WO2024093350A1

WO2024093350A1 - Multiple indirect paths in user equipment to network relay

Info

Publication number: WO2024093350A1
Application number: PCT/CN2023/106609
Authority: WO
Inventors: Lianhai WU; Ran YUE; Min Xu
Original assignee: Lenovo (Beijing) Limited
Priority date: 2023-07-10
Filing date: 2023-07-10
Publication date: 2024-05-10

Abstract

Various aspects of the present disclosure relate to multiple indirect paths in user equipment to network relay. In an aspect, a first user equipment comprises a processor and a transceiver coupled to the processor. The processor is configured to: receive via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS); and manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay. This way, communication connection can be maintained reliably with appropriate active indirect path.

Description

MULTIPLE INDIRECT PATHS IN USER EQUIPMENT TO NETWORK RELAY

TECHNICAL FIELD

The present disclosure relates to wireless communications, and more specifically to multiple indirect paths in user equipment to network relay.

BACKGROUND

A wireless communications system may include one or multiple network communication devices, such as base stations, which may be otherwise known as an eNodeB (eNB) , a next-generation NodeB (gNB) , or other suitable terminology. Each network communication devices, such as a base station may support wireless communications for one or multiple user communication devices, which may be otherwise known as user equipment (UE) , or other suitable terminology. The wireless communications system may support wireless communications with one or multiple user communication devices by utilizing resources of the wireless communication system (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers) . Additionally, the wireless communications system may support wireless communications across various radio access technologies including third generation (3G) radio access technology, fourth generation (4G) radio access technology, fifth generation (5G) radio access technology, among other suitable radio access technologies beyond 5G (e.g., sixth generation (6G) ) .

Sidelink communication supports user equipment (UE) to UE direct communication. Sidelink communication includes new radio (NR) sidelink communication, vehicle-to-everything (V2X) sidelink communication, and other sidelink communication modes. It is needed to manage path in sidelink communication, to maintain the stability of the connection in communication, and to deal with failures.

SUMMARY

The present disclosure relates to methods, apparatuses, and systems that support multiple indirect paths in user equipment to network relay.

In a first aspect of the solution a first user equipment (UE) receives via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) ; manages via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

In some implementations of the method and apparatuses described herein, managing the first indirect path comprises: receiving, via the transceiver and from the BS, an indication for activating the first indirect path via a medium access control (MAC) control element (CE) through a direct path between the first UE and the BS.

In some implementations of the method and apparatuses described herein, the indication is a first indication, and the processor is further configured to: based on receiving the first indication via the MAC CE, transmit, via the transceiver to the second UE, a second indication that the first indirect path is activated.

In some implementations of the method and apparatuses described herein, managing the first indirect path comprises: receiving, via the transceiver and from the second UE, an indication for activating the first indirect path via RRC message.

In some implementations of the method and apparatuses described herein, the indication comprises one of the following: an identifier (ID) of the second UE, a path index of the first indirect path, or an index of the first indirect path among the plurality of indirect paths.

In some implementations of the method and apparatuses described herein, the first user equipment further determines whether a condition for a change of an activated indirect path is met; based on determining that the condition is met, activates a second indirect path among the plurality indirect paths; and deactivate the first indirect path.

In some implementations of the method and apparatuses described herein, the condition comprises one of the following: a first link quality of a PC5 link of the first indirect path is less than a first quality threshold and a second link quality of a PC5 link of the second indirect path is greater than a second quality threshold; a third link quality of the PC5 link of the second indirect path becomes offset better than a fourth link quality of the PC5 link of the first indirect path; or the fifth link quality of the PC5 link of the first indirect path is less than a third quality threshold.

In some implementations of the method and apparatuses described herein, the first user equipment further determines whether a condition for activating an indirect path among the plurality indirect paths other than the first indirect path; and based on determining that the condition is met, activates a second indirect path among the plurality indirect paths.

In some implementations of the method and apparatuses described herein, the first user equipment further transmits, via the transceiver and to the BS, an indication that the first indirect path fails and the second indirect path is activated.

In some implementations of the method and apparatuses described herein, the condition comprises one of the following: a radio link failure (RLF) in a sidelink link of the first indirect path between the first UE and the second UE is detected; or a failure notification message or a release message is received from the second UE in the first indirect path.

In some implementations of the method and apparatuses described herein, one or more indirect paths among the plurality indirect paths other than the first indirect path are deactivated.

In some implementations of the method and apparatuses described herein, for the second indirect path among the one or more indirect paths which are deactivated: both of the first UE and a third UE acting as a relay in the second indirect path maintain a sidelink radio resource control (RRC) connection between the first UE and the third UE; one of the first UE and the third UE monitors the sidelink RRC connection wherein the other one is allowed to stop monitoring the sidelink RRC connection; the third UE avoids transmitting a failure notification message or a release message due to a handover or a RLF of the third UE; or in the case that the first UE receives the failure notification message or the release message from the third UE, the first UE avoids triggering a failure report.

In some implementations of the method and apparatuses described herein, a direct path is established and activated between the first UE and the BS; and the plurality of indirect paths including the first indirect path are activated.

In some implementations of the method and apparatuses described herein, the first user equipment further based on detecting an RLF in the direct path, transmits, via the transceiver and to the BS, a failure message for the direct path via a first indirect path among the plurality of indirect paths, wherein the first indirect path is configured with a signaling radio bearer (SRB) or a split SRB.

In some implementations of the method and apparatuses described herein, the first indirect path is one of multiple indirect paths configured with a SRB or a split SRB, and the first indirect path is selected from the multiple indirect paths based on one of the following: a configuration from the BS; a UE implementation; or channel qualities of the multiple indirect paths.

In some implementations of the method and apparatuses described herein, the failure message for the direct path is a first failure message, and the processor is further configured to: suspend the first indirect path based on detecting a RLF of the PC5 link in the first indirect path or receiving a failure notification message or a release message from the second UE in the first indirect path, prior to receiving, from the BS, a response to the first failure message; and transmit, via the transceiver and to the BS, a second failure message for the first indirect path via a second indirect path among the multiple indirect paths configured with a SRB or a split SRB.

In some implementations of the method and apparatuses described herein, the first user equipment further based on determining that the direct path and the multiple indirect paths are configured with a SRB or a split SRB fail, initiates a reestablishment procedure with the BS.

In some implementations of the method and apparatuses described herein, the first user equipment further based on determining that an amount of buffered data at the first UE is greater than an amount threshold, activates a second indirect path among the plurality indirect paths; and maintain the first indirect path to be activated.

In some implementations of the method and apparatuses described herein, the first user equipment further transmits, via the transceiver and to the BS, the buffered data via one of the following: a direct path, the first indirect path, and the second indirect path; or the first indirect path and the second indirect path.

In a second aspect, the base station transmits via the transceiver, a configuration for a plurality of indirect paths between a first user equipment (UE) and the BS; manages via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

In some implementations of the method and apparatuses described herein, managing the first indirect path comprises: transmitting, via the transceiver and to the first UE, an indication for activating the first indirect path via a medium access control (MAC) control element (CE) through a direct path between the first UE and the BS.

In some implementations of the method and apparatuses described herein, managing the first indirect path comprises: transmitting, via the transceiver and to the second UE, an indication for activating the first indirect path via RRC message.

In some implementations of the method and apparatuses described herein, the base station further transmits, via the transceiver and to the first UE, a condition for triggering a change of an activated indirect path.

In some implementations of the method and apparatuses described herein, the condition comprises one of the following: a first link quality of a PC5 link of the first indirect path is less than a first quality threshold and a second link quality of a PC5 link of a second indirect path among the plurality indirect paths is greater than a second quality threshold; a third link quality of the PC5 link of the second indirect path becomes offset better than a fourth link quality of the PC5 link of the first indirect path; or the fifth link quality of the PC5 link of the first indirect path is less than a third quality threshold.

In some implementations of the method and apparatuses described herein, the base station further transmits, via the transceiver and to the first UE, a condition for activating an indirect path among the plurality indirect paths other than the first indirect path.

In some implementations of the method and apparatuses described herein, the base station further receives, via the transceiver and from the first UE, an indication that the first indirect path fails and a second indirect path among the plurality indirect paths is activated.

In some implementations of the method and apparatuses described herein, the base station further in the case of an RLF in the direct path, receives, via the transceiver and from the first UE, a failure message for the direct path via a second indirect path among the plurality of indirect paths, wherein the second indirect path is configured with a signaling radio bearer (SRB) or a split SRB.

In some implementations of the method and apparatuses described herein, the second indirect path is one of multiple indirect paths configured with a SRB or a split SRB, and the second indirect path is selected from the multiple indirect paths based on one of the following: a configuration from the BS; a UE implementation; or channel qualities of the multiple indirect paths.

In some implementations of the method and apparatuses described herein, the failure message for the direct path is a first failure message, and the processor is further configured to: in the case that a RLF of the PC5 link in the second indirect path is detected or a failure notification message or a release message is transmitted in the second indirect path prior to transmitting, to the first UE, a response to the first failure message, receive, via the transceiver and from the first UE, a second failure message for the second indirect path via a third indirect path among the multiple indirect paths configured with a SRB or a split SRB.

In some implementations of the method and apparatuses described herein, the base station further transmits, via the transceiver and to the first UE, an amount threshold for comparing with an amount of buffered data at the first UE to determine whether to activate a second indirect path among the plurality indirect paths in addition to the first indirect path which is maintained to be activated.

In some implementations of the method and apparatuses described herein, the base station further receives, via the transceiver and from the first UE, the buffered data via one of the following: a direct path, the first indirect path, and the second indirect path; or the first indirect path and the second indirect path.

In a third aspect, there is provided a processor for wireless communication. The processor comprises: at least one memory; and a controller coupled with the at least one memory and configured to cause the controller to: receive via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) ; manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

In a fourth aspect, there is provided a processor for wireless communication. The processor comprises: at least one memory; and a controller coupled with the at least one memory and configured to cause the controller to: transmit via the transceiver, a configuration for a plurality of indirect paths between a first user equipment (UE) and the BS; manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

In a fifth aspect, there is provided a method performed by a user equipment (UE) , the method comprising: receiving via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) ; managing via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

In a sixth aspect, there is provided a method performed by a base station (BS) , the method comprising: transmitting via the transceiver, a configuration for a plurality of indirect paths between a first user equipment (UE) and the BS; managing via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

In a seventh aspect, there is provided a non-transitory computer readable medium having program instructions stored thereon. When the program instructions are executed by an apparatus, cause the apparatus to perform the method of the fifth aspect or the sixth aspect.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an example of a wireless communications system that supports multiple indirect paths in accordance with aspects of the present disclosure.

FIG. 1B illustrates an example of a wireless communications system that supports multiple indirect paths in accordance with aspects of the present disclosure.

FIG. 1C illustrates another example of a wireless communications system that supports multiple indirect paths in accordance with aspects of the present disclosure.

FIG. 2 illustrates an access network architecture that supports PC5 link associated with aspects of the present disclosure.

FIG. 3 illustrates a process flow that supports RRC reconfiguration for sidelink associated with aspects of the present disclosure.

FIG. 4 illustrates a network architecture with relay associated with aspects of the present disclosure.

FIG. 5 illustrates a process flow for relay path addition associated with aspects of the present disclosure.

