1 - Introduction

Abstract

This chapter focuses on error-control coding. Errors are classified as one of three types, namely, random errors, burst errors, and byte errors. Random errors occur independently on each symbol. Burst errors occur intensively in a period of data. Byte errors occur in a small block of data. In some cases, mixtures of two of the three types can occur. For each type of error, there exist codes that can effectively detect and/or correct errors of that type. However, a code designed to detect or correct one type of error cannot necessarily be effective for other types. Error-control coding has become an essential part in most of the digital communication and recording systems. As the amount of digital data that must be transmitted or stored reliably increases, error-control coding is becoming more and more important. Because of advances in solid-state electronics technology, codes with large error-correction capability and high efficiency are widely used. In particular, coding systems that employ two codes combined together to obtain better performance, for example, concatenated codes, are often employed.