BEAM INDICATION DURING RANDOM ACCESS CHANNEL (RACH) PROCEDURE

• US 20190029049A1
• Filed: 07/17/2018
• Published: 01/24/2019
• Est. Priority Date: 07/18/2017
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: AKKARAKARAN, Sony, JOHN WILSON, Makesh Pravin, LUO, Tao, NAGARAJA, Sumeeth
• Granted Patent: US 10,805,959 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time
• CPC Class Codes: H04W 72/046 the resource being in the space domain, e.g. beams
• CPC Class Codes: H04W 72/542 using measured or perceived quality
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

Certain aspects of the present disclosure provide techniques for random-access channel (RACH) communication. For example, certain aspects provide a method for providing an indication, via a first uplink transmission, of a preferred beam for a subsequent (uplink or downlink) transmission.

Claims

1. A method for wireless communications by a user equipment (UE), comprising:

determining at least one preferred beam for at least one subsequent transmission, based on one or more downlink signals and an anticipated time of the at least one subsequent transmission; and

providing an indication of the preferred beam via a first uplink transmission.

2. The method of claim 1, wherein:

the downlink signals are sent via a sweep across multiple beams; and

the preferred beam is determined based on receive signal quality of the multiple beams.

3. The method of claim 1, wherein the first uplink transmission is sent as part of a random access channel (RACH) procedure.

4. The method of claim 3, wherein:

the first uplink transmission comprises a transmission or retransmission of a first message sent during the RACH procedure; and

the preferred beam is determined, at least in part, on a duration of a random access response (RAR) window.

5. The method of claim 4, wherein a plurality of different beams are indicated for use at different times within the RAR window.

6. The method of claim 3, wherein:

the first uplink transmission comprises a RACH preamble transmission; and

at least two preferred beams are indicated for at least two transmissions that are part of the RACH procedure.

7. The method of claim 3, wherein an indication of at least one preferred beam for use after completion of the RACH procedure is provided.

8. The method of claim 3, wherein the indication is provided as payload of the first uplink transmission.

9. The method of claim 3, wherein:

the at least one subsequent transmission comprises a downlink transmission of the RACH procedure; and

the method further comprising processing the downlink transmission of the RACH procedure using a receive beam corresponding to the indicated preferred beam.

10. The method of claim 1, further comprising:

receiving configuration information indicating a partitioning of different sets of resources to use for indicating different preferred beams; and

the indication of the preferred beam is provided based on resources selected for the first uplink transmission based on the partitioning.

11. The method of claim 10, wherein:

a first combination of preferred beams is indicated by selecting resources from a first set of the different sets of resources for the first uplink transmission;

or

a second combination of preferred beams is indicated by selecting resources from a second set of the different sets of resources for the first uplink transmission.

12. The method of claim 10, wherein:

using resources from a first set of resources for the first uplink transmission indicates the preferred beam has a first beam index offset relative to a beam index used for the first uplink transmission; and

using resources from a second set of resources for the first uplink transmission indicates the preferred beam has a second beam index offset relative to the beam index used for the first uplink transmission.

13. The method of claim 10, wherein the configuration information is received via at least one of a master information block (MIB) or remaining minimum system information (RMSI).

14. The method of claim 10, wherein:

each set of resources comprise a combination of at least one sequence index, time location, and frequency location.

15. A method for wireless communications by a network entity, comprising:

signaling configuration information indicating a partitioning of different sets of resources to use for indicating different preferred beams;

receiving a first uplink transmission from a user equipment (UE) sent using one of the sets of resources; and

determining, based on the partitioning and the set of resources used to send the first uplink transmission, at least one preferred beam for at least one subsequent transmission.

16. The method of claim 15, wherein the determining comprises:

determining a first combination of preferred beams for at least two subsequent transmissions is indicated if the first uplink transmission is received using a first one of the sets of resources;

or

determining a second combination of preferred beams for the at least two subsequent transmissions is indicated if the first uplink transmission is received using a second one of the sets of resources.

17. The method of claim 15, wherein the first uplink transmission is sent as part of a random access channel (RACH) procedure.

18. The method of claim 17, wherein:

the first uplink transmission comprises a transmission or retransmission of a first message sent during the RACH procedure; and

a plurality of different beams are indicated for use at different times within a random access response (RAR) window.

19. The method of claim 17, wherein:

the first uplink transmission comprises a RACH preamble transmission; and

at least two preferred beams are indicated for at least two transmissions that are part of the RACH procedure.

20. The method of claim 17, wherein an indication of at least one preferred beam for use after completion of the RACH procedure is provided.

21. The method of claim 17, wherein the indication is provided as payload of the first uplink transmission.

22. The method of claim 17, wherein:

the at least one subsequent transmission comprises a downlink transmission of the RACH procedure; and

the method further comprising processing the downlink transmission of the RACH procedure using a receive beam corresponding to the indicated preferred beam.

23. The method of claim 15, wherein:

a first set of resources for the first uplink transmission indicates the preferred beam has a first beam index offset relative to a beam index used for the first uplink transmission; and

a second set of resources for the first uplink transmission indicates the preferred beam has a second beam index offset relative to the beam index used for the first uplink transmission.

24. The method of claim 15, wherein the configuration information is signaled via at least one of a master information block (MIB) or remaining minimum system information (RMSI).

25. The method of claim 15, wherein:

each set of resources comprise a combination of at least one sequence index, time location, and frequency location.

26. An apparatus for wireless communications by a user equipment (UE), comprising:

means for determining at least one preferred beam for at least one subsequent transmission, based on one or more downlink signals and an anticipated time of the at least one subsequent transmission; and

means for providing an indication of the preferred beam via a first uplink transmission.

27. An apparatus for wireless communications by a network entity, comprising:

means for signaling configuration information indicating a partitioning of different sets of resources to use for indicating different preferred beams;

means for receiving a first uplink transmission from a user equipment (UE) sent using one of the sets of resources; and

means for determining, based on the partitioning and the set of resources used to send the first uplink transmission, at least one preferred beam for at least one subsequent transmission.