Talk:Carrier-sense multiple access with collision avoidance: Difference between revisions
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I would remove the performance section altogether. DSSS and FHSS are phy layer techniques and they are somewhat orthogonal to the layer-2 protocol. In fact, new devices use ofdm or mimo-ofdm at the phy layer. The widely cited paper of Bianchi in jsac 2000 offers a performance analysis of dcf, which is a particular implementation of csma/ca. [[User:Jbarcelo|Jbarcelo]] ([[User talk:Jbarcelo|talk]]) 10:42, 31 October 2010 (UTC)
== Optional RTS/CTS - Concept vs. standard confusion! ==
I believe that sometimes CSMA/CA refers to the concept itself (adding RTS/CTS to CSMA) and sometimes it refers specifically to the CSMA/CA defined in the 802.11 family (not sure when or in which ammendment). However the RTS/CTS part is optional in the 802.11 standard. I am not sure if it means that the manufacturer does not even need to implement it (don't think so) or if it only means that you can disable it in the settings for your 802.11 networking card or AP? So when people read that CA is optional in CSMA/CA, it refers to the choice by IEEE to make the implementation of RTS/CTS optional.
As always Tanenbaum has an explanation that makes sense. From 'Computer Networks', 5th edition, section 4.4, pg. 324.
<blockquote>
''However, while RTS/CTS sounds good in theory, it is one of those designs that has proved to be of little value in practice. Several reasons why it is seldom used are known. It does not help for short frames (which are sennt in place of the RTS) or for the AP (which everyone can hear, by definition). For other situations, it only slows down operation. RTS/CTS in 802.11 is a little different than in the MACA protocol we saw in Sec 4.2 because everyone hearing the RTS or CTS remains quiet for the duration to allow the ACK to get through without collision. Because of this, it does not help with exposed terminals as MACA did, only with hidden terminals. Most often athere are few hidden terminals, and CSMA/CA already helps them by slowing down stations that transmit unseccessfully, whatever the cause, to make it more likely that transmission will succeed''
</blockquote>
However if talking about the ''concept'' of CSMA with CA, of course CA an inherent defining feature.
[[Special:Contributions/85.97.254.28|85.97.254.28]] ([[User talk:85.97.254.28|talk]]) 20:07, 11 May 2012 (UTC)
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