As described above, for relay reselection, the remote UE is already connected to at least one relay node (e.g., where a PC5 unicast has been established between the remote UE and the relay node). For relay reselection, it may be desirable to design a DRX configuration that helps reduce the power consumption of the remote UE while monitoring relay discovery messages and PC5 data transmission for relay reselection.

[0081] Figure 11 An example environment is illustrated in which the remote UE is served by a network entity via a UE-to-network relay (e.g., a relay UE). To communicate via the relay UE, a remote UE that is not yet connected to a relay node can discover relay nodes and select one or more relay nodes as relays for the remote UE. For example, the remote UE can discover all relay nodes having a sidelink discovery reference signal received power (SD-RSRP) higher than a first threshold (e.g., higher than q-Rx-LevMin by more than minHyst). When the remote UE has connected to a relay node, the remote UE can also reselect a relay. To do so, the remote UE can determine that the sidelink RSRP (SL-RSRP) is below a second threshold (e.g., lower than q-Rx-LevMin by more than minHyst) and, based on that determination, discover relay nodes having an SD-RSRP higher than the first threshold.

[0082] Example selection and reselection of relay UEs in a sidelink layer 2 and layer 3 relay system based on discovery information

[0083] Aspects of the present disclosure provide an apparatus, method, processing system, and computer-readable medium for selecting and reselecting a relay UE in a sidelink L2 and / or L3 relay system based on discovery information. As will be described, these techniques can enable a remote UE to quickly select and reselect a relay UE in response to a changed state of the network connection between the remote UE and the relay UE(s).

[0084] Figure 12A and Figure 12B An example scenario is illustrated in which the UE communicates with a network entity (e.g., a gNB). In Figure 12A and Figure 12B In the two scenarios illustrated, the relay UE is within coverage and is in one of the RRC idle, inactive, or connected states. In Figure 12AIn the scenario being described, the remote UE is within the coverage of a network entity. Since the remote UE is within the coverage, the remote UE can directly receive paging and System Information Blocks (SIBs) from the network entity via the Uu link. However, in Figure 12B the scenario being described, the remote UE can be outside the coverage of the network entity. Since the remote UE is outside the coverage and the relay UE is within the coverage, the remote UE can connect to the relay UE and receive paging and SIBs from the network entity via the relay UE.

[0085] Figure 13 An example of paging performed by the remote UE before connecting to the relay UE is illustrated. Before the remote UE connects to the relay UE, the UE can follow UE idle or inactive behavior as would be used when the remote UE is connected to the network entity. For example, the UE can perform idle mode measurements and cell selection (reselection). Upon receiving Uu paging from the network entity, the UE can trigger the establishment or restoration of Unified Access Control (UAC) and Radio Resource Configuration (RRC), and can monitor the Uu connection for SIB updates. A remote UE within the coverage of the network entity can receive paging from the network entity; however, a remote UE outside the coverage of the network entity and not connected to a relay within the coverage may not be able to receive paging and SIBs from the network entity.

[0086] Figure 14 An example of paging performed by the remote UE after connecting to the relay (e.g., after establishing a PC5 RRC connection) is illustrated. The remote UE can be configured by the gNB into one of multiple paging modes. In direct paging, the remote UE can monitor Uu paging and SIB updates. If no signaling indicating the paging mode to be used by the UE is received, direct paging can be the default mode applied by the remote UE. Forward paging can allow the remote UE to forgo monitoring Uu paging or SIB updates; instead, the relay UE monitors the paging of the remote UE and forwards the paging of the remote UE to the remote UE. Adaptive paging can allow switching between direct paging and forward paging based on a request from the remote UE. Finally, the remote UE can be configured into a no-paging mode, in which neither the remote UE nor the relay UE monitors Uu paging and / or SIB updates for the remote UE. Generally, the remote paging mode can be configured on a per-remote-UE basis, as Figure 4 illustrated. For example, remote UE 3 can directly monitor Uu paging, while remote UEs 1 and 2 connected to the relay UE can rely on paging forwarding.

[0087] Aspects of the present disclosure can allow a remote UE to select and reselect a relay UE in a sidelink L2 or L3 relay system based on discovery information. Figure 15 、 Figure 16 and Figure 17Example operations for selecting and reselecting a relay UE in a sidelink L2 or L3 relay system based on discovery information are explained from the perspectives of a remote UE, a relay UE, and a network entity, respectively.

