INTRODUCTION4G Wireless Systems or 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 worldwide roaming to access cell anywhere. 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 2.5G-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 bandwidth-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 worldwide roaming to access cell anywhere.Advantages of 4G Wireless Systems: * Support for interactive multimedia, voice, streaming video, Internet, and other broadband services * IP based mobile system * High speed, high capacity, and low cost per bit * Global access, service portability, and scalable mobile services * Seamless switching, and a variety of Quality of Service driven services * Better scheduling and call admission control techniques * Ad hoc and multi hop networks (the strict delay requirements of voice make multi hop network service a difficult problem) * Better spectral efficiency * Seamless network of multiple protocols and air interfaces * An infrastructure to handle preexisting 3G systems along with other wireless technologies, some of which are currently under development.4G technologies are significant because users joining the network add mobile routers to the network infrastructure. Because users carry much of the network with them, network capacity and coverage is dynamically shifted to accommodate changing user patterns. As people congregate and create pockets of high demand, they also create additional routes for each other, thus enabling additional access to network capacity. Users will automatically hop away from congested routes to less congested routes. This permits the network to dynamically and automatically self-balance capacity, and increase network utilization. What may not be obvious is that when user devices act as routers, these devices are actually part of the network infrastructure. So instead of carriers subsidizing the cost of user devices (e.g., handsets, PDAs, of laptop computers), consumers actually subsidize and help deploy the network for the carrier. With a cellular infrastructure, users contribute nothing to the network. They are just consumers competing for resources. But in wireless ad hoc peer-to-peer networks, users cooperate - rather than compete - for network resources. Thus, as the service gains popularity and the number of users increases, service likewise improves for all users. And there is also the 80/20 rules. With traditional wireless networks, about 80% of the cost is for site acquisition and installation, and just 20% is for the technology. Rising land and labor costs means installation costs tend to rise over time, subjecting the service providers 7 business models to some challenging issues in the out years. With wireless peer-to-peer networking, however, about 80% of the cost is the technology and only 20% is the installation. Because technology costs tend to decline over time, a current viable business model should only become more profitable over time. The devices will get cheaper, and service providers will reach economies of scale sooner because they will be able to pass on the infrastructure savings to consumers, which will further increase the rate of penetration | | | | |