EXPERIMENTAL RESEARCH ON INTELLIGENT RECEIVING SYSTEM SUITABLE FOR HIGH-SPEED WIRELESS LOCAL AREA NETWORK

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Receiving systems suitable for multipath fading channels with co-channel interference were studied. First, we studied a receiving system equipped with both an M-sectored derectional antenna and an adaptive equalizer to mitigate the influence due to multipath propagation and co-channel interference. By using directional antennas, this receiving system can separate desirable signals from undesirable signals, such as multipath signal with longer delay time and co-channel interference. It accepts multipath signals which can be equalized by maximum likelihood sequence estimator (MLSE) , and rejects both multipath signals with longer delay time and co-channel interference. Based on computer simulation results, the proposed system was confirmed to have the capability of combating with a longer delayd signal and co-channel interference in Rayleigh-distributed multipath channels.Second, we implemented a new co-channel interference canceller to enhance the co-channel interference cancelling performance of the proposed receiver using DSP.It is based on MLSE and has superior BER performance compared with co-channel interference cancellers based on decision feedback equalizer, and its cancelling performance is improved by combining with trellis-coded modulation.Finally, we conducted laboratory experiments of the developed canceller, trellis-coded co-channel interference canceller (TCC), which utilizes both MLSE and trellis-coded modulation. It was shown that TCC significantly improved the bit error rate performance over a conventional co-channel interference canceller especially for Nakagami-Rice fading channels, typically encountered in a microcellular system, at the cost of a moderately increased computational complexity.