A cluster-based protocol for self-organizing UWB wireless ad hoc sensor networks

Ultra wideband (UWB) technology with features of low cost, low power and high time resolution has potentially important applications in wireless ad hoc sensor networks. This paper proposes a cluster-based protocol for a class of UWB wireless ad hoc sensor networks. We consider a network of a large number of virtually identical but stationary sensor nodes that are energy-constrained with limited computing capabilities. This protocol fully exploits the features of impulse-radio-based UWB technology and orthogonal signaling to allow sensor nodes self-organizing and becoming aware of their locations without the need to use ID numbers. The entire network is divided into clusters. Each cluster is uniquely identified by a gradient index and a sector index. Any detected information is transmitted via a multi-hop path characterized by steep descent in the gradient index. The proposed protocol combines the advantages of both flat-based and hierarchical-based routing protocols. In this protocol, the key issues of the physical layer and the medium access control tasks of the data link layer can be jointly handled by the appropriate use of multiple access techniques. Computer modeling demonstrates that the proposed protocol performs well with different network scenarios.