FIG. 6 illustrates a process flow for communication with sidelink in accordance with aspects of the present disclosure.

FIGS. 7 through 8 illustrate examples of devices that support multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure.

FIGS. 9 through 10 illustrate examples of processors that support multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure.

FIGS. 11 through 14 illustrate flowcharts of methods that support multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar elements.

DETAILED DESCRIPTION

Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

References in the present disclosure to “one embodiment” , “an embodiment” , “an example embodiment” , and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as the fifth generation new radio (5G NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the fourth generation (4G) , 4.5G, the future fifth generation (5G) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term “network function” (NF) refers to a function in 5G core network, including at least one of Network Slice Selection Function (NSSF) , Network Exposure Function (NEF) , Network Repository Function (NRF) , Policy Control Function (PCF) , Unified Data Management (UDM) , Unified Data Repository (UDR) , Application Function (AF) , Network Data Analytics Function (NWDAF) , trusted non-3GPP gateway function (TNGF) , Authentication Server Function (AUSF) , Access and Mobility Management Function (AMF) , Session Management Function (SMF) , and User Plane Function (UPF) .

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (for example, remote surgery) , an industrial device and applications (for example, a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. In the following description, the terms “terminal device” , “communication device” , “terminal” may be used interchangeably.

Sidelink communication supports user equipment (UE) to UE direct communication. Sidelink communication includes new radio (NR) sidelink communication, vehicle-to- everything (V2X) sidelink communication, and other sidelink communication modes. It is needed to manage path in sidelink communication, to maintain the stability of the connection in communication, and to deal with failures.

In view of the above, embodiments of the present disclosure provide a solution for multiple indirect paths in the relay between the user equipment and the base network. In an aspect of the solution, a first user equipment (UE) receives via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) ; activates via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay. This way, communication connection can be maintained reliably with appropriate active indirect path.

Aspects of the present disclosure are described in the context of a wireless communications system.

FIG. 1A illustrates an example of a wireless communications system 100 that supports multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure. The wireless communications system 100 may include one or more network entities 102 (also referred to as network equipment (NE) ) , one or more UEs 104, a core network 106, and a packet data network 108. The wireless communications system 100 may support various radio access technologies. In some implementations, the wireless communications system 100 may be a 4G network, such as an LTE network or an LTE-Advanced (LTE-A) network. In some other implementations, the wireless communications system 100 may be a 5G network, such as an NR network. In other implementations, the wireless communications system 100 may be a combination of a 4G network and a 5G network, or other suitable radio access technology including Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20. The wireless communications system 100 may support radio access technologies beyond 5G. Additionally, the wireless communications system 100 may support technologies, such as time division multiple access (TDMA) , frequency division multiple access (FDMA) , or code division multiple access (CDMA) , etc.

The one or more network entities 102 may be dispersed throughout a geographic region to form the wireless communications system 100. One or more of the network entities 102 described herein may be or include or may be referred to as a network node, a base station, a network element, a radio access network (RAN) , a base transceiver station, an access point, a NodeB, an eNodeB (eNB) , a next-generation NodeB (gNB) , or other suitable terminology. A network entity 102 and a UE 104 may communicate via a communication link 110, which may be a wireless or wired connection. For example, a network entity 102 and a UE 104 may perform wireless communication (e.g., receive signaling, transmit signaling) over a Uu interface.

A network entity 102 may provide a geographic coverage area 112 for which the network entity 102 may support services (e.g., voice, video, packet data, messaging, broadcast, etc. ) for one or more UEs 104 within the geographic coverage area 112. For example, a network entity 102 and a UE 104 may support wireless communication of signals related to services (e.g., voice, video, packet data, messaging, broadcast, etc. ) according to one or multiple radio access technologies. In some implementations, a network entity 102 may be moveable, for example, a satellite associated with a non-terrestrial network. In some implementations, different geographic coverage areas 112 associated with the same or different radio access technologies may overlap, but the different geographic coverage areas 112 may be associated with different network entities 102. Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The one or more UEs 104 may be dispersed throughout a geographic region of the wireless communications system 100. A UE 104 may include or may be referred to as a mobile device, a wireless device, a remote device, a remote unit, a handheld device, or a subscriber device, or some other suitable terminology. In some implementations, the UE 104 may be referred to as a unit, a station, a terminal, or a client, among other examples. Additionally, or alternatively, the UE 104 may be referred to as an Internet-of-Things (IoT) device, an Internet-of-Everything (IoE) device, or machine-type communication (MTC) device, among other examples. In some implementations, a UE 104 may be stationary in the wireless communications system 100. In some other implementations, a UE 104 may be mobile in the wireless communications system 100.

The one or more UEs 104 may be devices in different forms or having different capabilities. Some examples of UEs 104 are illustrated in FIG. 1. A UE 104 may be capable of communicating with various types of devices, such as the network entities 102, other UEs 104, or network equipment (e.g., the core network 106, the packet data network 108, a relay device, an integrated access and backhaul (IAB) node, or another network equipment) , as shown in FIG. 1. Additionally, or alternatively, a UE 104 may support communication with other network entities 102 or UEs 104, which may act as relays in the wireless communications system 100.

A UE 104 may also be able to support wireless communication directly with other UEs 104 over a communication link 114. For example, a UE 104 may support wireless communication directly with another UE 104 over a device-to-device (D2D) communication link. In some implementations, such as vehicle-to-vehicle (V2V) deployments, vehicle-to-everything (V2X) deployments, or cellular-V2X deployments, the communication link 114 may be referred to as a sidelink. For example, a UE 104 may support wireless communication directly with another UE 104 over a PC5 interface.

A network entity 102 may support communications with the core network 106, or with another network entity 102, or both. For example, a network entity 102 may interface with the core network 106 through one or more backhaul links 116 (e.g., via an S1, N2, N2, or another network interface) . The network entities 102 may communicate with each other over the backhaul links 116 (e.g., via an X2, Xn, or another network interface) . In some implementations, the network entities 102 may communicate with each other directly (e.g., between the network entities 102) . In some other implementations, the network entities 102 may communicate with each other or indirectly (e.g., via the core network 106) . In some implementations, one or more network entities 102 may include subcomponents, such as an access network entity, which may be an example of an access node controller (ANC) . An ANC may communicate with the one or more UEs 104 through one or more other access network transmission entities, which may be referred to as a radio heads, smart radio heads, or transmission-reception points (TRPs) .

In some implementations, a network entity 102 may be configured in a disaggregated architecture, which may be configured to utilize a protocol stack physically or logically distributed among two or more network entities 102, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance) , or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN) ) . For example, a network entity 102 may include one or more of a central unit (CU) , a distributed unit (DU) , a radio unit (RU) , a RAN Intelligent Controller (RIC) (e.g., a Near-Real Time RIC (Near-RT RIC) , a Non-Real Time RIC (Non-RT RIC) ) , a Service Management and Orchestration (SMO) system, or any combination thereof.

An RU may also be referred to as a radio head, a smart radio head, a remote radio head (RRH) , a remote radio unit (RRU) , or a transmission reception point (TRP) . One or more components of the network entities 102 in a disaggregated RAN architecture may be co-located, or one or more components of the network entities 102 may be located in distributed locations (e.g., separate physical locations) . In some implementations, one or more network entities 102 of a disaggregated RAN architecture may be implemented as virtual units (e.g., a virtual CU (VCU) , a virtual DU (VDU) , a virtual RU (VRU) ) .

Split of functionality between a CU, a DU, and an RU may be flexible and may support different functionalities depending upon which functions (e.g., network layer functions, protocol layer functions, baseband functions, radio frequency functions, and any combinations thereof) are performed at a CU, a DU, or an RU. For example, a functional split of a protocol stack may be employed between a CU and a DU such that the CU may support one or more layers of the protocol stack and the DU may support one or more different layers of the protocol stack. In some implementations, the CU may host upper protocol layer (e.g., a layer 3 (L3) , a layer 2 (L2) ) functionality and signaling (e.g., Radio Resource Control (RRC) , service data adaption protocol (SDAP) , Packet Data Convergence Protocol (PDCP) ) . The CU may be connected to one or more DUs or RUs, and the one or more DUs or RUs may host lower protocol layers, such as a layer 1 (L1) (e.g., physical (PHY) layer) or an L2 (e.g., radio link control (RLC) layer, medium access control (MAC) layer) functionality and signaling, and may each be at least partially controlled by the CU 160.

Additionally, or alternatively, a functional split of the protocol stack may be employed between a DU and an RU such that the DU may support one or more layers of the protocol stack and the RU may support one or more different layers of the protocol stack. The DU may support one or multiple different cells (e.g., via one or more RUs) . In some implementations, a functional split between a CU and a DU, or between a DU and an RU may be within a protocol layer (e.g., some functions for a protocol layer may be performed by one of a CU, a DU, or an RU, while other functions of the protocol layer are performed by a different one of the CU, the DU, or the RU) .

A CU may be functionally split further into CU control plane (CU-CP) and CU user plane (CU-UP) functions. A CU may be connected to one or more DUs via a midhaul communication link (e.g., F1, F1-c, F1-u) , and a DU may be connected to one or more RUs via a fronthaul communication link (e.g., open fronthaul (FH) interface) . In some implementations, a midhaul communication link or a fronthaul communication link may be implemented in accordance with an interface (e.g., a channel) between layers of a protocol stack supported by respective network entities 102 that are in communication via such communication links.

The core network 106 may support user authentication, access authorization, tracking, connectivity, and other access, routing, or mobility functions. The core network 106 may be an evolved packet core (EPC) , or a 5G core (5GC) , which may include a control plane entity that manages access and mobility (e.g., a mobility management entity (MME) , an access and mobility management functions (AMF) ) and a user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW) , a Packet Data Network (PDN) gateway (P-GW) , or a user plane function (UPF) ) . In some implementations, the control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management (e.g., data bearers, signal bearers, etc. ) for the one or more UEs 104 served by the one or more network entities 102 associated with the core network 106.

The core network 106 may communicate with the packet data network 108 over one or more backhaul links 116 (e.g., via an S1, N2, N3 or another network interface) . The packet data network 108 may include an application server 118. In some implementations, one or more UEs 104 may communicate with the application server 118. A UE 104 may establish a session (e.g., a protocol data unit (PDU) session, or the like) with the core network 106 via a network entity 102. The core network 106 may route traffic (e.g., control information, data, and the like) between the UE 104 and the application server 118 using the established session (e.g., the established PDU session) . The PDU session may be an example of a logical connection between the UE 104 and the core network 106 (e.g., one or more network functions of the core network 106) .

In the wireless communications system 100, the network entities 102 and the UEs 104 may use resources of the wireless communications system 100 (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers) ) to perform various operations (e.g., wireless communications) . In some implementations, the network entities 102 and the UEs 104 may support different resource structures. For example, the network entities 102 and the UEs 104 may support different frame structures. In some implementations, such as in 4G, the network entities 102 and the UEs 104 may support a single frame structure. In some other implementations, such as in 5G and among other suitable radio access technologies, the network entities 102 and the UEs 104 may support various frame structures (i.e., multiple frame structures) . The network entities 102 and the UEs 104 may support various frame structures based on one or more numerologies.

