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the answer is actually very simple. Let us consider an IFFT size of N=32. In order to make sure that the output of the IFFT operation is real-valued (real numbers without imaginary part). y=IFFT(x) You have to follow the following arrangement to the input of IFFT operation (input is x): x(0)=0 x(N/2)=0 x(n)=conj(x(-n)) Example in Matlab: M = 16; % For 16-QAM ...


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Hermitian symmetry is "imposed" on Xk symbols by ensuring that: $$x_0 = x_{N/2} = 0, \\x_k=x_{N-k}^* \forall k\in \left(k, \frac{N}{2}\right)$$ By this definition, for $N$ odd, you can choose $\frac{N-1}{2}$ independent values of $x_k$, and for $N$ even, you can choose $\frac{N}{2} - 1$ independent values of $x_k$. So you don't choose $N$ values ...


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In order to measure the ICI power on a subcarrier x (ICI that is caused by all other subcarriers). Simply, consider an ideal system without any source of noise, keep all subcarriers turned on (activated) and turn off subcarrier x (through power loading or bit loading) so that subcarrier x does not convey any data. At the receiver, after FFT, the power on ...


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Cause I'm not familiar with CDMA, so I don't know the goodness and weakness. Well, that does give you a research direction, doesn't it? About OFDM, from my point of view, OFDM due to long symbol which can deal with multipath effect to avoid inter-symbol interference. Yes, that together with the cyclic prefix allow for point-wise de-multiplication with the ...


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it is explained that an OFDM signal is a rect function in time domain No, be careful here: each subcarrier has rect shape, so the ofdm signal is the sum of rect functions, each modulated with a different complex sinusoid, shifting it in frequency. Then it is explained that in frequency domain the subcarriers will have sinc func Exactly, each subcarrier ...


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