Power control for cellular communications with channel uncertainties

In the reverse link of a wireless cellular network, power control is used to ensure that each link achieves its target signal-to-interference-plus-noise ratio (SINR), while minimizing the interference to adjacent cells. In cellular systems using direct-sequence code-division multiple access (CDMA), the SINR depends inversely on the power assigned to the other users in the system, creating a nonlinear control problem. Mobility of the terminals, along with associated random shadowing and multi-path fading, results in uncertainty in the channel state. A regulation controller is developed in this paper for a CDMA cellular system with uncertainties in the state and channel noise. The developed controller regulates the SINR to a small region about a target value. An analysis is also provided to examine how mobility and the desired SINR regulation range affects the choice of channel update times.