As ubiquitous as the Java programming language, Bluetooth is found almost anywhere there’s a need to link devices to the Internet. According to bluetooth.com, “it is built into billions of products on the market today and connects the Internet of Things (IoT).”
Genesis, Definition and Etymology
The “short-link” radio technology known as Bluetooth was developed incrementally between the years 1989 and 1997. First, Swedish physicians Nils Rydbeck and John Ullman patented two inventions for a handsfree headset in 1989 applicable to both wired and wireless mobile phones. From this inception Bluetooth technology was created in 1994 as a standardized, secure protocol for transmitting and receiving data via a 2.4 GHz wireless link. Named by Intel engineer Jim Kardach, he facilitated creation of the Bluetooth Special Interest Group (SIG) in 1997. This SIG, formed from Intel, Nokia, Ericsson, IBM and Toshiba, now has over 30,000 member companies from industry sectors including consumer electronics, telecommunication, networking and computers. The SIG’s stated goal was to “build this universal, very low-cost, private wireless cable,” according to Kardach, whose specialty is power architecture. He adds, “You have to design things to work efficiently, but more importantly, do nothing efficiently. Those are the two rules of power management.”
That’s the underlying idea behind Bluetooth: it’s ideal for low-power, low-cost, short range (generally up to 30 feet/10 meters) wireless transmissions between electronic devices. Initially conceived to be a wireless replacement for cables connecting headsets, phones, computers, notebooks, keyboards and mice, Bluetooth is found in billions of devices made each year. For a manufacturer to license a Bluetooth device and utilize its associated patents, the product must meet SIG specification standards.
Take a look at this video to Bluetooth basics from MoreWireLess:
“Bluetooth” comes from the historical novel The Long Ships by Frans G. Bengtsson and derives its Anglicized version from the Scandinavian sobriquet (Blåtand) of the 10th century king Harald Bluetooth. Just as Blåtand consolidated a kingdom from various disparate Danish tribes, the Bluetooth technology unites a number of communications protocols into one single standard. The logo is a ligature of two runes combining the king’s initials, Hagall 
and Bjarkan <
.
Application
Utilizing adaptive frequency-hopping spread (AFH) spectrum radio technology, Bluetooth functions between the frequencies of 2400 and 2483.5 MHZ including guard bands at both top and bottom of the spectrum. Data is divided into packets and sent on one of 79 designated channels, each with a bandwidth of 1 MHZ and typically hopping 800 times per second. Bluetooth Smart (see below), an even lower energy wireless PAN, supports 40 channels while using 2 MHZ spacing.
There are four power classes of Bluetooth RF, as seen in the table below:
| Class | Maximum Permitted Power | Typical Range | |
|---|---|---|---|
| 1 | 100 mW | 20 dBm | ~100 meters |
| 2 | 2.5 mW | 4 dBm | ~10 meters |
| 3 | 1 mW | 0 dBm | ~1 meter |
| 4 | 0.5 mW | -3 dBm | ~0.5 meter |
Source: morelesscompare.com
Bluetooth uses packet switching with synchronized payload envelopes (SPEs) and headers under a master-slave configuration. The piconet, a wireless ad hoc network (WANET) sharing the same wavelength with other devices, uses no routers and connects the master to up to seven slaves. Note once again that Bluetooth Smart operates slightly differently from legacy Bluetooth but still utilizes the same spectrum.
For those PCs that do not have Bluetooth radio embedded, a small USB dongle can be used for communication between devices. Bluetooth v.1.1, v2.0 and v2.0 + Enhanced Data Rate (EDR) works natively with Windows XP SP2; Vista RTM/SP1 and the wireless feature pack or Vista SP2 with Bluetooth v2.1 + EDR; Windows 7 with Bluetooth v2.1 + EDR and Extended Inquiry Response (EIR). Apple products with Mac OS X v10.2 or higher (released in 2002) are compatible with Bluetooth. Applications are also available for Linux
The most recent version of Bluetooth is v4.2, released 2 December 2014, which incorporates Bluetooth Smart technology. Bluetooth Smart (or low energy or LE) “is intended to provide considerably reduced power consumption and cost while maintaining a similar communication range.”
