Power control for wireless data

With cellular phones mass-market consumer items, the next frontier is mobile multimedia communications. This situation raises the question of power control for information sources other than voice. To explore this issue, we use the concepts and mathematics of microeconomics and game theory. In this context, the quality of service of a telephone call is referred to as the "utility" and the distributed power control problem for a CDMA telephone is a "noncooperative game". The power control algorithm corresponds to a strategy that has a locally optimum operating point referred to as a "Nash equilibrium". The telephone power control algorithm is also "Pareto efficient" in the terminology of game theory. When we apply the same approach to power control in wireless data transmissions, we find that the corresponding strategy, while locally optimum, is not Pareto efficient. Relative to the telephone algorithm, there are other algorithms that produce higher utility for at least one terminal, without decreasing the utility for any other terminal. This paper presents one such algorithm. The algorithm includes a price function, proportional to the transmitter power. The price acts as a tax on the utility of a transmission. When terminals adjust their power levels to maximize the net utility (utility price), they arrive at lower power levels and higher utility than they achieve when they individually strive to maximize utility.