A Combined Time –Frequency Domain for Minimum Bit Error Rate Beamforming

Abstract

Modern mobile communication systems are increasingly moving towards higher bit rates, thus requiring more efficient use of the available bandwidth. Multi-path fading, co-channel interference (CCI) and inter-symbol interference (ISI) are the main problems affecting mobile communications and limiting their capacity and performance. To overcome such problems, Orthogonal Frequency Division Multiplexing (OFDM), and Adaptive Antenna Array (AAA) are used to increase the overall performance. In this paper, to overcome the problems mentioned before and to improve the communication system’s performance we used two main methods Pre-FFT and Post-FFT with OFDM. In our case, to obtain the optimal weight sets two algorithms the least mean square (LMS) and Minimum Bit Error Rate (MBER) were used with each method. The results obtained after analysis and simulation show that the binary phase shift keying (BPSK) signaling based on MBER technique utilize the use of the antenna array elements efficiently compared to the (LMS) technique in both cases of pre-FFT and post-FFT. In addition, we proposed a combined scheme that uses analysis in the time and the frequency domains based on MBER algorithm. The combined scheme provided better performance compared to each individual scheme with a slight increase in complexity which makes it suitable for practical systems.