In Chapter 7 we introduced the WPAN infrastructure and Bluetooth, a technology that supports short range communications and home networking. Initially, Bluetooth's primary function was “cable replacement”, i.e., elimination of short-range wired-based communications. Therefore, most of the Bluetooth applications presented were based on point-to-point and point-to-multipoint wireless links. However, the applicability of Bluetooth has gradually extended, covering various aspects of office automation, industrial process automation, and even mobile ad-hoc networking. Many of these extensions include Mobile-to-Mobile (Mo2Mo) networking, beyond the traditional clustering within piconets. An essential condition of Bluetooth networking is its ability to work in extended ranges, up to 1 km, using omnidirectional antennas. Another condition is low power consumption while maintaining a high data rate. The Bluetooth networking architecture is shown in Figure 12.1.
Bluetooth networks consist of multiple piconets interconnected into larger scatternets, providing a community area network of multiple groups of users. A piconet consists of a single Master Station (MS) and several Bluetooth (B)-enabled devices. Sophisticated home networks can be organized as scatternets where each piconet represents an ad-hoc grouping of Bluetooth-enabled devices with common functionality such as environmental automation, audio/visual systems, and computing systems.
Within a piconet, the master station establishes connections with all the Bluetooth devices, including a smart cell phone that can provide connectivity to a mobile service provider and the Internet. Within scatternets, Bluetooth connections are established between master stations to allow multi-hop routing.