Method executed by user equipment and user equipment

Abstract

The invention provides a method executed by user equipment (UE) and the UE. The method comprises the following steps: receiving an RRC reconfiguration message sent by a network side, the RRC reconfiguration message comprising first indication information used for initiating path switching of which the target is an indirect path, and second indication information used for indicating the remote UE to keep connection with relay UE which is on a source path and is directly connected with the remote UE; and under the condition that the RRC reconfiguration message is received, executing at least one of the following operations: considering that the serving cell of the relay UE is the serving cell of the remote UE; and starting a timer for confirming whether the RRC reconfiguration completion message is successfully sent or not.

Description

Technical Field

[0001] This disclosure relates to the field of wireless communication technology, and more specifically, to methods performed by user equipment and user equipment. Background Technology

[0002] In March 2020, at the RAN#91 plenary meeting, a work project was proposed regarding NR sidelink relaying in version 17 (see non-patent literature: RP-210904).

[0003] A new study item on NR Sidelink Relaying was approved. The latest version of this work item can be found in non-patent literature: RP-212601 reivised WID NR sidelink relay. One of the goals of this work item is to standardize the process of U2N (UE-to-Network) sidelink relay architecture. In a U2N relay architecture, communication between the remote UE and the network is achieved through a relay UE. Such a scenario can be referred to as a single-hop relay-based scenario, where at most one relay UE serves the remote UE.

[0004] In June 2024, at the RAN#104 plenary meeting, a work project on NR Sidelink multi-hop relay for version 19 was proposed (see non-patent literature: RP-241609 NR sidelink multi-hop relay) and approved. The goal of this work project is to standardize multi-hop L2 U2N relays. Unlike single-hop relay-based scenarios, in multi-hop relay-based scenarios, a remote UE can communicate with the network (or base station) through more than one relay UE; that is, at least two relay UEs provide services to the remote UE, enabling communication with the network.

[0005] To ensure service continuity, the problem that needs to be solved is how to switch between multi-hop relay scenarios and single-hop relay scenarios. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a method and a user equipment executed by a user equipment, which can effectively perform the conversion between multi-hop relay scenarios and single-hop relay scenarios.

[0007] According to the present invention, a method performed by a remote user equipment (i.e., a remote UE) is proposed, comprising the following steps: receiving an RRC reconfiguration message sent by the network side, the RRC reconfiguration message including first indication information for initiating a path handover targeting a non-direct path, and second indication information for instructing the remote UE to maintain a connection with a relay UE on the source path that is directly connected to the remote UE; and upon receiving the RRC reconfiguration message, performing at least one of the following operations: considering the serving cell of the relay UE as the serving cell of the remote UE; and starting a timer for confirming whether the RRC reconfiguration completion message has been successfully sent.

[0008] Preferably, if the remote UE successfully sends the RRC reconfiguration complete message, at least one of the following operations is performed:

[0009] - Stop the timer; and

[0010] - Reset the MAC entity used in the source cell.

[0011] Furthermore, according to the present invention, a method executed by a remote user equipment (i.e., a remote UE) is proposed, comprising the following steps: receiving an RRC reconfiguration message sent by the network side, the RRC reconfiguration message including first indication information for initiating a path handover targeting a non-direct path, second indication information for instructing the remote UE to maintain a connection with a relay UE on the source path that is directly connected to the remote UE, and third indication information indicating whether to start a timer for confirming whether the RRC reconfiguration completion message has been successfully sent; and upon receiving the RRC reconfiguration message, performing at least one of the following operations: considering the serving cell of the relay UE as the serving cell of the remote UE; and starting the timer if the third indication information indicates that the timer should be started.

[0012] Preferably, if the third indication indicates that the timer should not be started, then the timer should not be started.

[0013] Preferably, if the remote UE successfully sends the RRC reconfiguration complete message, at least one of the following operations is performed:

[0014] - If the timer is running, then stop the running timer; and

[0015] - Reset the MAC entity used in the source cell.

[0016] Furthermore, according to the present invention, a method is proposed to be performed by a relay UE directly connected to a remote user equipment, i.e., a remote UE, comprising the following steps: receiving an RRC reconfiguration message sent by the network side, wherein the RRC reconfiguration information includes synchronization information; and upon receiving the RRC reconfiguration message, the relay UE initiates the following notification procedure: setting the indication type to relay UE handover in the notification message, and transmitting the notification message to the remote UE.

[0017] Preferably, the notification message further includes indication information indicating whether the relay UE is an intermediate relay or a last relay.

[0018] In addition, according to the present invention, a user equipment is provided, comprising: a processor; and a memory storing instructions, wherein the instructions, when executed by the processor, perform the method described above.

[0019] Invention Effects

[0020] According to the present invention, it is possible to effectively switch between multi-hop relay scenarios and single-hop relay scenarios. Attached Figure Description

[0021] The above and other features of this disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0022] Figure 1 This is a schematic diagram illustrating a single-hop U2N relay.

[0023] Figure 2 This is a schematic diagram illustrating a multi-hop U2N relay.

[0024] Figure 3 This is a schematic diagram illustrating the switch from a non-direct path based on a multi-hop relay to a non-direct path based on a single-hop relay.

[0025] Figure 4 This is a schematic diagram illustrating the switch from a non-direct path based on a single-hop relay to a non-direct path based on a multi-hop relay.

[0026] Figure 5 This is a flowchart illustrating a method performed by the user equipment (UE) according to the present invention.

[0027] Figure 6 This is a flowchart illustrating method two executed by the user equipment (UE) of the present invention.

[0028] Figure 7 This is a flowchart illustrating method three executed by the user equipment (UE) of the present invention.

[0029] Figure 8 This is a simplified structural block diagram of the user equipment (UE) involved in the present invention. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the present invention should not be limited to the specific embodiments described below. Furthermore, for the sake of simplicity, detailed descriptions of well-known technologies not directly related to the present invention have been omitted to prevent confusion in understanding the present invention.

[0031] The following describes some of the terms involved in this invention. For the specific meanings of these terms, please refer to the latest 3GPP standard specifications.

