WO2023093818A1

WO2023093818A1 - Method executed by user equipment and user equipment

Info

Publication number: WO2023093818A1
Application number: PCT/CN2022/134184
Authority: WO
Inventors: 张崇铭; 刘仁茂
Original assignee: 夏普株式会社; 张崇铭
Priority date: 2021-11-25
Filing date: 2022-11-24
Publication date: 2023-06-01
Also published as: CN116170898A

Abstract

The present invention provides a method executed by a user equipment (UE) and a UE. The method is a method executed when the UE establishes an RRC connection with a base station by means of a relay UE to be in an RRC connected state, and comprises the following steps: the UE receiving an RRC connection reconfiguration message from the base station, the reconfiguration message indicating that the UE executes a synchronization reconfiguration; when the UE receives the RRC connection reconfiguration message, starting a timer T304 for managing a handover or a synchronization reconfiguration; and when the timer T304 expires, the UE restoring an original configuration, i.e., a configuration used before the reconfiguration message is received, and starting an RRC connection reestablishment process, wherein the original configuration restored by the UE does not comprise a related configuration of PC5.

Description

Method performed by user equipment and user equipment

technical field

The present invention relates to the technical field of wireless communication, and more specifically, the present invention relates to a method executed by user equipment and corresponding user equipment.

Background technique

In a cell covered by a base station, a user equipment UE can directly communicate with the base station, and such a communication connection is called a direct connection (direct connection). The UE can also communicate with the base station through a relay UE (relay UE), and this connection can be called an indirect connection (indirect connection). In the scenario where the relay UE communicates with the base station, the UE is called a remote UE (remote UE).

In order to ensure the continuity of communication services, the UE indirectly connected to the base station through the relay UE can perform handover (switch/handover) under the instruction of the base station, so as to realize the direct connection with the base station. Such handover can be called indirect Connect to Direct Connect toggle.

UE may fail in the process of handover from indirect connection to direct connection. For example, the timer T304 for managing the handover runs out, indicating that this handover fails. Then the UE will restore the original configuration and perform the RRC connection re-establishment process. During the connection re-establishment process, the UE can perform cell reselection and relay reselection.

In one case, the UE experiencing the above-mentioned handover failure selects a cell to initiate an RRC connection re-establishment process. However, when the UE runs out of T304, it restores the original configuration. Since the original configuration is suitable for the scenario where the UE is indirectly connected to the base station through the relay, then when the UE reselects a cell and needs to directly connect to the base station , the original configuration cannot be used, which leads to the failure of re-establishment. This is a problem that needs to be solved.

Contents of the invention

In order to solve the above problem, the present invention provides a method executed by user equipment capable of avoiding re-establishment failure and user equipment.

According to one aspect of the present invention, a method performed by a user equipment is provided, which is a method performed by the user equipment UE in the RRC connection state after establishing an RRC connection with the base station through the relay UE, including the following steps:

The UE receives an RRC connection reconfiguration message from the base station, and the reconfiguration message indicates that the UE performs synchronous reconfiguration;

When the UE receives the RRC connection reconfiguration message, it starts a timer T304 for managing handover or synchronous reconfiguration;

When the timer T304 expires, the UE restores the original configuration, that is, the configuration used before receiving the above-mentioned reconfiguration message, and starts the RRC connection re-establishment process, wherein the original configuration restored by the UE does not include the relevant configuration of PC5 .

In the above method performed by the user equipment, preferably,

The above reconfiguration message instructs the UE to switch from an indirect connection via a relay to a direct connection via a cell.

In the above method performed by the user equipment, preferably,

The above original configuration is the configuration received by the UE from the base station side under the indirect connection via the relay.

In the above method performed by the user equipment, preferably,

When the timer T304 runs overtime, the UE judges whether it is in an indirect connection via a relay before,

If the UE is in the indirect connection via the relay, then the UE restores the original configuration except the related configuration of PC5 above, and starts the RRC connection re-establishment procedure.

In the above method performed by the user equipment, preferably,

The foregoing reconfiguration message indicates information that the UE is synchronized to a cell.

In the above method performed by the user equipment, preferably,

The original configuration above is the configuration of the source cell.

In the above method performed by the user equipment, preferably,

When the timer T304 expires, the UE restores the configuration used in the source cell and starts the RRC connection re-establishment process.

In the above method performed by the user equipment, preferably,

During the RRC connection re-establishment process, if the UE is not connected to the relay UE, then the UE releases the existing configuration related to PC5.

In the above method performed by the user equipment, preferably,

During the RRC connection re-establishment process, if the UE is not connected to the relay UE, then the UE further determines the reason for triggering the RRC connection re-establishment.

