Bluetooth: A viable technology for utility applications

Many factors have resulted in a new look at how technology is used within utility enterprises. One in particular holds tremendous potential to play a major role in the ongoing convergence of technology and business.

Bluetooth™ — a universal radio interface that allows electronic devices to communicate wirelessly via short-range ad-hoc radio connections — is emerging as a viable technology for business and commercial applications, despite its origins in the consumer electronics segment. A case in point is Norwood Systems’ EnterpriseMobility™ wireless office solution for voice data, currently in trial at Ernst & Young offices in the U.K.

A group of world-class manufacturers, including Ericsson, IBM, Intel, Microsoft, Motorola, Nokia and Toshiba, are leading the effort to create ubiquitous connectivity where any given device can connect to all other devices anywhere without explicit user interaction. This capability depends on embedded Bluetooth radios to create a link between computerised automation and telecommunications. The possibilities for commercial applications become mind boggling once Bluetooth is widely deployed. That day may not be far off, according to Cahners In-Stat Group, which projects the worldwide market to explode to 1.4 billion Bluetooth-enabled products by 2005.

Technical basics

Bluetooth technology provides wireless communications by means of short-range radio modules designed to operate at a frequency of 2.4 to 2.48 GHz — the worldwide unlicensed industrial, scientific and medical band. Initial specifications call for devices to transmit and receive at a range of 10 metres with raw data rates up to 1 Mb/s. The signal uses a spread spectrum, frequency hopping, full-duplex signal at up to 1,600 hops per second, creating time slots of 625 milliseconds in duration. Signal hops occur among 79 frequencies at 1 MHz intervals to give a high degree of security and interference immunity. An even higher level of security is attained through an inherent encryption process based on a key of up to 128 bits. 

The Bluetooth base-band protocol is a combination of circuit and packet switching. Time slots can be reserved for synchronous packets, and each packet is transmitted in  a different hop frequency. A packet nominally covers a single slot, but can be extended to up to five slots. Bluetooth can support an asynchronous data channel, up to three simultaneous synchronous voice channels, or a channel that supports asynchronous data and synchronous voice simultaneously. Each voice channel provides a 64-kb/s synchronous link. The asynchronous channel can support an asymmetric link with throughput of 721 kb/s in either direction while permitting 57.6 kb/s in the return direction, or a 432.6-kb/s symmetric link.

Always-on communications enable reliable data transfer

Bluetooth units are constantly listening for other Bluetooth units. When two or more come within range of each other, they can set up ad-hoc point-to-point or point-to-multipoint connections. Units can dynamically join or disconnect from the network. Two or more Bluetooth units sharing a communications channel form a piconet. The devices can establish up to 10 piconets to form ad-hoc scatternets, which allow data payloads to be passed from piconet to piconet.

In a scatternet, each piconet is identified by a different frequency-hopping sequence, with access to full bandwidth. All devices participating on the same piconet are synchronised to the same channel. To regulate traffic on each channel, one of the participating units becomes a master of the piconet, and all other units become slaves. Slaves can participate in different piconets, and a master of one piconet can be a slave in another. Each unit can assume only one role (master or slave) within each time slot. With the existing Bluetooth specification, up to seven slaves can communicate with one master. However, many Bluetooth units can be virtually attached to a master and can join the piconet instantly as needed.

This scheme of alternating channels (frequencies) and time slots provides an important feature for Bluetooth networks. Suppose a device in Piconet A needs to transfer data to a device in Piconet B. During the initial time slot the master in Piconet A directs data to a slave, Unit 4. Following clock synchronisation, which will take a portion of the next time slot, Unit 4 becomes the master in Piconet C and sends data to Unit 1 in Piconet B during the next full time slot. After resynchronising the clock back to Piconet B, Unit 1 reassumes the role of master and delivers the payload to its final destination, Unit 2, in the next full time slot.

The extended Bluetooth network

If the full potential of this technology is to be realised in the utility environment, a data network connecting the various Bluetooth devices to a utility’s information systems is required. The most expedient and inexpensive way to create this system is by use of the Internet. For metering applications, a Bluetooth module in every meter would collect usage data (or other information), then transfer the payload by scatternet to an access point (or aggregation point for data) connected to the Internet. Data could be pushed upstream to the utility on a scheduled basis (say every 5 minutes) or pulled by the utility on a demand basis. 

Several different capabilities should be integrated into the Bluetooth network to ensure reliable and secure operation. The IP-based network, which performs overall data management, should rely on a triad configuration for its associated switches. Route and carrier diversity is also needed to create a packet-switched network with essentially no down time. Of course, the utility must also use secure Internet connections to safeguard their data. 

A range of services

Once Bluetooth-enabled systems are deployed throughout the service territory, the utility has in effect built a wireless overlay network that enables a number of applications. For instance, the new data network can be used as a hub for two-way communications with remote equipment and field personnel. Potential applications include SCADA, automatic workforce dispatch, demand-side management and value added services. And because the Bluetooth network is modular and scalable, utilities can expand and mould it to meet specific operational requirements in the field.

With a Bluetooth-enabled network in place, utilities can also broadcast real-time rates, conduct on-demand meter reads, reduce peak load and incorporate functions such as distribution automation and remote connect/disconnect. Other service providers might also use the network for services that don’t require high data rates — security monitoring, appliance monitoring and emergency warning systems, to name several.

Compatibility issues 

A significant contributor to the technology’s adoption over the long term is the coexistence of Bluetooth with other wired and wireless technologies. Recent trials have demonstrated Bluetooth’s coexistence with wireless networks based on HomeRF and IEEE 802.11b standards. These results indicate that Bluetooth-enabled components will not interfere with new services delivered through a Bluetooth-enabled network. As a testament to compatibility, United Parcel Service has embarked on implementation of a new $100 million package sorting system that incorporates both Bluetooth and 802.11b data transfer. 

Conclusions

Although Bluetooth is not the only solution for the numerous applications industry innovators envision, it could be an important part of a total solution — or a value added service — for residences, offices and factories. The technology’s robust nature and flexibility merit serious consideration as a foundation for future business operations. Even more importantly, utility leaders should understand that deploying Bluetooth not only brings new, viable solutions to their own industry but almost ensures their participation in providing the broader ubiquitous network that customers want for always-on connections to anything, anytime, anywhere.