WO2025097794A1

WO2025097794A1 - Sib acquisition in relay communication

Info

Publication number: WO2025097794A1
Application number: PCT/CN2024/101726
Authority: WO
Inventors: Lianhai WU; Ran YUE; Jing HAN
Original assignee: Lenovo Beijing Ltd
Current assignee: Lenovo Beijing Ltd
Priority date: 2024-06-26
Filing date: 2024-06-26
Publication date: 2025-05-15
Anticipated expiration: 2026-12-26

Abstract

Example embodiments of the present disclosure relate to a first UE, a second UE, a BS, methods, apparatuses, processors, and computer readable medium for SIB acquisition for a remote UE. In the solution, the first UE receives a first request for a first SIB list from a remote UE in an idle or inactive state, where the remote UE accesses a base station via multiple UEs at least including the first UE and a second UE. The first UE transmits a second request for a second SIB list to the second UE and receives, from the second UE, a third SIB list based on the second request. In addition, the first UE transmits a fourth SIB list to the remote UE, where the fourth SIB list may be based on the third SIB list and the first request. As such, for a remote accessing a base station via multiple relay UEs, a procedure is defined for obtaining the SIB list of the remote UE.

Description

SIB ACQUISITION IN RELAY COMMUNICATION

TECHNICAL FIELD

The present disclosure relates to wireless communications, and more specifically to user equipment (UE) , a base station (BS) , methods, apparatuses, processors, and computer readable medium for system information block (SIB) acquisition in a relay communication.

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) ) .

A scenario of UE-to-network (U2N) relay has been discussed in the third generation partner project (3GPP) . An indirect path is a type of U2N transmission path, where data is forwarded via at least one U2N relay UE between a U2N remote UE and the network. In case there are two or more than two relay UEs between the remote UE and the network, an issue of SIB acquisition should be studied.

SUMMARY

The present disclosure relates to a first UE, a second UE, a BS, methods, apparatuses, processors, and computer readable medium for SIB acquisition for a remote UE. According to the proposed solution, one or more relay UE may be used for obtaining a SIB list for a remote UE which accesses a base station via multiple relay UEs.

In some implementations, there is provided a first UE. The first UE comprises at least one memory; and at least one processor coupled with the at least one memory and configured to cause the first UE to: receive, from a remote UE in an idle or inactive state, a first request for a first SIB list of the remote UE, wherein the remote UE accesses a base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and a second UE; transmit, to the second UE, a second request for a second SIB list of the remote UE and the first UE; receive, from the second UE, a third SIB list based on the second request; and transmit, to the remote UE, a fourth SIB list of the remote UE based on the third SIB list.

In some implementations, there is provided a second UE. The second UE comprises at least one memory; and at least one processor coupled with the at least one memory and configured to cause the second UE to: receive, from a first UE, a request for a first SIB list related to at least a remote UE and the first UE, wherein the remote UE accesses a base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and the second UE; and transmit, to the first UE, a second SIB list based on the request.

In some implementations, there is provided a BS. The BS comprises at least one memory; and at least one processor coupled with the at least one memory and configured to cause the BS to: determine a configuration for a SIB acquisition associated with a remote UE; and transmit, to at least a first UE or a second UE, the configuration indicating a UE responsible for SIB acquisition, wherein the remote UE accesses the base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and the second UE.

In some implementations, there is provided a method performed by the first UE. The method comprises: receiving, from a remote UE in an idle or inactive state, a first request for a first SIB list of the remote UE, wherein the remote UE accesses a base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and a second UE; transmitting, to the second UE, a second request for a second SIB list of the remote UE and the first UE; receiving, from the second UE, a third SIB list based on the second request; and transmitting, to the remote UE, a fourth SIB list of the remote UE based on the third SIB list.

In some implementations, there is provided a method performed by the second UE. The method comprises: receiving, from a first UE, a request for a first SIB list related to at least a remote UE and the first UE, wherein the remote UE accesses a base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and the second UE; and transmitting, to the first UE, a second SIB list based on the request.

In some implementations, there is provided a method performed by the BS. The method comprises: determining a configuration for a SIB acquisition associated with a remote UE; and transmitting, to at least a first UE or a second UE, the configuration indicating a UE responsible for SIB acquisition, wherein the remote UE accesses the base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and the second UE.

In some implementations, there is provided a processor for wireless communication. The processor comprises at least one controller coupled with at least one memory and configured to cause the processor to: receive, from a remote UE in an idle or inactive state, a first request for a first SIB list of the remote UE, wherein the remote UE accesses a base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and a second UE; transmit, to the second UE, a second request for a second SIB list of the remote UE and the first UE; receive, from the second UE, a third SIB list based on the second request; and transmit, to the remote UE, a fourth SIB list of the remote UE based on the third SIB list.

In some implementations, there is provided a processor for wireless communication. The processor comprises at least one controller coupled with at least one memory and configured to cause the processor to: receive, from a first UE, a request for a first SIB list related to at least a remote UE and the first UE, wherein the remote UE accesses a base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and the second UE; and transmit, to the first UE, a second SIB list based on the request.

In some implementations, there is provided a processor for wireless communication. The processor comprises at least one controller coupled with at least one memory and configured to cause the processor to: determine a configuration for a SIB acquisition associated with a remote UE; and transmit, to at least a first UE or a second UE, the configuration indicating a UE responsible for SIB acquisition, wherein the remote UE accesses the base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and the second UE.

In some implementations of the methods, the first UE, and the second UE described herein, further comprising: receiving, from the base station, a configuration indicating that one of the first UE, the second UE, or a third UE is a UE responsible for SIB acquisition.

In some implementations of the methods and the first UE described herein, further comprising: performing an on-demand SIB acquisition procedure to obtain the first SIB list based on one of: the first UE is in coverage of the base station, the first UE is in a connected state, the first UE is configured as a UE responsible for SIB acquisition, or the first UE is meeting a condition of SIB acquisition, wherein the condition is configured by the base station.

In some implementations of the methods and the first UE described herein, further comprising: in accordance with one of the following conditions is met, triggering a transmission of the second request: the first UE moves to an idle or inactive state and out of the coverage, the first UE moves from in coverage of the base station to out of the coverage, the first UE in the coverage transits from a connected state to an idle or inactive state, or the first UE transits from the connected state to an idle or inactive state out of the coverage.

In some implementations of the methods and the first UE described herein, further comprising: in accordance with one of the following conditions is met, transmitting, to the second UE, a message for stopping acquiring the second SIB list: the first UE moves from out of coverage of the base station to in coverage, the first UE in the coverage transits from an idle or inactive state to a connected state, or the first UE transits from an idle or inactive state out of the coverage to the connected state in coverage. In some examples, the message comprises a value for requesting SIB which is set as release.

In some implementations of the methods and the first UE described herein, further comprising: initiating a Uu message transfer procedure based one of: receiving the first SIB list of the remote UE, receiving an update of the first SIB list, receiving an unsolicited SIB1 from the second UE, or receiving an updated SIB1.

In some implementations of the methods and the second UE described herein, further comprising: transmitting, to a third UE, a further request for a third SIB list related to at least the remote UE, the first UE, and the second UE based on one of: the second UE is out of coverage of the base station, the second UE is out of coverage of the base station, wherein the first UE is idle or inactive state, the second UE is not configured as a UE responsible for SIB acquisition, or the second UE is not meeting a condition of SIB acquisition which is configured by the base station; and receiving, from the third UE, a fourth SIB list based on the further request, wherein the multiple UEs comprises the third UE, and wherein there is a proximity communication 5 (PC5) connection between the second UE and the third UE. In some examples, there is a PC5 connection between the remote UE and the first UE, or there is a further UE between the remote UE and the first UE.

In some implementations of the methods and the second UE described herein, further comprising: in accordance with one of the following conditions is met, triggering a transmission of the further request to the third UE: the second UE moves from in coverage of the base station to out of the coverage, the second UE in the coverage transits from a connected state to an idle or inactive state, or the second UE transits from the connected state to an idle or inactive state out of the coverage.

