Decision feedback IBI mitigation in OFDM systems

Abstract

When the channel response is longer than the guard interval in OFDM systems, inter-block interference (1131) will occur and the desired circular convolution property (the transmit symbol and the channel response) will not hold. These problems can seriously degrade the performance of OFDM systems. In this paper, we combine the decision feedback and cyclic reconstruction techniques with an iterated channel estimate method to remedy these problems. We consider pilot-tone based OFDM systems operating in fading channel environments. We derived a least-squares (LS) channel estimation and the optimal frequency domain equalizer (FEQ). Since the computational complexity of the optimal FEQ is high, we then use a simple suboptimal one. Incorporating with decision feedback and cyclic reconstruction, we obtain an iterated IBI mitigation method. Simulations based on a modified DVB-T specification demonstrate that the proposed method can effectively reduce the 1131 and enhance the overall system performance.