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Help : Sampling Factor in Wimax(Please)

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srksp

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sampling factor

I would be very much pleased if any one could explain me what is meant by sampling factor and how is it calculated in Wimax. In the standard they are telling to take various values like 8/7, 28/25 for n(i.e sampling factor). I want to know how can we get that factor. I know that it depends on number of subcarriers and bandwidth but i dont know how actually they arrived at that factor. For your reference i am pasting the line as given in the 802.16e standard.

"n: Sampling factor. This parameter, in conjunction with BW and Nused determines the subcarrier spacing, and the useful symbol time. This value is set as follows: for channel bandwidths that are a multiple of 1.75 MHz then n = 8/7 else for channel bandwidths that are a multiple of any of 1.25, 1.5, 2 or 2.75 MHz then n = 28/25 else for channel bandwidths not otherwise specified then n = 8/7."
 

wimax sampling factor

hey even i have the same query .. lets c anybody can lend a helping hand ..
 

sampling factor definition

We can start a new thread for the queries in WiMAX network.
i also have few questions and it will be good if we could rope in some enlightened guys on the subject please

Sidd
 

sampling factor

It is said that WiMax (IEEE 802.16) specification is not well written.

In OFDM systems, RF BW usually is smaller than FFT BW (Nfft * subcarrier spacing). E.g., 802.11a, RF BW=17.6MHz (-3dBc) while FFT BW is 20 MHz.

My understanding is the sampling factor in WiMax FFT BW to RF BW ratio. In the case of 802.11a, the sampling factor is 20/17.6 = 1.136. I hope my understanding is correct.
 

    srksp

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wimax sampling frequency

The bandwidth is an artificial number used to describe the system parameter. As stated in the spec the sampling frequency is

fs=8000*floor(n*BW/8000); n=8/7, 144/125 BW[Hz]

take BW=10MHz you will get fs=11.424MHz

I think the truncation to 8kHz in the above formular has to do with a time frame definition from that sampling frequency. But I am not shure.

The factor n=28/25 is not know to me and 16d and Mobile WiMAX is using 8/7 only
 

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