ABSTRACT!!!!
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.
It’s hard to [censored] 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
Service Providers - often local phone or cable companies - and simply access the Internet over rooftop antennas at the other end of town.
ABOUT WIMAX
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 the moniker used for the IEEE 802.16 wireless interface specifications promoted by the industry trade organization ‘Forum for Worldwide Interoperability for Microwave Access’. Members of the WiMAX Forum™ 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 owner’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.
Abstract:
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.
1. INDRODUCTION
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 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.
WiMAX r
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 LAN. 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>
There are two types of access points: • Dedicated hardware access points such as Lucent's Wave LAN, Apple's Airport Base Station or Web Gear's Aviator PRO. • Software access points which run on a computer equipped with a wireless network interface path as used in ad-hoc or peer to peer wireless network.
IEEE WIRELESS COMMUNICATIONS STANDARDS 3.1 802.11
Working Group for Wireless Local Area Networks is standards 11 specify 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. Wi-Fi" 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 that led to IEEE 802.16a was approved in march 2000. The 802.16a project 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 [3]. ( " Recommended Practice for Coexistence of Fixed Broadband Wireless Access Systems") to address 1 0-66 GHz coexistence and, through the amendment project 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 burst 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 transmechanism. 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 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 projectB02.16a.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 interoperability Design 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 accesses 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.