According to another aspect of the present invention, a user equipment is provided, including:

processor; and

a memory on which instructions are stored,

The above-mentioned instructions, when executed by the above-mentioned processor, cause the above-mentioned user equipment to perform the method according to the above-mentioned description.

According to the method executed by the user equipment involved in the present invention and the corresponding user equipment, re-establishment failure can be avoided.

Description of drawings

FIG. 1 is a schematic diagram showing UE-to-Network relay.

Fig. 2 is a schematic diagram showing the control plane protocol stack of UE-to-Network L2 architecture.

Fig. 3 shows a method executed by a user equipment UE according to an embodiment of the present invention.

Fig. 4 is a brief structural block diagram of the user equipment UE involved in the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the present invention should not be limited to the specific embodiments described below. In addition, for the sake of brevity, detailed descriptions of known technologies that are not directly related to the present invention are omitted to prevent confusion to the understanding of the present invention.

Some terms involved in the present invention are described below, and the specific meanings of the terms can be found in the latest standard specification of 3GPP.

RedCap: Reduced capability function decline

UE: User Equipment User Equipment

NR: New Radio, a new generation of wireless technology

MAC: Medium Access Control Multimedia Access Control

MAC CE: MAC control element MAC control element

RLC: Radio Link Control Wireless Link Control

SDAP: Service Data Adaptation Protocol Service Data Adaptation Protocol

PDCP: Packet Data Convergence Protocol Packet Data Convergence Protocol

RRC: Radio Resource Control Radio Resource Control

RRC_CONNECTED: RRC connected state

RRC_INACTIVE: RRC inactive state

RRC_IDLE: RRC idle state

RAN: Radio Access Network, wireless access network

Sidelink: sidelink communication

SCI: Sidelink Control Information, side link communication control information

AS: Access Stratum, access layer

IE: Information Element, information element

CE: Control Element, control element

MIB: Master Information Block, master information block

NR: New Radio, new radio

SIB: System Information Block, system information block

NG-RAN: NG Radio Access Network, a new generation of radio access network

DCI: Downlink Control Information, downlink control information

ADAPT: Adaptation layer, side link communication adaptation layer

PHY: physical layer, physical layer

RB: radio bearer, wireless bearer

DRB: Data Radio Bearer, data radio bearer

SRB: Signaling Radio Bearer, signaling radio bearer

PDU: Protocol Data Unit Protocol Data Unit

SDU: Service Data Unit service data unit

V2X: Vehicle-to-Everything Internet of Vehicles

CCCH: Common Control Channel public control channel

DCCH: Dedicated Control Channel dedicated control channel

In the present invention, the network, base station and RAN can be used interchangeably, and 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 a subsequent evolution version of 3GPP Other networks defined in .

In the present invention, the user equipment UE may refer to the NR equipment supporting the NR Sidelink relay function described in the background technology, or may refer to the NR equipment supporting the NR sidelink relay architecture, or may refer to other types of NR equipment or LTE equipment.

In the present invention, sidelink and PC5 can be used interchangeably, and RLC channel (channel), RLC entity and RLC bearer (bearer) can be used interchangeably. And in this paper, PC5 is used for relay operation, so it can also be replaced by relay.

Hereinafter, a description will be given of related art of the present invention.

The PC5 interface is an interface for Sidelink communication between the UE and the UE on the control plane and the user plane. For Sidelink unicast, the PC5-RRC connection is an AS layer logical connection between a pair of source layer 2 IDs and target layer 2 IDs. The establishment of a PC5 unicast link corresponds to the establishment of a PC5-RRC connection.

UE-to-Network relay is shown in Figure 1. In scenarios 1 and 2, the remote UE is on the left, the relay UE is in the middle, and the network is on the right; in scenario 3, the networks are on both sides, and the middle is from the left To the right are the remote UE and the relay UE. The remote UE is connected to the relay UE through the PC5 interface, and the relay UE is connected to the network through the Uu interface. Since the remote UE is far away from the network or the communication environment is not good, the relay UE needs to relay and forward the signaling and data between the two.

Scenarios for UE-to-Network relay include:

1) The Remote UE is outside the coverage area, and the Relay UE is within the coverage area (Scenario 1 shown in Figure 1);

2) Both the Remote UE and the Relay UE are within coverage and in the same cell (Scene 2 shown in Figure 1);

3) Both the Remote UE and the Relay UE are within coverage, but in different cells (Scenario 3 shown in Figure 1).

For the sidelink communication Layer 2 (L2) relay architecture, the control plane protocol stacks of remote UE, relay UE and base station are shown in Figure 2.

