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Introduction
WiMAX (World Interoperability for Microwave Access), based on IEEE802.16 standard is a broadband wireless technology that enjoys widespread support from both the computer and telecom industries worldwide, making this technology particularly costeffective. It is engineered to deliver significant business benefits to operators and users in diverse environments (enterprise, consumer, emerging, public service), geographies and demographies (urban, suburban, rural), both over the short and long terms. This paper attempts to present the key technical features and applications of WiMAX, and illustrate them by providing examples of usage scenarios in which WiMAX would be the preferred solution.
There are two main applications of WiMAX today: fixed WiMAX applications And mobile applications. Fixed applications are point to multipoint enabling broadband access to homes and businesses. Mobile applications offer full mobility of cellular networks at true broadband speed.There are many usage scenarios that can be addressed , however, the limited length of this paper means that we cannot address all of them. For this reason, the paper is primarily focused on fixed and portable usage; however, some examples of mobility usage have also been included.
WiMAX technology makes the following possible:
• Make portable internet a reality by extending public WLAN hotspots to metropolitan area coverage for mobile data-centric service delivery
• Connect enterprises and residentialv users in urban and suburban environment where access to copper plant/wire network is difficult.
• Bridge the digital divide by delivering broadband in low density areas.
WiMAX Technology
The WiMAX standard has been developed with many objectives in mind. These are summarized below:
High Security
•Flexible Architecture: WiMAX supports several system architectures, including Point-to-Point, Point-to-Multipoint, and ubiquitous coverage. The WiMAX MAC (Media Access Control) supports Point-to-Multipoint and ubiquitous service by scheduling a time slot for each Subscriber Station (SS). If there is only one SS in the network, the WiMAX Base Station (BS) will communicate with the SS on a Point-to-Point basis. A BS in a Point-to-Point configuration may use a narrower beam antenna to cover longer distances.
•High Security: WiMAX supports AES (Advanced Encryption Standard) and 3DES (Triple DES, where DES is the Data Encryption Standard). By encrypting the links between the BS and the SS, WiMAX provides subscribers with privacy (against eavesdropping) and security across the broadband wireless interface. Security also provides operators with strong protection against theft of service. WiMAX also has built-in VLAN support, which provides protection for data that is being transmitted by different users on the same BS.
AX Service Types
•Quick Deployment: Compared with the deployment of wired solutions, WiMAX requires little or no external plant construction. For example, excavation to support the trenching of cables is not required. Operators that have obtained licenses to use one of the licensed bands, or that plan to use one of the unlicensed bands, do not need to submit further applications to the Government. Once the antenna and equipment are installed and powered, WiMAX is ready for service. In most cases, deployment of WiMAX can be completed in a matter of hours, compared with months for other solutions.
•Multi-Level Service: The manner in which QoS is delivered is generally based on the Service Level Agreement (SLA) between the service provider and the end-user. Further, one service provider can offer different SLAs to different subscribers, or even to different users on the same SS.
•Interoperability: WiMAX is based on international, vendor-neutral standards, which make it easier for end-users to transport and use their SS at different locations, or with different service providers. Interoperability protects the early investment of an operator since it can select equipment from different equipment vendors, and it will continue to drive the costs of equipment down as a result of mass adoption.
•Portability: As with current cellular systems, once the WiMAX SS is powered up, it identifies itself, determines the characteristics of the page link with the BS, as long as the SS is registered in the system database, and then negotiates its transmission characteristics accordingly.
•Mobility: The IEEE 802.16e amendment has added key features in support of mobility. Improvements have been made to the OFDM and OFDMA physical layers to support devices and services in a mobile environment. These improvements, which include Scaleable OFDMA, MIMO, and support for idle/sleep mode and hand-off, will allow full mobility at speeds up to 160 km/hr. The WiMAX Forum-supported standard has inherited OFDM’s superior NLOS (Non-Line Of Sight) performance and multipath-resistant operation, making it highly suitable for the mobile environment.
•Cost-effective: WiMAX is based on an open, international standard. Mass adoption of the standard, and the use of low-cost, mass-produced chipsets, will drive costs down dramatically, and the resultant competitive pricing will provide considerable cost savings for service providers and end-users.
•Wider Coverage: WiMAX dynamically supports multiple modulation levels, including BPSK, QPSK, 16-QAM, and 64-QAM. When equipped with a high-power amplifier and operating with a low-level modulation (BPSK or QPSK, for example), WiMAX systems are able to cover a large geographic area when the path between the BS and the SS is unobstructed.
•Non-Line-of-Sight Operation: NLOS usually refers to a radio path with its first Fresnel zone completely blocked. WiMAX is based on OFDM technology, which has the inherent capability of handling NLOS environments. This capability helps WiMAX products deliver broad bandwidth in a NLOS environment, which other wireless product cannot do.