Image Source: Wikipedia
Bluetooth and Wi-Fi
Bluetooth and Wi-Fi (a brand established by the Institute of Electrical and Electrical Engineers aka IEEE and using 802.11xx standards) share similar attributes but Bluetooth was created expressly for portable applications. The differences can be capsulized between WLAN (Wi-Fi) and WPAN (Bluetooth). One significant distinction is that while Wi-Fi is generally access point-centered, Bluetooth is usually symmetrical between two devices. Wi-Fi lends itself better to configuration whereas Bluetooth’s simplicity has more ad hoc functionality. Their technologies and usage are considered complimentary.
Interference
One double-edged characteristic of Bluetooth is the radio frequency (RF) used to communicate between devices. Hence, no direct line-of sight is needed. However, should other nearby devices digitally transmit on the same 2.4 GHZ frequency, interference of signal and degradation of service may result. Typical conflicts occur between devices such as cordless telephones (even those on a 5 GHZ bandwidth), digital baby monitors, Direct Satellite Service (DSS), wireless speakers – even microwave ovens. The newest Bluetooth devices, equipped with AFH, identify channels already in use and hops to ones that are open, thereby minimizing frequency conflict.
Still, should frequency interference still occur, there are ways to improve digital transmission.
* Barriers between devices, even at close range, can reduce signal efficacy. Metal in particular can be a significant impediment to communication. So remove Bluetooth devices from or near metal desks. Other problematic obstacles include windows of bulletproof glass and walls built from concrete, plaster, brick and marble.
* Experiment with different router channels to find a channel(s) free from the ones your existing Bluetooth devices use.
* If experiencing static on Wi-Fi calls, move closer to the router. A stronger Wi-Fi signal will generally overcome lower powered Bluetooth frequencies.
* Avoid microwave ovens and fluorescent lighting. Remember that you may have replaced an old-school incandescent bulb with compact fluorescent light (CFL) lamps. Swap CFLs for LED lamps for even greater energy efficiency and no RF interference.
USB 3.0 has been shown to cause interference with Bluetooth devices because the noise produced by USB 3.0 cables, devices and ports overlap the same bandwidth used by Bluetooth. The remedy is to either further separate offending devices from each other or apply shielding to cables and/or a computer’s internal USB components.
Vulnerabilities
The National Institutes of Standards and Technologies (NIST) provides a security inventory with guidelines and suggestions for installing and maintaining secure Bluetooth piconets, headsets and smart card readers. Bluetooth can be compromised by:
* Denial-of-service attacks
* Man-in-the-middle attacks
* Eavesdropping
* Resource misappropriation
* Message modification
Bluejacking, bluesnarfing and bluebugging are all examples of misuse of Bluetooth technology. While bluejacking generally involves little more than a mischevious message (i.e., “You’ve been Bluejacked!”), bluesnarfing and bluebugging are more malicious. Bluesnarfing steals data from unsuspecting targeted devices while bluebugging compromises phone and laptop security by creating a backdoor attack.
Coda
Bluetooth cites an April 2016 survey by Lux Insights, claiming 92% of global consumers are “aware” of Bluetooth technology. Moreover, consumers on average each own nearly four Bluetooth enabled devices (an increase from 2.7 in 2012) and 62% of consumers “prefer” Bluetooth in their technology purchases. ABI Research forecasts that “over three billion Bluetooth enabled products will ship in 2016.”
As manufacturers and consumers find greater applications and innovations for Bluetooth technology, the proliferation of Bluetooth devices appears to be an inevitable and integral part of IoT. No doubt the trends of growth and usage will continue to grow worldwide.