# Tag Info

1

The channel which you have created is having 4-Taps and all taps are one after the other, meaning roughly there are 4 multi-paths and they are very close to each other. How close depends on what is the Sub-Carrier Spacing you would have assumed. Anyway, the point is only 3 samples of Cyclic Prefix would be enough and even with 0 or 2 samples of CP will not ...

0

It is irrelevant what carrier frequency is used. The bandwidth used is determined by the symbol rate, and the bandwidth efficiency is determined by how many bits we can map to each symbol. The actual bandwidth is further modified by any pulse shaping that would typically be used to constrain the spectrum, but as a guide consider that the Fourier Transform of ...

1

I see how you added the carrier by multipying by $1 + 0.5cos(2\pi f t)$ (or you used sine, wouldn't change it), and that approach seems fine to me. It looks like you do actually see the carrier in your plot! What I see from your plot does appear to be a signal at +/-25 Hz which is what we would expect to see for $cos(2\pi 25 t)$ (or sine if you used that) ...

1

Nothing is missing in your understanding. When we calculate power that way, it is assuming a $1 \Omega$ load and that amplitudes are given in volt, but almost nobody ever says that even in textbooks. Unless it is explicitly stated otherwise, I think it is safe to assume this.

2

So, I myself have taught based on material that uses that scheme, "P/S" and "S/P" after and before the transforms. Personally, it's nonsense. What the author tries to say is: The IFFT is a mapping of sample vectors to vectors. So, you need a vector as input, not a stream of samples. What they instead say is: We use the terminology from very basic ...

5

In digital communications, information is transmitted in quantized form. We are constrained to transmit items that belong to a finite, discrete set. The items are called "symbols", and the set is called a "constellation". The symbols may be transmitted by changing a signal's frequency, phase and/or amplitude. As an example, pulse amplitude modulation (PAM) ...

1

OP here. (Looks like I changed my name from Oscar to Jerry.) Sorry for letting this go for so long. The correct answer to my question is that the use of the naked delta—including under non-limiting integrals—is a shorthand. Whenever you see a naked delta, you may replace it with some suitable limiting integral of a unit-area function that tends to zero ...

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