An iterative receiver for coded OFDM systems over time-varying wireless channels

Abstract—This paper presents a low-complexity iterative receiver for coded OFDM systems. We present an EM-based iterative algorithm for combined channel estimation and de-coding that makes collective use of the available data and system constraints. Minimum number of pilots are sent only in the first symbol of the packet to acquire the channel; then the iterative algorithm is used to track the channel time vari-ation, which is assumed to follow a state-space model, using an EM-based Kalman filter. Data recovery can be achieved within a single OFDM symbol. We also propose the use of an optional outer LDPC code in serial concatenation to of-fer a trade-off between latency and performance, especially for multi-amplitude modulations, without affecting the com-plexity of the core iterative algorithm