Error detection methods in wireless communication systems

• US 7,162,675 B2
• Filed: 04/05/2002
• Issued: 01/09/2007
• Est. Priority Date: 04/05/2002
• Status: Expired due to Term

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Sampath, Ashwin, Khan, Farooq Ullah, Das, Arnab, Su, Hsuan-Jung
• Primary Examiner(s): Torres, Joseph
• Application Number:
  US10/115,967
• Publication Number:
  US 20030192003A1
• Time in Patent Office: 1,740 Days
• Field of Search: 714/751, 714/774, 714/776
• US Class Current: 714/751
• 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 13/2975 Judging correct decoding, e.g. iteration stopping criteria
• CPC Class Codes: H03M 13/39 Sequence estimation, i.e. using statistical methods for the reconstruction of the original codes
• CPC Class Codes: H03M 13/41 using the Viterbi algorithm or Viterbi processors
• CPC Class Codes: H04L 1/0051 Stopping criteria
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 1/0065 Serial concatenated codes
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]

Abstract

The error detection method includes decoding a portion of each control channel that is simultaneously received by a user equipment (UE) in a wireless communication system. The UE is provided with techniques to determine if one or more of the control channels were successfully received during the decoding step. If more than one control channel was successfully received, the method selects only one of the successfully received control channels based on calculated path metric differences (PMD) that serve as a “tie-breaking” mechanism to select the correct control channel for a particular UE.

Claims

1. A method of detecting errors in control channels of a wireless communication system, comprising:

decoding at least a portion of each control channel;

determining if one or more control channels were successfully received during the decoding step; and

selecting one of the successfully received control channels based on at least one calculated metric including at least one path metric difference (PMD);

wherein said step of selecting includes,

calculating a path metric difference (PMD) metric for each control channel determined as successfully received, when more than one control channel are successfully received as determined by said determining step, and

selecting one of the successfully received control channels based on the calculated PMDs, wherein said step of calculating includes,

calculating at least one of a minimum path metric difference (MPMD) metric, an aggregate path metric difference (APMD) metric, and a frequency path metric difference (FPMD) metric for each successfully received control channel, wherein said step of calculating the at least a frequency path metric difference (FPMD) metric includes,

performing Viterbi decoding to determine a winning path metric at each of a plurality of states, and

counting a number of times by which the winning path at each state came within a threshold value of beating a competing path at said each state, wherein the winning path having the lowest frequency of coming within said threshold corresponds to the one successfully received control channel selected in the selecting step.

2. The method of claim 1, wherein said step of determining includes performing a cyclic redundancy check.

3. The method of claim 1, wherein said step of determining includes performing a Yamamoto-Itoh (YI) decoding algorithm.

4. The method of claim 3, wherein said step of determining includes using a parity check code appended to each portion of each control channel in conjunction with the YI algorithm to determine if one or more control channels were successfully received during the decoding step.

5. The method of claim 3, wherein said step of determining includes using a scrambling group code identifier (SCGI) code appended to each portion of each control channel in conjunction with the YI algorithm in order to determine if one or more control channels were successfully received during the decoding step.

6. The method of claim 1, wherein said step of determining includes using a parity check code appended to each portion of each control channel to determine if one or more control channels were successfully received during the decoding step.

7. The method of claim 1, wherein said step of determining includes using a scrambling group code identifier (SCGI) code appended to each portion of each control channel to determine if one or more control channels were successfully received during the decoding step.

8. The method of claim 1, wherein said step of calculating an MPMD metric comprises:

performing Viterbi decoding to determine a winning path metric at each of a plurality of states, and

retaining a minimum difference metric value by which the winning path at each state beat a competing path at said each state, wherein the winning path having the largest minimum difference metric value corresponds to the one successfully received control channel selected in the selecting step.

9. The method of claim 1, wherein said step of calculating an APMD metric comprises:

performing Viterbi decoding to determine a winning path metric at each of a plurality of states, and

retaining an aggregate sum of the PMDs by which the winning path at each state beat a competing path at said each state, wherein the winning path having the largest aggregate sum corresponds to the one successfully received control channel selected in the selecting step.

10. A method of detecting errors in control channels of a wireless communication system, comprising:

decoding at least a portion of each control channel;

performing a Yamamoto-Itoh (YI) decoding algorithm to determine if one or more control channels were successfully received during the decoding step; and

selecting one of the successfully received control channels determined by the YI algorithm based on at least one calculated metric, the at least one calculated metric including at least one path metric difference (PMD);

wherein step of selecting includes,

calculating a path metric difference (PMD) metric for each control channel, when more than one control channel are successfully received as determined by said YI algorithm, and

selecting one of the successfully received control channels based on the PMDs calculated, wherein said step of calculating includes,

calculating at least one of a minimum path metric difference (MPMD) metric, an aggregate path metric difference (APMD) metric, and a frequency path metric difference (FPMD) metric for each successfully received control channel, and wherein said step of calculating a frequency path metric difference (FPMD) metric includes,

performing Viterbi decoding to determine a winning path metric at each of a plurality of states, and

counting a number of times by which the winning path at each state came within a threshold value of beating a competing path at said each state, wherein the winning path having the lowest frequency of coming within said threshold corresponds to the one successfully received control channel selected in the selecting step.

11. The method of claim 10, wherein said step of calculating an MPMD metric comprises:

performing Viterbi decoding to determine a winning path metric at each of a plurality of states, and

retaining a minimum difference metric value by which the winning path at each state beat a competing path at said each state, wherein the winning path having the largest minimum difference metric value corresponds to the one successfully received control channel selected in the selecting step.

12. The method of claim 10, wherein said step of calculating an APMD metric comprises:

performing Viterbi decoding to determine a winning path metric at each of a plurality of states, and

retaining an aggregate sum of the PMD'"'"'s by which the winning path at each state beat a competing path at said each state, wherein the winning path having the largest aggregate sum corresponds to the one successfully received control channel selected in the selecting step.