CDMA dynamic downlink power control

Abstract

In current IS-95 systems, forward link power control is far less powerful than reverse link power control and in some cases, it results in the downlink capacity being more limited than the reverse link. This paper analyzes different algorithms and provides insight into the dynamics of downlink power control. An improved forward link power control approach based on the current one bit per frame feedback is suggested. This algorithm consists of three parts. First, the current mobile frame error rate is estimated based on the history of mobile feedbacks. The next two parts are linearization and a linear system controller. Simulation shows that, compared to a bang-bang control scheme, this algorithm can achieve the same frame error rate for a stationary channel with lower mean power. It also has good transient response for time varying channels. It can provide a good tradeoff between the steady state performance and dynamic response. Thus, the paper presents an algorithm to improve the current IS-95 forward link power control but in a more general sense, it presents a systematic approach to the designing of a power control unit.