Communications Blockset

Cyclic Redundancy Check Coding

Cyclic redundancy check (CRC) coding is an error-control coding technique for detecting errors that occur when a message is transmitted. Unlike block or convolutional codes, CRC codes do not have a built-in error correction capability. Instead, when an error is detected in a received message word, the receiver requests the sender to retransmit the message word.

In CRC coding, the transmitter applies a rule to each message word to create extra bits, called the checksum, or syndrome, and then appends the checksum to the message word. After receiving a transmitted word, the receiver removes the appended checksum, applies the same rule to the truncated word, and compares the resulting checksum with the received checksum. If the two checksums differ, an error has occurred, and the transmitter must resend the message word.

Selected Bibliography for Convolutional Coding

Organization of this Section