A time interval of a resource (e.g., a communication resource) may be organized according to frames (also referred to as radio frames) . Each frame may have a duration, for example, a 10 millisecond (ms) duration. In some implementations, each frame may include multiple subframes. For example, each frame may include 10 subframes, and each subframe may have a duration, for example, a 1 ms duration. In some implementations, each frame may have the same duration. In some implementations, each subframe of a frame may have the same duration.

In the wireless communications system 100, an electromagnetic (EM) spectrum may be split, based on frequency or wavelength, into various classes, frequency bands, frequency channels, etc. By way of example, the wireless communications system 100 may support one or multiple operating frequency bands, such as frequency range designations FR1 (410 MHz –7.125 GHz) , FR2 (24.25 GHz –52.6 GHz) , FR3 (7.125 GHz –24.25 GHz) , FR4 (52.6 GHz –114.25 GHz) , FR4a or FR4-1 (52.6 GHz –71 GHz) , and FR5 (114.25 GHz –300 GHz) . In some implementations, the network entities 102 and the UEs 104 may perform wireless communications over one or more of the operating frequency bands. In some implementations, FR1 may be used by the network entities 102 and the UEs 104, among other equipment or devices for cellular communications traffic (e.g., control information, data) . In some implementations, FR2 may be used by the network entities 102 and the UEs 104, among other equipment or devices for short-range, high data rate capabilities.

FR1 may be associated with one or multiple numerologies (e.g., at least three numerologies) . For example, FR1 may be associated with a first numerology (e.g., μ=0) , which includes 15 kHz subcarrier spacing; a second numerology (e.g., μ=1) , which includes 30 kHz subcarrier spacing; and a third numerology (e.g., μ=2) , which includes 60 kHz subcarrier spacing. FR2 may be associated with one or multiple numerologies (e.g., at least 2 numerologies) . For example, FR2 may be associated with a third numerology (e.g., μ=2) , which includes 60 kHz subcarrier spacing; and a fourth numerology (e.g., μ=3) , which includes 120 kHz subcarrier spacing.

Sidelink (SL) communication supports UE-to-UE direct communication using two resource allocation modes, namely mode 1 and mode 2. In mode 1, the sidelink resource is scheduled by the base station. In mode 2, UE decides the SL transmission resources and timing in a resource pool based on the measurement result and sensing result in SL. Sidelink communication can include direct path or not include direct path.

FIG. 1B illustrates an example of a wireless communications system that supports multiple indirect paths in accordance with aspects of the present disclosure. In some embodiments, FIG. 1B illustrates sidelink communication with multiple paths including direct path and indirect paths. In Fig. 1B, the UE is in the coverage of the cell.

In the sidelink communication system 120, there are a base station (BS) 122, a first UE 125, a second UE 130, and a third UE 135. The first UE 125 is in the coverage 155 of the BS 122. There is a direct path 150 between the BS 122 and the first UE 125. The first UE 125 communicates with the second UE 130 in a sidelink connection 137, and communicates with the third UE 135 in a sidelink connection 139. The BS 122 can also communicate with the first UE 125 via indirect paths 140 and 145. In the indirect path 140, the second UE 130 acts as a relay between the BS 122 and the first UE 125. In the indirect path 145, the third UE 135 acts as a relay between the BS 122 and the first UE 125. The indirect path 140 can be a first indirect path, and the indirect path 145 can be a second indirect path between the base station 122 and the first UE 125. The skilled in the art can understand that there can be more than two indirect paths between the base station 122 and the first UE 125 via relays.

FIG. 1C illustrates another example of a wireless communications system that supports multiple indirect paths in accordance with aspects of the present disclosure. In some embodiments, FIG. 1C illustrates sidelink communication without direct path. In Fig. 1C, the UE is out of coverage of the cell.

In the sidelink communication system 160, The BS 122, the first UE 125, the second UE 130, and the third UE 135 can be the same with in the communication system 100 in FIG. 1A.The first UE 125 is not in the coverage 180 of the BS 122. There is no direct path between the BS 122 and the first UE 125. The first UE 125 communicates with the second UE 130 in a sidelink connection 162, and communicates with the third UE 135 in a sidelink connection 164. The BS 122 can communicate with the first UE 125 via indirect paths 165 and 170. In the indirect path 165, the second UE 130 acts as a relay between the BS 122 and the first UE 125. In the indirect path 170, the third UE 135 acts as a relay between the BS 122 and the first UE 125. The indirect path 165 can be a first indirect path, and the indirect path 170 can be a second indirect path between the base station 122 and the first UE 125. The skilled in the art can understand that there can be more than two indirect paths between the base station 122 and the first UE 125 via relays.

Sidelink communication includes NR sidelink communication and V2X sidelink communication. NR sidelink communication enables at least V2X communication between two or more nearby UEs, using NR technology but not traversing any network node. V2X sidelink communication enables communication between nearby UEs, using Evolved Universal Terrestrial Radio Access (E-UTRA) technology but not traversing any network node.

FIG. 2 illustrates an access network architecture that supports PC5 link associated with aspects of the present disclosure. Sidelink transmission and reception over the PC5 link are supported when the UE is inside NG-RAN coverage and when the UE is outside NG-RAN coverage.

In the access network architecture 200, a gNB 205 and a gNB 210 are in NG-RAN, the gNB 205 and the gNB 210 communicates in Xn link 230. A UE 215 and a UE 220 are inside the NG-RAN coverage of the gNB 205 and the gNB 210. The UE 215 communicates with the gNB 205 with a Uu link 235, and the UE 220 communicates with the gNB 210 with a Uu link 240. The UE 215 and the UE 220 communicates with a PC5 link 245 in sidelink connection. The UE 225 is outside the NG-RAN coverage of the gNB 205 and the gNB 210. The UE 225 communicates with the UE 215 with a PC5 link 250, and communicates with the UE 220 with a PC5 link 255. In some embodiments, the gNB 205 and the gNB 210 can be an implementation of the base station 122 in FIG. 1A or FIG. 1B. The UE 225, the UE 215, and the UE 220 can be an implementation of the first UE 125, the second UE 130, and the third UE 135 individually in FIG. 1A or FIG. 1B. The PC5 link 250 can be an implementation of the sidelink connection 137 in FIG. 1A, or the sidelink connection 162 in FIG. 1B. The PC5 link 255 can be an implementation of the sidelink connection 139 in FIG. 1A, or the sidelink connection 164 in FIG. 1B. The combination of the Uu link 235 and the PC5 link 250 can be an implementation of the indirect path 140 in FIG. 1A or the indirect path 165 in FIG. 1B. The combination of the Uu link 240 and the PC5 link 255 can be an implementation of the indirect path 145 in FIG. 1A or the indirect path 170 in FIG. 1B.

In some embodiments, support of V2X services via the PC5 link can be provided by NR sidelink communication or V2X sidelink communication. NR sidelink communication can support one of three types of transmission modes for a pair of a source layer-2 ID and a destination layer-2 ID: unicast transmission, groupcast transmission, and broadcast transmission.

FIG. 3 illustrates a process flow that supports RRC reconfiguration for sidelink associated with aspects of the present disclosure. In some embodiments, the purpose of the process flow in FIG. 3 is to modify a PC5-RRC connection, such as to establish or modify or release sidelink data radio bearers (DRBs) , to configure NR sidelink measurement and reporting, to configure sidelink channel state information (CSI) reference signal resources.

In some embodiments, UE1 310 can be an implementation of the first UE 125 in FIG. 1A or FIG. 1B, and UE2 320 an implementation of the second UE 130 or the third UE 135 in FIG. 1A or FIG. 1B.

In some embodiments, the UE1 310 may initiates the sidelink radio resource control (RRC) reconfiguration procedure and perform the operation in sub-clause 5.8.9.1.2 of 3GPP TS 38.331 specification on the corresponding PC5-RRC connection in following cases: the release of sidelink DRBs associated with the peer UE2 320, the establishment of sidelink DRBs associated with the peer UE2 320, the modification for the parameters included in SLRB-Config of sidelink DRBs associated with the peer UE2 320, as specified in sub-clause 5.8.9.1.5 in 3GPP TS 38.331 specification, the configuration of the peer UE2 320 to perform NR sidelink measurement and report, the configuration of the sidelink CSI reference signal resources. In the process flow 300, the UE1 310 sends (330) RRCReconfigurationSideLink message 325 to the UE2 320. The UE2 320 sends (340) RRCReconfigurationCompleteSideLink message 335 to the UE1 310.

FIG. 4 illustrates a network architecture with relay associated with aspects of the present disclosure. Specifically, FIG. 4 illustrates the network architecture that further explores coverage extension for sidelink based communication.

In some embodiments, for UE-to-network coverage extension, Uu coverage reachability is necessary for UEs to reach server in PDN network or counterpart UE out of proximity area. However, release-13 solution on UE-to-network relay is limited to EUTRA-based technology, and thus cannot be applied to NR-based system, for both NG-RAN and NR-based sidelink communication. For UE-to-UE coverage extension, currently proximity reachability is limited to single-hop sidelink link, either via EUTRA-based or NR-based sidelink technology. However, that is not sufficient in the scenario where there is no Uu coverage, considering the limited single-hop sidelink coverage. In this case, a UE 420 out of coverage 440 accesses a gNB 410 via relay a UE 430. There are RRC connection between the UE 420 and the gNB 410. The UE 420 has a RRC state, such as RRC_idle state, RRC_inactive and RRC_connected state. There is no Uu link or direct path between the UE 420 and the gNB 410, and there is only one sidelink for the UE 420, thus only one indirect path or relay path between the UE 420 and the gNB 410. It is not sufficient for communication for the UE 420.

FIG. 5 illustrates a process flow for relay path addition associated with aspects of the present disclosure. In the process flow 500, a serving gNB 510 can be an implementation of the base station 122 in FIG. 1A or FIG. 1B, a remote UE 513 can be an implementation of the first UE 125 in FIG. 1A or FIG. 1B, and a relay UE 515 can be an implementation of the third UE 135 in FIG. 1A or FIG. 1B. According to FIG. 1A or FIG. 1B, the process flow 500 can add the second indirect path 145 via the third UE 135 based on the first indirect path 140 in FIG. 1A, or can add the second indirect path 170 via the third UE 135 based on the first indirect path 165 in FIG. 1B.

The remote UE 513 sends (525) a measurement report 520 to the server gNB 510. At 530, the serving gNB 510 decides to establish multi-path, or decides to add the second indirect path based on the first indirect path. The serving gNB 510 sends (545) to the remote UE 513, a RRC reconfiguration message 540 for path adding. The PC5 connection establishment message 550 is transmitted (555) between the remote UE 513 and the relay UE 515. The serving gNB sends (565) an RRC reconfiguration message 560 for the remote UE 513. The remote UE 513 sends (575) an ReconfigurationComplete message 570 to the serving gNB 510. At this step, the RRC connection is established in the additional second indirect path between the remote UE 513 and the serving gNB 510 via the relay UE 515. The data transmission or reception 580 can be performed (585) in the additional second indirect path, or additional relay path.

The skilled in the art can understand that the process 500 can also be used for establishing the first indirect path, or adding the (N+1) th indirect path based on the Nth indirect path between the serving gNB 510 and the remote UE 513.

