4 – Error detection

Publisher Summary This chapter presents the basic concepts of error detection in data communication systems. Errors in data communications occur when the value of a bit is altered from 1 to 0 or vice versa. Errors are produced by static events, such as thermal noise and transient events. There are two approaches for dealing with errors in a message: —feedback error control and forward error correction. The feedback error control is where the receiver is able to detect the presence of errors in the message sent by the transmitter. The detected error cannot be corrected, but its presence is indicated. Forward error correction is where the receiver can not only detect the presence of error in a message, but also reconstruct the message into what it believes to be the correct form. It may be used where there are long delays in requesting retransmission of messages or where the originating transmitter has difficulty in retransmitting the message when the receiver discovers an error. This chapter discusses how errors are produced as well as the types of error detection, control, and correction available. It also explains the factors affecting the propagation of signals. Methods of feedback error control as well as forward error correction are also elaborated in the chapter.