Basics of Wireless Networks

v  SUMARRY

Improved mobile telephone service (IMTS) is the first commercially available radio and telephone system that was put into service in 1946. IMTS was quite unsophisticated, as there were no solid-state electronics available at that time. Although a tall transmitter tower was erected near the center of a metropolitan area, but the number of channel available didn’t come close to satisfying the demand. The solution to this problem was celullar radio. Metropolitan areas were divided into cells of no more than a few  miles in diameter,each cell operating on a set of frequencies (sending and receiving) that differed from the frequencies of the adjacent cells. Two important characteristics of cellular systems contribute to their usefulness, the first is their controlledhandoff, the second is systems were designed to locate particular subscribers by paging them in each of the cells.The initial transmission technology used between the vehicle and the cell site was analog in nature and known as advanced mobile phone system (AMPS): the analog scheme used was called frequency-division multiple access (FDMA). Digital transmission was later developed, resulting in time division multiple Access (TDMA).a few years later, a third group of companies (led by qualcom,inc) developed spread-spectrum technology called code-division access multiple (CDMA). Thus, there are at least four schemes that may be used for communications between a vehicle and the cell site. Communications between the cell site and the switch utilize transmission  media such as microwave, copper pairs,and fiber optics.

v  ABSTRACT

The first commercially available radio and telephone system was the Improved mobile telephone service (IMTS). This system was quite unsophisticated but the number of channels available didn’t come close to satisfying the demand. The solution to this problem was cellular radio. The initial transmission technology used between the vehicle and cell site was analog, known as AMPS (Advanced Mobile Phone System). The analog scheme used called FDMA ( frequency-division multiple access). And digital transmission was later developed was TDMA ( time-division multiple access). This selected known as GSM (Global System for Mobile Communications). Then, the developed spread-spectrum technology called CDMA (code-division multiple access). The developed search was personal communications service (PSC) industry.