Tight upper bound on the bit error probability of convolutionally encoded spread spectrum communication over frequency-selective Rayleigh-fading channels

A tight upper bound on the bit error probability of convolutionally encoded spread spectrum communication over frequency-selective Rayleigh-fading channels is derived. It is shown that combining coding and multipath propagation leads to a multiplication of time and multipath diversity. The main difference between the two types of diversity is that in contrast to time diversity the multipath diversity is achieved by splitting the total transmitted power. This fact has fundamental consequences to the effects of both types of diversity on the performance of coded spread spectrum systems. Finally, the results are used to predict the performance of CDMA systems