12-11-2009, 11:53 AM
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ABSTRACT
Fourth generation wireless system is a packet switched wireless system with wide area coverage and high throughput. It is designed to be cost effective and to provide high spectral efficiency . The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB),and Millimeter wireless. Data rate of 20mbps is employed. Mobile speed will be up to 200km/hr.The high performance is achieved by the use of long term channel prediction, in both time and frequency, scheduling among users and smart antennas combined with adaptive modulation and power control. Frequency band is 2-8 GHz. it gives the ability for world wide roaming to access cell anywhere.
1. INTRODUCTION
Wireless mobile-communications systems are uniquely identified by "generation" designations. Introduced in the early 1980s, first-generation (1G) systems were marked by analog-frequency modulation and used primarily for voice communications. Second - generation (2G) wireless-communications systems, which made their appearance in the late 1980s, were also used mainly for voice transmission and reception The wireless system in widespread use today goes by the name of 2.5Gâ€an "in-between" service that serves as a stepping stone to 3G. Whereby 2G communications is generally associated with Global System for Mobile (GSM) service, 2.5G is usually identified as being "fueled" by General Packet Radio Services (GPRS) along with GSM.
In 3G systems, making their appearance in late 2002 and in 2003, are designed for voice and paging services, as well as interactive-media use such as teleconferencing, Internet access, and other services. The problem with 3G wireless systems is bandwidthâ€these systems provide only WAN coverage ranging from 144 kbps (for vehicle mobility applications) to 2 Mbps (for indoor static applications). Segue to 4G, the "next dimension" of wireless communication. The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB), and Millimeter wireless and smart antenna. Data rate of 20mbps is employed. Mobile speed will be up
to 200km/hr.Frequency band is 2-8 GHz. it gives the ability for world wide roaming to access cell anywhere.
