Multi carrier modulation for indoor wireless communications

This paper discusses Multi Carrier Modulation (MCM) with application to broadband Frequency Selective Fading (FSF) channels. The first part of the paper discusses the capacity of such channels subject to the assumption that the channel bandwidth is much larger than the coherence bandwidth. Under this condition, it is shown that for a given spectral efficiency, in terms of C/W (Bits/S/Hz), the FSF channel requires 2.5dB more power by comparison to the ideal AWGN channel in high Signal to Noise Ratio (SNR). The extra power requirement decreases to less than 2dB for SNR below 10dB. The second part of the paper discusses the performance of a differentially detected MCM system. It is shown that the average Bit Error Rate (BER) performance is at best similar to the performance achievable over flat Rayleigh fading channels if no channel coding is used. Block error rate results are also presented and used in predicting the average performance improvement due to linear block codes.