Design and simulation of a variable bit load adaptive OFDM transceiver for frequency selective channel

This paper presents the design and simulation of an adaptive LMS beamformer for OFDM receiver array in frequency selective channel. The adaptive array uses the least mean square (LMS) algorithm for beamforming, which minimizes the mean square error (MSE) between the received pilot signal and the reference one. The LMS system proofed to be very efficient in interference cancellation, steering toward the signal direction of arrival (DOA), and improving the signal to noise ratio (SNR). In addition an adaptive bit loading algorithm is also proposed in this paper which improves the overall throughput of the algorithm by assigning higher order modulation schemes to subcarriers with high SNR and more robust modulation schemes such as BPSK or DBPSK to subcarriers with low SNR. The performance of the suggested OFDM system is investigated and compared to the conventional OFDM system.