[0032] UE: User Equipment

[0033] NR: New Radio, next-generation wireless technology

[0034] PHY: physical layer

[0035] MAC: Medium Access Control (Multimedia Access Control Layer)

[0036] RLC: Radio Link Control (layer)

[0037] SDAP: Service Data Adaptation Protocol (Layer)

[0038] PDCP: Packet Data Convergence Protocol (Layer)

[0039] SRAP: Sidelink Relay Adaptation Protocol (Layer)

[0040] RRC: Radio Resource Control (layer)

[0041] RRC_CONNECTED: RRC connection state

[0042] RRC_INACTIVE: RRC inactive state

[0043] RRC_IDLE: RRC idle state

[0044] RAN: Radio Access Network

[0045] NG-RAN: NG Radio Access Network, a next-generation radio access network

[0046] gNB: the next generation Node B, next-generation base station

[0047] Sidelink: Side-link communication, side-link

[0048] SL: Sidelink, side-to-side communication, side-to-side link

[0049] SCI: Sidelink Control Information

[0050] AS: Access Stratum

[0051] IE: Information Element

[0052] CE: Control Element

[0053] MIB: Master Information Block

[0054] SIB: System Information Block

[0055] DCI: Downlink Control Information

[0056] RB: radio bearer

[0057] DRB: Data Radio Bearer

[0058] SRB: Signaling Radio Bearer

[0059] Uu: Open air

[0060] ProSe: Proximity-based Services

[0061] V2X: Vehicle-to-Everything.

[0062] NAS: Non-Access Stratum

[0063] PC5-S: PC5 signalling

[0064] SL-SRB: Sidelink Signalling Radio Bearer

[0065] SL-DRB: Sidelink Data Radio Bearer

[0066] U2U: UE-to-UE, UE to UE

[0067] U2N: UE-to-Network

[0068] L2: Layer 2, a two-layer architecture

[0069] RSRP: Reference Signal Received Power

[0070] SL-RSRP: Sidelink RSRP, the received power of the sidelink communication reference signal.

[0071] SD-RSRP: Sidelink Discovery RSRP, a reference signal received by sidelink communication.

[0072] SpCell: Special Cell, including PCCell and PSCell.

[0073] PCell: Primary Cell

[0074] PSCell: Primary SCG Cell, SCG main cell

[0075] L2-ID: Layer-2 ID (identity), the identifier for the second layer.

[0076] 3GPP: 3rd Generation Partnership Project

[0077] RLF: Radio link failure.

[0078] TMSI: Temporary Mobile Subscriber Identity

[0079] RNTI: Radio Network Temporary Identifier

[0080] In this invention, the network (or NW), base station (or gNB or eNB), and RAN are interchangeable. The network can be a Long Term Evolution (LTE) network, a New Radio Access Technology (New RAT, NR) network, an enhanced Long Term Evolution (eLTE) network, or other networks defined in subsequent 3GPP evolution versions. The base station in this invention can be any type of base station, including Node B, enhanced base station (eNB), 5G communication system base station (gNB); or micro base station, pico base station, macro base station, femto base station, etc.; the network generally refers to a base station or cell. The cell can also be a cell under any of the above-mentioned types of base stations. Unless otherwise specified, cell, beam, and transmission point (TRP) are interchangeable. The base station can also be the central unit (gNB-CU) or distributed unit (gNB-DU) that makes up the base station.

[0081] In this invention, the User Equipment (UE) may refer to the NR device that supports NR Sidelink relay function as described in the background art, or the NR device that supports L2 U2N relay function, or the NR device that supports multi-hop L2 U2N relay function, or other types of NR devices or LTE devices.

[0082] In this invention, Sidelink, SL, and PC5 can be used interchangeably.

[0083] In this invention, "change" and "update" can be used interchangeably.

[0084] In this invention, "configure", "set", and "present" can be used interchangeably.

[0085] In this invention, the terms "used", "available", "active", "applied", "performed", and "enabled" can be used interchangeably.

[0086] In this disclosure, the terms "use", "be available", "apply", "implement", "enable", "activate", "perform", and "do" can be used interchangeably.

[0087] In this disclosure, "associate", "correspond", and "map" can be used interchangeably.

[0088] In this disclosure, receive, detect, monitor, acquire, and derive are interchangeable.

[0089] In this invention, the terms "feedback", "submit", "report", "send", "transmit or transport", "inform", "indicate", "provide", and "forward" can be used interchangeably.

[0090] In this invention, "trigger" and "initiate" can be used interchangeably.

[0091] In this invention, the upper layer can refer to the ProSe layer, the V2X layer, the NAS layer, or the PC5-S protocol layer. The ProSe layer, V2X layer, NAS layer, and PC5-S protocol layer can be used interchangeably in this invention.

[0092] In this invention, "channel" can refer to one channel or multiple channels.

[0093] In this invention, "first hop", "second hop" and "third hop" can all be modified by "PC5", that is, "first hop", "second hop" and "third hop" are all based on the PC5 interface.

[0094] In this invention, “relay UE”, “U2N relay UE” and “L2U2N relay UE” can be used interchangeably, and “NR sidelink” can be added as a prefix to these names.

[0095] In this invention, “remote UE”, “U2N remote UE” and “L2U2N remote UE” can be used interchangeably, and “NR sidelink” can be added as a prefix to these names.

[0096] It should be noted that in this specification, the two terms connected by "and", "or", or "and / or" may represent different ways of expressing the same meaning in different application scenarios. There may be a relationship of inclusion between the two terms, and they do not necessarily refer to completely different content.

[0097] The related technologies of the present invention are described below.

[0098] PC5 connects to N

[0099] The PC5 interface is the interface for control plane and user plane sidelink communication between UEs. The upper layer(s) establishes PC5 unicast links for sidelink unicast communication; each PC5 unicast link establishment corresponds to a PC5-RRC connection establishment. For sidelink unicast, the PC5-RRC connection is an AS layer logical connection between a source L2ID and a destination L2ID.

[0100] Uu interface

[0101] The Uu interface is the wireless communication interface between the UE and the base station. The UE can use NR technology and gNB communication on the Uu interface.