FIG. 6 illustrates a process flow for communication with sidelink in accordance with aspects of the present disclosure. In the process flow 600, the base station 122 sends (615) a configuration for a plurality of indirect paths 610 between the first UE 125 and the base station 122. The base station 122 or the first UE 125 manages (625) such as activates a first indirect path 620 among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE 125 and the BS 122 via the second UE 130 acting as a relay.

In the embodiments, there can be several cases. In case A, only one indirect path is allowed to be activated, to transmit or receive data if a plurality of candidate indirect paths are established between the base station 122 and the first UE 125. In case B, at least two activated indirect paths can be used in parallel between the base station 122 and the first UE 125. In case C, the first UE 125 can switch from one active indirect path to two active indirect paths.

In the embodiments, in case A, issue 1 is how to select one of multiple indirect paths, such as two indirect paths for data transmission and reception. In option 1, the base station 122 such as the gNB activates one of multiple indirect paths, such as the first indirect path 140 in FIG. 1A via media access control (MAC) control element (CE) . One indication is used to indicate the activated indirect path. The indication could be ID of the second UE 130, path index or the index of multiple indirect paths configured to the first UE 125. The MAC CE can be transmitted via the direct path 150. Once the first UE 125 receives the MAC CE, the first UE 125 needs to indicate it to the corresponding relay UE, or the second UE 130. This way, the indication for activating the first indirect path 140 can be transmitted in the direct path 150 reliably.

In some embodiments, for issue 1, in option 2, the BS 122 indicates to the relay UE, such as the second UE 130, which end-to-end link is activated or deactivated. In the embodiments, the activated or deactivated link can be the first indirect path 140 in FIG. 1A, or the first indirect path 165 in FIG. 1B. The corresponding remote UE ID, or the ID of the second UE 130 is included to indicate the firs indirect path. Then, the relay UE, such as the second UE 130 will indicate the activation indication to the remote UE such as the first UE 125 accordingly. This way, the base station 122 can indicate the activation or the deactivation flexibly.

In some embodiments, for issue 1, in option 3, one condition for activation change is configured from the BS 122 to the first UE 125, such as changing the active indirect path from the first indirect path 140 to the second indirect path 145 in FIG. 1A, or changing the active indirect path from the first indirect path 165 to the second indirect path 170 in FIG. 1B. The condition can be the link quality of the PC5 of first indirect path is less than a configured first quality threshold, and the link quality of the PC5 of a candidate indirect path such as the second path is greater than a configured second quality threshold.

Alternatively, the condition can also be the link quality of PC5 of a candidate indirect path such as the second indirect path becomes offset better than the PC5 of current indirect path such as the first indirect path. Alternatively, the condition can also be the link quality of the first indirect path is less than a third quality threshold. The link quality can be at least one of: channel busy ratio (CBR) , sidelink reference signal receive power (SL-RSRP) , sidelink discovery reference signal receive power (SD-RSRP) . The skilled in the art can understand that the link quality can be other parameters, and the threshold can be determined with measurement. This way, the active indirect path can be changed according to link quality or channel condition, thus keep the RRC connection reliably between the base station 122 and the first UE 125.

In some embodiments, in issue 1, in option 4, the first UE 125 autonomously activates another indirect path, such as changes the active indirect path from the first indirect path to the second indirect path when the following condition occurs. After completing change, the second UE 125 can report the failure and activated indirect path to the BS 122. The condition can be a PC5 failure in the current active indirect path such as the first indirect path, or reception of notification message or release message from the current indirect path. This way, the active indirect path can be changed according to link quality or channel condition, thus keep the RRC connection reliably between the base station 122 and the first UE 125.

In some embodiments, in case A, issue 2 is what is the state for the indirect path in which data is not allowed. None of the first UE 125 or the BS 122 will transmit the data via the second indirect path 145 in FIG. 1A or the second indirect path 170 in FIG. 1B. In the de-activated second indirect path, both the first UE 125 and the third UE 135 will continue maintaining PC5 RRC in sidelink. One of the first UE 125 and the third UE 135 keeps monitoring PC5 link, while the other one is allowed to stop monitoring the PC5 link. The relay UE such as the third UE 135 may not transmit notification message or release message due to handover or radio link failure (RLF) of third UE 135. If the remote UE such as the first UE 125 receives notification message or release message due to handover or RLF of the third UE 135 from the third UE 135, the first UE 10 may not trigger failure report. This way, signal can be saved for the inactive indirect path.

In some embodiments, in case B, issue 3 is which indirect path can be used for transmitting the failure information such as MCG failure information, when there is a failure in the direct path 150 between the BS 122 and the first UE 125 in FIG. 1A. If a timer such as T316 is configured for relay case in the first UE 125, the first UE 125 considers that reporting information for failure of the direct path 150 is supported. Otherwise, the first UE 125 performs re-establishment procedure. If only one indirect path such as the first indirect path 140 has signaling radio bearer (SRB) and RLF occurs on the direct path 150, master cell group (MCG) failure information procedure can be triggered. The MCG failure information can be transmitted via the indirect path configured with SRB or split SRB. In splitting SRB, SRB1 and SRB2 can be split into three links including the direct path 150, and the two indirect paths 140 and 145. MCG failure information procedure can be triggered if RLF occurs on the direct path 150.

For indirect path selection, option 1 is that the BS 122 configures which indirect path can be used to carry MCG failure information if both are available configured with SRB. In some embodiments, the BS 122 configures that the first indirect path 140 can be used to carry MCG failure information if both the indirect paths 140 and 145 are available configured with SRB. Option 2 is that the first UE 125 selects one indirect path such as the first indirect path 140 based on UE implementation or channel quality. This way, the MCG failure information of the direct path 150 can be reported to the BS 122 via indirect path, to keep the RRC connection reliable between the base station 122 and the first UE 125, and make reliable failure management.

In some embodiments, in case C, issue 4 is how to switch between only one activated indirect path and two activated indirect paths. If buffered data is greater than an amount threshold, two indirect paths can be used to transmit or receive data instead of one indirect path. The buffered data can be associated with both direct path and indirect paths. Or buffered data is only related to the indirect paths. This way, more indirect path can be used for transmitting or receiving the buffered data greater than the amount threshold, to prevent packet loss or congestion, thus improve the performance of communication between the BS 122 and the first UE 125.

In some embodiments, according to case A, options 1 and 2 of issue 1 and issue 2, the first UE 125 stays at RRC connected state. The first UE 125 is configured with more than one indirect path, such as indirect paths 140, 150 in FIG. 1A, or indirect paths 165, 170 in FIG. 1B. The first UE 125 accesses the base station 122 such as the serving gNB via one activated indirect path associated with a relay UE. The activated indirect path can be the first indirect path 140 in FIG. 1A, or the first indirect path 165 in FIG. 1B, via the second UE 130. The activated indirect path means the first UE 125 is allowed to transmit data to network, or receive data from network in this indirect path. It is optional that there is a direct path 150 in FIG. 1A for the first UE 125 wherein the direct path 150 refers to the Uu interface. If the first UE 125 is configured with more than one indirect path, the indirect path which is not activated is a candidate or deactivated indirect path, such as the second indirect path 145 in FIG. 1A, or the second indirect path 170 in FIG. 1B. The candidate indirect path is a backup indirect path in which the data towards network is not allowed.

In some embodiments, the definition of the candidate or deactivated indirect path is as follows: both remote UE (such as the first UE 125) and relay UE (such as the third UE 135) will continue maintaining PC5 RRC. One of the first UE 125 and the third UE 135 keeps monitoring the PC5 link, and the other one can stop monitoring. The relay UE such as the third UE 135 may not transmit the notification message or the release message due to handover or RLF of the relay UE. If the remote UE such as the first UE 125 receives the notification message or the release message due to handover or RLF of the relay UE from the relay UE, the remote UE may not trigger failure report. This way, signal can be saved for the inactive indirect path.

If the BS 122 such as the gNB wants to activate another indirect path such as the first indirect path, the BS 122 may transmit the indication to the first UE 125. In one option, the BS 122 can activate one of multiple indirect paths via MAC CE. One indication is used to indicate the activated first indirect path 140 in FIG. 1A. The indication could be relay UE ID or the ID of the second UE 130, path index or the index of multiple indirect paths configured to the first UE 125. The MAC CE should be transmitted via the direct path 150. Once the first UE 125 receives the MAC CE, the first UE 125 can indicate it to the corresponding relay UE such as the second UE 130. In the other option, the BS 122 indicates to the relay UE which end-to-end link is activated or deactivated. The corresponding remote UE ID is included to indicate the end-to-end link. Then, the relay UE will indicate the activation indication to the remote UE accordingly. For example, the BS 122 indicates to the second UE 130 that the first indirect path 140 is activated or deactivated. The corresponding ID of the first UE 125 is included to indicate the end-to-end link. Then, the second UE 130 will indicate the activation indication to the first UE 125 accordingly. This way, the base station can activate or de-activate indirect path flexibly.

In some embodiments, according to case A, options 3 of issue 1 and issue 2, the first UE 125 stays at RRC connected state. The first UE 125 accesses the BS 122 such as the serving gNB via one activated indirect path such as the first indirect path 140 in FIG. 1A or the first indirect path 165 in FIG. 1B associated with a relay UE such as the second UE 130, wherein the first UE 125 is configured with more than one indirect path. The activated indirect path means the first UE 125 is allowed to transmit data to the network or receive data from the network in this indirect path. It is optional that there is a direct path such as the direct path 150 in FIG. 1A for the first UE 125 wherein the direct path refers to the Uu interface. If the first UE 125 is configured with more than one indirect path, the indirect path which is not activated is a candidate indirect path such as the second indirect path 145 in FIG. 1A or the second indirect path 170 in FIG. 1B. The candidate indirect path is a backup indirect path in which the data towards network is not allowed.

The base station 122 indicates to the relay UE such as the second UE 130 which end-to-end link is activated or deactivated. The corresponding remote UE ID is included to indicate the end-to-end link. Then, the relay UE will indicate the activation indication to the first UE 125 accordingly. One condition for activation change is configured to the first UE 125. Alternatively, the condition can also be that the link quality of the PC5 of current indirect path is less than the configured first quality threshold, and the link quality of PC5 of a candidate indirect path is greater than the configured second quality threshold. Alternatively, the condition can be that the link quality of PC5 of a candidate indirect path becomes offset better than the link quality of PC5 of the current indirect path. Alternatively, the condition can also be that the link quality of the current indirect path is less than the third quality threshold. The link quality can be at least one of CBR, SL-RSRP, or SD-RSRP. The skilled in the art can understand that other parameters can also be used as the link quality. The first UE 125 evaluates the condition after the first UE 125 receives the configuration for the condition. Once the condition is met, the first UE 125 will activate the corresponding candidate indirect path. This way, the UE can change active indirect path flexibly, according to link quality or channel condition.

In some embodiments, according to case A, options 4 of issue 1 and issue 2, the first UE 125 stays at RRC connected state. The first UE 125 accesses base station 100 such as the serving gNB via one activated indirect path such as the first indirect path 140 in FIG. 1A or the first indirect path 165 in FIG. 1B associated with the relay UE such as the second UE 130, wherein the first UE 125 is configured with more than one indirect path. The activated indirect path means the first UE 125 is allowed to transmit data to the network or receive data from the network in this indirect path. It is optional that there is the direct path such as the direct path 150 in FIG. 1A for the first UE 125 wherein the direct path refers to the Uu interface. If the first UE 125 is configured with more than one indirect path, the indirect path which is not activated is a candidate indirect path, such as the second indirect path 145 in FIG. 1A or the second indirect path 170 in FIG. 1B.

