A fault-tolerant distributed formation protocol for Bluetooth scatternets

A Bluetooth scatternet is a network topology that is formed by inter-connecting piconets. A piconet is a starshaped ad-hoc networking unit that can accommodate eight Bluetooth devices, a master and up to seven slaves. By designating certain piconet nodes as bridges, or gateways, we can interconnect piconets by forcing the bridge nodes to interleave their participation in multiple piconets. Bridge nodes form an auxiliary relay connection between adjacent piconet masters and are fundamental for establishing scatternets. In this paper we present a new fault-tolerant approach to scatternet formation that is selfhealing and operates in a multi-hop environment. Our Bluetooth Distributed Scatternet Formation Protocol (BTDSP) establishes a flat scatternet topology, allows incremental node arrival, and automatically heals scatternet partitions by re-incorporating disconnected nodes. By maintaining neighbor associations in soft state, existing links can also be re-established quickly upon disconnection due to intermittent wireless connectivity. By only using slave/slave bridges, the algorithm is resilient to both node failure and wireless interference. It also prevents time-slot waste due to master/slave bridges being away from their piconets.