[0102] L2 architecture

[0103] L2 architecture is relative to L3 architecture. In L2 architecture, the selection and reselection of relays, as well as communication between the UE and the network or another UE via relays, need to be controlled or controlled by the access layer. In contrast, in L3 architecture, the access layer is basically unaware of the existence of relays, or in other words, relays are transparent to the access layer.

[0104] U2N (UE-to-Network) relay

[0105] UE-to-Network relay, such as Figure 1 As shown, the left side represents the remote UE, the middle side represents the relay UE, and the right side represents the network. The remote UE and the relay UE establish a direct connection via the PC5 interface, while the relay UE and the network are directly connected via the Uu interface. Because the remote UE is far from the network or the communication environment is poor, the relay UE is needed to relay and forward signaling and data between the two.

[0106] For U2N trunk architecture, a U2N remote UE refers to a UE that communicates with the network through a U2N trunk UE. An L2 U2N remote UE refers to a U2N remote UE in an L2 architecture. A U2N trunk UE refers to a UE that provides functionality to support U2N remote UE connections to the network. An L2 U2N trunk UE refers to a U2N trunk UE in an L2 architecture.

[0107] After a remote UE selects a relay UE to provide relay services, it establishes a PC5-RRC connection with the relay UE to enable communication between the remote UE and the network. The remote UE can also establish an air interface RRC connection with the network via the relay UE for data transmission between the remote UE and the network.

[0108] like Figure 1 The L2U2N architecture shown is a single-hop U2N relay, meaning that the remote UE communicates with the network through a relay UE, or it can be called a single-hop relay to distinguish it from subsequent multi-hop relays.

[0109] Multi-hop U2N relay

[0110] A single-hop U2N relay only has one U2N relay UE, and its coverage is limited. Multi-hop U2N relays, such as... Figure 2 As shown, a U2N remote UE connects and communicates with the network through multiple U2N relay UEs. Multi-hop U2N relays can extend coverage. A U2N relay UE directly connected to the network can be called the "last U2N relay UE," or simply "last relay." For example... Figure 2 As shown, except for the last U2N relay UE, all other relay UEs can be called "intermediate relay UEs". Among these intermediate relay UEs, the intermediate UE that is directly connected to the remote UE can be called the "first relay UE" or the "first intermediate relay UE", or simply "first relay".

[0111] It is evident that in a multi-hop U2N trunk architecture, the trunk type of a trunk UE can be the first trunk, an intermediate trunk (not the first trunk), an intermediate trunk (including the first trunk and other intermediate trunks), or the last trunk. In a single-hop U2N trunk architecture, the trunk type of a trunk UE can only be the last trunk. Furthermore, the trunk type can be represented or determined in other ways. For example, it can indicate the connection method between the trunk and the network or base station. If the connection method is direct, the trunk UE's trunk type is the last trunk; if it's indirect, it's an intermediate trunk. Alternatively, it can indicate the connection method between the trunk and a remote UE. If the connection method is direct, the trunk UE's trunk type is the first trunk.

[0112] In this invention, the method of directly indicating the relay type is used as an example where "relay type" is involved, but it is equally applicable to cases where the relay type is determined indirectly by other means.

[0113] In a multi-hop U2N relay architecture, the number of intermediate relay UEs can be one or more.

[0114] For example, in a multi-hop U2N trunk architecture with an intermediate trunk UE, this intermediate trunk UE is the first trunk UE. It can connect to the remote UE through the PC5 interface, and it can also connect to the last U2N trunk UE through the PC5 interface. The last U2N trunk UE can connect to the network through the Uu interface.

[0115] For example, in a multi-hop U2N trunk architecture with two intermediate trunk UEs, the U2N remote UE is connected to the first trunk UE via the PC5 interface, the first intermediate trunk UE is connected to the second intermediate trunk UE via the PC5 interface, the second trunk UE is connected to the last U2N trunk UE via the PC5 interface, and the last U2N trunk UE is connected to the network via the Uu interface.

[0116] U2N establishes a (Uu)RRC connection between the remote UE and the network, a Uu SRB for transmitting signaling, and a Uu DRB for transmitting data.

[0117] Path switch

[0118] The connection established between a UE and the network for data transmission can be considered a data path or a data connection. A UE connecting to the network via the Uu interface can be considered a direct path. A UE connecting to the network via a relay UE can be considered an indirect path. Indirect paths can be established based on the aforementioned single-hop or multi-hop U2N relay architecture. A UE connecting to the network via different relay UEs can be considered different data paths. In special cases, even if the relay UE directly connected to the UE is the same, but the intermediate relay UE indirectly connected to the UE is not exactly the same, such paths can also be considered different data paths. Furthermore, even if the relay UE directly connected to the UE is the same, but the relay UE directly connected to the network is different, such paths can also be considered different data paths. A change in the data path is called a path switch. A UE in the RRCCONNECTED state can perform a path switch, which is initiated by the network. The data path before the path switch is the source path, and the data path after the path switch is the destination path. Path switching is divided into: direct-to-indirect path switch, indirect-to-direct path switch, and indirect-to-indirect pathwitch.

[0119] For direct-to-indirect and indirect-to-indirect path handovers, further subdivisions include single-hop to single-hop, single-hop to multi-hop, multi-hop to multi-hop, and multi-hop to single-hop path handovers. The network can configure measurement parameters for remote UEs in RRC CONNECTED state, and the remote UE reports measurement reports to the network. The network, referencing the measurement reports, decides whether to switch the remote UE to an alternative path to connect to the network. This "alternative path" can be an indirect path connecting to the network via one or more relay UEs. Once the network identifies a target relay UE, it prepares to initiate a path handover by configuring relevant parameters for the remote UE using an RRCReconfiguration message. The network sends an RRCReconfiguration message to the remote UE, initiating a path handover with an indirect path as the target by including the sl-PathSwitchConfig field in this message, which contains information about the target relay UE. After obtaining the target relay UE information, the remote UE can start timer T420 and simultaneously initiate PC5 connection establishment to the target relay UE. Once the PC5 connection is established, the remote UE sends an RRCReconfigurationComplete message to the network, which is forwarded to the network by the relay UE, completing the path handover process. Timer T420 stops when the remote UE successfully sends the RRCReconfigurationComplete message, i.e., when the remote UE receives PC5 RLC acknowledgment information for this message from the target relay UE. If T420 times out, meaning that the RRCReconfigurationComplete message was not successfully sent during the T420 execution period, the remote UE can assume that a path handover failure has occurred and thus initiate the RRC connection re-establishment process.