The candidate indirect path is a backup indirect path in which the data towards network is not allowed. The base station 122 such as the gNB indicates to the relay UE such as the second UE 130 which end-to-end link is activated or deactivated. The corresponding remote UE ID such as the ID of the second UE 130 is included to indicate the end-to-end link. Then, the relay UE such as the second UE 130 will indicate the activation indication to the remote UE such as the first UE 125 accordingly. The first UE 125 autonomously activates another candidate indirect path when the following condition occurs. The condition can be PC5 RLF in the current active indirect path or reception of notification message or release message from the current indirect path. The first UE 125 can report the failure and candidate indirect path to be activated to the base station 122 such as the serving gNB. This way, the first UE 125 can change active indirect path flexibly.

In some embodiments, according to case B, issue 3, the first UE 125 stays at RRC connected state. The first UE 125 is configured with one or more than one indirect path. The first UE 125 accesses the base station 122 or the serving gNB via more than one activated indirect paths in which each indirect path is associated with a relay UE. For example, in FIG. 1A, there are two active indirect paths between the base station 122 and the first UE 125, the first indirect path 140 via the second UE 130 and the second indirect path 145 via the third UE 135. In FIG. 1B, there are two active indirect paths between the base station 122 and the first UE 125, the first indirect path 165 via the second UE 130 and the second indirect path 170 via the third UE 135.

The activated indirect path means the first UE 125 is allowed to transmit data to the network or receive data from the network in this indirect path. Optionally, there can be a direct path such as the direct path 150 in FIG. 1A for the first UE 125 wherein the direct path refers to the Uu interface. Optionally, all the configured indirect paths are activated. UE detects RLF on direct path or path switching of direct path fails. The first UE 125 reports failure message to the base station 122 such as the serving gNB via one available indirect path if SRB is configured. If the timer such as T316 is configured in the first UE 125 for relay case, the first UE 125 considers the MCG failure information for direct path failure is supported.

Otherwise, the first UE 125 performs re-establishment procedure directly. If only one indirect path has SRB and RLF occurs on the direct path 150, MCG failure information procedure can be triggered. The MCG failure information message can be transmitted via indirect path configured with SRB or split SRB. SRB1 and SRB2 can be split into three links including direct path and two indirect paths. MCG failure information procedure can be triggered if RLF occurs on the direct path 150. In order to choose the indirect path to carry the MCG failure information message, one option is that the base station 122 such as the serving gNB configures which indirect path can be used to carry the MCG failure information message if both are available configured with SRB.

For example, the base station 122 configures to the first UE 125 that the first indirect path 140 can be used to carry the MCG failure information message. The other option is that the first UE 125 selects one indirect path based on UE implementation or channel quality. The first UE 125 will receive the response after transmitting failure report for the direct path 150, such as the MCG failure information message. The response could be path switching command for direct path. The response is restricted to the link such as the first indirect path 140 transmitting the failure report for the direct path. Or the response can be transmitted in any indirect path.

In some embodiments, after the first UE 125 transmits the failure report such as the MCG failure information message to the base station 122 such as the serving gNB, the first UE 125 suspends the indirect path such as the first indirect path 140 due to slidelink RLF, reception of notification message or release messages before receiving response from the BS 122 such as the gNB. In this case, the first UE 125 continues running timer T316-like. The first UE 125 transmits failure report for the first indirect path 140 to the gNB via the second indirect path 145.

Failure report for the first indirect path 140 includes the relay UE ID such as ID of the second UE 130 which is used to indicate the failed indirect path. Then, the network such as the BS 122 will be aware of that both direct path and the first indirect path 140 are unavailable. If the second indirect path 145 is suspended due to slidelink RLF, reception of notification message or release message before receiving response from the gNB, the first UE 125 initiates re-establishment procedure. Namely, the first UE 125 initiates re-establishment procedure when all paths configured with SRB fail. This way, the BS 122 can manage the link failure in direct path or indirect path, and improve the communication performance.

In some embodiments, according to case C, issue 4, the first UE 125 stays at RRC connected state. The first UE 125 is configured with more than one indirect path. One indirect path such as the first indirect path 140 in FIG. 1A or the first indirect path 165 in FIG. 1B is activated. The activated indirect path means the first UE 125 is allowed to transmit data to the network or receive data from network in this indirect path. It is optional that there is a direct path such as the direct path 150 in FIG. 1A for the first UE 125 wherein the direct path refers to the Uu interface. If the first UE 125 is configured with more than one indirect path, the indirect path which is not activated such as the second indirect path 145 in FIG. 1A or the second indirect path 170 in FIG. 1B is a candidate or deactivated indirect path. The candidate indirect path is a backup indirect path in which the data towards network is not allowed.

A threshold such as an amount threshold for activating more indirect path is configured to the first UE 125. If buffered data is greater than the amount threshold, the second indirect path 145 or 170 with the state of deactivated can be activated. Namely, two indirect paths can be used to transmit or receive data. The buffered data could be associated with both direct path and indirect path. Or the buffered data is only related to indirect path. The split bearer is configured in the second indirect path 145 or 170. This way, more buffered data can be transmitted or received smoothly, to avoid packet loss or congestion, thus improve communication performance.

FIG. 7 illustrates an example of a device 700 that supports multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure. The device 700 may be an example of a first user equipment 125 as described herein. The device 700 may support wireless communication with one or more of the firs user equipment 125, the BS 122, or any combination thereof. The device 700 may include components for bi-directional communications including components for transmitting and receiving communications, such as a processor 702, a memory 704, a transceiver 706, and, optionally, an I/O controller 708. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses) .

The processor 702, the memory 704, the transceiver 706, or various combinations thereof or various components thereof may be examples of means for performing various aspects of the present disclosure as described herein. For example, the processor 702, the memory 704, the transceiver 706, or various combinations or components thereof may support a method for performing one or more of the operations described herein.

In some implementations, the processor 702, the memory 704, the transceiver 706, or various combinations or components thereof may be implemented in hardware (e.g., in communications management circuitry) . The hardware may include a processor, a digital signal processor (DSP) , an application-specific integrated circuit (ASIC) , a field-programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting a means for performing the functions described in the present disclosure. In some implementations, the processor 702 and the memory 704 coupled with the processor 702 may be configured to perform one or more of the functions described herein (e.g., executing, by the processor 702, instructions stored in the memory 704) .

For example, the processor 702 may support wireless communication at the device 700 in accordance with examples as disclosed herein. The processor 702 may be configured to operable to support a means for multiple indirect paths in user equipment to network relay.

The processor 702 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a micro-controller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some implementations, the processor 702 may be configured to operate a memory array using a memory controller. In some other implementations, a memory controller may be integrated into the processor 702. The processor 702 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 704) to cause the device 700 to perform various functions of the present disclosure.

The memory 704 may include random access memory (RAM) and read-only memory (ROM) . The memory 704 may store computer-readable, computer-executable code including instructions that, when executed by the processor 702 cause the device 700 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. In some implementations, the code may not be directly executable by the processor 702 but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some implementations, the memory 704 may include, among other things, a basic I/O system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The I/O controller 708 may manage input and output signals for the device 700. The I/O controller 708 may also manage peripherals not integrated into the device M02. In some implementations, the I/O controller 708 may represent a physical connection or port to an external peripheral. In some implementations, the I/O controller 708 may utilize an operating system such asor another known operating system. In some implementations, the I/O controller 708 may be implemented as part of a processor, such as the processor 706. In some implementations, a user may interact with the device 700 via the I/O controller 708 or via hardware components controlled by the I/O controller 708.

In some implementations, the device 700 may include a single antenna 710. However, in some other implementations, the device 700 may have more than one antenna 710 (i.e., multiple antennas) , including multiple antenna panels or antenna arrays, which may be capable of concurrently transmitting or receiving multiple wireless transmissions. The transceiver 706 may communicate bi-directionally, via the one or more antennas 710, wired, or wireless links as described herein. For example, the transceiver 706 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 706 may also include a modem to modulate the packets, to provide the modulated packets to one or more antennas 710 for transmission, and to demodulate packets received from the one or more antennas 710. The transceiver 706 may include one or more transmit chains, one or more receive chains, or a combination thereof.

A transmit chain may be configured to generate and transmit signals (e.g., control information, data, packets) . The transmit chain may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques such as amplitude modulation (AM) , frequency modulation (FM) , or digital modulation schemes like phase-shift keying (PSK) or quadrature amplitude modulation (QAM) . The transmit chain may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over the wireless medium. The transmit chain may also include one or more antennas 710 for transmitting the amplified signal into the air or wireless medium.

A receive chain may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, the receive chain may include one or more antennas 710 for receive the signal over the air or wireless medium. The receive chain may include at least one amplifier (e.g., a low-noise amplifier (LNA) ) configured to amplify the received signal. The receive chain may include at least one demodulator configured to demodulate the receive signal and obtain the transmitted data by reversing the modulation technique applied during transmission of the signal. The receive chain may include at least one decoder for decoding the processing the demodulated signal to receive the transmitted data.

FIG. 8 illustrates an example of a device 800 that supports multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure. The device 800 may be an example of a base station 122 as described herein. The device 800 may support wireless communication with one or more of the firs user equipment 125, the BS 122, or any combination thereof. The device 800 may include components for bi-directional communications including components for transmitting and receiving communications, such as a processor 802, a memory804, a transceiver 806, and, optionally, an I/O controller 808. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses) .

The processor 802, the memory 804, the transceiver 806, or various combinations thereof or various components thereof may be examples of means for performing various aspects of the present disclosure as described herein. For example, the processor 802, the memory 804, the transceiver 806, or various combinations or components thereof may support a method for performing one or more of the operations described herein.

In some implementations, the processor 802, the memory 804, the transceiver 806, or various combinations or components thereof may be implemented in hardware (e.g., in communications management circuitry) . The hardware may include a processor, a digital signal processor (DSP) , an application-specific integrated circuit (ASIC) , a field-programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting a means for performing the functions described in the present disclosure. In some implementations, the processor 802 and the memory 804 coupled with the processor 802 may be configured to perform one or more of the functions described herein (e.g., executing, by the processor 802, instructions stored in the memory 804) .

For example, the processor 802 may support wireless communication at the device 700 in accordance with examples as disclosed herein. The processor 802 may be configured to operable to support a means for multiple indirect paths in user equipment to network relay.

The processor 802 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a micro-controller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some implementations, the processor 802 may be configured to operate a memory array using a memory controller. In some other implementations, a memory controller may be integrated into the processor 802. The processor 802 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 804) to cause the device 800 to perform various functions of the present disclosure.

