CN111526597B

CN111526597B - Two-step random access method, equipment and device

Info

Publication number: CN111526597B
Application number: CN201910103083.XA
Authority: CN
Inventors: 谌丽
Original assignee: Datang Mobile Communications Equipment Co Ltd
Current assignee: Datang Mobile Communications Equipment Co Ltd
Priority date: 2019-02-01
Filing date: 2019-02-01
Publication date: 2023-04-18
Anticipated expiration: 2039-02-01
Also published as: CN111526597A

Abstract

The invention discloses a two-step random access method, equipment and a device, comprising the following steps: receiving a random access request msgA sent by connected user equipment, wherein the msgA comprises a random access lead code and transmission on a physical uplink shared channel; sending a physical downlink control channel command scrambled by a cell radio network temporary identifier of the user equipment to the user equipment, wherein the physical downlink control channel command is used for scheduling downlink transmission resources to the user equipment; and sending a timing advance command on downlink transmission resources scheduled for the user equipment to allow the user equipment to perform uplink synchronous adjustment. The invention can ensure the quick completion of two-step random access competition solution, saves transmission resources and reduces the risk of competition solution failure.

Description

Two-step random access method, equipment and device

Technical Field

The present invention relates to the field of wireless communications technologies, and in particular, to a two-step random access method, device, and apparatus.

Background

Random access of LTE (Long Term Evolution) and NR (New Radio) systems is classified into two types, namely contention random access and non-contention random access. The process is as follows:

fig. 1 is a schematic diagram of a contention Random Access procedure, which is mainly divided into four steps as shown in the figure, and is called 4-step RACH (Random Access Channel):

msg1: a UE (User Equipment, i.e. a terminal) selects a Random Access preamble and a PRACH (Physical Random Access Channel) resource and transmits the selected Random Access preamble to a base station by using the PRACH resource.

Msg2: and the base station receives the preamble and sends a random access response. The random access response contains two parts: a MAC (Media Access Control) header and a MAC RAR (Random Access Response). The MAC header includes a plurality of sub-headers, whose main contents are RAPID (Random Access Preamble ID) and Backoff parameter BI (Backoff Indicator), and fig. 2 is a schematic diagram of the MAC sub-header with RAPID. Fig. 3 is a schematic diagram of a MAC RAR, which includes a timing Advance TAC (Time Advance Command), an uplink resource Grant (UL Grant) for Msg3, and a temporal C-RNTI (Temporary C-RNTI; C-RNTI: cell-Radio Network temporal identity) allocated by a Network side. A Physical Downlink Control Channel (PDCCH) carrying the Msg2 scheduling information is scrambled by using a Random Access-Radio Network Temporary Identity (RA-RNTI), and the RA-RNTI uniquely corresponds to a time-frequency resource for transmitting the Msg1 within a window length of receiving the Msg2 by the UE. When receiving the Msg2, the UE determines that the Msg2 corresponds to the Msg1 transmitted by the UE through the RA-RNTI and the preamble ID.

Msg3: the UE sends uplink transmission on the UL grant specified by the Msg2, the uplink transmission content of the Msg3 is different due to different random access reasons, for example, for initial access, the Msg3 transmits an RRC (Radio Resource Control) connection establishment request, and the connected UE sends C-RNTI MAC CE (Control Element) in the Msg 3.

Msg4: and (5) the UE can judge whether the random access is successful according to the Msg 4. For idle UE (idle UE) or inactive UE (inactive UE), msg4 carries CCCH (Common Control Channel) MAC CE corresponding to RRC signaling of Msg3, and for connected UE, msg4 performs contention resolution by using PDCCH with unique C-RNTI in the UE cell. For idle UE or inactive UE, after the competition resolving succeeds, the temporary C-RNTI is converted into the unique UE identity C-RNTI of the UE in the cell.

Fig. 4 is a schematic diagram of a non-contention random access process, where the non-contention random access process is mainly divided into three steps as shown in the figure:

msg0: and the base station allocates a special preamble for non-competitive random access and PRACH resources used by the random access to the UE.

Msg1: and the UE sends the appointed special preamble to the base station on the appointed PRACH resource according to the indication of the Msg 0. And after receiving the Msg1, the base station calculates an uplink TA (Timing Advance) according to the Msg 1.

Msg2: and the base station sends a random access response to the UE, wherein the random access response comprises timing advance information and a subsequent uplink transmission resource allocation (UL grant), and the timing advance is used for the timing relation of the subsequent uplink transmission of the UE.

