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mattix mattix
 

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M$1.00  Funded By Mahalo ? |  March 28, 2009 11:45 PM

How do you calculate net bit rate for 802.11 wireless (a,b,g, and n).

Need help answering the following question:

Calculate the data rates of the different modes based on the information: Modulation, Frequency band and channel allocation, spread spectrum.

Basically I need to show how to prove that the net bit rate for 802.11g is 54Mbps for example.

Thanks in advance.
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xds xds
 
 March 29, 2009 01:56 AM
That entirely depends on a whole host of variables, one being what platform you are using, another being how fast your ISP is.

But in general you can't just calculate your answer if you are a end user.

But I will try and give you my best answer.
Theoretically under optimal circumstances you can use iperf to calculate your final figures.
But again this will all come down to unforeseen variables such as network speed, network congestion and so on and so forth.

If you could give me some more details about what it is you need this for I might be able to help you further.

Kind Regards,
XDS

PS: Here is a link where you can get some more information on frequency modulation .

http://en.wikipedia.org/wiki/IEEE_802.11g-2003

GOOD LUCK!
Source(s):
My Brain.

Asker's Rating:
• Not exactly what I was looking for, but still good information.


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mattix mattix
 
March 29, 2009 02:18 AM
Hi xds,

What I need to know is the calculation to determine theoretical net bit rate.
So not what you would experience as client, but what the maximum number of bits per second each mode can support.

Example:

I know 802.11g supports 54Mbps as its net bit rate and 802.11n supports 600Mbps as its net bit rate.

What I need to know is the method in which these net bit rates are found(a formula, or some proof to demonstrate how the net bit rate is obtained).

maybe in the form of:
net bit rate= X+Y*Z =600Mbps

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mattix mattix
 
March 29, 2009 02:21 AM
http://en.wikipedia.org/wiki/Net_bitrate#Physical_layer_net_bit_rate
This page provides the definition of the net bitrate but does not explain how to calculate this value.

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xds xds
 
March 29, 2009 02:41 AM
The thing is mattix 802.11 uses different rates depending on signal strength.

So this "calculatory" formula would be extremely difficult to produce.

Because of different changing environment conditions.

Can you give me a general type of environment .

Or in other words what is your "static" environment for the calculation ?

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xds xds
 
March 29, 2009 02:46 AM
Also, please bear in mind a few things 802.11 uses different rates depending on signal strength, it also switches back and forth between 802.11b and 802.11g depending on your environment.

I would also need to know what both the client and the host are using to communicate. (Or it would help atleast)

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xds xds
 
March 29, 2009 02:50 AM
Also a couple final important things (and sorry for so many multiple comments),

It would also help to know what type of hardware you would be using.

ALSO...

When you say 54mb's is the net bit rate, this is actually far from the truth, 54mb's would actually be the GROSS bit rate.
(This wouldn't even touch the maximum burstable bit rate unfortunately)

Let me know your thoughts.

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mattix mattix
 
March 29, 2009 03:48 AM
Hi xds,

Thanks for all your input so far!

I think we might be thinking of two different things.

I am wondering how to determine the purely theoretical bitrate of the different modes. Since this is theory only I think hardware and environment would be irrelevant (we can assume the conditions are ideal).

The method might not be a simple formula but I am wondering how the bitrate of 54mbps at the physical layer for example is derived based on the characteristics of the 802.11 mode (frequency, modulation, etc).

For instance, how does one come to the conclusion that the bitrate for 802.11b is 11Mbps and 802.11n is 300Mbps/600Mbps based on the theory alone. What combination of characterstics are considered when determining the bitrate at which a given mode can achieve.

Thanks alot,
MattiX

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