Talk:Carrier sense multiple access

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[edit] Restructuring of CMSA, CMSA/CD, CMSA/CA Pages (1 Nov 2003)

There was already a minimal CSMA article in place. Since CSMA/CD and CSMA/CA are both variants of CSMA, I moved detailed discussion of the fundamental algorithm into the CSMA article, and restructured CSMA/CD to describe the value it adds to CSMA. I plan to do the same for CSMA/CA. I also added a ghost link in the CSMA article for MAC.

[edit] Need to add: Deterministic CSMA/CA

I know there exists another type of CSMA/CA that is entirely deterministic, ie that cannot lead to collision even if both ends speak at exactly the same time. It is used in some field networks, I cant remember which ones. I dont know enough of it, nor am i able to cite sources, so I describe it here hoping somebody will modify the article for me. thanks in advance to the one who will.

The principle is roughly: anybody wanting to speak first broadcasts its own address with '0' bits being recessive (much like tri-stated bits) on the medium; and re-reads its own address. If it reads something else than its address, it immediately stops and retries after the end of packet. This means the equipment with "11111.." address is able to speak whenever it wants to, and others follow, the highest address having the highest priority.

- Ppchailley 16:59, 4 July 2006 (UTC)

In fact it does exist and is only one form of CSMA/BA. There is a paragraph about it right now. It may still need an example, though... 84.101.111.34 08:10, 5 July 2006 (UTC)

The sentence "all of the nodes on the bus are assigned an identification number or priority code." isn't completely correct
in the context of CAN which is given as example for CSMA/BA. CAN doesn't assign identification numbers to nodes, but to
message types. Therefor you can't prioritize an particular node but particular messages which could be send by any node.
On the other some vendors use parts of the message ids as address informations. Unsignedvoid (talk) 08:00, 17 April 2008 (UTC)

Please check that you haven't got collision avoidance and collision detection mixed up. Some companies are definitely using "collision avoidance" to describe the random wait variants, which is logical - it doesn't detect a collision, it just avoids one being set up. So collision detection goes for the previous variant. —Preceding unsigned comment added by Neve Dan (talk • contribs) 18:30, 17 January 2008 (UTC)

Ppchailley and "84.101.111.34" are correct -- he's describing the system used by Controller Area Network (and well described in that article). In that system, two simultaneous transmitters never garble a packet -- all receivers will hear a valid packet from either one or the other transmitter. --68.0.124.33 (talk) 05:08, 5 April 2008 (UTC)

[edit] CSMA/CA

the part of CSMA/CA is realy bad explained, I needed to reread it in german wiki for understanding Antrophos (talk) 17:47, 5 March 2008 (UTC)

I added a few sentences. Does it make better sense now? --68.0.124.33 (talk) 05:08, 5 April 2008 (UTC)

[edit] CSMA/CD

--BelieveAndy (talk) 13:47, 4 April 2008 (UTC) Write soon.

[edit] CSMA/NDA

The "on-board diagnostics" article mentions something called 'Carrier Sense Multiple Access with Non-Destructive Arbitration' (CSMA/NDA).

At first I thought it was talking about Controller Area Network. However, the article claims that CSMA/NDA was used on a "PWM" system long before CANbus.

If someone could find some reference to this "PWM" protocol (and no, the pulse-width modulation says nothing about automobile electronics protocols), that would be great. "CSMA/NDA" -- is it, or is it not, yet another synonym for CSMA/BA ? --68.0.124.33 (talk) 05:08, 5 April 2008 (UTC)

[edit] Does Bluetooth (802.15.1) really use CSMA-CA?

In "Protocols Using CSMA" it is stated that all 802.15 standards use the CSMA, but as far as I remember Bluetooth uses an master controlled channel access without CSMA. —Preceding unsigned comment added by 145.253.172.3 145.253.172.3 (talk) 07:34, 17 April 2008 (UTC)

[edit] expansion

Need to add p persistent, non persistent and 1 persistent CSMA info. --Sylvestersteele (talk) 10:38, 11 May 2008 (UTC)