In some implementations of the methods and the second UE described herein, further comprising: in accordance with one of the following conditions is met, transmitting, to the third UE, a message for stopping acquiring the third SIB list: the second UE moves from out of coverage of the base station to in coverage, the second UE in the coverage transits from an idle or inactive state to a connected state, or the second UE transits from an idle or inactive state out of the coverage to the connected state in coverage. In some examples, the message comprises a value for requesting SIB which is set as release.

In some implementations of the methods and the second UE described herein, further comprising: performing an on-demand SIB acquisition procedure to obtain the second SIB list based on one of: there is a Uu connection between the second UE and the base station, the second UE is in coverage of the base station, the second UE is in a connected state, the second UE is configured as a UE responsible for SIB acquisition, or the second UE is meeting a condition of SIB acquisition, wherein the condition is configured by the base station.

In some implementations of the methods, the first UE, the second UE, and the BS described herein, the second request from the first UE to the second UE is transmitted based on one of: the first UE is out of coverage of the base station, the first UE is out of coverage of the base station, wherein the first UE is idle or inactive state, the first UE is not configured as a UE responsible for SIB acquisition, or the first UE is not meeting a condition of SIB acquisition, wherein the condition is configured by the base station.

In some implementations of the methods, the first UE, the second UE, and the BS described herein, the configuration is further transmitted to the remote UE.

In some implementations of the methods, the first UE, the second UE, and the BS described herein, there is a PC5 connection between the remote UE and the first UE.

In some implementations of the methods, the first UE, the second UE, and the BS described herein, there is a PC5 connection between the first UE and the second UE.

In some implementations of the methods, the first UE, the second UE, and the BS described herein, the second UE accesses the base station via a direct path or at least a third UE.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communications system in which some embodiments of the present disclosure can be implemented;

FIG. 2A illustrates a schematic diagram of an example communication network in which some embodiments of the present disclosure can be implemented;

FIG. 2B illustrates a schematic diagram of an example communication network of a U2N relay;

FIG. 2C illustrates a schematic diagram of an example communication network in which some embodiments of the present disclosure can be implemented;

FIG. 3 illustrates a signalling chart illustrating communication process in accordance with some example embodiments of the present disclosure;

FIG. 4 illustrates a signalling chart illustrating communication process in accordance with some example embodiments of the present disclosure;

FIG. 5 illustrates an example of a device that is suitable for implementing embodiments of the present disclosure;

FIG. 6 illustrates an example of a processor that is suitable for implementing some embodiments of the present disclosure;

FIG. 7 illustrates a flowchart of an example method implemented at a first UE in accordance with aspects of the present disclosure;

FIG. 8 illustrates a flowchart of an example method implemented at a second UE in accordance with aspects of the present disclosure; and

FIG. 9 illustrates a flowchart of an example method implemented at a BS in accordance with aspects of the present disclosure.

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

DETAILED DESCRIPTION

Principles of the present disclosure will now be described with reference to some 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 example embodiment, ” “an embodiment, ” “some embodiments, ” and the like indicate that the embodiment (s) 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 do not necessarily refer to the same embodiment (s) . 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” or the like 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 element. For example, a first element could also be termed as a second element, and similarly, a second element could also be termed as a first element, without departing from the scope of embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms. In some examples, values, procedures, or apparatuses are referred to as “best, ” “lowest, ” “highest, ” “minimum, ” “maximum, ” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of 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, components and/or the like, but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. For example, the term “includes” and its variants are to be read as open terms that mean “includes, but is not limited to. ” The term “based on” is to be read as “based at least in part on. ” The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment. ” The term “another embodiment” is to be read as “at least one other embodiment. ” The use of an expression such as “Aand/or B” can mean either “only A” or “only B” or “both A and B. ” Other definitions, explicit and implicit, may be included below.

FIG. 1 illustrates an example of a wireless communications system 100 in which some embodiments of the present disclosure can be implemented. 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 (CN) 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 a long term evolution (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 a new radio (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, message, 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 CN 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 (SL) . 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 CN 106, or with another network entity 102, or both. For example, a network entity 102 may interface with the CN 106 through one or more backhaul links 116 (e.g., via an S1, N2, N3, 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 CN 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.

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 CN 106 may support user authentication, access authorization, tracking, connectivity, and other access, routing, or mobility functions. The CN 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 CN 106.

The CN 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 CN 106 via a network entity 102. The CN 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 CN 106 (e.g., one or more network functions of the CN 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.

One or more numerologies may be supported in the wireless communications system 100, and a numerology may include a subcarrier spacing and a cyclic prefix. A first numerology (e.g., μ=0) may be associated with a first subcarrier spacing (e.g., 15 kHz) and a normal cyclic prefix. In some implementations, the first numerology (e.g., μ=0) associated with the first subcarrier spacing (e.g., 15 kHz) may utilize one slot per subframe. A second numerology (e.g., μ=1) may be associated with a second subcarrier spacing (e.g., 30 kHz) and a normal cyclic prefix. A third numerology (e.g., μ=2) may be associated with a third subcarrier spacing (e.g., 60 kHz) and a normal cyclic prefix or an extended cyclic prefix. A fourth numerology (e.g., μ=3) may be associated with a fourth subcarrier spacing (e.g., 120 kHz) and a normal cyclic prefix. A fifth numerology (e.g., μ=4) may be associated with a fifth subcarrier spacing (e.g., 240 kHz) and a normal cyclic prefix.

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.

Additionally or alternatively, a time interval of a resource (e.g., a communication resource) may be organized according to slots. For example, a subframe may include a number (e.g., quantity) of slots. The number of slots in each subframe may also depend on the one or more numerologies supported in the wireless communications system 100. For instance, the first, second, third, fourth, and fifth numerologies (i.e., μ=0, μ=1, μ=2, μ=3, μ=4) associated with respective subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz may utilize a single slot per subframe, two slots per subframe, four slots per subframe, eight slots per subframe, and 16 slots per subframe, respectively. Each slot may include a number (e.g., quantity) of symbols (e.g., OFDM symbols) . In some implementations, the number (e.g., quantity) of slots for a subframe may depend on a numerology. For a normal cyclic prefix, a slot may include 14 symbols. For an extended cyclic prefix (e.g., applicable for 60 kHz subcarrier spacing) , a slot may include 12 symbols. The relationship between the number of symbols per slot, the number of slots per subframe, and the number of slots per frame for a normal cyclic prefix and an extended cyclic prefix may depend on a numerology. It should be understood that reference to a first numerology (e.g., μ=0) associated with a first subcarrier spacing (e.g., 15 kHz) may be used interchangeably between subframes and slots.

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.

In the context of the present disclosure, the term “proximity communication 5 (PC5) link” may be used interchangeably with PC5 interface, PC5 connection, PC5 unicast link, PC5-RRC connection, sidelink (SL) , SL unicast link, device-to-device (D2D) link, user-to-user link, UE-to-UE (U2U) link, or the like. The term “relay UE” may be used interchangeably with U2N relay UE, U2U relay UE, layer 2 (L2) relay UE, L2 U2N relay UE, L2 U2U relay UE, or the like. The term “relay UE ID” may be used interchangeably with link ID, path ID, L2 relay UE ID, hop ID, or the like.

A wireless communications system may include one or more devices, such as one or more base stations and/or one or more UEs. In some implementations, two different UEs may communicate with each other via a PC5 link, two different base stations may communicate with each other via an Xn link (or be called as an Xn interface) , and a UE and a base station may communicate with each via a Uu link (or be called as a Uu interface) .

Sidelink communication supports UE-to-UE direct communication using two transmission modes. Two sidelink resource allocation modes are supported, 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 the resource pool based on the measurement result and sensing result.

Sidelink communication includes NR Sidelink communication and V2X Sidelink communication. FIG. 2A illustrates a schematic diagram of an example communication network 210 in which some embodiments of the present disclosure can be implemented. Specifically, the communication network 210 demonstrates the NR Sidelink communication. The NG-RAN architecture supports the PC5 interface as illustrated in FIG. 2A. Sidelink transmission and reception over the PC5 interface are supported when the UE is inside NG-RAN coverage and when the UE is outside NG-RAN coverage.

