Retransmission of MsgB in two-step random access procedure

Patent metadata

Field	Value
Publication number	US-12490260-B2
Application number	US-202418652003-A
Country	US
Kind code	B2
Filing date	May 1, 2024
Priority date	Sep 29, 2019
Publication date	Dec 2, 2025
Grant date	Dec 2, 2025

Abstract

A wireless user equipment (UE) device may transmit a random access preamble to a base station, using a physical resource on an uplink signal. After failing to receive an initial transmission of a response message from the base station (BS), the UE device may monitor for one or more retransmissions of the response message. Each of the retransmission may include a corresponding transmission number. As an alternative, each of the retransmissions may be at least partially scrambled using a corresponding Radio Network Temporary Identifier (RNTI). As another alternative, a window for monitoring and RNTI calculation may be extended to include the one or more retransmissions. The successive retransmissions may include the same set of UE-specific payloads, or, a decreasing set of payloads over time as UE devices acknowledge successful receipt of their respective payloads.

First claim

We claim:

1 . A method, comprising:
receiving a configuration message from a base station, wherein the configuration message indicates a time duration of a window for monitoring for a random access response (RAR) message; monitoring for one or more transmissions of the RAR message, wherein the one or more transmissions of the RAR message are part of a two-step random access procedure; receiving downlink control information (DCI) in a first of the one or more transmissions of the RAR message within the window using a message B (MSGB) Radio Network Temporary Identity (RNTI), wherein the MSGB-RNTI is associated with location parameters of a physical uplink resource that was used to transmit a random access preamble of the two-step random access procedure; and determining, based at least in part on a field in the DCI indicating a time sub-window number, that the DCI is intended for a user equipment (UE) that transmitted the random access preamble and to decode the one or more transmissions.

2 . The method of claim 1 , wherein the time sub-window number is associated with a time of transmission of the random access preamble.

3 . The method of claim 1 , wherein the time sub-window number resolves DCI transmissions relating to random access preamble transmissions in different radio frames using a same MSGB-RNTI.

4 . The method of claim 1 , wherein the window for monitoring for the RAR message is larger than a sub-window.

5 . The method of claim 1 , wherein said monitoring includes:
recovering a transmission number from the first of the one or more transmissions; and comparing the transmission number with a current window number of a user equipment (UE) in order to determine whether the first of the one or more transmissions includes RAR information targeted for the UE.

6 . The method of claim 1 , wherein the time duration is sufficiently large to include up to N transmissions of the RAR message, and wherein N is greater than one.

7 . The method of claim 1 , further comprising:
transmitting, in response to successfully receiving the first of the one or more transmissions, an acknowledge message.

8 . The method of claim 1 , wherein the RAR message includes at least one grant of transmission resources and at least one contention resolution identity.

9 . An apparatus, comprising:
a processor configured to, when executing instructions stored in a memory, perform operations comprising:
receiving a configuration message from a base station, wherein the configuration message indicates a time duration of a window for monitoring for a random access response (RAR) message;
monitoring for one or more transmissions of the RAR message, wherein the one or more transmissions of the RAR message are part of a two-step random access procedure;
receiving downlink control information (DCI) in a first of the one or more transmissions of the RAR message within the window using a message B (MSGB) Radio Network Temporary Identity (RNTI), wherein the MSGB-RNTI is associated with location parameters of a physical uplink resource that was used to transmit a random access preamble of the two-step random access procedure; and
determining, based at least in part on a field in the DCI indicating a sub-window number, that the DCI is intended for the UE that transmitted the random access preamble and to decode the one or more transmissions.

10 . The apparatus of claim 9 , wherein the time sub-window number resolves DCI transmissions relating to random access preamble transmissions in different radio frames using a same MSGB-RNTI.

11 . The apparatus of claim 10 , wherein the time sub-window number is associated with a time of transmission of the random access preamble.

12 . The apparatus of claim 9 , wherein the time sub-window number is associated with a time of the random access preamble transmission.

13 . The apparatus of claim 9 , wherein, as part of the monitoring, the operations further comprise:
recovering a transmission number from the first of the one or more transmissions; and comparing the transmission number with a current window number of the UE in order to determine whether the first of the one or more transmissions includes RAR information targeted for the UE.

14 . The apparatus of claim 9 , wherein the RAR message includes at least one grant of transmission resources and at least one contention resolution identity.

15 . The apparatus of claim 9 , further comprising:
a radio operably coupled to the processor.

16 . A baseband processor, comprising:
memory storing instructions that, when executed, cause a user equipment (UE) to:
receive a configuration message from a base station, wherein the configuration message indicates a time duration of a window for monitoring for a random access response (RAR) message;
monitor for one or more transmissions of the RAR message, wherein the one or more transmissions of the RAR message are part of a two-step random access procedure;
receive downlink control information (DCI) in a first of the one or more transmissions of the RAR message within the window using a message B (MSGB) Radio Network Temporary Identity (RNTI), wherein the MSGB-RNTI is associated with location parameters of a physical uplink resource that was used to transmit a random access preamble of the two-step random access procedure; and
determine, based at least in part on a field in the DCI indicating a time sub-window number, that the DCI is intended for the UE that transmitted the random access preamble and to process a second of the one or more transmissions.

17 . The baseband processor of claim 16 , wherein the time sub-window number is associated with a time of transmission of the random access preamble.

18 . The baseband processor of claim 16 , wherein the window for monitoring for the RAR message is larger than a sub-window.

19 . The baseband processor of claim 16 , wherein the time sub-window number resolves DCI transmissions relating to random access preamble transmissions in different radio frames using a same MSGB-RNTI.

20 . The baseband processor of claim 16 , wherein the time duration is sufficiently large to include up to N transmissions of the RAR message, and wherein N is greater than one.

Assignees

• Apple Inc

Inventors

• Yao Chunhai
• Rodgers Clive E
• Zhang Dawei
• Xu Fangli
• Hu Haijing
• Sun Haitong
• Zeng Wei
• Chen Yuqin
• Zhang Yushu
• Wu Zhibin

Classifications

• H04W74/0836

  with 2-step access · CPC title

• H04W74/0833

  Random access procedures, e.g. with 4-step access · CPC title

• H04W74/006 Primary

  in the downlink, i.e. towards the terminal · CPC title

• H04W72/232

  the control data signalling from the physical layer, e.g. DCI signalling · CPC title

• H04W72/0446

  Resources in time domain, e.g. slots or frames · CPC title