Error correcting apparatus

• US 6,615,386 B2
• Filed: 01/03/2001
• Issued: 09/02/2003
• Est. Priority Date: 02/17/2000
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yano, Tetsuya, Obuchi, Kazuhisa
• Primary Examiner(s): TU, CHRISTINE TRINH LE
• Application Number:
  US09/753,884
• Publication Number:
  US 20010020287A1
• Time in Patent Office: 972 Days
• Field of Search: 714/746, 714/752, 714/780, 714/822, 714/758, 714/779, 714/786, 714/799
• US Class Current: 714/780
• CPC Class Codes: H03M 13/3723 using means or methods for the initialisation of the decoder
• CPC Class Codes: H03M 13/45 Soft decoding, i.e. using symbol reliability information H03M13/41 takes precedence
• CPC Class Codes: H03M 13/6306 Error control coding in combination with Automatic Repeat reQuest [ARQ] and diversity transmission, e.g. coding schemes for the multiple transmission of the same information or the transmission of incremental redundancy H03M13/3761, H03M13/3769 and H03M13/635 take precedence
• CPC Class Codes: H04L 1/0046 Code rate detection or code type detection H04L1/0038 takes precedence; detection of the data rate H04L25/0262; for packet format H04L1/0091
• CPC Class Codes: H04L 1/0067 Rate matching H04L1/0013 and H04L1/08 take precedence
• CPC Class Codes: H04L 1/0075 Transmission of coding parameters to receiver H04L1/0023 takes precedence
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence

Abstract

Disclosed herein is an error correcting apparatus for receiving a signal subjected to a repetition processing in which a part of bits of an error-correction code train are repeatedly transmitted, and decoding the received signal so as to be restored to the original data. A repetition rate calculator calculates the repetition rate of the received signal subjected to the repetition processing, a soft decision data cut-off position decision unit decides the position at which a part of the soft decision data is cut off from the soft decision data which is generated by the repetition regenerator, on the basis of the repetition rate Rr, and a bit selector cuts off the part of the soft decision data at the decided cut-off position and inputs the cut part into a soft decision error-correction decoder.

Claims

1. An error correcting apparatus for receiving a signal subjected to a repetition processing in which a part of bits of an error-correction code train are repeatedly transmitted, and decoding said received signal so as to be restored to the original data train, said error-correction apparatus comprising:

a receiver/demodulator unit for receiving and demodulating a signal subjected to the repetition processing in which a part of bits of the error-correction code train are repeatedly transmitted, and outputting a soft decision data train;

a soft decision data train generator for adding a soft decision data which corresponds to the repeatedly transmitted bits, so as to generate a soft decision data train which corresponds to the original error-correction code train; and

a soft decision error-correction decoder for restoring said soft decision data train to said original data train;

wherein said soft decision data train generator includes;

a repetition regenerator for obtaining the positions of said bits which are repeatedly transmitted due to said repetition processing, and adding a soft decision data which corresponds to said positions so as to generate said soft decision data train which corresponds to said original error-correction code train;

a repetition rate calculator for calculating the repetition rate of said received signal subjected to said repetition processing;

a first soft decision data cut-off position decision unit for deciding a position at which a part of said soft decision data which is to be input into said soft decision error-correction decoder is cut off from said soft decision data which is generated by said repetition regenerator, on the basis of said repetition rate; and

a first soft decision data cutting means for cutting off said part of said soft decision data at the decided cut-off position and inputting the cut part into said soft decision error-correction decoder.

2. An error-correcting apparatus according to claim 1, wherein said repetition rate calculator calculates said repetition rate on the basis of the number N of bits of the data before said repetition processing and the number Δ

N of bits which are repeated due to said repetition processing, the numbers N and Δ

N being notified of from a communication party.

3. An error correcting apparatus according to claim 1, wherein said repetition regenerator obtains said positions of said bits which are repeatedly transmitted by executing a repetition algorithm on the basis of the number N of bits of the data before said repetition processing and the number Δ

N of bits which are repeated due to said repetition processing, the numbers N and Δ

N being notified of from a communication party.