The memory 804 may include random access memory (RAM) and read-only memory (ROM) . The memory 804 may store computer-readable, computer-executable code including instructions that, when executed by the processor 802 cause the device 800 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. In some implementations, the code may not be directly executable by the processor 802 but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some implementations, the memory 804 may include, among other things, a basic I/O system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The I/O controller 808 may manage input and output signals for the device 800. The I/O controller 808 may also manage peripherals not integrated into the device M02. In some implementations, the I/O controller 808 may represent a physical connection or port to an external peripheral. In some implementations, the I/O controller 808 may utilize an operating system such asor another known operating system. In some implementations, the I/O controller 808 may be implemented as part of a processor, such as the processor 806. In some implementations, a user may interact with the device 800 via the I/O controller 808 or via hardware components controlled by the I/O controller 808.

In some implementations, the device 800 may include a single antenna 810. However, in some other implementations, the device 800 may have more than one antenna 810 (i.e., multiple antennas) , including multiple antenna panels or antenna arrays, which may be capable of concurrently transmitting or receiving multiple wireless transmissions. The transceiver 806 may communicate bi-directionally, via the one or more antennas 810, wired, or wireless links as described herein. For example, the transceiver 806 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 806 may also include a modem to modulate the packets, to provide the modulated packets to one or more antennas 810 for transmission, and to demodulate packets received from the one or more antennas 810. The transceiver 806 may include one or more transmit chains, one or more receive chains, or a combination thereof.

A transmit chain may be configured to generate and transmit signals (e.g., control information, data, packets) . The transmit chain may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques such as amplitude modulation (AM) , frequency modulation (FM) , or digital modulation schemes like phase-shift keying (PSK) or quadrature amplitude modulation (QAM) . The transmit chain may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over the wireless medium. The transmit chain may also include one or more antennas 810 for transmitting the amplified signal into the air or wireless medium.

A receive chain may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, the receive chain may include one or more antennas 810 for receive the signal over the air or wireless medium. The receive chain may include at least one amplifier (e.g., a low-noise amplifier (LNA) ) configured to amplify the received signal. The receive chain may include at least one demodulator configured to demodulate the receive signal and obtain the transmitted data by reversing the modulation technique applied during transmission of the signal. The receive chain may include at least one decoder for decoding the processing the demodulated signal to receive the transmitted data.

FIG. 9 illustrates an example of a processor 900 that supports multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure. The processor 900 may be an example of a processor configured to perform various operations in accordance with examples as described herein. For example, the device may be an example of the first UE 125 as described herein. The processor 900 may include a controller 902 configured to perform various operations in accordance with examples as described herein. The processor 900 may optionally include at least one memory 904, such as L1/L2/L3 cache. Additionally, or alternatively, the processor 900 may optionally include one or more arithmetic-logic units (ALUs) 906. One or more of these components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses) .

The processor 900 may be a processor chipset and include a protocol stack (e.g., a software stack) executed by the processor chipset to perform various operations (e.g., receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) in accordance with examples as described herein. The processor chipset may include one or more cores, one or more caches (e.g., memory local to or included in the processor chipset (e.g., the processor 900) or other memory (e.g., random access memory (RAM) , read-only memory (ROM) , dynamic RAM (DRAM) , synchronous dynamic RAM (SDRAM) , static RAM (SRAM) , ferroelectric RAM (FeRAM) , magnetic RAM (MRAM) , resistive RAM (RRAM) , flash memory, phase change memory (PCM) , and others) .

The controller 902 may be configured to manage and coordinate various operations (e.g., signaling, receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) of the processor 900 to cause the processor 900 to support various operations in accordance with examples as described herein. For example, the controller 902 may operate as a control unit of the processor 900, generating control signals that manage the operation of various components of the processor 900. These control signals include enabling or disabling functional units, selecting data paths, initiating memory access, and coordinating timing of operations.

The controller 902 may be configured to fetch (e.g., obtain, retrieve, receive) instructions from the memory 904 and determine subsequent instruction (s) to be executed to cause the processor 900 to support various operations in accordance with examples as described herein. The controller 902 may be configured to track memory address of instructions associated with the memory 904. The controller 902 may be configured to decode instructions to determine the operation to be performed and the operands involved. For example, the controller 902 may be configured to interpret the instruction and determine control signals to be output to other components of the processor 900 to cause the processor 900 to support various operations in accordance with examples as described herein. Additionally, or alternatively, the controller 902 may be configured to manage flow of data within the processor 900. The controller 902 may be configured to control transfer of data between registers, arithmetic logic units (ALUs) , and other functional units of the processor 900.

The memory 904 may include one or more caches (e.g., memory local to or included in the processor 900 or other memory, such RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc. In some implementation, the memory 904 may reside within or on a processor chipset (e.g., local to the processor 900) . In some other implementations, the memory 904 may reside external to the processor chipset (e.g., remote to the processor 900) .

The memory 904 may store computer-readable, computer-executable code including instructions that, when executed by the processor 900, cause the processor 900 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. The controller 902 and/or the processor 900 may be configured to execute computer-readable instructions stored in the memory 904 to cause the processor 900 to perform various functions. For example, the processor 900 and/or the controller 902 may be coupled with or to the memory 904, and the processor 900, the controller 902, and the memory 904 may be configured to perform various functions described herein. In some examples, the processor 900 may include multiple processors and the memory 904 may include multiple memories. One or more of the multiple processors may be coupled with one or more of the multiple memories, which may, individually or collectively, be configured to perform various functions herein.

The one or more ALUs 906 may be configured to support various operations in accordance with examples as described herein. In some implementation, the one or more ALUs 906 may reside within or on a processor chipset (e.g., the processor 900) . In some other implementations, the one or more ALUs 906 may reside external to the processor chipset (e.g., the processor 900) . One or more ALUs 906 may perform one or more computations such as addition, subtraction, multiplication, and division on data. For example, one or more ALUs 906 may receive input operands and an operation code, which determines an operation to be executed. One or more ALUs 906 be configured with a variety of logical and arithmetic circuits, including adders, subtractors, shifters, and logic gates, to process and manipulate the data according to the operation. Additionally, or alternatively, the one or more ALUs 906 may support logical operations such as AND, OR, exclusive-OR (XOR) , not-OR (NOR) , and not-AND (NAND) , enabling the one or more ALUs 906 to handle conditional operations, comparisons, and bitwise operations.

The processor 900 may support wireless communication in accordance with examples as disclosed herein. The processor 900 may be configured to or operable to support a means for multiple indirect paths in user equipment to network relay.

FIG. 10 illustrates an example of a processor 1000 that supports multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure. The processor 1000 may be an example of a processor configured to perform various operations in accordance with examples as described herein. For example, the device may be an example of the BS 122 as described herein. The processor 1000 may include a controller 1002 configured to perform various operations in accordance with examples as described herein. The processor 1000 may optionally include at least one memory 904, such as L1/L2/L3 cache. Additionally, or alternatively, the processor 900 may optionally include one or more arithmetic-logic units (ALUs) 1006. One or more of these components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses) .

The processor 1000 may be a processor chipset and include a protocol stack (e.g., a software stack) executed by the processor chipset to perform various operations (e.g., receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) in accordance with examples as described herein. The processor chipset may include one or more cores, one or more caches (e.g., memory local to or included in the processor chipset (e.g., the processor 1000) or other memory (e.g., random access memory (RAM) , read-only memory (ROM) , dynamic RAM (DRAM) , synchronous dynamic RAM (SDRAM) , static RAM (SRAM) , ferroelectric RAM (FeRAM) , magnetic RAM (MRAM) , resistive RAM (RRAM) , flash memory, phase change memory (PCM) , and others) .

The controller 1002 may be configured to manage and coordinate various operations (e.g., signaling, receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) of the processor 1000 to cause the processor 1000 to support various operations in accordance with examples as described herein. For example, the controller 1002 may operate as a control unit of the processor 1000, generating control signals that manage the operation of various components of the processor 1000. These control signals include enabling or disabling functional units, selecting data paths, initiating memory access, and coordinating timing of operations.

The controller 1002 may be configured to fetch (e.g., obtain, retrieve, receive) instructions from the memory 904 and determine subsequent instruction (s) to be executed to cause the processor 1000 to support various operations in accordance with examples as described herein. The controller 1002 may be configured to track memory address of instructions associated with the memory 1004. The controller 1002 may be configured to decode instructions to determine the operation to be performed and the operands involved. For example, the controller 1002 may be configured to interpret the instruction and determine control signals to be output to other components of the processor 1000 to cause the processor 1000 to support various operations in accordance with examples as described herein. Additionally, or alternatively, the controller 1002 may be configured to manage flow of data within the processor 1000. The controller 1002 may be configured to control transfer of data between registers, arithmetic logic units (ALUs) , and other functional units of the processor 1000.

The memory 1004 may include one or more caches (e.g., memory local to or included in the processor 1000 or other memory, such RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc. In some implementation, the memory 1004 may reside within or on a processor chipset (e.g., local to the processor 1000) . In some other implementations, the memory 904 may reside external to the processor chipset (e.g., remote to the processor 1000) .

The memory 1004 may store computer-readable, computer-executable code including instructions that, when executed by the processor 1000, cause the processor 1000 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. The controller 1002 and/or the processor 1000 may be configured to execute computer-readable instructions stored in the memory 1004 to cause the processor 1000 to perform various functions. For example, the processor 1000 and/or the controller 1002 may be coupled with or to the memory 1004, and the processor 1000, the controller 1002, and the memory 1004 may be configured to perform various functions described herein. In some examples, the processor 1000 may include multiple processors and the memory 1004 may include multiple memories. One or more of the multiple processors may be coupled with one or more of the multiple memories, which may, individually or collectively, be configured to perform various functions herein.

The one or more ALUs 1006 may be configured to support various operations in accordance with examples as described herein. In some implementation, the one or more ALUs 906 may reside within or on a processor chipset (e.g., the processor 1000) . In some other implementations, the one or more ALUs 1006 may reside external to the processor chipset (e.g., the processor 1000) . One or more ALUs 1006 may perform one or more computations such as addition, subtraction, multiplication, and division on data. For example, one or more ALUs 1006 may receive input operands and an operation code, which determines an operation to be executed. One or more ALUs 1006 be configured with a variety of logical and arithmetic circuits, including adders, subtractors, shifters, and logic gates, to process and manipulate the data according to the operation. Additionally, or alternatively, the one or more ALUs 1006 may support logical operations such as AND, OR, exclusive-OR (XOR) , not-OR (NOR) , and not-AND (NAND) , enabling the one or more ALUs 1006 to handle conditional operations, comparisons, and bitwise operations.

The processor 1000 may support wireless communication in accordance with examples as disclosed herein. The processor 1000 may be configured to or operable to support a means for multiple indirect paths in user equipment to network relay.

FIG. 11 illustrates a flowchart of a method 1100 that supports multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure. The operations of the method 1100 may be implemented by a device or its components as described herein. For example, the operations of the method 1100 may be performed by the first user equipment 125 as described herein. In some implementations, the device may execute a set of instructions to control the function elements of the device to perform the described functions. Additionally, or alternatively, the device may perform aspects of the described functions using special-purpose hardware.

At 1110, the method may include receiving via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) . The operations of 1110 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 1110 may be performed by a device as described with reference to FIG. 1A or FIG. 1B.

At 1120, the method may include managing via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay. The operations of 1110 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 1110 may be performed by a device as described with reference to FIG. 1A or FIG. 1B.

