WO2022022444A1

WO2022022444A1 - Method executed by user equipment, and user equipment

Info

Publication number: WO2022022444A1
Application number: PCT/CN2021/108359
Authority: WO
Inventors: 常宁娟; 刘仁茂
Original assignee: 夏普株式会社; 常宁娟
Priority date: 2020-07-30
Filing date: 2021-07-26
Publication date: 2022-02-03
Also published as: CN114071783A

Abstract

The present invention provides a method executed by a user equipment (UE), comprising: when initiating a random access procedure for small data transmission (SDT), determining a random access channel (RACH) resource configured by a UE; and determining, according to the RACH resource configured by the UE, whether to send small data by performing a two-step random access procedure or by performing a four-step random access procedure.

Description

Method performed by user equipment and user equipment

technical field

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

Background technique

3rd Generation Partnership Project (3GPP) RAN#86 plenary meeting approved a new research project of version 17 (see non-patent literature: RP-193252: Work Item on NR smalldata transmissions in INACTIVE state), Referred to as the Small Data Transfer Project. The purpose of this research project is to optimize the signaling overhead and power consumption caused by small-sized data services that are not frequently sent by users. For user equipment (User Equipment, UE) in the radio resource control inactive state (Radio Resource Control_Inactive, RRC_Inactive), some infrequent small-sized data services (such as instant information, heartbeat signals to keep online, smart wearable devices or sensors) The transmission of periodic information and periodic meter reading services brought by smart metering equipment, etc.) makes the UE need to enter the RRC_connected state to perform the transmission of small-sized data packets, and the resulting signaling overhead brings about a decrease in network performance. It also greatly reduces the energy consumption of the UE. In the above-mentioned new research projects, it is mainly adopted to carry small-sized data in the random access process (such as accompanying or included in the message 3 of the four-step random access process to carry small data or accompanying or included in the two-step random access process). The message A in the process carries small data) without entering the RRC_connected state to obtain the means of uplink transmission resources to achieve the purpose, reducing signaling overhead and UE energy consumption.

In the next-generation wireless access (New Radio Access) system of version 16, the delay of the random access process (Random Access, RA) is shortened, and a two-step random access process is introduced, that is, the random access process that can be completed in two steps is introduced. into the process. When the Medium Access Control (MAC) layer of the UE initiates a random access control, the UE determines the random access control according to the resources used in the random access process, the reason for triggering the random access process, and the quality of the downlink channel. The random access type of the access procedure, that is, whether to use a two-step random access procedure or a four-step random access procedure. After the random access procedure type is determined, the UE performs the random access procedure using the resource and parameter configuration corresponding to the selected random access procedure type.

The present disclosure proposes a solution to the problem of how to set the random access procedure type in the random access procedure under the small data transmission mechanism used by the UE in the RRC_Inactive state.

SUMMARY OF THE INVENTION

In order to solve at least part of the above problems, the present invention provides a method performed by a user equipment and the user equipment, which can effectively perform a random access procedure of a UE in an inactive state when performing small-size data transmission.

According to the present invention, a method performed by a user equipment UE is proposed, comprising: when a random access procedure for small data transmission SDT is initiated, determining a random access channel RACH resource configured by the UE; The UE is configured with the RACH resources to determine whether to send small data by performing a two-step random access procedure or by performing a four-step random access procedure.

Preferably, if only the RACH resource for the two-step random access procedure of the SDT is configured on the bandwidth part for performing random access, the UE determines to send the small data by performing the two-step random access procedure. data, if only the RACH resource for the four-step random access procedure of the SDT is configured on the bandwidth part for performing random access, the UE determines to send small data by performing the four-step random access procedure , if both the RACH resources used for the four-step random access process of the SDT and the RACH resources used for the two-step random access process of the SDT are configured on the bandwidth part for performing random access, when the downlink When the RSRP of the reference signal received power of the loss reference is higher than the second RSRP threshold, the UE determines to send small data by performing the two-step random access procedure, and when the RSRP of the downlink path loss reference is lower than or not higher than the second RSRP threshold When the RSRP threshold is two, the UE determines to send small data by performing the four-step random access procedure.

