CN116170898A

CN116170898A - Method executed by user equipment and user equipment

Info

Publication number: CN116170898A
Application number: CN202111417415.5A
Authority: CN
Inventors: 张崇铭; 刘仁茂
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2021-11-25
Filing date: 2021-11-25
Publication date: 2023-05-26
Also published as: WO2023093818A1

Abstract

The invention provides a method executed by user equipment and the user equipment, wherein the method is executed by the UE in an RRC connection state by establishing RRC connection between the relay UE and a base station, and comprises the following steps: the UE receiving an RRC connection reconfiguration message from the base station, the reconfiguration message indicating that the UE performs synchronous reconfiguration; when the UE receives the RRC connection reconfiguration message, a timer T304 for managing handover or synchronous reconfiguration is started; when the timer T304 runs out, the UE restores the original configuration, i.e., the configuration used before the above reconfiguration message is received, and starts an RRC connection reestablishment procedure, wherein the relevant configuration of the PC5 is not included in the original configuration restored by the UE.

Description

Method executed by user equipment and user equipment

Technical Field

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

Background

Within a cell covered by a base station, a user equipment UE may communicate directly with the base station, such a communication connection being referred to as a direct connection (direct connection). The UE may also be communicatively coupled to the base station via a relay UE, which may be referred to as an indirect connection (indirect connection). In the context of communication with a base station via a relay UE, this UE is referred to as a remote UE (remote UE).

In order to ensure continuity of communication traffic, a UE indirectly connected to a base station through a relay UE may perform handover (switch/handover) under the direction of the base station, thereby implementing a direct connection with the base station, and such handover may be referred to as handover from an indirect connection to a direct connection.

The UE may fail in performing the indirect connection to direct connection handover procedure, for example, the timer T304 managing the handover runs out, indicating the handover failure, and then the UE resumes the original configuration and performs the RRC connection re-establishment procedure. During the connection re-establishment procedure, the UE may perform cell reselection and relay reselection.

In one case, the UE experiencing the handover failure described above selects a cell to initiate an RRC connection re-establishment procedure. However, when the operation of the UE is time-out at T304, the original configuration is restored, and because the original configuration is adapted to the scenario that the UE is indirectly connected with the base station through the relay, when the UE reselects the cell and needs to be directly connected with the base station, the original configuration cannot be used, thereby causing the reconstruction failure. This is a problem to be solved.

Disclosure of Invention

In order to solve the above problems, the present invention provides a method performed by a user equipment and the user equipment capable of avoiding a reconstruction failure.

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

the UE receiving an RRC connection reconfiguration message from the base station, the reconfiguration message indicating that the UE performs synchronous reconfiguration;

when the UE receives the RRC connection reconfiguration message, a timer T304 for managing handover or synchronous reconfiguration is started;

when the timer T304 runs out, the UE restores the original configuration, i.e., the configuration used before the above reconfiguration message is received, and starts an RRC connection reestablishment procedure, wherein the relevant configuration of the PC5 is not included in the original configuration restored by the UE.

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

the reconfiguration message described above indicates that the UE switches from an indirect connection via the relay to a direct connection via the cell.

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

the original configuration is a configuration from the base station side that the UE receives via the indirect connection of the relay.

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

when the timer T304 runs out, the UE determines whether it was previously in an indirect connection via relay,

if the UE is in an indirect connection via relay, the UE resumes the original configuration except for the relevant configuration of the PC5 described above, and initiates an RRC connection re-establishment procedure.

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

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

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

the original configuration is the configuration of the source cell.

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

when the timer T304 runs out, the UE resumes the configuration of use in the source cell and starts an RRC connection re-establishment procedure.

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

during RRC connection re-establishment, if the UE is not connected to the relay UE, the UE releases the existing PC 5-related configuration.

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

in the RRC connection reestablishment process, if the UE is not connected to the relay UE, the UE further determines a reason for triggering RRC connection reestablishment.

