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21-12-2009, 01:18 PM
Abstract. The term WIMAX (Worldwide Interoperability for Microwave Access) has become synonymous with the IEEE 802.16 Wireless Metropolitan Area Network (MAN) air interface standard. Filling the gap between Wireless LANs and wide area networks, WIMAX-compliant systems will provide a cost-effective fixed wireless alternative to conventional wire-line DSL and cable in areas where those technologies are readily available. The WIMAX technology can provide a cost-effective broadband access solution in areas beyond the reach of DSL and cable.
The ongoing evolution of IEEE 802.16 will expand the standard to address mobile applications thus enabling broadband access directly to WIMAX-enabled portable devices ranging from smart phones and PDAs to notebook and laptop computers. Thus WIMAX is going to be a revolution in the world of communications. First of all, it will suppose an explosion of the wireless data networks, being not a substitute but a complement to Wi-Fi, and if technology advances enough to get a good intercity wireless link, these networks could be comparable to the internet. It will mean also revolution in the world of mobile communications, being a serious competitor with UMTS. WIMAX Forum Certified products will extend the range of Wi-Fi networks from the local area to the metropolitan area and beyond. These products will be based upon the 802.16 standard and will support distances of up to 50 kilometers â€œ far longer distances than supported by Wi-Fi products.
Itâ„¢s hard to buy a laptop computer today that doesnâ„¢t come with a Wi-Fi chip: a built-in radio that lets users surf the Web wirelessly from the boardroom, the bedroom, or the coffee bar. People love Wi-Fi because a single base station - a box with a wired connection to the Internet, such as a DSL, cable, or T1 line can broadcast to multiple users across distances as great as 100 meters indoors and 400 meters out-doors. But thereâ„¢s a new technology on the way that will make Wi-Fi look feeble. ITâ„¢S CALLED WiMAX.
AND WiMAX provides wireless broadband Internet connections at speeds similar to Wi-Fi - but over distances of up to 50 kilometers from a central tower. Metropolitan area wireless networking at broadband speeds isnâ„¢t new, but the specialized equipment that receives the broadband signals has typically been too expensive for everyone but large businesses. Now that U.S. computing and communications firms are gradually reaching consensus on the details of the WiMAX standard, however, those prices could come down significantly. Industry agreement on details such as how to encrypt WiMAX signals, which frequencies to use, and how to provide multiple users with access to those frequencies will finally allow companies like Intel to manufacture mass quantities of WiMAX-enabled chips for use in broadband wireless equipment. And thatâ„¢s expected to eventually bring WiMAX receivers into the $50 to $100 price range of todayâ„¢s DSL and cable modems, meaning that millions of users could eventually drop their current Internet
Service Providers - often local phone or cable companies - and simply access the Internet over rooftop antennas at the other end of town.
WHAT IS WIMAX?
WiMAX is a wireless metropolitan-area network technology that provides interoperable broadband wireless connectivity to fixed, portable and nomadic users. It provides up to 50- kilometers of service area, allows users to get broadband connectivity without the need of direct line-of-sight to the base station, and provides total data rates up to 75 Mbpsâ€ enough bandwidth to simultaneously support hundreds of businesses and homes with a single base station. This white paper discusses wireless metro-access technologies: Wi-Fi with high gain antennas, Wi-Fi meshed networks and WiMAX. It explores how the technologies differ and how they can be combined to provide a total last-mile access solution now and in the future.
WiMAX is the moniker used for the IEEE 802.16 wireless interface specifications promoted by the industry trade organization ËœForum for Worldwide Interoperability for Microwave Accessâ„¢. Members of the WiMAX Forumâ€žÂ¢ include leading operators, equipment and component makers. The WiMAX Forum ratified the new standard for wireless broadband access at the beginning of 2003. WiMAX continues to be one of the most talked about technologies.
WiMAX is a standard-based technology which will serve as a wireless extension or alternative to cable and DSL for broadband access. Particularly for end users in rural, sparsely populated areas or in areas where laying cable is difficult or uneconomical, WiMAX will provide a new broadband access path to the internet. But companies and communities along with ownerâ„¢s notebooks will benefit from WiMAX as well if they require mobile networks that cover a larger area than Wi-Fi. As an industry standard, 802.16 enables equipment suppliers to build solutions that can interoperate with each other, leading to lower cost and investment risk. WiMAX is going to bring scale to the market and, ideally, create a larger market along the way. Since wireless technologies are easier to install than wire-based infrastructures, providers can use WiMAX to provide broadband access in previously under-supplied areas quickly and cost-effectively. WiMAX is not a new technology, but rather a more innovative and commercially viable adaptation of a proven technology that is delivering broadband services around the globe today. In fact, wireless broadband access systems from WiMAX Forum members are already deployed in more than 125 countries around the world. These leading equipment providers are on a migration path to WiMAX.
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09-02-2010, 04:44 PM
WiMAX (Worldwide Interoperability for Microwave Access) is the next step on the path to a wireless world, extending broadband wireless access to new areas and over farther distances, as well as considerably reducing the expenditure of deploying broadband to new locations. WiMAX is a wireless digital communications system, also known as IEEE 802.16 that is intended for wireless "metropolitan area networks". WiMAX can provide broadband wireless access (BWA) up to 30 miles (50 km) for fixed stations, and 3- 10 miles (5 -15 km) for mobile stations. In contrast, the WiFi/802.11 wireless local area network standard is limited in most cases to only 100 -300 feet (30 - 100m). WiMAX is the industry term for a long-range networking standard. WiMAX technology has potential to deliver the high-speed Internet access to rural areas and other locations not serviced by cable or DSL technology. WiMax offers an alternative to satellite Internet services.
Seminar Report On WiMAX Submitted by: SAVITHA K.S Reg. No. 56437 2005-2006
WiMAX (Worldwide Interoperability for Microwave Access) is the step on path to a wireless world, extending broadband wireless access to new areas and over farther distances, as as considerably reducing the expenditure of deploying broadband to new locations. WiMAX is a wireless digital communications system, also known as I 16 that is intended for "metropolitan area networks". WiMAX can provide broadband access (8WA) up to 30 miles (50 km) for fixed stations, and 3 10 miles -15 km) for mobile stations. In contrast, the WiFi/B02.11 wireless local area network standard is limited in most cases to only 100 -300 (30 100m). WiMAX is the industry term for a long-range networking standard. WiMAX technology has potential deliver the high-speed Internet access to rural areas and other locations not by or DSL technology. WiMax offers an alternative to satellite Internet services.
2. WIRELESS NETWORKING The term wireless networking refers to technology that enables two or more computers to communicate using standard network protocols but without network cabling. Strictly speaking, any technology that does this could be called wireless networking. The current buzzword however generally refers to wireless LANs.This technology, fuelled by the emergence of cross-vendo industry standards such as IEEE 802.11, has produced a number of affordable wireless solutions that are growing in popularity with business and schools as well as sophisticated applications where network wiring is impossible, such as in warehousing or point-of-sale handheld equipment. There are two kinds of wireless networks: <8 An ad-hoc or peer-to-peer wireless network consists of a number of computers each equipped with a wireless networking interface card. Each computer can communicate directly with all of the other wireless enabled computers. They can share files and printers this way, but may not able to access wired LAN resources unless one of the computers acts as bridge to the wired LAN using special software (this is called "bridging"). <8 A wireless network can also use an access point or base station. In this type of network the access point acts like a hub, connectivity for the wireless computers. It can connect or bridge the wireless LAN to a wired LAN allowing wireless computer access to LAN resources such as file servers or existing internet connectivity.
There are two types of access points: Â¢ Dedicated hardware access points such as Lucent's WaveLAN, Apple's Airport Base Station or Web Gear's Aviator PRO. Â¢ Software access points which run on a computer equipped with a wireless network interface path as used in adhoc or peer to peer wireless network.
IEEE WIRELESS COMMUNICATIONS STANDARDS 3.1 802.11
Working Group for Wireless Local Area Networks are standards 11 specify an the -year" interface a wireless client and a base station or access point, as well as among wireless clients. The 802.11 can be compared to 802.3 standard for Ethernet for wired LANs. The IEEE 802.11 specifications address both the Physical (PHY) and Medium Control (MAC) layers and between manufactures are tailored compatibility of 3.2 802.15 Working Group for wireless Personal Area Networks The 802.15 Working Group in the IEEE 802 family, for low complexity low power consumption wireless In March 1998, Wireless Personal Network (WPAN) study group was . In May 1998, Bluetooth Group (SIG) was formed, and in May 1999 the WPAN Study Group 802.15, the WPAN Working In July 1999, Bluetooth the Bluetooth Specification v1 3.3 802.16 Working Group for Broadband Wireless Access Standards 16 specifications support development of fixed broadband access systems to rapid world wide deployment of innovative, cost -effective interoperable multi-vendor broadband wireless access products.
3.4 P1451.5 Working Group for Wireless Sensor Standards Many companies are developing various wireless communication interfaces and protocols for sensors. An openly defined wireless transducer communication standard, that can accommodate various existing wireless technologies, will reduce risk for users, transducer manufacturers, and system integrators. It will enhance the acceptance of the wireless technology for transducers connectivity. The standard will define Transducer Electronic Data Sheets (TEDS) based on the IEEE 1451 concept, and the protocols to access TEDS and transducer data. It will adopt necessary wireless interfaces and protocols to facilitate the use of technically differentiated, existing wireless technology solutions. It will not specify transducer design signal conditioning, wireless system physical design or use, or use of TEDS. WiF" 801. Bluetooth 801 '
WiMAX 4. 802.16 STANDARD 4.1
THE 802.16 WORKING GROUP Development of IEEE standard 802.16 and the included wireless MAN air interface along with associated standards amendments,is the responsibility of IEEE Working group 802.16 on Broadband wireless access (BWA) standards. The working group's initial interest was the 10-66 GHz range. The 2-11 GHz amendment project and implimentation that led to IEEE 802.16a was approved in march 2000. The 802.16a project and implimentation primarily involves the development of new physical layer specification with supporting enhancements to the basic MAC. In addition the working group has completed IEEE standard 802.16.2 . ( " Recommended Practice for Coexistence of Fixed Broadband Wireless Access Systems") to address 1 0-66 GHz coexistence and, through the amendment project and implimentation 802.16.2a is expanding its recommendations to include the licensed bands from 2 to 11 GHz. 4.2 LAYERS OF 802.16 MEDIUM ACCESS CONTROL The IEEE 802.16 protocol was designed for point to multipoint broadband wireless access applications. It addresses the need for very high bit rates,both the uplink (to the BS) and the downlink (from the BS). Access and bandwidth allocation algorithms must accommodate hundreds of terminals per channel, with terminals that may be shared with the multiple end users. The services required by these end users are varied in their nature and include legacy time division multiplexing (TOM) voice and data, Internet protocol (IP) connectivity, and packetized voice over IP (VoIP). To support this variety of services the 802.16 MAC must accommodate both the continuous and the bursty traffic. Additionally these services expect to be
WiMAX with traffic types.The 802.16 ,.,.,..,..",H.n assigned QoS in the wide analogous the asynchronous transfer (ATM) service categories as well as newer categories such as frame rate (GFR). The 802.16 MAC protocol must also support a variety of backhaul requirements including both asynchronous transfer (ATM) and packet based convergence sub layers are to map the transport layer traffic to a MAC that is flexible Through such enough to efficiently carry any as payload header packing and fragmentation, convergence sub layers and MAC work together to carry traffic in a form that is often more than the original tra mechanism. Along the fundamental task of allocating bandwidth transporting data, the MAC includes a privacy sub layer that provides the authentication network access and connection establishment to avoid theft of and it provides key and encryption for data privacy. To accommodate more demanding physical environment and different requirements of the frequencies 2 and 11 GHz, the 802.16a project and implimentation upgrading the MAC to provide automatic request (ARQ) and support mesh, rather than the only point multipoint, network architectures.
