CN111787634B

CN111787634B - Random access method, base station and user equipment

Info

Publication number: CN111787634B
Application number: CN201910270192.0A
Authority: CN
Inventors: 沈霞; 朱颖
Original assignee: China Academy of Information and Communications Technology CAICT
Current assignee: China Academy of Information and Communications Technology CAICT
Priority date: 2019-04-04
Filing date: 2019-04-04
Publication date: 2022-05-24
Anticipated expiration: 2039-04-04
Also published as: WO2020200260A1; CN111787634A

Abstract

The invention provides a random access method, a base station and User Equipment (UE), wherein the method comprises the following steps: after receiving a first random access message sent by UE, a base station sends a random access response message to the UE; the MAC PDU of the random access response message comprises any one or combination of a plurality of message types of a first response message, a second response message and a third response message, and each response message corresponds to one MAC PDU subunit; the first response message is a response message when the base station correctly detects the leader sequence but does not correctly detect the load carried by the PUSCH; the second response message is a response message when the base station correctly detects the load carried by the leader sequence and the PUSCH; and the third response message is the response message when the base station correctly detects the preamble sequence but does not have the load borne by the PUSCH correspondingly. The invention can reduce signaling overhead and random access time delay through the 2-step RACH and support 2-step RACH retransmission.

Description

Random access method, base station and user equipment

Technical Field

The present invention relates to the field of wireless communication technologies, and in particular, to a random access method, a base station, and a user equipment.

Background

In the existing 4G and 5G random access procedures of the 4-step RACH based on the contention-based four-step random access channel, at least four signaling interactions are required between the User Equipment (UE) and the base station (eNB), as shown in fig. 1, for example, as follows:

-a first time: the user equipment sends Msg1 to the base station, and the Msg1 selects a leader sequence for the user equipment, and is used for the base station to estimate Timing Advance (TA) and the like;

-a second time: the base station sends Msg2 to the user equipment, wherein Msg2 is a random access response of Msg1, and the random access response comprises a leader sequence identifier (RAPID), a TA, an uplink Grant (UL Grant) for the user equipment to send Msg3 to the base station, a temporary cell radio network temporary identifier (TC-RNTI) and the like;

-a third time: the user equipment sends Msg3 to the base station, when the user equipment reads a leader sequence identifier corresponding to Msg1 in Msg2, the Msg3 is sent again, and the content of the Msg3 is related to an event for triggering a random access process;

-fourth time: and the base station sends the Msg4 to the user equipment, and the Msg4 is a response for solving the contention conflict, and when the Msg4 detected by the user equipment contains the relevant identification information in the corresponding Msg3, the random access is considered to be successful.

The random access response message currently contains two kinds of Msg2 and Msg4, wherein Msg2 is a common message, i.e. the message that the base station includes Msg1 responses sent for multiple UEs in one MAC PDU occurs, as shown in fig. 2:

the MAC PDU includes a plurality of MAC PDU sub-units (MAC sub-PDUs). Wherein, MACsub PDU 1(BI only) consists of five fields (E/T/R/R/BI). MAC sub PDU 2(RAPID only), consisting of three fields (E/T/RAPID). MAC sub PDU3 to MAC sub PDU n, each MAC sub PDU comprising a subheader consisting of three fields (E/T/RAPID) and a payload (MAC RAR). Each MAC RAR consists of four fields (R/Timing Advance Command/UL Grant/TC-RNTI).

And the UE identifies that the RAPID information in the Msg2 corresponds to the MAC sub PDU which sends the leader sequence in the Msg1 as the response information of the UE. And for the Msg4 which is random access contention conflict response information, wherein the contention conflict resolution identity is included, the Msg4 is generated in association with TC-RNTI or C-RNTI, the UE performs Msg4 detection through the TC-RNTI or C-RNTI, and further judges whether the Msg4 includes CCCH SD (first 48 bits) sent in the Msg3 or not to judge whether the response information corresponds to the Msg4 or not.

According to the above description, in order to reduce the signaling overhead and the random access delay, the random access procedure is performed through at least two signaling interactions between the UE and the base station, which is called a two-step random access channel 2-step RACH, and the random access procedure is exemplified as follows:

for the first time: the UE sends MsgA to the base station and takes on the functions of Msg1 and Msg3 in the 4-step RACH;

and (3) for the second time: the base station sends MsgB to the UE, bears the functions of Msg2 and Msg4 in the 4-step RACH, and is mainly used for indicating TA of random access, C-RNTI distribution, uplink data transmission authorization, contention conflict resolution and the like.

Therefore, how to generate MsgB to reduce signaling overhead and random access delay becomes an issue to be solved.

Disclosure of Invention

In view of this, the present invention provides a random access method, a base station, and a user equipment, which can reduce signaling overhead through a 2-step RACH, quickly respond to random access information to UEs using different random access methods, and reduce random access delay.

In order to achieve the purpose of the invention, the technical scheme of the invention is realized as follows:

the invention discloses a random access method, which comprises the following steps:

after receiving a first random access message sent by User Equipment (UE), a base station sends a random access response message to the UE to indicate the UE to carry out random access; the first random access message comprises at least one information of Preamble sequence Preamble and load carried by uplink shared channel PUSCH;

the media access control protocol data unit (MAC PDU) of the random access response message comprises any one or combination of a plurality of message types of a first response message, a second response message and a third response message, and each response message corresponds to one MAC PDU subunit;

the first response message is a response message when the base station correctly detects the leader sequence but does not correctly detect the load carried by the PUSCH;

the second response message is a response message when the base station correctly detects the load carried by the leader sequence and the PUSCH;

and the third response message is the response message when the base station correctly detects the preamble sequence but does not have the load borne by the PUSCH correspondingly.

