On the Uplink of a Cellular System with Imperfect Power Control and Multiple Services

We analyze the reverse link of a single wireless cell in which mobile phones simultaneously transmit to the base station using code division multiple access (CDMA). The mobiles are transmitting data which is delay intolerant, so that scheduling cannot be employed. There is a finite number of data classes, and the users transmit either data or a lower rate synchronizing signal. To overcome the near-far problem, received power control is used, which has a log-normal error. For each class there is an outage probability that the user's signal-to-noise ratio (SNR) will be met (when active and when idle). Refinements of the central limit theorem are used to determine the number of users of each class that can be supported, i.e., the capacity. The approximation can also be used to determine the minimal target powers necessary to meet the outage requirements. Comparison with simulation shows these approximations to be accurate.