WiMAX THE PHYSICAL LAYER 10-66 GHz-In the design of the PHY specification for 10-66 GHz, line-of-sight propagation was deemed a -practical necessity. With this condition assumed, single -carrier modulation was easily selected; the air interface is designated-ed "Wireless MAN-Sen. Many fundamental design challenges remained, however. Because of the point-multipoint architecture, the BS basically transmits a TOM signal with individual subscriber stations allocated time slots serially. Access in the uplink direction is by time-division multiple accesses (TOMA). Following extensive discussions regarding duplexing, a burst design was selected that allows both time-division duplexing(TOO) , in which the uplink and the downlink share a channel but it do not transmit simultaneously and the FOO in which the uplink and the downlink operate on separate channels, sometimes simultaneously. This burst design allows both TOO and FOO to be handled in a similar fashion. Support for half duplex FO subscriber stations, which may be less expensive since they does not simultaneously transmit and receive is added at the expense of some slight complexity. Both TOO and FDD alternatives support adaptive burst profiles in which modulation,coding options may be dynamically assigned on a burst by burst basis. 2-11 GHz: -the 2-11 GHz bands both licensed and license exempt are addressed in IEEE project and implimentationB02.16a.The standard is in ballot not yet complete. The draft currently specifies that compliant systems implement one of three air interfaced specifications, each of which provide for interoperabilityDesign of the 2-11 GHz physical layer is driven by the need for the non line of sight (NLOS) operation. Because residential applications are expected, roof tops may be too low for a clear sight line to a BS antenna, possibly due to the
WiMAX obstruction by trees. Therefore, significant multipath propagations must be expected. Furthermore, outdoor -mounted antennas are expensive due to both hardware and installation costs. The three 2-11 GHz air interface specifications in 802.16a are: -Wireless MAN SC-2: This uses a single carrier modulation format. -Wireless MAN-OFDM: This uses orthogonal frequency division multiplexing with a 256 point transform. Access is by TDMA.This air interface is mandatory for license exempt bands. -Wireless MAN-OFDMA: This uses orthogonal frequency division multiple access with 2048 point transform. In this system multiple access is provided by addressing a sub set of multiple carriers to individual receivers. Because of the propagation requirements, the use of advanced antenna systems is supported. 4.3.802.16: what features it supports WiMAX supports both time division duplex and frequency division duplex (FDD) modes of operation on air, along with a range of channel bandwidths. The OFDM PHY mode, which is also known Wireless MAN-OFDM, is specified for use between 2 and 11 GHz. The 802.16 MAC controls access of the BS and SSs to the air through a rich set of features. The on-air tuning is based on consecutive frames that are divided into slots. The size of frames and the size of individual slots within the frames can be varied on a frame-by-frame basis,under the control of a scheduler in the BS. This allows the effective allocation of on -air resources to meet the demands of the active connections with their granted QoS properties.
802.16 MAC provides a connection oriented to upper of the protocol Connections that are granted and by the MAC. connections can by the SS making to the to them while a connection is maintained. service in the 802.16 MAC takes one of four forms: bit rate grant,real polling,non real time polling and best effort-Media access control packet units (MPDUs) are transmitted on -PHY slots. MPDUs , the MAC service units (MSDUs) are MSDUs are packets the top of the MAC layer above . MPDUs are the transferred between the bottom of the MAC and the PHY layer below. . Within MPDUs MPDUs, MSDUs can be , MSDus can (aggregated) . of MSDUs can be packed within a single packed MPDU. Automatic retransmission request(ARQ) can be used to request retransmission of the unfragmented MSDUs and fragments of MSDUs. nOI"Tl"\rrnc authentication, key MAC a privacy sub that encryption of MPDUs. of the 802.16 protocoi is shown is Figure. Computerscience
MAC Convergence Sub layer (ATM Ethernet 802.1Q.IP) MAC MAC Privacy Sub layer Physical Layer ATM Ethernet 802.1 Q I nternet Protocol Packing Fragmentation ARQ OoS Authentication Key Exchange Privacy (encryption) OFDM, ranging, Power control, DFS Figure: Diagram illustrating the layers of 802.16 protocol
Through the use of flexible PHY modulation and coding options, flexible frame and slot allocations, flexible OoS mechanisms, packing, fragmentation and ARO, the 802.16 standard can be used to deliver broadband voice and data into cells that may have a wide range of properties. This includes a wide range of population densities, a wide range of cell radii and a wide range of propagations environments. Convergence sub layers at the top of the MAC enable Ethernet, ATM,TDM voice and IP(lnternet Protocol) services to be offered over 802.16.
5. CORE COMPONENTS OF WIMAX SYSTEM Designed from the Group Up for Metropolitan Area Networks: In January 2003 , the IEEE approved the 802.16 a standard which covers frequency bands between 2GHz and 11 GHz .This standard is an extension of the IEEE 802.16 standard for 10-66 GHz published in April 2002. These sub11 GHz frequency ranges enable non line-ofsight performance, making the IEEE802.16a standard the appropriate technology for last-mile applications where obstacles like trees and buildings are often present and where the base stations may need to be unobtrusively mounted on the roofs of homes or building rather than towers on mountains. The core components of WiMAX system are the subscriber station( SS) otherwise known as the CPE and the base station (BS ).A BS and one more SSs can form a cell with a point-to-multipoint (P2MP) structure. On air, the BS controls actively within the cell, including access to the medium by SSs, allocations to achieve the quality of service (OoS) and admission to the network based on network security mechanisms.
SYSTtM An 802.16-based system often uses fixed antenna at the subscriber station site. The antenna is mounted to the roof or an eave. Provisions such as adaptive antenna systems (AAS) and subchannelization are also supported optionally by the standard for enhanced link budget required for in-door installation. IEEE 802.16e sub-committee is currently working on extension power limited SS terminals. A BS typically uses either sectored/directional or omni~directional antennas. A fixed SS typically uses directional antenna while mobile or portable SS usually uses an omni-directional antenna. Multiple BSs can be configured to form a cellular wireless network. When the Orthogonal Frequency Division Multiplexing (OFDM) is used, the cell radius can ideally reach up to 30 miles, however this requires a favorable channel environment and only the lowest data rate can be achieved. Practical cell sizes usually have a small radius of around 5 miles or less. The 802.16 standard also can
be used in a point-to-point (P2P) or mesh topology, using pairs of directional antennas. WiMax base stations will have the ability to provide approximately 60 businesses with T1 access and hundreds of homes with DSLlCable speed access in theory. Engineers are stating that WiMax has the capability of reaching 30 Miles but real world testing has shown 4-8 mile working radius. WiMax line of sight antennas operate at a higher Frequency up to 66mhz. Distribution antennas do not have to be in the line of sight with their clients . Non line of sight towers operate on a range similar to Wi-Fi . WiMax can operate right next to cell phone towers with no interference. HOW WIMAX WORKS J
WiMAX With shared rates up to 75 Mbps ,a single "sector" of an 802.16a base station-where sector is defined as a single transmiUreceive radio pair at the base station-provides sufficient band width to simultaneously support more than 60 business with T1-level connectivity and hundreds of homes with the DSL rate connectivity, using 20 MHz of the channel bandwidth. To support a profitable business model, operators and service providers need to sustain a mix of high revenue business customers and the high volume residential subscribers. 802.16a helps meet this requirement by supporting the differentiated service levels, which can include guaranteed T1 level services for business, or best effort DSL-speed service for home consumers. The 802.16 specification also includes robust security features and the Quality of Service needed to support services that require low latency, such as voice and video. 802.16 voice service can either be the traditional Time Division Multiplexed (TOM) voice or Voice over IP (VoIP).
6, WiMAX FORUM WiMAX Forum may be as the exclusive organization dedicated to certifying the interoperability of BWA products, the WiMAX defines and conducts conformance and the interoperability ensure that different vendor systems work seamlessly with one another.The WiMax Forum to support wireless metropolitan-area networking products based on the 16, much as the Wi-Fi Alliance has done for LANs and 11. that pass conformance and interoperability achieve the "WiMAX Forum Certified" designation and display mark on products and the marketing materials. Vendors claiming their equipment is that 'WiMAX-ready," "WiMAX-compliant," "pre-WiMAX," are not WiMAX Forum Certified, according to the Forum. WiMAX is defined as Worldwide Interoperability for Microwave ''''''-',,,..::>..::> by the WiMAX Forum, April 2001 to promote conformance and interoperability of the standard 802.1 The Forum describes WiMAX as" a standards-based technology enabling the delivery of mile wireless broadband access as an alternative to and DSL." The WiMAX Forum ,working to facilitate the deployment of broadband wireless networks based on the I 802.16 standard by helping to ensure the compatibility and interoperability of broadband access equipment.The organization is a nonprofit association formed in June 2001 by equipment and component suppliers for promoting adoption of I 802.16 compliant equipment by operators of broadband wireless access systems.
Principles: WiMAX Forum is comprised of the industry leaders who are committed to the open interoperability of all products used for broadband wireless access. Â¢ Support IEEE 802.16 standard Â¢ Propose and promote access profiles for their IEEE 802.16 standard Â¢ Certify interoperability levels both in network and the cell Â¢ Achieve global acceptance Â¢ Promote IJse of broadband wireless access overall The WiMAX Forum is the only organization bringing compliance and interoperability to wireless broadband industry with testing and certification program, WiMAX Forum Certified. Why WiMAX Forum Certified? Today every solution is custom and not interoperable. Every piece of WiMAX Forum Certified equipment will be interoperable with the other WiMAX Forum Certified equipment. WiMAX Forum Certified means a service provider can buy equipment from more than one company and be confident that everything works together. WiMAX Forum Certified means a more competitive industry. WiMAX Forum Certified means lower costs. WiMAX Forum Certified means faster growth for broadband wireless -everywhere around the globe.
WiMAX Technology WiMAX is a standards-based technology enabling Â¢ the delivery of last mile wireless broadband access as an alternative to cable and DSL. WiMAX will provide fixed, nomadic, consistent, portable and eventually the mobile wireless broadband connectivity without the need for directs line-of-sight with a base station. In a typical cell radius deployment of three to ten kilometers, WiMAX Forum Certified systems can be expected to deliver capacity of up to 40 Mbps per channel, for the fixed and portable access applications. This is enough bandwidth to simultaneously support hundreds of business with T -1 speed connectivity and thousands of residences with DSL speed connectivity. Mobile network deployments are expected to provide up to 15 Mbps of capacity within a typical cell radius deployment of up to three kilometers. It is 'expected that WiMAX technology will be incorporated in notebook computers and PDAs by 2007, allowing for the urban areas and cities to become "metro zones" for portable outdoor broadband wireless access. WiMAX Forum Certified equipment is expected to provide up to 50-kilometers of range and allow users to receive broadband connectivity without requiring a direct line of sight with the base station. The equipment is also expected to provide shared data rate up to 70Mpbs, which is enough bandwidth to simultaneously support more than 60 businesses with T1 type connectivity and hundreds ot homes with DSL-type connectivity with a single base station.