As shown in FIG. 2A, a UE 211 may communicate with a base station via a relay UE. The base station may be a gNB 212 or an NG-eNB 213, and the relay UE may be a relay UE 214 or a relay UE 215. For example, the NG-eNB 213 may be an evolved long term evolution (eLTE) base station that supports an NG interface. In some embodiments, the sidelink transmission and reception over the PC5 link are supported when the UE 211 is inside Next Generation Radio Access Network (NG-RAN) coverage, irrespective of which RRC state the UE is in, and also supported when the UE 211 is outside NG-RAN coverage.

Support of V2X services via the PC5 interface can be provided by NR sidelink communication and/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.

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 Evolved Universal Terrestrial Radio Access (EUTRA) -based technology, and thus cannot be applied to NR-based system, for both NG-RAN and NR-based sidelink communication.

Sidelink relay is introduced to support 5G ProSe UE-to-Network (U2N) Relay function to provide connectivity to the network for U2N Remote UE. A U2N Relay UE shall be in RRC_CONNECTED to perform relaying of unicast data. In path switching case, a U2N Relay UE in RRC_IDLE, RRC_INACTIVE or RRC_CONNECTED can be selected as target relay UE. For L2 U2N Relay operation, the following RRC state combinations are supported:

- Both L2 U2N Relay UE and L2 U2N Remote UE shall be in RRC_CONNECTED to perform transmission/reception of relayed unicast data; and

- The L2 U2N Relay UE can be in RRC_IDLE, RRC_INACTIVE or RRC_CONNECTED as long as all the L2 U2N Remote UE (s) that are connected to the L2 U2N Relay UE are either in RRC_INACTIVE or in RRC_IDLE.

FIG. 2B illustrates a schematic diagram of an example communication network 220 of a U2N relay. The communication network 220 includes a remote UE 221 and a gNB 222 which are communicated via a relay UE 223. The remote UE 221, which is an out-of-coverage UE, accesses the gNB 222 via the relay UE 223. There are RRC connection between the remote UE 221 and the gNB 222. For example, the remote UE 221 has the RRC state, such as an RRC_idle state, an RRC_inactive state, or an RRC_connected state.

A single unicast link is established between one L2 U2N Relay UE (e.g., the relay UE 223) and one L2 U2N Remote UE (e.g., the remote UE 221) . The traffic of L2 U2N Remote UE via a given L2 U2N Relay UE and the traffic of the L2 U2N Relay UE shall be separated in different Uu Relay RLC channels. For L2 U2N Relay, the U2N Remote UE can only be configured to use resource allocation mode 2 for data to be relayed.

A procedure of RemoteUEInformationSidelink message is used by the L2 U2N Remote UE in RRC_IDLE/RRC_INACTIVE to inform about the required SIB (s) /posSIB (s) , provide Paging related information to the connected L2 U2N Relay UE, request the SFN-DFN offset from the connected L2 U2N Relay UE, and trigger L2 U2N Relay UE in RRC_IDLE/RRC_INACTIVE to enter RRC_CONNECTED during indirect path addition/change in MP operation. This procedure is also used by the L2 U2U Remote UE to send end-to-end PC5 connection release/failure related information to L2 U2U Relay UE. This procedure is used by the L2 U2N Remote UE in RRC_CONNECTED to request the SFN-DFN offset from the connected L2 U2N Relay UE.

The in-coverage L2 U2N Remote UE is allowed to acquire any necessary SIB (s) over Uu interface irrespective of its PC5 connection to L2 U2N Relay UE. The L2 U2N Remote UE can also receive the system information from the L2 U2N Relay UE after PC5 connection establishment with L2 U2N Relay UE.

The L2 U2N Remote UE in RRC_CONNECTED can use the on-demand SIB framework to request the SIB (s) via L2 U2N Relay UE. The L2 U2N Remote UE in RRC_IDLE or RRC_INACTIVE can inform L2 U2N Relay UE of its requested SIB type (s) via PC5-RRC message. Then, L2 U2N Relay UE triggers on-demand SI/SIB acquisition procedure according to its own RRC state (if needed) and sends the acquired SI (s) /SIB (s) to L2 U2N Remote UE via PC5-RRC message.

Any SIB that the RRC_IDLE or RRC_INACTIVE L2 U2N Remote UE has a requirement to use (e.g., for relay purpose) can be requested by the L2 U2N Remote UE (from the L2 U2N Relay UE or the network) . For SIBs that have been requested by the L2 U2N Remote UE from the L2 U2N Relay UE, the L2 U2N Relay UE forwards them again in case of any update for requested SIB (s) . In case of RRC_CONNECTED L2 U2N Remote UE (s) , it is the responsibility of the network to send updated SIB (s) to L2 U2N Remote UE (s) when they are updated. The L2 U2N Remote UE de-configures SI request with L2 U2N Relay UE when entering into RRC_CONNECTED state.

For SIB1 forwarding, for L2 U2N Remote UE, both request-based delivery (i.e., SIB1 request by the U2N Remote UE) and unsolicited forwarding are supported by L2 U2N Relay UE, of which the usage is left to L2 U2N Relay UE implementation. If SIB1 changes, for L2 U2N Remote UE in RRC_IDLE or RRC_INACTIVE, the L2 U2N Relay UE always forwards SIB1.

For the L2 U2N Remote UE in RRC_IDLE or RRC_INACTIVE, the short message over Uu interface is not forwarded by the L2 U2N Relay UE to the L2 U2N Remote UE. The L2 U2N Relay UE can forward PWS SIBs to its connected L2 U2N Remote UE (s) .

RAN sharing is supported for L2 U2N Relay UE. In particular, the L2 U2N Relay UE may forward, via discovery message, cell access related information before the establishment of a PC5-RRC connection.

In some cases, two or more than two relay UEs are needed for a communication of the U2N remote UE. FIG. 2C illustrates a schematic diagram of an example communication network 200 in which some embodiments of the present disclosure can be implemented. As shown in FIG. 2C, a remote UE 230-1 is connected to the base station 235 via a relay UE 231-1 and a relay UE 232-3. As shown in FIG. 2C, a remote UE 230-2 is connected to the base station 235 via a relay UE 231-2, a relay UE 232-2, and the relay UE 232-3.

As shown in FIG. 2C, the relay UE 232-2 and the relay UE 232-3 are located in coverage of the base station 235, while the remote UE 230-1, the remote UE 230-2, the relay UE 231-1, and the relay UE 231-2 are out of the coverage of the base station 235.

For ease of description, the remote UE 230-1 and the remote UE 230-2 can be collectively or separately referred to as a remote UE 230. As illustrated, the remote UE 230 accesses the base station 235 via two or more relay UEs, i.e., via multiple relay UEs or multi-hop. For example, a number of the multiple relay UEs is larger than or equals to 2.

For ease of description, the relay UE 231-1 and the relay UE 231-2 can be collectively or separately referred to as a first relay UE 231. The first relay UE 231 has a PC5 connection with the remote UE 230, that is, the first relay UE 231 may be regarded one of the multiple relay UEs that is closest to the remote UE 230. In some examples, the first relay UE 231 may also be called as the first hop relay UE, the first hop UE, or the like, the present disclosure does not limit for this aspect.

In some examples, a relay UE in the multiple relay UEs which is closest to the base station 235 may be called as a last relay UE, a last hop relay UE, a last hop UE, such as the relay UE 232-3 in FIG. 2C. The last relay UE 232-3 has a Uu connection (i.e., a direct path) with the base station 235.

In some examples, the relay UE 232-2 can be referred to as an intermediate relay UE. In some other examples, the relay UE 232-2 and the relay UE 232-3 can be collectively or separately referred to as an intermediate relay UE.