Preferably, if only the RACH resource for the two-step random access procedure of the SDT is configured on the bandwidth part for performing random access, the UE determines to send the small data by performing the two-step random access procedure. data, when the UE further determines that the RSRP measurement value of the reference signal received power referenced by the downlink path loss is not higher than the second RSRP threshold value, the UE falls back to the execution of the non-SDT random access procedure. When the UE further determines that the RSRP measurement value referenced by the downlink path loss is higher than the second RSRP threshold, the UE continues to perform the two-step random access procedure for the SDT.

Preferably, if the RACH resource for the two-step random access procedure of the SDT is configured on the part of the bandwidth for performing random access, when the UE further determines that the medium access control protocol containing small data to be sent When the size of the data unit, that is, the MAC PDU, is larger than the first transport block size TBS threshold, the UE determines to send small data by performing the two-step random access procedure, and falls back to the non-SDT random access procedure. implement.

Preferably, if the RACH resource for the two-step random access procedure of the SDT is configured on the part of the bandwidth for performing random access, when the UE further determines that the medium access control protocol containing small data to be sent When the size of the data unit, that is, the MAC PDU, is greater than the first transport block size TBS threshold, if the RACH resource for the four-step random access process of the SDT is configured on the bandwidth part for performing random access, the The UE determines to send small data by performing the four-step random access procedure.

Preferably, if the RACH resource for the four-step random access process of the SDT is configured on the bandwidth part for performing random access, when the UE further determines that the medium access control protocol containing small data to be sent When the size of the data unit, that is, the MAC PDU, is larger than the TBS threshold value of the second transport block size, the UE falls back to the execution of the non-SDT random access procedure to select the random access type.

In addition, according to the present invention, a method performed by a user equipment UE is also proposed, comprising: in a two-step random access process for small data transmission SDT, the UE determines whether the number of times of sending a random access preamble exceeds If the UE determines that the number of times the random access preamble is sent exceeds the specified threshold, the UE is not configured with the random access channel RACH resource used for the four-step random access procedure of the SDT. , the UE falls back to the execution of the non-SDT four-step random access procedure.

In addition, according to the present invention, a method performed by a user equipment UE is also proposed, including: in a two-step random access process for small data transmission SDT, the UE determines whether the number of times of sending a random access preamble exceeds If the UE determines that the number of times the random access preamble is sent exceeds the specified threshold, the UE is not configured with the random access channel RACH resource used for the four-step random access procedure of the SDT. , the UE falls back to the execution of the non-SDT two-step random access procedure.

Preferably, when the UE is configured with RACH resources for the four-step random access procedure of the SDT, the UE determines to transmit small data by performing the four-step random access procedure.

In addition, according to the present invention, a user equipment is proposed, comprising: a processor; and a memory storing instructions; wherein the instructions execute the above method when executed by the processor.

According to the present invention, the random access procedure of the UE in the inactive state can be efficiently performed when small-sized data transmission is performed.

Description of drawings

FIG. 1 is a schematic sequence diagram of a contention-based four-step random access procedure.

FIG. 2 is a schematic sequence diagram of a non-contention-based four-step random access procedure.

FIG. 3 is a schematic sequence diagram of a contention-based two-step random access procedure.

FIG. 4 is a schematic sequence diagram of a non-contention-based two-step random access procedure.

FIG. 5 is a flowchart illustrating a method performed by a user equipment according to Embodiment 1 of the present invention.

FIG. 6 is a flowchart illustrating a method performed by a user equipment according to Embodiment 4 of the present invention.

FIG. 7 is a flowchart illustrating a method performed by a user equipment according to Embodiment 5 of the present invention.

FIG. 8 is a block diagram showing a user equipment UE according to the present invention.

detailed description

Other aspects, advantages and salient features of the present disclosure will become apparent to those skilled in the art from the following detailed description of exemplary embodiments of the present disclosure, taken in conjunction with the accompanying drawings. In the drawings, the same or similar structures are identified with the same or similar reference numerals.

In this disclosure, the terms "including" and "containing" and their derivatives are meant to include rather than limit; the term "or" is inclusive, meaning and/or.

In this specification, the various embodiments described below to describe the principles of the present disclosure are illustrative only and should not be construed in any way to limit the scope of the disclosure. The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the present disclosure as defined by the claims and their equivalents. The following description includes numerous specific details to assist in that understanding, but these details should be considered as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the present disclosure. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. Furthermore, the same reference numerals are used for similar functions and operations throughout the drawings.

