Random access method and apparatus, network device, and terminal

1. A method for random access, comprising:

sending, by a network device, first configuration information corresponding to a preamble and second configuration information corresponding to a physical random access channel (PRACH) resource;

receiving, by the network device, MSG1, and determining a format of random access response (RAR) based on at least one of a preamble corresponding to the MSG1, a PRACH resource corresponding to the MSG1, or whether MSG3 is detected within a first time range; and

sending, by the network device, MSG2, based on the format of RAR,

wherein the first configuration information comprises a first set of preambles for a two-step random access procedure and a second set of preambles for a four-step random access procedure,

wherein the receiving, by the network device, the MSG1, and the determining the format of RAR based on the preamble corresponding to the MSG1 comprises:

receiving, by the network device, a first preamble and a second preamble on a same PRACH resource, wherein the first preamble belongs to the first set of preambles for the two-step random access procedure, and the second preamble belongs to the second set of preambles for the four-step random access procedure; and

determining, by the network device, that the first preamble corresponds to a first RAR format, and determining, by the network device, that the second preamble corresponds to a second RAR format, wherein the first RAR format is used for the two-step random access procedure, and the second RAR format is used for the four-step random access procedure.

2. The method according to claim 1 , wherein the second configuration information comprises a first PRACH resource for the two-step random access procedure and the four-step random access procedure.

3. The method according to claim 1 , further comprising:

sending, by the network device, third configuration information corresponding to a physical uplink shared channel (PUSCH) resource, wherein the PUSCH resource is used for transmission of the MSG3 in the two-step random access procedure.

4. A network device, comprising:

a processor; and

a memory,

wherein the memory is used to store a computer program, and the processor is configured to call and run the computer program stored in the memory to:

send first configuration information corresponding to a preamble and second configuration information corresponding to a PRACH resource;

receive MSG1;

determine a format of RAR, based on at least one of a preamble corresponding to the MSG1, a PRACH resource corresponding to the MSG1, or whether MSG3 is detected within a first time range; and

send MSG2, based on the format of RAR;

wherein the first configuration information comprises a first set of preambles for a two-step random access procedure and a second set of preambles for a four-step random access procedure,

wherein, the processor is further configured to:

receive a first preamble and a second preamble on a same PRACH resource, wherein the first preamble belongs to the first set of preambles for the two-step random access procedure, and the second preamble belongs to the second set of preambles for the four-step random access procedure; and

determine that the first preamble corresponds to a first RAR format, and the second preamble corresponds to a second RAR format, wherein the first RAR format is used for the two-step random access procedure, and the second RAR format is used for the four-step random access procedure.

5. The network device according to claim 4 , wherein the second configuration information comprises a first PRACH resource for the two-step random access procedure and the four-step random access procedure.

6. The network device according to claim 4 , wherein the processor is further configured to send third configuration information corresponding to a PUSCH resource, and the PUSCH resource is used for transmission of the MSG3 in the two-step random access procedure.

7. A terminal, comprising:

a processor; and

a memory,

wherein the memory is used to store a computer program, and the processor is configured to call and run the computer program stored in the memory to:

obtain first configuration information corresponding to a preamble and second configuration information corresponding to a PRACH resource, wherein the first configuration information comprises a first set of preambles for a two-step random access procedure and a second set of preambles for a four-step random access procedure, and the second configuration information comprises a first PRACH resource for the two-step random access procedure and the four-step random access procedure;

when the two-step random access procedure is initiated, select a first preamble from the first set of preambles, and select the first PRACH resource for sending MSG1;

when the four-step random access procedure is initiated, select a second preamble from the second set of preambles, and select the first PRACH resource for sending MSG1; and

send the MSG1 so that the network device determines that the first preamble corresponds to a first RAR format and that the second preamble corresponds to a second RAR format, wherein the first RAR format is used for the two-step random access procedure, and the second RAR format is used for the four-step random access procedure.

8. The terminal according to claim 7 , wherein the processor is further configured to obtain third configuration information corresponding to a PUSCH resource, wherein the PUSCH resource is used for transmission of MSG3 in the two-step random access procedure.

9. The terminal according to claim 7 , wherein the processor is further configured to:

receive MSG2, wherein a RAR MAC PDU in the MSG2 carries first indication information, and the first indication information is used to indicate whether the RAR MAC PDU carries a first RAR or a second RAR; and

decode based on the first indication information to obtain the first RAR or the second RAR.

10. A method for random access, comprising:

obtaining, by a terminal, first configuration information corresponding to a preamble and second configuration information corresponding to a PRACH resource, wherein the first configuration information comprises a first set of preambles used for a two-step random access procedure and a second set of preambles used for a four-step random access procedure, and the second configuration information comprises a first PRACH resource used for the two-step random access procedure and the four-step random access procedure;

when the terminal initiates the two-step random access procedure, selecting a first preamble from the first set of preambles and selecting the first PRACH resource by the terminal for sending MSG1; and when the terminal initiates the four-step random access procedure, selecting a second preamble from the second set of preambles and selecting the first PRACH resource by the terminal for sending MSG1, so that the network device determines that the first preamble corresponds to a first RAR format and that the second preamble corresponds to a second RAR format, wherein the first RAR format is used for the two-step random access procedure, and the second RAR format is used for the four-step random access procedure.

11. The method according to claim 10 , further comprising:

receiving, by the terminal, MSG2, wherein RAR MAC PDU in the MSG2 carries first indication information, and the first indication information is used to indicate whether the RAR MAC PDU carries a first RAR or a second RAR; and

decoding, by the terminal, based on the first indication information to obtain the first RAR or the second RAR.

12. The method according to claim 10 , further comprising:

obtaining, by the terminal, third configuration information corresponding to a PUSCH resource, wherein the PUSCH resource is used for transmission of MSG3 in the two-step random access procedure.