The invention also discloses a base station, which comprises a first receiving module, a first processing module and a sending module;

the first receiving module is used for receiving a first random access message sent by User Equipment (UE) and sending the first random access message to the first processing module; the first random access message comprises at least one information of Preamble sequence Preamble and load carried by uplink shared channel PUSCH;

the first processing module is used for generating a random access response message according to the first random access message and sending the random access response message to the sending module; the media access control protocol data unit (MAC PDU) of the random access response message comprises any one or combination of a plurality of message types of a first response message, a second response message and a third response message, and each response message corresponds to one MAC PDU subunit;

the third response message is a response message when the base station correctly detects the leader sequence but does not have the load borne by the PUSCH correspondingly;

the sending module is configured to send a random access response message to the UE.

The invention also discloses User Equipment (UE), which comprises a second receiving module and a second processing module;

the second receiving module, configured to detect whether to send a response message content corresponding to the first random access message for the second receiving module after receiving the random access response message according to claim 8; the corresponding response message content includes: RAPID corresponding to the sent preamble sequence and/or response message corresponding to the load carried by the sent PUSCH;

the second processing module is used for processing the data,

the second receiving module is used for detecting that the second receiving module sends the response message content corresponding to the first random access message, wherein the response message content comprises a RAPID corresponding to the sent leader sequence and corresponds to a load without PUSCH bearing, and the random access is reinitiated according to a system configuration random access retransmission mechanism;

the second receiving module is used for further judging whether to feed back the confirmation information of correctly receiving the response message according to the system configuration when detecting that the second receiving module sends the response message content corresponding to the first random access message by itself, wherein the response message content comprises a RAPID corresponding to the sent preamble sequence and a response message corresponding to the load carried by the sent PUSCH;

and the random access module is used for reinitiating random access according to a random access retransmission mechanism configured by the system when the second receiving module does not receive the response message content corresponding to the first random access message sent by the second receiving module in the time window configured by the system for receiving the response message.

According to the technical scheme, the MsgB is generated, the MsgB comprises any one or combination of multiple message types of a first response message, a second response message and a third response message, and each response message corresponds to one MAC PDU subunit; the first response message is a response message when the base station correctly detects the leader sequence but does not correctly detect the load carried by the PUSCH; the second response message is a response message when the base station correctly detects the load carried by the leader sequence and the PUSCH; and the third response message is the response message when the base station correctly detects the preamble sequence but does not have the load borne by the PUSCH correspondingly. The random access response message design of the 2-step RACH can support 2-step RACH retransmission, support quick response of random access information to UE adopting different random access methods, reduce random access time delay and reduce response information signaling overhead by combining different response information.

Drawings

Fig. 1 is a flowchart illustrating a conventional random access procedure.

Fig. 2 is a diagram illustrating a format of a conventional MAC PDU.

Fig. 3 is a flow chart illustrating a random access procedure of the present invention.

Fig. 4 is a schematic structural diagram of a base station according to the present invention.

Fig. 5 is a diagram illustrating a format of a first response message MAC sub pdu according to an embodiment of the present invention.

Fig. 6 is a diagram illustrating a format of a second MAC sub pdu according to a second embodiment of the present invention.

Fig. 7 is a diagram illustrating a MAC RAR in a third first response message MAC subPDU according to an embodiment of the present invention.

Fig. 8 is a diagram of a MAC PDU including a first response message and a third response message in a random access response message according to an embodiment of the present invention.

Fig. 9 is a diagram of a MAC PDU including a first response message and a third response message in a random access response message according to another embodiment of the present invention.

Fig. 10 is a diagram illustrating a MAC PDU including a first response message, a second response message, and a third response message in a random access response message according to an embodiment of the present invention.

Fig. 11 is a diagram of a MAC PDU including a first response message, a second response message, and a third response message in a random access response message according to another embodiment of the present invention.

Fig. 12 is a schematic structural diagram of a user equipment provided in the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and examples.

Example one

The flow chart of the random access method of the invention is shown in fig. 3, and comprises the following steps:

step 31, a User Equipment (UE) sends a first random access message to a base station, wherein the first random access message comprises at least one information of a Preamble sequence (Preamble) and a load borne by a PUSCH;

random access technology is an important technology for medium access control in communication systems. The random access is triggered and initiated by a random access event, that is, when the UE satisfies a random access event triggering condition, a random access procedure is initiated. The main random access triggering event comprises the purposes of initial access of UE, connection reconstruction and switching of Radio Resource Control (RRC), uplink and downlink data achievement in an asynchronous state and the like. Therefore, the message related to the event triggering the random access procedure, which is included in the random access message sent by the UE to the base station, is a message related to initial access, RRC connection reestablishment, or handover of the UE, and is carried by an uplink shared channel PUSCH. In 2-step RACH, the first random access message is also called MsgA and includes a preamble sequence and a load (payload) of a PUSCH bearer, where the load (payload) of the PUSCH bearer corresponds to the message related to the event triggering the random access procedure.

Further, when the random access event triggering condition is met, the UE selects at least one of a 2-stepRACH mode and a 4-stepRACH mode to initiate random access according to the random access configuration and the measurement result. When the UE initiates random access by adopting the 4-step RACH, the first random access message comprises a Preamble sequence (Preamble). When UE initiates random access by adopting 2-step RACH, the first random access message comprises a Preamble sequence (Preamble) and a load borne by a PUSCH.