[0120] For indirect-to-direct path handover, the network sends an RRCReconfiguration message to the remote UE. This message contains synchronization information, such as information element (IE) synchronization reconfiguration (reconfigwithsync), but does not include the sl-PathSwitchConfig field. The remote UE releases the PC5 connection between itself and the source relay UE and sends an RRCReconfigurationComplete message to the network towards the target cell.

[0121] Notification process

[0122] During the notification process, the relay UE will send a message named NotificationMessageSidelink to the remote UE.

[0123] Relay UEs typically initiate the notification process under the following circumstances:

[0124] The relay UE detected a radio link failure (RLF) on the Uu interface;

[0125] The relay UE receives an RRC reconfiguration message containing synchronization information (ReconfigurationwithSync);

[0126] When a cell reselection occurs for a relay UE.

[0127] When a relay UE detects an RLF on the Uu interface and transmits a NotificationMessageSidelink message, the relay UE will set the indication type to Relay UE Uu RLF.

[0128] When a relay UE receives an RRC reconfiguration message containing synchronization information (ReconfigurationwithSync) and transmits a NotificationMessageSidelink message, the relay UE will set the indication type to Relay UEhandover (HO).

[0129] When a relay UE transmits a NotificationMessageSidelink message during a cell reselection, the relay UE will set the indication type to Relay UE Cell Reselection.

[0130] These indication types are included in the NotificationMessageSidelink message, which the relay UE delivers to the lower layer for transmission.

[0131] Discovery process

[0132] The discovery process is used to detect and identify other UEs near a given UE. It helps a remote UE select or reselect a suitable relay UE. There are two models for the discovery process: Model A and Model B. Model A is a declaration of "I am here." The relay UE broadcasts a RelayDiscoveryAnnouncement message, or Discovery message for short. Upon receiving this message, a nearby remote UE can determine whether to select the relay UE for U2N relay communication. Model B is a question-and-answer format, first asking "Who is there? Or are you there?". The remote UE broadcasts a RelayDiscoverySolicitation message. Upon receiving this message, the relay UE sends a Relay Discovery Response message. The remote UE then determines whether to select the relay UE for U2N relay communication based on the received response message.

[0133] In the following embodiments, the same nouns may represent the same meaning, and the same parameter names may represent the same meaning.

[0134] The present invention also includes other embodiments not mentioned herein, which may achieve other effects not mentioned herein, which is self-evident.

[0135] The following describes in detail embodiments of the present invention that address the above-mentioned problems.

[0136] Example

[0137] Scene 1

[0138] In scenarios where a remote UE operates under multi-hop relay services, it connects to the network side through at least one intermediate relay UE and one final relay UE, such as... Figure 3 As shown in (a).

[0139] The network side can switch the remote UE from a multi-hop relay-based indirect path to a single-hop relay-based indirect path, and this target relay UE is the same as the first relay UE in the remote UE's source path, such as... Figure 3 As shown in (b), both are UE-A, meaning that the relay UE directly connected to the remote UE remains unchanged before and after the handover.

[0140] Scene 2

[0141] In a scenario where the remote UE is in a single-hop relay service, it connects to the network side through a relay UE (named UE-A), such as... Figure 4 As shown in (a).

[0142] The network side can switch the remote UE from a single-hop relay-based indirect path to a multi-hop relay-based indirect path, and the first relay UE in this multi-hop relay-based indirect path is the same as the (last) relay UE in the remote UE's source path, such as... Figure 4 As shown in (b), both are UE-A, meaning that the relay UE directly connected to the remote UE remains unchanged before and after the handover.

[0143] To achieve the transition in either Scenario 1 or Scenario 2, the following steps can be taken.

[0144] Figure 5 This is a flowchart illustrating a method performed by the user equipment (UE) according to the present invention.

[0145] like Figure 5 As shown, in step 501, the remote UE receives an RRCReconfiguration message sent by the network side, which indicates in the reconfiguration information that the remote UE is performing a path handover or conversion, and the target path is a non-directly connected path. Specifically, the reconfiguration information may include an sl-PathSwitchConfig field; and preferably, the network side may indicate in the above reconfiguration information that the relay structure of the target path is a multi-hop relay. Preferably, if the relay structure is not indicated, or is in a default state, the relay structure of the target path can be considered as a single-hop relay. Such indication information can also be implemented by indicating the relay type of the target relay: for example, indicating that the relay type of the target relay is the first relay or an intermediate relay indicates that the relay structure of the target path is a multi-hop relay; if the relay type of the target relay is the last relay, or the relay type of the target relay is defaulted, it indicates that the relay structure of the target path is a single-hop relay. Here, the target relay refers to the relay UE that directly establishes a connection with the remote UE on the target path of the handover. Furthermore, the network can instruct the remote UE to maintain the connection with the relay UE (UE-A) with which it has a direct connection in the aforementioned reconfiguration information. Such instruction information can be represented by an information cell, for example, defining an information cell named relay_maintain.

[0146] In step 502, after the remote UE receives a cell named relay_maintain, at least one of the following operations can be performed:

[0147] -The serving cell of the relay UE directly connected to the current remote UE (i.e., the first relay UE on the source path, or the target relay UE) is considered the serving cell of the remote UE.

[0148] - Start timer T420, preferably with the duration set to the duration value of T420 contained in sl-PathSwitchConfig.

[0149] As a supplement, when the remote UE successfully sends the RRCReconfigurationComplete message, i.e., when the remote UE receives PC5 RLC acknowledgment information for the message from the target relay UE, at least one of the following operations is performed:

[0150] -Stop timer T420;

[0151] - Reset the MAC entity used in the source cell.

