Outage optimal node placement in ultra-wideband sensor networks

Ultra-wideband (UWB) wireless technology provides a suitable platform for a variety of sensing applications, since it possesses many useful and unique properties, such as large available bandwidth, low power consumption, precise ranging capability, high signal penetration of UWB signals, etc. However, UWB also introduces new design challenges with regards to medium access control (MAC) in sensor networks, especially if the original benefits of UWB ought to be retained. In this paper, we consider UWB sensor networks with random MAC which does not require overhead for collision avoidance. We first show that in such a scenario node placement can play a critical role to the performance of the UWB sensor network. Then, we investigate the problem of node placement in UWB sensor networks for achieving the most reliable communication between UWB sensors and the sink. Specifically, the tradeoff between the node density and the sensor-to-sink communication reliability is analyzed, and the optimal node density for the most reliable link is obtained. We present simulation results which confirm the correctness of the analytical method and illustrate the trade-off between energy consumption and performance for different MAC schemes.