What is WiMax? What is the difference bet Wifi-WiMax-WiBro?

What is WiMax?

    The two driving forces of modern Internet are broadband, and wireless. The WiMax standard combines the two, delivering high-speed broadband Internet access over a wireless connection. Because it can be used over relatively long distances, it is an effective "last mile" solution for delivering broadband to the home, and for creating wireless "hot spots" in places like airports, college campuses, and small communities.
Based on the IEEE 802.16 Air Interface Standard, WiMax delivers a point-to-multipoint architecture, making it an ideal method for carriers to deliver broadband to locations where wired connections would be difficult or costly. It may also provide a useful solution for delivering broadband to rural areas where high-speed lines have not yet become available. A WiMax connection can also be bridged or routed to a standard wired or wireless Local Area Network (LAN). 

     The so-called "last mile" of broadband is the most expensive and most difficult for broadband providers, and WiMax provides an easy solution. Although it is a wireless technology, unlike some other wireless technologies, it doesn't require a direct line of sight between the source and endpoint, and it has a service range of 50 kilometers. It provides a shared data rate of up to 70Mbps, which is enough to service up to a thousand homes with high-speed access.      WiMax offers some advantages over WiFi, a similar wireless technology, in that it offers a greater range and is more bandwidth-efficient. Ultimately, WiMax may be used to provide connectivity to entire cities, and may be incorporated into laptops to give users an added measure of mobility.
     WiMax requires a tower, similar to a cell phone tower, which is connected to the Internet using a standard wired high-speed connection, such as a T3 line. But as opposed to a traditional Internet Service Provider (ISP), which divides that bandwidth among customers via wire, it uses a microwave link to establish a connection.
     Because WiMax does not depend on cables to connect each endpoint, deploying WiMax to an entire high-rise, community or campus can be done in a matter of a couple days, saving significant amounts of manpower. Source:wiseweek  
Difference ???

     While nearly all types of wireless networking can seem confusing, there are some simple things to keep in mind about the difference between the wireless standards known as WiFi, WiMAX, and WiBro™. Each one is similar in that each provides a way to connect to a wireless network for workstation communication or Internet access. Each technology may be seen as an improvement from the previous one as well.

    WiFi, which stands for wireless fidelity, is known as the 802.11 wireless standard. There are a number of sub-series such as the 802.11(a)(b) or (g). The subsequent generations of this technology have increased the speed and range. Its most common use is to provide wireless Internet to users of notebook computers. Even with the advances in WiFi, however, there are a number of limitations.

    WiFi has some inherent disadvantages. For example, while WiFi can work well in localized locations, the routers used for the connections do not have a tremendous amount of range. In most cases, 300 feet (approximately 100 meters) is about the limit of the technology. Therefore, for larger wireless networks and connectivity, another standard was needed. These limitations are one reason municipal wireless networks have largely failed.

    WiMAX, short for Worldwide Interoperability for Microwave Access, is a different standard known as the 802.16. It allows only so many users on the standard and then will cut off any additional users trying to use the connection. This is different that WiFi, which will allow, theoretically, a limitless number of users on, which in turn will bog down the system. Despite this, the biggest difference is the range. For non-line of sight, the range is 25 square miles (65 square kilometers). For line of sight between the transmission point and receiving antenna, the range jumps up to 2,800 square miles (9,300 square kilometers).

    WiBro™, which stands for Wireless Broadband, is very similar to WiMAX. The transmission speeds are much the same, but the main difference is that WiBro™ can track a receiver that is moving from place to place. It may also be called mobile WiMAX. It is not truly mobile in the sense that it can be used effectively while the receiver is moving at high rates of speed. Rather, it simply means the receiver can move from place to place and experience no degradation in service, as long as the receiver stays within range. WiMAX does not offer this because it needs a stationary antenna in order to receive a signal. 

    One thing to keep in mind about WiBro™ is that it is still under development. As it improves, there may come a time when the receivers will be able to maintain connections even while traveling at high rates of speed. In those cases, it may call for a completely different standard altogether with a completely different name. Source: wisegeek
WiFi vs. WiMax:

   Comparing WiMax to WiFi is akin to comparing apples to oranges. Initially it’s easy to see why the comparison would exist, as most people think WiMax is merely a more robust version of WiFi. Indeed they are both wireless broadband technologies, but they differ in the technical execution and ultimately their business case is very different. In addition to the technical differences that exist, the marketplace difference is that equipment is more or less non-existent for WiMax and certainly not geared towards a residential environment with very high pricing to be expected. It will take at least 2 years to see equipment of mass market uptake pricing.

     WiMax will not be commercially available until the second half of 2005, and even then at a very controlled level. This is primarily due to standardization issues. In fact, it won’t be until 2006 that a robust production and implementation will happen due to the ramp-up period for manufacturers. This is certainly one challenge to the widespread adoption of WiMax. Additionally, WiMax will have issues of pricing, and will remain far more expensive than WiFi. WiMax will be primarily adopted by businesses to replace or displace DSL, and offices that want to cover a lot of territory without entering the world of endless repeaters that are necessary with the 802.11 technologies. It will take some time (2 years) for WiMax to significantly reduce its price-point for residential uptake.  WiMax will not displace WiFi in the home because WiFi is advancing in terms of speed and technology. Each year brings a new variant to the 802.11 area with various improvements.

    Additionally, for commercial deployment, frequency allocation will be an issue. With the three dominant communications players controlling the best frequencies, it will be hard to get the type of traction needed with the remaining companies operating in the frequencies available. WiMax will become extremely robust and displace WiFi as the deployment of choice for commercial deployments, but that won’t even begin until the end of 2006. Based upon the number of public hotspots already deployed, WiMax will not be chosen to replace those as they are up and running adequately and personnel involved understand how to work with the technology. The business case does not exist at the hotspot level. Where it may exist is for wider free use deployments such as city deployments (free ones) and other government sponsored or carrier sponsored (with ultra inexpensive pricing for consumers) deployments. If this happens then its not only WiFi that will be displaced, but cable and DSL will also lose a percentage of their subscriber base. What will cause the displacement is the consumer’s proven desire for a bundled package. Source: