WO2024051740A1

WO2024051740A1 - Method executed by user equipment and user equipment

Info

Publication number: WO2024051740A1
Application number: PCT/CN2023/117242
Authority: WO
Inventors: 张崇铭; 刘仁茂
Original assignee: 夏普株式会社; 张崇铭
Priority date: 2022-09-09
Filing date: 2023-09-06
Publication date: 2024-03-14
Also published as: CN117729600A

Abstract

The present disclosure provides a method executed by a user equipment (UE) and the UE. The method executed by the UE comprises: the UE receives a handover command instructing to execute a cell handover operation, the handover command comprising a sequence number or identification information of a target cell, and carrying indication information indicating whether an MAC layer needs to be reset; a lower layer of the UE indicates the information of the target cell to an RRC layer, and indicates whether the MAC layer needs to be reset; and the RRC layer of the UE uses configuration information corresponding to the target cell, and when the MAC layer needs to be reset, instructs to execute a reset operation of an MAC entity to the MAC layer. Therefore, when the cell handover operation is executed, the handover time delay can be shortened, and normal working of the target cell after the handover can be ensured, such that the communication efficiency and quality can be improved.

Description

Methods executed by user equipment and user equipment

Technical field

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

Background technique

When a UE in the RRC connected state moves from the coverage area of one cell to the coverage area of another cell, in order to ensure the continuity of service, the base station or the network side usually instructs the UE to perform a cell switch (Cell Switch/Cell Handover) operation. Handover in the prior art is triggered by RRC signaling, that is, when the UE receives the RRC reconfiguration message carrying the synchronization identifier (herein referred to as the layer 3 handover command), it will synchronize to the target specified in the message. community. The time from receiving the layer 3 handover command to completing synchronization with the target cell is called the handover delay. Since the UE needs to reset the MAC layer during this process, the service may be temporarily interrupted, thereby increasing the handover delay.

The base station or the network side can instruct the UE in the handover command that it does not need to reset the MAC layer during the cell handover process, thereby shortening the handover delay. However, if the target cell carried in the handover command is the current serving cell, if the MAC layer is not reset, the data in the HARQ cache in the cell will not be cleared, thus hindering the normal operation of the cell after the handover. So this problem needs to be solved.

Contents of the invention

The purpose of this disclosure is to propose a method executed by user equipment and corresponding user equipment to solve at least some of the above problems, so as to shorten the handover delay while ensuring the normal operation of the target cell after handover, thereby improving Efficiency and quality of communication.

According to an aspect of the present disclosure, a method performed by user equipment UE is provided, including: the UE receives a handover command indicating to perform a cell handover operation, the handover command includes the sequence number or identification information of the target cell, and carries an indication whether it is necessary Instructions to perform MAC layer reset; The lower layer of the UE indicates the information of the target cell to the RRC layer, and indicates whether a MAC layer reset needs to be performed; and the RRC layer of the UE applies the configuration information corresponding to the target cell, and when a MAC layer reset needs to be performed Next, instruct the MAC layer to perform a reset operation of the MAC entity.

According to another aspect of the present disclosure, a user equipment is provided, including: a processor; and a memory storing instructions; wherein the instructions perform the above method when executed by the processor.

Invention effect

According to the method executed by the user equipment and the user equipment of the present disclosure, when performing a cell handover operation, the handover delay can be shortened while ensuring the normal operation of the target cell after the handover, thereby improving the efficiency and quality of communication.

Description of the drawings

The above and other features of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a flowchart illustrating a method performed by a user equipment according to an embodiment of the present disclosure.

Figure 2 is a block diagram illustrating user equipment according to an embodiment of the present disclosure.

It is noted that the drawings are not necessarily to scale, emphasis being placed on illustrating the principles of the technology disclosed herein. Additionally, for purposes of clarity, similar reference numbers will be used throughout the drawings to refer to similar elements.

