WiMax, VoIP, and the Metropolitan Area Network

The emerging IEEE 802.16 standard, commonly known as WiMAX, promises to deliver last mile wireless broadband internet access capable of carrying data intensive applications, such as VoIP and streaming video, to Metropolitan Area Networks, as well as sub-urban and rural communities. WiMAX is considered a disruptive technology, designed as an alternative to fixed line DSL and coaxial technologies, and with its 802.16e revision, the cell phone networks as well.

Worldwide Interoperability for Microwave AXcess will operate over licensed and non licensed frequencies using non line of sight (NLOS) and line of sight technologies, extending broadband coverage to cities and towns wirelessly via a metro area network. Additionaly, because of its far reaching capabilities and ease of implementation, wimax is the one technology likey to bridge the Digital Divide, connecting underdeveloped regions and sparsely populated rural areas much more cost effectively than deploying a wireline infrastructure.

WiMAX and WiFi Compared

The widespread adoption of the wireless LAN in the business community, as well as the emergence of WiFi hotspots in public areas, airports, hotels and cafes, has been of tremendous significance in providing mobility to business people and consumers alike. Thanks to the open standards guided by the 802.11 committee and the WiFi Alliance, WiFi technology is becoming ingrained in our society. WiMAX plans to take WiFi a step further.

While the two technologies may sound the same, they are from their conception designed for totally different applications. WiFi is a short range standard that was designed primarily as an extension of the local area network (LAN) to provide mobility for the end user. It operates over unlicensed frequencies and has a range of about 100 meters, depending on obstructions. Typically one access point will be connected to a fixed line network, either a wired LAN or a DSL/cable broadband connection, and the range can be extended by adding more access points at appropriate distances.

WiMAX, on the other hand, is designed to function as a carrier network, or a wireless Internet service provider (WISP), blanketing whole cities and regions with broadband Internet access comparable to DSL. Coverage in optimal conditions could reach 50 kilometers, 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.

As the older more established technology, the 802.11 WiFi has been used in a mesh topology to cover larger areas such as college campuses and municipalities, for example to connect the terminals in police vehicles to their database. The emerging 802.16 WiMAX will be better suited for larger deployments, and will in fact compliment the private WiFi networks by offering a cheaper and more secure Internet access for data and voice applications.

The WiMAX Standards: Fixed, Nomadic, and Mobile

The 802.16 standard developed by the IEEE envisions a fixed wireless broadband network operating in the spectrum range of 10 GHz to 66 GHz. Originally, only the licensed spectrum was addressed in this range, and line-of-sight multipath technology was dealt with by adopting OFDM as the standard. Subsequent revisions added the 2 GHz to 11 GHz band to the spectrum, and incorporated support for non-line-of-sight technologies and Quality of Service (QoS) techniques, a prerequisite for such time sensitive applications as voice and video.

The revision known as 802.16-2004(d) rolled up all the previous revisions and then added some. Most of these original issues dealt with the Physical and Media Access Control layers, and resulted in a standards list of optional and mandatory elements by which vendors could design 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 incorporation of multiple polling techniques, ultimately reducing packet collisions and overhead.

Base stations are to support several different topologies, such as wireline backhauling, microwave point to point connections, and the ability for the WiMAX base station to backhaul itself by reserving a part of the bandwidth for that purpose.

By design, 802.16d would cater to the residential and small business markets offering wireless broadband access with speeds comparable to DSL. Enterprise markets could be served at T1/E1 data rates.

While this version of WiMax is called fixed, it is in all actuality nomadic. Users on a private WiFi network indoors could be passed off seamlessly to the publicWiMAX network when moving outdoors, their hardware determining the best network available. Devices on the WiMAX data network would include laptops, PDAs, and smart phones equipped with an on board WiMAX capable chip or PC card, utilizing the spectrum for voice, data, video, and music transfers.

Nomadic WiMAX provides for limited mobility in that the range of coverage is handled by the same base station.

WiMAX Goes Mobile

With the adoption of the 802.16e revision in late 2005, all the hype has been on Mobile WiMAX, a technology designed to compete with the cellular networks.

