REPORT 1

WIMAX: Worldwide Interoperability for Microwave access

What is WiMAX?

Think about how you access the Internet today. There are basically three different options:

• Broadband access - In your home, you have either a DSL or cable modem. At the office, your company may be using a T1 or a T3 line.
• WiFi access - In your home, you may have set up a WiFi router that lets you surf the Web while you lounge with your laptop. On the road, you can find WiFi hot spots in restaurants, hotels, coffee shops.
• Dial-up access - If you are still using dial-up, chances are that either broadband access is not available, or broadband access is too expensive.

The main problems with broadband access are that it is pretty expensive and it doesn't reach all areas and with WiFi access is that hot spots are very small, so coverage is sparse. What if there was a new technology that solved all of these problems? This new technology would provide:

• The high speed of broadband service.
• Wireless rather than wired access, so it would be a lot less expensive than cable or DSL and much easier to extend to suburban and rural areas.
• Broad coverage like the cell phone network instead of small WiFi hotspots.

This system is actually coming into being right now, and it is called WiMAX. WiMAX is short for Worldwide Interoperability for Microwave Access, and it also goes by the IEEE name 802.16.

WiMAX has the potential to do to broadband Internet access what cell phones have done to phone access. WiMAX could replace cable and DSL services, providing universal Internet access just about anywhere you go. WiMAX will also be as painless as WiFi -- turning your computer on will automatically connect you to the closest available WiMAX antenna.

WiMax Components:
The core components of a WiMax system are the subscriber station (SS) otherwise known as the CPE and the base station (BS). A BS and one or more SSs can form a cell with a point-to-multipoint (P2MP) structure. BS controls activity within the cell, including access to the medium by SS, allocations to achieve quality of service (QoS) and admission to the network based on network security mechanisms.
An 802.16-based system often uses fixed antenna at the subscriber station site. The antenna is mounted to the roof or an eave. Provisions such as adaptive-antenna systems (AAS) and sub-channelization are also supported optionally by the standard for enhanced link budget required for in-door installation. IEEE 802.16e sub-committee is currently working on extension to the standard required for mobility and support for the power limited SS terminals.
A BS typically uses either sectored or omni-directional antennas. A fixed SS typically uses directional antenna while mobile or portable SS usually uses an omni-directional antenna. Multiple BSes can be configured to form a cellular wireless network. When OFDM is used, the cell radius can ideally reach up to 30 miles. Practical cell sizes usually have a small radius of around 5 miles or less. The 802.16 standard also can be used in a point-to-point (P2P) or mesh topology, using pairs of directional antennas. This can be used to increase the effective range of the system relative to what can be achieved in P2MP mode

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