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CDMA_ejemplo-utf8.m
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CDMA_ejemplo-utf8.m
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%% Ejemplo CDMA
clc
clear all
close all
% Parámetros
n_data = 3; % nro bits de datos
n_PN = 30; % nro de bits secuencia pseudo aleatoria
n = 2; % cantidad de usuarios simultaneos
%% Generacion de datos
% generacion de datos y las secuencias pseudo aleatorias para la
% codificacion
data = randi([0 1],n_data,n);
PN = randi([0 1],n_PN,n);
for i = 1:n
disp(strcat("Data usuario ",i))
transpose(data(:,i))
end
for i = 1:n
disp(strcat("Secuencia pseudoaleatoria usuario ",i))
transpose(PN(:,i))
end
%% Codificacion
%
% codificacion
data = 2*data-1;
for i = 1:n
signal(:,i) = kron(data(:,i),PN(:,i));
end
signal
%%
% concatena la secuencia PN n_data veces
PN_long = repmat(PN,[n_data 1]);
% repite los datos para graficar
PN_mat_plot = repelem(PN_long,100,1);
data_plot = repelem(data,100,1);
signal_plot = repelem(signal,100,1);
L=length(PN_mat_plot);
for user = 1:n
figure
subplot(3,1,1)
plot(data_plot(:,user),'linewidth',3)
title('data')
% configs grafico
set(gca,'XTick',0:n_PN*100:L);
set(gca,'XTickLabel',0:n_data);
subplot(3,1,2)
plot(PN_mat_plot(:,user),'linewidth',3)
title('secuencia pseudo aleatoria')
% configs grafico
set(gca,'XTick',0:n_PN*100:L);
set(gca,'XTickLabel',0:n_data);
subplot(3,1,3)
plot(signal_plot(:,user),'linewidth',3)
title('senial codificada')
% configs grafico
set(gca,'XTick',0:n_PN*100:L);
set(gca,'XTickLabel',0:n_data);
title(strcat('Usuario ', user))
end
%% Combinacion de seniales
transmittesr_signal = sum(signal,2);
transmitter_signal_plot = sum(signal_plot,2);
figure
subplot(3,1,1)
plot(signal_plot(:,1),'linewidth',3)
title('senial a codificada user 1')
% configs grafico
set(gca,'XTick',0:n_PN*100:L);
set(gca,'XTickLabel',0:n_data);
subplot(3,1,2)
plot(signal_plot(:,2),'linewidth',3)
title('senial a codificada user 2')
% configs grafico
set(gca,'XTick',0:n_PN*100:L);
set(gca,'XTickLabel',0:n_data);
subplot(3,1,3)
plot(transmitter_signal_plot,'linewidth',3)
title('senial atransmitir')
% configs grafico
set(gca,'XTick',0:n_PN*100:L);
set(gca,'XTickLabel',0:n_data);
%%
% espectros
f_data = -pi:2*pi/length(data):pi-2*pi/length(data);
f_signal = -pi:2*pi/length(signal):pi-2*pi/length(signal);
figure
subplot(3,1,1)
stem(f_data,abs(fftshift(fft(data(:,1))))/length(data))
xlim([-pi pi])
subplot(3,1,2)
stem(f_signal,abs(fftshift(fft(signal(:,1))))/length(signal))
xlim([-pi pi])
subplot(3,1,3)
stem(f_signal,abs(fftshift(fft(signal(:,2))))/length(signal))
xlim([-pi pi])
%% Decodificacion
%
for user = 1:n
decoded_signal(:,user) = (reshape(transmittesr_signal,[n_PN n_data])'*PN(:,user));
recovered_signal(decoded_signal(:,user) > 0) = 1;
recovered_signal(decoded_signal(:,user) <= 0) = 0;
%plots
decoded_signal_plot = repelem(decoded_signal(:,user),500,1);
recovered_signal_plot = repelem(recovered_signal',500,1);
figure
subplot(4,1,1)
plot(transmitter_signal_plot,'linewidth',3)
title('senial recibida')
% configs grafico
set(gca,'XTick',0:n_PN*100:L);
set(gca,'XTickLabel',0:n_data);
subplot(4,1,2)
plot(PN_mat_plot(:,user),'linewidth',3)
title('secuencia pseudo aleatoria')
% configs grafico
set(gca,'XTick',0:n_PN*100:L);
set(gca,'XTickLabel',0:n_data);
subplot(4,1,3)
plot(recovered_signal_plot,'linewidth',3)
title('senial decodificada')
% configs grafico
set(gca,'XTick',0:n_PN*100:L);
set(gca,'XTickLabel',0:n_data);
subplot(4,1,4)
plot(data_plot(:,user),'linewidth',3)
title('data original')
% configs grafico
set(gca,'XTick',0:n_PN*100:L);
set(gca,'XTickLabel',0:n_data);
end