WiMAX: A Tutorial
- What is WiMAX
- How WiMAX can be used for BWA
- Compare WiMAX with WiFi
- Current trends in WiMAX usage
- WiMax References
WiMAX is a short name for Worldwide Interoperability of Microwave Access. WiMAX is described in IEEE 802.16 Wireless Metropolitan Area Network (MAN) standard.
It is expected that WiMAX compliant systems will provide fixed wireless alternative to conventional DSL and Cable Internet. Typically, a WiMAX system consists of
- A WiMAX Base Station: Base station consists of indoor electronics and a WiMAX tower. Typically, a base station can cover up to 10 km radius
(Theoretically, a base station can cover up to 50 kilo meter radius or 30 miles, however practical considerations limit it to about 10 km or 6 miles).
Any wireless node within the coverage area would be able to access the Internet.
- A WiMAX Receiver - The receiver and antenna could be a stand-alone box or a PCMCIA card that sits in your laptop or computer. Access to WiMAX base
station is similar to accessing a Wireless Access Point in a WiFi network, but the coverage is more.
Several base stations can be connected with one another by use of high-speed backhaul microwave links. This would allow for roaming by a WiMAX subscriber from
one base station to another base station area, similar to roaming enabled by Cellular phone companies.
Important Wireless MAN IEEE 802.16 (WiMAX) Specifications:
Range - 30-mile (50-km) radius from base station
Speed - Up to 70 megabits per second
Non-Line-of-sight (NLoS) between user and base station
Frequency bands - 2 to 11 GHz and 10 to 66 GHz (licensed and unlicensed bands)
Defines both the MAC and PHY layers and allows multiple PHY-layer specifications.
Typical areas of application of WiMAX are as given below:
- Residential and SOHO High Speed Internet Access: The main contenders for residential and SOHO market are the DSL, and Cable Internet technologies. These
technologies have already established a market presence, and have proven track record in meeting the demands of the residential and SOHO customers. WiMAX
provides an alternative to existing access methods, where it is not feasible to use DSL or Cable Internet. Typical application will be in remote areas where
it is not economically feasible to have a DSL or Cable Internet. WiMAX is also expected to be more reliable due to wireless nature of communication between
the customer premises and the base station. This is particularly useful in developing countries where the reliability and quality of land-line communications
infrastructure is often poor.
- Small and Medium Business: The WiMAX WBA is well suited to provide the reliability and speed for meeting the requirements of small and medium size
businesses in low density environments. One disadvantage of WiMAX is the spectral limitation, in other words limitation of wireless bandwidth. For use in high
density areas, it is possible that the bandwidth may not be sufficient to cater to the needs of a large clientele, driving the costs high.
- WiFi Hot Spot Backhaul: Another area where WiMAX connectivity is for WiFi hot spots connectivity. As of now, there have been several WiFi hotspots and a
WiMAX backhaul provides full wireless solution to these wireless networks.
The mail distinction between WiFi and WiMAX is speed and coverage distances. WiFi has a typical bandwidth of 2MBps whereas WiMAX can have a bandwidth of up to
75MBps. The coverage distances also differ to a great extent. A WiFI hotspot typically covers a few hundred feet radius (fraction of a kilometer) whereas a
WiMAX can practically cover up to a distance of 10 kilometers (6 miles). One probable application of MAN is to link several WiFi networks together with WBA
(Wireless Broadband Access) using WiMAX technology.
The technology is relatively new, and several vendors are coming up with the support infrastructure. Intel and Fujitsu are among the leading providers of WiMAX compliant SoC chips. The SoCs’ can be used to
make Customer Premise Equipment (CPE) that are used to access WBA base stations. It is expected that 802.16 compliant systems would be in place by the end of 2005.