ISI mitigation and channel tracking in MIMO-OFDM systems

When the channel response is longer than the guard interval in OFDM systems, inter-symbol interference (ISI) and intercarrier interference (ICI) occurs and this may seriously affect the receiver performance. In this paper, we consider the ISI and ICI mitigation in MIMO-OFDM systems. We propose to use a decision feedback technique for ISI cancellation and a cyclic reconstruction technique for ICI removal. Combining with the V-BLAST method, we obtain an iterative signal detection algorithm for MIMO-OFDM systems. Since the channel may be time-variant, we then further propose an adaptive time-domain channel tracking method. The algorithm can be implemented with IFFT so that its computational complexity is low. Simulations demonstrate that the proposed method can effectively enhance the overall MIMO-OFDM system performance.