4. An error correcting apparatus according to claim 1, further comprising:

an average value calculator for calculating the average value of said soft decision data which is demodulated by said demodulator unit;

a second soft decision data cut-off position decision unit for deciding a position at which a part of said soft decision data which is to be input into said repetition regenerator is cut off from the demodulated soft decision data, on the basis of said average value;

a second soft decision data cutting means for cutting off a part of said soft decision data of a predetermined number of bits from said demodulated soft decision data on the basis of the decided cut-off position and inputting the cut part into said repetition regenerator; and

a comparator for comparing said repetition rate with a preset value;

wherein said first soft decision data cutting means cuts off a plural upper bits from said soft decision data which is generated by said repetition regenerator and inputs said bits into said soft decision error-correction decoder when said repetition rate is larger than said preset value, while cutting off plural lower bits and inputting said bits into said soft decision error-correction decoder when said repetition rate is smaller than said preset value.

5. An error correcting apparatus according to claim 1, further comprising:

an average value calculator for calculating the average value of said soft decision data which is demodulated by said demodulator unit; and

a comparator for comparing said repetition rate with a preset value;

wherein said first soft decision data cut-off position decision unit decides a position at which a part of the soft decision data which is to be input into said soft decision error-correction decoder is cut off from said soft decision data which is generated by said repetition regenerator, on the basis of said average value and the result of comparison between said repetition rate and said preset value.

6. An error correcting apparatus for receiving a signal subjected to a repetition processing in which a part of bits of an error-correction code train are repeatedly transmitted, and decoding said received signal so as to be restored to the original data train before error-correction coding, said error-correction apparatus comprising:

a receiver/demodulator unit for receiving and demodulating a signal subjected to the repetition processing in which a part of bits of said error-correction code train are repeatedly transmitted, and outputting a soft decision data train;

a soft decision data train generator for adding a soft decision data which corresponds to the repeatedly transmitted bits, so as to generate a soft decision data train which corresponds to the original error-correction code train; and

a soft decision error-correction decoder for restoring said soft decision data train to said original data train;

wherein said soft decision data train generator includes;

a repetition regenerator for obtaining the positions of said bits which are repeatedly transmitted due to said repetition processing, and adding said soft decision data which corresponds to said positions so as to generate said soft decision data train which corresponds to said original error-correction code train;

an average value calculator for calculating the first average value of said soft decision data which is output from said repetition regenerator;

a first soft decision data cut-off position decision unit for deciding a position at which a part of said soft decision data which is to be input into said soft decision error-correction decoder is cut off from said soft decision data which is generated by said repetition regenerator, on the basis of said first average value; and

a first soft decision data cutting means for cutting off said part of said soft decision data at the decided cut-off position and inputting the cut part into said soft decision error-correction decoder.

7. An error correcting apparatus according to claim 6, further comprising:

an average value calculator for calculating the second average value of said soft decision data which is demodulated by said demodulator unit;

a second soft decision data cut-off position decision unit for deciding a position at which a part of said soft decision data which is to be input into said repetition regenerator is cut off from the demodulated soft decision data, on the basis of said second average value;

a second soft decision data cutting means for cutting off a part of said soft decision data of a predetermined number of bits from said demodulated soft decision data on the basis of the decided cut-off position and inputting the cut part into said repetition regenerator; and

a comparator for comparing said first average value of said soft decision data which is output from said repetition regenerator with a preset value;

wherein said first soft decision data cutting means cuts off plural upper bits from said soft decision data which is generated by said repetition regenerator and inputs said bits into said soft decision error-correction decoder when said first average value is larger than said preset value, while cutting off plural lower bits and inputting said bits into said soft decision error-correction decoder when said first average value is smaller than said preset value.

8. An error correcting apparatus according to claim 6, further comprising:

an average value calculator for calculating the second average value of said soft decision data which is demodulated by said demodulator unit; and

a comparator for comparing said first average value of said soft decision data which is output from said repetition regenerator with a preset value;

wherein said first soft decision data cut-off position decision unit decides a position at which a part of the soft decision data which is to be input into said soft decision error-correction decoder is cut off from said soft decision data which is generated by said repetition regenerator, on the basis of the result of comparison between said first average value and said preset value, and said second average value.