The Future of Bluetooth: What It Can and Can't Do

[#1]

Bluetooth is a teenager! In its 13th year, the wireless protocol is, like other adolescents, expanding its horizons. Now it's grabbing new attention from office building architects, medical implant designers, and plenty of folks in between.

As was true also for Ethernet and the Rolling Stones, Bluetooth had sincere critics convinced it wouldn't matter past the year 2000. Not only has Bluetooth thrived, but it now does more than you might realize. Among Bluetooth-based products already in preparation or likely in coming years:

• Monitors for blood sugar or other medical variables. These Bluetooth devices continuously track and wirelessly report diagnostic information. Over 25 million diabetic Americans, for example, could soon be equipped to have their cellular handsets emit an alarm as the individual’s need for insulin approaches emergency levels.
• Wireless monitors and projectors. Prepare a presentation on a tablet computer. Then, as you walk up to a projector, the mobile device wirelessly provides a video feed to the projector and begins to share your creation with everyone in the room.
• Payment systems. Payment by means of mobile telephones (PDF link) is already exploding; Starbucks receives over 100,000 mobile payments most days now. The systems still can improve in security and convenience, especially for paperless travel boarding passes, and Bluetooth will probably be part of the answer.
• Clothing will communicate. Before long, your clothing may say, "'Want to go for a walk? You've been in that chair the last 110 minutes straight," or "OK: I can turn maroon for tonight."

Each of these innovations required several technical breakthroughs. While Bluetooth isn't always the flashiest individual component, its ability to make wireless connections rapidly and at low cost enables a wealth of impressive systems. Bluetooth is the digital equivalent of an eight-penny nail: familiar, easy to buy in volume, fits well in a variety of projects, and holds together the better-looking parts with few surprises.

The engineering basics

Let’s start with the facts that are probably already familiar: Bluetooth is a standard for wireless exchange of data. The standard is open—anyone can read and learn from IEEE 802.15.1, its official designation—but also proprietary, with licenses for patents and related rights currently available at no charge. The specification targets short-distance transmission in the 2.4-2.48 GHz industrial, scientific, and medical (ISM) radio band.

The standard includes enough security, synchronization, and related conveniences, at relatively low cost in materials, to encourage the label "personal area network" (PAN) for the result. PAN evokes an image of communications for you and your stuff, but not stuff that's on the other side of the room. A cordless earpiece that allows hands-free conversations through a cellular telephone is a common Bluetooth application; a wireless mouse or keyboard is another.

There are a lot of ways to transmit information from one place to another. Wireless communications comprises at least three distinct technologies whose capabilities overlap Bluetooth: Wi-Fi (wireless fidelity), NFC (near-field communications) and UWB (ultra-wideband radio, occasionally called "wireless USB").

Representative technology	Effective data rate, Mb/sec	Effective range, m	Maximum permitted power, mW	Spectrum
Bluetooth Class 1, Version 1.2	1	100	100	2.4-2.48
Bluetooth Class 1, Version 2.0	3	100	100	2.4-2.48
Bluetooth Class 3, Version 2.0	3	5	1	2.4-2.48
Bluetooth low energy Version 4.0	1	50	<2	2.4-2.48
Bluetooth high speed Version 4.0	480	10	1	2.4-2.48
802.11 WiFi	1-150	100-250	1-4000	2.4; 5.3-5.8
NFC	0.424	<0.2	2	0.3-100
UWB	3.1-650	10-700	1-75	0.3-100

In broad terms, Bluetooth emphasizes low power, simple set-up, and inexpensively mass-produced transceivers. UWB has high data rates. Wi-Fi generally wins on range. NFC is for almost-touching. The capabilities and even implementations of all four technologies are converging in many respects, though. Bluetooth Version 3.0 includes a specification for transmission that combines Bluetooth with Wi-Fi, for instance.

Also note that Bluetooth itself has a variety of aspects. Some of the literature talks in terms of "generations" of standards, and there are 29 specific "profiles," such as "fax" or "intercom," which define particular applications and the information they transact. The range of engineering involved in Bluetooth is so wide that it would be a full-time job to track it, let alone try to capture it all for a survey like the one you're reading.