7. WIMAX AND WIFI The IEEE 802.16 media access controller (MAC) is significantly different from that of IEEE 802.11 Wi-Fi MAC. In Wi-Fi, the MAC uses contention access all subscriber stations wishing to pass data through an access point are competing for the AP's attention on a random basis. This can cause distant nodes from the AP to be repeatedly interrupted by less sensitive, closer nodes, greatly reducing their throughput. And this makes services , such as VolP or IPTV which depend on a determined level of quality of service (OoS) difficult to maintain for large numbers of users. Â¢ WI-RNflWORkARCHITECTUREDIAGRAM A recent addition to the WiMAX standard is theunderway which will add full mesh networking capability by enabling WiMAX nodes to simultaneously operate in the "subscriber station" and "base station" mode. This will blur that initial distinction and allow for widespread adoption of WiMAX based mesh networks and promise widespread WiMAX adoption. WiMAX/802.16's use of OFDMA and scheduled
WiMAX .. Â¢ MAC allows wireless mesh networks to be much more robust and reliable. These differences between and the evolution of Wi-Fi and WiMAX mesh networks could serve as a separate Wikipedia topic. The original WiMAX standard,IEEE 802.16, specifies WiMAX in the 10 to 66GHz range. 802.16a ,updated in 2004 to 802.16-2004, added support for the 2 to11 GHz range, of which most parts are already unlicensed internationally and only very few still require domestic licenses. Most business interest will probably be in the 802.16-2004 standard , as opposed to the licensed frequencies. The WiMAX specification improves upon many of the limitations of the WiFi standard by providing increased bandwidth and stronger encryption. It also aims to provide connectivity between the network endpoints without direct line of sight in some circumstances. The details of performance under the non-line of sight (NLOS) circumstances are unclear as they have yet to be demonstrated. It is commonly considered that spectrum under 5-6 GHz is needed to provide reasonable NLOS performance and cost effectiveness for PtM (point to multi-point) deployments. WiMAX makes clever use of multi-path signals but does not define the laws of physics. WiMAX is a wireless digital communications system, also known as IEEE 802.16 that is intended for wireless "metropolitan area networks". WiMAX can provide broadband wireless access (BWA) up to 30 miles (50 km) for fixed stations, and 3 -10 miles (5 -15 km) for mobile stations. In contrast, the WiFi/802.11 wireless local area network standard is limited in most cases to only 100 -300 feet (30 100m). With WiMAX and WiFi-like the data rates are easily supported, but the issue of interference is lessened. WiMAX operates on both
licensed and non-licensed frequencies, providing a regulated environment and viable economic model for wireless carriers. WiMAX can be used for wireless networking in much the same way as the more common WiFi protocol. WiMAX is a second-generation protocol that allows for more efficient bandwidth use , interference avoidance ,and is intended to allow higher data rates over longer distances. WiMax is not a replacement for Wi-Fi hotspot and home networking technologies primarily for cost reasons. WiMax (802.16e) is a newer standard of wireless networking designed to provide the last mile of high speed internet access to the end user. Some people would call WiMAX WiFi on steroids but this would be to broad of an assessment . Wi-Fi was and still will be used in LAN environments for the foreseeable future. WiMax was designed to provide (MAN) Metropolitan Area Access, to the homes and businesses. WiMax (MAN) deployments are similar to a Wi-Fi network. First the ISP would have their T3 or higher access. The ISP would then use line of sight antennas (Bridges) to connect to towers that would distribute the non line of sight signal to (MAN) residential/business clients. WiMax line of sight antennas operate at a higher Frequency up to 66mhz. The Distribution antennas do not have to be in the line of sight with their clients. Non line of sight towers operate on a range similar to Wi-Fi . WiMax can operate right next to cell phone towers with no interference. Wi Max networks are similar to the Wi-Fi in deployment. The WiMAX Base station or Tower will beam a signal to a WiMax
Receiver. Similar to a Wi-Fi access point sending a signal to a laptop. As far as I can tell laptops will be shipping with the WiMAX receivers in 2006. QOS (Quality of Service) is an major issue with WiMax because of the number of people accessing a tower at once. Some would think that a tower could be easily overloaded with a lot of people accessing it at once. Built into the WiMax standard is an algorithm that when the tower/base station is nearing capacity then it automatically will transfer the user to another WiMax tower or cell. Unlike a Wi-Fi clients who have to kind of fight to stay associated with a given access point; WiMax will only have to perform this hand shake at the MAC level the first time they access the network. WiMax is designed for building a network infrastructure when the environment or distance is not favorable to a wired network. WiMax is a cheaper and quicker alternative than having to lay wire. Third world country will greatly benefit from deploying WiMax networks . WiMax can handle virtually all the same protocols Wi-Fi can include the VOIP. African countries are now going to start deploying WiMax networks instead of cell phone networks. Disaster zones can also utilize WiMax giving them the ability to distribute crisis information quickly and cheaply. Militaries are already using wireless technology to connect remote sites. Logistics will be simplified with the ease of tracking with RF technologies. WiMax can also handle Webcams and streaming video which would give commanders eyes on target capability. Just imagine if planes were able to drop preconfigured self deploying WiMax antennas in strategic areas giving troops real time battlefield Intel. Armed with wireless cameras, drones and a GPS one soldier would truly be an Army of One.
As WiMax is deployed in more areas , theory life capabilities of WiMax will come to light. The WiMax and Wi-Fi are Think of a WiMax network as an with out with providing your internet access your businessl home. Wi-Fi will be used within in your LAN future.
8. DEPLOYMENT OF WiMAX Today, last mile connections are typically made through cable, DSL (Digital subscriber Line) ,fiber optic connections and even standard phone lines. The ability to provide these connections wirelessly ,without laying wire or cable in the ground, greatly lowers the cost to provide these services. Intel sees WiMAX deploying in three phases: the first phase of WiMAX technology (based on IEEE 802.16d) will provide fixed wireless connections via out door antennas in the first half of 2005. Outdoor fixed wireless can be used for high-throughput enterprise connections (T1/E1 class services), hotspot and cellular network backhaul, and premium residential services. In the second half of 2005, WiMAX wi". be available for indoor installation, with the smaller antennas similar to a Wi-Fi access pOint today. In this fixed indoor model, WiMAX will be available for use in wide consumer residential broadband deployments, as these devices become "user instal/able", lowering installation costs for carriers. By 2006, the technology wil/ be integrated into mobile computers to support roaming between WiMAX service areas.
9. APPLICATIONS The 802.16 standard will help the industry provide solutions across multiple broadband segments: 1. Cellular back-haul: -Internet backbone providers in the U.S. are requires leasing lines to third -party service providers, an arrangement that has tended to make wired backhaul relatively affordable. The result is that only about 20% of cellular towers are backhauled wirelessly in the U.S. In Europe, where it is less common for local exchange carriers to lease their lines to competitive thirdparties, service providers need affordable alternatives. Subsequently, wireless backhaul is used in approximately 80 percent of European cellular towers. With the potential removal of the leasing requirement by the FCC, U.S. cellular service providers ~ill also look to wireless backhaul as a more cost-effective alternative. The robust bandwidth of 802.16a technology makes it an excellent choice for back-haul for commercial enterprises such as hotspots as well as point-to-point back-haul applications. 2. Broadband on-demand: -Last-mile broadband wireless access can help to accelerate the deployment of 802.11 hotspots and home/small office wireless LANs, especially in those areas not served by cable or DSL or in areas where the local telephone company may have a long lead time for provisioning broadband service. Broadband Internet connectivity is mission critical for many businesses, to the extent that these organizations may actually relocate to areas where service is available. In today's market, local exchange carriers have been known to take three months or more to provision a T1 line for a business customer, if the service is not already available in the
building. Older buildings in metropolitan areas can present a tangle of wires that can make it difficult to deploy broadband connections to selected business tenants. 802.16a wireless technology enables a service provider to provision service with speed comparable to a wired solution in a matter of days, and at significantly reduced cost. 802.16a technology also enables the service provider to offer instantly configurable "on-demand" high-speed connectivity for temporary events including trade shows that can generate hundreds or thousands of users for 802.11 hotspots. In these applications, operators use 802.16a solutions for backhaul to the core network. Wireless technology makes it possible for the service provider to scale-up or scale-down service levels, literally within seconds of a customer request. "On-demand" connectivity also benefits businesses, such as construction sites, that have sporadic broadband connectivity requirements. Premiulll "on demand" last-mile broadband services represent a significant new profit opportunity for operators. 3. Residential broadband: -Filling gaps in cable and DSL coverage:-Practical limitations prevent cable and DSL technologies from reaching many potential broadband customers. Traditional DSL can only reach about 18000 feet (3 miles) from the central office switch, and this limitation means that many urban and suburban locations may not be served by DSL connections. Cable also has its limitations. Many older cable networks have not been equipped to provide a return channel, and converting these networks to support high-speed broadband can be expensive. The cost of deploying able is also significant, deterrent to the extension of wired broadband service in areas with low subscriber density. The current generation of proprietary wireless systems is relatively expensive for massive deployments because without a standard, few economies of state are possible. This cost inefficiency will all change with the launch of
WiMAX 28 standards based systems based on 802.16. in addition, the range of 802.16a solutions, the absence of line of sight requirement, high bandwidth, and the inherent flexibility and low cost helps to overcome the limitations of traditional wired and proprietary wireless technologies 4. Underserved areas: -Wireless internet technology based on IEEE 802.16 is also a natural choice for underserved rural and outlying areas with low population density. In such areas, local utilities and governments work together with a local wireless internet service provider (WISP) to deliver service. Recent statistics show that there are more than 2500 WISPs who take advantage of license exempt spectrum to serve over 6000 markets in the U.S. On an international basis, most deployments are in license spectrum and are deployed by local exchange carriers who require voice services in addition to high speed data. This is because in these areas the wired infrastructure either does not exist or does not offer the quality to support reliable voice, let alone high-speed data. The term wireless local loop is often used to describe such applications, since it is used as a substitute for traditional copper phone wire in the local loop. 5. Best connected wireless service: -As the number of IEEE 802.11 hotspots proliferates, users will naturally want to be wirelessly connected even when they are outside the range of nearest hotspots. The IEEE 801.16e extension to IEEE 802.16a introduces nomadic capabilities which will allow users to connect to a WISP even when they roam outside their home or business or go to another city that also has a WISP.
10. ADVANTAGES The principle advantage of systems based on 802.16 are multi fold : the ability quickly provision even in areas that are hard to avoidance of steep installation costs: and the ability overcome the physical limitations of traditional wired infrastructure. Providing a wired broadband connection to a currently underserved area through cable or can be a time consuming, expensive process, with the that a surprisingly number of areas in the US and throughput the world do not have access to band connectivity 802.16 technology provides a flexible, cost effective, standards based means of filling existing in broad band and creating new forms of broadband services envisioned in a "wired" world.
11. CONCLUSION The cost and complexity associated with traditional wired cable and telephone infrastructure have resulted in significant broadband coverage gaps in the U.S. and international geographies. Early attempts to use wireless technology to fill these coverage gaps have involved a number of proprietary solutions for wireless broad band access that have fragmented the market without providing significant economies of scale. High speed wireless broadcast technology based on the IEEE 802.16 standard promises to open new, economically viable market opportunities for operators, wireless internet service providers, and equipment manufacturers. The flexibility of wireless technology, combine ed with the high through put, scalability, long range and quality of service features of the IEEE 802.16 standard will help fill the broadband coverage gap and reach millions of new residential and business customers world wide . The WiMAX forum is an industry group focused on creating system.
