An Iterative Multiuser Receiver for Space-Time Coded MIMO-OFDM System

Orthogonal frequency division multiplexing (OFDM) is a popular technique to mitigate ISI caused by multipath fading effect of the radio channel. In practice, OFDM could be used in combination with space-time coding, which can be performed in a multiple-input multiple-output (MIMO) system, to increase the diversity gain and/or to enhance the system capacity over timevariant and frequency-selective channels. Otherwise, the performance wireless communications is also primarily limited by multiple-access interference (MAI) in multiuser applications. In this paper, an iterative receiver structure for space-time block coded MIMO OFDM scheme is exploited with error control coding technique. We implement multi-user environment and utilize an iterative method of equlization on receiver based on minimum mean square error (MMSE) multiuser detection followed by soft-input-soft-output (SISO) convolutional decoding. The frequency domain symbols are estimated in iterative process by updating extrinsic information in terms of log-likelihood ratios (LLRs).