Hereinafter, the NR mobile communication system is used as an example application environment to specifically describe various embodiments according to the present disclosure. However, it should be noted that the present disclosure is not limited to the following embodiments, but is applicable to more other wireless communication systems.

The following first describes some concepts involved in the present disclosure. It is worth noting that some of the nomenclature in the following description are merely illustrative, not restrictive, and other nomenclature may also be made.

RRC state: Three RRC states are defined in the NR system: RRC idle state RRC_IDLE, RRC inactive state RRC_INACTIVE and RRC connected state RRC_CONNECTED. RRC_IDLE refers to the state when the UE has not established an RRC connection, RRC_INACTIVE refers to the state when the UE has established an RRC connection but the RRC connection is suspended/suspended, and RRC_CONNECTED refers to the state when the UE has established an RRC connection and the RRC connection is not suspended. In the RRC_INACTIVE state, the UE saves the UE Inactive AS context, monitors the radio access network-based paging or core network-based paging, and monitors the Paging-Radio Network Temparary Identifier, P-RNTI) addresses short messages (short messages) sent through Downlink Control Information (DCI) to notify paging and system information updates, obtain system information through broadcast, and perform periodic Radio access network-based Notification Area (RNA) update or perform RNA update when moving out of a configured RNA. Currently, the UE in RRC_INACTIVE cannot realize unicast data communication with the network side, and it restores the RRC connection with the network side by sending an RRC resume request message to perform an RRC resume procedure (RRC resume procedure).

Physical random access channel resource: Physical Random Access Channel (PRACH) Resource. The base station broadcasts the physical random access channel parameter configuration used by the cell through system information. In the present disclosure, the physical random access channel resource PRACH resource may refer to the physical frequency resource and/or time domain resource and/or code used for random access. Domain resources (such as preamble).

Random Access Channel: Random Access Channel, RACH. Refers to the channel used to send the random access preamble. In the present disclosure, RACH may refer to either the transport channel RACH or the physical random access channel PRACH, without distinction. RACH parameters/configurations refer to the wireless configuration that implements the random access function, including PRACH related configurations, such as the maximum number of preamble transmissions, power boost parameters, random access response receiving window size, MAC contention resolution timer configuration, PRACH time-frequency resource configuration , Message 1 (ie preamble) subcarrier spacing, information used to indicate the number of synchronization channel blocks (Synchronization Signal Block, SSB) corresponding to each RACH opportunity (RACH occasion, RO) and the contention-based random preamble corresponding to each SSB The configuration of the number of preambles (configured by the ssb-perRACH-OccasionAndCB-PreamblesPerSSB information element), the backoff parameter (in the scalingFactorBI information element), etc. In the present disclosure, RACH resources are not distinguished from PRACH resources.

Four-step random access process: In the existing LTE mechanism, there are two four-step random access processes: contention-based random access (CBRA) and non-contention-based random access (that is, contention-based random access (CBRA) Access (Contention Free Random Access, CFRA)). The process of CBRA is shown in Figure 1 and is divided into four steps. In the first step, the UE sends a message 1 (ie, a random access preamble) to the base station. Step 2: The UE receives message 2 (ie, Random Access Response, RAR) from the base station, and the MAC RAR protocol data unit (Protocol Data Unit, PDU) contains multiple MAC sub-PDUs. Each MAC sub-PDU may be a MAC subheader including a backoff indication, a MAC subheader including a random access preamble RAPID, or a MAC subheader including a random access preamble RAPID and a corresponding RAR. The content of the RAR includes a time advance command, an uplink grant, a temporary cell radio network temporary identifier TC-RNTI, and the like. Step 3: The UE sends message 3 (uplink transmission scheduled by the uplink grant in message 2), which is generally used to send the UE identity to the base station for radio resource control (Radio Resource Control, RRC) connection RRC message for setup/restore/re-establishment or system information request, UE contention resolution identifier for random access contention resolution, etc.; Step 4: UE receives message 4 (ie, message for contention resolution) from the base station. The PRACH resource used in CBRA is shared by all UEs in the cell, and the random access process is successfully completed only when the UE completes the above four steps of random access of CBRA and the contention is successfully resolved. The process of CFRA is shown in FIG. 2 and includes two steps: the first step: the UE sends a message 1 (ie, a random access preamble) to the base station; the second step: the UE receives the message 2 from the base station. After successfully receiving message 2 associated with message 1, the UE considers that the CFRA procedure is successfully completed. In CFRA, the base station generally allocates dedicated PRACH resources such as a preamble to the UE in advance (referred to as step 0 in FIG. 2 ), so there is no contention and no contention resolution is required. Although the above CFRA contains only two main steps, it is also referred to as a four-step random access procedure in this disclosure. That is to say, the four-step random access procedure refers to the random access procedure in which only the random access preamble is sent in the first step.