Step 32, after receiving a first random access message sent by user equipment, the base station sends a random access response message to the UE, and indicates the UE to perform random access;

a media access control protocol data unit (MAC PDU) of the random access response message comprises any one or a combination of a plurality of message types of a first response message, a second response message and a third response message, and each response message corresponds to one MAC PDU subunit; wherein, a MAC PDU subunit comprises a header and a load. For preamble sequence ID or random access retransmission back-off information, the part of the subunit header is generally contained, and the part of the MAC PDU subunit load generally contains other response information indications, such as advance timing, uplink grant, TC-RNTI and the like.

The first response message is a response message when the base station correctly detects the leader sequence but does not correctly detect the load carried by the PUSCH; the load in the MAC PDU subunit corresponding to the first response message includes: timing advance TA, uplink authorization information UL Grant and one or more combinations of temporary cell radio network temporary identification TC-RNTI fields; and the base station further detects the load carried by the PUSCH on the resource corresponding to the leader sequence after the correct detection of the leader sequence according to the transmission resource mapping relation of the leader sequence configured by the system and the load carried by the PUSCH.

The second response message is a response message when the base station correctly detects the load carried by the leader sequence and the PUSCH; the load in the MAC PDU subunit corresponding to the second response message includes: a response message corresponding to the load carried by the PUSCH;

the third response message is a response message when the base station correctly detects the leader sequence but does not have the load borne by the PUSCH correspondingly; the load in the MAC PDU subunit corresponding to the third response message includes: TA, UL Grant and TC-RNTI fields. Wherein, the load corresponding to the no-PUSCH bearer indicates that the base station judges, according to the random access configuration and the detected preamble sequence, that the random access message sent by the UE device only includes the preamble sequence without the PUSCH bearer load (for example, 4-step RACH condition); or, according to the resource configured to transmit the load carried by the PUSCH corresponding to the preamble sequence, it is determined by means of energy detection or the like that no information is transmitted at the resource location (for example, when the preamble sequence and the preamble sequence transmission resource are shared by the 4-step RACH and the 2-step RACH). The third response message corresponds to response information of the first random access message sent by the UE by adopting the 4-step RACH in the application.

Preferably, in order to distinguish the first response message, the second response message and the third response message of each message type, the MAC PDU sub-unit of the random access response message for different message types includes bits for distinguishing each message type.

Preferably, when the load in the MAC PDU subunit corresponding to the first response message includes a timing advance information TA, an uplink Grant information UL Grant and a temporary cell radio network temporary identifier TC-RNTI field, a field value that does not need to be indicated is set to zero.

Preferably, the two-step random access channel retransmission backoff indication BI and the four-step random access channel retransmission backoff indication BI in the MAC PDU of the random access response message are configured in common or independently.

Specifically, when the 2-step RACH and the 4-step RACH configure retransmission backoff timing mechanisms independent of each other, a MAC PDU of the random access response message includes a first retransmission backoff indication BI and a second retransmission backoff indication BI, and MAC PDU subunits for different BIs include bits for distinguishing different BIs; the first BI is a two-step random access channel retransmission backoff indication BI and is used for indicating the UE to re-initiate two-step random access by applying the first BI after the random access fails; and the second BI is a four-step random access channel retransmission backoff indication BI and is used for indicating the UE to re-initiate the four-step random access by applying the second BI after the random access fails.

Specifically, when the 2-step RACH and the 4-step RACH share the same retransmission backoff timing mechanism, the MAC PDU of the random access response message includes a third retransmission backoff indication BI, and the third BI is used for indicating the UE to reinitiate the two-step random access or the four-step random access after the random access fails.

Based on the same inventive concept, the present invention further provides a base station, a schematic structural diagram of which is shown in fig. 4, where the base station includes a first receiving module 401, a first processing module 402, and a sending module 403;

the first receiving module 401 is configured to receive a first random access message sent by a user equipment UE, and send the first random access message to the first processing module 402; the first random access message comprises at least one information of Preamble sequence Preamble and load carried by uplink shared channel PUSCH;

the first processing module 402 is configured to generate a random access response message according to the first random access message, and send the random access response message to the sending module; the media access control protocol data unit (MAC PDU) of the random access response message comprises any one or combination of a plurality of message types of a first response message, a second response message and a third response message, and each response message corresponds to one MAC PDU subunit;

the sending module 403 is configured to send a random access response message to the UE.

For the purpose of clearly illustrating the invention, specific examples are set forth below.

Firstly, system configuration random access response message format and parameter, random access retransmission mechanism and random access response Generation mode of MAC PDU (media Access control protocol data Unit) in response message

The method is characterized in that: system configuration 2-stepRACH and 4-stepRACH response message formats and parameters

At the base station side, the following information in the RACH needs to be detected, and a response message is carried out according to the detection result

1) Msg1 in 4-stepRACH in response to Msg2 in 4-stepACH

2) Msg3 in 4-stepRACH in response to Msg4 in 4-stepACH

3) MsgA in 2-stepRACH, to which MsgB in 2-step RACH is responded

Wherein 3) above may further include a UE feedback response message for correctly detecting the preamble sequence of MsgA and incorrectly detecting the load carried by PUSCH, and a UE feedback response message for correctly detecting the preamble sequence of MsgA and the load carried by PUSCH. Wherein MsgA and Msg1 correspond to application examples in which different random access modes are applied in the first random access message. When random access is initiated by using 2-stepRACH, the first random access message corresponds to MsgA, and when random access is initiated by using 4-stepRACH, the first random access message corresponds to Msg 1. MsgA includes a preamble and a PUSCH-carried payload, and Msg1 includes a preamble.

