Window Design for Non-Orthogonal Interference Reduction in OFDM Receivers

Abstract

For conventional orthogonal frequency-division multiplexing (OFDM) systems, the guard interval is disregarded in the receiver and rectangular shaped windows are used implicitly due to the discrete Fourier transform (DFT). We consider a Nyquist-shaped window in the receiver, so that the transmit signal does not need to be modified, and optimize the window shape in order to suppress interference from non-orthogonal single carrier interferer signals. For the window coefficients, a closed form solution is derived. This type of interference usually occurs in OFDM radio systems like Digital Radio Mondiale (DRM) that are operating in low frequency bands. (Disturbance is given for instance by harmonics of switched-mode power supplies.)

Cochannel interference cancellation for OFDM systems using joint detection based on the M-algorithm

“…For Figs. 8 and 9, additional results are shown for the optimized receive window [5], which achieves performance very close to the trapezoidal receive window for the considered scenario.…”

“…The receive signal for a single OFDM symbol 3 (time instant µ), disregarding intersymbol interference (ISI) components, is given by 5 ,…”

“…using the cyclic property of the receive signal and the Nyquist property of the receive window, we can write (9) as 4 For the OFDM symbol at time instant µ, the phase offset is given by 5 The summation limits of the DFT are relaxed for the application of windowing in Section 2.4 and are accounted by the windowing function w [k].…”