Optimum power allocation for soft handoff algorithms over lognormal shadowing channels

Soft handoff uses macroscopic diversity to improve the performance of wireless communication systems. In this context, this paper shows that the diversity link statistics can be exploited to optimally allocate the power available for the uplink of soft handoff schemes operating over correlated lognormal shadowing channels. The performance criterion used in optimizing the power allocation is the outage probability which is the probability that the link quality falls below an acceptable level. As an illustration of the mathematical formalism some numerical examples for particular cases of interests are plotted and discussed. These results show that the performance gain provided by these power optimized soft handoff systems increases as the diversity order and/or the correlation coefficient between diversity links increases.