Random access method and apparatus, device, and storage medium
A random access method includes sending a random access preamble to a base station on a first time domain resource, obtaining an index value of the first time domain resource, obtaining an index difference between the first time domain resource and a second time domain resource, obtaining an index value of the second time domain resource by adding the index value of the first time domain resource and the index difference, obtaining a random access radio network temporary identifier (RA-RNTI) based on the index value of the second time domain resource, receiving a random access response (RAR) from the base station, and descrambling a cyclic redundancy check (CRC) code of the RAR using the RA-RNTI.
1. A method, comprising:
receiving, from a base station, broadcast information, wherein the broadcast information is used for determining an index of a first time domain resource;
sending, to the base station, on a second time domain resource, a random-access preamble, wherein the second time domain resource is determined based on the index of the first time domain resource and an offset, wherein the offset is used for obtaining an index difference between the first time domain resource and the second time domain resource, and wherein the offset is carried in a system information block (SIB) from the base station;
obtaining a random access radio network temporary identifier (RA-RNTI) based on the index of the second time domain resource;
receiving, from the base station, a random-access response (RAR); and
descrambling a cyclic redundancy check (CRC) code of the RAR by using the RA-RNTI.
2. The method of claim 1 , wherein the offset is based on a rounding operation on a quotient of dividing a minimum round trip delay (RTD) by a duration, wherein the minimum RTD is based on a shortest distance between the base station and a target cell, and wherein the target cell serves a communication apparatus.
3. The method of claim 2 , wherein the RAR comprises a processed timing advance (TA), wherein the method further comprises calculating, based on the processed TA using a formula, an unprocessed TA when the CRC code of the RAR is successfully descrambled, wherein the formula comprises: TA=TA new +p, wherein TA is the unprocessed TA, wherein TA new is the processed TA, and wherein p is the offset.
4. The method of claim 1 , wherein the RAR comprises a processed timing advance (TA), wherein the method further comprises calculating, based on the processed TA using a formula, an unprocessed TA when the CRC code of the RAR is successfully descrambled, wherein the formula comprises: TA=TA new +RTD rough , wherein TA is the unprocessed TA, wherein TA new is the processed TA, and wherein RTD rough is a rough round trip delay (RTD).
5. The method of claim 1 , wherein the first time domain resource is a first slot of a first physical random-access channel (PRACH).
6. An apparatus, comprising:
a non-transitory memory configured to store instructions; and
one or more processors coupled to the non-transitory memory, wherein the instructions cause the one or more processors to:
receive, from a base station, broadcast information, wherein the broadcast information is used for determining an index of a first time domain resource;
send, to the base station, on a second time domain resource, a random-access preamble, wherein the second time domain resource is determined based on the index of the first time domain resource and an offset, wherein the offset is used for obtaining an index difference between the first time domain resource and the second time domain resource, and wherein the offset is carried in a system information block (SIB) from the base station;
obtain a random access radio network temporary identifier (RA-RNTI) based on the index of the second time domain resource;
receive, from the base station, a random-access response (RAR); and
descramble a cyclic redundancy check (CRC) code of the RAR by using the RA-RNTI.
7. The apparatus of claim 6 , wherein the offset is based on a rounding operation on a quotient of dividing a minimum round trip delay (RTD) by a duration, wherein the minimum RTD is based on a shortest distance between the base station and a target cell, and wherein the target cell serves the apparatus.
8. The apparatus of claim 7 , wherein the RAR comprises a processed timing advance (TA), wherein the one or more processors are further configured to execute the instructions to calculate, based on the processed TA using a formula, an unprocessed TA when the CRC code of the RAR is successfully descrambled, wherein the formula comprises: TA=TA new +p, wherein TA is the unprocessed TA, wherein TA new is the processed TA, and wherein p is the offset.
9. The apparatus of claim 7 , wherein the RAR comprises a processed timing advance (TA), wherein the one or more processors are further configured to execute the instructions to calculate, based on the processed TA using a formula, an unprocessed TA when the CRC of the RAR is successfully descrambled, wherein the formula comprises: TA=TA new +p+1, wherein TA is the unprocessed TA, wherein TA new is the processed TA, and wherein p is the offset.
10. The apparatus of claim 6 , wherein the RAR comprises a processed timing advance (TA), wherein the one or more processors are further configured to execute the instructions to calculate, based on the processed TA using a formula, an unprocessed TA when the CRC code of the RAR is successfully descrambled, wherein the formula comprises: TA=TA new +RTD rough , wherein TA is the unprocessed TA, wherein TA new is the processed TA, and wherein RTD rough is a rough round trip delay (RTD).
11. The apparatus of claim 6 , wherein the first time domain resource is a first slot of a first physical random-access channel (PRACH).
12. A computer program product comprising instructions that are stored on a non-transitory computer-readable storage medium and that, when executed by one or more processors, cause an apparatus to:
receive, from a base station, broadcast information, wherein the broadcast information is used for determining an index of a first time domain resource;
send, to the base station, on a second time domain resource, a random-access preamble, wherein the second time domain resource is determined based on the index of the first time domain resource and an offset, wherein the offset is used for obtaining an index difference between the first time domain resource and the second time domain resource, and wherein the offset is carried in a system information block (SIB) from the base station;
obtain a random access radio network temporary identifier (RA-RNTI) based on the index of the second time domain resource;
receive, from the base station, a random-access response (RAR); and
descramble a cyclic redundancy check (CRC) code of the RAR by using the RA-RNTI.
13. The computer program product of claim 12 , wherein the offset is based on a rounding operation on a quotient of dividing a minimum round trip delay (RTD) by a duration, wherein the minimum RTD is based on a shortest distance between the base station and a target cell, and wherein the target cell serves a communication apparatus.
14. The computer program product of claim 13 , wherein the RAR comprises a processed timing advance (TA), wherein the one or more processors are further configured to execute the instructions to cause the apparatus to calculate, based on the processed TA using a formula, an unprocessed TA when the CRC code of the RAR is successfully descrambled, wherein the formula comprises: TA=TA new +p, wherein TA is the unprocessed TA, wherein TA new is the processed TA, and wherein p is the offset.
15. The computer program product of claim 12 , wherein the RAR comprises a processed timing advance (TA), wherein the one or more processors are further configured to execute the instructions to cause the apparatus to calculate, based on the processed TA using a formula, an unprocessed TA when the CRC code of the RAR is successfully descrambled, wherein the formula comprises: TA=TA new +RTD rough , wherein TA is the unprocessed TA, wherein TA new is the processed TA, and wherein RTD rough is a rough round trip delay (RTD).
16. The computer program product of claim 12 , wherein the first time domain resource is a first slot of a first physical random-access channel (PRACH).