Developing a 3D Beam Former Model with Varied MIMO Channels

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) in conjunction with Multiple-Input Multiple-Output (MIMO) is considered as an attractive solution for future generation wireless networks with frequency selective fading environments. In this paper, a MIMO-OFDM based 3D Beamformer (3DBF) model has been developed using MIMO antenna arrays with both uniform and non-uniform planar array structures. The spatial mobility of the users and varied MIMO antenna structures have been considered for bringing the effect of different channel conditions with WINNER-II spatial channel model which considers 3D beamforming aspects. For the performance evaluation and comparison, linear adaptive channel equalization algorithms namely the Least Mean Square (LMS) and the Minimum Mean Square Error (MMSE) have been considered to be adaptively compensated the channel impairments caused by frequency selectivity in the propagation environment and under the condition of varied MIMO channel. The various units of the 3DBF system are described and implemented under MATLAB simulation environment. Extensive simulated studies have been carried out for Bit Error Rate (BER) and 3D beamforming performance evaluation with MMSE equalizer, the varied filter tap for LMS and MIMO antenna structures. BER reduction of 66.67% is obtained for LMS equalizer over MMSE equalizer at a fixed $\mathbf{SNR} =15 dB$ . The Mean Square Error (MSE) performance of the LMS equalizer at same SNR condition is improved than MMSE in proportion with the number of LMS filter tap and MIMO antenna structure which proves its superiority in the aspects of MIMO-OFDM based 3DBF system.