Truncated Power Control in Code Division Multiple Access Communications

Code Division Multiple Access Communications Sang Wu Kim1 and Andrea Goldsmith Dept. of Electrical Engineering California Institute of Technology Pasadena, CA 91125 Abstract We analyze the performance of the truncated power control scheme in code division multiple access communication systems, which compensates for fading above a certain cuto fade depth. We investigate the power gain as well as the capacity gain over the conventional power control scheme as a function of the outage probability, in frequency selective Rayleigh faded and log-normal shadowed channels. It is found that the truncated power control scheme is more e ective for channels with a larger channel uctuation, and the capacity reduction due to the channel estimation error is on the order of e (M+1) e2b2=2, where b = ln 10=10, when the channel estimation error follows a log-normal distribution with standard deviation e, and the number of paths combined is M .