a survey on wimax

(IJCSIS) International Journal of Computer Science and Information Security, Vol. 8, No. 2, 2010 A Survey on WiMAX Mohsen Gerami The Faculty of Applied Science of Post and Communications Danesh Blv, Jenah Ave, Azadi Sqr, Tehran, Iran. Postal code: 1391637111 e-mail: [email protected] Abstract — This paper describes an overview of WiMAX. The paper outlines fundamental architectural components for WiMAX and explains WiMAX Secur ity Issues. Furthermore various 802.16 standards, IEEE 802.16 protocol architecture and WiMAX Market will be discussed. Keywords: WiMAX; IEEE 802.16; Security; Protocol; Market; I. INTRODUCTION WiMAX, meaning Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides wireless transmission of data using a variety of transmission modes, from point-to-multipoint links to portable and fully mobile internet access. The technology provides up to 10 Mbps broadband speed without the need for cables. The technology 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 WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL" [1]. As compared to a wireless technology like Wi-Fi, WiMAX is more immune to interference, allows more efficient use of bandwidth and is intended to allow higher data rates over longer distances. Because it operates on licensed spectrum, in addition to unlicensed frequencies, WiMAX provides a regulated environment and viable economic model for wireless carriers. These benefits, coupled with the technology's global support (e.g., ongoing worldwide deployments, spectrum allocation and standardization), make it the popular choice for quick and cost-effective delivery of super-fast broadband wireless access to underserved areas around the world [2]. WiMAX is cheaper than wired DSL because it does not require placing wires around the area to be covered, which represents an enormous investment for the provider. Not requiring this investment opens the door to many service providers who can start retailing out wireless broadband with low capital, thereby causing prices to drop due to competition . As with any wireless technology, the requirements for WiMAX are basically a transmitter and a receiver. The transmitter is a WiMAX tower, much like a GSM tower. it is the part of the service provider's facilities. One tower, also called a base station, can provide coverage to an area within a radius of around 50 km. On the other side, in order to receive the WiMAX waves, you need a receiver for WiMAX for connecting your computer or device. WiMAX has a range of around 50 km in a circle. Terrain, weather and buildings affect this range and this often results in many people not receiving signals good enough for a proper connection. Orientation is also an issue, and some people have to choose to place their WiMAX modems near windows and turned in certain specific directions for good reception. A WiMAX connection is normally non-line-of-sight, which means that the transmitter and the receiver need not have a clear line between them. But a line-of-sight version exists, where performance and stability is much better, since this does away with problems associated with terrain and buildings [3]. II. WIMAX FUNDAMENTAL ARCHITECTURAL COMPONENTS WiMAX has four fundamental architectural components: Base Station (BS). The BS is the node that logically connects wireless subscriber devices to operator networks. The BS maintains communications with subscriber devices and governs access to the operator networks. A BS consists of the infrastructure elements necessary to enable wireless communications, i.e., antennas, transceivers, and other electromagnetic wave transmitting equipment. BSs are typically fixed nodes, but they may also be used as part of mobile solutions — for example, a BS may be affixed to a vehicle to provide communications for nearby WiMAX devices. A BS also serves as a Master Relay-Base Station in the multi-hop relay topology. Subscriber Station (SS). The SS is a fixed wireless node. An SS typically communicates only with BSs, except for multi- hop relay network operations. SSs are available in both outdoor and indoor models. Mobile Subscriber (MS). Defined in IEEE 802.16e-2005, MSs are wireless nodes that work at vehicular speeds and support enhanced power management modes of operation. MS devices are typically small and self-powered, e.g., laptops, cellular phones, and other portable electronic devices. Relay Station (RS). Defined in IEEE 802.16j-2009, RSs are SSs configured to forward traffic to other RSs, SSs, or MSs in a multi-hop Security Zone [4]. 352 http://sites.google.com/site/ijcsis/ ISSN 1947-5500

a survey on wimax

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