IP Library › Granted Patent US 12690068
Granted Patent B2
US 12690068 · App. 17/797,658 · Granted Jul 21, 2026

Random access in communication system

Inventors: Samuli Turtinen (Ii, FI); Chunli Wu (Beijing, CN)
Assignee: NOKIA TECHNOLOGIES OY
H04W74/0833H04W74/004H04W74/02H04W74/0836H04W74/0838
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Quick Facts
Patent No.
US 12690068
App. No.
17/797,658
Granted
Jul 21, 2026
Kind
B2
Abstract

Embodiments of the present disclosure relate to random access in a communication system. A first device determines whether a contention-free random access resource is allocated from a second device for a first random access type. In accordance with a determination that the contention-free random access resource is allocated, the first device compares a target transport block size corresponding to the contention-free random access resource with a first transport block size configured for a first group of preambles available for the first random access type, and performs random access to the second device based on a result of the comparison.

Claims (45)

1 . A user equipment comprising:

at least one processor; and

at least one memory comprising instructions stored thereon that, when executed by the at least one processor, cause the user equipment to perform at least:

selecting, for two-step contention-based random access, a preamble group of a plurality of preamble groups configured for the user equipment,

wherein, in a case that a resource for a two-step contention-free random access is configured for the user equipment, the preamble group is selected based on whether a first transport block size indicating a size of payload that can be transmitted using the resource for the two-step contention-free random access corresponds to a second transport block size configured for the preamble group being selected; and

transmitting a two-step contention-based random access message to a network device,

the two-step contention-based random access message comprising a preamble from the selected preamble group and a payload of the second transport block size.

2 . The user equipment according to claim 1 , wherein the instructions stored in the at least one memory, when executed by the at least one processor, further cause the user equipment to perform:

switching to four-step contention-based random access in a case that the two-step contention-based random access is not successfully completed after transmitting the two-step contention-based random access message.

3 . The user equipment according to claim 2 , wherein the instructions stored in the at least one memory, when executed by the at least one processor, further cause the user equipment to perform the switching to the four-step contention-based random access after performing a number of random access attempts.

4 . The user equipment according to claim 3 , wherein the number of random access attempts comprises a number of two-step contention-free random access attempts or a number of two-step contention-based random access attempts.

5 . The user equipment according to claim 2 , wherein the instructions, when executed by the at least one processor, cause the user equipment to perform a random access attempt, after switching to the four-step contention-based random access, based on said selection of the preamble group for the two-step contention-based random access.

6 . The user equipment according to claim 1 , wherein the plurality of preamble groups includes at least a preamble group A and a preamble group B, and wherein the instructions stored in the at least one memory, when executed by the at least one processor, further cause the user equipment to perform:

selecting the preamble group B if the first transport block size corresponds to the second transport block size.

7 . The user equipment according to claim 6 , wherein the instructions stored in the at least one memory, when executed by the at least one processor, further cause the user equipment to perform:

selecting the preamble group A if the first transport block size does not correspond to the second transport block size.

8 . A method performed by a user equipment, the method comprising:

selecting, for two-step contention-based random access, a preamble group of a plurality of preamble groups configured for the user equipment,

wherein, in a case that a resource for a two-step contention-free random access is configured for the user equipment, the preamble group is selected based on whether a first transport block size indicating a size of payload that can be transmitted using the resource for the two-step contention-free random access corresponds to a second transport block size configured for the preamble group being selected; and

transmitting a two-step contention-based random access message to a network device,

the two-step contention-based random access message comprising a preamble from the selected preamble group and a payload of the second transport block size.

9 . The method according to claim 8 , further comprising:

switching to four-step contention-based random access in a case that the two-step contention-based random access is not successfully completed after transmitting the two-step contention-based random access message.

10 . The method according to claim 9 , wherein the switching to the four-step contention-based random access is carried out after performing a number of random access attempts.

11 . The method according to claim 10 , wherein the number of random access attempts comprises a number of two-step contention-free random access attempts or a number of two-step contention-based random access attempts.

12 . The method according to claim 9 , further comprising:

performing a random access attempt, after switching to the four-step contention-based random access, based on said selection of the preamble group for the two-step contention-based random access.

13 . The method according to claim 8 , wherein the plurality of preamble groups includes at least a preamble group A and a preamble group B, and wherein the method further comprises:

selecting the preamble group B if the first transport block size corresponds to the second transport block size.

14 . The method according to claim 13 , further comprising:

selecting the preamble group A if the first transport block size does not correspond to the second transport block size.

15 . A non-transitory computer-readable storage medium comprising instruction stored therein that, when executed by at least one processor of a user equipment, cause the user equipment to perform at least:

selecting, for two-step contention-based random access, a preamble group of a plurality of preamble groups configured for the user equipment,

wherein, in a case that a resource for a two-step contention-free random access is configured for the user equipment, the preamble group is selected based on whether a first transport block size indicating a size of payload that can be transmitted using the resource for the two-step contention-free random access corresponds to a second transport block size configured for the preamble group being selected; and

transmitting a two-step contention-based random access message to a network device,

the two-step contention-based random access message comprising a preamble from the selected preamble group and a payload of the second transport block size.

16 . The non-transitory computer-readable storage medium according to claim 15 , wherein the instructions stored therein are further configured, when executed by the at least one processor of the user equipment, further cause the user equipment to perform:

switching to four-step contention-based random access in a case that the two-step contention-based random access is not successfully completed after transmitting the two-step contention-based random access message.

17 . The non-transitory computer-readable storage medium according to claim 16 , wherein the switching to the four-step contention-based random access is carried out after performing a number of random access attempts.

18 . The non-transitory computer-readable storage medium according to claim 17 , wherein the number of random access attempts comprises a number of two-step contention-free random access attempts or a number of two-step contention-based random access attempts.

19 . The non-transitory computer-readable storage medium according to claim 17 , wherein the instructions stored therein are further configured, when executed by the at least one processor of the user equipment, further cause the user equipment to perform:

performing a random access attempt, after switching to the four-step contention-based random access, based on said selection of the preamble group for the two-step contention-based random access.

20 . The non-transitory computer-readable storage medium according to claim 15 , wherein the plurality of preamble groups includes at least a preamble group A and a preamble group B, and wherein the instructions stored therein are further configured, when executed by the at least one processor of the user equipment, further cause the user equipment to perform:

selecting the preamble group B if the first transport block size corresponds to the second transport block size; or

selecting the preamble group A if the first transport block size does not correspond to the second transport block size.