11 Oct Understanding Bluetooth Technology
Bluetooth is a wireless technology used to exchange data over short distances, from fixed mobile devices. This creates personal area networks (PANs) with high levels of security. The technology was created by telecom vendor Ericsson in 1994 and was originally planned to be a wireless alternative to RS-232 data cables. Bluetooth has the ability to connect several devices at a time which overcomes the problem of synchronization.
Bluetooth is managed by Bluetooth Special Interest Group, which is made up of more than 18,000 member companies covering the areas of telecommunication, computing, networking and consumer electronics. The special interest group oversees the development of the specification, manages the qualification program and protects the trademarks. A device needs to be qualified to standards defined by the group to be marketed as a Bluetooth device.
Bluetooth operates in the range of 2400-2483.5 MHz. This is in the globally unlicensed Industrial, Scientific and Medical (ISM) 2.4 GHz short-range radio frequency band. The radio technology used by Bluetooth is called frequency-hopping spread spectrum. The data that is transmitted is divided into packets and each packet is transmitted on one of the 79 designated Bluetooth channels. Each channel has a bandwidth of 1MHz and the first channel starts at 2402 MHz and continues up to 2480 MHz in 1MHz increments. Bluetooth performs 1600 “hops” per second, with Adaptive Frequency-Hopping (AFH) enabled.
A Bluetooth device can communicate with a maximum of seven devices in a piconet (a specialized computer network using Bluetooth technology), even though not all devices reach this maximum. The devices can switch roles, by agreement, and the secondary device can become the master device. For example, a headset that initiates a connection to a phone will begin as the master, since it initiated the connection, but it may subsequently decide to become the subordinate device.
The Bluetooth Core Specification provides for the connection of two or more piconets to form a scatternet, in which certain devices simultaneously play the master role in one piconet and the subordinate role in another.
Data can be transferred between the master and one other device at any given time. The master device chooses which subordinate to communicate with, it usually switches quickly from one device to another in a round-robin fashion.
There are several USB Bluetooth adapters or “dongles” available, some also include an IrDA adapter. Older Bluetooth dongles, have limited capabilities. They only offer the Bluetooth Enumerator and a less-powerful Bluetooth Radio incarnation. These devices are able to link computers with Bluetooth a distance of 100 meters, however, they do not offer as many services as the modern adapters do.
Bluetooth is a standard wire-replacement communications protocol primarily designed for low power consumption, with a short range based on low-cost transceiver microchips in each device. Since the devices use a radio communications system, they don’t need to be in visual line of sight of each other, however a quasi optical wireless path must be available.
Comparing Bluetooth to Wi-Fi
Bluetooth and Wi-Fi have some similar applications, including setting up networks, printing or transferring files. The difference is that Wi-Fi is intended as a replacement for cables for local area network access. Bluetooth is intended for portable equipment and its applications. Bluetooth is used to replace cables in several personally carried applications in any setting and also works for fixed location applications.
Wi-Fi is a wireless version of a wired Ethernet network, and requires configuration to set up shared resources, transmit files and to set up audio links. Wi-Fi uses the same radio frequencies as Bluetooth, but with higher power, resulting in higher bit rates and better range from the base station.
Bluetooth technology is used in many products, such as telephones, tablets, media players, and some high definition headsets, modems and watches. The technology is useful when transferring information between two or more devices that are near each other in low-bandwidth situations. Bluetooth is commonly used to transfer sound data with telephones or byte data with handheld computers.
Bluetooth uses confidentiality, authentication and key derivation with custom algorithms based on the SAFER+ block cipher. Bluetooth key generation is generally based on a Bluetooth PIN, which must be entered into both devices. This procedure might be modified if one of the devices has a fixed PIN. During pairing, a master key is generated, using E22 algorithm. The EO stream cipher is used for encrypting packets, granting confidentiality and is based on a shared cryptographic secret, which is a previously generated link key or master key.
There are many applications and uses for Bluetooth technology, many more are thought up everyday. So far, it has become the most successful means of connecting humans to computers for the reason of making information gathering and communicating easier.
For info on wireless infrastructures similar to Bluetooth, go to http://www.abr.com/Solution/Managed-Services.
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