WIMAXWorldwide Interoperability for Microwave Access
CONTENTS Introduction Historical background Types of Wimax What can WIMAX do How WIMAX work Working scenario Advantages Disadvantages Applications Future trends Conclusion
INTRODUCTION WiMAX is short for Worldwide Interoperability for Microwave Access, and it also goes by the IEEE name 802.16.WiMAX is a wireless metropolitan area network (MAN) technology that can connect IEEE 802.11 (Wi-Fi) . The WiMAX address the "first-mile/last-mile" connection using a wireless network and therefore is a broadband wireless access (BWA) technology. It can provide a wireless alternative to cable and DSL (Digital Subscriber Line) for last mile (last km) broadband access. It is similar to Wi-Fi in concept, but it is aimed at improving performance and should permit usage over much greater distances.
HISTORICAL BACKGROUNDThere are basically three different options:1. Broadband access – This is provided by either a DSL or cable modem. This kind of access is generally used at homes etc. limitation: the main problems with broadband access are that it is pretty expensive and it doesn’t reach all areas
HISTORICAL BACKGROUND2. Wi-Fi access – In your home, you may have set up a Wi-Fi router that lets you surf the Web while you lounge with your laptop. On the road, you can find Wi-Fi hot spots in restaurants, hotels, coffee shops and libraries. Limitation : The main problem with WiFi access is that hot spots are very small, so coverage is sparse.3. Dial-up access – If you are still using dial-up, chances are that either broadband access is not available, or you think that broadband access is too expensive.
Types of WIMAXThere are mainly 2 types of WIMAX. 1. Fixed WIMAX 2. Mobile WIMAX Fixed WIMAX : is developed based on the IEEE 802.16 standard and is optimized for fixed and nomadic applications in LOS and NLOS environments. Mobile WIMAX : is based on the IEEE 802.16e standard and targeted primarily for portable and mobile applications in NLOS environment.
Types of WIMAX Line-of-sight (LOS): It is a condition where a signal travels over the air directly from a wireless transmitter to a wireless receiver without passing an obstruction.LOS connection is stronger and more stable . LOS transmission use higher frequency of rang 66GHZ. Non-Line-Of-Sight (NLOS) It a condition where a signal from a wireless transmitter passes several obstructions before arriving at a wireless receiver. The signal may be reflected, refracted, diffracted or scattered.NLOS transmission use lower frequency range of 2GHZ-11GHZ.
WHAT CAN WIMAX DO? WiMAX operates on the same general principles as WiFi — it sends data from one computer to another via radio signals. A computer equipped with WiMAX would receive data from the WiMAX transmitting station, probably using encrypted data keys to prevent unauthorized users from stealing access. It will provide the equivalent transfer rates to each user.
HOW WIMAX WORKS In practical terms, WiMAX would operate similar to WiFi but at higher speeds, over greater distances and for a greater number of users. A WiMax system consists of two parts: A WiMax tower and A WiMax receiver A WiMAX tower - Similar in concept to a cell-phone tower - A single WiMAX tower can provide coverage to a very large area -- as big as 3,000 square miles (~8,000 square km). A WiMAX receiver - The receiver and antenna could be a small box or they could be built into a laptop the way Wi-Fi access is today
COMPARISION WITH OTHERNETWORKS Wi-Fi is developedwith limited frequencyand for limited range.Range:100to 30meters.Freq:2.4 to 5.8 GHZ But WiMAX is havingwide range and frequencyRange:50km and moreFreq:2 to 11GHZ
APPLICATIONS WiMAX could allow access between anyone within range of each other ,even in areas without preexisting physical cable or telephone networks. WiMAX can operate over a wide range of frequencies including both licensed and unlicensed bands. Due to its longer range, it makes more sense for most applications to operate in licensed bands.
ADVANTAGES Offers cheap voice calls and high speed internet Ensures a boost for government security It offer fixed broadband access in urban and suburban areas where copper quality is poor or unbundling difficult The technology has been claimed to provide shared data rates up to 70 Mbit/s, but in practical maximum data rates between 500kbit/s and 2 Mbit/s
DISADVANTAGES The most common misconception is that WiMAX can offer 70 Mbps in range of 70 miles (113 kilometers) with moving stations but In practice it is valid only in ideal circumstances with only one recipient. Line of sight is needed for more distant connections. Bad weather conditions such as rain could interrupt the signal. Multiplied frequencies are used. WiMAX is a very power-consuming technology and requires significant electrical support. High installation and operational cost.
CONCLUSION WiMAX deployment will broaden to covermarkets quality have acted as a brake on extensive high-speed Internet and voice over broadband. WiMAX has thepotential to do to broadband Internet access what cellphones have done to phone access. WiMAX could replacecable and DSL services, providing universal Internetaccess. WiMAX will also be as painless as WiFi --turning your computer on will automatically connect youto the closest available WiMAX antenna.
REFERENCES WiMAX/802.16 and 802.20, ABI Research, Q4 2003 Last Mile Wireless High Speed Market, Skylight Research, March 2004 Providing Always-on Broadband Access to Underserved Areas, Alcatel Telecommunication Review (p. 127-132), Q4 2003 WiMAX forum web site: www.wimaxforum.org IEEE SPECTRUM. howstaffworks.com