What is Bluetooth?

Bluetooth, invented by Telecom Vendor Ericsson in 1994, is a wireless technology standard for short distance data exchanging building, using short-wavelength UHF radio waves in an ISM band from 2.4 to 2.485 GHz from fixed and mobile devices as well as personal area networks (PANs). It acts like an RS-232 data cable, with the exception being that it is a wireless technology.

All Bluetooth is managed by The Bluetooth Special Interest Group (SIG), a group of more than 30,000 different companies active in telecommunication, computing, networking and consumer electronics industries. The IEEE originally standardized Bluetooth as IEEE 802.15.1, but no longer maintains that standard. SIG is responsible for the supervision of specification development, management of the qualification program, and protection of the trademarks. The Bluetooth SIG standard should be kept to by all Bluetooth manufacturers.

A network of patents apply to the technology, which are licensed to individual qualifying devices.

Implementation

Bluetooth has a frequency range from 2402 to 2480 MHz, or from 2400 to 2483.5 MHz. There are also bottom end guard bands that are 2MHz wide, and top guard bands that are 3.5MHz wide.

Frequency-hopping spread spectrum technology used by Bluetooth. When using Bluetooth, the transmitted data goes through a series of steps. First, it will be divided into packets, and then each packet is transmitted to one of 79 designated Bluetooth channels that have a bandwidth of 1MHz. This is usually done at 800 hops per second, with Adaptive Frequency Hopping (AFH) enabled. Bluetooth low energy uses 2 MHz spacing, which accommodates 40 different channels.

Communication and connection

Although not all Bluetooth devices can achieve the highest level of communication, a master BR/EDR Bluetooth device can communicate with a maximum of seven devices in a piconet (an ad-hoc computer network using Bluetooth technology). The devices can switch roles, by agreement, the slave can become the master as well (for example, a headset initiating a connection to a phone necessarily begins as master—as initiator of the connection—but may subsequently operate as slave).

By connecting to the Bluetooth Core Specification, a scatter net will be established. Within this scatter net, different devices will simultaneously play the master role in one piconet, and the slave role in another.

At any given time, data can be transferred between the master and one other device (except for the little-used broadcast mode.) Certain slave devices are chosen by the master; typically, it switches rapidly from one device to another in a round-robin fashion. Because that master chooses which slave to address, being a master is a lighter burden while a slave is (in theory) supposed to listen in each receive slot. Both being a master of seven slaves and being a slave of more than one master are possible. The specification is vague as to required behavior in scatter nets.

Uses

Bluetooth is a wireless communication technology. It is primarily designed for low-power consumption, with a short range based on low-cost transceiver microchips in each device.

Bluetooth vs. Wi-Fi (IEEE 802.11)

There are similar applications for both Bluetooth and Wi-Fi (the brand name for products using IEEE 802.11 standards): setting up networks, printing, or transferring files. However, Wi-Fi is intended as a replacement for high-speed cabling for general local area network access in work areas or home, an application called wireless local area networks (WLAN). While Bluetooth was intended to be used for portable equipment and wireless personal area networks (WPAN), Bluetooth is a replacement for cabling in a variety of personally carried applications in any setting, and in fixed location application such as smart energy functionality in the home (such as thermostats).

Wi-Fi and Bluetooth are to some extent complementary in their applications and usage, though they both have their own advantages. For example, Wi-Fi is usually access point-centered, with an asymmetrical client-server connection with all traffic routed through the access point, while Bluetooth is usually symmetrical, between two Bluetooth devices. Bluetooth also features an outstanding performance in simple applications where two devices need to connect with minimal configuration- such as a button press in headsets and remote controls, whereas Wi-Fi performs better in applications where some degree of client configuration is possible and high speeds are required, especially for network access through an access node. However, Bluetooth access points do exist. Although ad-hoc connections with Wi-Fi are not as simple as with Bluetooth, they are possible. Wi-Fi Direct can add a more Bluetooth-like ad-hoc functionality to Wi-Fi.

Specifications and features The specifications were formalized by the Bluetooth Special Interest Group (SIG).
There are mainly four kinds of specifications produced by Bluetooth Core Specification Working Group (CSWG):
The Bluetooth Core Specification, release cycle is typically a few years in between;
Core Specification Addendum (CSA), release cycle can be as tight as a few times per year;
Core Specification Supplements (CSS), can be released very quickly;
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