“WiMAX”: Promising Wireless Technology
Amir H. Dehghan
Department of Computer Sc. University of Pune
Maharashtrat, Pune. India
ABSTRACT– 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 without 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.
Keywords: WiMax, QoS, DSL, OFDM, OFDMA, MAN, LOS, NLOS, CDMA
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.
II.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.
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