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Receiver window design for narrowband interference suppression in IEEE 802.11a system

Orthogonal frequency division multiplexing (OFDM) has been adopted as the physical layer transmission technology in IEEE 802.11a standard, where the Fourier transform is used in demodulation. However, because of the effect of "spectral leakage" in discrete Fourier transform, narrowband interference is spread in the spectrum, thus, strongly impacts adjacent subchannels. Receive window function was proposed previously to suppress narrow band interference spreading in OFDM systems. We take the symmetry of the long preamble in IEEE 802.11a physical layer frame into account and propose a Hanning window based channel estimation. We also investigate the selection of window function for data reception based on the measurements of indoor wireless environment The joint windows-based receive scheme satisfies the 802.11a standard and requires no modification at the transmitter. Theoretical analysis and simulations demonstrate the effectiveness of this technique in improving the system performance.