In some examples, the remote UE 230 accesses the base station 235 via multiple relay UEs (such as N relay UEs, N is an integer and N≥2) which may include a first relay UE, a second relay UE, …, and a N-th relay UE. For example, there are the first relay UE to the (i-1) -th relay UE between the remote UE and the i-the relay UE, and there are the (i+1) -th relay UE to the N-th relay UE between the i-th relay UE and the base station. With reference to FIG. 2C, for the remote UE 230-1, the relay UE 231-1 is a first relay UE and the relay UE 232-3 is a second relay UE. For the remote UE 230-2, the relay UE 231-2 is the first relay UE, the relay UE 232-2 is a second relay UE, and the relay UE 232-3 is a third relay UE.

In the present disclosure, terms “child relay UE” and “parent relay UE” may be used. In some examples, among the multiple relay UEs between a remote UE and a base station, a child relay UE is closer to the remote UE than the parent relay UE, in other words, a parent relay UE is closer to the base station than the child relay UE.

With reference to FIG. 2C, the first relay UE 231-2 is a child relay UE of the second relay UE 232-2, and the second relay UE 232-2 is a parent relay UE of the first relay UE 231-2. The relay UE 232-3 is a parent relay UE of both the relay UE 232-2 and the relay UE 231-1, that is, the relay UE 232-2 and the relay UE 231-1 are child relay UEs of the relay UE 232-3.

It is to be noted that a relay UE can act as both the “child relay UE” and “parent relay UE” , for example, the relay UE 232-2 is a parent relay UE of the relay UE 231-2 and is also a child relay UE of the relay UE 232-3.

In the present disclosure, a term “serve” may be used for representing a relation of two different UEs. In some examples, a UE is served by another UE which is closer to the base station. With reference to FIG. 2C, the remote UE 230-2 is served by the first relay UE 231-2, the first relay UE 231-2 is served by the relay UE 232-2, and the relay UE 232-2 is served by the relay UE 232-3. Similarly, the remote UE 230-1 is served by the first relay UE 231-1, which is served by the relay UE 232-3. It is to be understood that there may be one or multiple remote UEs served by a same relay UE, and there may be one or multiple relay UEs served by a same parent relay UE.

In the present disclosure, “SIB acquisition” is used, which may also be referred to as SI acquisition and the present disclosure does not limit for this aspect.

It is to be understood that the number of devices in FIG. 2C is given for the purpose of illustration without suggesting any limitations to the present disclosure. For example, there may be more relay UEs between the remote UE 230 and the base station 235. For example, there may be another remote UE served by the first relay UE 231-1 or 231-2. For example, the relay UE 232-2 may be out of the coverage. For example, the relay UE 231-1 may be in the coverage.

In the scenario that there are two or more than two relay UEs between a remote UE 230 and a base station 235, how to enable the SIB acquisition for the remote UE 230 should be addressed.

FIG. 3 illustrates a signalling chart illustrating communication process 300 in accordance with some example embodiments of the present disclosure. The process 300 may involve the remote UE 230-1, the first relay UE 231-1, the second relay UE 232-3, and the base station 235 as shown in FIG. 2C. It is to be understood that the process 300 may also be applied to another scenario different from that shown in FIG. 2C, the present disclosure does not limit this aspect.

For ease of description, the process 300 assumes that there are two relay UEs between a remote UE and a base station. The remote UE 230-1 accesses the base station 235 via multiple relay UEs including the first relay UE 231-1 and the second relay UE 232-3. The second relay UE 232-3 has a direct connection or a direct path towards (or with) the base station 235, that is, the second relay UE 232-3 is closest to the base station 235 in the multi-hop link. The first relay UE 231-1 accesses the base station 235 via the second relay UE 232-3. In some examples, when the remote UE 230-1 is in an RRC connected (RRC_CONNECTED) state, an end-to-end connection between the remote UE 230-1 and the base station 235 is established. For example, a multi-hop U2N relay communication is enabled.

At 310, the remote UE 230-1 is configured into an idle or inactive state. In some examples, the base station 235 may configure the remote UE 230-1 into RRC_IDLE or RRC_INACTIVE state. In some examples, the first relay UE 231-1 can be configured into an RRC idle or RRC inactive state, e.g., if all UEs served by the first relay UE 231-1 are in idle state or inactive state.

At 320, the remote UE 230-1 transmits a first request to the first relay UE 231-1, the first request may be used for requesting a first SIB list of the remote UE 230-1. In some examples, the first request may be included in a PC5-RRC message, such as RemoteUEInformationSidelink, which may include requested first SIB list (e.g., sl-RequestedSIB-List) .

After receiving the first request from the remote UE 230-1, the first relay UE 231-1 may decide to perform option 1 (including operation 330) or option 2 (including operation 342) . In some implementations, if a condition for SIB acquisition is met, the first relay UE 231-1 may perform the SIB acquisition procedure at 330; otherwise, the first relay UE 231-1 may transmit a second request to its parent relay UE (i.e., the second relay UE 232-3) at 342. In some examples, the second request may be used for requesting a second SIB list related to the remote UE 230-1 and the first relay UE 231-1.

In some examples, if the first relay UE 231-1 is in coverage of the base station 235, e.g., the first relay UE 231-1 is in an idle or inactive (RRC_IDLE, or RRC_INACTIVE) state, the SIB acquisition procedure may be performed at 330. In some examples, if the first relay UE 231-1 is in a connected (RRC_CONNECTED) state, the SIB acquisition procedure may be performed at 330.

In some examples, if the first relay UE 231-1 is configured as a UE responsible for SIB acquisition, the SIB acquisition procedure may be performed at 330. For example, as illustrated in FIG. 3, the base station 235 may transmit a configuration to the first relay UE 231-1 at 302. For example, whether the first relay UE 231-1 (e.g., in an idle or inactive state) can perform the SIB acquisition procedure via Uu interface is configurable. In some examples, if the first relay UE 231-1 is connected, the configuration may indicate that the first relay UE 231-1 is the UE responsible for SIB acquisition, that is, the first relay UE 231-1 is responsible for SIB acquisition. In some instances, the configuration may be transmitted via dedicated signalling. In some instances, the configuration is transmitted from the base station 235 via the second relay UE 232-3 (i.e., a parent relay UE of the first relay UE 231-1) . Alternatively, the configuration, which indicates that the first relay UE 231-1 is responsible for SIB acquisition, may also be transmitted to the remote UE 230-1 and/or the second relay UE 232-3.

In some examples, if the first relay UE 231-1 determines that a condition configured by the base station 235 is met, the SIB acquisition procedure may be performed at 330. For example, a threshold is configured. For example, as illustrated in FIG. 3, the base station 235 may transmit a configuration to the first relay UE 231-1 at 302. In some examples, the configuration may include the condition or include the threshold. For example, the condition may be a channel quality of the first relay UE 231-1 is larger than or equals to the threshold, the first relay UE 231-1 may determine whether the condition is met, and further determines to perform SIB acquisition procedure if the condition is met.

In some examples, the first relay UE 231-1 may obtain a SIB list based on the SIB acquisition procedure, for example, the obtained SIB list may be the same as the first SIB list, or may be a part of the first SIB list, or may include the first SIB list.

As illustrated, in option 2, at 342, the first relay UE 231-1 may transmit a second request, which may request SIB list for both the remote UE 230-2 and the first relay UE 231-1. In some examples, the second request may be included in a PC5 message, a name of which is not limited in the present disclosure, for example, the PC5 message may be a new-defined message ChildRelayUEInformationSidelink.

In some examples, if the first relay UE 231-1 is out of the coverage of the base station 235, the first relay UE 231-1 may transmit the second request. In some examples, if the first relay UE 231-1 is out of the coverage of the base station 235 and the first relay UE 231-1 is in an idle or inactive state, the first relay UE 231-1 may transmit the second request.

In some examples, if the first relay UE 231-1 is not configured as the UE responsible for SIB acquisition, the first relay UE 231-1 may transmit the second request. For example, the configuration at 302 may indicate that the second relay UE 232-3 is responsible for SIB acquisition. In some instances, the configuration 302 may indicate that a relay UE closest to the base station 235 or a relay UE that has a direct connection towards the base station 235 or the last relay UE is responsible for SIB acquisition. For instance, after receiving the first request and according to the configuration, if the first relay UE 231-1 has not stored a valid version of SIB and the requested first SIB list has not been indicated in a PC5 RRC message from the second relay UE 232-3 before, the first relay UE 231-1 may determine to transmit the second message.

