Forward error correction for broadcast/multicast service

• US 20060072538A1
• Filed: 09/28/2005
• Published: 04/06/2006
• Est. Priority Date: 09/29/2004
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Raith, Alex Krister
• Granted Patent: US 8,406,211 B2
• Time in Patent Office: Days
• US Class Current: 370/349
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data

Abstract

An error detection unit performs erasure decoding for physical layer packets and an assembler assembles the received data into higher layer packets. Higher layer packets that are incomplete are not erased if the higher layer packets contain some data indicated as valid by the error detection unit. In the case of incomplete packets, the data is labeled by assigning a value to a reliability attribute for the data to enable the decoder to discriminate between valid and invalid data in the same packet. The decoder is modified to use “dimmed” data from the incomplete packets to perform decoding.

Claims

1. A method of re-assembling higher layer packets received by a mobile station and containing coded packet data protected by a forward error correction code, said method comprising:

receiving packet data encapsulated in lower layer packets from a network over an air interface;

re-assembling the received packet data into higher layer packets;

detecting errors in said lower layer packets;

labeling data in partial higher layer packets based on detected errors in said lower layer packets by assigning a first attribute value to a reliability attribute for invalid data in partial higher layer packets and a second attribute value to said reliability attribute for valid data in the same partial higher layer packets.

2. The method of claim 1 wherein said first attribute value indicates invalid data, and wherein said second attribute value indicates valid data.

3. The method of claim 1 wherein said first attribute value indicates invalid data, and wherein said second attribute value indicates dimmed data.

4. The method of claim 3 further comprising assigning a third attribute value to said reliability attribute for valid data in complete higher layer packets.

5. The method of claim 4 wherein said third attribute value indicates valid data.

6. The method of claim 1 further comprising decoding the coded packet data contained in the application layer packets using valid data in said partial higher layer packets.

7. The method of claim 1 wherein said higher layer packets include a header not protected by said forward error correction code, and further comprising detecting errors in said header.

8. The method of claim 7 wherein detecting errors in said header comprises detected unexpected values in one or more header fields.

9. The method of claim 8 further comprising repairing headers with detected errors.

10. The method of claim 9 further comprising verifying the repaired headers.

11. The method of claim 10 wherein verifying the repaired headers includes using a CRC generated on said header to verify the repaired headers.

12. A mobile station comprising:

a receiver to receive coded packet data encapsulated in lower layer packets from

a mobile network over an air interface;

an error detection unit to detect valid lower layer packets;

an assembler to assemble higher layer packets from said received packet data and to label said packet data in said higher layer packets based on the results of said error detection by said error detection unit, wherein said labeling comprises assigning a first attribute value to a reliability attribute for invalid data in partial higher layer packets and a second attribute value to said reliability attribute for valid data in the same partial higher layer packets..

13. The mobile station of claim 12 wherein said first attribute value indicates invalid data, and wherein said second attribute value indicates valid data.

14. The mobile station of claim 12 wherein said first attribute value indicates invalid data, and wherein said second attribute value indicates dimmed data.

15. The mobile station of claim 14 wherein said assembler assigns a third attribute value to said reliability attribute for valid data in complete higher layer packets.

16. The mobile station of claim 15 wherein said third attribute value indicates valid data.

17. The mobile station of claim 12 further comprising a decoder to decode the coded packet data contained in the higher layer packets using valid data in said partial higher layer packets.

18. The mobile station of claim 12 further comprising an error detection and header repair unit to detect errors in said header of said higher layer packets.

19. The mobile station of claim 18 wherein said error detection and header repair unit detects errors in said header by detecting unexpected values in one or more header fields.

20. The mobile station of claim 19 wherein the error detection and header repair unit repairs headers with detected errors.

21. The mobile station of claim 20 wherein the error detection and header repair unit verifies the repaired headers using a CRC generated on said headers.