The invention refers to the response message for correctly detecting the leader sequence of the MsgA sent by the 2-step RACH and incorrectly detecting the load borne by the PUSCH as a first response message; the response message for sending the preamble sequence of MsgA and correctly detecting the load carried by PUSCH aiming at the 2-step RACH is called as a second response message; the response message Msg2 for 4-stepRACH Msg1 is referred to as a third response message. When the base station end assembles response messages of a plurality of UE into one MAC PDU and sends the MAC PDU to the UE, the response message corresponding to the UE is a certain subunit (sub PDU) of the MAC PDU.

For the first response message: the format of the response message comprises leading sequence ID (RAPID), TA indication, TC-RNTI indication, uplink authorization and other indications. Part of the information can be used as an optional item, and the contained information content is determined according to the system configuration. The response message format represents the same concept as the format of the MAC sub pdu corresponding to the response message (the same applies hereinafter). For example, the response message format includes the following three types:

the first method comprises the following steps: the first response message format contains a preamble sequence id (rapid) and a TA indication. Fig. 5 is a schematic diagram of a format of a response message, where fig. 5 is a schematic diagram of a first format of a first response message MAC sub pdu according to an embodiment of the present invention. Expressed as: subheader (E + T + RAPID) + payload (TA). The MAC subPDU includes a subheader (subheader) and a Payload (Payload), which is a MAC RAR.

Wherein, an "E" field is included in the subheader to indicate whether the subPDU is the last one, a "T" field is included to indicate whether RAPID information is included, RAPID indicates a preamble sequence ID, an "R" field in the payload field is a reserved bit, and TA indicates timing advance information.

And the second method comprises the following steps: the first response message format contains a preamble sequence ID, TA and TC-RNTI indication. Fig. 6 is a schematic diagram of a format of a response message, where fig. 6 is a schematic diagram of a format of a mac sub pdu of a second response message according to the embodiment of the present invention.

Expressed as:subheader(E+T+RAPID)+Payload(TA+TC-RNTI)。

and adding 'TC-RNTI' information compared with the first format for generating the PUSCH during the MsgA retransmission.

And the third is that: the first response message format multiplexes the response message format of the existing RACH, wherein the payload part of the formatted mac sub pdu is shown in fig. 7, and the content not contained in the response message is zeroed. For example, when the uplink authorization is not fed back, the content of the uplink authorization part in the message format is set to be zero. The length of the response message format is the same as that of the existing RACH.

FIG. 7 is a diagram of a third first response message MAC sub PDU according to an embodiment of the present inventionMAC RAR diagram of (1). Expressed as:Payload(TA+ULGRANT+TC-RNTI)。

further, when configuring random access response messages of different lengths to be assembled into one MAC PDU in addition to the MAC sub-PDU containing only the preamble sequence ID or the backoff indicator, the system further configures a bit field in the response message MAC sub-PDU to indicate a response message format to which the MAC sub-PDU belongs. For example, in fig. 5, fig. 6, or fig. 7, the reserved bit is further used to indicate that the format of the response message to which the MAC sub pdu belongs corresponds to the response message that the MsgA preamble sequence in the 2-step RACH is correctly detected and the load carried by the PUSCH is not correctly detected.

For the second response message: when UE sends MsgA by using 2-step RACH, the leader sequence and the load borne by PUSCH are correctly detected, according to the requirements of different RACH trigger events, the content of the designed random access response message corresponds to the trigger event, and the random access response message can contain information such as leader sequence ID, TA, competition conflict resolution identification, TC-RNTI and the like. And part of information is used as an optional item, and the specific contained information content is determined according to the system configuration and the trigger event. For example, if the UE includes C-RNTI information in the MsgA, TC-RNTI information may not be included in the response message.

And (2) feature: system configuration 2-stepACH retransmission mechanismThe configuration comprises the following steps:

1) configuring the maximum MsgA transmission times, and when the MsgA transmission times exceed the configured maximum transmission times and the random access is not successful, returning to 4-step RACH to initiate Msg1 transmission or initiating Msg3 transmission based on scheduling (the base station allocates uplink grant for Msg3 transmission); for example, when the maximum number of MsgA transmissions is configured to be 1, and the base station detects that the MsgA preamble sequence is correctly detected and the load carried by the PUSCH is not correctly detected, the 2-step RACH fallback to the 4-step RACH for sending the uplink grant transmitted by Msg3 may be fed back in the response message.

2) Configuring MsgA self-adaptive retransmission or non-self-adaptive retransmission, and reselecting a leader sequence and a corresponding PUSCH resource for the self-adaptive retransmission during retransmission; and selecting the same preamble sequence and PUSCH resource position during retransmission for non-adaptive retransmission to support the base station to perform HARQ combination detection on the MsgAPUSCH transmission.

Further, in a scenario where the preamble sequence of the MsgA is correctly detected and the load of the PUSCH bearer is not correctly detected in the non-adaptive retransmission, the next retransmission may be configured to retransmit only the load of the PUSCH bearer. Under this configuration, when the UE detects the first response message corresponding to MsgA, then the next MsgA retransmission retransmits only the load of the PUSCH bearer when MsgA does not exceed the maximum number of retransmissions.

Further, for a load scenario of a non-adaptive retransmission PUSCH bearer only, the response message may be configured to contain TC-RNTI information, and the load of the retransmission PUSCH bearer is generated based on the TC-RNTI in the response message.

Further, the base station may configure the retransmission timing information to indicate a time when the UE retransmits the load of the PUSCH bearer next time, wherein the retransmission timing information may be indicated in a response message or the UE is informed of the configuration information by the base station in an RRC configured manner.

3) Configuring a value list of retransmission back-off indication BI of MsgA, which can specify that BI in 2-step RACH and BI in 4-step RACH share the same list, or independently designing a new retransmission back-off indication list for retransmission of 2-step RACH.

