Improved Channel Estimation for Complexity-Reduced MIMO-OFDM Receiver by Estimation of Channel Impulse Response Length

Using a priori knowledge of maximum channel impulse response (CIR) length, time domain OFDM channel estimation systems outperforms frequency domain channel estimation. Because CIR length is an unknown quantity at the receiver side, a suitable estimation method is necessary. In this paper, we propose a novel algorithm named FCLI-Frequency Domain Channel Length Indicator, which estimates CIR length in order to minimize MSE. The FCLI algorithm works in OFDM systems with null-subcarriers, like the spectrum mask defined in IEEE802.11a/g and does not require to average indicators over more than one OFDM symbol. Furthermore, FCLI is designed to work in both SISO and MIMO-OFDM. The simulation results show that channel estimation performance by the FCLI algorithm can approach or outperform the performance with perfect knowledge of channel length in low or high SNR.