[0152] Preferably, the RRCReconfiguration message received by the remote UE may include, in addition to the relay_maintain information element, an indication message to indicate whether the remote UE needs to start timer T420. For example, this indication message could be an information element named timer start. The UE can start timer T420 after receiving this information element; if the RRC reconfiguration message does not carry this information element, then timer T420 will not be started.

[0153] Figure 6 This is a flowchart illustrating method two executed by the user equipment (UE) of the present invention.

[0154] like Figure 6 As shown, in step 601, the remote UE receives the RRCReconfiguration message sent by the network side. The reconfiguration information includes the sl-PathSwitchConfig field and an information element named relay_maintain. The reconfiguration information may or may not include the information element timer_start, which is used to indicate whether to start timer T420.

[0155] In step 602, after receiving the reconfiguration message, the remote UE may perform at least one of the following operations:

[0156] -The serving cell of the relay UE directly connected to the current remote UE (i.e., the first relay UE on the source path, or the target relay UE) is considered the serving cell of the remote UE.

[0157] - If the reconfiguration message also contains the information element "timer start", then the remote UE starts timer T420. Otherwise, if the information element is not included, the remote UE does not start timer T420.

[0158] As a supplement, when the remote UE successfully sends the RRCReconfigurationComplete message, that is, when the remote UE receives PC5 RLC confirmation information for the message from the target relay UE, at least one of the following operations can be performed:

[0159] - If timer T420 is running, then stop running T420; and

[0160] - Reset the MAC entity used in the source cell.

[0161] It should be noted that the instruction of the information cell timer_start can also mean not to start the T420. Therefore, a variation of the above implementation method could be:

[0162] - If the reconfiguration message also contains the information element timer_start, then the remote UE will not start timer T420. Otherwise, if the information element is not included, the remote UE will start timer T420.

[0163] Alternatively, the network side can implicitly indicate whether T420 needs to be started. For example, the remote UE can determine whether T420 needs to be started by checking whether the T420 duration configuration information is included in the RRC reconfiguration message. If the reconfiguration information does not contain the T420 duration value, the remote UE does not start timer T420. Conversely, if the T420 duration configuration information is included, the remote UE starts timer T420.

[0164] Specific implementation methods may also be described below.

[0165] The remote UE receives the RRCReconfiguration message sent by the network side. This reconfiguration information includes the sl-PathSwitchConfig field and an information element named relay_maintain. This reconfiguration information may or may not include configuration information for timer T420, such as the duration value of T420, which is used to indicate whether timer T420 should be started.

[0166] Upon receiving this reconfiguration message, the remote UE may perform at least one of the following operations:

[0167] - The serving cell of the relay UE directly connected to the current remote UE (i.e., the first relay UE on the source path, or the target relay UE) is considered the serving cell of the remote UE; and

[0168] - If the reconfiguration message also contains configuration information for timer T420, specifically the T420 duration value, then timer T420 is started, and its duration is set to the T420 duration value contained in sl-PathSwitchConfig. Otherwise,

[0169] If this value information is not included, the remote UE will not start timer T420.

[0170] As a supplement, when the remote UE successfully sends the RRCReconfigurationComplete message, that is, when the remote UE receives PC5 RLC acknowledgment information for the message from the target relay UE, the remote UE may perform at least one of the following operations:

[0171] - If timer T420 is running, then stop running T420; and

[0172] - Reset the MAC entity used in the source cell.

[0173] In addition to the operations mentioned above, the following operations can also be performed.

[0174] Figure 7 This is a flowchart illustrating method three executed by the user equipment (UE) of the present invention.

[0175] like Figure 7 As shown, in step 701, UE-A receives an RRCReconfiguration message sent by the network side, which includes a cell reconfigurationWithSync indicating synchronization configuration.

[0176] In step 702, after receiving the above reconfiguration information, the relay UE-A initiates a notification process. In the notification process, the relay UE-A sets the indication type to relay UE handover (HO) in the NotificationMessageSidelink message, and then submits the NotificationMessageSidelink message to the lower layer for transmission to the remote UE.

[0177] After receiving the above reconfiguration information or after executing the reconfiguration information, UE-A can also determine its relay type:

[0178] If the relay type of UE-A is intermediate relay, then the aforementioned NotificationMessageSidelink message can include indication information indicating that its relay type is intermediate relay;

[0179] If the UE-A's relay type is the last relay, then the aforementioned NotificationMessageSidelink can include indication information to indicate that its relay type is the last relay, or it can be indicated by the default relay type (i.e., without including relay type indication information, implicit indication) to indicate that its relay type is the last relay.

[0180] UE-A can determine its relay type through at least the following methods:

[0181] UE-A determines whether the sl-PathSwitchConfig field is included in the RRCReconfiguration message. If the result is that the field is not included (or the field is defaulted), then it can be determined that it is the last trunk, and the trunk type can also be indicated as the last trunk in the NotificationMessageSidelink message. If the result is that the field is included, then it can be determined that it is an intermediate trunk, and the trunk type can also be indicated as an intermediate trunk in the NotificationMessageSidelink message.

[0182] Alternatively, UE-A can determine its relay type by judging the type of handover that occurred:

[0183] If the switching type that occurs is from a direct path to a non-direct path, or from a non-direct path to a non-direct path, then the relay type can be determined to be an intermediate relay, and the relay type can also be indicated as an intermediate relay in the NotificationMessageSidelink message.

[0184] If the switching type is from a non-direct path to a direct path, or from a direct path to a direct path, then the relay type can be determined as the last relay, and the relay type can be explicitly or implicitly indicated as the last relay in the NotificationMessageSidelink message.

[0185] As a remote UE, upon receiving the aforementioned NotificationMessageSidelink message, it can perform the following operations:

[0186] The remote UE can decide to continue the PC5 connection with UE-A, and preferably, it can be considered that a handover or path switch has occurred.

[0187] The remote UE can also decide to release the PC5 connection with UE-A, and then instruct the upper layer to trigger the release of the PC5 connection.

