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Wireless Wonders

Computer Engineers Improve Wireless Networks by Making Users Connect Through Each Other

July 2005

Several cities, including Philadelphia and San Francisco, are considering installing city-wide wireless internet connections of a new generation. These so-called wireless mesh networks will enable users to route their connections through other users' computers, in order to find available channels more efficiently and reduce down time.

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Science Insider

Science behind the news is funded by a generous grant from the NSF

HOW IT WORKS: Wireless, or "WiFi," technology and the Wireless Internet are a direct result of the staggering growth in cell phone use over the last decade. It is a system of connecting personal computers and other electronic devices in close physical proximity through high-frequency radio waves instead of wires or cables. The Wireless network is basically a series of linked transmitters and receivers. There are two main components in a traditional hub-and-spoke wireless network: wireless access points and wireless clients. Access points are base stations that are connected to the network at regular intervals to provide maximum coverage in a given region. Wireless clients are the network interfaces housed in computer devices that communicate with the access point.

Many factors can affect the speed of a wireless connection: how far you are from the access point, for example, or interference from other devices, such as cordless telephones. In general, the closer you are to an access point, the faster your connection will be; speeds fall back automatically as you move away to compensate for the distance. Also, since wireless users must share bandwidth, the more clients are connected to a specific access point, the slower the speed will be for each client.

MESH ADVANTAGES: Mesh network models are more decentralized than the hub-and-spoke approach currently used. Mesh networks promise several key advantages over traditional wireless technologies like cell phones or Wi-Fi. These include higher speeds, less radio interference, less network congestion, better geographic coverage, and tighter security. It's also cheaper to build a mesh network, since it can be set up using poles already in place for streetlights, traffic signals and road signs. Routers are simply bolted to the posts and plugged into the photocell power adapter already atop most streetlights. The routers are then automatically assimilated into the mesh network. If a cellphone tower stops working because of a power failure or terrorist attack, users will be cut off entirely from access in that cell. With a mesh network, any piece of mesh hardware -- a wireless router, for instance, or a laptop's interface card -- is fully assimilated into the network and can act as a relay. If one relay goes down, there are lots of alternate routes available.

The IEEE-USA contributed to the information contained in the TV portion of this report.

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