4G Wireless Systems
4G Wireless Systems or Fourth generation wireless system is a packet switched wireless network with broad 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. The data rate 20 Mbps is employed. Mobile speed will be up to 200 km/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. The frequency band is 2-8 GHz. It gives the ability for massive world roaming to access cell anywhere.
Wireless cellular communications structures exist uniquely diagnosed by using “technology designations. Introduced in early 1980, first generation (1G) networks marked by using analogue frequency modulation and used commonly for voice communications. Second generation (2G) wireless communications systems, which made their appearance inside the overdue Eighties, had been extensively utilised 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 associated with Global System for Mobile (GSM) service, 2.5G usually identified as being “fueled ” by General Packet Radio Services (GPRS) along with GSM. In 3G systems, making their appearance in late 2002 and 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 to 2 Mbps. Segue to 4G, the “next dimension ” of wireless communication. 4g wireless uses Orthogonal Frequency Division Multiplexing, Ultra Wide Radio Band and Millimeter wireless and smart antenna. The data rate of 20 Mbps is employed. Mobile speed will be up to 200 km/hr.The frequency band is 2 ]8 GHz. It gives the ability for vast world roaming to access cell anywhere.
Features of 4G Wireless Systems:
- Support for interactive multimedia, voice, streaming video, Internet, and other broadband services
- IP based mobile system
- high capacity, High speed, and low cost per bit
- Global access, service portability, and scalable mobile services
- A variety of Quality of Service and Seamless switching 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 severe problem)
- Better spectral efficiency
- A seamless network of multiple protocols and air interfaces
- An infrastructure to handle pre-existing 3G systems along with other wireless technologies, some of which are currently under development.