12. BIBLIOGRAPHY Compnetworking.about.com Â¢ Â¢ Â¢ Â¢ pcworld.com Â¢ wimaxtrends.com Â¢ wimaxworld.com Â¢ businessweek.com Â¢ ericson.com Â¢ standars.ieee.org
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WIMAX.ppt (Size: 550.5 KB / Downloads: 485)
Market Targeted by WiMAX
LOS Vs NLOS Technology
WiMAX Technology Challenge
Next generation of Wi-Fi
WiMAX is a fast-emerging wide-area wireless
WiMAX (Worldwide Interoperability for Microwave
Access) forum is a non-profit corporation formed to
help promote and certify the compatibility and
interoperability of BWA
Demand for Wireless Broadband
persons with disabilities
WiMAX Technology Challenge
WiMAX, more flexibility and security
WiMAX, a very efficient radio solution
WiMAX could bring broadband access into the homes
and businesses of millions of people in rural and
Portable Internet a reality
End-users to enjoy an Always Best Connected
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please read topicideashow-to-wimax--5303 and topicideashow-to-wimax and topicideashow-to-wimax-ieee for getting all technical information about wimax ieee and its presentation
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The Next Frontier BroadBand Wireless
WiMAX is a coined term or acronym meaning Worldwide Interoperability For Microwave Access .
WiMax is a new standard being developed by the IEEE that focuses on solving the problems of point to multipoint broadband outdoor wireless networks.
It has several possible applications, including last mile connectivity for homes and businesses and backhaul for wireless hot spots.
Wimax will offer fixed, nomadic and mobile wireless broadband connectivity without direct line-of-sight access to a base station.
Range - 30-mile (50-km) radius from base station.
Speed - 70 megabits per second
Line-of-sight not needed between user and base station
Frequency bands - 2 to 11 GHz and 10 to 66 GHz (licensed and unlicensed bands)
Defines both the MAC and PHY layers and allows multiple PHY-layer specifications
Different IEEE standards:
A WiMAX 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.
Comparison between WiFi & WiMax:
High data rate (50Mbits/sec or higher) Long range (10 miles or more) Low risk of interference.
Can work without line of sight. Low-cost client radios
Low entry cost for service providers, so lots of competition and wide coverage likely.
Smooth upgrade path from fixed to mobile access Low risk of interference .
Advanced IP-based architecture.
Intel announced that it has begun sending WiMax chipsets to equipment manufacturers, which are planning to ship products to customers.
Data centric devices: notebooks, PDAs, Ultra Mobile PCs
CE devices: games consoles, MP3 players
Voice and voice/data devices: cellular phones, smart phones
Vertical applications devices: CCTV cameras, in-vehicle devices.
The big name corporations have
alreadly comeup with a WiMax base
station and WiMax access point for
Redline communicationâ„¢s Wimax
Growing popularity of Wimax:
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Wimax: The Next Broadband Wireless Revolution
Names : T.Snehalatha.
Class : 4/4 B.Tech (E.C.E).
WiMax is the next step on the road to a wireless world, extending broadband wireless access to new locations and over longer distances. It will also significally reduces the cost of bringing broadband to new areas.
WiMax (worldwide Interoperability for Microwave Access) is the recently approved IEEE 802.16 wireless metropolitan area network (MAN) standard for wireless access. WiMax is the real wireless architecture by which the wireless access range can extended to 49.6Kms compared with Wi-Fi 91mts and Bluetoothâ„¢s 9mts. WiMax 802.16
has a single carrier modulation scheme that operates between 10GHz and 66GHz radio frequency and requires line of sight towers for the connection to work. The new ratified 802.16a extension uses a lower frequency range of 2GHz to 11GHz, and does not require line of sight towers. It also boasts 70Mbps data transfer rate that can support thousands of users.
Wi-Fi Vs WiMax:
Wi-Fi uses a small base station plugged into a high speed (broadband ) connection to link laptops or Internet with in 50mts. Wi-Fi is undoubtedly popular.And is used mainly to provide wireless access inside homes, offices and schools.But few people seem to be prepared to pay much amount for Wi-Fi access in Ëœhotspotsâ„¢ like airports and railway stations.
WiMax is considered as the next step beyond Wi-Fi because it is optimized for broadband operation in a WAN. It already includes numerous advancements like quality of service, enhanced security, higher data rates and uses smart antenna technology which allows better use of the spectrum.
ARCHITECTURE OF WiMax:
The core components of a WiMax system are the subscriber station (SS) and the base station (BS). A BS and one or more SSâ„¢s can form a cell with point to multipoint (P2MP) structure. An 802.16 based system often uses fixed antenna at the subscriber station site. The antenna is mounted on the roof. Provisions such as adaptive antenna systems and sub channel stations are also supported by this system.
A BS typically uses either directional or omni directional antennas. A fixed SS typically uses directional antenna while mobile or portable SS uses an omni directional antenna. Multiple BSâ„¢s can be configured to form a cellular wireless network. The 802.16 standard also can be used in a point to point topology with pairs of directional antennas. This increases the effective range of the system compared to what can be achieved in the P2MP mode.
FUNDAMENTAL TECHNOLOGIES IN 802.16:
OFDM (Orthogonal Frequency Division Multiplexing):
It is fundamental technology in digitital TV. It transmits multiple signals simultaneously across the wireless transmission paths within separate frequencies to avoid interference. It is also supported in the WLAN standard. OFDM will almost certainly become dominant in all wireless technologies.
Many systems in the past decade have involved in the fixed modulation, offering a trade off between higher order modulation for high data rates, but requiring optimal links or more robust lower order that will only operate at low data rates. But 802.16 supports adaptive modulation ,balancing different data rates and link quality, making most efficient use of bandwidth.
FDD AND TDD:
The standard also supports both frequency and time division multiplexing to
enable interoperability with cellular and other wireless system. FDD has been widely deployed in cellular telephony. It requires two channel pairs. One for transmission and other for reception, with some frequency separation between them to migrate self-interference.TDD uses a single channel for both upstream and downstream transmissions, dynamically allocating bandwidth depending on traffic requirements.
POTENTIAL WiMax APPLICATIONS:
The WiMax 802.16 will provide solution to the following multiple broadband segments.
The robust bandwidth of 802.16 technology makes it an excellent choice for backhaul for the commercial enterprises, such as those providing Ëœhotspotsâ„¢,as well as for point â€œto-point backhaul applications.
Broadband to underserved and remote areas:
WiMax is a natural choice for under served rural and outlying areas with a low population density.
Broadband on demand:
It can help to accelerate the deployment of Wi-Fi hotspots especially in those areas not served by cable, in areas where the local telephone company may have a long lead time for providing a broadband service.
Best-connected wireless service:
WiMax has nomadic capabilities, which allow users to connect to WISP even when they roam outside their home or business, or go to another city that also has a WISP.
The main obstacles to long distance wireless communications are limitations on battery power and poor power efficiency. Regulation keeps the power levels low and the range of Wi-Fi signals short, to avoid the overcrowding of airwaves. But advances in DSP chips mean that weak signals can be deciphered, lengthening the distance that is practical for transmission, as well as improving distance and speed potential. Battery improvement is vital to make a WiMax cell phone a practicality.
Nokia is working on battery and handset chip designs towards this end. Intel is increasingly involved in next generation battery and processing power for mobile devices, including digital radios that can intelligently tune in to the most efficient network like Cellular,Wi-Fi,Bluetooth,WiMax.
WiMax backers are also working to sort out problems with service providers who want low-cost systems that support portable devices and roaming. In the development cycle, WiMax is expected to support mobile wireless technology, that is wireless transmissions directly to mobile users. This will be similar in function to the General Packet Radio Service (GPRS).
Intel has now promised WiMax versions of its Centrino chipset for 2004, where as Nokia says it will have battery and other technical issues solved in time to launch a WiMax cell phone in 2005.
With in five years, we expect WiMax to be the dominant technology for wireless networking. By that time it will be fully mobile, as well as providing low-cost, fixed broadband access that will open up regions where internet access has no far not been practical.WiMax will be the most significant technology in making wireless access ubiquitous and, as the free spectrum is opened up, in creating a major shake-up of the traditional shape of the wireless and mobile communications sector.
1) Information Technology magazine (October 2004)
5) IEEE magazines
project report maker|
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please read topicideashow-to-WiMAX--5303 and topicideashow-to-WiMAX for WiMax seminar and presentation report and seminar and presentation presentation and topicideashow-to-wimax-ieee and topicideashow-to-fixed-and-mobile-wimax-seminar and presentation-report
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There have been many news recently about BSNL and Tata setting up WiMAX in India.
WiMAX stands for Worldwide Interoperability for Microwave Access. It is a telecommunications technology providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. It is based on the WirelessMAN (IEEE 802.16) standard.
The current WiMAX revision provides up to 40 Mbps with the IEEE 802.16m update expected offer up to 1 Gbit/s fixed speeds. (WiMAX is based on the IEEE 802.16 standard, also called Broadband Wireless Access). The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard. The forum describes WiMAXas "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL"
WiMAX base station equipment with asector antenna and wireless modem on top
A pre-WiMAX CPE of a 26 km (16 mi) connection mounted 13 metres (43 ft) above the ground .
Comparison with Wi-Fi
Comparisons and confusion between WiMAX and Wi-Fi are frequent because both are related to wireless connectivity and Internet access.
WiMAX is a long range system, covering many kilometers, that uses licensed or unlicensed spectrum to deliver connection to a network, in most cases the internet.
Wi-Fi uses unlicensed spectrum to provide access to a local network.
Wi-Fi is more popular in end user devices.
Wi-Fi runs on the Media Access Control's CSMA/CA protocol, which is connectionless and contention based, whereas WiMAX runs a connection-oriented MAC.
WiMAX and Wi-Fi have quite different quality of service (QoS) mechanisms:
iMAX uses a QoS mechanism based on connections between the base station and the user device. Each connection is based on specific scheduling algorithms.
Wi-Fi uses contention access - all subscriber stations that wish to pass data through a wireless access point (AP) are competing for the AP's attention on a random interrupt basis. This can cause subscriber stations distant from the AP to be repeatedly interrupted by closer stations, greatly reducing their throughput.
Both 802.11 and 802.16 define Peer-to-Peer (P2P) and ad hoc networks, where an end user communicates to users or servers on anotherLocal Area Network (LAN) using its access point or base station.
Wi-Fi and WiMAX are complementary. WiMAX network operators typically provide a WiMAX Subscriber Unit which connects to the metropolitan WiMAX network and provides Wi-Fi within the home or business for local devices (eg, Laptops, Wi-Fi Handsets, smartphones) for connectivity. This enables the user to place the WiMAX Subscriber Unit in the best reception area (such as a window), and still be able to use the WiMAX network from any place within their residence.
Connecting to WiMAX
A WiMAX Gateway which provides VoIP, Ethernet and WiFi connectivity.
A WiMAX USB modem for mobile internet.
There are numerous devices on the market that provide connectivity to a WiMAX network. These are known as the "subscriber unit" (SU).