In the new generation of the wireless network NR system, a two-step Random access procedure (2-step RACH) is introduced based on the 4-step RACH (Random access), and fig. 5 is a schematic diagram of the 2-step RACH access procedure, and the procedure is shown in the figure. The 2-step RACH is a contention random access and needs to complete contention resolution. The most primitive way is that msgA contains the contents of Msg1 and Msg3 of 4-step RACH, and msgB contains the contents of Msg2 and Msg4 of 4-step RACH.

The prior art is disadvantageous in that the introduction of a two-step random access 2-step RACH in a 5G system causes resource waste and contention resolution delay.

Disclosure of Invention

The invention provides a two-step random access method, equipment and a device, which are used for solving the problems of resource waste and contention resolution delay in a 2-step RACH.

The embodiment of the invention provides a two-step random access method, which comprises the following steps:

receiving a random access request msgA sent by connected UE, wherein the msgA comprises preamble and transmission on PUSCH;

sending a PDCCH command scrambled by the C-RNTI of the UE to the UE, wherein the PDCCH command is used for scheduling downlink transmission resources to the UE;

and sending TAC on downlink transmission resources scheduled for the UE to perform uplink synchronous adjustment.

In an implementation, the TAC is carried by a TAC MAC CE, or carried by a MAC RAR PDU.

In implementation, the MAC RAR PDU carries an uplink resource allocation UL grant.

In the implementation, after the contention resolution is completed, the method further includes:

and sending a PDCCH order scrambled by the C-RNTI of the UE to the UE, wherein the PDCCH order is used for scheduling uplink transmission resources to the UE.

the method comprises the steps that connected UE sends a random access request msgA to a base station, wherein the msgA comprises preamble and transmission on a PUSCH;

receiving a PDCCH command scrambled by the C-RNTI of the UE by a base station, wherein the PDCCH command is used for scheduling downlink transmission resources to the UE;

and receiving the TAC sent by the base station on the scheduled downlink transmission resource, and performing uplink synchronization adjustment according to the TAC.

In implementation, the MAC RAR PDU carries a UL grant.

In implementation, after completing the contention resolution, the method further includes:

and receiving a PDCCH command which is scrambled by the C-RNTI of the UE and is sent to the UE by a base station, wherein the PDCCH command is used for scheduling uplink transmission resources to the UE.

In an implementation, after transmitting msgA to the base station, the method further includes:

starting a random access response receiving timer;

and receiving the random access response of the base station within the effective time period of the random access response receiving timer, and if the random access response receiving timer is overtime, considering that the random access attempt fails.

In practice, the timer is started after one of the following times: after transmitting the preamble, after transmitting the PUSCH of msgA, after a fixed time interval after transmitting the preamble, after a fixed time interval after transmitting the PUSCH of msgA.

In implementation, the receiving, by the terminal, the random access response of the base station includes:

when the TAC is carried by the TAC MAC CE, if the timer is T0:

if the downlink transmission scheduled by the PDCCH command scrambled by the C-RNTI and the TAC MAC CE sent on the downlink transmission are received before the T0 is overtime, the completion of contention resolution is determined, and the random access process is ended; or the like, or, alternatively,

if the MAC RAR scheduled by the PDCCH order scrambled by the RA-RNTI is received before T0 timeout, determining that the backspacing from the 2-step RACH to the 4-step RACH occurs, and executing a 4-step RACH process based on contention; or the like, or, alternatively,

if T0 is overtime, the random access attempt is determined to fail, resources are reselected to transmit msgA of 2-step RACH or Msg1 of 4-step RACH, if the maximum random access times are not successful, the random access failure is determined to occur, and the random access failure is reported to a high layer; or the like, or, alternatively,

if T0 is overtime and the Msg2 window length of the 4-step RACH is also overtime, the random access attempt is determined to fail, resources are reselected to send msgA of the 2-step RACH or Msg1 of the 4-step RACH, if the maximum random access times are not successful, the random access failure is determined to occur, and a high level is reported.

when the TAC is carried by the MAC RAR PDU, the timer is T1, and then:

if the downlink transmission scheduled by the PDCCH command scrambled by the C-RNTI and the MAC RAR PDU sent on the downlink transmission are received before T1 is overtime, the completion of contention resolution is determined, and the random access process is ended; or the like, or, alternatively,

if the MAC RAR scheduled by the PDCCH order scrambled by the RA-RNTI is received before T1 timeout, determining that the backspacing from the 2-step RACH to the 4-step RACH occurs, and executing a 4-step RACH process based on contention; or the like, or, alternatively,

if T1 is overtime, the random access attempt is determined to fail, resources are reselected to transmit msgA of 2-step RACH or Msg1 of 4-step RACH, if the maximum random access times are not successful, the random access failure is determined to occur, and the random access failure is reported to a high layer; or the like, or, alternatively,

if T1 is overtime and the Msg2 window length of the 4-step RACH is also overtime, the random access attempt is determined to fail, resources are reselected to send msgA of the 2-step RACH or Msg1 of the 4-step RACH, if the maximum random access times are not successful, the random access failure is determined to occur, and a high level is reported.

