WiMAX

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IEEE 802.16 is working group number 16 of IEEE 802, specialising in point-to-multipoint broadband wireless access. It also is known as WiMAX, an acronym that stands for Worldwide Interoperability for Microwave Access.

Standards

There are at least four 802.16 standards: 802.16, 802.16a, 802.16-2004 (802.16), 802.16e.

Similar technologies

What differentiates WiMAX from earlier broadband wireless access (BWA) iterations is standardization. Chipsets are currently custom-built for each broadband wireless access vendor, adding time and cost to the process.

Its equivalent or competitor in Europe is HIPERMAN.

Technical advantages

WiMAX does not conflict with WiFi but actually complements it.

WiMAX is a wireless metropolitan area network (MAN) technology that will connect IEEE 802.11(WiFi) hotspots to the Internet and provide a wireless extension to cable and DSL for last mile (last km) broadband access. IEEE 802.16 provides up to 50 km (31 miles) of linear service area range and allows users connectivity without a direct line of sight to a base station. The technology also provides shared data rates up to 70 Mbit/s, which, according to WiMAX proponents, is enough bandwidth to simultaneously support more than 60 businesses with T1-type connectivity and well over a thousand homes at 1Mbit/s DSL-level connectivity. Another advantage is that traffic will be carried over Synchronous Digital Hierarchy up to the end points. This is an advantage in that it reduces latency and high capital requirements that satellite access requires.

An important aspect of the IEEE 802.16 is that it defines a MAC layer that supports multiple physical layer (PHY) specifications. This is crucial to allow equipment makers to differentiate their offerings.

Expectations

WiMAX is referred to as "WiFi on steroids". It has the potential to enable even more millions to access the Internet wirelessly, cheaply and easily. The WiMAX wireless coverage is measured in square kilometers (miles) while that of WiFi is measured in square meters (yards). A WiMAX base station would beam high-speed Internet connections to homes and businesses in a radius of up to 50 km (31 miles); these base stations will eventually cover an entire metropolitan area, making that area into a WMAN and allowing true wireless mobility within it, as opposed to hot-spot hopping required by WiFi. The proponents are hoping that the technology will eventually be used in notebook computers and PDAs. True roaming cell-like wireless broadband, however, is IEEE standard 802.20, which is compatible with WiMAX.

A further benefit of the WiMAX standard is that it relies mainly on 2 to 11 GHz bands, as opposed to the overcrowded 2.4 GHz band used by WiFi. The specifications of WiMAX avoided many of the mistakes that went into the WiFi standard, allowing longer reach, no reliance on line of sight (referred to as Non Line Of Sight, or NLOS), greater bandwith, and better encryption. The 50 km radius should be taken with a grain of salt, it would most probably only apply to a true line of sight point to point connection under ideal atmospheric circumstances.

Product release

Products are expected to be announced second quarter of 2005. As of 2004, major cities such as Seattle in the U.S.,and Dalian and Chengdu in China are already implementing WiMax.

External links

• IEEE WiMAX web site
• The WiMAX Forum web site
• Intel's White Paper: IEEE 802.16 and WiMAX
• Seattle's Pilot of WiMAX

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