HANDLING OF DISRUPTED SYNCHRONOUS HYBRID AUTOMATIC REPEAT REQUEST (HARQ) CYCLE AT SYSTEM TIME ROLLOVER

• US 20100050039A1
• Filed: 08/20/2009
• Published: 02/25/2010
• Est. Priority Date: 08/21/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Xu, Hao, Zhang, Xiaoxia, Meylan, Arnaud, Liu, Zhengwei
• Granted Patent: US 8,473,799 B2
• Time in Patent Office: Days
• US Class Current: 714/749
• CPC Class Codes: H04L 1/1803 Stop-and-wait protocols
• CPC Class Codes: H04L 1/1822 involving configuration of automatic repeat request [ARQ] with parallel processes
• CPC Class Codes: H04L 1/1874 Buffer management

Abstract

Certain aspects of the present disclosure propose techniques for avoiding a disruption in synchronous hybrid automatic repeat request operation at system time rollover. The techniques define the behavior of a system before and after the system frame number (SFN) rollover point to ensure a known relationship between a hybrid automatic repeat request (HARQ) process identification number and system time.

Claims

1. A method for wireless communications, comprising:

identifying a system frame number (SFN) rollover time, indicating when a system frame number rolls over from a first value to a second value, wherein the second value is smaller than the first value;

stopping hybrid automatic repeat request (HARQ) operation at or near SFN rollover time for one or more HARQs; and

restarting uplink HARQ operation from the SFN rollover time.

2. The method of claim 1, further comprising:

adjusting the SFN rollover time for one or more user equipments in the system such that the rate of HARQ reset due to SFN rollover is constant in time.

3. The method of claim 1, further comprising:

determining a system rollover number M;

wherein the system rollover number is a difference between two consecutive SFN rollover times.

4. The method of claim 3, wherein the system rollover number M is a multiple of the least common multiple of one or more of the HARQ repetition periods of the uplink HARQ operations of the system, wherein the uplink HARQ operations of the system include a frequency division multiplexing mode, and a plurality of uplink-downlink configurations of a time division multiplexing mode.

5. The method of claim 1, wherein the system rollover number M is the largest integer that satisfies a relation

$n=\lceil$

log 2 

M 10 ⌉

,

wherein n is the number of bits defined in the SFN, log₂ is the logarithm in base two, and the function ┌

.┐

outputs the largest integer inside.

6. The method of claim 1, wherein stopping hybrid automatic repeat request (HARQ) operation at SFN rollover time for one or more HARQs comprises:

sending uplink grant message if the roundtrip processing of a message can be finished before SFN rollover time, wherein roundtrip processing of a message comprises transmitting the message and receiving a response to the message.

7. The method of claim 1, wherein stopping hybrid automatic repeat request (HARQ) operation at SFN rollover time for one or more HARQs comprises:

sending an uplink grant if the uplink transmission time ends before SFN rollover time.

8. The method of claim 7, further comprising:

combining HARQ processes that did not have time to send ACK/NACK before SFN rollover; and

sending the combined HARQ process using a process identification (ID) after SFN rollover time;

wherein the process ID is similar to a process ID before the SFN rollover time.

9. An apparatus for wireless communications, comprising:

logic for identifying a system frame number (SFN) rollover time, indicating when a system frame number rolls over from a first value to a second value, wherein the second value is smaller than the first value;

logic for stopping hybrid automatic repeat request (HARQ) operation at or near SFN rollover time for one or more HARQs; and

logic for restarting uplink HARQ operation from the SFN rollover time.

10. The apparatus of claim 9, further comprising:

logic for adjusting the SFN rollover time for one or more user equipments in the system such that the rate of HARQ reset due to SFN rollover is constant in time.

11. The apparatus of claim 9, further comprising:

logic for determining a system rollover number M;

wherein the system rollover number is a difference between two consecutive SFN rollover times.

12. The apparatus of claim 11, wherein the system rollover number M is a multiple of the least common multiple of one or more of the HARQ repetition periods of the uplink HARQ operations of the system, wherein the uplink HARQ operations of the system include a frequency division multiplexing mode, and a plurality of uplink-downlink configurations of a time division multiplexing mode.