FIG. 12 illustrates a flowchart of a method 1200 that supports multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure. The operations of the method 1200 may be implemented by a device or its components as described herein. For example, the operations of the method 1200 may be performed by the first user equipment 125 as described herein. In some implementations, the device may execute a set of instructions to control the function elements of the device to perform the described functions. Additionally, or alternatively, the device may perform aspects of the described functions using special-purpose hardware.

At 1210, the method may include determining whether a condition for activating an indirect path among the plurality indirect paths other than the first indirect path. The operations of 1210 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 1210 may be performed by a device as described with reference to FIG. 1A or FIG. 1B.

At 1220, the method may include based on determining that the condition is met, activating a second indirect path among the plurality indirect paths. The operations of 1220 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 1220 may be performed by a device as described with reference to FIG. 1A or FIG. 1B.

FIG. 13 illustrates a flowchart of a method 1300 that supports multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure. The operations of the method 1300 may be implemented by a device or its components as described herein. For example, the operations of the method 1300 may be performed by the BS 122 as described herein. In some implementations, the device may execute a set of instructions to control the function elements of the device to perform the described functions. Additionally, or alternatively, the device may perform aspects of the described functions using special-purpose hardware.

At 1310, the method may include transmitting via the transceiver, a configuration for a plurality of indirect paths between a first user equipment (UE) and the BS. The operations of 1310 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 1310 may be performed by a device as described with reference to FIG. 1A or FIG. 1B.

At 1320, the method may include managing via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay. The operations of 1320 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 1320 may be performed by a device as described with reference to FIG. 1A or FIG. 1B.

FIG. 14 illustrates a flowchart of a method 1400 that supports multiple indirect paths in user equipment to network relay in accordance with aspects of the present disclosure. The operations of the method 1400 may be implemented by a device or its components as described herein. For example, the operations of the method 1400 may be performed by the BS 122 as described herein. In some implementations, the device may execute a set of instructions to control the function elements of the device to perform the described functions. Additionally, or alternatively, the device may perform aspects of the described functions using special-purpose hardware.

At 1410, the method may include transmitting, via the transceiver and to the first UE, a condition for activating an indirect path among the plurality indirect paths other than the first indirect path. The operations of 1410 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 1410 may be performed by a device as described with reference to FIG. 1A or FIG. 1B.

It should be noted that the methods described herein describes possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined.

The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, 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 processor, controller, micro-controller, 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, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special-purpose computer. By way of example, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM) , flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.

As used herein, including in the claims, an article “a” before an element is unrestricted and understood to refer to “at least one” of those elements or “one or more” of those elements. The terms “a, ” “at least one, ” “one or more, ” and “at least one of one or more” may be interchangeable. As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of” or “one or both of” ) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) . Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. Further, as used herein, including in the claims, a “set” may include one or more elements.

The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

In summary, embodiments of the present disclosure may provide the following solutions.

Clause 1. A first user equipment (UE) comprising: a processor; and a transceiver coupled to the processor, wherein the processor is configured to: receive via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) ; and manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

Clause 2. The first UE of Clause 1, wherein managing the first indirect path comprises: receiving, via the transceiver and from the BS, an indication for activating the first indirect path via a medium access control (MAC) control element (CE) through a direct path between the first UE and the BS.

Clause 3. The first UE of Clause 2, wherein the indication is a first indication, and the processor is further configured to: based on receiving the first indication via the MAC CE, transmit, via the transceiver to the second UE, a second indication that the first indirect path is activated.

Clause 4. The first UE of Clause 1, wherein managing the first indirect path comprises: receiving, via the transceiver and from the second UE, an indication for activating the first indirect path via RRC message.

Clause 5. The first UE of Clause 3 and Clause 4, wherein the indication comprises one of the following: an identifier (ID) of the second UE, a path index of the first indirect path, or an index of the first indirect path among the plurality of indirect paths.

Clause 6. The first UE of Clause 1, wherein the processor is further configured to: determine whether a condition for a change of an activated indirect path is met; based on determining that the condition is met, activate a second indirect path among the plurality indirect paths; and deactivate the first indirect path.

Clause 7. The first UE of Clause 6, wherein the condition comprises one of the following: a first link quality of a PC5 link of the first indirect path is less than a first quality threshold and a second link quality of a PC5 link of the second indirect path is greater than a second quality threshold; a third link quality of the PC5 link of the second indirect path becomes offset better than a fourth link quality of the PC5 link of the first indirect path; or the fifth link quality of the PC5 link of the first indirect path is less than a third quality threshold.

Clause 8. The first UE of Clause 1, wherein the processor is further configured to: determine whether a condition for activating an indirect path among the plurality indirect paths other than the first indirect path; and based on determining that the condition is met, activate a second indirect path among the plurality indirect paths.

Clause 9. The first UE of Clause 8, wherein the processor is further configured to: transmit, via the transceiver and to the BS, an indication that the first indirect path fails and the second indirect path is activated.

Clause 10. The first UE of Clause 8, wherein the condition comprises one of the following: a radio link failure (RLF) in a sidelink link of the first indirect path between the first UE and the second UE is detected; or a failure notification message or a release message is received from the second UE in the first indirect path.

Clause 11. The first UE of Clause 1, wherein one or more indirect paths among the plurality indirect paths other than the first indirect path are deactivated.

Clause 12. The first UE of Clause 11, wherein for the second indirect path among the one or more indirect paths which are deactivated: both of the first UE and a third UE acting as a relay in the second indirect path maintain a sidelink radio resource control (RRC) connection between the first UE and the third UE; one of the first UE and the third UE monitors the sidelink RRC connection wherein the other one is allowed to stop monitoring the sidelink RRC connection; the third UE avoids transmitting a failure notification message or a release message due to a handover or a RLF of the third UE; or in the case that the first UE receives the failure notification message or the release message from the third UE, the first UE avoids triggering a failure report.

Clause 13. The first UE of Clause 1, wherein: a direct path is established and activated between the first UE and the BS; and the plurality of indirect paths including the first indirect path are activated.

Clause 14. The first UE of Clause 13, wherein the processor is further configured to: based on detecting an RLF in the direct path, transmit, via the transceiver and to the BS, a failure message for the direct path via a first indirect path among the plurality of indirect paths, wherein the first indirect path is configured with a signaling radio bearer (SRB) or a split SRB.

Clause 15. The first UE of Clause 14, wherein the first indirect path is one of multiple indirect paths configured with a SRB or a split SRB, and the first indirect path is selected from the multiple indirect paths based on one of the following: a configuration from the BS; a UE implementation; or channel qualities of the multiple indirect paths.

Clause 16. The first UE of Clause 14, wherein the failure message for the direct path is a first failure message, and the processor is further configured to: suspend the first indirect path based on detecting a RLF of the PC5 link in the first indirect path or receiving a failure notification message or a release message from the second UE in the first indirect path, prior to receiving, from the BS, a response to the first failure message; and transmit, via the transceiver and to the BS, a second failure message for the first indirect path via a second indirect path among the multiple indirect paths configured with a SRB or a split SRB.

Clause 17. The first UE of Clause 16, wherein the processor is further configured to: based on determining that the direct path and the multiple indirect paths are configured with a SRB or a split SRB fail, initiate a reestablishment procedure with the BS.

Clause 18. The first UE of Clause 1, wherein the processor is further configured to: based on determining that an amount of buffered data at the first UE is greater than an amount threshold, activate a second indirect path among the plurality indirect paths; and maintain the first indirect path to be activated.

Clause 19. The first UE of Clause 18, wherein the processor is further configured to: transmit, via the transceiver and to the BS, the buffered data via one of the following: a direct path, the first indirect path, and the second indirect path; or the first indirect path and the second indirect path.

Clause 20. A base station (BS) comprising: a processor; and a transceiver coupled to the processor, wherein the processor is configured to: transmit via the transceiver, a configuration for a plurality of indirect paths between a first user equipment (UE) and the BS; and manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

Clause 21. The BS of Clause 20, wherein managing the first indirect path comprises: transmitting, via the transceiver and to the first UE, an indication for activating the first indirect path via a medium access control (MAC) control element (CE) through a direct path between the first UE and the BS.

Clause 22. The BS of Clause 20, wherein managing the first indirect path comprises: transmitting, via the transceiver and to the second UE, an indication for activating the first indirect path via RRC message.

Clause 23. The BS of Clause 21 and Clause 22, wherein the indication comprises one of the following: an identifier (ID) of the second UE, a path index of the first indirect path, or an index of the first indirect path among the plurality of indirect paths.

Clause 24. The BS of Clause 20, wherein the processor is further configured to: transmit, via the transceiver and to the first UE, a condition for triggering a change of an activated indirect path.

Clause 25. The BS of Clause 24, wherein the condition comprises one of the following: a first link quality of a PC5 link of the first indirect path is less than a first quality threshold and a second link quality of a PC5 link of a second indirect path among the plurality indirect paths is greater than a second quality threshold; a third link quality of the PC5 link of the second indirect path becomes offset better than a fourth link quality of the PC5 link of the first indirect path; or the fifth link quality of the PC5 link of the first indirect path is less than a third quality threshold.

Clause 26. The BS of Clause 20, wherein the processor is further configured to: transmit, via the transceiver and to the first UE, a condition for activating an indirect path among the plurality indirect paths other than the first indirect path.

Clause 27. The BS of Clause 26, wherein the processor is further configured to: receive, via the transceiver and from the first UE, an indication that the first indirect path fails and a second indirect path among the plurality indirect paths is activated.

Clause 28. The BS of Clause 26, wherein the condition comprises one of the following: a radio link failure (RLF) in a sidelink link of the first indirect path between the first UE and the second UE is detected; or a failure notification message or a release message is received from the second UE in the first indirect path.

Clause 29. The BS of Clause 20, wherein one or more indirect paths among the plurality indirect paths other than the first indirect path are deactivated.

Clause 30. The BS of Clause 29, wherein for the second indirect path among the one or more indirect paths which are deactivated: both of the first UE and a third UE acting as a relay in the second indirect path maintain a sidelink radio resource control (RRC) connection between the first UE and the third UE; one of the first UE and the third UE monitors the sidelink RRC connection wherein the other one is allowed to stop monitoring the sidelink RRC connection; the third UE avoids transmitting a failure notification message or a release message due to a handover or a RLF of the third UE; or in the case that the first UE receives the failure notification message or the release message from the third UE, the first UE avoids triggering a failure report.

Clause 31. The BS of Clause 20, wherein: a direct path is established and activated between the first UE and the BS; and the plurality of indirect paths including the first indirect path are activated.

Clause 32. The BS of Clause 31, wherein the processor is further configured to: in the case of an RLF in the direct path, receive, via the transceiver and from the first UE, a failure message for the direct path via a second indirect path among the plurality of indirect paths, wherein the second indirect path is configured with a signaling radio bearer (SRB) or a split SRB.

Clause 33. The BS of Clause 32, wherein the second indirect path is one of multiple indirect paths configured with a SRB or a split SRB, and the second indirect path is selected from the multiple indirect paths based on one of the following: a configuration from the BS; a UE implementation; or channel qualities of the multiple indirect paths.

