A Beamspace-based Pre-FFT Beam-forming Algorithm for OFDM Systems with Antenna Array

In this paper, a beamspace-based pre-FFT beam-forming algorithm is proposed for orthogonal frequency division multiplexing (OFDM) systems with antenna arrays in multi-path fading channels. In the receiver, multiple beams are generated firstly to cover the direction of arrival (DOA) range from 0 to 360 degrees. Then one or more delayed paths with large power are estimated by correlation process and two adjacent beams are selected for each path. Thirdly, those paths are extracted respectively from the two adjacent beams by adaptive algorithm and combined together before pre-FFT process. Computer simulation results show that the proposed algorithm has better performance than conventional MMSE based pre-FFT adaptive beam-forming algorithm, such as sample matrix inversion (SMI), etc, in multi-path fading channels.