BEAM: a framework for bridge negotiation in Bluetooth scatternets

Bluetooth is a short-range wireless technology designed to connect various low power, resource constrained devices such as cameras, cell-phones, laptops, handhelds, etc. Devices form autonomous ad hoc networks of up to 8 active devices, referred to as piconets. Piconets may be inter-connected by one or more bridge devices to form a scatternet. The Bluetooth specification is very clear about piconet formation, maintenance, operation and termination, but only mentions the concept of a scatternet. The bridges are the most important part of the scatternet as they bear the responsibility of a switch -relaying traffic from one piconet to another. Generally, the implicit assumption made is that the bridge already exists or that the bridge can be formed in some manner. However, the issues surrounding the bridge are complex and involve the masters of more than one piconet. In this paper we propose a framework - the bridge establishment, adaptation and maintenance (BEAM) - for bridge formation, maintenance, negotiation and termination. We have enunciated the mechanisms by which a node may be made a bridge and how it may be used to add or replace subsequent bridges. The framework has been designed to be flexible so that, it may be used by any of the scatternet formation or performance improvement algorithms. It is a logical step absolutely necessary for real world Bluetooth scatternet working and is simply an enabling mechanism to be used in conjunction with other protocols. It is presented in the form of a design specification or a protocol that may be customized by different implementers, and yet maintain a very high degree of interoperability.