computer network and communication

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 wireless
transmission, but wireless transmission does not necessarily imply mobile
computing. Fixed wireless applications use satellites, radio systems and lasers to
transmit between permanent objects such as buildings and towers.

2.2 SPECFIACTION, SERVICES AND FREQUENCIES OF MOBILE

COMPUTING

SPECIFICATIONUser Interface

•

S60 5th Edition

Display

•

3.5-inch TFT

•

16 Million Colors

•

mHD 16:9 Widescreen

•

640×360 pixels

Battery

•

Nokia Batter BP-4L

•

1500 mAh

Memory

•

Up to 48GB

•

32GB Internal Memory

•

16GB Micro SD Expansion Slot

Main Camera

•

Carl Zeiss Tessar Lens

•

5MP (2584 x 1938)

•

JPEG/EXIF (16.7 Million / 24-bit color)

•

Video Capture MPEG-4 VGA, 640×480 at 30fps

•

Aperture: F2.8

•

Focal Length: 5.4mm

•

Flash: Dual LED Camera

SERVICES

•

WLAN IEEE 802.11 b/g with UPnP support

•

Micro USB Connector

•

3.5 mm stereo headphone plug

•

TV-Out Support

•

Data transfer via Bluetooth 2.0

•

A-GPS

•

Internet surfing

FREQUENCIES

•

2G Network GSM 850 / 900 / 1800 / 1900

•

3G Network HSDPA 900 / 1900 / 2100

30 INTERNET TECHNOLOGY AND SERVICES

3.1 VoIP

Voice over Internet Protocol(VoIP) is a general term for a family of transmission

technologies for delivery of voice communications over IP (internet protocol)
networks such as the Internet or other packet-switched networks. Other terms
frequently encountered and synonymous with VoIP are IP telephony, Internet
telephony, voice over broadband (VoBB), broadband telephony, and broadband
phone.

Example of VoIP adapter setup

in residential network

3.2 BLOG

A blog is basically a type of
website, like a forum or a social
bookmarking site. As such it is
defined by the technical aspects
and features around it, and not
by the content published inside
it.

secure access to their organization's network. A virtual private networ