In an implementation, T1 is implemented by multiplexing the Msg2 window length.

An embodiment of the present invention provides a base station, where the base station includes:

a processor for reading the program in the memory, performing the following processes:

sending TAC on downlink transmission resources scheduled for the UE for uplink synchronization adjustment of the UE;

a transceiver for receiving and transmitting data under the control of the processor.

In implementation, the TAC is carried by a TAC MAC CE, or carried by a MAC RAR PDU.

An embodiment of the present invention provides a user equipment, where the user equipment includes:

receiving a TAC sent by the base station on the scheduled downlink transmission resource, and performing uplink synchronization adjustment according to the TAC;

In implementation, the MAC RAR PDU carries a UL grant.

and receiving a PDCCH command which is transmitted to the UE by the base station and scrambled by the C-RNTI of the UE, wherein the PDCCH command is used for scheduling uplink transmission resources to the UE.

starting a random access response receiving timer;

when the TAC is carried by the TAC MAC CE, if the timer is T0:

if the MAC RAR scheduled by the PDCCH order scrambled by the RA-RNTI is received before T0 timeout, determining that the backspacing from 2-step RACH to 4-step RACH occurs, and executing a 4-step RACH process based on competition; or the like, or, alternatively,

if T0 is overtime, determining that the random access attempt fails, reselecting resources to send msgA of 2-step RACH or Msg1 of 4-step RACH, if the maximum random access times are not successful, determining that the random access fails, and reporting to a high layer; or the like, or, alternatively,

when the TAC is carried by the MAC RAR PDU, the timer is T1, and then:

if the downlink transmission scheduled by the PDCCH command scrambled by the C-RNTI and the MAC RAR PDU sent on the downlink transmission are received before T1 is overtime, the completion of contention resolution is determined, and the random access process is ended; or the like, or a combination thereof,

if the MAC RAR scheduled by the PDCCH order scrambled by the RA-RNTI is received before T1 timeout, determining that the backspacing from 2-step RACH to 4-step RACH occurs, and executing a 4-step RACH process based on competition; or the like, or, alternatively,

In an implementation, T1 is implemented by multiplexing the Msg2 window length.

The embodiment of the invention provides a two-step random access device, which comprises:

a base station receiving module, configured to receive a random access request msgA sent by a connected UE, where the msgA includes a preamble and transmission on a PUSCH;

a base station sending module, configured to send, to the UE, a PDCCH order scrambled with the C-RNTI of the UE, where the PDCCH order is used to schedule downlink transmission resources to the UE; and sending TAC on downlink transmission resources scheduled for the UE to perform uplink synchronous adjustment.

a terminal sending module, configured to send a random access request msgA to a base station on a connected UE, where the msgA includes a preamble and transmission on a PUSCH;

a terminal receiving module, configured to receive a PDCCH order scrambled by the C-RNTI of the UE by a base station, where the PDCCH order is used to schedule downlink transmission resources to the UE; and receiving the TAC sent by the base station on the scheduled downlink transmission resource, and performing uplink synchronization adjustment according to the TAC.

An embodiment of the present invention provides a computer-readable storage medium, where a computer program for executing the two-step random access method is stored in the computer-readable storage medium.

The invention has the following beneficial effects:

in the technical scheme provided by the embodiment of the invention, after msgA sent by connected UE is received, the base station sends a PDCCH command scrambled by C-RNTI to the UE, so that the UE can determine downlink transmission scheduling resources, and then sends TAC on the resources, so that the UE can perform uplink synchronous adjustment.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a diagram illustrating a contention random access process in the background art;

FIG. 2 is a diagram of a MAC subheader with RAPID in the background art;

FIG. 3 is a diagram of a MAC RAR in the background art;

FIG. 4 is a diagram illustrating a non-contention random access procedure in the background art;

FIG. 5 is a diagram illustrating a 2-step RACH access procedure in the background art;

fig. 6 is a schematic flow chart of an implementation of a two-step random access method at a base station side in an embodiment of the present invention;

fig. 7 is a schematic flow chart of an implementation of a two-step random access method on a UE side in an embodiment of the present invention;

fig. 8 is a schematic diagram of a TAC MAC CE format in the embodiment of the present invention;

FIG. 9 is a diagram of a MAC RAR PDU format according to an embodiment of the present invention;

FIG. 10 is a diagram illustrating a base station structure according to an embodiment of the present invention;

fig. 11 is a schematic diagram of a UE structure according to an embodiment of the present invention.

