An ECM-based receiver for OFDM signals affected by carrier frequency offsets
A receiver based on the expectation-conditional maximization (ECM) algorithm is presented to detect OFDM signals that are affected by carrier frequency offsets over time- varying multipath channels. The proposed scheme achieves joint channel estimation, frequency synchronization and data detection in an iterative fashion. Since the transmitted data at each iteration are recovered based on suitable channel and frequency estimates as obtained from the previous step, the new scheme is computationally efficient. It operates on a symbol-by-symbol basis for uncoded transmissions, whereas it can be implemented by modifying the branch metrics of a Viterbi decoder in case of trellis-coded modulations. Computer simulations confirm the effectiveness of the proposed receiver.