There is an increasing focus on portable units, this includes handsets (similar to cellular smartphones), PC peripherals (PC Cards or USB dongles), and embedded devices in laptops, which are now available for Wi-Fi services. In addition, there is much emphasis from operators on consumer electronics devices such as Gaming consoles, MP3 players and similar devices. It is notable that WiMAX is more similar to Wi-Fi than to3G cellular technologies.
The WiMAX Forum website provides a list of certified devices. However, this is not a complete list of devices available as certified modules are embedded into laptops, MIDs (Mobile internet devices), and other private labeled devices.
WiMAX gateway devices are available as both indoor and outdoor versions from several manufacturers. Many of the WiMAX gateways that are offered by manufactures such as Zytel, Motorola, and GreenPacket are stand-alone self-install indoor units. Such devices typically sit near the customer's window with the best WiMAX signal, and provide:
A integrated Wi-Fi access point to provide the WiMAX Internet connectivity to multiple devices throughout the home or business.
Ethernet ports should you wish to connect directly to your computer or DVR instead.
One or two PSTN telephone jacks to connect your land-line phone and take advantage of VoIP.
There are a variety of USB dongles on the market which provide connectivity to a WiMAX network. Generally these devices are connected to a notebook or net book whilst on the go. Dongles typically have omnidirectional antennae which are of lower-gain compared to other devices, as such these devices are best used in areas of good coverage.
HTC released the first WiMAX enabled mobile phone, the EVO 4G, March 23, 2010 at the CTIA conference in Las Vegas. According to Sprint, the device will be available Summer 2010 and will be capable of both EV-DO(3G) and WiMax (4G).. A number of WiMAX Mobiles are expected to hit the market in 2010.
The WiMAX Forum is a non profit organization formed to promote the adoption of WiMAX compatible products and services.
A major role for the organization is to certify the interoperability of WiMAX products. Those that pass conformance and interoperability testing achieve the "WiMAX Forum Certified" designation, and can display this mark on their products and marketing materials. Some vendors claim that their equipment is "WiMAX-ready", "WiMAX-compliant", or "pre-WiMAX", if they are not officially WiMAX Forum Certified.
Another role of the WiMAX Forum is to promote the spread of knowledge about WiMAX. In order to do so, it has a certified training program that is currently offered in English and French. It also offers a series of member events and endorses some industry events.
WiMAX Spectrum Owners Alliance
WiSOA was the first global organization composed exclusively of owners of WiMAX spectrum with plans to deploy WiMAX technology in those bands. WiSOA focussed on the regulation, commercialisation, and deployment of WiMAX spectrum in the 2.3–2.5 GHz and the 3.4–3.5 GHz ranges. WiSOA merged with the Wireless Broadband Alliance in April 2008.
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Today, all countries are looking for economic, cost-effective, easy, fast-to-deploy, and high-performance next generation type broadband solutions. Users need broadband services everywhere at affordable prices. WiMAX as globally accepted IMT-2000 Family standard brings a solution. Mobile WiMAX offers the full mobility of cellular networks at true broadband speeds. WiMAX offers a combination of both broadband and mobility. WiMAX enables the quadruple services. Currently there are more than more than 100 commercial WiMAX networks around the world. Intel is developing WiMAX chips for products. The new era of communication, currently employed in some parts of the world, is Worldwide Interoperability for Microwave Access (WIMAX). It is the latest technology which is approved by IEEE 802.16 group, which is a standard for point-to-multipoint wireless networking. Mobile WiMAX overcomes the limitations of the present wireless networks and accommodates the advantages of the system, and can ultimately provide the high speed wireless internet services with low lost at any time and in anyplace. Because Mobile WiMAX is very new technology, the research of Mobile WiMAX management is not studied and concerned deeply.
• make portable Internet a reality by extending public WLAN hotspots to metropolitan area coverage for mobile data-centric service delivery,
• connect enterprises and residential users in urban and suburban environments where access to copper plant is difficult,
• bridge the digital divide by delivering broadband in low-density areas.
Thanks to its innovative technology, the same radio technology will also offer high-speed
data services to all nomadic terminals (laptops, PDAs, etc.) with an optimized trade off between throughput and coverage. WiMAX will also enable end-users to benefit from an "Always Best Connected" experience when accessing their applications via the best
available network, at home, on the pause, or on the move.
WiMAX refers to interoperable implementations of the IEEE 802.16 wireless-networks standard (ratified by the WiMAX Forum), in similarity with Wi-Fi, which refers to interoperable implementations of the IEEE 802.11 Wireless LAN standard (ratified by the Wi-Fi Alliance). The WiMAX Forum certification allows vendors to sell their equipment as WiMAX (Fixed or Mobile) certified, thus ensuring a level of interoperability with other certified products, as long as they fit the same profile.
The IEEE 802.16 standard forms the basis of 'WiMAX' and is sometimes referred to colloquially as "WiMAX", "Fixed WiMAX", "Mobile WiMAX", "802.16d" and "802.16e." Clarification of the formal names are as follow:
• 802.16-2004 is also known as 802.16d, which refers to the working party that has developed that standard. It is sometimes referred to as "Fixed WiMAX," since it has no support for mobility.
• 802.16e-2005, often abbreviated to 802.16e, is an amendment to 802.16-2004. It introduced support for mobility, among other things and is therefore also known as "Mobile WiMAX".
Mobile WiMAX is the WiMAX incarnation that has the most commercial interest to date and is being actively deployed in many countries. Mobile WiMAX is also the basis of future revisions of WiMAX. Wimax make possible the broadband access to conservative cable or DSL lines. The working method of Wimax is little different from Wifi network, because Wifi computer can be connected via LAN card, router, or hotspot, while the connectivity of Wimax network constitutes of two parts in which one is Wimax Tower or booster also known as wimax base station and second is Wimax receiver (Wimax CPE) or Customer Premise Equipment.
Now the question comes to our attention, what is Wimax technology and how wimax technology works and why has it taken so long to appear in the marketplace? 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. The definition according to Wimax technology forum, an organization dedicated to promoting Wimax technology and specifications, According to WiMAX forum "Wimax Technology is a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL. Wimax Technology will provide fixed, nomadic, portable, and, eventually, mobile wireless broadband connectivity without the need for direct line-of-sight to a base station. In a typical cell radius deployment of 3 to 10 kilometers, Wimax Forum Certified systems can be expected to deliver capacity of up to 40 Mbps per channel, for fixed and portable access applications." (WiMax Forum, 2007)
In the Wimax terminology, portable access means you can access Wimax networks from different locations, but not necessarily while moving. Mobile Wimax is accessible while on the move.
2.1 WiMAX Technology (802.16) Overview
The 802.16 standard was first available on April 8, 2002 after two years in development. The Wimax Forum was formed in April of 2001 and established in June of 2001. This order might seem odd, but it's common to shape certification bodies before completing or passing a standard. The Wimax certification will certify that a technology is compliant with Wimax specifications not 802.16. This is because the Wimax Forum created a certification that is compatible with a portion of the 802.16 standard. Wimax certified hardware should be compatible with other Wimax certified hardware, but it is important to remember that Wimax certified hardware not necessarily compatible with 802.16 compliant hardware.
The founding organizations of the Wimax Forum included Wi-LAN, Ensemble, CossSpan, Harris, and Nokia. The OFDM Forum and Fujitsu joined in 2002. In 2003, Aperto, Alvarion, Airspan, Intel, Proxim, and others joined the group. At this time, the forum has over 200 members with representatives from service providers, system manufacturers, chip vendors, and business organizations. The major focus of this group is to provide interoperability between vendors' Wimax hardware. (Tom Carpenter, 2006)
In January 2005, at a Wimax conference called “Wimax: beyond the Hype,” Gordon Antonello clearly stated that
• There are no Wimax networks today.
• There are no Wimax form certified products available today.
• Wimax Forum certified testing will begin later this year in 2005.
• Vendors are shipping pre-Wimax products today.
WiMAX is the next-generation of wireless technology designed to enable pervasive, high-speed mobile Internet access to the widest array of devices including notebook PCs, handsets, smartphones, and consumer electronics such as gaming devices, cameras, camcorders, music players, and more. As the fourth generation (4G) of wireless technology, WiMAX delivers low-cost, open networks and is the first all IP mobile Internet solution enabling efficient and scalable networks for data, video, and voice. As a major driver in the support and development of WiMAX, Intel has designed embedded WiMAX solutions for a variety of mobile devices supporting the future of high-speed broadband on-the-go.
Laying the foundation for broad, cost-effective deployments, Intel is working to easily integrate Intel® WiMAX technology into complex designs and global networks, providing a standards-based foundation for ongoing product innovation.
• Building the mobile Internet with WiMAX
• Evolving WiMAX standards and interoperability
• WiMAX global carriers
Built for the future, Intel® WiMAX technology will allow you to connect in more places, more often, without being restricted to hotspots. When built into notebooks and mobile devices, you'll be able to extend your connected experience beyond Wi-Fi.
A Wimax technology network consists of two major components: a wimax base station and a subscriber station (wimax cpe). Wimax base stations provide connectivity to one or more subscriber stations and are implemented by service providers to provide Internet, voice, video or Wireless Area Network (WAN) link access.
These base stations are similar to Wi-Fi Access Points (APs) as they provide centralized access to back end connected networks. They use different standards than Wi-Fi, however, so the evaluation ends there. While subscriber stations are uniquely designed for 802.16 networks, the reality is that they provide a connection to the network and you can still route internal 802.11 devices through the 802.16 subscriber station for network access.
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WIRELESS means transmitting signals using radio waves as the medium instead of wires.
Characterstics of wireless:
e. Roaming Services
f. New Services
Wireless Wide Area Network (WWAN)
Wireless Local Area Network (WLAN)
Wireless Metropolitan Area Network (WMAN)
Wireless Broadband Access (WBA)
Acronym for Worldwide Interoperability for Microwave Access.
Based on Wireless MAN technology.
A scaleable wireless platform for constructing alternative and complementary broadband networks.
A certification that denotes interoperability of equipment built to the IEEE 802.16 or compatible standard.
What is 802.16a ?
The 802.16a standard for 2-11 GHz is a WMAN technology.
The IEEE 802.16 Working Group develops standards that address two types of usage models:
A fixed usage model (IEEE 802.16-2004).
A portable usage model (IEEE 802.16e).
WiMAX Speed and Range
Initial speed of nearby 40MBPS
Could be deployed in a variety of spectrum bands: 2.3GHz, 2.5GHz, 3.5GHz, and 5.8GHz
WiMAX SALIENT FEATURES
Two types of services:
Very high peak data rates
Adaptive modulation and coding
WiMAX uses OFDM
A WiMAX system consists of two major parts:
A WiMAX base station.
A WiMAX receiver.
CONNECTING TO WiMAX
1. WiMAX gateways
2. WiMAX USBmodem
3. WiMAX Mobiles
Ist mobile - Max 4G by HTC(Nov 12th,2008)
IInd mobile – EVO 4G by HTC(March 23rd ,2010)
The name "WiMAX" was created by the WiMAX FORUM, which was formed in June 2001.
Non profit organisation .
Role is to promote knowledge about WiMax
WiMAX and Wi-Fi Comparison
WiMAX is better than Wi-Fi:
as it satisfy a vareity of needs.
Can provide a wideb area range.
Supports high bandwidth solution.
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New and increasingly advanced data services are driving up wireless traffic, which is being further boosted by growth in voice applications in advanced market segments as the migration from fixed to mobile voice continues. This is already putting pressure on some networks and may be leading to difficulties in maintaining acceptable levels of service to subscribers.
