dBBlue: low diameter and self-routing bluetooth scatternet

This paper addresses the problem of scatternet formation for single-hop Bluetooth based ad hoc networks, with minimal communication overhead. We adopt the well-known structure de Bruijn graph to form the backbone of Bluetooth scatternet, hereafter called dBBlue, such that every master node has at most seven slaves, every slave node is in at most two piconets, and no node assumes both master and slave roles. Our structure dBBlue also enjoys a nice routing property: the diameter of the graph is O(log n) and we can find a path with at most O(log n) hops for every pair of nodes without any routing table . Moreover, the congestion of every node is at most O(log n/n), assuming that a unit of total traffic demand is equally distributed among all pair of nodes. We discuss in detail a vigorous method to locally update the structure dBBlue using at most O(log n) communications when a node joins or leaves the network. In most cases, the cost of updating the scatternet is actually O(1) since a node can join or leave without affecting the remaining scatternet. The number of nodes affected when a node joins or leaves the network is always bounded from above by a constant. To facilitate self-routing and easy updating, we design a scalable MAC assigning mechanism for piconet, which guarantees the packet delivery during scatternet updating. The dBBlue scatternet can be constructed incrementally when the nodes join the network one by one. Previously no method can guarantee all these properties although some methods can achieve some of the properties.