[0088] Figure 15 Example operation 1500 that can be performed by a remote UE to select and reselect a relay UE in a sidelink L2 or L3 relay system based on discovery information is explained. As explained, operation 1500 begins at block 1502, where the remote UE receives relay selection assistance information from a network entity, and the relay selection assistance information identifies multiple relay UEs available for the UE to select.

[0089] At block 1504, the remote UE can select a first relay from the multiple relay UEs at least in part based on the relay selection assistance information.

[0090] At block 1506, the remote UE connects to the selected first relay UE via a sidelink.

[0091] Figure 16 Example operation 1600 that can be performed by a relay UE for a remote UE to perform fast selection and reselection based on discovery information is explained. As explained, operation 1600 can begin at block 1602, where the relay UE establishes a unicast connection with the remote UE via a sidelink.

[0092] At block 1604, the relay UE receives an indication from the remote UE to activate the unicast connection with the remote UE.

[0093] At block 1606, the relay UE communicates with the remote UE via the unicast connection based on receiving the indication.

[0094] Figure 17 Example operations that can be performed by a network entity to configure a remote UE to perform selection and reselection of a relay UE based on discovery information are explained. As explained, operation 1700 can begin at block 1702, where the network entity transmits relay selection assistance information to the remote UE, and the relay selection assistance information identifies multiple relay UEs available for the remote UE to select.

[0095] At block 1704, the network entity communicates with the remote UE via one of the multiple relay UEs.

[0096] Generally, aspects described herein assist a remote UE in performing relay UE selection or reselection based on assistance information that can be provided to the remote UE. The assistance information can help the UE select a relay UE. For example, by providing information about each available relay UE, the remote UE can use this information to include a relay UE in a list of candidate relay UEs to which the remote UE can connect or to exclude a relay UE from the list. Additionally, as discussed further below, the remote UE can use the assistance information to establish unicast connections with multiple relay UEs, which can allow the remote UE to quickly transition from communicating with one relay UE to communicating with another relay UE without waiting to establish a connection with the other relay UE.

[0097] Relay selection assistance information can be included in one or more of a discovery message, a dedicated message transmitted by a network entity during a discovery procedure, or a system information block (SIB) broadcast by a network entity to the remote UE (and other UEs in the network).

[0098] In some aspects, the assistance information can include L2 / L3 assistance information for UE-to-network relays. In such cases, the relay selection assistance information can be organized on a per-cell basis. The relay selection assistance information can include cell identifier information for each cell. The cell identifier information can include a cell ID, a physical cell ID (PCI) and the frequency carrying the PCI, a cell global identity (CGI), a tracking area identity (TAI), etc. In some aspects, the relay selection assistance information can include load information for each cell, which the UE can use to prefer a side-link connection to a cell with a lighter load over a side-link connection to a cell with a heavier load. In some aspects, the relay selection assistance information can include quality of service (QoS) information for the cell. The QoS information can include, for example, the minimum QoS supported by the relay Uu link (e.g., the link between the relay UE and the network entity) and / or the minimum QoS supported by the relay PC5 link (e.g., the link between the remote UE and the relay UE). In some aspects, the relay selection assistance information can include neighbor relay information, such as a list of relay UEs associated with the cell and the corresponding frequencies for measurement, and the connection status of the relay UEs. The relay selection assistance information can include public land mobile network information associated with the cell. In some aspects, the relay selection assistance information can include relay selection and reselection parameters for each cell. The relay selection and reselection parameters can include, for example, a minimum reference signal received power (RSRP) for a cell to be a candidate cell, a minimum hysteresis value, a side-link RSRP threshold, etc.