Two-step random access procedure: refers to the two-step random access procedure introduced by the NR system of Release 16. Two-step random access can also be used for CBRA (as shown in Figure 3) and CFRA (as shown in Figure 4). In fact, the first and third steps in the above-mentioned four-step random access procedure are combined to send message A in the same step. That is, message A contains a random access preamble and the associated physical uplink shared channel PUSCH payload (payload) transmission. The content of the PUSCH payload is similar to that contained in message 3, which can include RRC messages or user plane data. , MAC control elements such as buffer status report BSR and UE identity. The second and fourth steps are combined into the same step called message B. Message B is the response to message A in the two-step random access process, and its content is similar to the content of the above-mentioned

messages

2 and 4, and can include the successful RAR (contention resolution identifier, HARQ feedback time for contention resolution) indication, physical uplink control channel resource indication, time advance command, cell wireless network temporary identifier (C-RNTI, etc.), backoff indication, fallback RAR (time advance command, uplink grant, TC-RNTI), and may also include The response RRC message corresponding to the RRC message included in the response message A, etc. Compared with four-step random access, the two-step random access process can shorten the delay of random access. Usually, the two-step random access adopts a different random access resource configuration from the four-step random access. In some cases, the UE may fall back to the process of four-step random access during two-step random access, for example, when receiving a fallback random access response (fallback Random Access Response, fallbackRAR) sent by the network side, Or when the number of attempts to send message A in the two-step random access exceeds a configured maximum number of times, etc.

When the MAC layer initiates a random access procedure, the UE needs to select the type of random access, that is, whether to perform a two-step random access or a four-step random access procedure. In the system of Release 16, when the UE is configured with CFRA resources of the four-step random access type, the UE performs four-step random access; when the UE is configured with CFRA resources of two-step random access, the UE performs two steps Random access process; and when the UE is not configured with CFRA resources, the UE selects the random access type according to the reference signal received power (Reference Signal Received Power, RSRP) measured by the downlink pathloss reference (downlink pathloss reference). When the RSRP is greater than a configured first RSRP threshold (the random access type selection RSRP threshold, which can be recorded as msgA-RSRP-Threshold), the UE performs two-step random access, otherwise, the UE performs four-step random access enter.

As mentioned above, one of the research goals of the Small Data Transmission (Small Data Transmission, SDT) project is to realize that the UE in the RRC_INACTIVE state sends small data packets during the random access process without entering RRC_CONNECTED. This kind of SDT based on the random access process can carry small data in message A of the two-step random access process or in message 3 of the four-step random access process. When the random access process is completed, it is considered that the SDT is completed. . During the entire SDT process, the UE remains in the RRC_INACTIVE state, which greatly reduces the signaling overhead brought by the traditional data transmission process, saves the UE energy consumption, and can also shorten the data transmission delay. When the RRC layer determines to use the SDT mechanism to send data, the RRC layer informs the lower layer to use the SDT mechanism, or the RRC layer sends an SDT indication to the lower layer. The lower layer includes the MAC layer, and the MAC layer thus triggers a random access procedure. The random access type setting procedure of the existing random access procedure does not involve and consider the SDT mechanism. Therefore, how to determine or set the type of the random access procedure in the random access procedure for SDT becomes the problem to be solved by the present disclosure.

The following embodiments provide solutions for how the UE determines or sets the random access procedure type in the case of performing SDT. It is worth noting that the SDT does not limit the name of the mechanism for transmitting small data in the RA process, and can also be named in other ways, such as early data transmission. The random access type refers to two-step random access or four-step random access; in some embodiments, the random access type may also refer to random access for SDT or random access for non-SDT access. The non-SDT random access refers to a random access procedure in which user plane data is not sent along with message 3 or message A.

