Dynamic forward error correction

• US 6,314,535 B1
• Filed: 05/18/1999
• Issued: 11/06/2001
• Est. Priority Date: 05/18/1999
• Status: Expired

• Current Assignee: Intel Corporation
• Original Assignee: Xircom Wireless Incorporated
• Inventors: Barabash, Darrell W., Morris, Russell A.
• Primary Examiner(s): Baker, Stephen M.
• Application Number:
  US09/314,578
• Time in Patent Office: 903 Days
• Field of Search: 714/704, 714/705, 714/706, 714/707, 714/708, 714/774, 714/776, 370/468
• US Class Current: 714/708
• CPC Class Codes: H03M 13/03 Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
• CPC Class Codes: H03M 13/35 Unequal or adaptive error protection, e.g. by providing a different level of protection according to significance of source information or by adapting the coding according to the change of transmission channel characteristics
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/20 using signal quality detector

Abstract

A forward error correction (FEC) method is provided including an FEC dynamic central station and a plurality of FEC dynamic remote stations that transmit bearer data and corresponding error correction data therebetween during a plurality of time frames. The error rate of the communication channel is measured and the amount of error correction data transmitted is accordingly and dynamically adjusted, so that the minimum amount of overhead required to effectively transmit the error correction data is used.

Claims

1. A method of selecting an error correction algorithm in a communications system, the method comprising:

dividing each time frame of a multi-frame into a plurality of time slots;

determining an error rate level of a communication channel based on a plurality of bearer data packets when received during said multi-frame;

selecting an error correction algorithm from a plurality of error correction algorithms taking into account said error rate level;

determining the dynamic quality of said communication channel; and

adjusting the number of time frames in a multi-frame based on said dynamic quality.

2. The method of claim 1, wherein said plurality of bearer data packets comprises traffic data.

3. The method of claim 2, wherein said error correction algorithm has an overhead level, and wherein the amount of said traffic data is inversely varied with said overhead.

4. The method of claim 1, and wherein said error rate level determination comprises correcting said plurality of bearer data packets and detecting a number of defective bearer data packets to obtain a current block error rate (BLER) level, and wherein said error correction algorithm determination is based on said current BLER level.

5. The method of claim 4, wherein said error correction algorithm selection comprises setting a minimum BLER threshold level and a maximum BLER threshold level to create an acceptable BLER range, selecting a current error correction algorithm if said acceptable BLER range includes said current BLER level and selecting an error correction algorithm different from said current error correction algorithm if said acceptable BLER range does not include said current BLER level.

6. The method of claim 5, wherein said plurality of error correction algorithms comprise differing overhead levels, and said error correction algorithm determination further comprises selecting an error correction algorithm with a next lower overhead than that of said current error correction algorithm if said current BLER level is below said minimum BLER threshold level and selecting an error correction algorithm with a next higher overhead than that of said current error correction algorithm if said current BLER level is above said maximum BLER threshold level.

7. The method of claim 1, wherein said error rate level determination comprises detecting a number of bit errors in said plurality of bearer data packets to obtain a bit error rate (BER) level, and wherein said error rate level determination is based on said current BER level.

8. The method of claim 7, wherein said error correction algorithm selection comprises setting at least one BER threshold level to create a plurality of BER ranges corresponding to the plurality of error correction algorithmns, and selecting an error correction algorithm that corresponds to the BER range that includes the current BER level.

9. The method of claim 1, wherein each bearer data packet of said plurality of bearer data packets is respectively received during a time slot of said each time frame of said multi-frame, and wherein said error correction algorithm selection comprises selecting said error correction algorithm during the last time frame of said multi-frame.

10. The method of claim 1, wherein said plurality of error correction algorithms includes an algorithm which, when used, does not correct any errors.

11. The method of claim 1, wherein said plurality of error correction algorithms includes an algorithm which, when used, does not correct any errors, a low-level error correction algorithm and a high-level error correction algorithm.

12. The method of claim 1, wherein said plurality of bearer data packets are wirelessly transmitted between a central station and a remote station.