Further, the above configuration information 1), 2), and 3) may be included in configuration information about 2-stepRACH in RRC signaling and notified to the UE by the base station; or the base station notifies the UE of the information contained in a Physical Downlink Control Channel (PDCCH); or written in the base station and the UE through the device configuration.

The retransmission of the 2-step RACH is the random access re-initiation, and according to the system configuration, the UE that is initiating the random access by using the 2-step RACH may include the following 4 random access re-initiations: the first is to initiate retransmission of the preamble sequence of MsgA and PUSCH bearer payload with 2-step RACH, the second is to initiate retransmission of PUSCH bearer payload only with 2-step RACH, the third is to fallback to 4-step ach to initiate transmission of Msg1, and the fourth is to fallback to 4-step RACH to initiate transmission of Msg 3.

And (3) feature: the system configures a generation mode of a random access response message MAC PDU.In this manner, a 2-step RA is embodiedMultiplexing relationship between CH and 4-step RACH response messages. And determining whether the random access response message aiming at the 2-step RACH MsgA and the 4-step RACH response message Msg2 are assembled into one MAC PDU or not according to the generation mode of the random access response message MAC PDU. Including the format in which one or more of the first response message, the second response message, and the third response message are assembled into one MAC PDU. Examples are as follows:

(1) the first response message and the third response message are assembled into one MAC PDU

Further, when the 4-step RACH and the 2-step RACH share the same retransmission backoff timing mechanism, the MAC subPDU in the RACH response message MAC PDU fed back by the base station includes the following types:

1) MAC subpPDU 1 indicates BI only

2) MAC subpPDU 2 indicates only preamble sequence ID

3) The MAC sub pdu3 indicates a third response message, the subheader indicates a preamble sequence ID, and the load indicates TA, TC-RNTI, and uplink grant. Wherein the load diagram is shown in figure 7.

4) MAC subpPDU 4 denotes a first response message

Wherein the 4) MAC sub-pdu 4 may further include multiple response message formats to support the inclusion of different response message contents, such as including one or more of the formats of fig. 5, 6, and 7 described above. When 4) contains one format and the same response message format is used as in 3), the format type is changed to the first three. The MAC PDU may contain certain zero padding bits, i.e., padding as shown in fig. 8, according to the size of the transmission packet. Fig. 8 is a diagram of a MAC PDU including a first response message and a third response message in a random access response message according to an embodiment of the present invention. Where "MAC subPDU 1" is an illustration to indicate only BI. "mac sub pdu 2" is an illustration to indicate only a preamble sequence ID. The RAPID + RAR of the MAC sub PDU3 indicates the leader sequence ID, the load indicates TA, TC-RNTI and the uplink authorization. "2-steplach MAC RAR type 1" is a payload part of the first response message MAC subPDU.

Further, when the 4-step RACH and the 2-step RACH configure mutually independent retransmission backoff timing mechanisms, the MAC sub-PDU in the RACH response message MAC PDU fed back by the base station includes the following types:

1) MAC subpPDU 1 indicates only BI for 4-step RACH

2) MAC subpPDU 2 indicates only BI for 2-step RACH

3) MAC subpPDU 3 indicates only preamble sequence ID

4) The MAC sub pdu4 indicates a third response message, the subheader indicates a preamble sequence ID, and the load indicates TA, TC-RNTI, and uplink grant. Wherein the load diagram is shown in figure 7.

5) The MAC sub pdu5 represents a first response message

Wherein 5) above may further comprise a plurality of response message formats to support the inclusion of different response message contents, for example, one or more formats including 5, 6, 7 above. When 5) contains one format and the same response message format as in 4) is used, the format type is changed to the first 4. The mac pdu may contain some zero padding bits, i.e. padding as shown in fig. 9, according to the size of the transmission packet. Fig. 9 is a diagram of a mac pdu including a first response message and a third response message in a random access response message according to another embodiment of the present invention. Where "MAC subpPDU 1" is a BI indication that indicates only for 4-step RACH. "MAC subpPDU 2" is a BI indication that indicates only for 2-step RACH.

Further, in order to distinguish which one of the 4-step RACH and the 2-step RACH a sub pdu indicating "BI" belongs to, bits other than the bits occupied by the packet header "BI" are used to perform a backoff indication indicating that the BI information belongs to the 4-step RACH UE or a backoff indication of the 2-step RACH UE, for example, one of the reserved bits "R" is designed as a new indication field, a value of 1 identifies the UE response of the "BI" belonging to the 2-step RACH, and a value of "0" identifies the UE response of the "BI" belonging to the 4-step RACH; or a value of 0 identifies the UE response of the "BI" belonging to the 2-step RACH, and a value of 1 identifies the UE response of the "BI" belonging to the 4-step RACH.

(2) The first response message, the second response message, and the third response message are assembled into one MAC PDU.

Further, when the 4-step RACH and the 2-step RACH share the same retransmission backoff timing mechanism, the MAC subPDU format in the RACH response message MAC PDU fed back by the base station includes the following types:

1) MAC subpPDU 1 indicates BI only

2) MAC subpPDU 2 indicates only preamble sequence ID

4) The MAC sub pdu4 represents a first response message

5) The MAC sub pdu5 represents a second response message

Wherein 4) above may further comprise a plurality of response message formats to support the inclusion of different response message contents, for example, one or more formats including 5, 6, 7 above. When 4) contains one format and the same subPDU format as 3) is used, format types 4) and 3) can be combined into one. The above 5) may further comprise a plurality of response message formats according to the system configuration, so as to correspondingly meet the requirements of different triggering event response message contents. The MAC PDU may contain some zero padding bits, i.e., padding as shown in fig. 10, according to the size of the transmission packet. Fig. 10 is a diagram illustrating a MAC PDU including a first response message, a second response message, and a third response message in a random access response message according to an embodiment of the present invention. Wherein "2-step RACH MAC RAR type 1" is an indication of payload portion of the first response message MAC subPDU. "2-step RACH MAC RAR type 2" is an indication of the payload portion of the second response message mac sub pdu.

