What isautomatic repeat request

Automatic Repeat Request (ARQ), also known as Automatic Repeat Query, is an error control protocol that helps in resending data packets automatically if errors are detected in the transmission.

Error Control Types

The two types of error control are error detection and error correction. Error detection identifies the errors, while error correction fixes them. ARQ’s main function is to provide an acknowledgement to the sender of the successful delivery of data, and if it is not received, the sender retransmits it.

Working of ARQ Protocol

The ARQ protocol involves the sending of a data packet or frame by the sender to the receiver. When the receiver detects erroneous or incorrect data, it sends an acknowledgment signal to the sender asking to resend the data. The sender waits for a predefined period of time, and if within that time, it doesn’t receive the acknowledgment from the receiver, it automatically resends the data packet or frame. If the acknowledgement is still not received, the sender repeats the process of retransmission a predefined number of times until the acknowledgement is received.


ARQ protocol has become an essential component in error control methods used in modern communication systems, especially in cases where data accuracy is critical.


What is the importance of ARQ?

ARQ is an important protocol when it comes to ensuring the accuracy and quality of data in modern communication systems. It prevents the transmission of incorrect or garbled data packets by detecting errors and requesting retransmission until accurate delivery is achieved.

What is the difference between error detection and error correction?

Error detection is the identification of errors that may have occurred during the transmission of data while error correction is the fixing or correction of these errors after detection.

How does the ARQ protocol help to prevent data loss during transmission?

If an acknowledgement signal is not received by the sender within a specific time, it means that either the data packet or frame has been lost or damaged during transmission. The ARQ protocol resends the data packet or frame until the correct transmission is completed.

Final Thoughts

The Automatic Repeat Request protocol is a must-have in modern communication systems. It guarantees the accuracy, completeness, and timeliness of data transfer, making it an invaluable tool in transmitting data accurately.

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