System and method for avoiding stall using timer for high-speed downlink packet access system

• US 20030128705A1
• Filed: 12/31/2002
• Published: 07/10/2003
• Est. Priority Date: 01/05/2002
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Yi, Seung June, Lee, So Young, Yeo, Woon Young
• Granted Patent: US 7,522,526 B2
• Time in Patent Office: Days
• US Class Current: 370/394
• CPC Class Codes: H04B 7/0604 with predefined switching scheme
• CPC Class Codes: H04B 7/15507 Relay station based processing for cell extension or control of coverage area, network planning with network coordinated processing with regard to cell extension H04W16/26; network topologies using dedicated repeater stations H04W84/047; terminal devices adapted for relaying to or from an other terminal H04W88/04
• CPC Class Codes: H04B 7/15535 Control of relay amplifier gain amplifier gain control in general H03G3/00; gain control reducing self - or loop interference H04B7/15578
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1841 Resequencing
• CPC Class Codes: H04L 1/1845 Combining techniques, e.g. code combining
• CPC Class Codes: H04L 1/1848 Time-out mechanisms
• CPC Class Codes: H04L 2001/0096 Channel splitting in point-to-point links
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/28 in relation to timing considerations
• CPC Class Codes: H04L 47/34 ensuring sequence integrity, e.g. using sequence numbers
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0042 intra-user or intra-terminal allocation
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0083 symbol-by-symbol
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 28/02 Traffic management, e.g. flow control or congestion control
• CPC Class Codes: H04W 28/14 : using intermediate storage
• CPC Class Codes: H04W 52/143 : Downlink power control
• CPC Class Codes: H04W 52/225 : Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/24 : using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/241 : taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/242 : taking into account path loss
• CPC Class Codes: H04W 52/245 : taking into account received signal strength
• CPC Class Codes: H04W 52/46 : in multi hop networks, e.g. wireless relay networks
• CPC Class Codes: H04W 8/04 : Registration at HLR or HSS [Home Subscriber Server]

Abstract

A method for preventing a stall condition in a terminal of a mobile communications system uses a timer to limit how long data blocks are stored in a reordering buffer. The method includes receiving a data block over a wireless link, determining whether a preceding data block has not been received, storing the received data block in the reordering buffer if a preceding data block has not been received, and then outputting the received block from the buffer when the timer expires. Whether or not a preceding data block is missing is determined based on a comparison of transmission sequence numbers. In other steps of the method, succeeding data blocks are output from the buffer based on expiration of a second timer period. The periods of the timer are advantageously controlled to prevent a wraparound of transmission sequence numbers with respect to data blocks stored in the buffer. If desired, the data blocks may include MAC-hs protocol data units. By limiting the amount of time any one data block stays in the buffer, a stall condition is advantageously prevented. As a result, transmission efficiency and the reliability of received data is substantially improved. The method is ideally suited for use in a medium access layer of a high-speed downlink packet access (HSDPA) mobile communications system, although other uses are contemplated.

Claims

1. A method for processing packet data in a receiver of a communications system, comprising:

receiving a data block having a sequence number;

storing the data block in a reordering buffer;

starting a timer for the reordering buffer if a data block of a preceding sequence number is missing and the timer is not active.

2. The method of claim 1, wherein said timer is the only timer provided for controlling the reordering buffer.

3. The method of claim 1, further comprising:

receiving at least one additional data block after the timer has been started; and

storing the at least one additional data block in the reordering buffer if the data block is not the data block of lowest sequence number among the anticipated missing data blocks.

4. The method of claim 3, further comprising:

removing the additional data block from the reordering buffer when the timer expires, if the additional data block is a data block of sequence number preceding to the sequence number of the data block stored at the time when the timer was started.

5. The method of claim 4, further comprising:

delivering the additional data block to an upper layer.

6. The method of claim 3, further comprising:

removing the additional data block from the reordering buffer when the timer expires, if the additional data block is a data block of sequence number succeeding to the sequence number of the data block stored at the time when the timer was started and if all of the data blocks between the two data blocks are received.

7. The method of claim 6, further comprising:

delivering the additional data block to an upper layer

8. A method for processing packet data in a receiver of a communications system, comprising:

starting a timer for a reordering buffer;

receiving a data block having a sequence number;

storing the data block in the reordering buffer;

removing the data block from the reordering buffer when the timer expires if the sequence number of the data block precedes a sequence number of a data block received and stored in the reordering buffer at a time when the timer was started.

9. The method of claim 8, further comprising:

delivering the data block received in the receiving step when the timer expires, if the sequence number of the data block precedes the sequence number of the data block received and stored in the buffer when the timer was started.

