25-04-2011, 03:12 PM
Submitted by:
VivekYadav
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ABSTRACT
WiMAX (Worldwide Interoperability for Microwave Access) is a telecommunications protocol that provides fixed and mobile Internet access. The current WiMAX revision provides up to 70 Mbps.
WiMax has two basic functions, one is to provide privacy across the wireless network and the other is to provide access control to the network.
INTRODUCTION
WiMax stands for Worldwide Interoperability for Microwave AccessSystem.
WiMAX refers to interoperable implementations of the IEEE 802.16 wireless-networks standard , in similarity with Wi-Fi, which refers to interoperable implementations of the IEEE 802.11 Wireless LAN standard (ratified by the Wi-Fi Alliance).
WiMAX is sometimes referred to as "Wi-Fi on steroids" and can be used for a number of applications including broadband connections, cellular backhaul, hotspots, etc. It is similar to Wi-Fi but it can also permit usage at much greater distances. WiMax is more effective on a larger scale and it is more cost-effective because the cost of moving traditional broadband services to the next is more expensive.
TECHNICAL DETAILS
WiMAX Architecture
The WiMAX Forum has proposed an architecture that defines how a WiMAX network can be connected with an IP based core network, which is typically chosen by operators that serve as Internet Service Providers (ISP); Nevertheless the WiMAX BS provide seamless integration capabilities with other types of architectures as with packet switched Mobile Networks.
The WiMAX forum proposal defines a number of components, plus some of the interconnections (or reference points) between these, labeled R1 to R5 and R8:
• SS/MS: the Subscriber Station/Mobile Station
• ASN: the Access Service Network
• BS: Base station, part of the ASN
• ASN-GW: the ASN Gateway, part of the ASN
• CSN: the Connectivity Service Network
• HA: Home Agent, part of the CSN
• AAA: Authentication, Authorization and Accounting Server, part of the CSN
• NAP: a Network Access Provider
• NSP: a Network Service Provider
It is important to note that the functional architecture can be designed into various hardware configurations rather than fixed configurations. For example, the architecture is flexible enough to allow remote/mobile stations of varying scale and functionality and Base Stations of varying size - e.g. femto, pico, and mini BS as well as macros.
What is WiMax?
WiMax stands for Worldwide Interoperability for Microwave Access. It is a telecommunication technology that provides wireless transmission of data using variety of transmission modes from point to multi-point links to portable and fully mobile internet access.This technology provides up to 72 Mbit/s symmetric broadband speed without the need for cables. This technology is based on IEEE802.16 standard.WiMAX can provide broadband wireless access (BWA) up to 30 miles (50 km) for fixed stations, and 3 - 10 miles (5 - 15 km) for mobile stations. In contrast, the WiFi/802.11 wireless local area network standard is limited in most cases to only 100 - 300 feet (30 - 100m).
Working of WiMax
There is line-of-sight service, where a fixed dish antenna points straight at the WiMax tower from a rooftop or pole. The line-of-sight connection is stronger and more stable, soit's able to send a lot of data with fewer errors. Line-of-sight transmissions use higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies, there is lessinterference and lots more bandwidth WiFi-style access will be limited to a 4-to-6 mile radius (perhaps 25 square miles or 65 square km of coverage, which is similar in range to a cell-phone zone). Through the stronger line-of sight antennas, the WiMax transmitting station would send data toWiMAX-enabled computers or routers set up within the transmitter's 30-mile radius (2,800 square miles or 9,300 square km of coverage). This is what allows WiMAX toachieve its maximum range.
WiMax Infrastructure
Typically, a WiMax system consists of two parts:
• 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 10km 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 PC card that sits in your laptop or computer. Access to WiMax base station is similarto accessing a Wireless Access Point in a WiFi network, but the coverage is more.