13. The apparatus of claim 9, wherein the system rollover number M is the largest integer that satisfies a relation

$n=\lceil$

log 2 

M 10 ⌉

,

wherein n is the number of bits defined in the SFN, log₂ is the logarithm in base two, and the function ┌

.┐

outputs the largest integer inside.

14. The apparatus of claim 9, wherein the logic for stopping hybrid automatic repeat request (HARQ) operation at SFN rollover time for one or more HARQs comprises:

logic for sending uplink grant message if the roundtrip processing of a message can be finished before SFN rollover time, wherein roundtrip processing of a message comprises transmitting the message and receiving a response to the message.

15. The apparatus of claim 9, wherein the logic for stopping hybrid automatic repeat request (HARQ) operation at SFN rollover time for one or more HARQs comprises:

logic for sending an uplink grant if the uplink transmission time ends before SFN rollover time.

16. The apparatus of claim 15, further comprising:

logic for combining HARQ processes that did not have time to send ACK/NACK before SFN rollover; and

logic for sending the combined HARQ process using a process identification (ID) after SFN rollover time;

wherein the process ID is similar to a process ID before the SFN rollover time.

17. An apparatus for wireless communications, comprising:

means for identifying a system frame number (SFN) rollover time, indicating when a system frame number rolls over from a first value to a second value, wherein the second value is smaller than the first value;

means for stopping hybrid automatic repeat request (HARQ) operation at or near SFN rollover time for one or more HARQs; and

means for restarting uplink HARQ operation from the SFN rollover time.

18. The apparatus of claim 17, further comprising:

means for adjusting the SFN rollover time for one or more user equipments in the system such that the rate of HARQ reset due to SFN rollover is constant in time.

19. The apparatus of claim 17, further comprising:

means for determining a system rollover number M;

wherein the system rollover number is a difference between two consecutive SFN rollover times.

20. The apparatus of claim 19, wherein the system rollover number M is a multiple of the least common multiple of one or more of the HARQ repetition periods of the uplink HARQ operations of the system, wherein the uplink HARQ operations of the system include a frequency division multiplexing mode, and a plurality of uplink-downlink configurations of a time division multiplexing mode.

21. The apparatus of claim 17, wherein the system rollover number M is the largest integer that satisfies a relation

$n=\lceil$

log 2 

M 10 ⌉

,

wherein n is the number of bits defined in the SFN, logg₂ is the logarithm in base two, and the function ┌

.┐

outputs the largest integer inside.

22. The apparatus of claim 17, wherein the means for stopping hybrid automatic repeat request (HARQ) operation at SFN rollover time for one or more HARQs comprises:

means for sending uplink grant message if the roundtrip processing of a message can be finished before SFN rollover time, wherein roundtrip processing of a message comprises transmitting the message and receiving a response to the message.

23. The apparatus of claim 17, wherein the means for stopping hybrid automatic repeat request (HARQ) operation at SFN rollover time for one or more HARQs comprises:

means for sending an uplink grant if the uplink transmission time ends before SFN rollover time.

24. The apparatus of claim 23, further comprising:

means for combining HARQ processes that did not have time to send ACK/NACK before SFN rollover; and

means for sending the combined HARQ process using a process identification (ID) after SFN rollover time;

wherein the process ID is similar to a process ID before the SFN rollover time.

25. A computer-program product for wireless communications, comprising a computer-readable medium having instructions stored thereon, the instructions being executable by one or more processors and the instructions comprising:

instructions for identifying a system frame number (SFN) rollover time, indicating when a system frame number rolls over from a first value to a second value, wherein the second value is smaller than the first value;

instructions for stopping hybrid automatic repeat request (HARQ) operation at or near SFN rollover time for one or more HARQs; and

instructions for restarting uplink HARQ operation from the SFN rollover time.

26. An apparatus for wireless communications, comprising:

at least one processor configured to;

identify a system frame number (SFN) rollover time, indicating when a system frame number rolls over from a first value to a second value, wherein the second value is smaller than the first value;

stop hybrid automatic repeat request (HARQ) operation at or near SFN rollover time for one or more HARQs;

restart uplink HARQ operation from the SFN rollover time; and

a memory coupled to the processor.