Effective I/Q Imbalance Estimation Algorithm for MB-OFDM-Based UWB Systems in the Presence of Carrier Frequency Offset

This paper proposes a new I/Q imbalance estimation algorithm for multiband orthogonal frequency division multiplexing (MB-OFDM) based ultra-wideband (UWB) systems. The proposed algorithm is highly effective for the UWB channels with strong frequency selectivity in the presence of carrier frequency offset (CFO). In order to estimate I/Q imbalance, the 2nd-order moments of received signal are analyzed, and a metric function is derived considering CFO. The I/Q imbalance is estimated based on this function which can be sequentially calculated with only two preamble symbols per each sub-band in timedomain, which ensures immediate convergence and robustness to frequency selectivity. The performance of the algorithm is evaluated by simulations in the case of 480 Mbps transmission mode in WiMedia MB-OFDM system. The simulation results show that the proposed algorithm achieves about 4 dB SNR improvement over the existing methods at BER=10^-5 .