Clause 34. The BS of Clause 32, wherein the failure message for the direct path is a first failure message, and the processor is further configured to: in the case that a RLF of the PC5 link in the second indirect path is detected or a failure notification message or a release message is transmitted in the second indirect path prior to transmitting, to the first UE, a response to the first failure message, receive, via the transceiver and from the first UE, a second failure message for the second indirect path via a third indirect path among the multiple indirect paths configured with a SRB or a split SRB.

Clause 35. The BS of Clause 20, wherein the processor is further configured to: transmit, via the transceiver and to the first UE, an amount threshold for comparing with an amount of buffered data at the first UE to determine whether to activate a second indirect path among the plurality indirect paths in addition to the first indirect path which is maintained to be activated.

Clause 36. The BS of Clause 35, wherein the processor is further configured to: receive, via the transceiver and from the first UE, the buffered data via one of the following: a direct path, the first indirect path, and the second indirect path; or the first indirect path and the second indirect path.

Clause 37. A processor for wireless communication, comprising: at least one memory; and a controller coupled with the at least one memory and configured to cause the controller to: receive via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) ; manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

Clause 38. A processor for wireless communication, comprising: at least one memory; and a controller coupled with the at least one memory and configured to cause the controller to: transmit via the transceiver, a configuration for a plurality of indirect paths between a first user equipment (UE) and the BS; manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

Clause 39. A method performed by a user equipment (UE) , the method comprising: receiving via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) ; managing via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

Clause 40. A method performed by a base station (BS) , the method comprising:

transmitting via the transceiver, a configuration for a plurality of indirect paths between a first user equipment (UE) and the BS; managing via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.

Clause 41. A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform the method of Clause 39 or 40.

Claims

A first user equipment (UE) comprising:

a processor; and

a transceiver coupled to the processor,

wherein the processor is configured to:

receive via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) ; and

manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.
The first UE of claim 1, wherein managing the first indirect path comprises:

receiving, via the transceiver and from the BS, an indication for activating the first indirect path via a medium access control (MAC) control element (CE) through a direct path between the first UE and the BS.
The first UE of claim 2, wherein the indication is a first indication, and the processor is further configured to:

based on receiving the first indication via the MAC CE, transmit, via the transceiver to the second UE, a second indication that the first indirect path is activated.
The first UE of claim 1, wherein managing the first indirect path comprises:

receiving, via the transceiver and from the second UE, an indication for activating the first indirect path via RRC message.
The first UE of claim 3 and claim4, wherein the indication comprises one of the following:

an identifier (ID) of the second UE,

a path index of the first indirect path, or

an index of the first indirect path among the plurality of indirect paths.
The first UE of claim 1, wherein the processor is further configured to:

determine whether a condition for a change of an activated indirect path is met;

based on determining that the condition is met, activate a second indirect path among the plurality indirect paths; and

deactivate the first indirect path.
The first UE of claim 6, wherein the condition comprises one of the following:

a first link quality of a PC5 link of the first indirect path is less than a first quality threshold and a second link quality of a PC5 link of the second indirect path is greater than a second quality threshold;

a third link quality of the PC5 link of the second indirect path becomes offset better than a fourth link quality of the PC5 link of the first indirect path; or

the fifth link quality of the PC5 link of the first indirect path is less than a third quality threshold.
The first UE of claim 1, wherein the processor is further configured to:

determine whether a condition for activating an indirect path among the plurality indirect paths other than the first indirect path; and

based on determining that the condition is met, activate a second indirect path among the plurality indirect paths.
The first UE of claim 8, wherein the processor is further configured to:

transmit, via the transceiver and to the BS, an indication that the first indirect path fails and the second indirect path is activated.
The first UE of claim 8, wherein the condition comprises one of the following:

a radio link failure (RLF) in a sidelink link of the first indirect path between the first UE and the second UE is detected; or

a failure notification message or a release message is received from the second UE in the first indirect path.
The first UE of claim 1, wherein one or more indirect paths among the plurality indirect paths other than the first indirect path are deactivated.
The first UE of claim 11, wherein for the second indirect path among the one or more indirect paths which are deactivated:

both of the first UE and a third UE acting as a relay in the second indirect path maintain a sidelink radio resource control (RRC) connection between the first UE and the third UE;

one of the first UE and the third UE monitors the sidelink RRC connection, wherein the other one is allowed to stop monitoring the sidelink RRC connection;

the third UE avoids transmitting a failure notification message or a release message due to a handover or a RLF of the third UE; or

in the case that the first UE receives the failure notification message or the release message from the third UE, the first UE avoids triggering a failure report.
The first UE of claim 1, wherein:

a direct path is established and activated between the first UE and the BS; and

the plurality of indirect paths including the first indirect path are activated.
The first UE of claim 13, wherein the processor is further configured to:

based on detecting an RLF in the direct path, transmit, via the transceiver and to the BS, a failure message for the direct path via a first indirect path among the plurality of indirect paths, wherein the first indirect path is configured with a signaling radio bearer (SRB) or a split SRB.
The first UE of claim 14, wherein the first indirect path is one of multiple indirect paths configured with a SRB or a split SRB, and the first indirect path is selected from the multiple indirect paths based on one of the following:

a configuration from the BS;

a UE implementation; or

channel qualities of the multiple indirect paths.
The first UE of claim 14, wherein the failure message for the direct path is a first failure message, and the processor is further configured to:

suspend the first indirect path based on detecting a RLF of the PC5 link in the first indirect path or receiving a failure notification message or a release message from the second UE in the first indirect path, prior to receiving, from the BS, a response to the first failure message; and

transmit, via the transceiver and to the BS, a second failure message for the first indirect path via a second indirect path among the multiple indirect paths configured with a SRB or a split SRB.
The first UE of claim 16, wherein the processor is further configured to:

based on determining that the direct path and the multiple indirect paths are configured with a SRB or a split SRB fail, initiate a reestablishment procedure with the BS.
The first UE of claim 1, wherein the processor is further configured to:

based on determining that an amount of buffered data at the first UE is greater than an amount threshold, activate a second indirect path among the plurality indirect paths; and

maintain the first indirect path to be activated.
The first UE of claim 18, wherein the processor is further configured to:

transmit, via the transceiver and to the BS, the buffered data via one of the following:

a direct path, the first indirect path, and the second indirect path; or

the first indirect path and the second indirect path.
A base station (BS) comprising:

a processor; and

a transceiver coupled to the processor,

wherein the processor is configured to:

transmit via the transceiver, a configuration for a plurality of indirect paths between a first user equipment (UE) and the BS; and

manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.
The BS of claim 20, wherein managing the first indirect path comprises:

transmitting, via the transceiver and to the first UE, an indication for activating the first indirect path via a medium access control (MAC) control element (CE) through a direct path between the first UE and the BS.
The BS of claim 20, wherein managing the first indirect path comprises:

transmitting, via the transceiver and to the second UE, an indication for activating the first indirect path via RRC message.
The BS of claim 21 and claim22, wherein the indication comprises one of the following:

an identifier (ID) of the second UE,

a path index of the first indirect path, or

an index of the first indirect path among the plurality of indirect paths.
The BS of claim 20, wherein the processor is further configured to:

transmit, via the transceiver and to the first UE, a condition for triggering a change of an activated indirect path.
The BS of claim 24, wherein the condition comprises one of the following:

a first link quality of a PC5 link of the first indirect path is less than a first quality threshold and a second link quality of a PC5 link of a second indirect path among the plurality indirect paths is greater than a second quality threshold;

a third link quality of the PC5 link of the second indirect path becomes offset better than a fourth link quality of the PC5 link of the first indirect path; or

the fifth link quality of the PC5 link of the first indirect path is less than a third quality threshold.
The BS of claim 20, wherein the processor is further configured to:

transmit, via the transceiver and to the first UE, a condition for activating an indirect path among the plurality indirect paths other than the first indirect path.
The BS of claim 26, wherein the processor is further configured to:

receive, via the transceiver and from the first UE, an indication that the first indirect path fails and a second indirect path among the plurality indirect paths is activated.
The BS of claim 26, wherein the condition comprises one of the following:

a radio link failure (RLF) in a sidelink link of the first indirect path between the first UE and the second UE is detected; or

a failure notification message or a release message is received from the second UE in the first indirect path.
The BS of claim 20, wherein one or more indirect paths among the plurality indirect paths other than the first indirect path are deactivated.
The BS of claim 29, wherein for the second indirect path among the one or more indirect paths which are deactivated:

both of the first UE and a third UE acting as a relay in the second indirect path maintain a sidelink radio resource control (RRC) connection between the first UE and the third UE;

one of the first UE and the third UE monitors the sidelink RRC connection, wherein the other one is allowed to stop monitoring the sidelink RRC connection;

the third UE avoids transmitting a failure notification message or a release message due to a handover or a RLF of the third UE; or

in the case that the first UE receives the failure notification message or the release message from the third UE, the first UE avoids triggering a failure report.
The BS of claim 20, wherein:

a direct path is established and activated between the first UE and the BS; and

the plurality of indirect paths including the first indirect path are activated.
The BS of claim 31, wherein the processor is further configured to:

in the case of an RLF in the direct path, receive, via the transceiver and from the first UE, a failure message for the direct path via a second indirect path among the plurality of indirect paths, wherein the second indirect path is configured with a signaling radio bearer (SRB) or a split SRB.
The BS of claim 32, wherein the second indirect path is one of multiple indirect paths configured with a SRB or a split SRB, and the second indirect path is selected from the multiple indirect paths based on one of the following:

a configuration from the BS;

a UE implementation; or

channel qualities of the multiple indirect paths.
The BS of claim 32, wherein the failure message for the direct path is a first failure message, and the processor is further configured to:

in the case that a RLF of the PC5 link in the second indirect path is detected or a failure notification message or a release message is transmitted in the second indirect path prior to transmitting, to the first UE, a response to the first failure message, receive, via the transceiver and from the first UE, a second failure message for the second indirect path via a third indirect path among the multiple indirect paths configured with a SRB or a split SRB.
The BS of claim 20, wherein the processor is further configured to:

transmit, via the transceiver and to the first UE, an amount threshold for comparing with an amount of buffered data at the first UE to determine whether to activate a second indirect path among the plurality indirect paths in addition to the first indirect path which is maintained to be activated.
The BS of claim 35, wherein the processor is further configured to:

receive, via the transceiver and from the first UE, the buffered data via one of the following:

a direct path, the first indirect path, and the second indirect path; or

the first indirect path and the second indirect path.
A processor for wireless communication, comprising:

at least one memory; and

a controller coupled with the at least one memory and configured to cause the controller to:

receive via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) ;

manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.
A processor for wireless communication, comprising:

at least one memory; and

a controller coupled with the at least one memory and configured to cause the controller to:

transmit via the transceiver, a configuration for a plurality of indirect paths between a first user equipment (UE) and the BS;

manage via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.
A method performed by a user equipment (UE) , the method comprising:

receiving via the transceiver, a configuration for a plurality of indirect paths between the first UE and a base station (BS) ;

managing via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.
A method performed by a base station (BS) , the method comprising:

transmitting via the transceiver, a configuration for a plurality of indirect paths between a first user equipment (UE) and the BS;

managing via the transceiver, a first indirect path among the plurality of indirect paths, wherein data is transmitted in the first indirect path between the first UE and the BS via a second UE acting as a relay.
A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform the method of claim 39 or 40.