Downlink Power Control with Throughput and Rate Variation Guarantees

We consider the problem of providing guarantees on throughput and rate variation for interactive users in the downlink of CDMA systems, while minimizing the peak total transmit power, by using joint power and rate control. Under the assumption of independent and identically distributed channels, we derive that the optimal power allocation policy follows an increasing and leveling off pattern. We also develop an efficient method from the active set method, which is used in quadratic programming, to solve our problem. The computational complexity depends on the number of users and the number of joint channel states. Numerical results illustrate the sensitivity of the peak power to the required mean rate, the maximum allowed rate variation, and the number of users.