Distributed coordination function: Difference between revisions

Revision as of 01:32, 13 July 2023

Revision as of 09:14, 15 February 2024

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<math>\mathrm{Backoff Time} = \mathrm{random}() \times \mathrm{aSlotTime}</math><ref>{{Cite web|title=IEEE 802.11-2016 - IEEE Standard for Information technology--Telecommunications and information exchange between systems Local and metropolitan area networks--Specific requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications|url=https://standards.ieee.org/standard/802_11-2016.html|access-date=2021-05-27|website=standards.ieee.org}}</ref>

A few features about DCF:

DCF also has an optional virtual carrier sense mechanism that exchanges short Request-to-send (RTS) and Clear-to-send (CTS) frames between source and destination stations during the intervals between the data frame transmissions.

DCF also* has an optional virtual carrier sense mechanism that exchanges short [[RTS/CTS|Request-to-send (RTS)]] and [[RTS/CTS|Clear-to-send (CTS)]] frames between source and destination stations during the intervals between the data frame transmissions.;

DCF* includes a positive acknowledge scheme, which means that if a frame is successfully received by the destination it is addressed to, the destination needs to send an ACK frame to notify the source of the successful reception.;

DCF* it does not solve the [[Hidden node problem|hidden node]] and/or exposed terminal problem completely, it only alleviates the problem through the use of RTS and CTS, and recommends the use of a larger carrier sensing range.;

DCF* it is defined in the IEEE 802.11 standard and is the de facto default setting for Wi-Fi hardware.

DCF is defined in the IEEE 802.11 standard and is the de facto default setting for Wi-Fi hardware.

802.11 DCF consumes a significant amount of airtime, 802.11 control messages usually convey very little information. For example, an ACK message can take up to 60 μs to transmit completely, which includes an amount of airtime sufficient to transmit 3240 bits at 54 Mbit/s, during which it conveys a single bit of relevant information.