In some examples, if the first relay UE 231-1 determines that the condition configured by the base station 235 is not met, the first relay UE 231-1 may transmit the second request, for example, the condition may be related to a threshold which is discussed above.

In some examples, the second request may include requested SIB list for both the remote UE 230-1 and the first relay UE 231-1. In some examples, there may be other UE (s) served by the first relay UE 231-1, and other SIB list request (s) may be received from other UE (s) , in this case, the second request may request SIB list related to the remote UE 230-1, the first relay UE 231-1, and other UE (s) .

At 344, the second relay UE 232-3 performs the SIB acquisition procedure based on the second request, for example, a third SIB list may be obtained. In some examples, the obtained third SIB list may be the same as the requested second SIB list, or may be a part of the second SIB list, or may include the second SIB list. For example, the third SIB list may be a subset of the second SIB list.

In some examples, the second relay UE 232-3 may perform SIB acquisition directly if it is in the coverage of the base station 235, e.g., the second relay UE 232-3 is in RRC_IDLE or RRC_INACTIVE. In some examples, the second relay UE 232-3 may perform SIB acquisition directly if it is in RRC_CONNECTED.

In some examples, the second relay UE 232-3 may trigger an on-demand SI/SIB acquisition procedure according to its own RRC state (if needed) . For example, the second relay UE 232-3, e.g., in RRC_IDLE or RRC_INACTIVE, may perform SI acquisition. For example, the second relay UE 232-3, e.g., in RRC_CONNECTED, may transmit a request to the base station 235 for SIB request.

At 346, the second relay UE 232-3 transmits the third SIB list to the first relay UE 231-1. In some examples, the third SIB list may include acquired SI (s) or SIB (s) . In some examples, the third SIB list may be transmitted via a PC5-RRC message, such as UuMessageTransferSidelink message.

At 350, the first relay UE 231-1 transmits, e.g., a fourth SIB list, to the remote UE 230-1. In some examples, the fourth SIB list may be determined based on the SIB list obtained at 330 or based on the third SIB list received at 346. In some examples, the fourth SIB list may be a part of the SIB list obtained at 330 or a part of the third SIB list received at 346.

In some examples, the fourth SIB list may be the same as the first SIB list, or may be a part of the first SIB list. In some examples, the fourth SIB list may be transmitted via a PC5 message at 350, for example, the PC5 message may be a new-defined message or may be an existing message, such as UuMessageTransferSidelink message.

In some examples, the first relay UE 231-1 may initiate a Uu message transfer procedure based one or more of: receiving the first SIB list of the remote UE, receiving an update of the first SIB list, receiving an unsolicited SIB1 from the second relay UE 232-3, or receiving an updated SIB1. For example, the first relay UE 231-1 initiates the Uu message transfer procedure upon acquisition of the SIB (s) requested by the remote UE 230-1 or upon receiving the updated SIB (s) from base station 235. For example, the first relay UE 231-1 initiates the Uu message transfer procedure upon receiving an unsolicited SIB1 (e.g., and forwarding the unsolicited SIB1 to the connected remote UE 230-1) or upon receiving the updated SIB1 from base station 235 e.g. via the second relay UE 232-3.

According to embodiments with reference to FIG. 3, in case the remote UE 230-1 is in an idle or inactive state and there are multiple relay UEs between the remote UE 230-1 and the base station 235, a procedure is defined for obtaining the SIB list of the remote UE 230-1. For example, a UE responsible for SIB acquisition may be configured in some cases. As such, an accurate communication for the remote UE can be guaranteed.

It is to be appreciated that although option 1 and option 2 are described independently in FIG. 3, in some other examples, both option 1 and option 2 are performed. In some instances, although the first relay UE 231-1 can perform SIB acquisition, the first relay UE 231-1 is also allowed to transmit the second request to the second relay UE 232-3. For instance, the first relay UE 231-1 may obtain a SIB list based on the SIB acquisition procedure, and also receives a third SIB list from the second relay UE 232-3. For instance, the first relay UE 231-1 may determine the fourth SIB list (which is to be transmitted to the remote UE 230-1 at 350) based on both the SIB list obtained at 330 and the third SIB list received at 346. In this case, there will be multiple relay UEs performing SIB acquisition for the remote UE 230-1.

In some implementations, as mentioned above, the first relay UE 231-1 may perform SIB acquisition procedure at 330, however, a condition of the first relay UE 231-1 may change and an update of the SIB acquisition may be needed. In some examples, if one or more of the following conditions are met, the first relay UE 231-1 may trigger a transmission of the second request to the second relay UE 232-3: the first relay UE 231-1 moves from in coverage (IC) of the base station 235 to out of the coverage (OOC) , or the first relay UE 231-1 moves to an idle or inactive state and out of the coverage, or the first relay UE 231-1 in the coverage transits from a connected state to an idle or inactive state, or the first relay UE 231-1 transits from the connected state to an idle or inactive state out of the coverage. For example, if the first relay UE 231-1 moves from IC to OOC, or transits from RRC_CONNECTED to RRC_IDEL/RRC_INACTIVE (in coverage) , or transits from RRC_CONNECTED to RRC_IDEL/RRC_INACTIVE (out of coverage) , the second request (i.e., a PC5 RRC message such as ChildUEInformationSidelink) can be triggered. As such, a trigger condition is defined to transmit or update the requested SIB list from the first relay UE 231-1 to its parent relay UE (i.e. the second relay UE 232-3) via a PC5 RRC message e.g., ChildUEInformationSidelink.

In some implementations, as mentioned above, the first relay UE 231-1 may transmit a second request to the second relay UE 232-3 at 342, however, a condition of the first relay UE 231-1 may change and an update of the SIB acquisition may be needed. In some examples, if one or more of the following conditions are met, the first relay UE 231-1 may transmit a message for stopping acquiring the second SIB list to the second relay UE 232-3: the first relay UE 231-1 moves from out of coverage of the base station to in coverage, or the first relay UE 231-1in the coverage transits from an idle or inactive state to a connected state, or the first relay UE 231-1 transits from an idle or inactive state out of the coverage to the connected state in coverage. For example, the message may include a value for requesting SIB which is set as release.

In some instances, when one of the following conditions (a1) - (a3) is met, the first relay UE 231-1 may perform actions: if the first relay UE 231-1 has sent sl-RequestedSIB-List and/or sl-RequestedPosSIB-Lis, the first relay UE 231-1 may set the sl-RequestedSIB-List to a value “release” if requested before. For instance, the first relay UE 231-1 may provide a RemoteUEInformationSidelink message to a lower layer for transmission. For instance, the conditions (a1) - (a3) may include: (a1) the first relay UE 231-1 is in RRC_IDLE or RRC_INACTIVE, and it moves from OOC to IC; (a2) the first relay UE 231-1 transits from RRC_IDLE or RRC_INACTIVE to RRC_CONNECTED; (a3) the first relay UE 231-1 transits from OOC&RRC_IDLE (or RRC_INACTIVE) to RRC_CONNECTED.

It should be noted that although embodiments with reference to FIG. 3 are provided with two relay UEs between the remote UE 230-1 and the base station 235, the present disclosure is also applied for a scenario with more than two relay UEs. FIG. 4 illustrates a signalling chart illustrating communication process 400 related to a remote UE 230-2 in FIG. 2C. The process 400 involves the remote UE 230-2, the first relay UE 231-2, the second relay UE 232-2, the third relay UE 232-3, and the base station 235. It is to be understood that the process 400 may also be applied to another scenario different from that shown in FIG. 2C, the present disclosure does not limit this aspect. In some examples, more relay UEs are also applied, for example, there may be other relay UE (s) between the first relay UE 231-2 and the second relay UE 232-2, or between the second relay UE 232-2 and the third relay UE 232-3, and each of other relay UE (s) may have similar operations with the second relay UE 232-2.

