A problem about subcarrier spacing of ofdm

Hello!

Recently I am working on a project of OFDM simulation. When I want to simulate the influence of subcarrier spacing (such as 10kHz, 15 kHz and 20kHz ), I find that that there is no code in my project that show the influence of subcarrier spacing. To be more specific, the exact code of my project is :

y=ifft(x,Nfft); % where x is the modulated signal and Nfft is the number of Nfft

Then I pass the signal to a fading channel and do the rest. So I find there is no parameter that is related to the subcarrier sapcing. So how can I show the influence of subcarrier spacing, or I just misunderstood the code of OFDM simualtion.

Thanks!

Answer 1

[William Rose]

@lc,

The error you report is because the variable x has not been defined. You will need to provide more context in order to receive more detailed assistance.

[lc]

Thanks for your answer. But this code is just an example and what i really care about is how to show the influence of different subcarrier spacing. Can u help me with that?

[William Rose]

@lc, there are multiple potential influences of different subcarrier spacing. Of course you can fit more subcarriers into a given amount of total bandwidth, if the subcarrier spacing is narrower. Or, equivalently, you can transmit the same number of subcarriers with a smaller total bandwidth, if the subcarrier spacing is narrower. But the system noise sensitivity (including multipath interference sensitivity) is likely to be greater when the subcarrier spacing is narrower, so you can expect high bit error ratios, if other aspect s of the system performance are kept constant. To illustrate this, you will want to simulate signal transmission and reception in the presence of noise.

You might want to check out this or this.