World Library  
Flag as Inappropriate
Email this Article

Automatic repeat-request

Article Id: WHEBN0022263725
Reproduction Date:

Title: Automatic repeat-request  
Author: World Heritage Encyclopedia
Language: English
Subject: OSI model, Secure Communications Interoperability Protocol, HomePlug, Selective Repeat ARQ, Hybrid automatic repeat request, Packet loss concealment, Link Access Procedure for Modems, E-UTRA, AN/PRC-150
Publisher: World Heritage Encyclopedia

Automatic repeat-request

Automatic Repeat reQuest (ARQ), also known as Automatic Repeat Query, is an error-control method for data transmission that uses acknowledgements (messages sent by the receiver indicating that it has correctly received a data frame or packet) and timeouts (specified periods of time allowed to elapse before an acknowledgment is to be received) to achieve reliable data transmission over an unreliable service. If the sender does not receive an acknowledgment before the timeout, it usually re-transmits the frame/packet until the sender receives an acknowledgment or exceeds a predefined number of re-transmissions.

The types of ARQ protocols include

All three protocols usually use some form of sliding window protocol to tell the transmitter to determine which (if any) packets need to be retransmitted.

These protocols reside in the Data Link or Transport Layers of the OSI model.

A number of patents exist for the use of ARQ in live video contribution environments. In these high throughput environments negative acknowledgements are used to drive down overheads.


The Transmission Control Protocol uses a variant of Go-Back-N ARQ to ensure reliable transmission of data over the Internet Protocol, which does not provide guaranteed delivery of packets; with Selective Acknowledgement (SACK), it uses Selective Repeat ARQ.

The ITU-T standard, which provides a way to create a high-speed (up to 1 Gbit/s) local area network using existing residential wiring (power lines, telephone lines, and coaxial cables), uses Selective Repeat ARQ to ensure reliable transmission over noisy media.

See also


  • Peterson and Davie, Computer Networks: A Systems Approach, Third Edition, 2003
  • RFC 3366 - Advice to link designers on link Automatic Repeat reQuest (ARQ)
  • Negative acknowledgement ARQ for live video
  • ┬áThis article incorporates┬áMIL-STD-188).
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.