For the past few decades the lower band width applications are growing but the growth of broad band data applications is slow. Hence we require technology which helps in the growth of the broad band data applications. WiMAX is such a technology which helps in point-to-multipoint broadband wireless access with out the need of direct line of sight connectivity with base station.
This paper explains about the WiMAX technology, its additional features in physical layer and MAC layer and the benefits of each feature.
This paper focuses on the major technical comparisons (like QOS and coverage) between WiMAX and other technologies. It also explains about the ability of the WiMAX to provide efficient service in multipath environment.
For the past couple decades, low-bandwidth applications such as downloading ring tones and SMS are experiencing sharp growth, but the growth of broadband data applications such as email and downloading/ uploading files with a laptop computer or PDA has been slow. The demand for broadband access continues to escalate worldwide and lower-bandwidth wire line methods have failed to satisfy the need for higher bandwidth integrated data and voice services. WiMAX is radio technology that promises two-way Internet access at several megabits per second with ranges of several miles. It is believed that the technology can challenge DSL (Digital Subscriber Line) and cable broadband services because it offers similar speeds but is less expensive to set up. The intention for WiMAX is to provide fixed, nomadic, portable and, eventually, Mobile wireless broadband connectivity without the need for Direct line-of-sight with a base station.
III.What is wimax?
WiMAX is an acronym that stands for “Worldwide Interoperability for Microwave Access”. IEEE 802.16 is working group number 16 of IEEE 802, specializing in point-to-multipoint broadband wireless access. It also is known as WiMAX. There are at least four 802.16 standards: 802.16, 802.16a, 802.16-2004 (802.16), and 802.16e.
WiMAX does not conflict with WiFi but actually complements it. WiMAX is a wireless metropolitan area network (MAN) technology that will connect IEEE 802.11 (WiFi) hotspots to the Internet and provide a wireless extension to cable and DSL for last km broadband access. IEEE 802.16 provides up to 50 km of linear service area range and allows user’s connectivity without a direct line of sight to a base station. The technology also provides shared data rates up to 70 Mbit/s.
The portable version of WiMAX, IEEE 802.16 utilizes Orthogonal Frequency Division Multiplexing Access (OFDM/OFDMA) where the spectrum is divided into many sub-carriers. Each sub-carrier then uses QPSK or QAM for modulation. WiMAX standard relies mainly on spectrum in the 2 to 11 GHz range. The WiMAX specification improves upon many of the limitations of the WiFi standard by providing increased bandwidth and stronger encryption
For years, the wildly successful 802.11 x or WiFi wireless LAN technology has been used in BWA applications. When the WLAN technology was examined closely, it was evident that the overall design and feature set available was not well suited for outdoor Broadband wireless access (BWA) applications. WiMAX is suited for both indoor and outdoor BWA; hence it solves the major problem.
In reviewing the standard, the technical details and features that differentiate WiMAX certified equipment from WiFi or other technologies can best be illustrated by focusing on the two layers addressed in the standard, the physical (PHY) and the media access control (MAC) layer design.
III. a) WIMAX PHY Layer
The first version of the 802.16 standard released addressed Line-of-Sight (LOS) environments at high frequency bands operating in the 10-66 GHz range, whereas the recently adopted amendment, the 802.16a standard, is designed for systems operating in bands between 2 GHz and 11 GHz. The significant difference between these two frequency bands lies in the ability to support Non-Line -of-Sight (NLOS) operation in the lower frequencies, something that is not possible in higher bands. Consequently, the 802.16a amendment to the standard opened up the opportunity for major changes to the PHY layer specifications specifically to address the needs of the 2-11 GHz bands. This is achieved through the introduction of three new PHY-layer specifications (a new Single Carrier PHY, a 256 point FFT OFDM PHY, and a 2048 point FFT OFDMA PHY);
Some of the other PHY layer features of 802.16a that are instrumental in giving this technology the power to deliver robust performance in a broad range of channel environments are; flexible channel widths, adaptive burst profiles, forward error correction with concatenated Reed-Solomon and convolutional encoding, optional AAS (advanced antenna systems) to improve range/capacity, DFS (dynamic frequency selection)-which helps in minimizing interference, and STC (space-time coding) to enhance performance in fading environments through spatial diversity. Table 1 gives a high level overview of some of the PHY layer features of the IEEE 802.16a standard.
b) IEEE 802.16a MAC Layer
The 802.16a standard uses a slotted TDMA protocol scheduled by the base station to allocate capacity to subscribers in a point-to-multipoint network topology. By tarting with a TDMA approach with intelligent scheduling, WiMAX systems will be able to deliver not only high speed data with SLAs, but latency sensitive services such as voice and video or database access are also supported. The standard delivers QoS beyond mere prioritization, a technique that is very limited in effectiveness as traffic load and the number of subscriber’s increases. The MAC layer in WiMAX certified systems has also been designed to address the harsh physical layer environment where interference, fast fading and other phenomena are prevalent in outdoor operation.
At the PHY layer the standard supports flexible RF channel bandwidths and reuse of these channels (frequency reuse) as a way to increase cell capacity as the network grows. The standard also specifies support for automatic transmit power control and channel quality measurements as additional PHY layer tools to support cell planning/deployment and efficient spectrum use. Operators can re-allocate spectrum through sectorization and cell splitting as the number of subscribers grows.
In the MAC layer, the CSMA/CA foundation of 802.11, basically a wireless Ethernet protocol, scales about as well as does Ethernet. That is to say - poorly. Just as in an Ethernet LAN, more users results in a geometric reduction of throughput, so does the CSMA/CA MAC for WLANs. In contrast the MAC layer in the 802.16 standard has been designed to scale from one up to 100's of users within one RF channel, a feat the 802.11 MAC was never designed for and is incapable of supporting.
The BWA standard is designed for optimal performance in all types of propagation environments, including LOS, near LOS and NLOS environments, and delivers reliable robust performance even in cases where extreme link pathologies have been introduced. The robust OFDM waveform supports high spectral efficiency over ranges from 2 to 40 kilometers with up to 70 Mbps in a single RF channel. Advanced topologies (mesh networks) and antenna techniques (beam-forming, STC, antenna diversity) can be employed to improve coverage even further. These advanced techniques can also be used to increase spectral efficiency, capacity, reuse, and average and peak throughput per RF channel. In addition, not all OFDM is the same. The OFDM designed for BWA has in it the ability to support longer range transmissions and the multi-path or reflections encountered. In contrast, WLANs and 802.11 systems have at their core either a basic CDMA approach or use OFDM with a much different design, and have as a requirement low power consumption limiting the range. OFDM in the WLAN was created with the vision of the systems covering tens and maybe a few hundreds of meters versus 802.16 which is designed for higher power and an OFDM approach that supports deployments in the tens of kilometers.
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In recent years, Broadband technology has rapidly become an established, global commodity required by a high percentage of the population. The demand has risen rapidly, with a worldwide installed base of 57 million lines in 2002 rising to an estimated 80 million lines by the end of 2003. This healthy growth curve is expected to continue steadily over the next few years and reach the 200 million mark by 2006. DSL operators, who initially focused their deployments in densely-populated urban and metropolitan areas, are now challenged to provide broadband services in suburban and rural areas where new markets are quickly taking root. Governments are prioritizing broadband as a key political objective for all citizens to overcome the “broadband gap” also known as “digital divide”.
Wireless DSL (WDSL) offers an effective, complementary solution to wireline DSL, allowing DSL operators to provide broadband service to additional areas and populations that would otherwise find themselves outside the broadband loop. Government regulatory bodies are realizing the inherent worth in wireless technologies as a means for solving digital-divide challenges in the last mile and have accordingly initiated a deregulation process in recent years for both licensed and unlicensed bands to support this application. Recent technological advancements and the formation of a global standard and interoperability forum - WiMAX, set the stage for WDSL to take a significant role in the broadband market. Revenues from services delivered via Broadband Wireless Access have already reached $323 million and are expected to jump to $1.75 billion.
There are several ways to get a fast Internet connection to the middle of nowhere. Until not too long ago, the only answer would have been "cable" — that is, laying lines. Cable TV companies, who would be the ones to do this, had been weighing the costs and benefits. However this would have taken years for the investment to pay off. So while cable companies might be leading the market for broadband access to most people (of the 41% of Americans who have high-speed Internet access, almost two-thirds get it from their cable company), they don't do as well to rural areas. And governments that try to require cable companies to lay the wires find themselves battling to force the companies to take new customers.
Would DSL be a means of achieving this requisite of broadband and bridging the digital divide?
The lines are already there, but the equipment wasn't always the latest and greatest, even then. Sending voice was not a matter of big concern, but upgrading the system to handle DSL would mean upgrading the central offices that would have to handle the data coming from all those farms.
The most rattling affair is that there are plenty of places in cities that can't handle DSL, let alone the country side. Despite this, we’ll still read about new project and implimentations to lay cable out to smaller communities, either by phone companies, cable companies, or someone else. Is this a waste of money? Probably because cables are on their way out. Another way to get broadband to rural communities is the way many folks get their TV: satellite, which offers download speeds of about 500 Kbps —faster than a modem, but at best half as fast as DSL — through a satellite dish. But you really, really have to want it. The system costs $600 to start, then $60 a month by the services provided by DIRECWAY in the US.
There are other wireless ways to get broadband access.
MCI ("Microwave Communications Inc.") was originally formed to compete with AT & T by using microwave towers to transmit voice signals across the US. Unlike a radio (or a Wi-Fi connection), those towers send the signal in a straight line —unidirectional instead of omni directional. That's sometimes called fixed wireless or point-to-point wireless. One popular standard for this is called LMDS: local multipoint distribution system. Two buildings up to several miles apart would have microwave antennas pointing at each other. One (in, say, the urban area) would be connected to the Internet in the usual way, via some kind of wire; the other (in the rural area you want to connect) would send and receive data over the microwave link, and then be connected to homes and farms via cables. Those cables would be much shorter and less expensive, with the bulk of the transmission being done through the ether.
WiMax delivers broadband to a large area via towers, just like cell phones. This enables your laptop to have high-speed access in any of the hot spots. Instead of yet another cable coming to your home, there would be yet another antenna on the cell-phone tower. This is definitely a point towards broadband service in rural areas. First get the signal to the area, either with a single cable (instead of one to each user) or via a point-to-point wireless system. Then put up a tower or two, and the whole area is online. This saves the trouble of digging lots of trenches, or of putting up wires that are prone to storm damage.
However there is one promising technology that still uses cables to deliver a broadband signal to, well, wherever. It doesn't require laying any new wires (like cable Internet), and it doesn't require overhauling a lot of existing systems (like DSL).It's BPL: (broadband over power lines). As the name suggests, it piggybacks a high speed data signal on those ubiquitous power lines. Those aren't the low-voltage ones that come to your house, but the medium-voltages ones that travel from neighborhood to neighborhood. The signal, like those power lines, can travel a long way thanks to "regenerators" that not only pass the data along, but clean the signal so it doesn't degrade over distance. That means the signal can travel as long as the lines do. Those regenerators can also include Wi-Fi antennas, so if you space them properly they can be placed near homes and farms and whatnot. You can also connect a cable to one to take the signal to the door if you don't feel like going the W-Fi way.
However there have been certain hiccups in the case of BPL. Unlike some early (and ongoing) attempts to do Internet through power lines, BPL doesn't go into individual homes. That's because in order to do so, the signal would have to make its way through a transformer and through a circuit-breaker box, both of which play havoc with it. The result is that the data get through, but much more slowly than leaving the power line before the transformer.
