Block turbo decoder design
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Block Turbo Decoder Design. Hu Dongwei. Error Correcting Codes. Classic Block Codes BCH RS RM Convolutional Codes (Viterbi)

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Block Turbo Decoder Design

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Block turbo decoder design

Block Turbo Decoder Design

Hu Dongwei


Error correcting codes

Error Correcting Codes

  • Classic Block Codes BCH RS RM

  • Convolutional Codes (Viterbi)

  • Turbo Codes Parallel Concatenated Convolutional Codes Serial Concatenated Block Codes


Block turbo coding

Block Turbo Coding


Ml decoding

ML decoding

即寻找一个与接收信号R有最小欧氏距离的码字。


Problems of ml decoding

Problems of MLDecoding

可能的码字个数:26*26=676

需计算这么多欧氏距离,计算量太大


Chase algorithm

Chase Algorithm

Hard Decided Sequence:

Reliability:

Step 1: find p least reliable positions.


Chase algorithm1

Chase Algorithm

Step 2:generate test patterns:

Step 3: decode the test patterns and form the code set C

Step 4: find the minimum distance code D.


Log likelyhood

Log likelyhood


Max logmap

Max-logMAP


Soft output

Soft Output

Computing the soft output corresponding to the jth bit:

In the decoded set C, if we can find a code word that complements with D at the jth bit position and has minimum distance with R


Soft output1

Soft output

  • If we can not find such a word in C,


Extrinsic information

Extrinsic information


Iterative decoding

Iterative decoding

Column --- row --- column ----- row ----- column …..


Performance

Performance


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