Detailed Description

The inventor notices in the process of invention that:

two-step random access 2-step RACH is introduced into a 5G system, and if the contents of the existing Msg2 and Msg4 are simply and completely put into the msgB, resource waste and competition resolving delay can be caused. For example, for a connected UE, msg2 is a downlink PDSCH scheduled by a PDCCH scrambled by an RA-RNTI, the PDSCH includes a MAC RAR, msg4 is a transmission scheduled by a PDCCH scrambled by a C-RNTI, and if the two are simply superimposed, msgB needs to include two scheduling commands and two transmissions, and all transmissions must be successfully received to achieve contention resolution. This causes resource waste, increases the risk of failure of contention resolution, and delays the time to complete contention resolution.

Based on this, the technical scheme provided by the embodiment of the invention can solve how to quickly complete the contention resolution of two-step random access in a new generation wireless communication system (NR system or 5G system), ensure that the terminal quickly establishes synchronization with the network and performs data transmission, and simultaneously save network resources. The following describes embodiments of the present invention with reference to the drawings.

In the description process, the implementation of the UE and the base station will be described separately, and then an example of the implementation of the UE and the base station in cooperation will be given to better understand the implementation of the scheme given in the embodiment of the present invention. Such an explanation does not mean that the two must be implemented together or separately, and actually, when the UE and the base station are implemented separately, the UE and the base station solve the problems on the UE side and the base station side, respectively, and when the two are used in combination, a better technical effect is obtained.

Fig. 6 is a schematic flow chart of an implementation process of a two-step random access method on a base station side, as shown in the figure, the two-step random access method may include:

601, receiving msgA sent by connected UE, wherein the msgA comprises preamble and transmission on PUSCH;

step 602, sending a PDCCH order scrambled by the C-RNTI of the UE to the UE, wherein the PDCCH order is used for scheduling downlink transmission resources to the UE;

step 603, sending TAC on the downlink transmission resource scheduled for the UE for uplink synchronization adjustment of the UE.

Fig. 7 is a schematic flowchart of an implementation process of a two-step random access method on a UE side, which may include:

step 701, the connected UE sends msgA to the base station, where the msgA includes preamble and transmission on PUSCH;

step 702, receiving a PDCCH order scrambled by a C-RNTI of the UE by a base station, wherein the PDCCH order is used for scheduling downlink transmission resources to the UE;

step 703, receiving the TAC sent by the base station on the scheduled downlink transmission resource, and performing uplink synchronization adjustment according to the TAC.

In specific implementation, for 2-step RACH, for connected UE, a base station schedules downlink transmission through a PDCCH with a C-RNTI, and the downlink transmission carries TAC, so that contention resolution is completed.

In the implementation, the TAC is carried by a TAC MAC CE, or carried by a MAC RAR PDU (MAC random access response Protocol Data Unit, PDU: protocol Data Unit).

The following description will be made separately.

Mode 1: the TAC is carried over the TAC MAC CE.

The base station schedules downlink transmission resources by using the PDCCH with the C-RNTI, and transmits TAC MAC CE (Timing advanced Command MAC CE) in the scheduled downlink transmission resources.

In the implementation, after the contention resolution is completed, the method may further include:

and transmitting a PDCCH order scrambled by the C-RNTI of the UE to the UE, wherein the PDCCH order is used for scheduling uplink transmission resources to the UE.

Correspondingly, after the UE completes contention resolution, the method further includes:

That is, after the base station sends the TAC MAC CE and completes contention resolution, the base station may allocate uplink transmission resources to the UE by using the scheduling command PDCCH.

The TAC MAC CE may adopt the prior art, and fig. 8 is a schematic diagram of a format of the TAC MAC CE, where the format is shown in the figure.

In the implementation, a transmission success guarantee mechanism may also be added, that is, after the msgA is sent to the base station, the method may further include:

starting a random access response receiving timer;

and receiving the random access response of the base station in the effective time period of the random access response receiving timer, and if the random access response receiving timer is overtime, determining that the random access attempt fails.

