Automatic control on transmission power in wireless networking

The automatic control theory plays an important role in modern industries. With the rapid development of the Internet and a variety of wireless networks, its application field has been becoming wider and wider. However, in the design of networking protocols, instead of utilizing the classical control theory, most software engineers favor open-loop control. In reality, closed-loop control may well serve as a simple and efficient part in some cases. In this paper, we try to apply the classical control theory to the adjustment on the transmission power in wireless networking. As a result, we propose APC (Automatic Power Control), a distributed power control algorithm that can be used in conjunction with any routing protocols as long as the routing table of each node provides enough knowledge of local network topology. The basic idea of APC is to adjust the transmission power for each wireless node through an improved version of the classical PID (Proportion-Integral-Differential) control. The network topology derived under APC is also fed back to the routing table that is used as its input. Both theoretical analysis and simulation study show that APC is an effective application of the classical control theory in wireless networking.