Further, when the 4-step RACH and the 2-step RACH configure mutually independent retransmission backoff timing mechanisms, the MAC subPDU format in the RACH response message MAC PDU fed back by the base station includes the following types:

1) MAC subpPDU 1 indicates only BI for 4-step RACH

2) MAC subpPDU 2 indicates only BI for 2-step RACH

3) MAC subpPDU 3 indicates only preamble sequence ID

4) The MAC sub pdu4 indicates a third response message, the subheader indicates a preamble sequence ID, the load indicates TA, TC-RNTI, and the uplink grant. Wherein the load diagram is shown in figure 7.

5) The MAC sub pdu5 represents a first response message

6) The MAC sub pdu6 represents a second response message

Wherein 5) above may further comprise a plurality of response message formats to support the inclusion of different response message contents, for example, one or more formats including 5, 6, 7 above. When 5) contains one format and the same subPDU format is used as in 4), format types 5) and 4) can be combined into one. Above 6) may further comprise a plurality of response message formats according to the system configuration, so as to meet the requirements of different trigger event response message contents. The MAC PDU may contain some zero padding bits, i.e., padding as shown in fig. 11, according to the size of the transmission packet. Fig. 11 is a diagram of a MAC PDU including a first response message, a second response message, and a third response message in a random access response message according to another embodiment of the present invention. In order to distinguish which one of 4-step RACH and 2-step RACH a sub PDU indicating "BI" belongs to, bits except bytes occupied by a packet header "BI" are required to be used for indicating the rollback indication that the BI information belongs to 4-step RACH UE or the rollback indication of 2-step RACH UE, for example, one reserved bit "R" is designed into a new indication domain, the value of 1 identifies the UE response that the "BI" belongs to 2-step RACH, and the value of 0 identifies the UE response that the "BI" belongs to 4-step RACH; or a value of 0 identifies the UE response of the "BI" belonging to the 2-step RACH, and a value of 1 identifies the UE response of the "BI" belonging to the 4-step RACH.

(3) The first response message and the second response message are assembled into one MAC PDU. The MAC PDU is independent of the 4-step RACH response message.

The MAC subpPDU in the 2-step RACH response message MAC PDU fed back by the base station comprises the following types:

1) MAC subpPDU 1 indicates BI only

2) MAC subpPDU 2 indicates only preamble sequence ID

3) The MAC sub pdu3 represents a first response message

4) The MAC sub pdu4 represents a second response message

Wherein 2) above may not include the type of sub-pdu when there is no corresponding need to feed back only the preamble sequence ID in the 2-step RACH. Above 3) may further comprise a plurality of response message formats to support the inclusion of different response message contents, for example, one or more formats including above fig. 5, 6, 7. The above 4) may further comprise a plurality of response message formats according to the system configuration, so as to correspondingly meet the requirements of different triggering event response message contents. The MAC PDU may contain certain zero padding bits depending on the transport packet size.

(4) The first response message is assembled into one MAC PDU. The MAC PDU is independent of the 4-step RACH response message.

The MAC sub PDU in the MAC PDU assembled by the first response message fed back by the base station comprises the following types:

1) MAC subpPDU 1 indicates BI only

2) MAC subpPDU 2 indicates only preamble sequence ID

3) The MAC sub pdu3 represents a first response message

Wherein 2) above may not include the type of sub-pdu when there is no corresponding need to feed back only the preamble sequence ID in the 2-step RACH. Above 3) may further comprise a plurality of response message formats to support the inclusion of different response message contents, for example, one or more formats including above fig. 5, 6, 7. The mac pdu may contain certain zero padding bits depending on the transport packet size.

Further, the system configuration of the multiplexing relationship between the 2-step RACH and 4-step RACH response messages and the 2-step RACH response message design may be embodied in the MAC PDU design of the RACH response message or configured through higher layer signaling. The system determines the format and parameters of the MAC PDU of the 2-step RACH response message through the format design embodiment or the high-level configuration of the MAC PDU.

Further, when different types of response messages need to be assembled into one MAC PDU as described above, one or more bits are configured in a sub-PDU format corresponding to the response message to indicate the message type. For example, when the first response message and the third response message are assembled into one MAC PDU, the system may configure one or more bit fields in the first response message to indicate that the response message corresponding to the sub PDU belongs to the first response message of the 2-step RACH when the MAC sub PDU formats of the first response message and the third response message are different. Accordingly, the system may configure one or more bit fields in the third response message to indicate that the response message corresponding to the subPDU belongs to the third response message.

Further, the system configuration distinguishes the cell format type by a random access correlation identifier. When the terminal can identify the information format to which the currently detected MAC sub-pdu belongs according to the random access correlation identifier, it is not necessary to configure one or more bit fields in the response message format to indicate the response message format to which the MAC sub-pdu belongs. For example, when the system configures the 2-step RACH and the 4-stepach to use different preamble sequence IDs, when configuring the first response message and the third response message to be assembled into one MAC pdu, the terminal may determine whether the information format of the currently detected MAC sub-pdu is the 4-stepach response message format by identifying the preamble sequence ID.

Further, the generation mode of the response message MAC PDU may be included in configuration information about random access in RRC signaling, and notified to the UE by the base station; or the base station notifies the UE of the PDCCH; or written in the base station and the UE through the equipment configuration.