In practice, the timer is started after one of the following times: after transmitting preamble, after transmitting PUSCH of msgA, after a fixed time interval after transmitting preamble, after transmitting terminal id on PUSCH of msgA.

when the TAC is carried by the TAC MAC CE, if the timer is T0:

if the downlink transmission scheduled by the PDCCH command scrambled by the C-RNTI and the TAC MAC CE sent on the downlink transmission are received before the T0 is overtime, the completion of contention resolution is determined, and the random access process is ended; or, the PDCCH is scrambled with the C-RNTI (PDCCH with C-RNTI); or the like, or, alternatively,

if T0 is overtime, the random access attempt is determined to fail, resources are reselected to transmit msgA of 2-step RACH or Msg1 of 4-step RACH, if the maximum random access times are not successful, the random access failure is determined to occur, and the random access failure is reported to a high layer; or the like, or a combination thereof,

Specifically, after the terminal transmits msgA, a timer T0 is started, and a response to msgA transmitted by the base station is received before the timer expires. Specifically, after the preamble is sent, or after the PUSCH of msgA is sent, or after a fixed time interval after the preamble is sent, or after the fixed time interval of the PUSCH of msgA is sent, the timer T0 is started.

If the downlink transmission scheduled by the PDCCH with the C-RNTI and the TAC MAC CE sent on the downlink transmission are received before the T0 is overtime, the completion of the contention resolution is determined, and the random access process is ended; or the like, or a combination thereof,

if the MAC RAR scheduled by the PDCCH scrambled by the RA-RNTI is received before T0 timeout, determining that the backspacing from the 2-step RACH to the 4-step RACH occurs, and executing a 4-step RACH process based on contention; or the like, or, alternatively,

Mode 2: the TAC is carried over MAC RAR PDUs.

In implementation, in addition to TAC, the MAC RAR PDU carries UL grant.

A base station schedules downlink transmission resources by using a PDCCH with a C-RNTI, and sends a MAC RAR PDU (MAC random access response protocol data unit) in the scheduled downlink transmission resources, where the MAC RAR at least carries a TAC and a UL grant, and the MAC RAR PDU may adopt the existing technology, and fig. 9 is a schematic diagram of a format of the MAC RAR PDU, where the format is shown in the figure, and may or may not carry the temporary C-RNTI.

In implementation, a transmission success guarantee mechanism may also be added, that is, after msgA is sent to the base station, the method may further include:

starting a random access response receiving timer;

In practice, the timer is started after one of the following times: after the preamble is transmitted, after the PUSCH of msgA is transmitted, after a fixed time interval after the preamble is transmitted, after a fixed time interval after the PUSCH of msgA is transmitted.

when the TAC is carried by the MAC RAR PDU, the timer is T1, and then:

if T1 is overtime, determining that the random access attempt fails, reselecting resources to send msgA of 2-step RACH or Msg1 of 4-step RACH, if the maximum random access times are not successful, determining that the random access fails, and reporting to a high layer; or the like, or, alternatively,

if T1 is overtime and the Msg2 window length of the 4-step RACH is overtime, determining that the random access attempt fails, reselecting a resource to send msgA of the 2-step RACH or Msg1 of the 4-step RACH, if the maximum random access times are not successful, determining that the random access fails, and reporting the high-level TAC.

In an implementation, T1 is implemented by multiplexing the Msg2 window length.

Specifically, after the terminal transmits msgA, a timer T1 is started, and a response to msgA sent by the base station is received before the timer expires, and the timer T1 may multiplex the Msg2 window length. Specifically, after preamble is sent, after PUSCH of msgA is sent, after a fixed time interval after preamble is sent, after PUSCH of msgA is sent, after the fixed time interval of PUSCH of msgA is sent, timer T1 is started.

If receiving downlink transmission scheduled by a PDCCH with a C-RNTI and MAC RAR PDU sent on the downlink transmission before T1 overtime, determining to finish contention resolution and ending the random access process; or the like, or a combination thereof,

if the MAC RAR scheduled by the PDCCH scrambled by the RA-RNTI is received before T1 timeout, determining that the backspacing from the 2-step RACH to the 4-step RACH occurs, and executing a 4-step RACH process based on contention; or the like, or a combination thereof,

The following is also illustrated by way of example.

Example 1:

in this example, the base station sends TAC MAC CE.

A terminal side:

1: the terminal sends a preamble code on the msgA resource configured by the base station and sends a terminal identifier on the PUSCH;

2: a terminal receives a PDCCH command scrambled by a base station by using a C-RNTI (radio network temporary identifier), and determines downlink transmission scheduling resource allocation;

3: a terminal receives a TAC MAC CE sent by a base station and carries out uplink synchronization adjustment;

4: and after completing the contention resolution, the terminal receives the uplink resource allocation of the base station and sends uplink transmission on the uplink resource allocation. In practice, this step is optional.