Detailed ways

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

Before the detailed description, several terms mentioned in this disclosure will be explained as follows. Unless otherwise indicated, terms referred to in this disclosure have the following meanings.
UE User Equipment User Equipment
RLF Radio Link FailureRadio link failure
NR New Radio new generation wireless technology
LTE Long Term Evolution long-term evolution technology
Elte Enhanced Long Term Evolution enhanced long term evolution technology
RRC Radio Resource Controlradio resource control
PDCP Packet Data Convergence Protocol Packet data convergence protocol (layer)
RLC Radio Link Control, wireless link control (layer)
MAC Medium Access Control media access control (layer)
PHY physical layerphysical layer
MAC CE Medium Access Control Control Element media access control layer control element
PDU Protocol Data UnitProtocol Data Unit
UE User Equipment User Equipment
NR New Radio new generation wireless technology
HARQ Hybrid Automatic Repeat reQuest
DCI Downlink Control InformationDownlink control information

MAC entity

The MAC layer has at least one MAC entity, and each MAC entity corresponds to a cell group (Cells Group, CG). Each MAC entity can be configured with one or more serving cells, and each serving cell corresponds to a carrier. The MAC layer can allocate a HARQ entity to each carrier (or each serving cell) to manage transmission on the carrier. Each HARQ entity maintains a set of uplink HARQ processes (HARQ processes) and a set of downlink HARQ process.

Pcell (Primary Cell) and Scell (Secondary Cell)

A UE in RRC connected state may have one or more serving cells, including at least one Pcell, and the serving cells other than Pcell may be Scell. After receiving the handover command, the UE will switch from the source Pcell to the target Pcell. The source Pcell refers to the Pcell that serves the UE before or when the UE receives the handover command, and the target Pcell refers to the cell in which the handover command indicates that the UE will synchronize, and the cell will perform New Pcell for UE. While switching Pcell, Scell can also be switched. The switching of Scell can include the addition of Scell, the change of Scell, and the release of Scell.

For example, before receiving the handover command, the UE has only one serving cell, namely Pcell-1. Then after receiving and executing the handover command, the UE can have several serving cells, including the target Pcell-2, and the newly added Scell ( s), these Scells can also be called target Scells.

For another example, before receiving the handover command, the UE is configured with a Scell-1 in addition to Pcell-1. Then after receiving the handover command and executing it, in addition to Pcell changing and becoming Pcell-2, Scell can also From Scell-1 to Scell-2, then Scell-2 is the target Scell of the UE, and Scell-1 is released.

For another example, before receiving the handover command, the UE is configured with a Scell-1 in addition to the Pcell. Then after receiving the handover command and executing it, in addition to the Pcell change, the Scell can also change from Scell-1 to Scell- 2, and a new Scell-3 is added, then Scell-2 and Scell-3 are both the target Scells of the UE, and Scell-1 is released.

In this article, the terms related, corresponding, corresponding, etc. can be replaced with each other.

In this article, the two terms of resetting the MAC entity and resetting the MAC layer can be interchanged.

In this article, the handover command refers to a message or instruction that instructs the UE to perform cell change/switch. It can be a message, MAC CE or DCI used to instruct the UE to perform cell change/switch. It can also carry a message that instructs the UE to perform cell change/switch. Cell change information message, MAC CE or DCI.

Since the UE needs to perform uplink or downlink synchronization (sync) operation on the target cell when performing cell change, in this article, "cell change" can also be replaced by "cell synchronization", that is, the handover command can be to instruct the UE A message or instruction to synchronize the target cell.

As shown in Figure 1, the method performed by user equipment UE includes steps 101, 103, and 105.

In step 101, the UE receives a switching command instructing to perform a cell switching operation. The switching command includes the sequence number or identification information of the target cell, and carries indication information indicating whether a MAC layer reset needs to be performed.

In step 103, the lower layer of the UE indicates the information of the target cell to the RRC layer and indicates whether a MAC layer reset needs to be performed.

In step 105, the RRC layer of the UE applies the configuration information corresponding to the target cell, and if a MAC layer reset needs to be performed, instructs the MAC layer to perform a reset operation of the MAC entity.

According to the above method, since the handover command carries indication information indicating whether a MAC layer reset needs to be performed, it can be determined based on the indication information whether to perform a MAC layer reset. Therefore, when performing a cell handover operation, it is possible to shorten the The handover delay also ensures the normal operation of the target cell after the handover, thereby improving the efficiency and quality of communication.

Below, the method executed by user equipment of the present disclosure will be described with reference to embodiments.

Example 1

Step 1: The UE receives the switch command (Switch Command/Handover Command). The handover command indicates the information of the target cell, for example, the sequence number (index) or identification (identity) of the target cell configuration information, or the identification information corresponding to the target cell configuration, and optionally, in the handover command It may also carry indication information on whether a MAC layer reset (or a reset operation on the MAC entity) needs to be performed.

Preferably, the target cell in the handover command refers to the target Pcell, that is, the Pcell changed by the UE after executing the handover command. The configuration information of the target cell may also contain information of one or more Scells. This or these Scells may be called target Scells. The information of the target Scell is not carried directly in the handover command, but is determined by determining the target Pcell. Determine the target Scell included in the target Pcell configuration information.

