Systematic comparison of performance of different Adaptive beam forming Algorithms for Smart Antenna systems

Abstract

Smart antenna is the most efficient leading innovation for maximum capacity and improved quality and coverage. Efficient utilization of limited radio frequency spectrum is only possible to use smart/adaptive antenna system. Smart antenna radiates not only narrow beam towards desired users exploiting signal processing capability but also places null towards interferers, thus optimizing the signal quality and enhancing capacity. Smart antennas exploit space diversity to help provide high data rates, increased channel capacity, and improved quality of service. A systematic comparison of the performance of different Adaptive Algorithms for beam forming for Smart Antenna System has been extensively studied in this research work. Simulation results revealed that training sequence algorithms like Recursive Least Squares (RLS) and Least Mean Squares (LMS) are best for beam forming (to form main lobes) towards desired user but they have limitations towards interference rejection. While Constant Modulus Algorithm (CMA) has satisfactory response towards beam forming and it gives better outcome for interference rejection, but Bit Error Rate (BER) is maximum in case of single antenna element in CMA. The effect of changing step size for LMS algorithm has also been studied. Index Terms: Adaptive antenna systems, Constant modulus algorithm, Least mean squares, Smart antenna.