In this paper we analyzed the bit error rate performance of a switching algorithm between spatial multiplex-ing and diversity for an OFDM MIMO system with ideal channel state information. The effect of channel estimation error was studied and we verified by simulations that the spatial multiplexing outperforms the switching algorithm. Given that the switching algorithm is based on the comparison of the channel matrix Demmel condition number to a threshold, its accuracy is compromised when channel estimation error in-creases. As a first intuitive solution, we proceeded to the adaptation of the threshold, but this didn’t lead to a pertinent improvement for the main reason that channel estimation errors did affect the MIMO techniques which use different constellation. Based on that, we proposed a new estimation technique that improved the bit error rate performance significantly

This paper presents an extra processing added to conventional LS estimation to improve its performances in OFDM-MIMO systems. The new technique is based on the knowledge of the power delay profile. The application of the improved estimator is useful when employing advanced MIMO adaptation techniques such switching algorithms and leads to significant improvement in decision criterion precision and consequently in terms of BER.

Summary In this article, we propose a new criterion for a switching algorithm to be used in MIMO‐OFDM systems. The switching algorithm, which selects between spatial multiplexing and MIMO diversity using the Demmel condition number as selection metrics, is first analyzed. Then, we show the limitation of this criterion, when increasing the receive antenna number. As a solution, we propose multiantenna processing and SNR switching criterion as a novel selection metric. The channel between the transmitter and the receiver is assumed a Rayleigh‐fading channel. Simulations results show that the proposed switching algorithm improves the performances in terms of bit error rate (BER) for symmetric and asymmetric MIMO systems. The gain is about 3 dB at BER = 10−4 in (4×4) architecture and 2 dB at BER = 10−4 in (3×2) architecture.

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