LDPC-based space-time coded OFDM systems performances over correlated fading channels

We consider, in this paper, a space-time coded (STC) orthogonal frequency-division mmultiplexing (OFDM) system with multiple transmitter and receiver antennas over correlated frequency- and time-selective fading channels. We propose a maximum-likelihood (ML) receiver for STBC-OFDM systems based on the expectation-maximization (EM) algorithm. We then propose a low-density parity-check (LDPC)-code-based STC-OFDM system to interface with the EM module. Using this encoder scheme together with the EM-based receiver, we built a novel turbo receiver which is particularly well suited for fast-time varying channels with a modest computational complexity.