Secondly, the base station feeds back RACH response message to the UE

1) Msg1 in 4-stepRACH in response to Msg2 in 4-stepACH

2) Msg3 in 4-stepRACH in response to Msg4 in 4-stepACH

3) MsgA in 2-stepRACH, to which MsgB in 2-step RACH is responded

Wherein 3) above can further include a UE feedback response message for correctly detecting the preamble sequence of MsgA and incorrectly detecting the load of PUSCH bearer, and a UE feedback response message for correctly detecting the preamble sequence of MsgA and the load of PUSCH bearer.

And the base station generates a response message according to the system configuration and sends the response message to the UE.

Example two

On the other hand, the random access response message of the invention can support multiple retransmissions of 2-step RACH. In particular, the amount of the solvent to be used,

after receiving the random access response message, the UE detects whether response message content corresponding to a first random access message is sent for the UE; the corresponding response message content includes: RAPID corresponding to the sent preamble sequence and/or response message corresponding to the load carried by the sent PUSCH;

the first condition is as follows: if the content of the response message corresponding to the first random access message is sent by the UE, wherein the content of the response message comprises an RAPID corresponding to the sent preamble sequence, but the response message does not correspond to the load carried by the sent PUSCH, the situation that the base station correctly detects the preamble sequence but does not correctly detect the load carried by the PUSCH when the UE adopts 2-stepRACH to initiate random access is correspondingly met, or the situation that the base station only correctly detects the preamble sequence when the UE adopts 4-stepRACH to initiate random access;

case two: if the content of the response message corresponding to the first random access message is sent by the UE, wherein the content of the response message comprises an RAPID corresponding to the sent preamble sequence and a response message corresponding to the load carried by the sent PUSCH, the situation that the base station correctly detects the preamble sequence and the load carried by the PUSCH when the UE initiates random access by adopting 2-stepRACH is correspondingly met;

case three: if the response message content corresponding to the first random access message sent by the UE is not the response message content corresponding to the first random access message sent by the UE, for example, the UE waits to receive a response in a response timing time window configured by the system after sending the MsgA, and when the response timing times out, the UE does not receive any response information content corresponding to the MsgA sent by the UE, the UE correspondingly refers to a case that the UE does not correctly detect the preamble sequence and the load carried by the PUSCH when initiating random access by using 2-stepRACH, or a case that the UE does not correctly detect the preamble sequence when initiating random access by using 4-stepRACH, or a case that the UE does not correctly detect the response message sent by the base station and including the response message corresponding to the first random access message sent by the UE.

Therefore, the UE judges whether to reinitiate random access or send a second random access message according to the system random access configuration and the response information detection result;

corresponding to the first situation: UE re-initiates random access according to a random access retransmission mechanism configured by the system;

wherein the UE that is initiating random access using 2-step RACH includes four random access re-initiations: the first is to initiate the preamble sequence of MsgA and the load retransmission of PUSCH bearer using 2-step RACH, the second is to initiate the retransmission of the load of PUSCH bearer only using 2-step RACH, the third is to fallback to 4-step RACH to initiate the transmission of Msg1, and the fourth is to fallback to 4-step RACH to initiate the transmission of Msg 3. And the UE selects the mode to initiate the MsgA retransmission according to the system configuration and the detection result. For example, the UE determines, according to the system configuration, that the received response message content is a response message content corresponding to MsgA sent for itself. If the corresponding response message content contains an uplink grant, then the uplink grant is used to fall back to 4-step RACH to transmit msg3 (the fourth option above is selected). And if the uplink authorization is not contained, selecting one mode of the first mode, the second mode or the third mode to initiate the MsgA retransmission according to the system configuration. And if the corresponding response information content contains TA information, adjusting the sending timing according to the TA in the next information sending.

A UE that is initiating random access using 4-step RACH includes two random access re-initiations and a second random access message transmission: the first method is to initiate a preamble sequence of MsgA and load retransmission carried by PUSCH by using 2-step RACH; the second is to initiate the transmission of Msg1 using a 4-step RACH. The sending of one type of the second random access message indicates initiating a transmission of Msg3 using a 4-step RACH. Wherein the second random access message is Msg 3.

And further, when the UE initiates random access by using the 2-step RACH, selecting a preamble sequence and related transmission resources according to the related configuration of the 2-step RACH, generating a corresponding random access message and the like. And when the UE initiates random access by using the 4-step RACH, selecting a preamble sequence and related transmission resources according to the related configuration of the 4-step RACH, generating a corresponding random access message and the like.

Corresponding to the second case: the UE further judges whether to feed back the confirmation information of the response message received correctly; for example, ACK or NACK information is fed back. And if the corresponding response information content contains TA information, adjusting the sending timing according to the TA in the next information sending.

Corresponding to the third situation: and when the UE does not receive the response message content corresponding to the first random access message sent by the UE in the time window of receiving the response message, the UE reinitiates random access according to a random access retransmission mechanism configured by the system.

The UE that is initiating random access using 2-step RACH includes four types of random access: the first is to initiate the preamble sequence of MsgA and the load retransmission of PUSCH bearer using 2-step RACH, the second is to initiate the retransmission of the load of PUSCH bearer only using 2-step RACH, the third is to fallback to 4-step RACH to initiate the transmission of Msg1, and the fourth is to fallback to 4-step RACH to initiate the transmission of Msg 3. And under the scene that the loads carried by the MsgA preamble sequence and the PUSCH are not correctly detected, the retransmission of the MsgA is selected in the first and third modes.