Example 1

This embodiment 1 provides a method for determining the random access type according to the configured RACH resources when the random access process is initiated. The random access RACH resource or parameter configuration used for SDT is configured separately from the random access RACH resource or parameter configuration used for transmitting the random access procedure, ie, non-SDT.

As shown in FIG. 5, in step 501, when a random access procedure for small data transmission SDT is initiated, the RACH resources configured by the UE are determined.

Then, in step 503, it is determined according to the RACH resources configured by the UE whether to send small data by performing a two-step random access procedure or by performing a four-step random access procedure.

Specifically, when initiating a random access procedure, if the random access procedure is for SDT, if only the two-step random access for SDT is configured on the bandwidth part BWP for performing random access The incoming RACH resource, that is to say, there is no RACH resource configured for the four-step random access of SDT, the UE determines to perform the two-step random access procedure to send small data in message A. If only RACH resources for the four-step random access of SDT are configured on the bandwidth part BWP for performing random access, that is to say, no RACH resources for the two-step random access of SDT are configured, the UE determines that A four-step random access procedure is performed to send small data together with message 3. If both the four-step random access RACH resource for SDT and the two-step random access resource for SDT are configured on the bandwidth part BWP for performing random access, preferably, the UE determines to perform the random access for SDT. Two-step random access procedure of SDT; alternatively, if the RSRP referenced by the downlink path loss is higher than a second RSRP threshold, the UE performs a two-step random access procedure for SDT to send small data; if the following If the RSRP referenced by the line path loss is lower than or equal to the second RSRP threshold, the UE performs a four-step random access procedure for SDT to send small data.

The UE's determination to perform a two-step random access procedure can be described as the UE setting the random access type variable RA_TYPE to 2-step, and the UE's determination to perform a four-step random access procedure can be described as the UE setting the random access variable to 4-step step. Preferably, the second RSRP threshold value is a parameter configured by the network side through the RRC message, which is denoted as msgA-RSRP-Threshold-SDT here; when the network side does not configure the second RSRP threshold value, the UE It is considered that the second RSRP threshold value adopts the same value as the first RSRP threshold value. Alternatively, the second RSRP threshold and the first RSRP threshold are the same parameter. Optionally, the network side may configure multiple second RSRP thresholds. For example, each RSRP threshold corresponds to one or more PUSCH resources associated with msgA. At this time, the second RSRP threshold takes all the second RSRP thresholds. The smallest of the RSRP thresholds.

Preferably, the downlink path loss refers to the downlink of the primary cell.

Example 2

This embodiment 2 provides a method for determining the random access type according to the configured RACH resources and the RSRP referenced by the downlink path loss when the random access process is initiated. The random access RACH resource or parameter configuration used for SDT is configured separately from the random access RACH resource or parameter configuration used for transmitting the random access procedure, ie, non-SDT. In this embodiment 2, the random access type may refer to a random access procedure for SDT or a random access procedure for non-SDT.

When the MAC layer initiates a random access procedure for SDT, if only RACH resources for two-step random access for SDT are configured on the bandwidth part BWP for performing random access, but no RACH resources for SDT are configured For four-step random access RACH resources, the UE sets the random access type variable RA_TYPE to 2-step. The UE further determines that if the RSRP measurement value referenced by the downlink path loss is not higher than a second RSRP threshold value, the MAC layer falls back to the non-SDT random access procedure, and indicates to the upper layer (RRC layer) that SDT fallback has occurred , or inform the upper-layer SDT to cancel. Otherwise, if the RSRP measurement value of the downlink path loss reference is higher than the second RSRP threshold, the MAC layer continues to perform the random access procedure for SDT, using the RACH parameters for SDT and from the random access RACH for SDT Select an available resource among resources to send message A and small data.

Preferably, the downlink path loss refers to the downlink of the primary cell. The second RSRP threshold value is described in Embodiment 1.

Example 3

This embodiment 3 provides a method for determining the random access type according to the configured RACH resource and the transport block size (Transport Block Size, TBS) threshold when the random access process is initiated. The random access RACH resource or parameter configuration used for SDT is configured separately from the random access RACH resource or parameter configuration used for transmitting the random access procedure, ie, non-SDT.

