TABLE OF CONTENTS Power control is applied to systems where users interfere with each other. The goal of power control is to adjust the transmit powers of all users such that the SINR of each user meets a given threshold required for acceptable performance. This threshold may be different for different users, depending on their required performance. This problem is straightforward for the downlink, where users and interferers have the same channel gains, but is more complicated in the uplink, where the channel gains may be different. Seminal work on power control for cellular systems and ad hoc networks was done in [27; 28; 29], and power control for the uplink is a special case for which these results can be applied. In the uplink model, the kth transmitter has a fixed channel power gain g k to the receiver. The quality of each link is determined by the SINR at the intended receiver. In an uplink with K interfering users, we denote the SINR for the kth user as
where P k is the power of the kth transmitter, n is the receiver noise power, and ? is interference reduction due to signal processing. For example, in a CDMA uplink the interference power is reduced by the processing gain of the code, so ? ? 1 /G for G the processing gain, whereas in TDMA ? = 1 .
Each link is assumed to have a...
