Method and apparatus for error detection in a communication system

• US 20100153828A1
• Filed: 11/04/2009
• Published: 06/17/2010
• Est. Priority Date: 11/04/2008
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Inventors: Zottmann, Andreas Bernhard, De Lind Van Wijngaarden, Adriaan J.
• Granted Patent: US 8,892,983 B2
• Time in Patent Office: Days
• US Class Current: 714/807
• CPC Class Codes: H03M 13/09 Error detection only, e.g. using cyclic redundancy check [CRC] codes or single parity bit
• CPC Class Codes: H03M 13/611 Specific encoding aspects, e.g. encoding by means of decoding
• CPC Class Codes: H03M 13/6522 Intended application, e.g. transmission or communication standard
• CPC Class Codes: H03M 13/6527 IEEE 802.11 [WLAN]
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0076 Distributed coding, e.g. network coding, involving channel coding coding in both space and time H04L1/0618; cooperative diversity H04B7/022
• CPC Class Codes: H04L 1/0084 Formats for payload data

Abstract

A method processes a data packet in a first sequence of disjoint original segments of the same length. The method includes modifying a first of the original segments of the first sequence by modifying one or more symbols therein. A start of the data packet is located in the first of the original segments and is positioned after a first digital data symbol therein. The method also includes modifying a last of the original segments of the first sequence by modifying one or more digital data symbols therein. An end of the data packet is located in the last of the original segments and is located before the last digital data symbol therein. The method also includes determining a remainder sequence by effectively performing a polynomial division on a second sequence of disjoint segments that are derived from the first sequence. Each segment of the second sequence corresponds to and is derived from one of the original segments of the first sequence. The segments of the second sequence have the length of the original segments of the first sequence. A first of the derived segments of the second sequence is the modified first of the original segments. A last of the derived segments of the second sequence is derived from the modified last of the original segments.

Claims

1. A method of processing a data packet located in a first sequence of disjoint original segments, each original segment of the first sequence having the same length, comprising:

modifying a first of the original segments of the first sequence by modifying one or more symbols therein, a start of a data packet being located in the first of the original segments and being after a first symbol therein;

modifying a last of the original segments of the first sequence by modifying one or more symbols therein, an end of the data packet being located in the last of the original segments and being before the last symbol therein; and

determining a remainder by performing a polynomial division on a second sequence of disjoint derived segments, each segment of the second sequence corresponding to and being derived from one of the original segments, the segments of the second sequence having the length of the original segments, a first of the derived segments of the second sequence being the modified first of the original segments, a last of the derived segments of the second sequence being the modified last of the original segments.

2. The method of claim 1, wherein each derived segment that does not include the start or end of the data packet is equal to the corresponding one of the original segments.

3. The method of claim 1, wherein the modifying steps include masking portions of the original segments outside of the data packet such that said portions will contribute in a predetermined amount to the remainder determined by the polynomial division.

4. The method of claim 1, wherein the modifying a first of the original segments modifies symbols at the start of the data packet.

5. The method of claim 4, wherein the modifying steps include masking portions of the original segments outside of the data packet such that said masked portions will contribute in a predetermined amount to the remainder determined by the polynomial division.

6. The method of claim 1, wherein the modifying of a last of the original segments modifies symbols at the end of the data packet.

7. The method of claim 6, wherein the modifying steps include masking portions of the original segments outside of the data packet such that said masked portions will not contribute to the remainder determined by the polynomial division when a cyclic redundancy check of the data packet vanishes.

8. The method of claim 1, further comprising:

producing a third sequence by performing a symbol-by-symbol subtraction of a sequence of symbols from the first sequence such that a data packet located in the third sequence becomes a valid codeword of an error control code that is based on a polynomial division.

9. The method of claim 8, wherein the sequence of symbols is found from the remainder determined by the performing a polynomial division on a second sequence.

10. The method of claim 1, further comprising:

writing an evaluated value of a cyclic redundancy check for the data packet into a specific one of the segments of the first sequence in response to the end of the data packet being in the specific one of the segments of the first sequence.

11. The method of claim 10,

wherein the modifying further includes receiving a number indicative of the location of the end of the packet in the specific one of the segments of the first sequence;

and

wherein the writing includes determining a location to write the evaluated value based on the received number.

12. A method of processing a sequence of disjoint data segments of equal length, the sequence including a particular data packet, comprising:

masking a portion of one of the data segments, a portion of the particular data packet being in the one of the data segments and being outside of the masked portion;

modifying a start and/or end of the particular data packet; and

calculating a cyclic redundancy check for the particular data packet based on the masked segment and the modified particular data packet.

13. The method of claim 12, comprising comparing the calculated cyclic redundancy check to zero.

14. The method of claim 13, wherein the calculating a cyclic redundancy check comprises calculating a check sequence value based at least partially on another cyclic redundancy check transmitted with the data packet.

15. The method of claim 12, comprising identifying an end-of-packet within the specific one of the data segments.

16. The method of claim 12, comprising inverting one or more symbols at the start of the data packet.

17. The method of claim 12, comprising inverting one or more symbols at the end of the data packet.

18. A system for processing a data packet located in a first sequence of disjoint original segments, each original segment of the first sequence having the same length, comprising:

a masking unit configured to modify one or more symbols in a first of the original segments of the first sequence where a start of the data packet is in the first of the original segments and is after a first symbol therein, the masking unit being configured to modify one or more symbols in a last of the original segments of the first sequence where an end of the data packet is located in the last of the original segments and is before a last symbol therein; and

cyclic redundancy check calculation unit configured to determine a remainder by performing a polynomial division on a second sequence of disjoint consecutive segments, each segment of the second sequence corresponding to and being derived from one of the original segments, the segments of the second sequence having the length of the original segments, the first of the derived segments of the second sequence being the modified first of the original segments, the last of the derived segments of the second sequence being the modified last of the original segments.

19. The system of claim 18, wherein the masking unit is configured to mask portions of the original segments outside of the data packet such that said portions will not contribute to the remainder determined by the polynomial division when a cyclic redundancy check of the data packet vanishes.

20. The system of claim 19, wherein the masking unit is configured to modify the first of the original segments by modifying symbols at the start of the data packet and to modify the last of the original segments by modifying symbols at the end of the data packet.