Automatic Repeat Request

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automatic repeat request

[¦ȯd·ə¦mad·ik ri′pēt ri‚kwest]
(computer science)
A request from a receiving device to retransmit the most recent block of data. Abbreviated ARQ.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Automatic Repeat Request

(ARQ) A modem error control protocol in which the receiver asks the transmitter to resend corrupted data.
This article is provided by FOLDOC - Free Online Dictionary of Computing (


(Automatic Repeat reQuest) A set of protocols for handling communications errors in which the receiving station requests retransmission if an error occurs. The ARQ is a layer 2 data link protocol (see OSI model).

Stop-and-Wait ARQ
The sender waits for an acknowledgment (ACK) before sending the next frame. If the sender does not receive an ACK within a certain amount of time, or if it receives a not-acknowledged (NAK) message, the frame is retransmitted.

Go-Back-N ARQ
Multiple frames are sent, and the sender waits for all frames to be acknowledged. If there is a NAK for any frame, or if there is no ACK for all the frames, the entire set is retransmitted.

Selective Repeat ARQ
Similar to Go-Back-N ARQ, except that only the frame that did not receive a NAK is retransmitted.
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References in periodicals archive ?
patent for its award-winning DOZER[TM] ARQ (Automatic Repeat reQuest) technology, which guarantees error-free real-time UDP video transmission over congested IP networks, including the Internet, and over long distances.
For reliable video quality over the public internet and across long distances, the iCandy encoder and decoder are equipped with DVEO's patented DOZER[TM] ARQ (Automatic Repeat Request) technology for UDP packet recovery for IP transmission.

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