Bluetooth (IEEE 802.15.1) is the most predominant of communication systems in portable devices. It is typically used for Personal-Area-Networks (PAN) or Piconets and communicates using FH-CDMA (Frequency Hopping Code Division Multiple Access) an ad-hoc paradigm also sometimes referred to as FHSS (Frequency Hopping Spread Spectrum) , , .
Bluetooth uses one of the ISM (Industrial, Scientific and Medical – ISM category) radio bands (2400-2483.5 MHz) specified by the International Telecommunication Union’s Radio communication sector (ITU-R). These bands are dedicated for use by one of the three ISM categories and are not subject to licensing .
Within this frequency band, the devices use 79 different 1 MHz channels in their hopping sequence which is pseudo-randomly generated. Each hop from channel to channel occurs 1,600 times per second for voice and data transmission and 3,200 times per second for page and enquiry scanning . To avoid collisions or cross channel interception the streams are coded (Code Division Multiple Access – CDMA) from each other so if two different communications are occupying the same frequency the transmissions are ignored if they do not suit the pre-agreed code for the appropriate data stream , , .
The latest in Bluetooth technology is version 4.0 or Low Energy Bluetooth. It was first deployed in the Apple iPhone 4S which was released late in 2011. Low Energy Bluetooth uses between 1 and 50 per cent of the power of classic Bluetooth devices allowing the communications platform to run for months or possibly years on small button batteries even with a range of 50 m which is 5 times that of classic Bluetooth class 2 radios . Although Bluetooth is capable of transmission via its own protocols since the development and release of Bluetooth 3.0 High Speed in 2009 greater speed is achieved by using a hybrid system using both Bluetooth and WiFi.
This article was created by --BRE. It was taken from The future of electricity in domestic buildings, a review, by Andrew Williams, published in November 2014.
 Related articles on Designing Buildings Wiki
- Glossary of electrical terms.
- ICT and Automation (ICTA) Scoping Study Report.
- Internet of things.
- Local area network.
- Smart buildings.
- Smart cities.
- Smart technology.
- The future of electricity in domestic buildings.
 External references
-  Karnik A and Kumar A. Performance analysis of the Bluetooth physical layer. 2000 IEEE International Conference on Personal Wireless Communications, Hyderbad, India, 2000.
-  Schilling D L. Frequency Hopping Code Division Multiple Access System and Method. USA Patent 5,459,759, 29 August 1994.
-  Haartsen J. BLUETOOTH—The universal radio interface for ad hoc, wireless connectivity. Ericsson Review - The Telecommunications Technology Journal, vol. 75, no. 3, pp. 110-117, 1998.
-  Padgette J and Scarfone K. Guide to Bluetooth Security (Draft). National Institute of Standards and Technology, Gaithersburg, Maryland, 2011.
-  Institute of Electrical and Electronics Engineering. Part 15.1: Wireless medium access control (MAC) and physical layer (PHY) specifications for wireless personal area networks (WPANs). IEEE Standards, 2005.
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