Cancelling co-channel interference for MIMO-OFDM systems based on DCT and LDPC

The replacement of the traditional fast Fourier transformation (FFT) with discrete cosine transformation (DCT) in additive white Gaussian noise (AWGN) channel to set up MIMO-OFDM system is proposed in this article. Channel space multiplexing is realized by application of MIMO technology to OFDM system. With two antennas used in the base station and the mobile station respectively, each of the mobile stations within OFDM system can obtain two independent spatial channels. However, under normal circumstances, considerable fading, noise and interference in MIMO-OFDM channel result in co-channel interference, hence BER (bite error rate) performance drops under par. This article attempts to propose a solution to this problem by decoding spatial signal in an inverse channel matrix. Simulations accordingly carried out indicate that better BER performance can be achieved by adopting the solution proposed in this article, despite such influencing factors as the existence of MIMO channel. Last, it is proposed in this article to use low density parity-check code (LDPC) in the DCT based MIMO-OFDM system to cancel the co-channel interference further, which is known for its error correcting capacity, for coding and decoding. Simulation indicates that BER performance in a MIMO-OFDM-LDPC system exceeds that of existing MIMO-OFDM.