Block Turbo Decoder Design Hu Dongwei

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

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 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 Hard Decided Sequence: Reliability: Step 1: find p least reliable positions.

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

Max-logMAP

Soft Output 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 Computing the soft output corresponding to the jth bit:

Soft output If we can not find such a word in C,

Extrinsic information

Iterative decoding Column ---  row ---  column  row  column …..

Performance