With major support from manufacturers like Intel, Motorola, Siemens, and Nokia among others, mobile WiMAX is built on open standards and is purported to be 4 times faster than the cellular 3G technologies (EVDO, HSDPA). Significant cost savings can be achieved for voice applications by placing calls over the Internet through VoIP.

802.16e provides for fast and seamless handoffs between base stations, with a cell radius of about 3 miles, similar to cellular networks. The standard was ratified in late 2005, and real world applications are beginning to show up in 2007, with more robust development expected throughout 2008.

Because this technology is such a threat to the legacy telecommunications industry, it is no surprise that Sprint Nextel will be deploying WiMAX as opposed to EVDO in its 4G network. Sprint has been buying up much of the WiMAX spectrum, and has recently announced a partnership with Nokia to deploy WiMAX to four Texas cities by mid 2008. This is not their first WiMAX network, and telcos around the globe have been doing the same.

The 802.16 standards are a work in progress, and as such, are subject to changes and revisions. As the standards committee works on the technology, the WiMAX Forum hopes to do what the WiFi Alliance did for the 802.11 standards, by promoting interoperability between components through testing, and offering WiMAX certification to vendors that conform to the 802.16 standards.

It should be noted that many of the WiMAX implementations at the time of this writing are proprietary, and thus do not necessarily follow the recommendations of the IEEE or the WiMAX Forum. The broadband wireless ISP Clearwire Communications has over 200,000 subscribers in 375 cites, and calls its service a WiMAX-class solution, utilizing next-generation, non-line-of-sight wireless technology. Other early adopters of pre-WiMAX technology are forging ahead, providing wireless broadband access to residential consumers and the small business market, with many companies climbing aboard the evolving standards bandwagon to assure interoperability and backwards compatibility of devices and applications.

What is Inside Wimax Technology (802.16)

WiMAX technology is identified as Worldwide Interoperability for Microwave Access; it is formed in June 2001 to encourage conformance and interoperability of the WiMAX (IEEE 802.16) standard, officially known as Wireless Metropolitan Area Network (WMAN). WiMAX technology intended to offer wireless data in a related fashion as compare to WiFi but on a outsized level and speed, therefore building national wireless networks with ease.

The driving forces behind WiMAX technology are link-to-multilink microwave networks from organizations for instance Alcatel and Siemens stay alive for years. Alternatively WiMAX offers a consistent technology according to its standard. WiMAX technology open loom could let product manufacturers make revenues of scale via producing number of WiMAX products & components to single IEEE 802.16 standard, this also allow component manufacturers buy low-cost, standards compliant components from rival component providers. This would defiantly help existing wireless service providers.

In addition, service providers lacking a mobile network can start a WiMAX technology network at comparatively stumpy price. WiMAX technology would also allow interoperability among different systems. WiMAX technology will offer high data speed network connections and in this manner serve as a backhaul for WiFi LAN (WLAN) hot spots, where people on the move can access carriers' WiFi services on mobile technology basis. WiMAX technology possibly will offer a much cheaper, easier to build network infrastructure other than the physical medium of WiFi backhauls that cable, T1 or DSL systems presently offer. These issues, together with user’s requirements for broadband facilities, will offer the grounds to markets to grow with WiMAX and wireless-broadband. However, the WiMAX technology faces some solid challenges ahead of it can become commonly accepted by users.

Because WiMAX is based on IEEE 802.16 Standard and HiperMAN, the IEEE and ETSI have each become accustomed it’s standard to take in many of the other's essential characteristics. IEEE 802.16 standard partitioned its MAC (Medium Access Control) layer into sub-layers that hold some different transport equipments and technologies, together with Ethernet, IPv4, IPv6 and other asynchronous transfer mode. This allows traders to use WiMAX technology it doesn’t matter about what technology they support for transmission. WiMAX technology has a wide communication range up to 50 kilometres because principles allows WiMAX network to transfer data at higher rates and because of this move towards use of directional antennas that generates persistent radio signals. WiMAX base station provide service to only 500 users at a time not more than that just because to they are sharing bandwidth and this factor may result in lower date rates among. Technically every single station will possibly provide communication an area inside a 10 miles radius. On the other hand WiFi has a range of only a few hundred feet while other third generation mobile networks have the range of few thousand feet.

