Retransmission of MsgB in two-step random access procedure

Patent metadata

Field	Value
Publication number	US-12010730-B2
Application number	US-202318334933-A
Country	US
Kind code	B2
Filing date	Jun 14, 2023
Priority date	Sep 29, 2019
Publication date	Jun 11, 2024
Grant date	Jun 11, 2024

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 a physical downlink control channel (PDCCH);
monitoring the PDCCH for one or more transmissions of a downlink message, wherein the one or more transmissions of the downlink message are part of a two-step random access procedure;
decoding downlink control information (DCI) in a first of the one or more transmissions of the downlink message within the window using a message B (MSGB) Radio Network Temporary Identity (RNTI), wherein the MSGB-RNTI is based on location parameters of a physical uplink resource that was used by a user equipment (UE) to transmit a random access preamble of the two-step random access procedure; and
determining, based on a field in the decoded DCI indicating a time sub-window number, that the decoded DCI is intended for the UE.

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

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 3 , wherein the window for monitoring the PDCCH 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 the UE device in order to determine whether the first of the one or more transmissions includes random access response (RAR) information targeted for the UE device.

6. The method of claim 1 , wherein the time duration is sufficiently large to include up to N transmissions of the downlink 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 downlink message includes at least one grant of transmission resources and at least one contention resolution identity.

9. An apparatus, comprising:
at least one processor configured to 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 a physical downlink control channel (PDCCH); and
monitor the PDCCH for one or more transmissions of a downlink message, wherein the one or more transmissions of the downlink message are part of a two-step random access procedure;
decode downlink control information, DCI, in a first of the one or more transmissions of the downlink message within the window using a message B (MSGB) Radio Network Temporary Identity (RNTI), wherein the MSGB-RNTI is based on location parameters of a physical uplink resource that was used by the UE to transmit a random access preamble of the two-step random access procedure; and
determine, based on a field in the decoded DCI that resolves DCI transmissions relating to random access preamble transmissions in different radio frames using a same MSB-RNTI, whether to accept or reject the decoded DCI.

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

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

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

13. The apparatus of claim 9 , wherein the window for monitoring the PDCCH is larger than a sub-window.

14. The apparatus of claim 9 , wherein, as part of the monitoring of the PDCCH, the at least one processor is further configured to cause the UE to:
recover a transmission number from the first of the one or more transmissions; and
compare the transmission number with a current window number of the UE device in order to determine whether the first of the one or more transmissions includes random access response (RAR) information targeted for the UE device.

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

16. The apparatus of claim 9 , further comprising:
a radio operably coupled to the at least one processor.

17. A non-transitory computer readable storage medium storing program instructions executable by one or more processors to 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 a physical downlink control channel (PDCCH);
monitor the PDCCH for one or more transmissions of a downlink message, wherein the one or more transmissions of the downlink message are part of a two-step random access procedure;
decode downlink control information (DCI) in a first of the one or more transmissions of the downlink message within the window using a message B (MSGB) Radio Network Temporary Identity (RNTI), wherein the MSGB-RNTI is based on location parameters of a physical uplink resource that was used by a user equipment (UE) to transmit a random access preamble of the two-step random access procedure; and
determine, based on a field in the decoded DCI indicating a time sub-window number, that the decoded DCI is intended for the UE.

18. The non-transitory computer readable storage medium of claim 17 , wherein the time sub-window number is associated with a time of the random access preamble transmission.

19. The non-transitory computer readable storage medium of claim 17 , 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 non-transitory computer readable storage medium of claim 17 , wherein the window for monitoring the PDCCH is larger than a sub-window.

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

• H04W72/1268 Primary

  of uplink data flows · CPC title

• H04W74/0836

  with 2-step access · CPC title

• H04W74/0833 Primary

  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