Adaptive Minimum Bit Error Rate Beamforming Assisted QPSK for Pre-FFT OFDM Communication Systems

Abstract A novel adaptive beamforming technique is proposed for broadband wireless communication with quadrature phase shift keying (QPSK) signaling based on MBER criterion, the adaptive antenna array (AAA) is combined with orthogonal frequency division multiplexing (OFDM) to combat the inter-symbol interference (ISI) and the directional interferences. One of the two main techniques which are used in OFDM systems is called Pre-FFT, where an optimum beamformer weight set is obtained in time domain before Fast Fourier Transform (Pre-FFT). In this paper, the optimum weight set and is obtained based on minimum bit error rate (MBER) criteria in pilot-assisted OFDM systems under multipath fading channel. Here, the development of the block-data adaptive to implementation of the MBR beamforming solution is based on the Parzen window estimate of probability density function (pdf). The simulation results show that the quadrature phase shift keying signaling based on MBER technique utilizes the antenna array elements more intelligently than the standard minimum mean square error (MMSE) technique. The MBER technique can be used to achieve excellent performance since it directly minimizes the BER and requires shorter training symbols. Index TermsMBER beamforming, OFDM systems, Pre-FFT, MMSE beamforming, probability density function (pdf), smart antenna. I