computer networks and Communications

10 INTRODUCTION
The purpose of a computer communications network is to allow moving information from one point to another inside the network. The information could be stored on a device, such as a personal computer in the network, it could be generated live outside the network, such as speech, or could be generated by a process on another piece of information, such as automatic sales transactions at the end of a business day. The device does not necessarily have to be a computer; it could be a hard disk, a camera or even a printer on the network. Due to a large variety of information to be moved, and due to the fact that each type of information has its own conditions for intelligibility, the computer network has evolved into a highly complex system. Specialized knowledge from many areas of science and engineering goes into the design of networks. It is practically impossible for a single area of science or engineering to be entirely responsible for the design of all the components. Therefore, a study of computer networks branches into many
areas as we go up from fundamentals to the advanced levels.
20 MOBILE COMPUTING
2.1 DEFINITION
Using a computing device while in transit. Mobile computing implies wirelesstransmission, but wireless transmission does not necessarily imply mobilecomputing. Fixed wireless applications use satellites, radio systems and lasers totransmit between permanent objects such as buildings and towers.