Combine BPL with Wi-Fi, WiMAX, or even (short) cables, and we have an inexpensive way to get the power of the Internet down on the farm using the power of power.
WiMAX is revolutionizing the broadband wireless world, enabling the formation of a global mass-market wireless industry. Putting the WiMAX revolution in the bigger context of the broadband industry, this paper portrays the recent acceleration stage of the Broadband Wireless Access market, determined by the need for broadband connectivity and by the following drivers:
A) The worldwide deregulation process
B) The standardization progression; and
C) Revolutionary wireless technology.
Creating new opportunities on the horizon
A major driver impacting the broadband wireless explosion is the advent of global telecom deregulation, opening up the telecommunications/Internet access industries to a host of new players. As more and more countries enable carriers and service providers to operate in a variety of frequencies, new and lucrative broadband access markets are springing up everywhere. Wireless technology requires the use of frequencies contained within a given spectrum to transfer voice and data. Governments allocate a specific range of that spectrum to incumbent and competitive carriers, as well as cellular operators, ISPs, and other service providers, enabling them to launch a variety of broadband initiatives based exclusively on wireless networking solutions.
There are two main types of spectrum allocation: licensed and unlicensed.
Licensed frequencies are typically awarded through an auction or “beauty contest” to those who present the soundest business plans to the regulatory authorities overseeing the process.
Unlicensed frequencies allow multiple service providers to utilize the same section of the spectrum and compete with each other for customers.
WiMAX - Worldwide Interoperability for Microwave Access
The WiMAX Forum is a non-profit trade organization, founded in April 2002 by leading vendors of wireless access equipment and telecommunications components. The Forum's mission is to lay the groundwork for an industry-wide acceptance and implementation of the IEEE 802.16 and ETSI HiperMAN standard, covering the 2-11 GHz bands for Wireless Metropolitan Area Networks (Wireless
MAN). The Forum hopes to jump-start this crucial industry by establishing rigorous definitions for testing and certifying products for interoperability compliance. The issuing of a “WiMAX-Certified” label will serve as a seal of approval that a particular vendor’s system or component fully corresponds to the technological specifications set forth by the new Wireless MAN protocol.
In order to ensure the success of wireless technology as a stable, viable and cost effective alternative for delivering broadband access services in the last mile, the introduction of industry standards is essential. The companies that have already joined the WiMAX Forum represent over 75% of revenues in the global
BWA market. Moreover, membership of the WiMAX Forum is not limited to industry leading BWA providers; numerous multinational enterprises like Intel and Fujitsu have also joined the WiMAX Forum. The Forum represents a cross-industry group of valued partners, including chip set manufacturers, component makers and service providers. All of these organizations recognize the long-term benefits of working with standardized, interoperable equipment and are committed to the design, development and implementation of WiMAX-compliant solutions.
OVERVIEW OF THE 802.16 IEEE STANDARDS
The 802.16 standard, amended by the IEEE to cover frequency bands in the range between 2 GHz and 11 GHz, specifies a metropolitan area networking protocol that will enable a wireless alternative for cable, DSL and T1 level services for last mile broadband access, as well as providing backhaul for 801.11 hotspots.
The new 802.16a standard specifies a protocol that among other things supports low latency applications such as voice and video, provides broadband connectivity without requiring a direct line of sight between subscriber terminals and the base station (BTS) and will support hundreds if not thousands of subscribers from a single BTS. The standard will help accelerate the introduction of wireless broadband equipment into the marketplace, speeding up last-mile broadband deployment worldwide by enabling service providers to increase system performance and reliability while reducing their equipment costs and investment risks.
However it has been shown repeatedly that adoption of a standard does not always lead to adoption by the intended market. For a market to be truly enabled, products must be certified that they do adhere to the standard first, and once certified it must also be shown that they interoperate. Interoperability means the end user can buy the brand they like, with the features they want, and know it will work with all other like certified products.
For the Broadband Wireless Access (BWA) market and its 802.16 standard,
this role is played by the Worldwide Microwave Interoperability Forum or WiMAX. WiMAX is instrumental in removing the barrier in adopting the standard by assuring demonstrable interoperability between system components developed by OEMs. WiMAX will develop conformance and interoperability test plans, select certification labs and will host interoperability events for IEEE 802.16 equipment
Satisfying the growing demand for BWA in underserved markets has been a continuing challenge for service providers, due to the absence of a truly global standard. A standard that would enable companies to build systems that will effectively reach underserved business and residential markets in a manner that supports infrastructure build outs comparable to cable, DSL, and fiber. For years, the wildly successful 802.11x or WiFi wireless LAN technology has been used in BWA applications along with a host of proprietary based solutions. When the
WLAN technology was examined closely, it was evident that the overall design and feature set available was not well suited for outdoor BWA applications. It could be done, it is being done,but with limited capacity in terms of bandwidth and subscribers, range and a host of other issues made it clear this approach while a great fit for indoor WLAN was a poor fit for outdoor BWA.
WiMAX and the IEEE 802.16a PHY Layer
The first version of the 802.16 standard released addressed Line-of-Sight (LOS) environments at high frequency bands operating in the 10-66 GHz range, whereas the recently adopted amendment, the 802.16a standard, is designed for systems operating in bands between 2 GHz and 11 GHz. The significant difference between these two frequency bands lies in the ability to support Non-Line-of-Sight (NLOS) operation in the lower frequencies, something that is not possible in
higher bands. Consequently, the 802.16a amendment to the standard opened up the opportunity for major changes to the PHY layer specifications specifically to address the needs of the 2-11 GHz bands. This is achieved through the introduction of three new PHY-layer specifications (a new Single Carrier PHY, a 256 point FFT OFDM PHY, and a 2048 point FFT OFDMA PHY);major changes to the PHY layer specification as compared to the upper frequency, as well as significant MAC-layer enhancements. Although multiple PHYs are specified as in the 802.11 suite of standards (few recall that infrared and frequency hopping were and are part of the base 802.11 standard), the WiMAX Forum has determined that
the first interoperable test plans and eventual certification will support the 256 point FFT OFDM PHY (which is common between 802.16a and ETSI HiperMAN), with the others to be developed as the market requires.
The OFDM signaling format was selected in preference to competing formats such as CDMA due to its ability to support NLOS performance while maintaining a high level of spectral efficiency maximizing the use of available spectrum. In the case of CDMA (prevalent in 2G and 3G standards), the RF bandwidth must be much larger than the data throughput, in order to maintain processing gain adequate to overcome interference. This is clearly impractical for broadband wireless below 11 GHz, since for example, data rates up to 70 Mbps would require RF bandwidths exceeding 200 MHz to deliver comparable processing gains and NLOS performance.
Some of the other PHY layer features of 802.16a that are instrumental in giving this technology the power to deliver robust performance in a broad range of channel environments are; flexible channel widths, adaptive burst profiles, forward error correction with concatenated Reed-Solomon and convolutional encoding, optional AAS (advanced antenna systems) to improve range/capacity, DFS (dynamic frequency selection)-which helps in minimizing interference, and STC (space-time coding) to enhance performance in fading environments through spatial diversity.
Table 1 gives a high level overview of some of the PHY layer features of the IEEE 802.16a standard.
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IEEE 802.16 - Wireless MANs
Wireless PANs (Bluetooth – IEEE 802.15)
– very low range
– wireless connection to printers etc
Wireless LANs (WiFi – IEEE 802.11)
– infrastructure as well as ad-hoc networks possible
– home/office networking
– Multihop Ad hoc Networks
– useful when infrastructure not available, impractical, or expensive
– military applications, emergencies
Goal: Provide high-speed Internet access to home and business subscribers, without wires.
Base stations (BS) and subscriber stations (SS)
Centralized access control to prevents collisions
Supports applications with different QoS requirements
WiMAX is a subset of IEEE 802.16 standard
IEEE 802.16 standards
802.16.1 (10-66 GHz, line-of-sight, up to 134Mbit/s)
802.16.2 (minimizing interference between coexisting WMANs)
802.16a (2-11 Ghz, Mesh, non-line-of-sight)
802.16b (5-6 Ghz)
802.16c (detailed system profiles)
P802.16e (Mobile Wireless MAN)
Allows use of directional antennas
Allows use of two different duplexing schemes:
– Frequency Division Duplexing (FDD)
– Time Division Duplexing (TDD)
Support for both full and half duplex stations
Adaptive Data Burst profiles
– Transmission parameters (e.g. Modulation, FEC) can be modified on a frame-by-frame basis for each SS
– Profiles are identified by ”Interval Usage Code”
Time Division Duplexing (TDD)
Media Acces Control (MAC)
– Connection ID (CID), Service Flows
– Channel access: decided by BS
– Defines uplink channel access
– Defines uplink data burst profiles
– Defines downlink data burst profiles
– UL-MAP and DL-MAP are both transmitted in the beginning of each downlink subframe
TDD Downlink subframe
Initial Maintenance opportunities
– Ranging - to determine network delay and to request power or profile changes
– Collisions may occur in this interval
– Request opportunities
– SSs request bandwith in response to polling from BS
– Collisions may occur in this interval
– Data grants period
– SSs transmit data bursts in the intervals granted by the BS
– Transition gaps between data intervals for synchronization
– Bandwidth request
SSs may request bandwidth in 3 ways:
– Use the ”contention request opportunities” interval upon being polled by the BS
– Send a standalone MAC message called ”BW request” in an allready granted slot
– Piggyback a BW request message on a data packet
BS grants/allocates bandwidth in one of two modes:
– Grant Per Subscriber Station (GPSS)
– Grant Per Connection (GPC)
Decision based on requested bandwidth and QoS requirements vs available resources
Grants are notified through the UL-MAP
Bandwidth Request-Grant Protocol
Unsolicited Grant Service (UGS)
– Real-time, periodic fixed size packets (e.g. VoIP)
– No periodic bandwith requests required
Real-Time Polling Service (rtPS)
– Real-time, periodic variable sizes packets (e.g MPEG)
– BS issues periodic unicast polls
Non-Real-Time Polling Service (nrtPS)
– Variable sized packets with loose delay requirements (FTP)
– BS issues unicast polls regularly (not necessarily periodic)
– Can also use contention requests and piggybacking
Best Effort Service
– Never polled individually
– Can use contention requests and piggybacking
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Abstract. The term WIMAX (Worldwide Interoperability for Microwave Access) has become synonymous with the IEEE 802.16 Wireless Metropolitan Area Network (MAN) air interface standard. Filling the gap between Wireless LANs and wide area networks, WIMAX-compliant systems will provide a cost-effective fixed wireless alternative to conventional wire-line DSL and cable in areas where those technologies are readily available. The WIMAX technology can provide a cost-effective broadband access solution in areas beyond the reach of DSL and cable.
The ongoing evolution of IEEE 802.16 will expand the standard to address mobile applications thus enabling broadband access directly to WIMAX-enabled portable devices ranging from smart phones and PDAs to notebook and laptop computers. Thus WIMAX is going to be a revolution in the world of communications. First of all, it will suppose an explosion of the wireless data networks, being not a substitute but a complement to Wi-Fi, and if technology advances enough to get a good intercity wireless link, these networks could be comparable to the internet. It will mean also revolution in the world of mobile communications, being a serious competitor with UMTS. WIMAX Forum Certified products will extend the range of Wi-Fi networks from the local area to the metropolitan area and beyond. These products will be based upon the 802.16 standard and will support distances of up to 50 kilometers – far longer distances than supported by Wi-Fi products.
