Multiple-access design for ad hoc UWB position-location networks

In this paper, we analyze the problem of medium access control (MAC) layer design for impulse-based ultra-wideband (UWB) position-location networks (PoLoNets). We focus our attention on PoLoNets in which stationary reference nodes are deployed in an ad hoc manner and determine their locations based on a small number of fixed anchors with known locations. Location and range information is propagated through the network of reference nodes in order to periodically estimate the locations of mobile nodes. The principal objective of our design is to minimize the localization error and convergence time of location estimates in the presence of node mobility and multipath. The properties of bounds on node localization accuracy in the presence range and location-estimation errors are derived. These results serve as a connection between the problem of multiple-access design and the accuracy of location estimates. A spread-spectrum based MAC protocol is developed that is shown to outperform the traditional carrier-sense multiple-access (CSMA) protocol in terms of accuracy and the convergence time of location-estimates