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

a processor; and

a memory, the memory having instructions stored thereon,

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

According to the method executed by the user equipment and the corresponding user equipment, the reconstruction failure can be avoided.

Drawings

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

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

Fig. 3 is a diagram illustrating a method performed by a user equipment UE according to an embodiment of the present invention.

Fig. 4 is a schematic block diagram of a user equipment UE according to the present invention.

Detailed Description

The invention is described in detail below with reference to the drawings and the detailed description. 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 well-known techniques, which are not directly related to the present invention, are omitted to prevent confusion of the understanding of the present invention.

The following describes some terms related to the present invention, and specific meanings of the terms are found in the 3GPP latest standard specification.

RedCap: reduced capability decline in function

UE: user Equipment

NR: new Radio New generation wireless technology

MAC: medium Access Control multimedia access control

MAC CE: MAC control element MAC control element

RLC: radio Link Control radio 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 radio access network

Sidelink: side-link communication

SCI: sidelink Control Information side-uplink communication control information

AS: access Stratum, access Stratum

IE: information Element, information element

CE: control Element, control Element

MIB: master Information Block main information block

NR：New Radi _o New radio

SIB: system Information Block System information block

NG-RAN: NG Radio Access Network New generation radio Access network

DCI: downlink Control Information downlink control information

ADAPT: adaptation layer, side link communication Adaptation layer

PHY: physical layer

RB: radio bearer

DRB: data Radio Bearer radio bearer for data

SRB: signalling Radio Bearer signalling radio bearer

PDU: protocol Data Unit protocol data unit

SDU: service Data Unit service data unit

V2X: vehicle-to-Everyting Vehicle networking

CCCH: common Control Channel common control channel

DCCH: dedicated Control Channel proprietary control channel

In the present invention, the network, the base station and the RAN are used interchangeably, and the network may be a long term evolution LTE network, a New radio access technology (New RAT, NR) network, an enhanced long term evolution LTE network, or other networks defined in a later evolution version of 3 GPP.

In the present invention, the UE may refer to an NR device supporting an NR Sidelink relay function described in the background art, or may refer to an NR device supporting an NR Sidelink relay architecture, or may refer to other types of NR devices or LTE devices.

In the present invention, sidelink and PC5 may be used interchangeably, and RLC channel (channel), RLC entity and RLC bearer (bearer) may be used interchangeably. And PC5 is used herein for relay operations and thus may also be replaced by relay.

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

The PC5 interface is an interface for control plane and user plane sidlink communications between UEs. For Sidelink unicast, the PC5-RRC connection is an AS layer logical connection between a pair of source layer II IDs and a target layer II ID. One PC5 unicast link establishment corresponds to one PC5-RRC connection establishment.

The UE-to-Network relay is shown in fig. 1, in scenario 1 and scenario 2, the left side is the far-end UE, the middle is the relay UE, and the right side is the Network; in scenario 3, the two sides are networks, and the middle is from left to right a remote UE and a relay UE, respectively. The remote UE and the relay UE are connected through a PC5 interface, and the relay UE and the network are connected through a Uu interface. Because 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 remote UE and the network.

The scenario of the UE-to-Network relay includes:

1) Remote UE out of coverage, relay UE in coverage (scenario 1 shown in fig. 1);

2) Both Remote UE and Relay UE are in coverage and in the same cell (scenario 2 shown in fig. 1);

3) Both Remote UE and Relay UE are in coverage but in different cells (scenario 3 shown in fig. 1).

For the side-uplink communication layer two (L2) relay architecture, the control plane protocol stacks of the remote UE, relay UE and base station are shown in fig. 2.