The remote UE 230-2 accesses the base station 235 via multiple relay UEs including the first relay UE 231-2, the second relay UE 232-2, and the third relay UE 232-3. The third relay UE 232-3 has a direct connection or a direct path towards (or with) the base station 235, that is, the third relay UE 232-3 is closest to the base station 235 in the multi-hop link. The first relay UE 231-2 accesses the base station 235 via the relay UE 232-2 and the relay UE 232-3. In some examples, when the remote UE 230-2 is in an RRC connected (RRC_CONNECTED) state, an end-to-end connection between the remote UE 230-2 and the base station 235 is established. For example, a U2N relay communication is enabled.

At 410, the remote UE 230-2 is configured into an idle or inactive state. In some examples, the base station 235 may configure the remote UE 230-2 into RRC_IDLE or RRC_INACTIVE state. In some examples, the first relay UE 231-2 can be configured into an idle or inactive state, e.g., if all UEs served by the first relay UE 231-2 are in idle/inactive state. In some examples, the second relay UE 232-2 can be configured into an idle or inactive state, e.g., if all UEs (including the remote UE 230-2 and the first relay UE 231-2) served by the second relay UE 232-2 are in idle/inactive state.

At 420, the remote UE 230-2 transmits a first request to the first relay UE 231-2, the first request may be used for requesting a first SIB list of the remote UE 230-2. Details of the operation 420 may refer to those with reference to operation 320 in FIG. 3, and thus will not be repeated herein. In addition, the operation (s) 430 or 440 or 450 may be performed.

After receiving the first request from the remote UE 230-2, in some cases the first relay UE 231-2 may perform SIB acquisition procedure at 430. Details of the operation 430 may refer to the operation 330 in FIG. 3, and thus will not be repeated herein. For example, a SIB list, such as the first SIB list can be obtained, and in addition, the first relay UE 231-2 transmits the obtained SIB list to the remote UE 230-2 at 460. For instance, the operations in blocks 440 and 450 may not be performed.

After receiving the first request from the remote UE 230-2, in some cases the first relay UE 231-2 may transmit a second request to its parent relay UE (i.e., the second relay UE 232-2) at 442. For example, the second request may include requested SIB list related to the remote UE 230-2 and the first relay UE 231-2, and optionally may further related to other child UE (s) of the first relay UE 231-2. Details of the operation 442 may refer to the operation 342 in FIG. 3, and thus will not be repeated herein.

As illustrated, after receiving the second request from its child relay UE (i.e. the first relay UE 231-2) , the second relay UE 232-2 may perform SIB acquisition procedure at 444 or may transmit a third request to its parent relay UE (i.e. the third relay UE 232-3) at 452.

In some examples, the second relay UE 232-2 may determine to perform SIB acquisition procedure at 444 in a similar manner with the operation 430. For example, a SIB list may be obtained based on the SIB acquisition procedure at 444. For example, if the second relay UE 232-2 is in coverage of the base station 235, the SIB acquisition procedure may be performed at 444. For example, if the second relay UE 232-2 is in RRC_CONNECTED, the SIB acquisition procedure may be performed at 444. For example, if the second relay UE 232-2 is configured as a UE responsible for SIB acquisition, the SIB acquisition procedure may be performed at 444, for instance, the configuration at 402 may be transmitted to at least the second relay UE 232-2 and the configuration may configure the second relay UE 232-2 to perform the SIB acquisition for the remote UE 230- 2. For example, if a condition configured by the base station 235 is met, the SIB acquisition procedure may be performed at 444, for instance, the condition is associated with a threshold which is included in the configuration at 402. For instance, the configured condition is that a channel quality of the second relay UE 232-2 is larger than or equals to the threshold.

For example, a SIB list, such as a second SIB list can be obtained by 444, and in addition, the second relay UE 232-2 transmits the obtained SIB list to the first relay UE 231-2 at 446. Further, the first relay UE 231-2 transmits the SIB list related to the remote UE 230-2 (which is determined based on the SIB list received form the second relay UE 232-2) to the remote UE 230-2 at 460. For instance, the operations in blocks 450 may not be performed.

In some examples, the second relay UE 232-2 may determine to transmit a third request to its parent relay UE, (i.e., the third relay UE 232-3) at 452 in a similar manner with the operation 442. For example, if the second relay UE 232-2 is out of the coverage of the base station 235, the second relay UE 232-2 may transmit the third request at 452. For example, if the second relay UE 232-2 is out of the coverage of the base station 235 and is in an idle or inactive state, the second relay UE 232-2 may transmit the third request at 452. For example, if the second relay UE 232-2 is not configured as the UE responsible for SIB acquisition, the second relay UE 232-2 may transmit the third request at 452. For example, if a condition associated with a threshold configured by the base station 235 is not met, the second relay UE 232-2 may transmit the third request at 452.

After receiving the third request, the third relay UE 232-2 performs the SIB acquisition procedure at 454 based on the third request. It is noted that details of the operation 454 in FIG. 4 can refer to those discussed with reference to operation 344 in FIG. 3, thus will not be repeated herein.

For example, a SIB list, such as a third SIB list can be obtained by 454, and in addition, the third relay UE 232-3 transmits the obtained SIB list to the second relay UE 232-2 at 456.

The second relay UE 232-2 may determine a SIB list from the received SIB list, e.g., based on the second request, for example, a fourth SIB list may be determined. In addition, the second relay UE 232-2 transmits the determined SIB list to the first relay UE 231-2 at 458. Further, the first relay UE 231-2 transmits the SIB list related to the remote UE 230-2 (which is determined based on the SIB list received form the second relay UE 232-2) to the remote UE 230-2 at 460.

In some examples, the SIB list transmitted at 460 may be the same as the first SIB list, or may be a part of the first SIB list. In some examples, the SIB list at 460 may be transmitted via a PC5 message, for example, the PC5 message may be a new-defined message or may be an existing message, such as UuMessageTransferSidelink message.

In some examples, the first relay UE 231-2 may initiate a Uu message transfer procedure based one or more of: receiving the first SIB list of the remote UE, receiving an update of the first SIB list, receiving an unsolicited SIB1 from the second relay UE 232-2, or receiving an updated SIB1.

According to embodiments with reference to FIG. 4, in case the remote UE 230-2 is in an idle or inactive state and there are multiple relay UEs between the remote UE 230-2 and the base station 235, a procedure is defined for obtaining the SIB list of the remote UE 230-2. For example, a UE responsible for SIB acquisition may be configured in some cases. As such, an accurate communication for the remote UE can be guaranteed.

It is to be appreciated that although operations 430, 440, and 450 are described independently in FIG. 4, in some other examples, part or all of the operations 430, 440, and 450 are performed. In some instances, although the first relay UE 231-2 can perform SIB acquisition, the first relay UE 231-2 is also allowed to transmit the second request to the second relay UE 232-2. In some instances, although the second relay UE 232-2 can perform SIB acquisition, the second relay UE 232-2 is also allowed to transmit the third request to the third relay UE 232-3. In this case, there will be multiple relay UEs performing SIB acquisition for the remote UE 230-2.

In some examples, if one or more of the following conditions are met, a child relay UE (such as the first relay UE 231-2 or the second relay UE 232-2) may trigger a transmission of a request to its parent relay UE (such as the second relay UE 232-3 for the first relay UE 231-2, such as the third relay UE 232-3 for the second relay UE 232-2) : the child relay UE moves from IC of the base station 235 to OOC, or the child relay UE moves to an idle or inactive state and OOC, or the child relay UE IC transits from a connected state to an idle or inactive state, or the child relay UE transits from the connected state to an idle or inactive state and OOC. For example, the request to the parent relay UE may be implemented as a PC5 RRC message e.g., ChildUEInformationSidelink.

