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sisting Wi-Fi access points could use the IEEE Std 802.16 solution as a backhaul to deliver signal to the core network. As a last-mile solution, an internet service provider (ISP) could install the IEEE 802.16 technology, instead of cables, DSL, and T1, to deliver services to subscribers. It gives advantages over the traditional wired technology in case that cabling is not feasible or too expensive, for example, implementing in rural areas or developing countries where lack wired network infrastructures[12].

Two usage models of the IEEE Std 802.16. The IEEE Std 802.16 base station provides wireless access services to fixed and portable subscribers. The fixed subscribers could be residential subscribers or businesses in buildings. For residential subscribers, the standard provides broadband wireless access as a last-mile solution, in place of using cable modem. The IEEE 802.16 technology can be a substitute to DSL or leased line services for small and medium size businesses, as well as a substitute to T1/E1 level services for enterprises. Users in the buildings can join to the network via Ethernet/IEEE 802.3 or WLAN/IEEE 802.11 standards. For mobile users, the IEEE Std 802.16e which is an amendment to IEEE Std 802.16-2004 adds the capability to provide services. The users can directly attach to the network using devices, such as personal digital assistants (PDAs), smart phones, and mobile laptops.

2.5 OVERVIEW of WiMAX
The IEEE 802.16 standard is commercially known as WiMAX, which is an acronym for Worldwide Interoperability for Microwave Access. WiMAX is a wireless metropolitan-area network technology that provides interoperable broadband wireless connectivity to fixed, portable and nomadic users. It covers up to 50- kilometers of service area, permit users to obtain broadband connectivity with no 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[2].

WiMAX covers a broad spectrum of bandwidth from a few hundred megahertz to tens of GHz. This encompasses far more spectrum than any earlier standard. WiMAX is intended to become a 'Next Big Thing' analogous to the impact of the Internet because WiMAX is built on open standards and is extensively accepted by regulatory agencies and standards groups around the globe. This universal level of approval means that products can be prepared that will work wherever comparable service is provided.

It has been developing by the WiMAX Forum working groups. The WiMAX Forum established in June 2001 and is a nonprofit organization. The intend of the organization, similar to Wi-Fi Alliance, is to make sure the compatibility and interoperability of products conforming to the IEEE Std 802.16 and European Telecommunications Standards Institute (ETSI) HiperMAN standards. WiMAX plays a role as a complement of the IEEE Std 802.16. The IEEE 802.16 working group defines the standard for working, whereas the WiMAX Forum coordinates companies to make sure that equipment from each company can well operate with one another.

The WiMAX Forum creates system profiles and defines test suite for conformance and interoperability. “WiMAX Forum CERTIFIEDa„￠” text and logo will be used by the equipment that passes the test and will be certified. The trademarks are shown in Figur本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。