Adaptive Sliding Window Minimum Mean Square Error Inter-Carrier Interference Cancellation

Channel variation causes a loss of orthogonality among the subcarriers of an Orthogonal Frequency Division Multiplexing (OFDM) symbol and leads to inter- carrier interference (ICI) and degradation in performance. In this work, we propose a minimum mean square error ICI canceller with an adaptive sliding window (MMSE-ASW). In a frequency selective channel, the proposed MMSE-ASW adopts a different window size depending on the degree of ICI to which each subcarrier is subjected relative to the power of the signal part. A metric is computed for each subcarrier to determine the degree of interference which depends on the estimated ICI coefficients. A closed form is derived to get the optimum value of the window size used in the MMSE-ASW approach. We analyze the performance and the complexity trade-off of the algorithm. We demonstrate the effectiveness of the proposed method for a frequency selective fast fading channel, in a first generation digital video broadcasting system (DVB-T). As a result, we found that at a Doppler frequency of 100Hz, the proposed algorithm requires only about 32% of the complexity needed in the conventional MMSE approach to deliver the same bit error rate (BER) performance.