Accurate capacity analysis for MIMO-OFDM systems considering correlation between subcarriers

In previous study, the capacity of MIMO-OFDM systems were investigated by supposing that different MIMO subcarrier channels are uncorrelated. It is proven that different MIMO subcarrier channels are correlated even though different MIMO delay spread channels are uncorrelated (see (12)). Hence the previous capacity results shouldn´t express accurately the actual capacity. Based on the proposed hybrid-domain system model, we use the channel impulse response (CIR) matrix instead of the channel frequency response (CFR) matrix sequence to derive the capacity in this paper. Therefore, the correlation between subcarriers is involved in the proposed algorithms. Simulation results show that the capacity calculated by our algorithm is greater than the capacity calculated by previous algorithm, whether the channel state information (CSI) is known at the transmitter or not known at the transmitter.