Word Count. 228
Keywords. IEEE 802.16, MAN, NLOS, PDA, UMTS, Wi-Fi.
“A new metropolitan-area wireless standard will change the economics of Internet access—again.”
It’s hard to buy a laptop computer today that doesn’t come with a Wi-Fi chip: a built-in radio that lets users surf the Web wirelessly from the boardroom, the bedroom, or the coffee bar. People love Wi-Fi because a single base station - a box with a wired connection to the Internet, such as a DSL, cable, or T1 line can broadcast to multiple users across distances as great as 100 meters indoors and 400 meters out-doors. But there’s a new technology on the way that will make Wi-Fi look feeble. IT’S CALLED WiMAX.
AND WiMAX provides wireless broadband Internet connections at speeds similar to Wi-Fi - but over distances of up to 50 kilometers from a central tower. “Metropolitan area” wireless networking at broadband speeds isn’t new, but the specialized equipment that receives the broadband signals has typically been too expensive for everyone but large businesses. Now that U.S. computing and communications firms are gradually reaching consensus on the details of the WiMAX standard, however, those prices could come down significantly. Industry agreement on details such as how to encrypt WiMAX signals, which frequencies to use, and how to provide multiple users with access to those frequencies will finally allow companies like Intel to manufacture mass quantities of WiMAX-enabled chips for use in broadband wireless equipment. And that’s expected to eventually bring WiMAX receivers into the $50 to $100 price range of today’s DSL and cable modems, meaning that millions of users could eventually drop their current Internet
Service Providers - often local phone or cable companies - and simply access the Internet over rooftop antennas at the other end of town.
WHAT IS WIMAX?
WiMAX is a wireless metropolitan-area network technology that provides interoperable broadband wireless connectivity to fixed, portable and nomadic users. It provides up to 50- kilometers of service area, allows users to get broadband connectivity without the need of direct line-of-sight to the base station, and provides total data rates up to 75 Mbps— enough bandwidth to simultaneously support hundreds of businesses and homes with a single base station. This white paper discusses wireless metro-access technologies: Wi-Fi with high gain antennas, Wi-Fi meshed networks and WiMAX. It explores how the technologies differ and how they can be combined to provide a total last-mile access solution now and in the future.
WiMAX is a standard-based technology which will serve as a wireless extension or alternative to cable and DSL for broadband access. Particularly for end users in rural, sparsely populated areas or in areas where laying cable is difficult or uneconomical, WiMAX will provide a new broadband access path to the internet.
Typical modified IEEE 802.11 network topologies associated with last-mile and hot-zone coverage use either directional antennas or a mesh-network topology. Wi-Fi provides the
certification for IEEE 802.11 client-to-access point (AP) communications. However, implementations of AP-to-AP and AP-to-service providers (that is, backhaul applications) that are typically needed for wireless last-mile and hot-zone coverage are still proprietary, thus providing little or no interoperability. Because the IEEE 802.11 standards were designed for unwiring the local area network (LAN), metro-access applications are facing the following challenges:
• Non-standard wireless inter-AP communication. Today, wireless links used to connect 802.11 APs for inter-AP communication in mesh networking are vendor-specific. The proposed IEEE 802.11s standard, estimated to be ratified in 2007, will standardize Wi-Fi mesh networking.
• Providing quality of service (QoS). QoS refers to the ability of the network to provide better service to selected network traffic over various technologies. The goal of QoS technologies is to provide priority (including dedicated bandwidth to control jitter and latency) that is required by some real-time and interactive traffic, while making sure that in so doing the traffic on the other paths does not fail. In general, unlicensed bands can be subject to QoS issues because deployment is open to anyone.
• Expensive backhaul costs. Backhaul refers both to the connection from the AP back to the provider and to the connection from the provider to the core network.
Despite the challenges, wireless metro-access solutions are continuously sought after for the following reasons:
• Wireless metro-access solutions available today, such as mesh networking implementations, are more cost-effective and flexible than their wired counterparts.
• These solutions provide a standards-based connection from AP-to-mobile users for hot-zone coverage.
• Local governments can provide free access for businesses or emergency services (such as police and fire fighters).
• Educational institutions can broaden learning through online collaboration between students and faculty on and off campus.
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WiMAX (Worldwide Interoperability for Microwave Access) is a telecommunications protocol that provides fixed and mobile Internet access. The current WiMAX revision provides up to 40 Mbit/s with the IEEE 802.16m update expected to offer up to 1 Gbit/s fixed speeds. The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard. The forum describes WiMAX  as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL (Digital Subcarrier Line)".
The IEEE wireless standard has a range of up to 30 miles, and can deliver broadband at around 75 megabits per second. This is theoretically, 20 times faster than a commercially available wireless broadband.
Fig1.1 Wimax Architecture 
It is a broadband FWA(Fixed Wireless Access)system with the goal of delivering ”last mile” fixed, nomadic, portable and mobile wireless connections on a metropolitan scale. It has been designed for point to multipoint operation, between one base station (BS) and several subscriber stations (SS). It provides specifications for both fixed Line of sight (LOS) communication in the range of 10-66 GHz (IEEE 802.16c), and fixed, portable, non-LOS communication in the range of 2-11 GHz (IEEE 802.16a & IEEE 802.16d), non-LOS communication in the range of 2-6 GHz (IEEE 802.16e). WI -MAX is not truly new; rather, it is unique because it was a bottom-up design to deliver maximum throughput to maximum distance while offering 99.999 percent reliability. The IEEE 802.16 standard specifies the Physical (PHY) Layer and Medium Access Control (MAC) layer for BWA (Broadband Wireless Association) within MAN (Metropolitan Area Network).
1.1 USES OF WIMAX
• Connecting Wi-Fi hotspots to the Internet.
• Providing a wireless alternative to cable and DSL (Digital Subcarrier Line) for "last mile" broadband access.
• Providing data and telecommunications services.
• Providing a source of Internet connectivity as part of a business continuity plan.
• Providing portable connectivity.
• Providing hassle free, reliable & hi-speed broadband access.
1.2 DIFFERENCE OF WI-IF & WI-MAX
Wifi(Wireless Fidelity) is used for developing wireless LAN( Local Area Network) to access high speed internet or access just a network for file sharing and software services. Whereas Wi-Max is quite latest technology and it can do far more than just developing wireless networks for high speed internet. It is also refer as Wireless broadband access, which can transfer not only data, but voice data, video data etc and at much higher rates.
Wi-Fi is capably for short range data transfer, which can be within hundred of meters range using non licensed spectrum to access network. Wi-Fi is mostly connected to network in certain area which may not be connected to internet; it can be used for file sharing only. Whereas Wi-Max is designed for long distance coverage and it covers distance in kilometers, it uses licensed spectrum and unlicensed also in some case. WiMax delivers point-to-point connection to the internet from service provide to as user. In WiMax there are multiple standards of 802.16 a, b etc, so they are used for different types of access from mobile connectivity to fixed location connections.
WiFi has introduced a quality of service similar to fixed Ethernet, where packets are priorities on their tags. This shows that quality of service (QoS) is relative to packet flow. Whereas WiMax uses technology based on setting up connection between end users’ device and base station. Special algorithm is scheduled for specific connection. This shows that Quality of Services (QoS) parameters can be guaranteed for each flow.
WiFi is deployed much more than WiMax because of its ease of installation and cost effectiveness. It is easily deployed within the building or room for providing internet access by third party internet service providers. Many public places, hotels, coffee shops have installed Wi-fi access points providing high speed internet to their customers.
RELATIONSHIP WITH OTHER WIRELESS
2.1 WIFI (Wireless Fidelity) TECHNOLOGY (IEEE 802.11 Standards)
The name of a popular wireless networking technology that uses radio waves to provide wireless high-speed Internet and network connections. The Wi-Fi Alliance, the organization that owns the Wi-Fi (registered trademark) term specifically defines Wi-Fi as any "wireless local area network (WLAN) products that are based on the Institute of Electrical and Electronics Engineers' (IEEE) 802.11 standards." Wi-Fi is commonly called as wireless LAN, it is one of those networks in which high frequency radio waves are required for transmission of data from one place to another. Wi-Fi operates on several hundred feet between two places of data transmission. This technology only works on high frequency radio signals. Otherwise, it will not work properly. Nowadays this technology is used as office or home network and in many electronic devices. Wireless LAN or Wi-Fi is divided into three main parts on which its whole working depends and all of its applications also depend on these parts i.e. infrastructure mode, ad hoc network and mixed network.
2.2 ZIGBEE TECHNOLOGY (IEEE 802.15.4 Standard)
A type of low cost, low power and wireless technology which is used for the different purposes at ultra low power is known as Zig bee technology. Low power radios on the basis of standard personal wireless networking are used by a protocol to enhance the technology. It offers excellent wireless control path network. It was not proposed or designed for the excellent or high speed data transfer rate applications. But it was designed for working on excellent long battery timings at low cost and also at ultra low power consumption. It is an ideal technology which operates at low power and low cost and used for wireless monitoring and control. Zig-Bee was developed for addressing the market demand for a standards based, cost-effective solution for wireless networking which supports low consumption of power low data rates, reliability and security. Zig-Bee is the only technology based on standards, which address the special needs of most of the remote monitoring and sensory and control network applications. If you want a solution for remote control and wireless monitoring, then Zig-Bee is the best answer to you.
2.3 BENEFITS OF WIMAX
• Long Range: The most significant benefit of WiMAX compared to existing wireless technologies is the range. WiMAX has a communication range of up to 30 miles. This can cover over 2800 square miles
• Low Cost: Base stations will cost under $20,000 but will still provide customers with T1-class connections
• Wireless: By using a WiMAX system, companies/ residents no longer have to rip up buildings or streets or lay down expensive cables.
• High Bandwidth: WiMAX can provide shared data rates of up to 70 Mb/s. This is enough bandwidth to support more than 60 businesses at once with T1-type connectivity. It can also support over a thousand homes at 1 Mb/s DSL-level connectivity. Also, there will be a reduction in latency for all WiMAX communications.
• Built-in Qos
• High performance
• Smart antenna support
• The single station of Wimax can operate and provide coverage for hundred of users at a time and manage sending and receiving of data at very high speed with full of network security.
• The High speed of connectivity over long distance and high speed voice makes it more demanded in hardly populated areas plus compacted areas.
• Wimax Technology perform a variety of task at a time such as offering high speed internet, providing telephone service, transformation of data, video streaming, voice application etc.
• Data rate as high as 280Mbps and distances of 30 miles are possible.
• No FCC radio licensing is required.
• Line of side (LOS) is required for long distance (5-30 mile) connections.
• Heavy rains can disrupt the service.
• The Wimax network has lack of quality service because there are hundreds of people trying to get access at the same tower so due to heavy traffic it is very hard to maintain high quality.
• Like other network Bandwidth is collective amongst clients in a specified zone. But if there are a lot of users in one area the speed decreases which may be 2 to 10 Mbps of shared bandwidth.
• The most disadvantage of Wimax is its installation and operational cost. Due to heavy structure, tower, antennas etc makes the Wimax network collectively high cost network.
• Wimax network is very heavy in structure therefore need much electrical support for running the overall network.
• The data rate of Wimax as compared to other network such as fiber optics, satellite, cables etc are very slow.