After a relay UE is selected by the Remote UE to provide relay service for the Remote UE, PC5-RRC connection is established with the relay UE so as to communicate with the network through the relay UE. The Remote UE may 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 encapsulates data through Uu PDCP layer by performing air interface RRC connection establishment (setup), re-establishment (re-establishment), resume (resume) and other messages to the network, and then submits the encapsulated data to the PC5RLC entity for further encapsulation, and carries the encapsulated data on the PC5RLC channel, and submits the encapsulated data layer by layer downwards through the PC5-MAC and the PC 5-PHY. After receiving the data carrying the message, the relay UE submits the message upwards layer by layer through the PC5-PHY and the PC5-MAC, finds a Uu RLC channel carrying the message through the mapping relation between the PC5RLC channel and the Uu RLC channel, and encapsulates the message in the Uu message/data and sends the Uu message/data to the network. In turn, the RRC message replied by the network is sent to the relay UE by the base station encapsulating it in Uu message/data, the relay UE finds the PC5RLC channel carrying the message through the mapping relationship between the PC5RLC channel and Uu RLC channel, and the message is encapsulated in the PC5 message/data and sent to the remote UE. When Remote UE initiates processes such as RRC connection establishment, reestablishment, and recovery to the network, in order to correctly transmit data when needed and stop data transmission when not needed, uu RLC/MAC and PC5 RLC/MAC also need to perform corresponding processing. Conversely, the network can release and suspend the air interface RRC connection to the remote UE through the relay UE, and in these processes Uu RLC/MAC and PC5 RLC/MAC also need to perform corresponding processing.

SRB0 message

On the Uu interface, the UE sends an RRC connection establishment request message, an RRC connection reestablishment request message, and an RRC connection restoration request message to the base station through SRB 0. SRB0 is an RRC message (SRB 0 is forRRC messages using the CCCH logical channel) for carrying transmissions using a logical channel with a logical channel class CCCH. It can be seen that the RRC connection establishment request message, the RRC connection reestablishment request message, and the RRC connection restoration request message all belong to such RRC messages transmitted using a logical channel with a logical channel class CCCH. Herein, the RRC message transmitted on SRB0 may be simply referred to as an SRB0 message (SRB 0 message).

SRB1 message

On the Uu interface, the UE sends an RRC connection resume request message to the base station through SRB 0. As a response message, the base station may transmit an RRC connection restoration message to the UE through SRB 1. Or the UE sends an RRC reestablishment request message to the base station through SRB 0. As a response message, the base station may transmit an RRC reestablishment message to the UE through SRB 1. SRB1 is an RRC message (SRB 1 is for RRCmessages using the DCCH logical channel) for carrying transmissions using a logical channel with a logical channel class DCCH. It can be seen that the RRC connection restore message and the RRC connection reestablishment message all belong to such RRC messages transmitted using a logical channel of the logical channel class CCCH. Herein, the RRC message transmitted on SRB1 may be simply referred to as an SRB1 message (SRB 1 message).

PC5 interface

Wireless communication interface between Remote UE and relay UE. The Remote UE and the relay UE communicate through a sidelink (sidelink), and a communication interface of the sidelink is a PC5 interface, so that descriptions of the sidelink and the PC5 may be replaced in this document.

The PC5RLC entity refers to an RLC entity for PC5 interface communication. The PC5RLC entity carries information from the Uu PDCP entity when the UE connects with the base station through the relay UE, and thus such PC5RLC entity may also be referred to as a PC5RLC bearer (bearer).

Uu interface

Wireless communication interface between UE and base station. The UE may communicate with the eNB over the Uu interface using E-UTRAN. The UE may also employ NR and gNB communication over the Uu interface.

The Uu RLC entity refers to an RLC entity for Uu interface communication.

Both the PC5RLC entity and Uu RCL entity are in essence RLC entities compliant with the RLC protocol stack, except that the communication interfaces for both are different.

Timer T304

In the prior art, when the UE receives an RRC connection reconfiguration message from the base station, and the message instructs the UE to perform synchronization reconfiguration (reconfiguration with sync), or handover (handover/switch), the UE starts a timer T304 for managing the synchronization procedure. If the synchronization reconfiguration is completed successfully, the UE stops T304; if T304 runs out, meaning that the synchronization reconfiguration procedure fails, the UE triggers an RRC connection reestablishment procedure in which the UE sends an RRC reestablishment request message to the base station (RRCReestablishmentRequest message).

T304 is taken herein as an example, but is not limited to this timer, but may be other timers for managing a handover or for synchronizing a reconfiguration.

Several embodiments of the present invention for the above-described problems are described in detail below.

Example 1

The present embodiment provides a method performed by a user equipment UE, as shown in fig. 3, and the method includes the following steps.

Step S301: the UE receives an RRC message, e.g., an RRC connection reconfiguration message, from the base station, where the message instructs the UE to perform a synchronization reconfiguration (execute a reconfiguration with sync). Preferably, before receiving the configuration message, the UE is a remote UE, which is connected to the relay UE, and establishes an RRC connection with the base station through the relay UE, and is in an RRC connection state. And optionally, the reconfiguration message indicates that the UE is handed over from a current indirect connection via relay to a direct connection via a cell, or that the remote UE performs path switching (path switch) to the target cell. Or the message indicating the synchronous reconfiguration does not contain related configuration or information element (information element, IE) for indicating the UE to execute path switching to the target relay UE, thereby implicitly indicating the remote UE to switch to the target cell.

Step S302: upon receipt of the reconfiguration message, the UE starts a timer T304 and, optionally, starts downlink synchronization with the target cell (start synchronising to the DL ofthe target Cell).

Step S303: when T304 runs out (T304 expiration), the UE resumes (reverse back) the original configuration (i.e., the configuration used before the above reconfiguration message was received), and starts the RRC connection re-establishment procedure.

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

In order to avoid the reestablishment failure, in the original configuration recovered by the UE, the configuration related to the PC5, for example, the configuration of the PC5RLC bearer, or/and the configuration of the PC5 MAC, or/and the configuration of the physical layer of the PC5, etc. is not included. Or does not include a configuration related to a relay operation.

Yet another embodiment of the above scheme may be

When T304 runs out (T304 expiration), the UE determines whether it was previously in direct or indirect connection:

if the UE is in direct connection (or the UE is not in indirect connection), the UE resumes (reverse back) the original configuration and starts an RRC connection re-establishment procedure;

if the UE is not directly connected (or the UE is not directly connected), the UE resumes (reverse back) the original configuration (or does not resume the relevant configuration of the PC 5) except the relevant configuration of the PC5, and starts the RRC connection re-establishment procedure.

Here, "UE is in indirect connection" may be replaced by "UE is connected to relay UE" and "UE is not in indirect connection" may be replaced by "UE is not connected to relay UE" since UE is either in direct connection or in indirect connection, it is seen that if UE is not in indirect connection then UE is in direct connection.

Example 2

The UE receives an RRC message, e.g., an RRC connection reconfiguration message, from the base station, as described in embodiment 1.

Upon receiving the reconfiguration message, the UE starts a timer T304.

When T304 runs out (T304 expire), the UE resumes (reverse back) the configuration of use in the source cell (or resumes the original configuration, i.e. the configuration used before the reception of the reconfiguration message described above), and starts the RRC connection re-establishment procedure.

During RRC connection re-establishment, the UE may make cell selection or relay selection. If the UE is not connected to the relay UE, or the UE is directly connected, this indicates that the UE has performed a cell reselection and has reselected to the appropriate cell. The UE may release the already existing or restored PC5 related configuration such as release (release) of PC5RLC bearers, PC5 MAC entity, configuration of PC5 physical layer, etc.; either discarding (discard) the configuration associated with the sidelink relay operation or discarding the configuration associated with the sidelink communication (discard sidelink communication related configuration). Optionally, the UE may also establish or re-establish Uu RLC entity for SRB1, and may also apply (apply) default configuration of SRB1 (apply the default configuration for SRB 1), then resume SRB1 (resume SRB 1), and submit RRC connection re-establishment request to the lower layer for transmission.

Yet another embodiment of the above scheme may be

During RRC connection re-establishment, the UE may make cell selection or relay selection. If the UE is not connected to the relay UE, or the UE is directly connected, this indicates that the UE has performed cell selection and has selected a suitable cell (useable cell). The UE further determines the reason for triggering RRC connection reestablishment. If RRC connection reestablishment is triggered by a T304 timeout and the T304 is initiated when the UE switches from an indirect connection to a direct connection, the UE releases an already existing or configured PC5 related configuration, e.g. releases (release) a PC5RLC bearer, a PC5 MAC entity, a configuration of the PC5 physical layer, etc., either discarding a configuration associated with a sidelink relay operation or discarding a configuration associated with sidelink communication. Optionally, the UE may also establish or re-establish Uu RLC entity for SRB1, and may also apply default configuration of SRB1 (apply the default configuration for SRB 1), then resume SRB1 (resume SRB 1), and submit RRC reestablishment request message to the lower layer for transmission.

In addition to the above, if the UE and the relay UE are connected through PC5 RRC during RRC connection reestablishment, this indicates that the UE has performed relay selection and has selected the appropriate relay (suitable relay). The UE may apply a default configuration for the SL RLC of SRB1 (apply the default configuration of SL-RLC for SRB 1) and then resume SRB1 (resume SRB 1) and submit the RRC reestablishment request message to the lower layers for transmission.

Fig. 4 is a schematic block diagram of a user equipment UE according to the present invention. As shown in fig. 4, the user equipment UE400 comprises a processor 401 and a memory 402. The processor 401 may include, for example, a microprocessor, a microcontroller, an embedded processor, or the like. The memory 402 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. The memory 402 has stored thereon program instructions. Which, when executed by the processor 401, may perform the above-described method performed by the user equipment as described in detail herein.

The program running on the apparatus according to the present invention may be a program for causing 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 a volatile store such as a random access memory RAM, a Hard Disk Drive (HDD), a nonvolatile store such as a flash memory, or other memory system.

A program for realizing the functions of the embodiments of the present invention may 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 term "computer system" as used herein may be a computer system embedded in the device and may include an operating system or hardware (e.g., 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 program is stored dynamically at a short time, or any other recording medium readable by a computer.

The various features or functional modules of the apparatus used in the embodiments described above may be implemented or performed by circuitry (e.g., single-chip or multi-chip integrated circuits). Circuits designed to perform the functions described herein may include a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The circuit may be a digital circuit or an analog circuit. Where new integrated circuit technologies are presented as an alternative to existing integrated circuits due to advances in semiconductor technology, one or more embodiments of the present invention may also be implemented using these new integrated circuit technologies.

Furthermore, 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 devices installed indoors or outdoors may be used as terminal devices or communication devices such as AV devices, kitchen devices, cleaning devices, air conditioners, office devices, vending machines, and other home appliances, etc.

As above, the embodiments of the present invention have been described in detail with reference to the accompanying drawings. However, the specific structure is not limited to the above-described embodiment, and the present invention also includes any design modification without departing from the gist of the present invention. In addition, various modifications can be made to the present invention within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in the different embodiments are also included in the technical scope of the present invention. Further, the components having the same effects described in the above embodiments may be replaced with each other.

Claims

1. A method performed by a user equipment, which is a method performed by the user equipment UE in an RRC connected state by establishing an RRC connection with a base station through a relay UE, comprising the steps of:

2. The method performed by a user equipment according to claim 1, wherein,

3. The method performed by the user equipment of claim 2, wherein,

4. The method performed by a user equipment of claim 3, wherein,

5. The method performed by a user equipment according to claim 1, wherein,

6. The method performed by the user equipment of claim 5, wherein,

the original configuration is the configuration of the source cell.

7. The method performed by the user equipment of claim 6, wherein,

8. The method performed by the user equipment of claim 7, wherein,

9. The method performed by the user equipment of claim 7, wherein,

10. A user equipment, comprising:

a processor; and

a memory, the memory having instructions stored thereon,

the instructions, when executed by the processor, cause the user equipment to perform the method according to any of claims 1-9.