After the Remote UE selects a relay UE to provide relay services for itself, it will establish a PC5-RRC connection with the relay UE to communicate with the network through the relay UE. The remote UE can establish an air interface RRC connection with the network through the relay UE for data transmission between the remote UE and the network. The Remote UE will send the air interface RRC connection setup (setup), re-establishment (re-establish), and resume (resume) messages to the network to encapsulate the data through the Uu PDCP layer, and then submit it to the PC5 RLC entity for further encapsulation, and carry it on the PC5 RLC On the channel, it is submitted layer by layer through PC5-MAC and PC5-PHY. After the relay UE receives the data carrying the message, it submits it layer by layer through the PC5-PHY and PC5-MAC. The relay UE finds the Uu RLC channel carrying the message through the mapping relationship between the PC5 RLC channel and the Uu RLC channel, and sends the Messages are encapsulated in Uu messages/data and sent to the network. Conversely, the base station encapsulates the RRC message returned by the network into the Uu message/data and sends it to the relay UE. The relay UE finds the PC5 RLC channel carrying the message through the mapping relationship between the PC5 RLC channel and the Uu RLC channel, and transmits the message Encapsulated in PC5 message/data and sent to remote UE. When the Remote UE initiates RRC connection establishment, re-establishment, and recovery processes to the network, Uu RLC/MAC and PC5 RLC/MAC also need to perform corresponding processing in order to correctly transmit data when needed and stop data transmission in time when not needed. Conversely, the network can also release and suspend the air interface RRC connection to the remote UE through the relay UE. In these processes, Uu RLC/MAC and PC5 RLC/MAC also need to be processed accordingly.

SRB0 message

On the Uu interface, the UE sends an RRC connection establishment request message, an RRC connection re-establishment request message, and an RRC connection recovery request message to the base station through SRBO. Among them, SRB0 is used to bear RRC messages transmitted by using a logical channel whose logical channel type is CCCH (SRB0 is for RRC messages using the CCCH logical channel). It can be seen that the RRC connection establishment request message, the RRC connection re-establishment request message, and the RRC connection recovery request message all belong to such RRC messages transmitted using a logical channel whose logical channel type is CCCH. In this document, the RRC message transmitted on SRB0 may be referred to as SRB0 message (SRB0 message) for short.

SRB1 message

On the Uu interface, the UE sends an RRC connection recovery request message to the base station through SRBO. As a response message, the base station may send an RRC connection recovery message to the UE through SRB1. Or the UE sends an RRC re-establishment request message to the base station through SRB0. As a response message, the base station may send an RRC re-establishment message to the UE through SRB1. Wherein, SRB1 is used to carry RRC messages transmitted using a logical channel whose logical channel type is DCCH (SRB1 is for RRC messages using the DCCH logical channel). It can be seen that both the RRC connection recovery message and the RRC connection re-establishment message belong to such RRC messages transmitted using a logical channel whose logical channel type is CCCH. In this document, the RRC message transmitted on SRB1 may be referred to as SRB1 message (SRB1 message) for short.

PC5 interface

The wireless communication interface between Remote UE and relay UE. The remote UE and the relay UE communicate through a sidelink (sidelink), and the communication interface of the sidelink communication is the PC5 interface, so the descriptions of sidelink and PC5 in this article can be replaced with each other.

The PC5 RLC entity refers to the RLC entity used for PC5 interface communication. When the UE is connected to the base station through the relay UE, the PC5 RLC entity carries information from the Uu PDCP entity, so such a PC5 RLC entity can also be called a PC5 RLC bearer (bearer).

Uu interface

Wireless communication interface between UE and base station. UE can use E-UTRAN to communicate with eNB on Uu interface. UE can also use NR to communicate with gNB on Uu interface.

The Uu RLC entity refers to the RLC entity used for Uu interface communication.

In essence, both the PC5 RLC entity and the Uu RCL entity refer to the RLC entity that complies with the RLC protocol stack, but the communication interfaces used by the two are different.

Timer T304

In the prior art, when the UE receives the RRC connection reconfiguration message from the base station, when the message indicates that the UE performs reconfiguration with sync, or handover (handover/switch), the UE will start the timer T304 is used to manage the synchronization process. If the synchronous reconfiguration is successfully completed, the UE will stop T304; if the T304 runs overtime, it means that the synchronous reconfiguration process has failed, and the UE will trigger the RRC connection re-establishment process. During this process, the UE sends an RRC re-establishment request to the base station Message (RRCReestablishmentRequest message).

In this paper, T304 is taken as an example, but it is not limited to this timer, and may also be other timers for managing handover or synchronous reconfiguration.