When the MAC layer initiates a random access procedure for SDT, if the RACH resource for two-step random access for SDT is configured on the BWP performing the random access procedure, the UE further determines that the data to be sent contains small data. When the size of the MAC PDU is greater than a first TBS threshold, preferably, the UE determines to perform two-step random access, sets the random access type variable RA_TYPE to 2-step, and falls back to non-SDT random access. Enter the process, instruct the upper RRC layer to roll back the SDT process or notify the cancellation of the SDT process. Alternatively, if the RACH resource for the four-step random access of SDT is configured on the BWP, the UE determines to perform the four-step random access, sets the random access type variable RA_TYPE to 4-step, and performs the random access for SDT. The four-step random access procedure. Alternatively, if the RACH resource for the four-step random access of SDT is configured on the BWP but the size of the MAC PDU containing small data to be sent is greater than a second TBS threshold, that is, the MAC PDU is When the size is greater than both the first TBS threshold and the second TBS threshold, the UE falls back to the non-SDT random access procedure, and performs the random access type RA_TYPE determination of the non-SDT random access procedure. The determination of the random access type RA_TYPE for performing the non-SDT random access procedure refers to determining the random access type according to the RA_TYPE selection method in the non-SDT case in Release 16.

The size of the MAC PDU containing small data refers to the available uplink data for transmission plus the size of the corresponding MAC header, and may also include the size of one or more MAC control elements (Control Element, CE).

The first TBS threshold value or the second TBS threshold value may be directly configured through RRC signaling explicitly. It may also be calculated by the UE according to the configured or allocated uplink resources/parameters of the PUSCH used for sending the load of message A or message 3. Optionally, if more than one first TBS threshold value is configured or allocated, the first TBS threshold value in the above operation is the maximum value, or the selected value for sending the message A load is associated with the load. The calculated value of the PUSCH resource.

The following Embodiments 4 to 5 provide methods for determining the random access type when the number of times of sending the message A reaches the maximum number of transmissions in the two-step random access process for SDT.

Example 4

This embodiment 4 provides a random access type determination method when random access type backoff occurs.

In a two-step random access procedure for SDT, after the UE sends message A accompanied by small data, the UE starts a message B response window, and monitors and receives message B before the window times out. If the message B response window times out, the random access response reception is not considered to be successful, if the random access process is not completed.

At this time, in step 601, the UE determines whether the count value of the times of sending the random access preamble, PREAMBLE_TRANSMISSION_COUNTER, exceeds the configured maximum times of sending the message A, msgA-TransMax.

In step 603, if PREAMBLE_TRANSMISSION_COUNTER is equal to msgA-TransMax plus 1, the UE sets the random access type variable RA_TYPE to 4-step. At this time, if the four-step random access RACH resource for SDT is not configured, the UE falls back to the non-SDT four-step random access procedure, and sends an SDT cancellation indication to the upper RRC layer or informs the upper layer SDT to fall back.

Optionally, after the UE falls back to the non-SDT four-step random access process, in the subsequent random access process, the data in the UE update message 3 cache is non-SDT data, that is, the UE update message 3. The data in the cache is the data on the radio bearer that does not include user plane data. Optionally, the data in the update message 3 cache is non-SDT data and is executed after the UE receives the random access response, and the UE updates the message 3 cache according to the uplink grant UL grant in the received random access response. the MAC PDU.

Example 5

At this time, in step 701, the UE determines whether the count value PREAMBLE_TRANSMISSION_COUNTER of the sending times of the random access preamble exceeds the configured maximum sending times value msgA-TransMax of the message A.

In step 703, if PREAMBLE_TRANSMISSION_COUNTER is equal to msgA-TransMax plus 1, and the four-step random access resource for SDT is not configured, the UE continues the current two-step random access procedure without changing the value of the random access type RA_TYPE, and the UE Fall back to the non-SDT two-step random access process, send an SDT cancellation indication to the upper RRC layer or inform the upper layer SDT to fall back. Optionally, after the UE falls back to the non-SDT two-step random access process, in the subsequent random access process, the data in the UE update message A cache is non-SDT data, that is, the UE update message A. The data in the cache is the data on the radio bearer that does not include user plane data. Optionally, the data in the update message A cache is non-SDT data and is executed after the UE receives the random access response, and the UE updates message 3 according to the uplink grant (UL grant) in the received random access response. MAC PDUs in the cache. Optionally, the two-step random access process in which the UE falls back to non-SDT further includes that the UE flushes the message A buffer (flush MsgA buffer) or flushes the HAPQ buffer used for sending the MAC PDU in the message A buffer. That is to say, in the above case (PREAMBLE_TRANSMISSION_COUNTER is equal to msgA-TransMax plus 1), if the four-step random access resource for SDT is configured, the UE will change the value of the random access type RA_TYPE and set it to 4-step , perform a four-step random access procedure for SDT.

