Performance Analysis of Adaptive Beamforming Algorithms for Orthogonal Frequency Division Multiplexing System

Orthogonal Frequency Division Multiplexing (OFDM) is gaining popularity for high data rate communication systems. We propose the use of adaptive beamforming for interference rejection in OFDM systems, due to its advantages over equalization. An adaptive beamformer uses the concept of spatial filtering to direct the antenna beam towards the desired signal/transmitter and place a null towards the interfering signal. The Fast Fourier Transform (FFT) at the receiver end of an OFDM system enables the use of frequency domain beamforming to reduce narrow band interference individually across all the subcarriers. We implemented both decision directed and blind algorithms. Use of these algorithms reduced the Bit Error Rate (BER) to a great extent. The performance analysis for Least Mean Square (LMS) algorithm, Recursive Least Squares (RLS) and Constant Modulus Algorithm (CMA) for hundred OFDM symbols and five hundred and twelve subcarriers, four hundred and is provided.