A Joint Channel and Frequency Offset Estimator for the Downlink of Coordinated MIMO-OFDM Systems

The issues of frequency offset and channel estimation are considered for the downlink of coordinated multiple-input multiple-output orthogonal frequency-division multiplexing systems. Multiple carrier frequency offsets exist in this coordinated system. Without implementing an appropriate compensation for these offsets, both inter-carrier and inter-cell interference will degrade the system performance. Here, we adopt a parallel interference cancelation strategy to iteratively mitigate inter-cell interference, and propose a frequency offset estimator, approximated by a Hadamard product and a Taylor series expansion, to eliminate the inter-carrier interference. Our scheme is significantly less complex than existing methods. Furthermore, the proposed channel estimator is robust to frequency offsets and performs comparably well to these conventional approaches.