METHOD AND SYSTEM FOR CORRECTING BURST ERRORS IN COMMUNICATIONS NETWORKS, RELATED NETWORK AND COMPUTER-PROGRAM PRODUCT

• US 20100122127A1
• Filed: 01/15/2010
• Published: 05/13/2010
• Est. Priority Date: 04/04/2005
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Convertino, Gabriella, Oliva, Silvio Lucio
• Granted Patent: US 7,962,834 B2
• Time in Patent Office: Days
• US Class Current: 714/704
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27

Abstract

The errors that may occur in transmitted numerical data on a channel affected by burst errors, are corrected via the operations of: ordering the numerical data in blocks each comprising a definite number of data packets; generating for each block a respective set of error-correction packets comprising a respective number of correction packets, the respective number identifying a level of redundancy for correcting the errors; and modifying dynamically the level of redundancy according to the characteristics of the bursts and of the correct-reception intervals between two bursts. Preferential application is on local networks, such as W-LANs for use in the domestic environments.

Claims

1. A method for correcting burst errors in a transmission of data in a communications network, the method comprising:

under control of a transmitter device that transmits data blocks to a receiver device via the communications network, the data blocks each including a definite number of respective data packets,

transmitting one or more first data blocks to the receiver device via the communications network;

dynamically determining a level of redundancy for correcting burst errors in a transmission of one or more second data blocks to the receiver device according to characteristics of bursts and correct-reception intervals of the transmitted one or more first data blocks; and

for each of the one or more second data blocks,

generating a respective set of error-correction packets comprising a respective number of correction packets, said respective number based on the dynamically determined level of redundancy; and

transmitting to the receiver device via the communications network the respective data packets and the respective set of error-correction packets.

2. The method of claim 1, further comprising receiving from the receiver device information indicative of the characteristics of bursts and correct-reception intervals, and dynamically determining the level of redundancy based on the received information.

3. The method of claim 2, wherein the information is received from the receiver device in one or more transmission reports generated by the receiving device.

4. The method of claim 1, wherein the respective set of error-correction packets is a set of forward-error correction packets.

5. The method of claim 1, further comprising identifying the bursts as sequences of packets that start with a lost packet or a rejected packet, do not contain any occurrence of a given number of consecutively received packets, and conclude with a lost packet or a rejected packet.

6. The method of claim 5, further comprising identifying the given number as the minimum distance in received packets between two lost or rejected packets so that a loss can be considered as belonging to a correct-reception interval.

7. The method of claim 1, wherein the dynamically determining the level of redundancy includes dynamically determining the level of redundancy according to at least one parameter chosen between:

a density of the bursts, defined as fraction of lost or rejected data packets during the bursts; and

a density of the correct-reception intervals, defined as fraction of lost or rejected data packets within correct-reception intervals between successive bursts.

8. The method of claim 1, wherein the dynamically determining includes dynamically determining the level of redundancy according to a packet error rate, defined as a ratio between a total number of lost packets and a total number of expected packets for transmission in a given time interval.

9. The method according to claim 8, further comprising:

receiving transmission reports of said packets; and

detecting a difference in a cumulative number of lost packets as a number of lost packets during one of said time intervals.

10. The method of claim 8, further comprising:

receiving transmission reports of said packets; and

detecting a difference in progressive numbers between the last packets of two successive reports as the number of expected packets during the interval.

11. The method of claim 8, wherein duplicated packets are not counted as received packets.

12. The method of claim 8, wherein a counting a packet that is rejected on account of delayed arrival as a lost packet.

13. The method of claim 1, further comprising subjecting the respective data packets corresponding to the data blocks to interleaving.

14. The method of claim 1, further comprising:

identifying the bursts as sequences of packets that start with a lost packet or a rejected packet, do not contain any occurrence of a given number of consecutively received packets, and conclude with a lost packet or a rejected packet; and

determining for each of the one or more second data blocks the definite number of respective data packets as a sum of a mean length of the bursts and of the given number of consecutively received packets minus a mean number of losses of packets in a burst, so that the respective number of correction packets is adjusted based on the mean number of losses of packets in a burst.

15. The method of claim 14, further comprising determining the respective number of correction packets in a way proportional to a packet error rate.

16. The method of claim 15, further comprising determining the respective number of correction packets according to the following rules:

when the packet error rate is lower than a given threshold, error-correction packets are not added;

when the packet error rate is comprised between two percentage values A and B, with B>

A, in a block of n packets, B % error-correction packets are added.

17. The method of claim 1, further comprising:

identifying the bursts as sequences of packets that start with a lost packet or a rejected packet, do not contain any occurrence of a given number of consecutively received packets, conclude with a lost packet or a rejected packet;

subjecting the data packets corresponding to the data blocks to interleaving; and

determining an interleaving depth as a sum of a length of the correct-reception interval and a burst length divided by the burst length.

18. A system for correcting burst errors in the transmission of data on a transmission channel affected by burst errors, the system comprising:

ordering means for ordering the data in blocks each comprising a definite number of data packets;

generating means for generating for each of the blocks a respective set of error-correction packets comprising a respective number of correction packets, the respective number identifying a level of redundancy for correcting the burst errors; and

modifying means for dynamically modifying the level of redundancy according to characteristics of the burst errors and of correct-reception intervals between two of the burst errors.

