Effective power control in UWB systems using spreading code’s spatial resolution properties

Abstract

Power control is a very important issue for any mobile node on a network, because of its limited battery power. If nodes use Code Division Multiple Access (CDMA) to share the available bandwidth, the transmitted power needs to be well controlled, to avoid the rise of noise level on the network and interferences with other nodes. The problem is even more difficult in ad-hoc networks, because there is no base station to control each node's transmitted power. This work presents a cross layer approach between the physical and logical layers to solve the power control problem, in ad-hoc networks, using low power CDMA nodes for indoor propagation channels. Our work uses a code acquisition and tracking system on the physical layer to determine the Transmitter - Receiver (TR) distance. This information is provided to the upper layer. It is also proposed a design of a simple, collision free and power efficient MAC protocol named "distance aware power control" (DAPC), which defines an exclusion region around the receptor to overcome CDMA classical Multiple Access Interference (MAI) problems, like the "near-far" problem.