10. The method of claim 8, further comprising:

when the timer expires, delivering to an upper layer the data block which was received and stored in the reordering buffer when the timer was started.

11. The method of claim 8, further comprising:

removing the data block from the reordering buffer when the timer expires if the sequence number of the data block consecutively follows the sequence number of the data block received and stored in the reordering buffer when the timer was started.

12. The method of claim 8, further comprising:

continuing to store the data block received in the receiving step after the timer expires if the sequence number of the data block comes after but does not consecutively follow the sequence number of the data block received and stored in the reordering buffer when the timer was started.

13. The method of claim 12, further comprising:

after the timer expires, determining a data bock in the reordering buffer having a highest sequence number.

14. The method of claim 13, further comprising:

re-starting the timer for the data block having the highest sequence number.

15. A user terminal of a radio communications, comprising:

a reordering buffer for storing a data block having a sequence number;

a timer; and

a controller which starts said timer for the reordering buffer if it receives a data block and another data block of a sequence number preceding to the sequence number of the received data block is missing and the timer is not active.

16. The user terminal of claim 15, wherein said timer is the only timer provided for controlling the reordering buffer.

17. The user terminal of claim 15, wherein said controller controls to receive at least one additional data block after the timer has been started and to store the at least one additional data block in the reordering buffer if the data block is not the data block of lowest sequence number among the anticipated missing data blocks.

18. The user terminal of claim 17, wherein said buffer removes the additional data block from the reordering buffer when the timer expires, if the additional data block is a data block of sequence number preceding to the sequence number of the data block stored at the time when the timer was started.

19. The user terminal of claim 18, wherein said controller controls to deliver the additional data block to an upper layer.

20. The user terminal of claim 17, wherein said controller controls to remove the additional data block from the reordering buffer when the timer expires, if the additional data block is a data block of sequence number succeeding to the sequence number of the data block stored at the time when the timer was started and if all of the data blocks between the two data blocks are received.

21. The user terminal of claim 20, wherein said controller controls to deliver the additional data block to an upper layer.

22. A method for processing packet data in a receiver of a communications system, comprising:

receiving a data block having a sequence number;

starting a timer having an expiration period for a reordering buffer if a data block of preceding sequence number is missing and no timer is active;

storing the data block in the reordering buffer.

23. The method of claim 22, further comprising:

receiving another data block;

storing the data block in the reordering buffer if the data block is not a data block of lowest sequence number of the anticipated missing data blocks.

24. The method of claim 22, further comprising:

receiving another data block;

delivering the data block to the upper layer without storing the data block in the reordering buffer if the data block is a data block of lowest sequence number of the anticipated missing data blocks.

25. The method of claim 24, further comprising:

delivering data blocks consecutive to the data block stored in the buffer to the upper layer;

removing the data blocks delivered to the upper layer from the buffer.

26. The method of claim 25, further comprising:

stopping the timer if all of the data blocks of preceding sequence number are received before the timer expires.

27. The method of claim 26, further comprising:

delivering stored data blocks consecutive to the data block received and stored when the timer started to the upper layer;

removing the data blocks delivered to the upper layer from the buffer.

28. The method of claim 27, further comprising:

starting the timer again, if there remains at least one data block in the buffer.

29. The method of claim 28, further comprising:

stopping the timer, if the data block of highest sequence number in the buffer at a time when the timer started can be delivered to the upper layer before the timer expires.

30. A method for processing packet data in a receiver of a communications system, comprising:

checking data blocks in a reordering buffer when a timer for the reordering buffer becomes inactive; and

restarting a timer for one of the data blocks which will be delivered to the upper layer at the last time among the data blocks stored in the buffer, if there remains at least one data block in the buffer.

31. The method of claim 30, wherein said one of the data blocks corresponds to the data block having a highest sequence number stored in the reordering buffer.

32. A method for processing packet data in a receiver of a communications system, comprising:

receiving data blocks;

storing the data blocks in a reordering buffer;

starting a timer for the reordering buffer; and

delivering the data blocks from the reordering buffer to an upper layer when the timer expires, wherein the delivering step includes delivering the data blocks out of sequence.

33. The method of claim 32, wherein the out-of-sequence delivery is based on sequence numbers of the data blocks.

34. The method of claim 32, wherein the out-of-sequence delivery corresponds to the delivery of the data block in case of having one or more missing data blocks preceding it.

35. The method of claim 34, wherein the data blocks having one or more missing data blocks preceding them are sequentially delivered to an upper layer based on the sequence numbers of the data blocks.