[0099] In some aspects, the auxiliary information may include L2 / L3 auxiliary information for UE-to-UE relaying. To assist the UE in performing relay reselection, the relay selection auxiliary information may be organized on a per-UE basis. For each UE, the relay selection auxiliary information may include the identifier of the connected destination UE. The relay selection auxiliary information may include, for example, the cell identifier of the cell associated with the relay UE, such as the PCI and the frequency carrying the PCI, CGI, TAI, etc. In some aspects, the relay selection auxiliary information may include the cell load information of the cell associated with the relay UE. The relay selection auxiliary information may include the load information of each cell, which the UE may use to preferentially connect via the sidelink to a cell with a lighter load relative to connecting via the sidelink to a cell with a heavier load. In some aspects, the relay selection auxiliary information may include the quality of service (QoS) information of the cell. The QoS information may include, for example, the minimum QoS supported by the relay Uu link (e.g., the link between the relay UE and the network entity) and / or the minimum QoS supported by the relay PC5 link (e.g., the link between the remote UE and the relay UE). In some aspects, the relay selection auxiliary information may include neighbor relay information, such as a list of relay UEs associated with the cell and the corresponding frequencies for measurement, and the connection status of the relay UE. The relay selection auxiliary information may include the public land mobile network information associated with the cell. In some aspects, the relay selection auxiliary information may include the relay selection and reselection parameters of each cell. The relay selection and reselection parameters may include, for example, the minimum reference signal received power (RSRP) for the cell to become a candidate cell, the minimum hysteresis value, the sidelink RSRP threshold, etc.

[0100] Generally, to select or reselect a relay UE, the remote UE may identify a suitable relay UE from the available relay UE domain. A suitable relay UE may be, for example, a UE that has the highest link quality on the sidelink connection between the remote UE and the relay UE and meets various higher-layer criteria that can be predefined a priori. Generally, the available relay UE domain may include relays associated with the same cell as the remote UE, as the context may remain the same for these relay UEs.

[0101] In some aspects, when the remote UE is within the coverage of the network entity with which the remote UE communicates via the relay UE, the radio resource management (RRM) procedures for the serving network entity and neighbor network entities may be relaxed. When relaxing the RRM procedures, a smaller number of measurement resources may be required, and the UE may perform measurements less frequently (e.g., using a larger minimum periodicity). In some aspects, different relaxed RRM parameters may be used for the serving network entity and the neighboring network entity.

[0102] In some aspects, the remote UE may be in a connected (e.g., RRC - connected) mode. In this case, radio link monitoring (RLM) parameters regarding the serving network entity may be relaxed. Similar to the relaxed RRM parameters discussed above, the relaxed RLM parameters may include using a smaller number of measurement resources and / or less frequent measurements.

[0103] In some aspects, the remote UE may communicate with a network entity via multi - path relay. To select a relay UE through which the remote UE communicates with the network entity, the remote UE may initially discover all relay UEs whose sidelink RSRP is higher than the minimum RSRP by a hysteresis value. Among these discovered relay UEs, the remote UE may select the relay node with the highest sidelink RSRP as the relay UE. The remote UE may also establish unicast sidelink RRC connections with other discovered relay UEs, and these discovered relay UEs may be considered "suitable" relay UEs. The sidelink connection with the selected relay UE may be activated by transmitting an indication from the remote UE in a sidelink radio resource control (RRC) or media access control (MAC) control element (CE) (MAC - CE). The selected relay UE may store the IP address and port number for relaying information to the remote UE upon receiving this indication, and may deactivate other sidelink connections.

[0104] In some aspects, the remote UE may perform sidelink RSRP measurements for certain sidelink connections to the relay UE. For example, when the sidelink RSRP of the connection between the remote UE and the selected relay UE exceeds the sidelink RSRP threshold, or when the minimum sidelink RSRP of the relay with a sidelink RRC connection exceeds the RSRP threshold, the remote UE may perform sidelink RSRP measurements. Otherwise, the remote UE may perform sidelink RSRP measurements for all discoverable relays and establish a new sidelink connection with a new relay UE.

[0105] When the connection between the selected relay UE and the remote UE becomes an inappropriate connection (e.g., the RSRP of the sidelink connection falls below the RSRP threshold), the remote UE may release the corresponding sidelink connection. A sidelink RRC connection may be established between the relay UE and one of the other suitable relay UEs. One of the other suitable relay UEs may be, for example, a relay UE with the best or highest RSRP of the sidelink connection, and the remote UE may connect to this remote UE via one of sidelink RRC signaling or sidelink MAC - CE signaling.