Hereinafter, several embodiments of the present invention for the above-mentioned problems are described in detail.

Example 1

This embodiment provides a method performed by a user equipment UE, as shown in FIG. 3 , the method includes the following steps.

Step S301: The UE receives an RRC message from the base station, such as an RRC connection reconfiguration message, in which the UE is instructed to execute a reconfiguration with sync. Preferably, the UE is a remote UE before receiving the configuration message, it is connected to the relay UE, and has established an RRC connection with the base station through the relay UE, and is in an RRC connection state. And optionally, the reconfiguration message instructs the UE to switch from the current indirect connection via the relay to the direct connection via the cell, or instructs the remote UE to perform a path switch (path switch) to the target cell. Or, the message indicating synchronous reconfiguration does not contain the relevant configuration or information element (information element, IE) instructing the UE to perform path handover to the target relay UE, thus implicitly instructing the remote UE to handover to the target cell.

Step S302: When receiving the above reconfiguration message, the UE starts the timer T304, and optionally, starts synchronizing with the downlink of the target cell (start synchronizing to the DL of the target Cell).

Step S303: When T304 expires (T304expiry), the UE restores (revert back) the original configuration (ie the configuration used before receiving the above reconfiguration message), and starts the RRC connection re-establishment process.

The "original configuration" here may refer to the configuration of the UE in the source cell (source cell), or the configuration received by the UE under the indirect connection and from the base station side.

In order to avoid re-establishment failure, the original configuration restored by the UE does not include (excluding) the configuration related to PC5, such as the configuration of PC5 RLC bearer, or/and the configuration of PC5 MAC, or/and the configuration of PC5 physical layer wait. In other words, configurations related to relay operations are not included.

Another embodiment of the above scheme can be

When T304 runs overtime (T304 expiry), the UE judges whether it is directly connected or not directly connected before:

If the UE is in a direct connection (or the UE is not in an indirect connection), then the UE restores (revert back) the original configuration and starts the RRC connection re-establishment process;

If the UE is in a non-direct connection (or the UE is not in a direct connection), then the UE restores (revert back) the original configuration except the above-mentioned PC5-related configuration (or does not restore the above-mentioned PC5-related configuration), and starts RRC connection re-establishment process.

Here, "UE is not in direct connection" can be replaced by "UE is connected to relay UE", and "UE is not in direct connection" can be replaced by "UE is not connected to relay UE", because UE is either in direct connection or It is in an indirect connection, so it can be seen that if the UE is not in an indirect connection, then the UE is in a direct connection.

Example 2

The UE receives an RRC message from the base station, such as an RRC connection reconfiguration message, and the message is as described in Embodiment 1.

When receiving the above reconfiguration message, the UE starts the timer T304.

When T304 runs overtime (T304expiry), UE restores (revert back) the configuration used in the source cell (or restores the original configuration, that is, the configuration used before receiving the above reconfiguration message), and starts the RRC connection re-establishment process .

During the RRC connection re-establishment process, the UE can perform cell selection or relay selection. If the UE is not connected to the relay UE, or the UE is directly connected, it indicates that the UE has reselected a cell and reselected a suitable cell. Then the UE can release the existing or restored PC5-related configurations, such as releasing (release) PC5 RLC bearer, PC5 MAC entity, PC5 physical layer configuration, etc.; or discard (discard) the configuration associated with the sidelink relay operation, Or discard the configuration associated with sidelink communication (discard sidelink communication related configuration). Optionally, the UE can also establish or re-establish the Uu RLC entity for SRB1, and can also apply (apply) the default configuration for SRB1 (apply the default configuration for SRB1), and then restore SRB1 (resume SRB1), and reconnect the RRC connection The establishment request is submitted to the lower layer for transmission.

Another embodiment of the above scheme can be

During the RRC connection re-establishment process, the UE can perform cell selection or relay selection. If the UE is not connected to the relay UE, or the UE is directly connected, it indicates that the UE has performed cell selection and has selected a suitable cell (suitable cell). Then the UE further judges the reason for triggering RRC connection reestablishment. If the RRC connection re-establishment is triggered by T304 timeout, and this T304 is started when the UE switches from an indirect connection to a direct connection, then the UE releases the existing or configured PC5-related configuration, such as releasing (release) PC5 RLC bearer, PC5MAC entity, PC5 physical layer configuration, etc., or discard the configuration associated with the sidelink relay operation, or discard the configuration associated with the sidelink communication. Optionally, the UE can also establish or re-establish the Uu RLC entity for SRB1, and can also apply the default configuration of SRB1 (apply the default configuration for SRB1), then resume SRB1 (resume SRB1), and submit the RRC re-establishment request message to the lower layer for transmission.