As compare to other wireless standards their address broadcastings over particular frequency range, WiMAX network allocates data communication over several broad signal frequency ranges. The capacity to work in several ranges makes the most of the technology's ability to communicate above the frequencies that will evade interference with other wireless network applications. WiMAX system’s communication date rate and range differ a lot depending on implementation usage of frequency bands. These advantages of flexibility allow providers to employ different frequencies that depend on the speed and range needed for a particular data communication. The WiMAX technology attains higher data transmission rates in part by OFDM (Orthogonal Frequency Division Multiplexing). OFDM amplifies data capacity and bandwidth via dividing broad capacity channels to many narrowband channels; every channel uses different frequencies that can transmit different pieces of a message at the same time.

The spaces between channels are extremely close mutually other than avoiding intervention as nearby channels are orthogonal to each other and therefore no overlapping between them. The primary IEEE 802.16 standard uses the 10 to 66 GHz frequency range. On those higher frequencies WiMAX network needed a straight line of sight among senders & receivers. This factor shrinks the multi path distortion that arises when transmitting signals not follow the line of sight echoed of outsized items and finish off out of organization, in this manner jumbling the inbound communication and reducing bandwidth.

Dropping multi path distortion could therefore enhance the bandwidth. In theory WiMAX network can offer single channel data rates up to 75 Mbits/s equally on the downlink and uplink. Service providers can use several 802.16 channels for single broadcast to offer bandwidths of up to 350 Mb per second.
The accepted IEEE 802.11b WiFi WLAN technology data rate are limited to 11Mbps, on the other hand newer 802.11a and 802.11g provide upto 54Mbps in favourable conditions but practically all of the them transmit at lesser speed. Third generation mobile network technologies will support around 115 Kbps.

As far as security is concerned in WiMAX technology it uses PKI (Public Key Infrastructure) authentication, which transmit via digital certificates

by identifying parties over trusted authorities. The IEEE 802.16 system encrypts data by using 56 bit DES (Data Encryption Standard) keys. In the meantime WiMAX network is extremely scalable as it is simple to include broadcast channels to offer extra bandwidth as required.

The expenditure of setting up wireless technology is significantly increases when the wireless services are supplied at higher frequencies as the line of sight constraints required the setting up of further antennas to cover up the equivalent geographical area. The available frequencies for new wireless standards such as IEEE 802.16 are normally higher as some of the other wireless technologies are more sought-after to lower ranges that have been approved for other use.

During the development of WiMAX technology, the WiMAX Forum has strongly supported and encourage the WiMAX technology, which involves a cluster of commercial leaders such as AT&T, Cisco, Samsung, Intel, and some others giants. The WiMAX forum group's workforce is comprised of many working groups that highly focused on regulatory, marketing, technological characteristics. WiMAX product certification program was extended by the certification working group which intends to certify interoperability among WiMAX products from manufacturers internationally.

Wimax- New Upcoming Technology

WiMax is new technology mobile computing system.it work like WiFi but at higher speed for great distance and for greater number of users.WiMax is is the next generation of Wireless technology designed to enable high speed .moble internet acces to the widest array of access to the widest array of devices including notebook,PC's,Haandsets,Smart phone,and consumer electronic such as gaming devices,camcorder,music player,amd more.

WiMax is operates on 802.16 standard define by IEEE (Institute of electrical and electronics).IEEE 802.16 standard known as WMAN (Wireless Metropolitian Area Network).

WiMax can provide broadband Wireless access (BWA) upto 30miles (50km) for fixes station,3 to 10 miles (5 to 15km)for mobile station,while WiFi WLAN standard is limited in most CAses to only 100 to 300 feet (30 to 100 meter).the IEEE Wireless standard has a range of upto 30 miles and can deliver broadband at round 75 megabites/secthis is 20 times batter then any wifi connection.

WiMax is new technology so some compnies is working on Wimax.they are trying to develop Wimax chipset.WiMax is not yet as commercialized as as WiFi, but lot of work going on in WiMax market.it will going to usefull for voice and video data.by WiMax we can send voice and video data at very faster rate also we can make video call at faster rate.we are waiting for WiMax phone,gaming devices,consumer guds,music player and many other devices.it will provide as more comfert and it will change our lifestyle too so keep waiting for it.