[Variation]

In the following, FIG. 8 is used to illustrate a user equipment that can execute the method performed by the user equipment described in detail above in the present invention as a modification.

As shown in FIG. 8 , the user equipment UE80 includes a processor 801 and a memory 802 . The processor 801 may include, for example, a microprocessor, a microcontroller, an embedded processor, or the like. The memory 802 may include, for example, volatile memory (eg, random access memory RAM), a hard disk drive (HDD), non-volatile memory (eg, flash memory), or other memory, or the like. Program instructions are stored on the memory 802 . When the instructions are executed by the processor 801, the above method described in detail in the present invention and executed by the user equipment can be executed.

In the present disclosure, some definitions or terms are common among different embodiments unless otherwise specified. In some cases, different embodiments may also work in harmony and are not mutually exclusive. For example, when the MAC layer determines the random access type, it can be one or more of the following conditions, the MAC determines that the random access type is two-step random access for SDT, and sets RA_TYPE to 2-step: When the two-step random access resource for SDT is configured on the BWP for random access, the size of the MAC PDU containing small data to be sent is not greater than the configured first TBS threshold, the downlink RSRP is greater than the second RSRP threshold; it may also be that when one or more of the following conditions are met, the MAC determines that the type of random access is four-step random access for SDT, and sets RA_TYPE to 4-step: when the Four-step random access resources for SDT are configured on the BWP for random access, and the size of the MAC PDU containing small data to be sent is not greater than the configured second TBS threshold. Optionally, when the RRC layer instructs the use of SDT, the MAC layer determines, according to the foregoing method, whether the initiated random access procedure type satisfies the two-step random access for SDT, and if so, determines the initiated random access procedure type. The random access procedure type is two-step random access for SDT, and RA_TYPE is set to 2-step; otherwise, the UE determines whether the initiated random access procedure type satisfies the four-step random access for SDT, and if so , then it is determined that the initiated random access procedure type is the four-step random access for SDT, and RA_TYPE is set to 4-step; otherwise, the UE falls back to the non-SDT procedure and performs the non-SDT random access procedure, And according to the existing mechanism, determine whether the random access procedure type is a two-step random access procedure or a four-step random access procedure.

In this application, "base station" refers to a mobile communication data and control switching center with larger transmit power and wider coverage area, including functions such as resource allocation and scheduling, and data reception and transmission. "User equipment" refers to a user's mobile terminal, for example, including a mobile phone, a notebook, and other terminal equipment that can wirelessly communicate with a base station or a micro base station.

The method and related apparatus of the present disclosure have been described above in conjunction with the preferred embodiments. Those skilled in the art will understand that the methods shown above are only exemplary. The methods of the present disclosure are not limited to the steps and sequences shown above. The base station and user equipment shown above may include more modules, for example, may also include modules that can be developed or developed in the future and that can be used for the base station, MME, or UE, and so on. The various identifiers shown above are only exemplary and not restrictive, and the present disclosure is not limited to the specific information elements exemplified by these identifiers. Numerous changes and modifications may occur to those skilled in the art in light of the teachings of the illustrated embodiments.

The program running on the device according to the present disclosure may be a program that causes a 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 (eg, random access memory RAM), a hard disk drive (HDD), non-volatile memory (eg, flash memory), or other memory systems.

A program for realizing the functions of the embodiments of the present disclosure 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" as used herein may be a computer system embedded in the device, and may include an operating system or hardware (eg, peripheral devices). The "computer-readable recording medium" may be a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a recording medium that dynamically stores a program for a short period of time, or any other recording medium readable by a computer.

