Trellis-Based Joint Huffman and Convolutional Soft-Decision Priority-First Decoding

Let A = {a₁,a₂,..., a₂₆} be a set of 26 English alphabets with probabilities P = {p₁,p₂,... ,p₂₆} and C be the corresponding Huffman code that has 26 codewords {c₁,c₂,... ,c₂₆} with average codeword length 4.15573. The respective lengths of the codewords are given by {lscr₁,lscr₂,...,lscr₂₆}. According to P, a concatenation of 1000 symbols randomly generated from A is Huffman encoded into a bitstream x of length M and x is further encoded into a bitstream y of length N by a binary (2,1,6) convolutional code with octal generator sequence 554 and 744. Then, y is BPSK modulated and sent over an AWGN channel. Let r = (r₁, r₂,..., r_N) denote the received bitstream. This work assumes that no bits are deleted by the channel, and that the side information N is known at the receiver.