In some examples, if one or more of the following conditions are met, a child relay UE (such as the first relay UE 231-2 or the second relay UE 232-2) may transmit a message for stopping acquiring a SIB list to its parent relay UE (such as the second relay UE 232-3 for the first relay UE 231-2, such as the third relay UE 232-3 for the second relay UE 232-2) : the child relay UE moves from OOC to IC, or the child relay UE IC transits from an idle or inactive state to a connected state, or the child relay UE transits from an idle or inactive state OCC to the connected state IC. For example, the message may include a value for requesting SIB which is set as release.

It should be noted that although embodiments with reference to FIG. 4 are provided with three relay UEs between the remote UE 230-2 and the base station 235, the present disclosure is also applied for a scenario with more relay UEs. For example, there may be other relay UE (s) between the first relay UE 231-2 and the second relay UE 232-2, or between the second relay UE 232-2 and the third relay UE 232-3, and each of other relay UE (s) may have similar operations with the second relay UE 232-2.

According to embodiments shown in FIGS. 3-4, a solution of SIB acquisition for a remote UE is proposed. In the solution, there may two or more relay UEs between the remote UE and a serving base station, and a procedure is defined for obtaining the SIB list of the remote UE. As such, an accurate communication for the remote UE can be guaranteed.

FIG. 5 illustrates an example of a device 500 that is suitable for implementing embodiments of the present disclosure. The device 500 may be an example of a RAN node as described herein. The device 500 may support wireless communication with the remote UE 230, the relay UE 231 or 232, the BS 235, or any combination thereof. The device 500 may include components for bi-directional communications including components for transmitting and receiving communications, such as a processor 502, a memory 504, a transceiver 506, and, optionally, an I/O controller 508. 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 502, the memory 504, the transceiver 506, 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 502, the memory 504, the transceiver 506, 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 502, the memory 504, the transceiver 506, 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 502 and the memory 504 coupled with the processor 502 may be configured to perform one or more of the functions described herein (e.g., executing, by the processor 502, instructions stored in the memory 504) .

For example, the processor 502 may support wireless communication at the device 500 in accordance with examples as disclosed herein. The processor 502 may be configured to operable to support a means for actions discussed above.

The processor 502 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, 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 502 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 502. The processor 502 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 504) to cause the device 500 to perform various functions of the present disclosure.

The memory 504 may include random access memory (RAM) and read-only memory (ROM) . The memory 504 may store computer-readable, computer-executable code including instructions that, when executed by the processor 502 cause the device 500 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 502 but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some implementations, the memory 504 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 508 may manage input and output signals for the device 500. The I/O controller 508 may also manage peripherals not integrated into the device M02. In some implementations, the I/O controller 508 may represent a physical connection or port to an external peripheral. In some implementations, the I/O controller 508 may utilize an operating system such as or another known operating system. In some implementations, the I/O controller 508 may be implemented as part of a processor, such as the processor 506. In some implementations, a user may interact with the device 500 via the I/O controller 508 or via hardware components controlled by the I/O controller 508.

In some implementations, the device 500 may include a single antenna 510. However, in some other implementations, the device 500 may have more than one antenna 510 (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 506 may communicate bi-directionally, via the one or more antennas 510, wired, or wireless links as described herein. For example, the transceiver 506 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 506 may also include a modem to modulate the packets, to provide the modulated packets to one or more antennas 510 for transmission, and to demodulate packets received from the one or more antennas 510. The transceiver 506 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 510 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 510 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. 6 illustrates an example of a processor 600 that is suitable for implementing some embodiments of the present disclosure. The processor 600 may be an example of a processor configured to perform various operations in accordance with examples as described herein. The processor 600 may include a controller 602 configured to perform various operations in accordance with examples as described herein. The processor 600 may optionally include at least one memory 604, such as L1/L2/L3 cache. Additionally, or alternatively, the processor 600 may optionally include one or more arithmetic-logic units (ALUs) 606. 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 600 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 600) 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 602 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 600 to cause the processor 600 to support various operations in accordance with examples as described herein. For example, the controller 602 may operate as a control unit of the processor 600, generating control signals that manage the operation of various components of the processor 600. These control signals include enabling or disabling functional units, selecting data paths, initiating memory access, and coordinating timing of operations.

The controller 602 may be configured to fetch (e.g., obtain, retrieve, receive) instructions from the memory 604 and determine subsequent instruction (s) to be executed to cause the processor 600 to support various operations in accordance with examples as described herein. The controller 602 may be configured to track memory address of instructions associated with the memory 604. The controller 602 may be configured to decode instructions to determine the operation to be performed and the operands involved. For example, the controller 602 may be configured to interpret the instruction and determine control signals to be output to other components of the processor 600 to cause the processor 600 to support various operations in accordance with examples as described herein. Additionally, or alternatively, the controller 602 may be configured to manage flow of data within the processor 600. The controller 602 may be configured to control transfer of data between registers, arithmetic logic units (ALUs) , and other functional units of the processor 600.

The memory 604 may include one or more caches (e.g., memory local to or included in the processor 600 or other memory, such RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc. In some implementations, the memory 604 may reside within or on a processor chipset (e.g., local to the processor 600) . In some other implementations, the memory 604 may reside external to the processor chipset (e.g., remote to the processor 600) .

The memory 604 may store computer-readable, computer-executable code including instructions that, when executed by the processor 600, cause the processor 600 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 602 and/or the processor 600 may be configured to execute computer-readable instructions stored in the memory 604 to cause the processor 600 to perform various functions. For example, the processor 600 and/or the controller 602 may be coupled with or to the memory 604, the processor 600, the controller 602, and the memory 604 may be configured to perform various functions described herein. In some examples, the processor 600 may include multiple processors and the memory 604 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 606 may be configured to support various operations in accordance with examples as described herein. In some implementations, the one or more ALUs 606 may reside within or on a processor chipset (e.g., the processor 600) . In some other implementations, the one or more ALUs 606 may reside external to the processor chipset (e.g., the processor 600) . One or more ALUs 606 may perform one or more computations such as addition, subtraction, multiplication, and division on data. For example, one or more ALUs 606 may receive input operands and an operation code, which determines an operation to be executed. One or more ALUs 606 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 606 may support logical operations such as AND, OR, exclusive-OR (XOR) , not-OR (NOR) , and not-AND (NAND) , enabling the one or more ALUs 606 to handle conditional operations, comparisons, and bitwise operations.

The processor 600 may support wireless communication in accordance with examples as disclosed herein. The processor 600 may be configured to or operable to support a means for operations described in some embodiments of the present disclosure.

FIG. 7 illustrates a flowchart of a method 700 performed by a first UE in accordance with aspects of the present disclosure. The operations of the method 700 may be implemented by a device or its components as described herein. For example, the operations of the method 700 may be performed by the first relay UE 231 in FIG. 2C. 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 710, the method may include receiving, from a remote UE in an idle or inactive state, a first request for a first SIB list of the remote UE, wherein the remote UE accesses a base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and a second UE. The operations of 710 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 710 may be performed by the first relay UE 231 as described with reference to FIG. 2C. In some examples, the first UE may be a child relay UE and the second UE may be a parent relay UE. For example, there may be a PC5 connection between the remote UE and the first UE. For example, there may be a PC5 connection between the first UE and the second UE. For example, the second UE accesses the base station via a direct path or via at least a third UE.

At 720, the method may include transmitting, to the second UE, a second request for a second SIB list of the remote UE and the first UE. The operations of 720 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 720 may be performed by the first relay UE 231 as described with reference to FIG. 2C.

At 730, the method may include receiving, from the second UE, a third SIB list based on the second request. The operations of 730 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 730 may be performed by the first relay UE 231 as described with reference to FIG. 2C.

At 740, the method may include transmitting, to the remote UE, a fourth SIB list of the remote UE based on the third SIB list. The operations of 740 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 740 may be performed by the first relay UE 231 as described with reference to FIG. 2C.

