The new IEEE 802.16 standard, commonly known as WiMAX , promises to provide wireless broadband Internet access for the last mile, capable of transferring data-intensive applications, such as VoIP and streaming video, to metropolitan area networks, as well as to urban and rural communities. WiMAX is considered a destructive technology, developed as an alternative to DSL and coaxial fixed-line technologies and with its 802.16e version - a cellular telephone network.
Worldwide interactive compatibility for microwave AXcess will operate on licensed and unlicensed frequencies using non-line-of-sight (NLOS) technology and direct-visiting technology, providing wireless broadband coverage to cities and towns via the metro network. In addition, because of the far-reaching possibilities and ease of implementation, wimax is one of the technologies that makes it possible to bridge the digital divide, linking the underdeveloped regions and sparsely populated rural areas is much cheaper than deploying wired communications infrastructure.
WiMAX and WiFi compared
The wide distribution of wireless networks in the business community, as well as the emergence of Wi-Fi access points in public places, airports, hotels and cafes, is of great importance for ensuring the mobility of both business people and consumers. With open standards driven by the 802.11 committee and the WiFi alliance, Wi-Fi technology is rooted in our society. WiMAX plans to make WiFi one more step.
Although both technologies may sound the same, they relate to their concept, designed for completely different applications. WiFi is a short-range standard that was designed primarily as an extension of the local area network (LAN) to provide end-user mobility. It operates at unlicensed frequencies and has a range of about 100 meters, depending on the obstacles. Typically, one access point will be connected to a fixed line network, a wired LAN or DSL broadband connection / cables, and the range can be extended by adding additional access points at appropriate distances.
WiMAX, on the other hand, is designed to work as a network of telecom operators or wireless Internet service provider (WISP), covering entire cities and regions with broadband Internet access comparable to DSL. The cover in optimal conditions can reach 50 kilometers, but in fact they are more like 5 km for users with NLOS customer service equipment (CPE) or up to 15 km with a CPE connected to the external line of sight of the antenna.
As an older technology, Wi-Fi 802.11 was used in mesh topology to cover large areas, such as college campuses and municipalities, for example, to connect terminals in police vehicles to their database. The new 802.16 WiMAX will be better suited for larger deployments and will in fact complement private Wi-Fi networks, offering cheaper and safer Internet access for data and voice applications.
WiMAX standards: fixed, code and mobile
The 802.16 standard developed by IEEE provides for a fixed wireless broadband network operating in the frequency range from 10 GHz to 66 GHz. Initially, only the licensed spectrum was considered in this range, and multipath technology with direct visibility was processed by adopting OFDM as the standard. Subsequent changes added 2 GHz to 11 GHz to the spectrum and included support for technologies other than line of sight and quality of service (QoS) technologies, which is a prerequisite for time-sensitive applications such as voice and video.
The revision, known as 802.16-2004 (d), collapsed all previous versions and then added some. Most of these initial questions are related to the physical and media access control levels and are allowed in the list of standards for optional and obligatory elements with which suppliers can create their products.
The resulting fixed WiMAX standard has a data rate of up to 40 Mbps, support for half and full duplex transmission, improved QoS and the introduction of multiple polling methods, which extremely reduces the collision of packages and overhead costs.
Base stations must support several different topologies, such as wired wire rewind, point-to-point microprocessor connections, and the ability for the WiMAX base station to rebuild, reserving part of the bandwidth for this purpose.
By design, 802.16d will serve the housing and small business markets, offering wireless broadband access at speeds comparable to DSL. Enterprise markets can be serviced at T1 / E1 data rates.
Although this version of WiMax is called fixed, it is in all actions nomadic. Users working in a private WiFi network in a room could easily disconnect from the publicWiMAX network when moving outdoors, and their hardware determines the best available network. Devices in the WiMAX data network will include laptops, PDAs, and smartphones equipped with an integrated WiMAX chip or PC card that uses a spectrum to transmit voice, data, video, and music.
Nomadic WiMAX provides limited mobility because the range of coverage is handled by the same base station.
WiMAX Goes Mobile
With the adoption of the 802.16e revision at the end of 2005, all the hype was on Mobile WiMAX, a technology designed to compete with cellular networks.
Due to the great support of manufacturers such as Intel, Motorola, Siemens and Nokia, mobile WiMAX is built on open standards and is expected to be 4 times faster than 3G cellular technologies (EVDO, HSDPA). Significant cost savings can be achieved for voice applications by placing calls over the Internet through VoIP.
802.16e provides fast and smooth handoff between base stations with a cell radius of about 3 miles, similar to cellular networks. The standard was evaluated at the end of 2005, and applications in the real world begin to appear in 2007, with more robust developments expected in 2008.
Since this technology is such a threat to the legacy telecommunications industry, it's no surprise that Sprint Nextel will deploy WiMAX, unlike EVDO, in its 4G network. Sprint is buying most of the WiMAX spectrum and recently announced a partnership with Nokia to deploy WiMAX to four cities in Texas by mid-2008. This is not their first WiMAX network, but the telecommunications company around the world is the same.
802.16 standards are unfinished and, as such, are subject to change and revision. As the standardization committee is working on technology, the WiMAX Forum hopes to do what the WiFi Alliance did for the 802.11 standards, facilitating interoperability between components through testing and offering WiMAX certification to vendors that comply with the 802.16 standards.
It should be noted that many of the implementations of WiMAX at the time of this writing are proprietary and therefore should not follow the recommendations of the IEEE or the WiMAX Forum. The ISP Clearwire Communications broadband wireless network has more than 200,000 subscribers in 375 links and calls it a "WiMAX-class solution using next-generation wireless technology without direct visibility." Other early adopters of the pre-WiMAX technology are moving forward, providing wireless broadband access to residential customers and the small business market, and many companies are rising to a growing standard platform for compatibility and backward compatibility of devices and applications.