In one case, the switching command carries explicit indication information indicating whether the MAC layer needs to be reset when executing the switching command or after receiving the switching command;

Such explicit instructions can be achieved by:

Set a field (field) or information element (IE, Information Element) in the switching command, which can be named MAC reset. When this field (or IE) is set to 1 in the handover command received by the UE, it indicates that the MAC layer needs to be reset, that is, the MAC is reset;

When this field is set to 0 in the handover command received by the UE, it indicates that there is no need to reset the MAC layer.

In another case, the switching command carries an implicit instruction indicating that when executing the When switching commands, is it necessary to reset the MAC layer?

Such implicit instructions can be achieved by:

When the field (or the IE) does not exist in the handover command received by the UE, it means that there is no need to reset the MAC layer.

Different DCI formats can also be used to represent switching commands indicating that MAC reset is required and switching commands that do not require MAC reset. For example, handover commands are transmitted in the form of DCI. Both DCI format-1 and DCI format-2 can be used for handover commands: when the UE receives a handover command using DCI format-1, the MAC layer needs to be reset. , that is, resetting the MAC; when the UE receives a handover command using DCI format-2, there is no need to reset the MAC layer, that is, the MAC is not reset.

Handover commands can also be transmitted in the form of MAC CE. The above-mentioned MAC Reset field (or information element) can be carried in the MAC CE used for handover or in the DCI.

Step 2: The lower layer of the UE, such as the PHY or MAC layer, indicates to the RRC layer that the above handover command is received, and preferably, indicates the information of the target cell to the RRC layer.

Based on the above indication information, the RRC layer applies the configuration information corresponding to the target cell. Such configuration information may be configuration information that the UE has received from the base station or the network side and stored on the UE side before receiving the above handover command. Preferably, such configuration information should also be valid or within the validity period. If the corresponding configuration information is invalid when receiving the handover command, the UE can ignore the handover command, that is, not perform any operation. Or start the RRC Connection Reestablishment procedure (RRC Connection Reestablishment procedure) after judging that the configuration information is invalid.

In addition, the PHY or MAC layer can also indicate to the RRC layer whether the MAC needs to be reset.

If the RRC layer is instructed to perform a MAC layer reset, the RRC layer instructs the MAC layer to reset the MAC entity (MAC reset);

If the RRC layer is not instructed to perform a MAC layer reset, the RRC does not perform the above operations.

Another possible implementation may be that when the MAC layer receives the above switching command, if the switching command indicates that the MAC needs to be reset, the MAC layer may directly execute the MAC The reset operation does not need to be notified to the RRC layer.

Step 3: According to the configuration information of the target cell, the RRC layer can make the following judgment, and when the following situation is true, or one or more of the following situations exist, the RRC layer can instruct the associated MAC entity to target the corresponding or The associated or related serving cell performs a partial reset operation:

Case 1: If the target Pcell is an Scell in the current serving cell (in this case, the UE has at least two current serving cells, one of which is Pcell, and the other one or more serving cells can be Scell( s)), that is, the target Pcell and an Scell in the current serving cell are the same cell, or

Case 2: If the target Scell is a Pcell in the current serving cell (in this case, the UE can have only one current serving cell, that is, the current Pcell, or there can be multiple ones, one of which is the current Pcell, and the others One or more serving cells are Scell(s)), that is, the target Scell and the Pcell in the current serving cell are the same cell.

Here, the "associated serving cell" refers to the target Pcell or the current Scell that is the same as the target Pcell in case 1. They are the same cell; in case 2, it refers to the target Scell or the current Pcell, which are the same cell. A neighborhood.

The RRC layer of the UE can determine whether it is the same cell based on the physical cell identity (PCID) of the cell. For example, in case 1, if the PCID of the target Pcell is the same as the PCID of an Scell in the current serving cell, then they are the same cell. For another example, in case 2, the target Scell and the current Pcell have the same PCID, then they are the same cell. The UE can also use other methods to determine whether two cells are the same cell.

Preferably, if the RRC layer is instructed to perform a MAC layer reset in step two, or the MAC layer autonomously performs a MAC layer reset operation, then the UE does not need to perform step three. If the RRC layer is not instructed to perform a MAC layer reset in step two, or the MAC layer does not autonomously perform a MAC layer reset operation, then the UE performs step three.

Example 2

Based on Embodiment 1, the operation of the MAC layer to perform partial reset on the relevant cells may include one or more of the following operations:

Set the NDI value of the upstream HARQ process (HARQ process) to 0. Preferably, It is all uplink HARQ processes (HARQ processes) associated with the cell;

Flush the uplink HARQ buffer (HARQ buffer), preferably all uplink HARQ buffers of the associated cell;

Refresh the cache (buffer) of the downlink HARQ process, preferably the buffers of all downlink HARQ processes associated with the cell;

For each downlink HARQ process, the next received transmission is considered to be the first transmission of the chansport block (TB);

Stop the ongoing random access process;

Stop transmission on the PUCCH of the cell;

Stop transmission on the configured Uplink Grant of the cell.

Example 3

Based on Embodiment 1, the reset operation of the MAC entity may include one or more of the following operations:

Initialize the transmission variables of the logical channel and set the values of these variables to zero. These variables are used in the logical channel prioritization process;

Set the NDI value of all upstream HARQ processes (HARQ process) to 0;

Refresh the cache (buffer) of all downstream HARQ processes;

Refresh message three cache;

Refresh message A cache;

Stop the random access process;

Cancel the triggered Scheduling Request procedure;

Cancel the triggered Buffer Status Reporting procedure (Buffer Status Reporting procedure);

Stop all running timers.

Example 4

The switching command in step 2 in the foregoing embodiment can also be implemented in the following manner.

The handover command can be received by the UE at the PHY layer, for example, the handover command is indicated to the UE in the form of DCI. In this case, it can be considered that there is no need to perform a reset of the MAC layer; the handover command can also be received at the MAC layer. to, for example, via MAC CE A handover command is indicated to the UE, then in this case it can be considered that a reset of the MAC layer always needs to be performed.

Preferably, depending on the form of the received handover command, the PHY or MAC layer may further indicate to the RRC layer whether the MAC needs to be reset. For example, if the handover command received by the UE is a handover command in the form of DCI, then the PHY layer of the UE can indicate the target cell information to the upper layer (such as the RRC layer); for another example, the handover command received by the UE is in the form of MAC CE. command, then in addition to indicating the target cell information to the upper layer, the MAC layer of the UE can also indicate the need to perform a MAC layer reset operation.

In addition, when receiving a MAC CE-based handover command, the MAC layer indicates the target cell information to the upper layer and the MAC layer can directly perform the MAC reset operation independently without the need to indicate to the upper layer.

Example 5

Based on the foregoing embodiments, the handover command may further indicate which target cell(s) (target Pcell or target Scell) needs to be partially reconfigured.

For example, a field can be set in the MAC CE or DCI used to carry handover commands, named the partial reset field. The value of this field can be one or several cell identifiers, or a cell number.

For the cell corresponding to the value of this field, the UE performs a partial reset operation. Specifically, the lower layer of the UE may indicate to the RRC layer the corresponding cell identifier in the value of this field, and the RRC layer may instruct the MAC layer/MAC entity to perform partial reset operations on these cells based on the indication; it may also be that after receiving the user After the handover of MAC CE or DCI, the MAC layer performs a partial reset operation on the corresponding cell in the field value.

Preferably, when the value of this field is not empty, the UE performs a partial reset operation on the cell corresponding to the value of this field; when the value of this field is empty, or the field is not carried in the MAC CE or DCI, the UE can The MAC entity is reset according to the method in Embodiment 1, or no reset operation is performed.

You can also set a field in the above MAC CE or DCI, including two bits,

When the value of this field is 00, it means that there is no need to reset the MAC entity;

When the value of this field is 11, it indicates that the MAC entity needs to be reset;

When the value of this field is 01 or 10, it means partial reset; preferably, partial reset The relevant cell is indicated by the aforementioned partial reset field.

Or when the value of this field is 01, it means partial reset of the current Pcell;

When the value of this field is 10, it means partial reset of the current Scell.

Another implementation method of the above solution can also be:

Set a field in the above MAC CE or DCI, including one bit,

When the value of this field is 0, it means that there is no need to reset the MAC entity;

When the value of this field is 1, it indicates that a partial reset is performed; preferably, the relevant cells of the partial reset are indicated by the aforementioned partial reset field.

When this field does not exist, it means that the MAC entity always needs to be reset.

This solution can also be applied to DCI formats. For example, DCI format-2 can always include this field, but DCI format-1 does not include this field.

This embodiment can also be used alone to indicate partial reset and MAC reset information to the UE.

Figure 2 is a block diagram illustrating user equipment 20 according to one embodiment of the present disclosure. As shown in Figure 2, the user equipment 20 includes a processor 201 and a memory 202. The processor 201 may include, for example, a microprocessor, a microcontroller, an embedded processor, or the like. The memory 202 may include, for example, volatile memory (such as random access memory RAM), hard disk drive (HDD), non-volatile memory (such as flash memory), or other memory. Memory 202 stores program instructions. When executed by the processor 201, the instructions may perform the above-mentioned method performed by the user equipment described in detail in this disclosure (for example, the method shown in FIG. 1).

The program running on the device according to the present disclosure may be a program that causes the computer to implement the functions of the embodiments of the present disclosure 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.

Programs for realizing the functions of each embodiment of the present disclosure may be recorded on a computer-readable recording medium. Corresponding functions can be realized by causing the computer system to read programs recorded on the recording medium and execute these 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). "Computer readable "Recording medium" may be a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a recording medium for short-term dynamic storage of programs, or any other recording medium readable by a computer.

Various features or functional modules of the devices used in the above-described embodiments may be implemented or performed by circuits (eg, single-chip or multi-chip integrated circuits). Circuitry designed to perform the functions described in this specification 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 devices, discrete gate or transistor logic, discrete hardware components, or any combination of the above. A general-purpose processor can be a microprocessor or any existing processor, controller, microcontroller, or state machine. The above circuit may be a digital circuit or an analog circuit. When new integrated circuit technologies emerge to replace existing integrated circuits due to advances in semiconductor technology, one or more embodiments of the present disclosure may also be implemented using these new integrated circuit technologies.

Furthermore, the present disclosure is not limited to the above-described embodiment. Although various examples of the embodiments have been described, the disclosure is not limited thereto. Fixed or non-mobile electronic devices installed indoors or outdoors can be used as UE devices or communication devices, 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 disclosure 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 disclosure also includes any design changes that do not deviate from the gist of the present disclosure. In addition, various modifications can be made to the present disclosure within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, components having the same effect described in the above embodiments may be substituted for each other.

Claims

A method performed by user equipment UE, including:

The UE receives a handover command instructing to perform a cell handover operation. The handover command contains the sequence number or identification information of the target cell, and carries indication information indicating whether a MAC layer reset needs to be performed;

The lower layer of the UE indicates the information of the target cell to the RRC layer and indicates whether a MAC layer reset needs to be performed; and

The RRC layer of the UE applies the configuration information corresponding to the target cell, and if a MAC layer reset needs to be performed, instructs the MAC layer to perform a reset operation of the MAC entity.
The method of claim 1, wherein,

The indication information indicates whether a MAC layer reset needs to be performed through an explicit indication, an implicit indication, or a different DCI format carried in the switching command.
The method of claim 1, wherein,

When the UE receives the handover command, if the indication information indicates that a MAC layer reset needs to be performed, the MAC layer directly performs the MAC layer reset operation without instructing the RRC layer.
The method of claim 1, wherein,

When at least one of the following conditions exists, the RRC layer instructs the MAC layer to perform a partial reset operation on the relevant cell:

The target Pcell is an Scell in the current serving cell;

The target Scell is the Pcell in the current serving cell.
The method of claim 4, wherein,

The operation of the MAC layer to perform partial reset on the relevant cell includes at least one of the following operations:

Set the NDI value of the upstream HARQ process to 0;

Refresh the upstream HARQ cache;

Refresh the cache of the downstream HARQ process;

For each downlink HARQ process, the next received transmission is considered to be the first transmission of the transmission block;

Stop the ongoing random access process;

Stop transmission on the PUCCH of the cell;

Stop transmission on the configured uplink grant for this cell.
The method of claim 1, wherein,

The reset operation of the MAC entity includes at least one of the following operations:

Initialize the transmission variable of the logical channel and set its value to 0;

Set the NDI value of all upstream HARQ processes to 0;

Refresh the cache of all downstream HARQ processes;

Refresh message three cache;

Refresh message A cache;

Stop the random access process;

Cancel the triggered scheduling request process;

Cancel the triggered cache status reporting process;

Stop all running timers.
The method of claim 1, wherein,

When the UE receives the handover command in the form of DCI at the PHY layer, the PHY layer indicates the information of the target cell to the upper layer.
The method of claim 1, wherein,

When the UE receives the handover command in the form of MAC CE at the MAC layer, the MAC layer indicates the information of the target cell to the upper layer and indicates that a MAC layer reset needs to be performed.
The method of claim 1, wherein,

In the handover command, the target cell that needs to be partially reset is indicated.
A user device including:

processor; and

Memory, which stores instructions;

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