Literature Review Online Billing System

2922 WordsNov 22, 201212 Pages
CDMA BY OKAFOR CHIDUBEM KELVIN 10690152 A SEMINAR REPORT SUBMITTED TO THE DEPARTMENT OF COMPUTER SCIENCE MOSHOOD ABIOLA POLYTECHNIC,ABEOKUTA IN PARTIAL FULFILMENT OF THE AWARD OF NATIONAL DIPLOMA IN COMPUTER SCIENCE NOVEMBER, 2012 CHAPTER 1 1.0 INTRODUCTION Mobile communications are rapidly becoming more and more necessary for everyday activities. With so many more users to accommodate, more efficient use of bandwidth is a priority among cellular phone system operators. Equally important is the security and reliability of these calls. One solution that has been offered is a CODE DIVISION MULTIPLE ACCESS SYSTEM. CDMA is one method for implementing a multiple access communication…show more content…
These systems use digital modulation and processing techniques. TDMA (Time Division Multiple Access), GSM (Global System for Mobile Communication) and (narrowband) CDMA belong to the second generation systems. CDMA was introduced in 1994, by Qualcomm, Inc. Using direct sequence code division multiple access, it claimed to provide 10 times more capacity than analog systems � far more than TDMA or GSM. Today, CDMA is the basis to the third generation market in the United States and other places in the world. 2.2 Background A cellular system is called so because it divides the service area into small transmission areas called cells. Each cell contains a base station (BTS), which consists of a transceiver and a receiver in order to connect to mobile phones in the cell. Each cell is assigned a group of radio channels (frequencies). 3 2.3 The Cellular Challenge The world's first cellular networks were introduced in the early 1980s, using analog radio transmission technologies such as AMPS (Advanced Mobile Phone System). Within a few years, cellular systems began to hit a capacity ceiling as millions of new subscribers signed up for service, demanding more and more airtime. Dropped calls and network busy signals became common in many areas. To accommodate more traffic within a limited amount of radio spectrum, the

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