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clear all;
close all;
c = 3e8;
% Excess taps delay (according to 3GPP TS 36.104 Annex B.2)
delays_pedestrianEPA = [0 30e-9 70e-9 90e-9 120e-9 190e-9 410e-9];
delays_vehicularEVA = [0 30e-9 150e-9 310e-9 370e-9 710e-9 1090e-9 1730e-9 2510e-9];
delays_urbanETU = [0 50e-9 120e-9 200e-9 230e-9 500e-9 1600e-9 2300e-9 5000e-9];
Td = 100/c;
% Realtive power of taps (according to 3GPP TS 36.104 Annex B.2)
power_pedestrianEPA = [0.0 -1.0 -2.0 -3.0 -8.0 -17.2 -20.8];
power_vehicularEVA = [0.0 -1.5 -1.4 -3.6 -0.6 -9.1 -7.0 -12.0 -16.9];
power_urbanETU = [-1.0 -1.0 -1.0 0.0 0.0 0.0 -3.0 -5.0 -7.0];
% DL EARFCN=500
% fc = 2160e6; %
% UL EARFCN=18100
fc = 1930e6;
lambda = c/fc;
v_km_h = 3.0; % speed of mobile node
v_m_s = v_km_h / 3.6;
fd = v_m_s / lambda; % doppler shift
% when working with an FFT, the normalized frequency w is
% w = 2 * pi * (f/fs) * t
% hence the max normalized frequency w=2*pi corresponds to f = fs,
% hence fs is also the max frequecy of our PowerSpectralDensity
fs = 20e6;
% sampling period must be determined corresponding to the sampling
% frequency, because of the properties of an FFT
% in other words, if ts = 1/fs, then the samples of the FFT will be
% spaced by fs (which is what we want)
ts = 1/fs; % sampling period (i.e., 1 subframe duration)
% create the channel object
c = rayleighchan(ts, fd, delays_pedestrianEPA, power_pedestrianEPA);
%c = rayleighchan(ts, fd, delays_vehicularEVA, power_vehicularEVA);
%c = rayleighchan(ts, fd, delays_urbanETU, power_urbanETU);
%c.StorePathGains = 1;
c.ResetBeforeFiltering = 0;
c.NormalizePathGains = 1;
TTI = 0.001;
% number of samples of one channel realization
numSamples = TTI / ts;
% total trace duration in s
traceDuration = 10.0;
numRBs = 100;
sig = zeros(numSamples, 1); % Signal
sig(1) = 1; % dirac impulse
[psdsig,F] = pwelch(sig,[],[],numRBs,fs,'twosided');
for ii=1:round((traceDuration/TTI))
% y is the frequency response of the channel
y = filter(c,sig);
% [Pxx,F] = PWELCH(X,WINDOW,NOVERLAP,NFFT,Fs) returns a PSD computed as
% a function of physical frequency (Hz). Fs is the sampling frequency
% specified in Hz. If Fs is empty, it defaults to 1 Hz.
%
% F is the vector of frequencies at which the PSD is estimated and has
% units of Hz. For real signals, F spans the interval [0,Fs/2] when NFFT
% is even and [0,Fs/2) when NFFT is odd. For complex signals, F always
% spans the interval [0,Fs).
[psdy,F] = pwelch(y,[],[],numRBs,fs);
%% the gain in frequency is obtained by dividing the psd of the received signal
%% by the psd of the original signal. Note that the psd of the original
%% signal is constant in frequency (since the transform of a delta is a
%% constant)
ppssdd(:,ii) = psdy ./ psdsig;
% this to plot
% figure;
% PWELCH(y,[],[],numRBs,fs);
% alternative plot
%figure;
%plot(F, 10.*log10(ppssdd(:,ii)));
end
surf(10.*log10(ppssdd));
title ('Fading Pedestrian EPA 3kmph');
%title ('Fading Vehicular EVA 60kmph');
%title('Fading Urban ETU 0 kmph');
%title('Fading Urban ETU 3 kmph');
%title('Fading Urban ETU 30 kmph');
tag = 'EPA_3kmph';
%tag = 'EVA_60kmph';
%tag = 'ETU_0kmph';
%tag = 'ETU_3kmph';
%tag = 'ETU_30kmph';
ylabel ('RB index');
xlabel ('time [ms]');
zlabel ('Amplitude [dB]');
%FILE GENERATION
TAG = upper(tag);
len = round((traceDuration/TTI));
file = fopen(strcat('fading_trace_',tag,'.fad'),'at');
for j=1:numRBs
for s=1:len
fprintf(file, '%g ',10.*log10(ppssdd(j, s)));
end
fprintf(file, '\n');
end
fclose(file);
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