FIG. 8 illustrates a flowchart of a method 800 performed by a second UE in accordance with aspects of the present disclosure. The operations of the method 800 may be implemented by a device or its components as described herein. For example, the operations of the method 800 may be performed by the relay UE 232 in FIG. 2C. For example, the relay UE 232 is an intermediate relay UE or a last relay UE between a remote UE and a base station. 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 810, the method may include receiving, from a first UE, a request for a first SIB list related to at least a remote UE and the first UE, wherein the remote UE accesses a base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and the second UE. The operations of 810 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 810 may be performed by the relay UE 232 as described with reference to FIG. 2C. In some examples, the first UE may be a child relay UE and the second UE may be a parent relay UE. For example, there may be a PC5 connection between the first UE and the second UE. For example, there may be a PC5 connection between the remote UE and the first UE, or there may be a further relay UE between the remote UE and the first UE. For example, the second UE accesses the base station via a direct path or via at least a third UE. For example, the second UE may be the second relay UE 232-2, and the first UE may be the first relay UE 231-2 as described with reference to FIG. 2C. For example, the second UE may be the last relay UE 232-3, and the first UE may be the first relay UE 231-1 and/or the second relay UE 232-2.

At 820, the method may include transmitting, to the first UE, a second SIB list based on the request. The operations of 820 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 820 may be performed by the second relay UE 232 as described with reference to FIG. 2C.

FIG. 9 illustrates a flowchart of a method 900 performed by a BS in accordance with aspects of the present disclosure. The operations of the method 900 may be implemented by a device or its components as described herein. For example, the operations of the method 900 may be performed by the BS 235 in FIG. 2C. 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 910, the method may include determining a configuration for a SIB acquisition associated with a remote UE. The operations of 910 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 910 may be performed by the BS 235 as described with reference to FIG. 2C.

At 920, the method may include transmitting, to at least a first UE or a second UE, the configuration indicating a UE responsible for SIB acquisition, wherein the remote UE accesses the base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and the second UE. The operations of 920 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 920 may be performed by the BS 235 as described with reference to FIG. 2C.

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, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, 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.

Claims

A first user equipment (UE) comprising:

at least one memory; and

at least one processor coupled with the at least one memory and configured to cause the first UE to:

receive, from a remote UE in an idle or inactive state, a first request for a first system information block (SIB) list of the remote UE, wherein the remote UE accesses a base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and a second UE;

transmit, to the second UE, a second request for a second SIB list of the remote UE and the first UE;

receive, from the second UE, a third SIB list based on the second request; and

transmit, to the remote UE, a fourth SIB list of the remote UE based on the third SIB list.
The first UE of claim 1, wherein there is a proximity communication 5 (PC5) connection between the remote UE and the first UE, there is a PC5 connection between the first UE and the second UE, and wherein the second UE accesses the base station via a direct path or at least a third UE.
The first UE of claim 1, wherein the second request is transmitted based on one of:

the first UE is out of coverage of the base station,

the first UE is out of coverage of the base station, wherein the first UE is idle or inactive state,

the first UE is not configured as a UE responsible for SIB acquisition, or

the first UE is not meeting a condition of SIB acquisition, wherein the condition is configured by the base station.
The first UE of claim 1, wherein the at least one processor is further configured to cause the first UE to:

receive, from the base station, a configuration indicating that one of the first UE, the second UE, or a third UE is a UE responsible for SIB acquisition.
The first UE of claim 1, wherein the at least one processor is further configured to cause the first UE to:

perform an on-demand SIB acquisition procedure to obtain the first SIB list based on one of:

the first UE is in coverage of the base station,

the first UE is in a connected state,

the first UE is configured as a UE responsible for SIB acquisition, or

the first UE is meeting a condition of SIB acquisition, wherein the condition is configured by the base station.
The first UE of claim 1, wherein the at least one processor is further configured to cause the first UE to:

in accordance with one of the following conditions is met, trigger a transmission of the second request:

the first UE moves to an idle or inactive state and out of the coverage,

the first UE moves from in coverage of the base station to out of the coverage,

the first UE in the coverage transits from a connected state to an idle or inactive state, or

the first UE transits from the connected state to an idle or inactive state out of the coverage.
The first UE of claim 1, wherein the at least one processor is further configured to cause the first UE to:

in accordance with one of the following conditions is met, transmit, to the second UE, a message for stopping acquiring the second SIB list:

the first UE moves from out of coverage of the base station to in coverage,

the first UE in the coverage transits from an idle or inactive state to a connected state, or

the first UE transits from an idle or inactive state out of the coverage to the connected state in coverage.
The first UE of claim 7, wherein the message comprises a value for requesting SIB which is set as release.
The first UE of claim 1, wherein the at least one processor is further configured to cause the first UE to:

initiate a Uu message transfer procedure based one of:

receiving the first SIB list of the remote UE,

receiving an update of the first SIB list,

receiving an unsolicited SIB1 from the second UE, or

receiving an updated SIB1.
A second user equipment (UE) comprising:

at least one memory; and

at least one processor coupled with the at least one memory and configured to cause the second UE to:

receive, from a first UE, a request for a first system information block (SIB) list related to at least a remote UE and the first UE, wherein the remote UE accesses a base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and the second UE; and

transmit, to the first UE, a second SIB list based on the request.
The second UE of claim 10, wherein the at least one processor is further configured to:

transmit, to a third UE, a further request for a third SIB list related to at least the remote UE, the first UE, and the second UE based on one of:

the second UE is out of coverage of the base station,

the second UE is out of coverage of the base station, wherein the first UE is idle or inactive state,

the second UE is not configured as a UE responsible for SIB acquisition, or

the second UE is not meeting a condition of SIB acquisition which is configured by the base station; and

receive, from the third UE, a fourth SIB list based on the further request,

wherein the multiple UEs comprises the third UE, and wherein there is a PC5 connection between the second UE and the third UE.
The second UE of claim 11, wherein the at least one processor is further configured to cause the second UE to:

in accordance with one of the following conditions is met, trigger a transmission of the further request:

the second UE moves from in coverage of the base station to out of the coverage,

the second UE in the coverage transits from a connected state to an idle or inactive state, or

the second UE transits from the connected state to an idle or inactive state out of the coverage.
The second UE of claim 11, wherein the at least one processor is further configured to cause the second UE to:

in accordance with one of the following conditions is met, transmit, to the third UE, a message for stopping acquiring the third SIB list:

the second UE moves from out of coverage of the base station to in coverage,

the second UE in the coverage transits from an idle or inactive state to a connected state, or

the second UE transits from an idle or inactive state out of the coverage to the connected state in coverage.
The second UE of claim 13, wherein the message comprises a value for requesting SIB which is set as release.
The second UE of claim 10, wherein the at least one processor is further configured to cause the second UE to:

perform an on-demand SIB acquisition procedure to obtain the second SIB list based on one of:

there is a Uu connection between the second UE and the base station,

the second UE is in coverage of the base station,

the second UE is in a connected state,

the second UE is configured as a UE responsible for SIB acquisition, or

the second UE is meeting a condition of SIB acquisition, wherein the condition is configured by the base station.
The second UE of claim 10, wherein the at least one processor is further configured to cause the second UE to:

receive, from the base station, a configuration indicating that one of the first UE, the second UE, or a third UE is UE responsible for SIB acquisition.
The second UE of claim 10, wherein there is a PC5 connection between the remote UE and the first UE, or there is a further UE between the remote UE and the first UE.
A base station comprising:

at least one memory; and

at least one processor coupled with the at least one memory and configured to cause the base station to:

determine a configuration for a system information block (SIB) acquisition associated with a remote user equipment (UE) ; and

transmit, to at least a first UE or a second UE, the configuration indicating a UE responsible for SIB acquisition,

wherein the remote UE accesses the base station via multiple UEs, and wherein the multiple UEs at least comprises the first UE and the second UE.
The base station of claim 18, wherein the multiple UEs further comprises a third UE, and wherein the UE responsible for SIB acquisition comprises one of: the first UE, the second UE, or the third UE.
A processor for wireless communication, comprising:

at least one controller coupled with at least one memory and configured to cause the processor to execute actions that performed by a first user equipment according to any of claims 1-9 or a second user equipment according to any of claims 10-17.