A WiMAX Primer
WiMAX, the Worldwide Interoperability for Microwave Access (WiMAX) is a telecommunications communications technology based on wireless transmission methods defined by the IEEE 802.16 air interface standard. Intended for Wireless Metropolitan Area Networks (WirelessMan), it can provide broadband wireless access at distances up to 30 miles for fixed stations, and up to 10 miles for mobile stations.
Potential WiMAX uses include high-speed mobile data and telecommunications services (e.g. 4G) providing a wireless alternative to cable and DSL for last-mile broadband access and connecting Wi-Fi hotspots with each other and with the internet.
To meet the requirements of different types of access, two versions of WiMAX have been defined. Both are engineered to help deliver ubiquitous, high-throughput broadband wireless services at a low cost.
Fixed WiMAX (defined in IEEE 802.16-2004) is popular with alternative service providers and operators in developing areas due to low cost of deployment, advanced performance, and ready availability of current products. Fixed WiMAX is also a possibility for backhaul of wireless base stations such as cellular, WiFi and other technologies.
Mobile WiMAX (defined in IEEE 802.16e-2005 and often referred to as "802.16e") improves on the modulation schemes defined in the Fixed WiMAX standard, and offers improved multipath performance in non-line-of-sight (NLOS) environments enabled by the adoption of SOFDMA (Scalable Orthogonal Frequency Division Multiple Access) technology. The enhancements offered over Fixed WiMAX can be attributed to many features including the following:
- Improved robustness through coverage by the use of antenna diversity techniques and HARQ (Hybrid Automatic Repeat Request)
- Use of sub-channelization to improve multipath performance
- Enhanced data security and date recovery performance through the use of coding techniques such as Convolutional Coding and Convolutional Turbo Coding
- Improved performance coverage by the use of Adaptive Antenna Systems (AAS) and Multiple Input Multiple Output (MIMO) technology.