CHAPTER ONE
GENERAL INTRODUCTION
1.1.0 INTRODUCTION
In recent times, there has been a great need driven towards the maximizing of data transfer between communication terminals thereby
making efficient use of network bandwidth and disk space. Compression is the process used to reduce the physical size of a block of
information. Data encoding is the term used to refer to algorithms that perform compression. Data compression is a type of data
encoding. Doyle and Carlson (2000) write that data compression “has one of the most simple and elegant design theories in all
engineering”. A simple characterization of data is that it involves transforming a string of characters in some representation (such as ASCII)
into a new string (0f bits for example) which contains the same information, but whose length is as small as possible. Data compression
squeezes data so it requires less disk space storage, less bandwidth on a data transmission channel. Communication equipment’s like
modems, bridges and routers use compression scheme to improve throughput over standard leased lines or phone lines.
File compression can be employed at various levels; a user can choose to compress individual files, a whole folder or the whole of a
drive. Most compression schemes take advantage of the fact that data contains a lot of repetitions. For example, alphanumeric characters
are normally represented by a 7-bit ASCII code but a compression scheme can use a 3-bit code to represent its most common letters.
Compressed files are called archives. Archives can contain more than one file. Archive files are manipulated with utilities such as WinZip or
IZArc.
1.2.0 PROBLEM DEFINITION
Many sources of information contain redundant data or data that adds little to the stored information. This results in tremendous
amount of data being transferred between client and server application. Many times lots and lots of information is to be transferred over a
communication channel; this information if not compressed requires a lot of disk space for storage. Similarly, it is important to note that large bits of information require large bandwidth over a transmission channel. This bandwidth is measured in bits/seconds which makes it costly. A large chunk of information require more transmission time than less information. All these factors are the problems that gave
rise to the need for compression.
1.3.0 OBJECTIVE OF THE STUDY
There are many reasons for data compressions; the main aim of data compression is to reduce redundancy by reducing storage
requirements. When the amount of data to be transmitted is reduced, the eect is that of increased storage capacity of the
communication channel. Similarly, compressing a file to half its original size is equivalent to doubling the capacity of the storage medium.
It may then become flexible to store the data at a higher rate thus faster level of storage hierarchy and reduce the load on the
input/output channels of the computer system.
One objective of this project is to achieve a faster file transfer as well as make use of less bandwidth on a data. For data
communication, the transfer of compressed data over medium results in the increase in the rate of information transfer. This is another
aim of file compression.