Adaptive antennas for OFDM

This paper explores the combination of adaptive antennas and Orthogonal Frequency Division Multiplexing (OFDM) for operation in a faded delay-spread channel. We consider the performance of the well-known Sample Matrix Inversion (SMI) algorithm for controlling an adaptive antenna in a pilot-symbol-assisted OFDM system. Several strategies are considered for deploying SMI with different levels of tracking capability over an OFDM time-frequency slot. We propose a modification to the SMI method which incorporates the concept of pilot-interpolation into the computation of the sample covariance matrix. This modified SMI algorithm is shown to provide performance superior to the other variations of SMI under consideration.