The various features or functional blocks of the devices used in the above-described embodiments may be implemented or performed by electrical circuits (eg, 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. A general-purpose processor may be a microprocessor or any existing processor, controller, microcontroller, or state machine. The above circuit may be a digital circuit or an analog circuit. In the event that new integrated circuit technologies emerge as a result of advances in semiconductor technology to replace existing integrated circuits, 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 embodiments. While various examples of the described embodiments have been described, the present disclosure 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 disclosure have been described in detail with reference to the accompanying drawings. However, the specific structure is not limited to the above embodiments, 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 technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. In addition, the components described in the above-described embodiments having the same effect may be substituted for each other.

Claims

A method performed by a user equipment UE, comprising:

when initiating a random access procedure for small data transmission SDT, determining the random access channel RACH resource that the UE is configured with; and

Whether to send small data by performing a two-step random access procedure or by performing a four-step random access procedure is determined according to the RACH resources configured by the UE.
The method of claim 1, wherein,

If only the RACH resource for the two-step random access procedure of the SDT is configured on the bandwidth part for performing random access, the UE determines to send small data by performing the two-step random access procedure,

If only the RACH resource for the four-step random access procedure of the SDT is configured on the bandwidth part for performing random access, the UE determines to send small data by performing the four-step random access procedure,

If both the RACH resources used for the four-step random access process of the SDT and the RACH resources used for the two-step random access process of the SDT are configured on the bandwidth part for performing random access, when the downlink path loss When the referenced reference signal received power RSRP is higher than the second RSRP threshold, the UE determines to send small data by performing the two-step random access procedure, when the RSRP referenced by the downlink path loss is lower than or not higher than the second RSRP threshold. At the RSRP threshold, the UE determines to send small data by performing the four-step random access procedure.
The method of claim 1, wherein,

If only the RACH resource for the two-step random access procedure of the SDT is configured on the bandwidth part for performing random access, the UE determines to send small data by performing the two-step random access procedure,

When the UE further determines that the RSRP measurement value of the reference signal received power referenced by the downlink path loss is not higher than the second RSRP threshold, the UE falls back to the execution of the non-SDT random access procedure,

When the UE further determines that the RSRP measurement value referenced by the downlink path loss is higher than the second RSRP threshold value, the UE continues to perform the two-step random access procedure for the SDT.
The method of claim 1, wherein,

If the RACH resource for the two-step random access procedure of the SDT is configured on the bandwidth part for performing random access, when the UE further determines that the medium access control protocol data unit containing small data to be sent is When the size of the MAC PDU is greater than the first transport block size TBS threshold, the UE determines to send small data by performing the two-step random access procedure, and falls back to the execution of the non-SDT random access procedure.
The method of claim 1, wherein,

If the RACH resource for the two-step random access procedure of the SDT is configured on the bandwidth part for performing random access, when the UE further determines that the medium access control protocol data unit containing small data to be sent is When the size of the MAC PDU is larger than the first transport block size TBS threshold value, if the RACH resource for the four-step random access procedure of the SDT is configured on the bandwidth part for performing random access, the UE determines that the The four-step random access procedure is performed to transmit small data.
The method according to claim 1 or 5, wherein,

If the RACH resource for the four-step random access procedure of the SDT is configured on the bandwidth part for performing random access, when the UE further determines that the medium access control protocol data unit containing small data to be sent is When the size of the MAC PDU is greater than the TBS threshold value of the second transport block size, the UE falls back to the execution of the non-SDT random access procedure to select the random access type.
A method performed by a user equipment UE, comprising:

In the two-step random access process for small data transmission SDT, the UE determines whether the number of times the random access preamble is sent exceeds a specified threshold,

If the UE determines that the number of times the random access preamble is sent exceeds a specified threshold, when the UE is not configured with random access channel RACH resources for the four-step random access procedure of the SDT, the UE Fallback to non-SDT execution of the four-step random access procedure.
A method performed by a user equipment UE, comprising:

In the two-step random access process for small data transmission SDT, the UE determines whether the number of times the random access preamble is sent exceeds a specified threshold,

If the UE determines that the number of times the random access preamble is sent exceeds a specified threshold, when the UE is not configured with random access channel RACH resources for the four-step random access procedure of the SDT, the UE Fallback to non-SDT two-step random access procedure execution.
The method of claim 8, wherein,

When the UE is configured with RACH resources for the four-step random access procedure of the SDT, the UE determines to transmit small data by performing the four-step random access procedure.
A user equipment comprising:

processor; and

memory, storing instructions;

wherein the instructions, when executed by the processor, perform the method of any one of claims 1 to 9.