[0106] In some aspects, a remote UE may perform a path switch between a sidelink and a Uu link. For a remote UE connected to a relay and in a scenario where at least one suitable relay is associated with the same cell, the remote UE may perform relay selection but does not need to perform cell reselection. When no suitable relay UE is associated with the same cell, the remote UE may trigger a cell reselection procedure to establish a connection with a new cell (and accordingly, use the techniques described herein to establish a new sidelink connection with a new relay UE).

[0107] Figure 18 Illustrates a communication device 1800 that may include various components (e.g., corresponding to apparatus plus function components) configured to perform operations disclosed herein, such as the operations illustrated in Figure 15 The communication device 1800 includes a processing system 1802 coupled to a transceiver 1808. The transceiver 1808 is configured to transmit and receive signals for the communication device 1810 (such as the various signals described herein) via an antenna 1800. The processing system 1802 may be configured to perform processing functions for the communication device 1800, including processing signals received by and / or to be transmitted by the communication device 1800.

[0108] The processing system 1802 includes a processor 1804 coupled to a computer-readable medium / memory 1812 via a bus 1806. In some aspects, the computer-readable medium / memory 1812 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1804, cause the processor 1804 to perform the operations illustrated in Figure 15 or other operations for selecting and reselecting a relay UE in a sidelink L2 or L3 relay system based on discovery information. In some aspects, the computer-readable medium / memory 1812 stores code 1814 for receiving relay selection assistance information from a network entity, the relay selection assistance information identifying a plurality of relay UEs available for selection by the UE; code 1816 for selecting a first relay UE from the plurality of relay UEs based at least in part on the relay selection assistance information; and code 1818 for connecting to the selected first relay UE via a sidelink. In some aspects, the processor 1804 has circuitry configured to implement the code stored in the computer-readable medium / memory 1812. The processor 1804 includes circuitry 1820 for receiving relay selection assistance information from a network entity, the relay selection assistance information identifying a plurality of relay UEs available for selection by the UE; circuitry 1822 for selecting a first relay UE from the plurality of relay UEs based at least in part on the relay selection assistance information; and circuitry 1824 for connecting to the selected first relay UE via a sidelink.

[0109] Figure 19 A communication device 1900 is described that may include various components (e.g., corresponding to apparatus-plus-function components) configured to perform operations of the techniques disclosed herein, such as the operations illustrated in Figure 16 . The communication device 1900 includes a processing system 1902 coupled to a transceiver 1908. The transceiver 1908 is configured to transmit and receive signals for the communication device 1900 (such as the various signals described herein) via an antenna 1910. The processing system 1902 may be configured to perform processing functions for the communication device 1900, including processing signals received by and / or to be transmitted by the communication device 1900.

[0110] The processing system 1902 includes a processor 1904 coupled to a computer-readable medium / memory 1912 via a bus 1906. In some aspects, the computer-readable medium / memory 1912 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1904, cause the processor 1904 to perform the operations illustrated in Figure 16 or other operations for fast selection and reselection by a remote UE based on discovery information. In some aspects, the computer-readable medium / memory 1912 stores code 1914 for establishing a unicast connection with a remote UE via a sidelink; code 1916 for receiving, via the unicast connection, an indication from the remote UE to activate the unicast connection with the remote UE; and code 1918 for communicating with the remote UE via the unicast connection based on receiving the indication. In some aspects, the processor 1904 has circuitry configured to implement the code stored in the computer-readable medium / memory 1912. The processor 1904 includes circuitry 1920 for establishing a unicast connection with a remote UE via a sidelink; circuitry 1922 for receiving, via the unicast connection, an indication from the remote UE to activate the unicast connection with the remote UE; and circuitry 1924 for communicating with the remote UE via the unicast connection based on receiving the indication.

[0111] Figure 20 A communication device 2000 is described that may include various components (e.g., corresponding to apparatus-plus-function components) configured to perform operations of the techniques disclosed herein, such as the operations illustrated in Figure 17 . The communication device 2000 includes a processing system 2002 coupled to a transceiver 2008. The transceiver 2008 is configured to transmit and receive signals for the communication device 2000 (such as the various signals described herein) via an antenna 2010. The processing system 2002 may be configured to perform processing functions for the communication device 2000, including processing signals received by and / or to be transmitted by the communication device 2000.

