Optimal windowing in MIMO OFDM for network interference suppression

Abstract

The combined use of orthogonal frequency-division multiplexing (OFDM) and wireless multiple-input multiple-output (MIMO) links is becoming common. For many applications, such as ad hoc wireless networks, interference is a significant issue. MIMO links allow for the spatial mitigation of interference; however, spatial interference mitigation when using OFDM modulation performs somewhat poorly because of the relatively limited interference spectral confinement of the Discrete Fourier Transform. Traditional windowing approaches that minimize leakage of the interference into neighboring carriers induce intercarrier interference. In this paper, a technique is developed for determining optimal windows that trade off interference suppression with intercarrier and interframe interference. This technique assumes channel statistics are known. Optimized windows for various levels of interference, delay spreads, frame length, and cyclic prefix lengths can be produced.