Random access method, apparatus, and storage medium
This application provides a random access method. In the method, a terminal device receives first DCI from a network device. The first DCI includes the first indication information, where the first indication information is used to indicate the type of the response information carried on a PDSCH. The PDSCH carries response information for a random access request initiated by the terminal device. If determining that the type of the response information as indicated by the first indication information matches the random access type of the random access request initiated by the terminal device, the terminal device demodulates the PDSCH indicated by the first DCI. In this way, the terminal device demodulates the PDSCH indicated by the first DCI only when determining, based on the first indication information, that the PDSCH indicated by the received first DCI may belong to the terminal device.
1 . A random access method, comprising:
sending, by a communications apparatus, a random access request to a network device, wherein the random access request comprises a preamble and uplink data;
receiving, by the communications apparatus, first downlink control information (DCI), wherein the first DCI comprises first indication information that indicates a type of response that a physical downlink shared channel (PDSCH) carries;
receiving, by the communications apparatus, a message comprising response information for the random access request, wherein the response information is carried on the PDSCH; and
when the type of the response indicated by the first indication information in the DCI matches a type of the random access request, demodulating, by the communication apparatus, the PDSCH, wherein:
the response information is sent after the uplink data is successfully decoded by the network device,
the response information comprises a contention resolution identity and first information, and
the first information comprises information indicating a resource used to feed back an acknowledgement message and a transmit power control (TPC) command, wherein the information indicating the resource used to feed back the acknowledgement message is for determining a time-frequency resource of a physical uplink control channel (PUCCH) that carries the acknowledgement message, and the TPC command indicates a power control adjustment factor for determining transmit power of the PUCCH.
2 . The method according to claim 1 , wherein the response information further comprises at least one of a cell radio network temporary identifier (C-RNTI) or a timing advance command.
3 . The method according to claim 1 , wherein the method further comprises:
sending, by the communications apparatus to the network device, the PUCCH carrying the acknowledgement message, wherein the transmit power of the PUCCH is determined based on the power control adjustment factor indicated by the TPC command.
4 . The method according to claim 3 , wherein the TPC command is an index value of a power control factor, and a correspondence between an index value of each power control factor and the power control adjustment factor is as follows:
TPC command
δ PUCCH,b,f,c (in dB)
0
−1
1
0
2
1
3
3
wherein δ PUCCH,b,f,c is the power control adjustment factor.
5 . The method according to claim 3 , wherein the TPC command is an index value of a power control factor, and a correspondence between an index value of each power control factor and the power control adjustment factor is as follows:
TPC command
δ PUCCH,b,f,c (in dB)
0
−6
1
−4
2
−2
3
0
4
2
5
4
6
6
7
8
wherein δ PUCCH,b,f,c is the power control adjustment factor.
6 . The method according to claim 1 , wherein a random access time-frequency resource used for sending the preamble is a random access time-frequency resource shared by two-step random access and four-step random access.
7 . The method according to claim 1 , wherein the method further comprises:
sending the first DCI scrambled by a first random access radio network temporary identifier (RA-RNTI), wherein the first DCI is used to schedule the PDSCH carrying the response information, and a calculation formula used to calculate the first RA-RNTI has one more preset offset value than a calculation formula of a radio network temporary identifier (RNTI) corresponding to four-step random access.
8 . The method according to claim 1 , wherein the method further comprises:
listening to the first DCI by using a first RA-RNTI, wherein the first DCI is used to schedule the PDSCH carrying the response information, and a calculation formula used to calculate the first RA-RNTI has one more preset offset value than a calculation formula of an RNTI corresponding to four-step random access.
9 . The method according to claim 1 , wherein the type of the response that the PDSCH carries, indicated by the first indication information in the first DCI, comprises:
that the response information is for a four-step random access request or that the response information is for a two-step random access request.
10 . The method according to claim 1 , wherein the type of the response that the PDSCH carries, indicated by the first indication information in the first DCI, comprises:
that the response information is for a two-step random access request and includes the contention resolution identity.
11 . A communications apparatus, comprising:
a transmitter, configured to:
send a random access request, wherein the random access request comprises a preamble and uplink data; and
a receiver, configured to:
receive first downlink control information (DCI), wherein the first DCI comprises first indication information that indicates a type of response that a physical downlink shared channel (PDSCH) carries;
receive a message comprising response information for the random access request, wherein the response information is carried on the PDSCH, and
when the type of the response indicated by the first indication information in the DCI matches a type of the random access request, demodulating the PDSCH,
the response information is sent after the uplink data is successfully decoded by a network device,
the response information comprises a contention resolution identity and first information, and
the first information comprises information indicating a resource used to feed back an acknowledgement message and a transmit power control (TPC) command, wherein the information indicating the resource used to feed back the acknowledgement message is for determining a time-frequency resource of a physical uplink control channel (PUCCH) that carries the acknowledgement message, and the TPC command indicates a power control adjustment factor for determining transmit power of the PUCCH.
12 . The apparatus according to claim 11 , wherein the response information further comprises at least one of a cell radio network temporary identifier (C-RNTI) or a timing advance command.
13 . The apparatus according to claim 11 , wherein the transmitter is further configured to:
send the PUCCH carrying the acknowledgement message, wherein the transmit power of the PUCCH is determined based on the power control adjustment factor indicated by the TPC command.
14 . The apparatus according to claim 13 , wherein the TPC command is an index value of a power control factor, and a correspondence between an index value of each power control factor and the power control adjustment factor is as follows:
TPC command
δ PUCCH,b,f,c (in dB)
0
−1
1
0
2
1
3
3
wherein δ PUCCH,b,f,c is the power control adjustment factor.
15 . The apparatus according to claim 13 , wherein the TPC command is an index value of a power control factor, and a correspondence between an index value of each power control factor and the power control adjustment factor is as follows:
TPC command
δ PUCCH,b,f,c (in dB)
0
−6
1
−4
2
−2
3
0
4
2
5
4
6
6
7
8
wherein δ PUCCH,b,f,c is the power control adjustment factor.
16 . The apparatus according to claim 11 , wherein the type of the response that the PDSCH carries, indicated by the first indication information in the first DCI, comprises:
that the response information is for a four-step random access request or that the response information is for a two-step random access request.
17 . The apparatus according to claim 11 , wherein the type of the response that the PDSCH carries, indicated by the first indication information in the first DCI, comprises:
that the response information is for a two-step random access request and includes the contention resolution identity.
18 . A non-transitory computer-readable storage medium, storing a program, wherein when the program is read and executed by a communications apparatus, the communications apparatus is enabled to implement operations comprising:
sending a random access request to a network device, wherein the random access request comprises a preamble and uplink data;
receiving first downlink control information (DCI), wherein the first DCI comprises first indication information that indicates a type of response that a physical downlink shared channel (PDSCH) carries;
receiving a message comprising response information for the random access request, wherein the response information is carried on the PDSCH; and
when the type of the response indicated by the first indication information in the DCI matches a type of the random access request, demodulating the PDSCH, wherein:
the response information is sent after the uplink data is successfully decoded by the network device,
the response information comprises a contention resolution identity and first information, and
the first information comprises information indicating a resource used to feed back an acknowledgement message and a transmit power control (TPC) command, wherein the information indicating the resource used to feed back the acknowledgement message is for determining a time-frequency resource of a physical uplink control channel (PUCCH) that carries the acknowledgement message, and the TPC command indicates a power control adjustment factor for determining transmit power of the PUCCH.
19 . The non-transitory computer-readable storage medium according to claim 18 , wherein the response information further comprises at least one of a C-RNTI or a timing advance command.
20 . The non-transitory computer-readable storage medium according to claim 18 , wherein the type of the response that the PDSCH carries, indicated by the first indication information in the first DCI, comprises:
that the response information is for a four-step random access request or that the response information is for a two-step random access request.