[0112] The processing system 2002 includes a processor 2004 coupled to a computer-readable medium / memory 2012 via a bus 2006. In some aspects, the computer-readable medium / memory 2012 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 2004, cause the processor 2004 to perform Figure 17 the operations illustrated in or other operations for configuring a remote UE to select and reselect a relay UE based on discovery information. In some aspects, the computer-readable medium / memory 2012 stores code 2014 for transmitting relay selection assistance information to a remote user equipment (UE), the relay selection assistance information identifying a plurality of relay UEs available for selection by the remote UE; and code 2016 for communicating with the remote UE via one of the plurality of relay UEs. In some aspects, the processor 2004 has circuitry configured to implement the code stored in the computer-readable medium / memory 2012. The processor 2004 includes circuitry 2018 for transmitting relay selection assistance information to a remote user equipment (UE), the relay selection assistance information identifying a plurality of relay UEs available for selection by the remote UE; and circuitry 2020 for communicating with the remote UE via one of the plurality of relay UEs.

[0113] The methods disclosed herein include one or more steps or acts for implementing the method. These method steps and / or acts may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of the steps or acts is specified, the order and / or use of the specific steps and / or acts may be altered without departing from the scope of the claims.

[0114] As used herein, the phrase reciting "at least one of" a list of items refers to any combination of those items, including a single member. 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 having multiple like elements (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).

[0115] As used herein, the term "determine" encompasses a variety of actions. For example, "determine" may include computing, calculating, processing, deriving, researching, looking up (e.g., looking up in a table, database, or another data structure), ascertaining, and the like. Moreover, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Moreover, "determine" may include parsing, selecting, choosing, establishing, and the like.

[0116] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the 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, wherein the recitation of a single element is not intended to mean "one and only one" (unless specifically so stated) but "one or more." Unless specifically stated otherwise, the term "some" refers to one or more. Elements of the various aspects described throughout this disclosure that are presently known or later come to be known to those of ordinary skill in the art as structural and functional equivalents are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, whether or not such disclosure is expressly recited in the claims. No element of a claim should be construed under the provisions of 35 U.S.C. § 112(f), unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the element is recited using the phrase "step for."

[0117] The various operations of the methods described above can be performed by any suitable means capable of performing the corresponding functions. These means may include various hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs), or processors. In general, where there are operations illustrated in the figures, these operations may have corresponding paired means-plus-function components. For example, Figure 15 , Figure 16 and Figure 17 the various operations shown in can be performed by Figure 4 the various processors shown in, such as processors 466, 458, 464 of UE 120a and / or controller / processor 480.

[0118] The various illustrative logical blocks, modules, and circuits described in connection with the present disclosure can be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (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. The processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0119] If implemented in hardware, an example hardware configuration may include a processing system in a wireless node. The processing system can be implemented with a bus architecture. Depending on the specific application and overall design constraints of the processing system, the bus may include any number of interconnecting buses and bridges. The bus can link together various circuits including a processor, a machine-readable medium, and a bus interface. The bus interface can be used to connect, via the bus, a network adapter, etc. to the processing system. The network adapter can be used to implement the signal processing functions of the PHY layer. In the case of the user terminal 120 (see Figure 1 ), a user interface (e.g., keypad, display, mouse, joystick, etc.) can also be connected to the bus. The bus can also link various other circuits such as a timing source, peripherals, voltage regulators, power management circuits, and similar circuits, which are well known in the art and will not be described further herein. The processor can be implemented with one or more general-purpose and / or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry capable of executing software. Depending on the specific application and overall design constraints imposed on the overall system, those skilled in the art will recognize how best to implement the functionality described with respect to the processing system.

[0120] If implemented in software, the functions can be stored on or transmitted via a computer-readable medium as one or more instructions or code. Software should be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The computer-readable medium includes both computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. The processor can be responsible for managing the bus and general processing, including execution of software modules stored on a machine-readable storage medium. The computer-readable storage medium can be coupled to the processor such that the processor can read from and write to the storage medium. In an alternative, the storage medium can be integrated into the processor. As an example, the machine-readable medium can include a transmission line, a carrier modulated with data, and / or a computer-readable storage medium separate from the wireless node having instructions stored thereon, all of which can be accessed by the processor via the bus interface. Alternatively or additionally, the machine-readable medium or any part thereof can be integrated into the processor, such as may be the case with a cache and / or a general register file. As an example, examples of the machine-readable medium can include RAM (Random Access Memory), flash memory, ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable medium can be embodied in a computer program product.

