Networking / Beginners

Discovering Bluetooth Basics

Let's get the biggest question out of the way first: What the heck is up with that name? Well, it has nothing to do with what happens when you chew on your pen a bit too hard during a stressful meeting. Nor does it have anything to do with blueberry pie, blueberry toaster pastries, or any other blue food. Bluetooth - www.bluetooth.com is the Web site for the industry group - is named after Harald Blatand (Bluetooth). The idea here is that Bluetooth can unite things that were previously un-unitable.

The big cell phone (and other telecommunications equipment) manufacturer Ericsson was the first company to promote the technology (back in the 1990s, as we mention earlier), and other cell phone companies joined in with Ericsson to come up with an industry de facto standard for the technology. The Institute of Electrical and Electronics Engineers (IEEE) - the folks who created the 802.11 standards - have since become involved with the technology under the auspices of a committee named 802.15.

The initial IEEE standard for PANs, 802.15.1, was adapted from the Bluetooth specification and is fully compatible with Bluetooth 1.1, the most common variant of Bluetooth. (There are 1.2, 2.0 + EDR, and now 2.1 + EDR versions of the technology. They're compatible with Bluetooth 1.1 and add some additional features and performance.)

If you're looking for a few facts and figures about Bluetooth, you've come to the right tutorial. Here are some of the most important things to remember about Bluetooth:

  • Bluetooth operates in the 2.4 GHz frequency spectrum. It uses the same general chunk of the airwaves as do 802.11g and 802.11n. (This means that interference between the two technologies is indeed a possibility, though 802.11n draft 2.0 is designed to sense Bluetooth transmissions and switch to different channels so they don't interfere.)
  • The Bluetooth specification allows a maximum data connection speed of 723 Kbps. A few of the most recent Bluetooth specifications can go much faster (2.1 Mbps for Bluetooth 2.0 and 3.0 Mbps for Bluetooth 2.1, with a proposed Bluetooth 3.0 that can go up to 480 Mbps), but many Bluetooth devices still use the slower speed specification - and Bluetooth 3.0 won't exist for a few more years. Compare this with the 248 Mbps of 802.11n. Bluetooth is much slower than wireless LAN technologies for now.
  • Bluetooth uses much lower power levels than do wireless LAN technologies (802.11). Thus, Bluetooth devices have a much smaller effect, power-wise, than 802.11 devices. This is a huge deal for some of the small electronic devices because Bluetooth eats up a whole lot less battery life than 802.11 systems. The proposed Wibree specification of Bluetooth will use even less power than the current version; it's designed to be used in wireless-enabled watches and will increase the battery life of your cell phone Bluetooth headset five times what it is today.
    Remember Because Bluetooth uses a lower power level than 802.11, it can't beam its radio waves as far as 802.11 does. Thus, the range of Bluetooth is considerably less than that of a wireless LAN. Theoretically, you can get up to 100 meters (these are called Class 1 devices), but most Bluetooth systems use less than the maximum allowable power ratings, and you typically see ranges of 30 feet or less with most Bluetooth gear - which means that you can reach across the room (or into the next room), but not all the way across the house.
  • Bluetooth uses a peer-to-peer networking model. This means that you don't have to connect devices back through a central network hub like an access point (AP). Devices can connect directly to each other using Bluetooth's wireless link. The Bluetooth networking process is highly automated; Bluetooth devices actively seek out other Bluetooth devices to see whether they can connect and share information.
  • Bluetooth doesn't require line of sight between any connected devices. Bluetooth uses radio signals that can pass through walls, doors, furniture, and other objects. So you don't need to have a direct line of sight like you do with infrared systems.
  • Bluetooth can also connect multiple devices in a point-to-multipoint fashion. One master device (often a laptop computer or a PDA) can connect with as many as seven slave devices simultaneously in this manner. (Slave devices are usually things such as keyboards and printers.)

The really big deal you should take away from this list is that Bluetooth is designed to be a low-power (and low-priced!) technology for portable and mobile devices. Bluetooth isn't designed to replace a wireless LAN. It's designed to be cheaply built into devices to allow quick and easy connections.

Some of the PAN applications that Bluetooth has been designed to perform include:

  • Cable replacement: Peripheral devices that use cables today - keyboards, mice, cell phone headsets, and the like - can now cut that cord and use Bluetooth links instead.
  • Synchronization: Many people have important information (such as address books, phone number lists, and calendars) on multiple devices (such as PCs, PDAs, and cell phones), and keeping this information synchronized (up-to-date and identical on each device) can be a real pain. Bluetooth (when combined with synchronization software) allows these devices to wirelessly and automatically talk with each other and keep up-to-date.
  • Simple file sharing: If you've ever been at a meeting with a group of technology geeks (we go to these meetings all the time, but then, we're geeks ourselves), you may have noticed these folks pulling out their Windows Mobile and Palm PDAs and doing all sorts of contortions with them. What they're doing is exchanging files (usually electronic business cards) via the built-in infrared (IR) system found on Palms. This system is awkward because you need to have the Palms literally inches apart with the IR sensors lined up. Bluetooth, because it uses radio waves, has a much greater range, which doesn't require direct IR alignment - and is much faster to boot.

Look for even more cool applications in the future. For example, Bluetooth could be used to connect an electronic wallet (on your cell phone) to an electronic kiosk. For example, a soda machine could be Bluetooth enabled, and if you wanted a soda, you wouldn't need to spend ten minutes trying to feed your last, raggedy dollar bill into the machine. You would just press a button on your PDA or cell phone, and it would send a buck from your electronic wallet to the machine and dispense your soda.

Another common future application may be customized information for a particular area. Ever go to one of those huge conferences held in places like Las Vegas? The booth numbers tend to go from 0 to 20,000, and the convention floor is about the size of 50 football fields - in other words, it's difficult to find your way around. With Bluetooth, you can simply walk by an info kiosk and have a floor map and exhibitor display downloaded to your phone. We're hoping that this feature is in place next time we go to the Consumer Electronics Show; we hate being late for appointments because we're spending an hour searching for a booth.

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