Wimax

WiMax, also known as IEEE 802.16, is a wireless digital communications system that is intended for wireless "metropolitan area networks". WiMax is designed to extend local WiFi networks across greater distances, such as on a university campus.

The WiFi/802.11 wireless local area, which is the network standard, is limited in most cases to only about 100 to 300 feet; however, Wimax can provide broadband wireless access for up to 30 miles for fixed stations and 3 to 10 miles for mobile stations. WiMax allows for more efficient bandwidth use, interference avoidance, and is intended to allow higher data rates over longer distances.

The IEEE 802.16 standard defines the technical features of the communications protocol. The WiMAX Forum offers a means of testing manufacturer's equipment for compatibility, as well as an industry group dedicated to fostering the development and commercialization of the technology.

In the next five years, Wimax will have an enormous impact on the cellular markets, particularly that of third-world countries, as well as that of the United States. The cost-effectiveness of WiMax to that of preexisting systems is much higher. One application that can be used by cellular companies is WiMax's ability to serve as a high bandwidth "backhaul" for internet or cellular phone traffic from remote areas back to an Internet backbone; WiMax may be an answer to reducing the cost of T1/E1 backhaul as well.

What will wimax services offer to the average consumer ?

WiMAX networks will provide broadband connectivity and mobile Internet anytime, anywhere, for any device and on any network with substantial increasing data speeds for applications to include online gaming, streaming video, video conferencing, VoIP and location based services.

In the U.S., Mobile WiMax services from Sprint and Clearwire will reach more than 150 million consumers by year end 2010. In rural areas, WiMAX technology will establish an affordable and efficient broadband network. The purchase and installation process of WiMAX technology is faster, simpler and cheaper than other offered solutions. Additionally, wimax can provide coverage despite the challenges of geography and the limited footprint of wireline-based solutions. In developing countries, WiMAX technology provides the opportunity to connect people with Internet and VOIP services faster and more affordably than wireline technology.

What is the speed of wimax for end users ?

Users can expect to have broadband access speeds ranging from 1-5 Mbps depending on the service provider offering. The data rate may also depend on a number of factors, including which frequency is being used, distance of the user from the base station or node, whether there is line of site or NLoS to the base station, and the number of users on the network. There is the potential to burst to higher speeds, but that would depend on the operator's plans and business model.

Key features of Wimax

• Interoperability : A key differentiation for wimax is the interoperability of certified equipment, resulting in large economy of scale and assurance for service providers that equipment from different vendors is interoperable. 530 leading companies in the communications and computing industries, members of the Wimax Forum, are currently driving a common platform for the global deployment of IP-based broadband
• Wider coverage : The technology behind wimax has been optimized to provide excellent coverage; wider areas, better predictability of coverage and lower cost as it means fewer base stations and backhaul, simple RF planning, shorter towers and faster CPE install times.
• Lower cost : A standards based platform for wimax drives down costs and delivers volume economics to WiMAX equipment
• Industry Standard : for all usage models (fixed to mobile). Wimax was designed to become the most cost-effective solution for carriers for any usage model from fixed to mobile. Newer versions of the WiMAX standard support higher speeds of mobility and always maintain backward compatibility with previous Mobile WiMAX releases.
• Higher capacity : advantage of wimax is the use of Orthogonal Frequency-Division Multiplexing (OFDM) over CDMA which is used in older technologies like Edge, GPRS, and HSPA. OFDM delivers higher spectral efficiency and therefore higher data rate and overall system capacity.

How it works

In practical terms, WiMAX would operate similar to WiFi but at higher speeds, over greater distances and for a greater number of users. WiMAX could potentially erase the suburban and rural blackout areas that currently have no broadband Internet access because phone and cable companies have not yet run the necessary wires to those remote locations.

­ A WiMAX system consists of two parts:

• 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 PCMCIA card, or they could be built into a laptop the way WiFi access is today.

A WiMAX tower station can connect directly to the Internet using a high-bandwidth, wired connection (for example, a T3 line). It can also connect to another WiMAX tower using a line-of-sight, microwave link. This connection to a second tower (often referred to as a backhaul), along with the ability of a single tower to cover up to 3,000 square miles, is what allows WiMAX to provide coverage to remote rural areas.

What this points out is that WiMAX actually can provide two forms of wireless service:

• There is the non-line-of-sight, WiFi sort of service, where a small antenna on your computer connects to the tower. In this mode, WiMAX uses a lower frequency range -- 2 GHz to 11 GHz (similar to WiFi). Lower-wavelength transmissions are not as easily disrupted by physical obstructions -- they are better able to diffract, or bend, around obstacles.
• 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, so it'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 less interference 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 to WiMAX-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 to achieve its maximum range.

The final step in the area network scale is the global area network (GAN). The proposal for GAN is IEEE 802.20. A true GAN would work a lot like today's cell phone networks, with users able to travel across the country and still have access to the network the whole time. This network would have enough bandwidth to offer Internet access comparable to cable modem service, but it would be accessible to mobile, always-connected devices like laptops or next-generation cell phones.