By Steven Totolo and Franca Piccin

 The Scenario

 It's Sunday night. You just completed work on a company report to be discussed with your team at a meeting the next day out of town. Phew! You now try to link to the corporate Intranet site to upload your file. For some reason, however, your link to the site is not working. Should this be a major cause for concern? Under normal circumstances, yes. But surprisingly, you're not worried and trek off to bed. After a good night's rest, you arrive at work to pick-up messages. The laptop in your briefcase "spontaneously " connects to your office LAN and uploads the file that you could not send last night. As you look though the new messages and talk to your secretary, updated portions of the report from head office are being transferred to your laptop, unbeknownst to you. You collect your things and scurry off to the airport.

 Cruising at 10,000 feet, you open your laptop to check today's meeting itinerary and you realize that head office needs more information for the report. Clicking away you easily gather the information that's needed just as the plane arrives at your destination.

 You weren't the only one that had to make last minute changes. Other team members did too. But as all of you show up at the hotel meeting room, no one is complaining. Such is life in the frenzied corporate world! As you all come together, a "spontaneous" network is setup among the laptop computers and the various files worked on by each member are now being merged and assembled into a final report. Team members quickly grab a cup of coffee. By the time everyone takes a seat, each machine has an updated report with the latest information. The meeting starts with the team ready for action.

 The Solution

 Bluetooth makes this scenario possible. With Bluetooth radio technology designed into laptop computers, cellular telephones, printers, and desktop computers, there is no need for wires to interconnect these devices together to form a network. It allows for ad hoc, automatic, spontaneous, yet unseen, connections between devices.

 Ericsson Mobile Communications AB funded a study in 1994 under the code name "Bluetooth" named after Harald Blåtand , a 10th Century Scandinavian king who united his Danish kingdoms. Its scope was to find a means to provide mobile and business users with a method to integrate various products using a small short-range radio-based technology. This resulted in the creation of the Bluetooth protocol. In 1997 Nokia, IBM, Toshiba and Intel joined with Ericsson to create the Bluetooth Special Interest Group, SIG. The group has now grown to over 500 companies.

 Ericsson defined Bluetooth as a technology able to:

• handle voice and data information,
• work globally,
• establish ad-hoc connections,
• occupy a very small space in a product,
• use very little power,
• function as an open standard ,
• be affordable.

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The Technology

 Bluetooth uses the unrestricted 2.45 GHz ISM band, which is available globally with slight constraints in some locations relating to bandwidth and power output. Using a frequency hop transceiver with hops occurring at 1600 hops/sec, interference and fading effects are minimized since each packet is transmitted in a different hop frequency. A time-division duplex scheme is used for full-duplex transmission. Within the range of 10 cm to 10m, a gross data rate of 1 Mbits/s can be achieved to service mobile and business users. The range can be extended beyond 100m by increasing the transmit power. Second generation plans are to increase the data rate to 2 Mbits/s.

 Bluetooth can support an asynchronous data channel, up to three simultaneous synchronous voice channels, or a channel that simultaneously supports asynchronous data and synchronous voice. Each voice channel supports 64 kb/s synchronous (voice) link. The asynchronous channel can support an asymmetric link of 721 kb/s maximum in either direction while permitting 57.6 kb/s in the return direction, or a 432.6 kb/s symmetric link allowing for easy integration of TCP/IP for networking

 Collections of devices connected via Bluetooth technology in an ad-hoc fashion are called a piconet. Each unit can simultaneously communicate with up to seven other units per piconet. Although all devices are peer units, one acts as the master and the others as slaves for the duration of the connection to the piconet. The master unit provides the hopping sequence to synchronize all the devices in the piconet. Devices can be in one of several states: active, standby, hold, sniff and park.

 Initially, all devices are in the standby state, waking up every 1.28 seconds searching for a connection to a piconet through an inquiry or page access network command. The master unit can put slaves into the hold state to conserve power during quiet network periods. Slaves can also demand to be put into the hold state.

 

In the sniff state, a slave device listens to the piconet at a reduced rate, saving power. The park state is used to place a device in a reduced power state but it does not participate in the traffic while maintaining synchronization.

A scatternet is a collection of piconets operating independently and are not synchronized. This allows a large group of devices to network with each other by means of smaller sub nets. Since each piconet has the capacity of 1 Mbits/s between devices, scatternets allow the total throughput accumulated over all piconets to increase as more piconets are added. Testing has proven that the overall speed reduction of a scatternet consisting of 10 piconets is less than 10% due to collisions. This results in the potential total network throughput of approximately 9 Mbits/s.

 The Market

 HomeRF is also in the arena of wireless networking using the same 2.4 GHz frequency-hopping transmission scheme. However, Bluetooth promises to be easier to implement and less expensive.

 Dennis Moy, a strategic marketing manager at Hewlett-Packard Co., who is marketing director of the HomeRF consortium, acknowledged that Bluetooth chip sets will likely be less-expensive than HomeRF nodes - at least in their first incarnation.
"Bluetooth has always positioned itself as a point-to-point cable replacement," he said, "while HomeRF is meant to be an entire home network. That will obviously influence consumer perceptions of value."

 Version 1.0 of the specification is to be completed by the second quarter of 1999 with products available in the year 2000. The consortium is very excited about these future developments and eagerly is awaiting the advancement of Bluetooth.

 "This is the only real short-range wireless technology -- this is the one that has the most momentum and the most vendors behind it," says Andrew Seybold, an analyst of mobile computing technologies and publisher of Andrew Seybold's Outlook.

 Elsewhere, Silicon Wave hopes by the end of the year to bring out a transceiver which will integrate all receiver functions including a low noise amplifier and almost all the transmitter functions except the power amplifier.

With Bluetooth's potential to support home networking, David Lyon, president and chief executive officer of Silicon Wave said some may think of Bluetooth as a "Trojan horse into the home." Though not specified for compatibility with IEEE 802.11 for wireless LANs, Bluetooth will transmit TCP/IP. It can also scale upward to support RF data-transmission applications operating in the 5.X-GHz range. "Its initial appeal is that it needs no power, and costs almost nothing,"

 Notwithstanding, VLSI was first out of the gate with its implementation. "All the big groups are working on it but we are the first with a product in the market," Gerhard Heider, director of corporate product planning and development. A current three-block chip, with separate flash memory and radio module costs $20 a unit, but VLSI plans to put everything on a single chip at $5 per unit in 2001.

 This protocol and others are documented and updated regularly in the CABA Quarterly and in the CABA Standards Committee that meets quarterly to discuss issues that affect the business of members in the automation industry. The committee is open to all CABA members interested in up-to-date issues involving communications standards, wiring practices, and regulations.

Steven Totolo is president of tvcAutomation, a home automation specialist and a member of the CABA Standards Committee. He can be reached at (613) 795-7117; fax (613) 737-5323; email: sales@tvcAutomation.com