A scatternet is a type of ad-hoc computer network

Computer network

A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....

 consisting of two or more piconet

Piconet

The original piconet was a networking type used on RM Nimbus computers.These days, a piconet' is an ad-hoc computer network linking a user group of devices using Bluetooth technology protocols to allow one master device to interconnect with up to seven active slave devices...

s. Both of the terms 'scatternet' and 'piconet' are typically applied to Bluetooth

Bluetooth

Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...

 wireless technology.

Description

A piconet is the type of connection that is formed between two or more Bluetooth-enabled devices such as modern cell phones or PDAs. Bluetooth enabled devices are "peer units" in that they are able to act as either master or slave. However, when a piconet is formed between two or more devices, one device takes the role of 'master', and all other devices assume a 'slave' role for synchronization reasons. Piconets have a 3-bit address space, which limits the maximum size of a piconet to 8 devices (2³ = 8), i.e. 1 master and 7 slaves.

A scatternet is a number of interconnected piconets that supports communication between more than 8 devices. Scatternets can be formed when a member of one piconet (either the master or one of the slaves) elects to participate as a slave in a second, separate piconet. The device participating in both piconets can relay data between members of both ad-hoc networks. However, the basic bluetooth protocol does not support this relaying - the host software of each device would need to manage it. Using this approach, it is possible to join together numerous piconets into a large scatternet, and to expand the physical size of the network beyond Bluetooth's limited range.

Currently there are very few actual implementations of scatternets due to limitations of Bluetooth and the MAC address

MAC address

A Media Access Control address is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used for numerous network technologies and most IEEE 802 network technologies, including Ethernet...

 protocol. However, there is a growing body of research being conducted with the goal of developing algorithms to efficiently form scatternets.

Future applications

Scatternets have the potential to bring the interconnectivity of the Internet to the physical world through wireless devices. A number of companies have attempted to launch social networking and dating services that leverage early scatternet implementations (see Bluedating

Bluedating

Wireless dating, Widating or Bluedating is a form of dating which makes use of mobile phone and Bluetooth technologies. Subscribers to the service enter details about themselves and about their ideal partner, as they would for other on-line dating services...

). Scatternets can also be used to enable ad-hoc communication and interaction between autonomous robots and other devices. sp soni

Research

Several papers exist that propose algorithms for scatternet formation, and many different approaches have been simulated in both academic and corporate R&D environments. Some early experiments with large Scatternets can be found at ETH Zurich

ETH Zurich

The Swiss Federal Institute of Technology Zurich or ETH Zürich is an engineering, science, technology, mathematics and management university in the City of Zurich, Switzerland....

 in the BTnode project

A student at University College Cork, Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 has recently developed a scatternet based application in the Java programming language, using the JSR-82 library. This applications main purpose is to facilitate parallel computations over Bluetooth

Bluetooth

Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...

 scatternets, using an MPI

MPI

-Science, information technology and engineering:* Magnetic particle imaging, an imaging technique still being developed* Magnetic-particle inspection, a non-destructive method used to detect defects in ferrous materials...

-style message passing paradigm. Although it only runs on the emulation environment provided by Sun's Wireless Toolkit

Sun Java Wireless Toolkit

The Sun Java Wireless Toolkit is a state-of-the-art toolbox for developing wireless applications that are based on JavaME's Connected Limited Device Configuration and Mobile Information Device Profile , and designed to run on cell phones, mainstream personal digital assistants, and other...

, it is capable of creating a scatternet of up to 15 devices and routing a message through the network.

In 2006, a student at the University of Technology, Iraq

University of Technology, Iraq

The University of Technology, Iraq is one of Iraq's largest universities. It is situated in the city of Baghdad, Iraq. The university is specialized in Engineering, Computer Sciences, and Applied Sciences and Technologies. It was founded in 1964.-History:...

developed an on-demand peer-to-peer
scatternet routing algorithm and protocol, with Java ME application based on JSR-82 library. This application was tested successfully on several real life Java-enabled mobile phones, and is capable of building large scatternets, but its only practical when routers are less than or equal
to 2 nodes.