WiMAX Technology Overview
The WiMAX Forum describes WiMAX as “a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL.” “WiMAX” stands for: Worldwide Interoperability for Microwave Access. It is sometimes confused with “WiFi” due to its similar name and both being based on “802.xx” IEEE standards. WiFi is a short range technology, operating in the unlicensed 2.4 GHz frequency range and based on IEEE 802.11a.
A typical WiMAX cell can cover up to 10 Km with data rates up to 40 Mbps. A Non-Line-of-Site (NLOS) implementation can expect data rates fewer than 10 Mbps within a 2 Km radius.
The long range makes WiMAX ideal for emerging infrastructures in agriculture, construction and transportation. Its high data rate is suitable for video game controls, smart-phones, home entertainment and deployment in laptop computers and PDAs. The high Quality of Service (QoS) in conjunction with the range and bandwidth enables providers to offer Voice over IP (VOIP) calling and internet based television (IPTV) to subscribers.
The original WiMAX was based on the European ETSI HiperMAN and IEEE 802.16a standard, which operated in the 10 GHz to 66 GHz frequency range. This was later updated to 802.16d which added the 2 GHz to 11 GHz band for “fixed” and “nomadic” nodes. The most recent version, 802.16e, has provisions for “mobile” applications. The majority of equipment manufactures are developing products in the 2.3 GHz, 2.5 GHz, 3.3 GHz and 3.4 GHz – 3.8 GHz bands.
To insure interoperability, a profile based on the 256-carrier-channel OFDM (Orthogonal Frequency Division Multiplexing) PHY and a single-channel MAC (Media Access Controller) is required. Each channel is 3.5 MHz to 10 MHz of bandwidth that is dynamically allocated to a user each time a network connection is made. However, users must share the total available bandwidth in a given cell, which may present issues for high density environments.
Look for WiMAX offerings to significantly increase in 2010 as dual WiFi / WiMAX technology is incorporated into portable devices. Coupling WiMAX with existing wired and wireless services means subscribers will no longer have to make tradeoffs between network coverage and data throughput.