Pre-FFT Adaptive Spatial Filter Applied to OFDM Systems

This paper proposes an adaptive spatial filter scheme in time-domain (pre-FFT), aimed to improve the performance and the capacity of OFDM systems. This strategy uses a supervised adaptive algorithm, with frequency domain multiplexed pilots of the OFDM system as reference. The simplicity of the proposed structure, as well as the method used to obtain reference signals for the adaptive spatial filter are important aspects that distinguish this paper from other publications. Another difference is the discrete characterization of the OFDM system, which resulted in a more appropriate model for the development of this proposal. Details on the operation of the proposed scheme, as well as the BER performance curves, are presented here. The proposal investigated here allows significant reduction in the guard interval of the OFDM system, thereby increasing its robustness or transmission capacity.