Fixed-point implementation of space-time-turbo coded modulation

The effect of finite word length representation on the performance of space-time turbo coded modulation is studied in this paper. Space-time turbo coding is designed to achieve the high capacity offered by multiple-input-multiple-output (MIMO) channels. The performance of a wireless communication system is often studied in the literature assuming the floating point arithmetic. The practical implementation of such a system, however, is usually carried out with finite word length accuracy. The performance of the fixed-point implemented decoder based on the symbol-by-symbol max-log-maximum a posteriori (MAP) algorithm is evaluated in a quasistatic fading channel in this paper. The numerical results show that the decoder works with the fixed-point implementation without significant degradation in the FER performance. Also adequate word length configurations are presented.