Wireless Access

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Regular Contributor I
Posts: 362
Registered: ‎03-02-2017

Data rate and throughput

Hi there,

 

I have recently read the following:

 

For example, an 802.11g wireless access point has a maximum data rate of 54 Mbps. With one user connected to this access point, chances are the best throughput that could be expected is less than 50 percent of the maximum, or about 20 Mbps. If more users connect
to the same access point, the throughput for each user would be even less, because of the contention between users sharing the same wireless medium.
 
I naturally understand the second part where the more users connected to the network, the lower the throughput. But for the first part (underlined), what is the reason? Is all the throughput lost due to the overhead (management, control frames, etc.)? I knew the overhead reduces throughput, but I thought this doesn't cost up to the 50% of the date rate. Is there any other reason?
 
Regards,
Julián
Guru Elite
Posts: 21,536
Registered: ‎03-29-2007

Re: Data rate and throughput

That is because wireless is half duplex.


Colin Joseph
Aruba Customer Engineering

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Regular Contributor I
Posts: 362
Registered: ‎03-02-2017

Re: Data rate and throughput

Hi Colin,

 

Yes it is, but when it is said that an 802.11g wireless access point has a maximum data rate of 54 Mbps it is already considered that this AP is working in half duplex.

 

Regards,

Julián

Aruba
Posts: 234
Registered: ‎04-27-2009

Re: Data rate and throughput

It's all in the overhead. In my experience we should be able to deliver at least 24Mbps or so of TCP throughput based on the 54Mbps max datarate of an 11a or 11g radio.

This gets progressively more efficient when using 11n or 11ac.

For peak performance with 11ac, we typically expect to see TCP throughput of at least 65% of the max over-the-air datarate.

/Onno
Regular Contributor I
Posts: 362
Registered: ‎03-02-2017

Re: Data rate and throughput

Hi Onno,

 

There are much more overhead than I thought. Many thanks.

 

Regards,

Julián

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