Enthusiasm for Bluetooth Low Energy (LE) is high enough that the Bluetooth Special Interest Group (BT-SIG) "has begun referring to this technology as 'Bluetooth Smart' ...", according to Mario Pasquali, founder and chief architect of test and measurement company Ellisys SA. While LE is quantitatively "low energy," in that it operates with only a fraction of the power requirements of previous wireless standards, it's also qualitatively different: LE is so miserly with electricity that it is generally engineered as a permanent component running off its own built-in coin-cell battery.

Note that the ranges in the table above are often optimistic. A good connection within a noisy or dense building might demand being only a fraction of the distance away.

All of these targets are moving, moreover. Major Bluetooth players, for instance, have been researching higher-bandwidth transports with the potential to take Bluetooth to the Gb/s range.

For further comparison, consider a few representative wired technologies. HDMI 1.3 peaks at a data rate of 10.2 Gb/s, although plenty of HDMI equipment still runs at 1.485 Gb/s or lower. Ethernet 100Base-T is 100 Mb/s.

When will consumers see new Bluetooth devices?

Expansion of Bluetooth beyond its traditional applications in wireless headsets and keyboards has already begun. Both the iPhone 4S and RAZR XT912 employ LE, and manufacturers are rumored to be preparing a wide range of proximity detectors, wristwatch sensors, in-store advertising units, and other applications.

The Bluetooth Innovation World Cup (IWC) gives a useful peek at the possibilities. Both the breadth and practicality that hundreds of entrants demonstrate suggest that many new applications will come to market in the coming years. Pasquali expects "The future of Bluetooth will include more complex topologies and devices playing several roles at the same time." The newer Bluetooth specifications allow for multi-point and multi-mode connections. Complex audio systems in automobiles are likely to be an early showcase for these new Bluetooth capabilities. TV is another area Bluetooth will soon invade, Pasquali notes.

Health concerns

Will it make you sick to carry multiple radio transmitters on or even in your body? We certainly evolved in a radio-free environment for most of the last million years, so it's only reasonable to wonder about the impact of such a change.

On the other hand, Bluetooth has not yet been implicated by any scientific study, although plenty of searches have been conducted. In any case, Bluetooth operates with considerably less power than cellular handsets, so it's plausible to believe that Bluetooth radio waves are innocuous.

What it means for you

Comfortable with your wireless mouse or earbud already? Good: in the next few years, you'll probably run into more and more times when you want to use Bluetooth. Whether coordinating your rental car's sound system with your own gear, keeping on top of your medical vitals, or connecting your presentation to a wide-screen projector before you even realize one is available, Bluetooth will fit into more and more small but crucial niches of our lives.

Be on the look-out especially for chances to build in Bluetooth during construction or remodeling, and to stream data from existing devices to the cloud. While these two broad trends have only begun, they both represent opportunities to link IT strongholds to people and information that have usually been distant from IT.

Along with all these possibilities, which only require engineering the technology that's available now, a few gaps in Bluetooth definitions are likely to receive attention soon. While all sorts of commercial transactions involving point-of-sale payments and in-store proximity are possible now, their "best practices" haven't been fully worked out yet.

A particular puzzle that Pasquali classifies as a "typical 'chicken and egg' issue" is that "Bluetooth is almost non-existent in printing.” Bluetooth does have two printing profiles defined, but no mainstream devices use them. Apple's AirPrint is a proprietary solution. The old model of complex printer drivers installed on desktop computers was barely sustainable; in a world where consumers are carrying handhelds, cameras, cellular handsets, and a wealth of other mobile "content sources," it's past time for the printer manufacturers to pioneer connection methods that are quick and painless. Bluetooth is a natural candidate.

In all likelihood, Bluetooth's growth has only begun.

See also:

• Understanding Wireless Connectivity Options for Businesses
• The Future is…Bluetooth?
• Making Sense of the Radio Spectrum (infographic)

[#2]

"... occasionally called WUSB ..." is deeply misleading.  WUSB is an instance of UWB, but far from the only one.

Also, the article underemphasizes that radio engineering doesn't fit neatly in the table above.  Some standards have effective maximum characteristics (range, data-rate, and so on); others have trade-offs between different parameters; still others exhibit even more complexity.  Right now, it's hard for me to defend High Speed (4.0) as capable of 480 Mbps (although I can strain and do so); 300 Mbps is a more realistic limit.  Check with your RF professional, of course, before you start any exercise program.

I apologize for the error and confusion.