Bluetooth – an Enabler for Personal Area Networking

We find ourselves today often carrying numerous portable electronic devices, such as notebook computers, mobile phones, PDAs, digital cameras and mp3/MD/DVD players, used to help and entertain us in our professional life as well as in our private life. For the most part, these devices are used separately and their applications do not interact. Imagine, however, if they could interact directly and thus create a network where information may flow seamlessly between the devices – such a network of personal devices is often referred to as a personal area network (PAN). Moreover, access to the Internet via a (public) wireless LAN access point and/or via a 3G UMTS mobile phone would enable the PAN to be constantly on-line. The strongest candidate to provide with the cheap, short-range radio links necessary to enable such networks is the Bluetooth wireless technology. Seen from a networking perspective, a PAN will be expected to have participants, both of its “own” devices and “guest” devices from other PANs, continuously moving in and out of its coverage. To cope with this volatile nature of the network, the concept of adhoc networking may be applied to create a robust and flexible connectivity. A major technical step is taken when the Bluetooth piconet network architecture, a strict star topology, is extended into a scatternet architecture, where piconets are interconnected. A consequence of creating scatternet based PANs is that some nodes will form gateways between piconets and these gateways must be capable of time sharing their presence in each piconet they are members of. While the Bluetooth standard defines the gateway nodes, the actual mechanisms and algorithms that accomplish the inter-piconet scheduling (IPS) is left rather open. Given the lack of research literature in the subject, an overall architecture for handling scheduling in a scatternet is presented in this paper. A family of feasible IPS algorithms, referred to as Rendezvous Point algorithms, is also introduced and discussed.