[0188] The remote UE can determine whether to maintain a connection with UE-A based on configuration or indication information sent by the network side. One feasible approach is to include indication information for maintaining a connection with UE-A in the RRC message received by the remote UE from the network side. This could be the aforementioned relay_maintain element, or other information indicating the need to maintain a PC5 connection. Based on this indication information, the remote UE can decide to continue maintaining a PC5 connection with UE-A upon receiving the aforementioned NotificationMessageSidelink message.

[0189] The aforementioned solutions can be combined or executed separately to achieve the switching between scenario one and scenario two.

[0190] In addition, for scenario two, the following operations are also possible:

[0191] UE-A receives an RRCReconfiguration message sent by the network side, which includes reconfigurationWithSync.

[0192] Upon receiving the aforementioned reconfiguration information, UE-A initiates the notification process. During this process, UE-A sets the indication type to relay UE handover (HO) in the NotificationMessageSidelink message, and then submits this NotificationMessageSidelink message to the lower layer for transmission to the remote UE.

[0193] In one scenario, the reconfiguration information indicates a path switch targeting a non-direct path, i.e., it includes the sl-PathSwitchConfig field. In this case, in the NotificationMessageSidelink message mentioned above, in addition to setting the indication type as relay UE handover (relay UE HO), further indication information can be set to indicate that the handover targets a non-direct connection path. For example, it can include the information element indirect_path to indicate that the handover is a non-direct connection. Alternatively, it can set indication information to indicate that UE-A has become an intermediate relay, such as including the information element intermediate_relay.

[0194] As a supplement, if the sl-PathSwitchConfig field is not included in the above reconfiguration information, then it is only necessary to set the indication type to relay UE handover (relay UE HO).

[0195] Another possible implementation of the above solution is:

[0196] When UE-A receives an RRCReconfiguration message containing reconfigurationWithSync, a notification procedure is initiated. During the notification procedure,

[0197] UE-A further determines whether the sl-PathSwitchConfig field is included in the RRCReconfiguration message. If the result is that the field is not included, the indication type is set to relay UE HO in the NotificationMessageSidelink message. If the result is that the field is included, the indication type is set to relay UE indirect HO in the NotificationMessageSidelink message. Then, the NotificationMessageSidelink message is delivered to the lower layer for transmission to the remote UE.

[0198] Alternatively, UE-A may further determine whether the RRCReconfiguration message contains the sl-PathSwitchConfig field. If the result is that the field is not included, then the indication type in the NotificationMessageSidelink message is set to relay UE handover (relay UE HO). If the result is that the field is included, then the NotificationMessageSidelink message contains information indicating that the relay UE has become an intermediate relay, such as including the information element intermediate_relay, and then the message is...

[0199] The NotificationMessageSidelink is handed over to the lower layer for transmission to the remote UE.

[0200] As a remote UE, upon receiving the aforementioned NotificationMessageSidelink message, it can perform corresponding operations based on the information contained within it:

[0201] If the received NotificationMessageSidelink message contains an indication type, and does not contain other information indicating that the handover is an indirect handover (e.g., it does not contain the indirect_path cell) or information indicating that the relay UE becomes an intermediate relay (e.g., it does not contain the intermediate_relay cell), then the UE can initiate the RRC connection re-establishment procedure.

[0202] If the received NotificationMessageSidelink message contains an indication that the handover is aimed at a non-direct connection, such as the information cell indirect_path, then the UE may not initiate the RRC connection re-establishment procedure. Alternatively, the remote UE may consider the current relay UE as the first relay UE (or the first intermediate relay UE).

[0203] If the received NotificationMessageSidelink message contains information indicating that the relay UE has become an intermediate relay, such as the information element intermediate_relay, then the remote UE may not initiate the RRC connection re-establishment procedure. Optionally, the remote UE may consider the current relay UE as the first relay UE (or the first intermediate relay UE).

[0204] If the received NotificationMessageSidelink message contains an indication type, and this indication type is not a relay UE indirect HO handover, then the UE can initiate the RRC connection re-establishment procedure.

[0205] If the received NotificationMessageSidelink message contains an indication type, and this indication type is indirect HO handover between relay UEs, then the remote UE may not initiate the RRC connection re-establishment procedure. Alternatively, the remote UE may consider the current relay UE as the first relay UE (or the first intermediate relay UE).

[0206] Prior to this, the remote UE here is the UE in RRC connected state.

[0207] To avoid unnecessary RRC connection re-establishment for remote UEs, another feasible approach is for UE-A to determine whether the sl-PathSwitchConfig field is also included in the RRCReconfiguration message containing reconfigurationWithSync when it receives the message. If the result is that the sl-PathSwitchConfig field is not included, then UE-A initiates the notification process; if the result is that the sl-PathSwitchConfig field is included, then UE-A does not initiate the notification process.

[0208] Another possible implementation is to initiate a notification process when the UE-A receives an RRCReconfiguration message containing reconfigurationWithSync. In the notification process, the UE-A determines whether the message also contains the sl-PathSwitchConfig field.

[0209] If the determination result is that the field is not included, UE-A sends a NotificationMessageSidelink message to all remote UEs connected to it, and in that...

[0210] In the NotificationMessageSidelink message, the indication type is set to relay UE handover (relayUEHO);

[0211] When the result of the judgment includes this field, UE-A sends a NotificationMessageSidelink message to all remote UEs connected to it that are in a non-RRC connection state (e.g., remote UEs in idle state (RRC IDLE) or inactive state (RRC INACIVE)), and sets the indication type to relay UE HO in the NotificationMessageSidelink message:

[0212] When the result of the judgment includes this field, UE-A can also send a NotificationMessageSidelink message to all remote UEs connected to it in the RRC connection state (e.g., remote UEs that are not in the idle state or not in the inactive state), and set the indication type to relay UE handover in the NotificationMessageSidelink message, and include the aforementioned information element intermediate_relay or indirect_path in the message.

[0213] Here, UE-A can learn whether the remote UE connected to it is in RRC idle state, RRC inactive state, or RRC connected state through other means, without any restrictions.