As a supplement to the above solution, during the RRC connection re-establishment process, if the UE and the relay UE are connected through PC5 RRC, this indicates that the UE has selected a relay and has selected a suitable relay (suitable relay). Then the UE can apply the default configuration of SL-RLC for SRB1 (apply the default configuration of SL-RLC for SRB1), then resume SRB1 (resume SRB1), and submit the RRC re-establishment request message to the lower layer for transmission.

Fig. 4 is a brief structural block diagram of the user equipment UE involved in the present invention. As shown in FIG. 4 , the user equipment UE400 includes a processor 401 and a memory 402 . The processor 401 may include, for example, a microprocessor, a microcontroller, an embedded processor, and the like. The memory 402 may include, for example, a volatile memory (such as a random access memory RAM), a hard disk drive (HDD), a nonvolatile memory (such as a flash memory), or other memories. Memory 402 has program instructions stored thereon. When the instruction is executed by the processor 401, the above method described in detail in the present invention and executed by the user equipment may be executed.

The program running on the device according to the present invention may be a program that causes a computer to realize the functions of the embodiments of the present invention by controlling a central processing unit (CPU). The program or 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.

A program for realizing the functions of the various embodiments of the present invention can be recorded on a computer-readable recording medium. The corresponding functions can be realized by causing a computer system to read programs recorded on the recording medium and execute the programs. The so-called "computer system" here may be a computer system embedded in the device, which may include an operating system or hardware (such as peripheral devices). The "computer-readable recording medium" may be a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a recording medium in which a short-term dynamic storage program is stored, or any other recording medium readable by a computer.

Various features or functional modules of the devices used in the above-mentioned embodiments may be implemented or executed by circuits (for example, single-chip 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. A general-purpose processor can be a microprocessor, or it can be any existing processor, controller, microcontroller, or state machine. The above-mentioned circuits may be digital circuits or analog circuits. Where advances in semiconductor technology have resulted in new integrated circuit technologies that replace existing integrated circuits, one or more embodiments of the invention may also be implemented using these new integrated circuit technologies.

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

As above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific structure is not limited to the above embodiments, and the present invention also includes any design changes that do not deviate from the gist of the present invention. In addition, various changes can be made to the present invention within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention. In addition, components having the same effect described in the above embodiments can be substituted for each other.

Claims

A method performed by a user equipment is a method in which the user equipment UE establishes an RRC connection with the base station through a relay UE and thus is performed in an RRC connection state, including the following steps:

The UE receives an RRC connection reconfiguration message from the base station, and the reconfiguration message indicates that the UE performs synchronous reconfiguration;

When the UE receives the RRC connection reconfiguration message, it starts a timer T304 for managing handover or synchronous reconfiguration;

When the timer T304 expires, the UE restores the original configuration, that is, the configuration used before receiving the above-mentioned reconfiguration message, and starts the RRC connection re-establishment process, wherein the original configuration restored by the UE does not include the relevant configuration of PC5 .
The method performed by user equipment according to claim 1, wherein,

The above reconfiguration message instructs the UE to switch from an indirect connection via a relay to a direct connection via a cell.
The method performed by the user equipment according to claim 2, wherein,

The above original configuration is the configuration received by the UE from the base station side under the indirect connection via the relay.
The method performed by the user equipment according to claim 3, wherein,

When the timer T304 runs overtime, the UE judges whether it is in an indirect connection via a relay before,

If the UE is in the indirect connection via the relay, then the UE restores the original configuration except the related configuration of PC5 above, and starts the RRC connection re-establishment procedure.
The method performed by user equipment according to claim 1, wherein,

The foregoing reconfiguration message indicates information that the UE is synchronized to a cell.
The method performed by the user equipment according to claim 5, wherein,

The original configuration above is the configuration of the source cell.
The method performed by the user equipment according to claim 6, wherein,

When the timer T304 expires, the UE restores the configuration used in the source cell and starts the RRC connection re-establishment process.
The method performed by the user equipment according to claim 7, wherein,

During the RRC connection re-establishment process, if the UE is not connected to the relay UE, then the UE releases the existing configuration related to PC5.
The method performed by the user equipment according to claim 7, wherein,

During the RRC connection re-establishment process, if the UE is not connected to the relay UE, then the UE further determines the reason for triggering the RRC connection re-establishment.
A user equipment, comprising:

processor; and

a memory on which instructions are stored,

When the above-mentioned instructions are executed by the above-mentioned processor, the above-mentioned user equipment is caused to execute the method according to any one of claims 1-9.