A base station side:

1: a base station receives msgA sent by a terminal, wherein the msgA comprises preamble codes and a terminal identifier (the terminal identifier can be C-RNTI MAC CE) sent by the terminal on a PUSCH;

2: the base station scrambles PDCCH by using C-RNTI and schedules PDSCH resources for the terminal;

3: the base station sends TAC MAC CE in the scheduled PDSCH resource to realize uplink synchronization of the terminal;

4: and after completing the contention resolution, the base station allocates uplink transmission resources for the terminal scheduling. In practice, this step is optional.

Example 2:

in this example, the base station sends a MAC RAR.

A terminal side:

3: and the terminal receives the MAC RAR sent by the base station, performs uplink synchronization adjustment and sends uplink transmission on UL grant allocation resources of the MAC RAR.

A base station side:

1: a base station receives msgA sent by a terminal, wherein the msgA comprises a preamble code and a terminal identifier sent by the terminal on a PUSCH (the terminal identifier can be C-RNTI MAC CE);

3: and the base station sends MAC RAR PDU in the scheduled PDSCH resource, wherein the MAC RAR at least comprises TAC and UL grant.

Example 3:

in this example, the base station sends TAC MAC CE, and adds a random access transmission guarantee mechanism.

A terminal side:

after the terminal transmits msgA, a timer T0 is started, and a response to msgA transmitted by the base station is received before the timer times out. Specifically, after the preamble is sent, or the PUSCH is sent, or after a fixed time interval after the preamble is sent, or after the fixed time interval after the PUSCH is sent, the timer T0 is started.

If the downlink transmission scheduled by the PDCCH with the C-RNTI and the TAC MAC CE sent on the downlink transmission are received before the T0 is overtime, the completion of the contention resolution is determined, and the random access process is ended; or the like, or, alternatively,

A base station side:

and after receiving the msgA, starting a timer T0, wherein the specific starting time corresponds to the starting time of the terminal side. And sending a response according to the received msgA condition.

And if preamble codes and PUSCH transmission are received, sending downlink transmission scheduled by the PDCCH with the C-RNTI, and sending TAC MAC CE on the downlink transmission. The downlink transmission supports an HARQ retransmission process.

If only preamble is received, it is considered as a general 4-step RACH, and Msg2 is recovered within the Msg2 window length.

Example 4:

in this example, the base station sends the MAC RAR and adds a random access transmission guarantee mechanism.

A terminal side:

after the terminal sends msgA, a timer T1 is started, and a response to msgA sent by the base station is received before the timer expires, and the timer T1 may multiplex the Msg2 window length. Specifically, after the preamble is sent, or the PUSCH is sent, or after a fixed time interval after the preamble is sent, or after the fixed time interval after the preamble is sent, the timer T1 is started.

If the downlink transmission scheduled by the PDCCH with the C-RNTI and the MAC RAR PDU sent on the downlink transmission are received before T1 is overtime, the completion of contention resolution is determined, and the random access process is ended; or the like, or, alternatively,

if T1 is overtime, determining that the random access attempt fails, reselecting resources to send msgA of 2-step RACH or Msg1 of 4-step RACH, if the maximum random access times are not successful, determining that the random access fails, and reporting to a high layer;

or if T1 is overtime and the Msg2 window length of the 4-step RACH is also overtime, determining that the random access attempt fails, reselecting resources to send msgA of the 2-step RACH or Msg1 of the 4-step RACH, if the maximum random access times are not successful, determining that the random access fails, and reporting to a high layer.

A base station side:

after receiving msgA, starting a timer T1, where the specific starting time corresponds to the starting time of the terminal side. And sending a response according to the received msgA condition.

And if preamble codes and PUSCH transmission are received, sending downlink transmission of PDCCH scheduling with C-RNTI, and sending MAC RAR on the downlink transmission. The downlink transmission does not support the HARQ retransmission process. The base station determines whether the MAC RAR is successfully sent or not by whether the terminal sends uplink transmission on the resources allocated by the UL grant of the MAC RAR or not.

If only preamble is received, it is considered as a normal 4-step RACH, and Msg2 is replied within the Msg2 window length.

Based on the same inventive concept, the embodiment of the present invention further provides a base station, a user equipment, and a two-step random access apparatus, and because the principles and methods for solving the problems of these apparatuses are similar, the implementation of these apparatuses can refer to the implementation of the two-step random access method, and the repeated parts are not described again.

When the technical scheme provided by the embodiment of the invention is implemented, the implementation can be carried out as follows.

Fig. 10 is a schematic structural diagram of a base station, as shown in the figure, the base station includes:

the processor 1000, which is used to read the program in the memory 1020, executes the following processes:

receiving a random access request msgA sent by UE in a connected state, wherein the msgA comprises preamble and transmission on PUSCH;

a transceiver 1010 for receiving and transmitting data under the control of the processor 1000.

Where in fig. 10, the bus architecture may include any number of interconnected buses and bridges, with various circuits being linked together, particularly one or more processors represented by processor 1000 and memory represented by memory 1020. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. The bus interface provides an interface. The transceiver 1010 may be a number of elements including a transmitter and a transceiver providing a means for communicating with various other apparatus over a transmission medium. The processor 1000 is responsible for managing the bus architecture and general processing, and the memory 1020 may store data used by the processor 1000 in performing operations.

Fig. 11 is a schematic structural diagram of a UE, and as shown in the figure, the UE includes:

the processor 1100, which reads the program in the memory 1120, performs the following processes:

a transceiver 1110 for receiving and transmitting data under the control of the processor 1100.

In implementation, the MAC RAR PDU carries a UL grant.

In the implementation, after transmitting msgA to the base station, the method further includes:

starting a random access response receiving timer;

when the TAC is carried by the TAC MAC CE, if the timer is T0:

if the downlink transmission scheduled by the PDCCH command scrambled by the C-RNTI and the TAC MAC CE transmitted on the downlink transmission are received before T0 is overtime, determining to finish contention resolution, and ending the random access process; or the like, or, alternatively,

when the TAC is carried by the MAC RAR PDU, the timer is T1, and then:

if the MAC RAR scheduled by the PDCCH order scrambled by the RA-RNTI is received before T1 timeout, determining that the backspacing from the 2-step RACH to the 4-step RACH occurs, and executing a 4-step RACH process based on contention; or the like, or a combination thereof,

In an implementation, T1 is implemented by multiplexing the Msg2 window length.

Where in fig. 11, the bus architecture may include any number of interconnected buses and bridges, with one or more processors, represented by processor 1100, and various circuits, represented by memory 1120, being linked together. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. The bus interface provides an interface. The transceiver 1110 may be a number of elements including a transmitter and a receiver that provide a means for communicating with various other apparatus over a transmission medium. For different user devices, the user interface 1130 may also be an interface capable of interfacing with a desired device, including but not limited to a keypad, display, speaker, microphone, joystick, etc.

The processor 1100 is responsible for managing the bus architecture and general processing, and the memory 1120 may store data used by the processor 1100 in performing operations.

a base station sending module, configured to send, to the UE, a PDCCH order scrambled with the C-RNTI of the UE, where the PDCCH order is used to schedule downlink transmission resources to the UE; and sending TAC on downlink transmission resources scheduled for the UE for uplink synchronous adjustment of the UE.

An embodiment of the present invention provides a computer-readable storage medium, which is characterized in that the computer-readable storage medium stores a computer program for executing the two-step random access method.

For convenience of description, each part of the above-described apparatus is separately described as being functionally divided into various modules or units. Of course, the functionality of the various modules or units may be implemented in the same one or more pieces of software or hardware in practicing the invention.

In summary, in the technical solution provided in the embodiment of the present invention, for a 2-step RACH, for a connected UE, a base station schedules downlink transmission through a PDCCH with a C-RNTI, where TAC is carried in the downlink transmission, so as to complete contention resolution.

The embodiment provides that the base station schedules downlink transmission resources by using a PDCCH with a C-RNTI (radio network temporary identifier), and sends the TAC MAC CE in the scheduled downlink transmission resources. And the base station uses the PDCCH with the C-RNTI to schedule downlink transmission resources, and sends MAC RAR PDU in the scheduled downlink transmission resources, wherein the MAC RAR at least carries TAC and UL grant.

Further provides an implementation scheme under a transmission success guarantee mechanism.

By adopting the scheme, the 2-step RACH competition solution can be rapidly completed, the transmission resource is saved, and the risk of the competition solution failure is reduced.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A two-step random access method, comprising:

receiving a random access request msgA sent by connected User Equipment (UE), wherein the msgA comprises a random access preamble and transmission on a Physical Uplink Shared Channel (PUSCH);

sending a Physical Downlink Control Channel (PDCCH) command scrambled by a cell radio network temporary identifier (C-RNTI) of the UE to the UE, wherein the PDCCH command is used for scheduling downlink transmission resources to the UE;

sending a timing advance command TAC on downlink transmission resources scheduled for UE, wherein the TAC is carried by a timing advance command MAC control unit TAC MAC CE, or carried by an MAC random access response protocol data unit MAC RAR PDU, and the TAC is used for completing contention resolution.