[0214] In Scenario 1, the first relay UE becomes the last relay UE; in Scenario 2, the last relay UE becomes the first relay UE. This demonstrates that the relay type of a relay UE can change; it can change from an intermediate relay to the last relay, or vice versa. Such role changes affect the remote UEs served by that relay UE that are in RRC idle or RRC inactive states.

[0215] When a relay UE acts as the first relay UE, remote UEs directly connected to it via PC5, if in RRC idle or RRC inactive state, will send paging-related information (hereinafter referred to as "paging information") to the first relay UE. Upon receiving paging information from remote UEs, the first relay UE can forward this or these remote UE paging information to the next intermediate relay UE or the last relay UE with which it has established a connection. Ensuring the transmission of paging information when the relay UE's relay type changes is also a problem that needs to be addressed. Correct transmission of paging messages is essential to guarantee service continuity.

[0216] When the relay UE undergoes a relay type change, such as a handover occurring in the aforementioned scenario one or scenario two, the following processing can be performed:

[0217] Method 1: The relay UE can include indication information in the PC5 message, indicating whether the relay UE's relay type is an intermediate relay or a last relay. If a change occurs, the PC5 message is updated and then sent. Preferably, this PC5 message can be a Discovery message or a response message from the discovery process. Alternatively, the relay UE can include information in the NotificationMessageSidelink message, which can include relay type information or information about a change in relay type.

[0218] For example, when a relay UE acts as an intermediate relay UE, its broadcast Discovery message or NotificationMessageSidelink message can indicate that its relay type is intermediate relay; when the relay UE becomes the last relay UE, its broadcast Discovery information is changed to indicate that its relay type is last relay, or in

[0219] The NotificationMessageSidelink indicates that its relay type is the last relay.

[0220] For a remote UE connected to the relay UE, after learning that the relay UE's relay type has changed to last relay, if the remote UE has paging information to provide, it can send its paging information to the relay UE again. Here, "again" means compared to before, when the remote UE had already sent its paging information to the relay UE when the relay UE was still acting as an intermediate relay UE.

[0221] In a specific implementation, when a remote UE learns or determines that the trunk type of a connected trunk UE has changed (e.g., from intermediate trunk to last trunk, or vice versa), and if the remote UE needs to provide paging information, it can send its paging information to that trunk UE. Such paging information can be included in a PC5 RRC message; preferably, it can be included in...

[0222] The paging information in the RemoteUEInformationSidelink message may include the remote UE's TMSI information and / or RNTI information. The remote UE can determine whether the relay type of the relay UE has changed by comparing the relay type contained in messages sent by the relay UE at different times. For the same relay UE, the remote UE can receive the relay type for the first time from the Discovery message or response message. For example, if the received relay type is intermediate relay, and the relay type can be received a second time from the NotificationMessageSidelink message, if it is still intermediate relay, it means that the relay type received the second time is the same as the relay type received the first time, and a paging message does not need to be provided again; if it is already the last relay, it means that the relay type received the second time is different from the relay type received the first time, and a paging message can be provided again.

[0223] Upon receiving paging information from a remote UE, the relay UE determines how to transmit these paging messages based on its relay type: In one scenario, if the relay UE's current relay type is intermediate relay, it can include the paging information in the first PC5 RRC message and deliver it to the lower layer for transmission, either to a connected intermediate relay UE or to a connected last relay UE. In another scenario, if the relay UE's current relay type is last relay, it can include the paging information in the first RRC message and deliver this RRC message to the lower layer for transmission, either to the network or the base station. Preferably, this RRC message is...

[0224] SidelinkUEInforamtionNR message.

[0225] Specifically, if the paging information received by the relay UE is set to release, then in one scenario, if the relay UE's current relay type is intermediate relay, the relay UE can initiate the transmission of a first PC5 RRC message to release the paging information of the remote UE. This PC5 RRC message will be delivered to the lower layer for transmission, either to the connected intermediate relay UE or to the connected last relay UE. In another scenario, if the relay UE's current relay type is last relay, the relay UE can initiate the transmission of a SidelinkUEInforamtionNR message to release the paging information of the remote UE. The SidelinkUEInforamtionNR message will be delivered to the lower layer for transmission, either to the network or the base station.

[0226] Method 2: When the relay UE's relay type changes, for example from intermediate relay to last relay, the relay UE can initiate the transmission of a SidelinkUEInforamtionNR message. This message contains paging information previously received by the relay UE from one or more remote UEs. The SidelinkUEInforamtionNR message will be delivered to the lower layer for transmission to the network or base station. When the relay UE's relay type changes, for example from last relay to intermediate relay, the relay UE can initiate the transmission of a first PC5 RRC message. This PC5 RRC message contains paging information previously received by the relay UE from one or more remote UEs. This message will be delivered to the lower layer for transmission to either the connected intermediate relay UE or the connected last relay UE.

[0227] A trunk UE can determine whether a trunk type change has occurred in the following ways.

[0228] A relay UE can determine whether its relay type has changed by receiving an RRC reconfiguration message containing handover information. For example, if a relay UE receives an RRC reconfiguration message containing the sl-PathSwitchConfig field, indicating a switch to a non-direct path, and if the relay UE was in a direct connection mode with the base station before receiving this RRC reconfiguration message, then the relay UE can determine that its relay type has changed from last relay to intermediate relay. As another example, if a relay UE receives an RRC reconfiguration message containing synchronization information (reconfigurationWithSync) but not the sl-PathSwitchConfig field, and this reconfiguration information indicates a switch to a direct path, if the relay UE was in a non-direct connection mode with the base station before receiving this RRC reconfiguration message, then the relay UE can determine that its relay type has changed from intermediate relay to last relay after the handover; if the relay UE was in a direct connection mode with the base station before receiving this RRC reconfiguration message, then the relay UE can determine that its relay type remains last relay after the handover, and has not changed.

[0229] The relay UE can also determine its relay type using the following methods:

[0230] The relay UE determines whether the received RRCReconfiguration message contains the sl-PathSwitchConfig field. If the result is that the field is not included (or the field is defaulted), then it can be determined that it is the last relay, and the relay type can also be indicated as the last relay in the NotificationMessageSidelink message. If the result is that the field is included, then it can be determined that it is an intermediate relay, and the relay type can also be indicated as an intermediate relay in the NotificationMessageSidelink message.

