Controlling random-access channel (RACH) retransmissions for wireless communication

• US 10,484,151 B2
• Filed: 02/09/2018
• Issued: 11/19/2019
• Est. Priority Date: 03/02/2017
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Islam, Muhammad Nazmul, Luo, Tao, Li, Junyi
• Primary Examiner(s): Cattungal, Ajay
• Application Number:
  US15/892,690
• Publication Number:
  US 20180254859A1
• Time in Patent Office: 648 Days
• CPC Class Codes: H04L 1/189 Transmission or retransmission of more than one copy of a message
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• 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

Abstract

Various aspects of the disclosure provide for methods of communication. One method, at a base station, involves determining a maximum number of consecutive MSG1 retransmissions that a user equipment (UE) is permitted to perform, and transmitting the maximum number of consecutive MSG1 retransmissions to the UE. Another method involves receiving a maximum number of consecutive MSG1 retransmissions to be performed, and transmitting consecutive MSG1 retransmission signals for the maximum number of times.

Claims

1. A method of communication at a base station, comprising:

determining a maximum number of consecutive MSG1 retransmissions that a user equipment (UE) is permitted to perform;

transmitting information indicating the maximum number of consecutive MSG1 retransmissions to the UE;

receiving, before a random access response (RAR) window, a consecutive MSG1 retransmission from the UE; and

repeating the receiving, after the RAR window, one or more subsequent consecutive MSG1 retransmissions from the UE until the maximum number of consecutive MSG1 retransmissions has been received, wherein each subsequent consecutive MSG1 retransmission is received after a corresponding RAR window.

2. The method of claim 1, further comprising:

receiving a first number of consecutive MSG1 retransmissions from the UE, wherein the first number is equal to the maximum number;

determining a random backoff period for a next MSG1 retransmission at the UE;

transmitting the random backoff period to the UE; and

receiving the next MSG1 retransmission in accordance with the random backoff period.

3. The method of claim 1, further comprising:

transmitting an indication as to whether the UE is permitted to transmit with different transmit beams during consecutive MSG1 retransmissions.

4. The method of claim 3, further comprising:

receiving a first number of consecutive MSG1 retransmissions from the UE; and

transmitting to the UE an indication of a highest quality transmit beam among possible transmit beams.

5. The method of claim 1, further comprising:

transmitting an indication to the UE to transmit with a same preamble and a same resource during consecutive MSG1 retransmissions.

6. The method of claim 1, further comprising:

combining signals of two or more consecutive MSG1 retransmissions to decode a random access channel (RACH) signal, wherein the combining the signals of the consecutive MSG1 retransmissions comprises non-coherently adding power of the signals of the consecutive MSG1 retransmissions.

7. A method of communication at a user equipment (UE), comprising:

receiving information indicating a maximum number of consecutive MSG1 retransmissions to be performed; and

transmitting consecutive MSG1 retransmission signals for the maximum number of times,

wherein the transmitting consecutive MSG1 retransmission signals comprises;

transmitting, before a random access response (RAR) window, a consecutive MSG1 retransmission, and

repeating the transmitting, after the RAR window, one or more subsequent consecutive MSG1 retransmissions until the maximum number of consecutive MSG1 retransmissions has been transmitted, wherein each subsequent consecutive MSG1 retransmission is transmitted after a corresponding RAR window.

8. The method of claim 7, further comprising:

receiving a random backoff period for a next MSG1 retransmission; and

transmitting a MSG1 retransmission signal in accordance with the random backoff period.

9. The method of claim 7, further comprising:

receiving an authorization to transmit with different transmit beams during consecutive MSG1 retransmissions; and

transmitting consecutive MSG1 retransmission signals with different transmit beams.

10. The method of claim 9, further comprising:

receiving an indication of a highest quality transmit beam among possible transmit beams; and

transmitting consecutive MSG1 retransmission signals with the highest quality transmit beam.

11. The method of claim 7, further comprising:

receiving an indication to transmit with a same preamble and a same resource during consecutive MSG1 retransmissions; and

transmitting consecutive MSG1 retransmission signals with a same preamble and a same resource.

12. An apparatus for communication, comprising:

a memory device; and

a processing circuit coupled to the memory device and configured to;

determine a maximum number of consecutive MSG1 retransmissions that a user equipment (UE) is permitted to perform,

transmit information indicating the maximum number of consecutive MSG1 retransmissions to the UE,

receive, before a random access response (RAR) window, a consecutive MSG1 retransmission from the UE, and

repeatedly receive, after the RAR window, one or more subsequent consecutive MSG1 retransmissions from the UE until the maximum number of consecutive MSG1 retransmissions has been received, wherein each subsequent consecutive MSG1 retransmission is received after a corresponding RAR window.

13. The apparatus of claim 12, wherein the processing circuit is further configured to:

receive a first number of consecutive MSG1 retransmissions from the UE, wherein the first number is equal to the maximum number;

determine a random backoff period for a next MSG1 retransmission at the UE;

transmit the random backoff period to the UE; and

receive the next MSG1 retransmission in accordance with the random backoff period.

14. The apparatus of claim 12, wherein the processing circuit is further configured to:

transmit an indication as to whether the UE is permitted to transmit with different transmit beams during consecutive MSG1 retransmissions.

15. The apparatus of claim 14, wherein the processing circuit is further configured to:

receive a first number of consecutive MSG1 retransmissions from the UE; and

transmit to the UE an indication of a highest quality transmit beam among possible transmit beams.

16. The apparatus of claim 12, wherein the processing circuit is further configured to:

transmit an indication to the UE to transmit with a same preamble and a same resource during consecutive MSG1 retransmissions.

17. The apparatus of claim 12, wherein the processing circuit is further configured to:

combine signals of two or more consecutive MSG1 retransmissions to decode a random access channel (RACH) signal; and

non-coherently add power of the signals of the consecutive MSG1 retransmissions to decode the RACH signal.

18. An apparatus for communication, comprising:

a memory device; and

a processing circuit coupled to the memory device and configured to;

receive information indicating a maximum number of consecutive MSG1 retransmissions to be performed,

transmit consecutive MSG1 retransmission signals for the maximum number of times, wherein the processing circuit configured to transmit is further configured to;

transmit, before a random access response (RAR) window, a consecutive MSG1 retransmission, and

repeatedly transmit, after the RAR window, one or more subsequent consecutive MSG1 retransmissions until the maximum number of consecutive MSG1 retransmissions has been transmitted, wherein each subsequent consecutive MSG1 retransmission is transmitted after a corresponding RAR window.

19. The apparatus of claim 18, wherein the processing circuit is further configured to:

receive a random backoff period for a next MSG1 retransmission; and

transmit a MSG1 retransmission signal in accordance with the random backoff period.

20. The apparatus of claim 18, wherein the processing circuit is further configured to:

receive an authorization to transmit with different transmit beams during consecutive MSG1 retransmissions; and

transmit consecutive MSG1 retransmission signals with different transmit beams.

21. The apparatus of claim 20, wherein the processing circuit is further configured to:

receive an indication of a highest quality transmit beam among possible transmit beams; and

transmit consecutive MSG1 retransmission signals with the highest quality transmit beam.

22. The apparatus of claim 18, wherein the processing circuit is further configured to:

receive an indication to transmit with a same preamble and a same resource during consecutive MSG1 retransmissions; and

transmit consecutive MSG1 retransmission signals with a same preamble and a same resource.