TDMA cellular soft output adaptive equalization based on the modified-MAP algorithm

The concatenation of an adaptive MLSE equalizer and a Viterbi decoder is a powerful means for improving the performance of mobile communication system receivers. The best system performance is obtained when the Viterbi algorithm is used with soft decisions. It is known that the original MAP algorithm provides optimal a posteriori probability or reliability information. However, the SOVA is typically used instead due to the implementation complexity of MAP. A new algorithm, called the modified-MAP algorithm, was developed to produce more accurate reliability information with reduced complexity. This paper proposes a new soft output equalizer based on the modified-MAP algorithm for TDMA systems over multipath Rayleigh fading channels.