Multi-Stage Threshold Decoding for Self-Orthogonal Convolutional Codes

This paper describes a least complex high speed decoding method named multi stage threshold decoding (MTD DR) Each stage of MTD DR is formed by the traditional threshold decoder with a special shift register called difference register (DR) After flipping each information bit DR helps to shorten the Hamming and the Euclidian distance between a received word and the decoded codeword for hard and soft decoding respectively However the MTD DR with self orthogonal convolutional codes (SOCCs) type 1 in this paper makes an unavoidable error group which depends on the tap connection patterns in the encoder and limits the error performance This paper introduces a class of SOCCs type 2 which can breakdown that error group as a result MTD DR gives better error performance For a shorter code (code length = 4200) hard and soft decoding MTD DR achieves 4 7 dB and 6 5 dB coding gain over the additive white Gaussian noise (AWGN) channel at the bit error rate (BER) 10(-5) respectively In addition hard and soft decoding MTD DR for a longer code (code length = 80000) give 5 3 dB and 7 1 dB coding gain under the same condition respectively The hard and the soft decoding MTD DR experiences error flooring at high E-b/N-0 region For improving overall error performance of MTD DR this paper proposes parity check codes concatenation with soft decoding MTD DR as well