Joint Filtering Scheme to Suppress the Cochannel Interference in MIMO-OFDM Mobile Communication

This paper proposes a novel joint filtering technique in order to suppress the cochannel interference for multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) modulation systems. There are conventionally two techniques to suppress cochannel interference: 1) spatio-temporal filtering (STF) the received signals prior to the fast Fourier transform (FFT), termed preFFT-STF; 2) the spatial filtering (SF) the received signals posterior to FFT, termed postFFT-SF. With limited number of preamble symbols, preFFT-STF outperforms postFFT-SF due to the superiority in the parameter estimation accuracy. While with a large number of preamble symbols, preFFT-STF is poorer than postFFT-SF because it only has limited filtering capability. To achieve a suitable tradeoff between the filtering capability and parameter estimation accuracy, this paper proposes a novel joint filtering technique. The transmitted packet is firstly divided into two parts, and then the first part is detected by preFFT-STF while the second part is detected by postFFT-SF. Simulation results show that the proposed scheme outperforms significantly both the preFFT-STF and postFFT-SF systems.