Cochannel interference cancellation for OFDM systems using joint detection based on the M-algorithm

In this paper, orthogonal frequency-division multiplexing (OFDM) based wireless systems with cochannel interference are considered. Interference from transmitters in neighboring cells with synchronized symbol time is assumed. Due to differences in the carrier frequencies of desired user signal and interferer signal, each interferer subchannel signal is spread over many subcarriers of the receive signal (receiver synchronized on the desired user signal). Therefore, intercarrier interference (ICT) arises and common interference cancellation approaches based on prefiltering are unfavorable. We propose a detection approach, where the interferer signal is jointly detected with the desired user signal by a sequential decoding algorithm. Simulation results reveal large performance improvements for a binary phase-shift keying (BPSK) modulated 64-point discrete Fourier transform (DFT) OFDM signal with moderate-to-strong interference for realistic channels and ideal channel state information. By using additional windowing of the receive signal in time domain, further improvements may be achieved.