Based on the same inventive concept, the present invention further provides a user equipment UE, a schematic structural diagram of which is shown in fig. 12, where the UE includes a second receiving module 1201 and a second processing module 1202;

the second receiving module 1201 is configured to detect whether to send a response message content corresponding to the first random access message for the second receiving module after receiving the random access response message; the corresponding response message content includes: RAPID corresponding to the sent preamble sequence and/or response message corresponding to the load carried by the sent PUSCH;

the second processing module 1202 is configured to perform,

the second receiving module 1201 is configured to, when detecting that it is self-sending a response message content corresponding to the first random access message, where the response message content includes a RAPID corresponding to the sent preamble sequence but corresponds to a response message without a load borne by a PUSCH, re-initiate a random access or send a second random access message according to a system configuration random access retransmission mechanism;

the second receiving module 1201 is configured to, when detecting that the response message content corresponding to the first random access message is sent by itself and includes a RAPID corresponding to the sent preamble sequence and a response message corresponding to the sent load carried by the PUSCH, further determine whether to feed back the acknowledgement information of the response message received correctly according to the system configuration;

the UE re-initiates random access according to a system configuration random access retransmission mechanism when the second receiving module 1201 does not receive the response message content corresponding to the first random access message sent by the UE in the system configuration time window for receiving the response message.

As can be seen from the above description, the random access method, the base station, and the user equipment provided in the present invention have the following advantages:

1) the random access response message of the present invention assembles response information of the 2-step RACH and response information of the 4-step RACH into one MAC PDU.

2) The random access response message of the present invention may support multiple retransmissions of a 2-step RACH.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method of random access, the method comprising:

after receiving a first random access message sent by User Equipment (UE), a base station sends a random access response message to the UE and indicates the UE to carry out random access; the first random access message comprises at least one information of Preamble sequence Preamble and load carried by uplink shared channel PUSCH;

the method is characterized in that a media access control protocol data unit (MAC PDU) of the random access response message comprises any one or combination of a plurality of message types of a first response message, a second response message and a third response message, and each response message corresponds to one MAC PDU subunit;

the MAC PDU subunit corresponding to the first response message includes multiple response message formats to support the inclusion of multiple response message contents, and a load in the MAC PDU subunit corresponding to the first response message includes: timing advance information TA, uplink authorization information UL Grant and one or more combinations of fields of a temporary cell radio network temporary identification mark TC-RNTI;

2. The method of claim 1,

the load in the MAC PDU subunit corresponding to the second response message includes: a response message corresponding to the load carried by the PUSCH;

the load in the MAC PDU subunit corresponding to the third response message includes: TA, UL Grant and TC-RNTI fields.

3. The method of claim 1, wherein the random access response message includes bits for distinguishing message types in MAC PDU subunits for different message types.

4. The method of claim 2, wherein when a load in a MAC PDU subunit to which the first response message corresponds includes a timing advance information (TA), an uplink Grant information (UL Grant) and a temporary cell radio network temporary identity (TC-RNTI) field, a field value in which no indication is required is set to zero.

5. The method of claim 1, wherein the format configuration of the MAC PDU of the random access response message is signaled to the UE by the base station in radio resource control, RRC, signaling; or the base station notifies the UE of the information contained in the physical downlink control channel PDCCH; or written in the base station and the UE through the device configuration.

6. The method of claim 1, wherein a two-step random access channel retransmission Backoff Indication (BI) and a four-step random access channel retransmission Backoff Indication (BI) in a MAC PDU of the random access response message are configured commonly or independently from each other.

7. The method of claim 6, wherein the configuring is signaled by a base station to a UE in Radio Resource Control (RRC) signaling; or the base station notifies the UE of the information contained in the physical downlink control channel PDCCH; or written in the base station and the UE through the device configuration.

8. The method of claim 6, wherein the two-step rach retransmission backoff indication BI and the four-step rach retransmission backoff indication BI in the MAC PDU of the random access response message are configured independently, and specifically comprises:

the MAC PDU of the random access response message comprises a first retransmission back-off indication BI and a second retransmission back-off indication BI, and MAC PDU subunits aiming at different BI comprise bits for distinguishing different BI;

the first BI is a two-step random access channel retransmission backoff indication BI and is used for indicating the UE to re-initiate two-step random access by applying the first BI after the random access fails;

and the second BI is a four-step random access channel retransmission backoff indication BI and is used for indicating the UE to re-initiate the four-step random access by applying the second BI after the random access fails.

9. The method of claim 6, wherein the common configuration of the two-step random access channel retransmission backoff indication BI and the four-step random access channel retransmission backoff indication BI in the MAC PDU of the random access response message specifically comprises:

the MAC PDU of the random access response message includes a third retransmission back indication BI, where the third BI is used to indicate the UE to reinitiate the two-step random access or the four-step random access after the random access fails.

10. The method of claim 1,

if the content of the response message corresponding to the first random access message is sent by the UE, wherein the content of the response message comprises a RAPID corresponding to the sent leader sequence, but the response message does not correspond to the load carried by the sent PUSCH, the UE reinitiates random access or sends a second random access message according to a system configuration random access retransmission mechanism;

if the response message content corresponding to the first random access message is sent by the UE, wherein the response message content comprises a RAPID corresponding to the sent leader sequence and a response message corresponding to the sent load carried by the PUSCH, the UE further judges whether to feed back confirmation information of correctly receiving the response message according to system configuration;

and if the response message content corresponding to the first random access message sent by the UE is not received in the response message receiving time window configured by the system, the UE re-initiates random access according to a random access retransmission mechanism configured by the system.

11. A base station is characterized in that the base station comprises a first receiving module, a first processing module and a sending module;