RTS/CTS (request to send / clear to send) is the optional mechanism used by the 802.11 wireless networking protocol to reduce frame collisions introduced by the hidden node problem. Originally the protocol fixed the exposed node problem as well, but modern RTS/CTS includes ACKs and does not solve the exposed node problem.
The RTS, CTS and ACK frame headers all contain a frame control field (two bytes of metadata flags), duration field, a field for the receiver MAC address, and a frame check sequence. Additionally, an RTS frame contains the transmitter's MAC address.
This protocol was designed under the assumption that all nodes have the same transmission ranges, and does not solve the hidden terminal problem. The RTS/CTS frames can cause a new problem called the exposed terminal problem in which a wireless node that is nearby, but is associated with another access point, overhears the exchange and then is signaled to back off and cease transmitting for the time specified in the RTS.
The RTS/CTS packet size threshold is 0–2347 octets. Typically, sending RTS/CTS frames does not occur unless the packet size exceeds this threshold. If the packet size that the node wants to transmit is larger than the threshold, the RTS/CTS handshake gets triggered. Otherwise, the data frame gets sent immediately.
IEEE 802.11 RTS/CTS mechanism could help solve[according to whom?] exposed node problem as well, only if the nodes are synchronized and packet sizes and data rates are the same for both the transmitting nodes. When a node hears an RTS from a neighboring node, but not the corresponding CTS, that node can deduce that it is an exposed node and is permitted to transmit to other neighboring nodes.[1] If the nodes are not synchronized (or if the packet sizes are different or the data rates are different) the problem may occur that the exposed node will not hear the CTS or the ACK during the transmission of data of its neighbor.
^Bharghavan; et al. (1994-10-01). "MACAW: A Media Access Protocol for Wireless LAN's". ACM SIGCOMM Computer Communication Review. In the Proc. ACM SIGCOMM Conference (SIGCOMM '94), August 1994, pages 212-225. 24 (4): 212–225. doi:10.1145/190809.190334. S2CID 243278854. Retrieved 2017-03-10.
External linksedit
"A New Channel Access Method for Packet Radio" 2011-07-20 at the Wayback Machine
ieee, this, article, multiple, issues, please, help, improve, discuss, these, issues, talk, page, learn, when, remove, these, template, messages, this, article, require, cleanup, meet, wikipedia, quality, standards, specific, problem, copyedit, looks, like, co. This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages This article may require cleanup to meet Wikipedia s quality standards The specific problem is copyedit looks like copy paste with line wrap 1 may be ref to EXT 1 Please help improve this article if you can April 2013 Learn how and when to remove this message This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations April 2013 Learn how and when to remove this message This article needs additional citations for verification Please help improve this article by adding citations to reliable sources in this article Unsourced material may be challenged and removed Find sources IEEE 802 11 RTS CTS news newspapers books scholar JSTOR May 2010 Learn how and when to remove this message Learn how and when to remove this message RTS CTS request to send clear to send is the optional mechanism used by the 802 11 wireless networking protocol to reduce frame collisions introduced by the hidden node problem Originally the protocol fixed the exposed node problem as well but modern RTS CTS includes ACKs and does not solve the exposed node problem Contents 1 Frame format 2 See also 3 References 4 External linksFrame format editThe RTS CTS and ACK frame headers all contain a frame control field two bytes of metadata flags duration field a field for the receiver MAC address and a frame check sequence Additionally an RTS frame contains the transmitter s MAC address This protocol was designed under the assumption that all nodes have the same transmission ranges and does not solve the hidden terminal problem The RTS CTS frames can cause a new problem called the exposed terminal problem in which a wireless node that is nearby but is associated with another access point overhears the exchange and then is signaled to back off and cease transmitting for the time specified in the RTS RTS CTS is an additional method to implement virtual carrier sensing in carrier sense multiple access with collision avoidance CSMA CA By default 802 11 relies on physical carrier sensing only which is known to suffer from the hidden node problem The RTS CTS packet size threshold is 0 2347 octets Typically sending RTS CTS frames does not occur unless the packet size exceeds this threshold If the packet size that the node wants to transmit is larger than the threshold the RTS CTS handshake gets triggered Otherwise the data frame gets sent immediately IEEE 802 11 RTS CTS mechanism could help solve according to whom exposed node problem as well only if the nodes are synchronized and packet sizes and data rates are the same for both the transmitting nodes When a node hears an RTS from a neighboring node but not the corresponding CTS that node can deduce that it is an exposed node and is permitted to transmit to other neighboring nodes 1 If the nodes are not synchronized or if the packet sizes are different or the data rates are different the problem may occur that the exposed node will not hear the CTS or the ACK during the transmission of data of its neighbor See also editRS 232 RTS CTS RS 232 RTS CTS flow control Multiple Access with Collision Avoidance for WirelessReferences edit Bharghavan et al 1994 10 01 MACAW A Media Access Protocol for Wireless LAN s ACM SIGCOMM Computer Communication Review In the Proc ACM SIGCOMM Conference SIGCOMM 94 August 1994 pages 212 225 24 4 212 225 doi 10 1145 190809 190334 S2CID 243278854 Retrieved 2017 03 10 External links edit A New Channel Access Method for Packet Radio Archived 2011 07 20 at the Wayback Machine IEEE 802 11 frame format at the Wayback Machine archived January 10 2020 Retrieved from https en wikipedia org w index php title IEEE 802 11 RTS CTS amp oldid 1174942018, wikipedia, wiki, book, books, library,
