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#1 2017-Jul-25 03:32:25

FeilxTang
Member
Registered: 2017-Jul-25
Posts: 2

difference between nomac and dcf

Hi,
I use cellphone to connect to Internet  through AP and use speed test app.I test in case of dcf and nomac.
The result shows that system with nomac is very slow. I don't understand what reason casue it.
Whether nomac can't use for connecting  to Internet?
And I'd like to know what is  nomac's main purpose, and in what situation should we use nomac.

Thank you!

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#2 2017-Jul-25 09:10:46

chunter
Administrator
From: Mango Communications
Registered: 2006-Aug-24
Posts: 1212

Re: difference between nomac and dcf

That behavior is expected. NOMAC gets its name from the fact that it does not implement any kind of Medium Access Control. It's performance should be terrible over the air when sharing the medium with other interferers.

FeilxTang wrote:

And I'd like to know what is  nomac's main purpose, and in what situation should we use nomac.

NOMAC serves three major purposes. First, in controlled experiments where interference can be eliminated (e.g. over a coax cable with sufficient attenuation to not damage the radios), NOMAC can be used to isolate PHY performance from MAC behaviors. We use it to characterize the PHY with things like PER measurements. Second, it's valuable as a way for users to learn the design. Since it doesn't do any Medium Access Control, it's a much simpler design than the DCF. Many users find it easier use NOMAC to learn the basics of transmitting and receiving. Finally, it's intended to be a base of user extensions. The TokenMAC application note uses NOMAC to build a token-passing scheduled MAC.

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