[0231] Alternatively, the relay UE can determine its relay type by judging the type of handover that occurred:

[0232] If the switching type is from a direct path to a non-direct path, or from a non-direct path to a non-direct path, then the relay type can be determined to be an intermediate relay.

[0233] If the switching type is from a non-direct path to a direct path, or from a direct path to a direct path, then the relay type can be determined to be the last relay.

[0234] A relay UE can also determine whether its relay type has changed through cell selection and reselection, as well as relay selection and reselection. Such a relay UE is generally in RRC idle state (RRCCIDLE) or RRC inactive state (RRCINACIVE). When the relay UE, after cell selection and reselection, camps on a serving cell, its current relay type can be determined as the last relay. Due to changes or fluctuations in signal strength, when the relay UE, after relay selection and reselection, selects another relay UE as its serving relay and establishes a PC5 connection with that relay, then the relay UE's relay type changes to intermediate relay.

[0235] Figure 8 This is a simplified structural block diagram of the user equipment (UE) involved in this invention. Figure 8 As shown, the user equipment UE800 includes a processor 801 and a memory 802. The processor 801 may include, for example, a microprocessor, a microcontroller, an embedded processor, etc. The memory 802 may include, for example, volatile memory (such as random access memory, RAM), a hard disk drive (HDD), non-volatile memory (such as flash memory), or other memory. Program instructions are stored on the memory 802. When executed by the processor 801, these instructions can perform the methods described in detail herein, executed by the user equipment.

[0236] Additionally, the computer-executable instructions or program running on the device according to this disclosure may be a program that enables the computer to perform the functions of the embodiments of this disclosure by controlling the central processing unit (CPU). The program or the information processed by the program may be temporarily stored in volatile memory (such as random access memory, RAM), hard disk drive (HDD), non-volatile memory (such as flash memory), or other memory systems.

[0237] Computer-executable instructions or programs for implementing the functions of the embodiments of this disclosure can be recorded on a computer-readable storage medium. The corresponding functions can be implemented by causing a computer system to read and execute the programs recorded on the recording medium. The term "computer system" herein can refer to a computer system embedded in the device, and may include an operating system or hardware (such as peripheral devices). "Computer-readable storage medium" can be a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a short-time dynamic program storage medium, or any other computer-readable recording medium.

[0238] Various features or functional modules of the devices used in the above embodiments can be implemented or executed by circuits (e.g., monolithic or multi-chip integrated circuits). Circuits designed to perform the functions described in this specification may include general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of the above devices. A general-purpose processor may be a microprocessor, or any existing processor, controller, microcontroller, or state machine. The circuits described above may be digital circuits or analog circuits. In cases where advancements in semiconductor technology have led to new integrated circuit technologies that replace existing integrated circuits, one or more embodiments of this disclosure may also be implemented using these new integrated circuit technologies.

[0239] Furthermore, this disclosure is not limited to the embodiments described above. Although various examples of the embodiments have been described, this disclosure is not limited thereto. Fixed or non-mobile electronic devices installed indoors or outdoors can be used as terminal devices or communication devices, such as AV equipment, kitchen equipment, cleaning equipment, air conditioners, office equipment, vending machines, and other household appliances.

[0240] As described above, embodiments of this disclosure have been described in detail with reference to the accompanying drawings. However, the specific structure is not limited to the above embodiments, and this disclosure also includes any design modifications that do not depart from the spirit of this disclosure. Furthermore, various modifications can be made to this disclosure within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of this disclosure. In addition, components with the same effects described in the above embodiments can be substituted for each other.

Claims

1. A method performed by a remote user equipment (UE), comprising the following steps: The system receives an RRC reconfiguration message sent by the network side. The RRC reconfiguration message includes first indication information for initiating a path handover targeting a non-direct path, and second indication information for instructing the remote UE to maintain its connection with a relay UE on the source path that is directly connected to the remote UE. Upon receiving the RRC reconfiguration message, perform at least one of the following operations: - The serving cell of the relay UE is considered to be the serving cell of the remote UE; and - Start a timer to confirm whether the RRC reconfiguration completion message has been successfully sent.

2. The method according to claim 1, wherein, If the remote UE successfully sends the RRC reconfiguration complete message, perform at least one of the following operations: - Stop the timer; and - Reset the MAC entity used in the source cell.

3. A method performed by a remote user equipment (UE), comprising the following steps: The system receives an RRC reconfiguration message sent by the network side. The RRC reconfiguration message includes a first indication for initiating a path handover targeting a non-direct path, a second indication for instructing the remote UE to maintain its connection with a relay UE directly connected to the remote UE on the source path, and a third indication for starting a timer to confirm whether the RRC reconfiguration completion message has been successfully sent. Upon receiving the RRC reconfiguration message, perform at least one of the following operations: - The serving cell of the relay UE is considered to be the serving cell of the remote UE; and - If the third indication message indicates that the timer should be started, then start the timer.

4. The method according to claim 3, wherein, If the third indication indicates that the timer should not be started, then the timer will not be started.

5. The method according to claim 3, wherein, If the remote UE successfully sends the RRC reconfiguration complete message, perform at least one of the following operations: - If the timer is running, then stop the running timer; and - Reset the MAC entity used in the source cell.

6. A method performed by a relay UE directly connected to a remote user equipment (i.e., a remote UE), comprising the following steps: Receive an RRC reconfiguration message sent by the network side, wherein the RRC reconfiguration information includes synchronization information; and Upon receiving the RRC reconfiguration message, the relay UE initiates the following notification procedure: setting the indication type to relay UE handover in the notification message, and transmitting the notification message to the remote UE.

7. The method according to claim 6, wherein, The notification message also includes indication information indicating whether the relay UE is an intermediate relay or a last relay.

8. A user equipment, comprising: processor; as well as Memory, which stores instructions The instructions, when executed by the processor, perform the method according to any one of claims 1 to 6.

Images