The emerging IEEE 802.16 standard, commonly known as WiMAX, promises to last mile broadband wireless Internet access can deliver data to bear intense applications like VoIP and video streaming to metropolitan area networks and sub-urban and rural communities. WiMAX is considered a breakthrough technology as an alternative to fixed line DSL and coaxial technologies developed and 802.16 with their revision, the mobile phone networkswell.

Worldwide Interoperability for Microwave Axcess is on licensed and unlicensed spectrum to work with non line of sight (NLOS) and line of sight technologies, expansion of broadband coverage in the towns and villages wirelessly to an underground network. In addition, because it is wide-ranging capabilities and ease of deployment of WiMAX technology likey to bridge the digital divide and connecting less developed regions and sparsely populated rural areas, much cheaperProviding more effective than a wired infrastructure.

WiMAX and WiFi comparison

The widespread adoption of wireless LAN in the economy and the emergence of WiFi hotspots in public areas, airports, hotels and cafes, has a tremendous role in providing mobility, business people and consumers alike. The open standards to be guided by the 802.11 committee and the WiFi Alliance, WiFi technology is still deeply rooted in our society.WiFi WiMAX plans a step further.

While this may sound, the two technologies are the same, they are designed from its conception for completely different applications. WiFi is a short-range standard, was developed primarily as an extension of the local area network (LAN) to provide mobility for the end user. The company operates over unlicensed frequencies and has a range of about 100 meters, depending on the obstacles. Typically, an access point will be connected to a fixed network, either aWired LAN or DSL / cable broadband connection, and the range can be extended at reasonable intervals by adding more access points.

WiMAX, on the other side should be compared as a carrier network function or a wireless Internet service provider (WISP), inert entire cities and regions with broadband Internet access with DSL. Coverage under optimal conditions could reach 50 km but in reality are more like 5 km for users with NLOS customer premise equipment (CPE),or up to 15 km with a CPE connected to an external line of sight antenna.

Since the earlier established the 802.11 wireless technology in a mesh topology was used to cover larger areas such as colleges and communities, for example, to terminals in police vehicles to link to their database. The emerging 802.16 WiMAX is better suited for larger deployments, and is in fact a compliment to private WiFi networks by providing a cheaper and more secure Internet access forData and voice applications.

The WiMAX standards: Fixed, nomadic and mobile

The developed by the IEEE 802.16 standard, provides for a fixed wireless broadband network in the range of frequencies from 10 GHz to 66 GHz. Originally, only the licensed frequencies addressed in this area, and line-of-sight multipath technology has been treated with the adoption of OFDM as a standard. Subsequent revisions have the 2-GHz to 11 GHz band to the spectrum, and included support forNon-line-of-sight technologies, and Quality of Service (QoS) techniques, which is a prerequisite for such a time sensitive applications like voice and video.

The revision known as 802.16-2004 (d) rolled up all the previous revisions, and then some. Most of these initial problems with the physical and media access control layer to be treated, and resulted in a list of standard optional and mandatory elements that would allow vendors to design their products.

The resulting fixed WiMAX standard is a dataRate of up to 40 Mbit / s, support for half and full duplex transmission, better QoS, and the inclusion of several polling techniques ultimately reduce packet collisions and overhead costs.

Base stations have different topologies, such as supporting wireline backhauling, microwave point to point connections, and the ability for the WiMAX base station, is by making a portion of the backhaul bandwidth for this purpose.

The design would meet 802.16d to housing andSmall business markets offer wireless broadband access at speeds comparable to DSL. Enterprise markets could be served T1/E1 data rates.

While this version of WiMax is called fixed, nomadic, it is in all reality. Users on a home WiFi network at home, consumers will be passed seamlessly from publicWiMAX is available on the network when moving outside their hardware in determining the best network. Devices on the WiMAX data network would also laptops, PDA's and smartphones equipped with aboard of WiMAX-capable chip or PC card, use of spectrum for voice, data, video and music transfers.

Nomadic WiMAX provides for limited mobility, that the scope is handled by the same base station.

WiMAX goes mobile

With the adoption of the 802.16e revision in late 2005 has all the hype about Mobile WiMAX, developed a technology that has to compete with the cellular networks.
With great support from manufacturers such as Intel,> Motorola, Siemens and Nokia's mobile WiMAX, among other things built on open standards and is supposed to 4 times faster than 3G cellular technologies will (EVDO, HSDPA). Significant cost savings can be used for voice applications by being accessed via the Internet using VoIP.

802.16 provides a quick and seamless handover between base stations, with a radius of about 3 miles, similar to cellular networks. The standard was ratified in late 2005, and the real world applicationsbegin to show up expected in 2007 with more robust development in 2008.

Because this technology is such a threat, the legacy telecommunications industry, it is not surprising that Sprint Nextel will be using WiMAX as compared to EVDO in its 4G network. Sprint's got my most of the WiMAX frequencies, and has recently announced to set up a partnership with Nokia in WiMAX to four Texas cities by mid 2008. This is not their first WiMAX network and Telco's around theWorld have done the same.

The 802.16 standards are a work in progress, and as such are subject to changes and corrections. As the standards committee is working on the technology, hopes to do the WiMAX Forum, which the Wi-Fi Alliance for 802.11 has standards by promoting interoperability between components through testing, and offers WiMAX certification for providers that meet the standards of 802.16.

It should be noted that many of the WiMAX implementations at the time of thisLetters are proprietary and therefore not necessarily follow the recommendations of the IEEE and the WiMAX Forum. The broadband wireless ISP Clearwire Communications has over 200,000 subscribers in 375 calls, and calls its service a "WiMAX-class solution, using the next-generation non-line-of-sight wireless technology." Other early adopters of pre-WiMAX technology, progress, and offers wireless broadband access to households and small business market, with manyCompanies climb aboard the train evolving standards to ensure interoperability and backward compatibility of the devices and applications.

Author Michael Talbert is a certified systems engineer and web designer with over 7 years experience in the industry. For more information on VoIP, WiMAX and related technologies on the web site VoIP Facts.net for the latest industry news and comments.

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