[0121] A software module may include a single instruction or many instructions and may be distributed over several different code segments, distributed among different programs, and across multiple storage media. A computer-readable medium may include multiple software modules. These software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. These software modules may include a transmission module and a reception module. Each software module may reside in a single storage device or be distributed across multiple storage devices. As an example, when a triggering event occurs, a software module may be loaded from a hard drive into RAM. During execution of the software module, the processor may load some instructions into a cache to improve access speed. One or more cache lines may then be loaded into the general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when the processor executes instructions from the software module.

[0122] Likewise, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology such as infrared (IR), radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology such as infrared, radio, and microwave is included in the definition of the medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and disc, where disk often magnetically reproduces data, while disc optically reproduces data with a laser. Thus, in some aspects, a computer-readable medium may include a non-transitory computer-readable medium (e.g., a tangible medium). Additionally, for other aspects, a computer-readable medium may include a transitory computer-readable medium (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.

[0123] Accordingly, certain aspects may include a computer program product for performing the operations given herein. For example, such a computer program product may include a computer-readable medium having (and / or encoded thereon) instructions that can be executed by one or more processors to perform the operations described herein. For example, instructions for performing the operations described and illustrated in Figure 15 、 Figure 16 and Figure 17 。

[0124] In addition, it should be appreciated that modules and / or other suitable means for performing the methods and techniques described herein can be downloaded and / or otherwise obtained by a user terminal and / or a base station where applicable. For example, such devices can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage device (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or a floppy disk, etc.) such that once the storage device is coupled to or provided to the user terminal and / or the base station, the device can obtain the various methods. In addition, any other suitable technique for providing the methods and techniques described herein to the device can be utilized.

[0125] It will be understood that the claims are not limited to the exact configurations and components described above. Various changes, substitutions, and modifications can be made in the layout, operation, and details of the methods and apparatuses described above without departing from the scope of the claims.

Claims

1. A method for wireless communication by a user equipment (UE), comprising: receiving relay selection assistance information from a network entity, the relay selection assistance information identifying a plurality of relay UEs available for selection by the UE; selecting a first relay UE from the plurality of relay UEs at least partially based on the relay selection assistance information, wherein selecting the first relay UE from the plurality of relay UEs includes selecting a relay UE from a subset of relay UEs of the plurality of relay UEs, each relay UE in the subset of relay UEs being associated with the same cell as the UE and having a signal strength exceeding a threshold signal strength; and connecting to the selected first relay UE via a sidelink and establishing a unicast connection with each relay UE in the subset of relay UEs.

2. The method according to claim 1, wherein the relay selection assistance information is received in a discovery message.

3. The method according to claim 1, wherein the relay selection assistance information is received in a dedicated message received during a discovery procedure.

4. The method according to claim 1, wherein the relay selection assistance information is received in a system information block (SIB) broadcast by the network entity to the UE.

5. The method according to claim 1, wherein the relay selection assistance information includes information related to UE-to-network entity relaying, and wherein the relay selection assistance information is organized on a per-cell basis.

6. The method according to claim 5, wherein the relay selection assistance information for each cell includes one or more of the following: cell identifier information, cell load information, the minimum quality of service (QoS) metric supported by the link between the relay UE and the cell; neighbor relay information; the connection status of each neighbor relay; public land mobile network (PLMN) information for the cell; or relay selection and reselection parameters for the relay UE connected to the cell.

7. The method according to claim 1, wherein the relay selection assistance information includes information related to UE-to-UE relaying within the coverage of the network entity, and wherein the relay selection assistance information is organized on a per-UE basis.

8. The method according to claim 7, wherein the relay selection assistance information for each relay UE includes one or more of the following: information identifying the relay UE, cell identifier information of the cell associated with the relay UE, cell load information of the cell associated with the relay UE, the minimum quality of service (QoS) metric supported by the link between the relay UE and the cell; neighbor relay information; the connection status of each neighbor relay; public land mobile network (PLMN) information for the cell associated with the relay UE; or relay selection and reselection parameters for the relay UE.

9. The method according to claim 1, further comprising: Adjust radio resource management (RRM) parameters to perform measurements on the network entity and one or more neighboring network entities using a first set of adjusted RRM parameters for the network entity and a second set of adjusted RRM parameters for the one or more neighboring network entities, where the UE is in an idle, inactive, or connected mode at the network entity and the one or more neighboring network entities.

10. The method according to claim 1, further comprising: Adjusting radio link monitoring (RLM) parameters for performing measurements on a network entity in which the UE is in a connected mode.

11. The method according to claim 1, further comprising: Determining that the measured signal strength of a relay UE in the subset of relay UEs has dropped below the threshold signal strength; Sending a sidelink media access control (MAC) control element (CE) (MAC-CE) based at least on the determination to activate the relay UE in the subset of relay UEs; and Terminating the unicast connection for the relay UE in the subset of relay UEs.

12. The method according to claim 1, further comprising: Measuring the signal strength of the connection to the selected first relay UE; and Based on determining that the measured signal strength of the connection to the selected first relay UE exceeds the threshold signal strength, only measuring the signal strength for the subset of relay UEs.

13. The method according to claim 1, further comprising: Measuring the signal strength of the connection to the relay UE with the lowest signal strength in the subset of relay UEs; and Based on determining that the measured signal strength of the connection to the relay UE with the lowest signal strength in the subset of relay UEs exceeds the threshold signal strength, only measuring the signal strength for the subset of relay UEs.

14. The method according to claim 1, further comprising: Measuring the signal strength of at least one of the connection to the selected first relay UE or the connection to the relay UE with the lowest signal strength in the subset of relay UEs; and Based on determining that the measured signal strength of at least one of the connection to the selected first relay UE or the connection to the relay UE with the lowest signal strength in the subset of relay UEs is less than the threshold signal strength, measuring the signal strength for the plurality of relay UEs.

15. The method according to claim 1, further comprising: Determining that the signal strength of the connection to the selected first relay UE has dropped below the threshold signal strength; and Based on the determination: Releasing the connection to the selected first relay UE; and Activating a connection to a second relay UE in the subset of relay UEs via a sidelink media access control (MAC) control element (CE) (MAC-CE), where the second relay UE includes the UE with the highest connection signal strength in the subset of relay UEs.

16. The method according to claim 1, further comprising: Determine that the signal strength of the connection with the selected first relay UE has dropped below the threshold signal strength and that none of the relay UEs in the subset of relay UEs are suitable for reselection; and Based on the determination: Release the connection with the selected first relay UE; and Trigger a cell reselection procedure.

17. An apparatus for wireless communication at a user equipment UE, comprising means for performing any one of claims 1-16.

18. A method for wireless communication by a user equipment UE, comprising: Establish a unicast connection with a remote UE via a sidelink, wherein the UE and the remote UE are associated with the same cell and have a signal strength exceeding a threshold signal strength; Receive, via the unicast connection, an indication to activate the unicast connection with the remote UE from the remote UE; and Based on receiving the indication, communicate with the remote UE via the unicast connection.

19. An apparatus for wireless communication at a user equipment UE, comprising: Means for establishing a unicast connection with a remote UE via a sidelink, wherein the UE and the remote UE are associated with the same cell and have a signal strength exceeding a threshold signal strength; Means for receiving, via the unicast connection, an indication to activate the unicast connection with the remote UE from the remote UE; and Means for communicating with the remote UE via the unicast connection based on receiving the indication.

20. A method for wireless communication by a network entity, comprising: Transmit relay selection assistance information to a remote user equipment UE, the relay selection assistance information identifying a plurality of relay UEs available for selection by the remote UE; and Communicate with the remote UE via a first relay UE among the plurality of relay UEs, wherein the first relay UE is from a subset of relay UEs of the plurality of relay UEs, and each relay UE in the subset of relay UEs and the remote UE are associated with the same cell and have a signal strength exceeding a threshold signal strength.

21. The method according to claim 20, wherein the relay selection assistance information is transmitted to the remote UE in a discovery message.

22. The method according to claim 20, wherein the relay selection assistance information is transmitted to the UE in a dedicated message transmitted during a discovery procedure.

23. An apparatus for wireless communication at a network entity, comprising means for performing any one of claims 20-22.

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