Performance of BPSK and TCM using the exponential multipath profile model for spread-spectrum indoor radio channels

A common approach to analyzing the performance of a spread-spectrum communication system in fading is to assume that the multipath profile is a constant function of delay. However, different multipath profile models can lead to significant differences in predicted system performance, so caution should be exercised when choosing a particular model for analysis. Several previous studies show that a good fit to the experimentally measured multipath profile of indoor wireless channels is an exponential function. Assuming Rayleigh fading and an exponential multipath profile, in this paper we derive a closed form expression for the bit error rate of biphase-shift-keying and an upper bound for trellis-code-modulation both with combined spread-spectrum and antenna diversity. Comparison of these results with simulated results based on actual indoor channel measurements shows that the exponential profile model differs from the simulation model by only 1-2 dB whereas the constant profile model differs by as much as 5 dB