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Impact of Imperfect Channel Estimation in HF OFDM-MIMO Communications

Multiple Input Multiple Output (MIMO) technology offers the possibility of increased throughput in wireless communications, and as such, it is a potential candidate for High Frequency (HF) systems where only small bandwidths are available. However, the increased wavelength and size of antenna elements complicate the implementation of HF multi-antenna transceivers. In this paper, we consider multi-carrier (OFDM) MIMO HF communication systems where the multiple non co-located antennas at each communication end are interconnected through Radio Frequency (RF) links. We consider Minimum-Mean-Squared-Error- (MMSE) pilot-assisted channel estimation at the receiver side in OFDM transmission, and, leveraging results from random matrix theory, we present novel upper and lower bounds on the achievable throughput in the presence of imperfect channel estimation. Our representative numerical results for a 9 × 9 HF MIMO system quantify the achievable rate for realistic HF channel parameters, validating the interest in multi-antenna systems.