19. The system of claim 18, wherein the modifying means include means for dynamically modifying the level of redundancy according to at least one parameter chosen between:

a density of the burst errors, defined as fraction of lost or rejected data packets during the burst errors; and

a density of the correct-reception intervals, defined as fraction of lost or rejected data packets within correct-reception intervals between successive burst errors.

20. The system of claim 18, wherein the modifying means include means for dynamically modifying the level of redundancy according to a packet error rate, defined as a ratio between a total number of lost packets and a total number of expected packets for transmission in a given time interval.

21. The system of claim 20, further comprising:

further generating means for generating, at time intervals, transmission reports of the packets; and

means for detecting a difference in a cumulative number of lost packets as a number of lost packets during one of the time intervals.

22. The system of claim 20, further comprising:

further generating means for generating, at time intervals, transmission reports of the packets; and

means for detecting a difference in progressive numbers between the last packets of two successive reports as the number of expected packets during the interval.

23. A communications network, comprising:

at least one channel for transmission of data affected by burst errors; and

a system for correcting the burst errors, the system including;

ordering means for ordering the data in blocks each comprising a definite number of data packets;

generating means for generating for each of the blocks a respective set of error-correction packets comprising a respective number of correction packets, the respective number identifying a level of redundancy for correcting the errors; and

modifying means for dynamically modifying the level of redundancy according to characteristics of the burst errors and of correct-reception intervals between two of the burst errors.

24. The network of claim 23, wherein the network is a wireless local-area network.

25. The network of claim 23, wherein the modifying means include means for dynamically modifying the level of redundancy according to at least one parameter chosen between:

a density of the burst errors, defined as fraction of lost or rejected data packets during the burst errors; and

a density of the correct-reception intervals, defined as fraction of lost or rejected data packets within correct-reception intervals between successive burst errors.

26. The network of claim 23, wherein the modifying means include means for dynamically modifying the level of redundancy according to a packet error rate, defined as a ratio between a total number of lost packets and a total number of expected packets for transmission in a given time interval.

27. The network of claim 26, further comprising:

further generating means for generating, at time intervals, transmission reports of the packets; and

means for detecting a difference in a cumulative number of lost packets as a number of lost packets during one of the time intervals.

28. The network of claim 26, further comprising:

further generating means for generating, at time intervals, transmission reports of the packets; and

means for detecting a difference in progressive numbers between the last packets of two successive reports as the number of expected packets during the interval.

29. A computer-readable medium having contents that cause a computing device to correct burst errors in a transmission of data according to a method comprising the operations of:

ordering the data in blocks each comprising a definite number of data packets;

generating for each of the blocks a respective set of error-correction packets comprising a respective number of correction packets, the respective number identifying a level of redundancy for correcting the errors; and

dynamically modifying the level of redundancy according to characteristics of the burst errors and of correct-reception intervals between two of the burst errors.

30. The computer-readable medium of claim 29, further comprising generating the set of error-correction packets as set of forward-error correction packets.

31. The computer-readable medium of claim 29, wherein the modifying operation includes dynamically modifying the level of redundancy according to at least one parameter chosen between:

a density of the burst errors, defined as fraction of lost or rejected data packets during the burst errors; and

a density of the correct-reception intervals, defined as fraction of lost or rejected data packets within correct-reception intervals between successive burst errors.

32. The computer-readable medium of claim 29, wherein the modifying operation includes dynamically modifying the level of redundancy according to a packet error rate, defined as a ratio between a total number of lost packets and a total number of expected packets for transmission in a given time interval.

33. The computer-readable medium of claim 32, wherein the method further comprises:

generating, at time intervals, transmission reports of the packets; and

detecting a difference in a cumulative number of lost packets as a number of lost packets during one of the time intervals.

34. The computer-readable medium of claim 32, wherein the method further comprises:

generating, at time intervals, transmission reports of the packets; and

detecting a difference in progressive numbers between the last packets of two successive reports as the number of expected packets during the interval.

35. The computer-readable medium of claim 29, wherein the method further comprises:

identifying the burst errors as sequences of packets having the following characteristics;

i) they start with a lost packet or rejected packet;

ii) they do not contain any occurrence of a given number of consecutively received packets;

iii) they conclude with a lost packet or rejected packet; and

determining the definite number of data packets as a sum of a mean length of the burst errors and of the given number of consecutively received packets minus a mean number of losses of packets in a burst, so that the respective number of correction packets is adjusted based on the mean number of losses of packets in a burst.

36. The computer-readable medium of claim 35, wherein the method further comprises determining the respective number of correction packets in a way proportional to a packet error rate.

37. The computer-readable medium of claim 36, further comprising determining the respective number of correction packets according to the following rules:

when the packet error rate is lower than a given threshold, error-correction packets are not added;

when the packet error rate is comprised between two percentage values A and B, with B>

A, in a block of n packets, B % error-correction packets are added.