A Novel Iterative Demodulation and Decoding Scheme with Convolutional Coding and Co-ordinate Interleaving

A novel iterative demodulation and decoding (ID) scheme is proposed for bit interleaved coded modulation (BICM) using co-ordinate interleaving (also known as signal space diversity (SSD)) and the rotation of a signal constellation in a fading channel. A soft-input soft-output demodulator is extended to incorporate SSD and iterative demodulation. It is shown that a well-considered choice of rotation angle for a specific signal constellation and labeling using SSD over a Rayleigh fading channel leads to a significant gain over conventional BICM-ID. Furthermore, the optimum rotation angle is found to be dependent upon the symbol labeling and the number of iterations performed between the decoder and the demodulator for convolutional codes.