2. The method of claim 1, wherein the MAC RAR PDU carries an uplink resource allocation UL grant.

3. The method of any of claims 1 to 2, wherein after completing contention resolution, further comprising:

4. A two-step random access method, comprising:

and receiving a TAC sent by the base station on the scheduled downlink transmission resource, and performing uplink synchronization adjustment according to the TAC, wherein the TAC is carried by a TAC MAC CE, or carried by an MAC RAR PDU, and the TAC is used for completing contention resolution.

5. The method of claim 4, wherein the MAC RAR PDU carries a UL grant.

6. The method of claim 4, wherein upon completion of contention resolution, further comprising:

7. The method of any of claims 4 to 6, wherein after transmitting msgA to the base station, further comprising:

starting a random access response receiving timer;

8. The method of claim 7, wherein the timer is started after one of: after the preamble is transmitted, after the PUSCH of msgA is transmitted, after a fixed time interval after the preamble is transmitted, after a fixed time interval after the PUSCH of msgA is transmitted.

9. The method of claim 7, wherein the terminal receiving the random access response of the base station comprises:

when the TAC is carried by the TAC MAC CE, if the timer is T0:

if the MAC RAR scheduled by the PDCCH command scrambled by the RA-RNTI is received before T0 is overtime, determining that the backspacing from the two-step random access 2-step RACH to the 4-step random access 4-step RACH occurs, and executing a 4-step RACH process based on competition; or the like, or, alternatively,

10. The method of claim 7, wherein the terminal receiving the random access response of the base station comprises:

when the TAC is carried by the MAC RAR PDU, the timer is T1, and then:

11. The method of claim 10, wherein T1 is implemented by multiplexing Msg2 window lengths.

12. A base station, comprising:

sending a TAC on downlink transmission resources scheduled for UE, wherein the TAC is carried by a TAC MAC CE or carried by an MAC RAR PDU and is used for completing contention resolution;

13. The base station of claim 12, wherein the MAC RAR PDU carries an uplink resource allocation UL grant.

14. The base station of any of claims 12 to 13, further comprising, after completing contention resolution:

15. A user equipment, characterized in that the user equipment comprises:

receiving a TAC (random access control) sent by a base station on the scheduled downlink transmission resource, and performing uplink synchronization adjustment according to the TAC, wherein the TAC is carried by a TAC MAC CE (media access control center), or carried by an MAC RAR PDU (media access control center), and the TAC is used for completing contention resolution;

16. The apparatus of claim 15, wherein the MAC RAR PDU carries a UL grant.

17. The apparatus of claim 15, wherein after completing contention resolution, further comprising:

18. The apparatus of any of claims 15 to 17, wherein after transmitting msgA to the base station, further comprising:

starting a random access response receiving timer;

19. The apparatus of claim 18, wherein the timer starts after one of: after the preamble is transmitted, after the PUSCH of msgA is transmitted, after a fixed time interval after the preamble is transmitted, after a fixed time interval after the PUSCH of msgA is transmitted.

20. The apparatus of claim 18, wherein the terminal receives a random access response of the base station, comprising:

when the TAC is carried by the TAC MAC CE, if the timer is T0:

if the downlink transmission scheduled by the PDCCH command scrambled by the C-RNTI and the TAC MAC CE transmitted on the downlink transmission are received before T0 is overtime, determining to finish contention resolution, and ending the random access process; or the like, or a combination thereof,

21. The apparatus of claim 18, wherein the terminal receives a random access response of the base station, comprising:

when the TAC is carried by the MAC RAR PDU, the timer is T1, and then:

22. The apparatus of claim 21, wherein T1 is implemented by multiplexing Msg2 window lengths.

23. A two-step random access apparatus, comprising:

a base station sending module, configured to send, to the UE, a PDCCH order scrambled with the C-RNTI of the UE, where the PDCCH order is used to schedule downlink transmission resources to the UE; sending a TAC on downlink transmission resources scheduled for the UE, wherein the TAC is carried by a timing advance command MAC control unit TAC MAC CE or a MAC random access response protocol data unit MAC RAR PDU, and the TAC is used for completing contention resolution.

24. A two-step random access apparatus, comprising:

a terminal receiving module, configured to receive a PDCCH order scrambled by the C-RNTI of the UE by a base station, where the PDCCH order is used to schedule downlink transmission resources to the UE; and receiving a TAC sent by the base station on the scheduled downlink transmission resource, and performing uplink synchronization adjustment according to the TAC, wherein the TAC is carried by a timing advance command MAC control unit TAC MAC CE, or carried by an MAC random access response protocol data unit MAC RAR PDU, and the TAC is used for completing contention resolution.

25. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program for performing the method of any of claims 1 to 11, which computer program, when being executed by a processor, carries out the method steps of any of claims 1 to 11.