A novel bandwidth efficient analog coding/decoding scheme for data transmission over fading channels

We propose a novel analog coding and decoding scheme for bandwidth efficient data transmission over a Rayleigh fading channel. A linear finite impulse response filter is used in place of the common convolutional encoder-mapper arrangement. With this filter the length of the orthogonal basepulse of the underlying digital modulation scheme is extended over many fading periods. This makes time diversity possible. On the other hand the flat fading now introduces linear time variant intersymbol interference. The attraction of this approach comes from the variety of suboptimal decoder structures, which are possible for signals with linear intersymbol interference. A suboptimal feed forward cascade decoder structure is derived. It is demonstrated by means of simulation results, that the proposed coder/decoder structure outperforms optimized trellis coded and PSK on the Rayleigh channel by 2.3 dB at P_e=10^-3, while achieving the same bandwidth efficiency. Both systems have comparable complexity. Our results seem among the best reported in the open literature for coded modulation with 2 information bits per transmit symbol