Low Complexity Interference Mitigation for OFDMA Uplink in Time and Frequency Selective Fading Channels

This paper investigated the intercarrier interference mitigation for the uplink of an orthogonal frequency division multiple access system in a time and frequency selective fading channel. The proposed algorithm squeezes the interference of subcarrier k into 2τ + 1 neighboring subcarriers by preprocessing the received signal and yields a banded structure interference matrix. Specifically, the value of τ mainly depends on the carrier frequency offsets and determines the squeezing depth which in turn influences the receiver implementation complexity. The proposed scheme exploits this banded structure and realizes a low complexity Minimum mean square error (MMSE) equalizer with iterative soft interference cancellation. Simulation results show that the bit error rate performance of our proposed algorithm approaches the existing full length MMSE equalizer at all signal-to-noise ratio regime with a significant reduction on computational complexity.