Reduced complexity MIMO turbo equalization for STTrC-codes

Turbo MIMO equalization in a space-time-trellis-coded (STTrC) system is considered in this paper. First, a low complexity MMSE equalizer is derived for decoding of STTrC-coded signals in frequency selective channels. The receiver is further modified so that only the significant portion of the channel impulse response is taken into consideration. The remaining (nonsignificant) portion of the channel impulse response is regarded as unknown co-channel interference (UCCI) and suppressed using the covariance estimation technique. Its performance is evaluated using measurement data obtained by the multidimensional channel sounder. The receiver performance is shown to be within 2 dB from the maximum-likelihood lower bound, which takes into account all multipath components.