4 семестр ИКТ 6 вариант / ЛР4 СПВТ

Лабораторная работа №4

Задание 1

clear all;clc;

close all;

N=100000;%Number of bits to transmit

EbN0dB = -4:2:6; % Eb/N0 range in dB for simulation

fc=100;%carrier frequency in Hertz

OF =8; %oversampling factor, sampling frequency will be fs=OF*fc

EbN0lin = 10.^(EbN0dB/10); %converting dB values to linear scale

BER = zeros(length(EbN0dB),1); %For BER values for each Eb/N0

a = rand(N,1)>0.5; %random bits - input to QPSK

[s,t] = qpsk_mod(a,fc,OF);%QPSK modulation

for i=1:length(EbN0dB)

Eb=OF*sum(abs(s).^2)/(length(s)); %compute energy per bit

N0= Eb/EbN0lin(i); %required noise spectral density from Eb/N0

n = sqrt(N0/2)*(randn(1,length(s)));%computed noise

r = s + n;%add noise

a_cap = qpsk_demod(r,fc,OF); %QPSK demodulation

BER(i) = sum(a~=a_cap.')/N;%Bit Error Rate Computation

end

%------Theoretical Bit Error Rate------------

theoreticalBER = 0.5*erfc(sqrt(EbN0lin));%Theoretical bit error rate

%-------------Plot performance curve-----------------------

figure;

semilogy(EbN0dB,BER,'k*','LineWidth',1.5); %simulated BER

hold on;

semilogy(EbN0dB,theoreticalBER,'r-','LineWidth',1.5);

title('Probability of Bit Error for QPSK modulation');

xlabel('E_b/N_0 (dB)');ylabel('Probability of Bit Error - P_b');

legend('Simulated', 'Theoretical');grid on;

Задание 2

clear

clc

close all;

nSym=2.4*10^6

EbN0dB = -4:2:6;

MOD_TYPE='FSK';

arrayOfM=[2,4,8,16,32];

COHERENCE = 'noncoherent'

plotColor =['b','g','r','c','m','k']; p=1;

legendString = cell(1,length(arrayOfM)*2);

for M = arrayOfM

k=log2(M);

EsN0dB = 10*log10(k)+EbN0dB;

SER_sim = zeros(1,length(EbN0dB

d=ceil(M.*rand(1,nSym));

s=modulate(MOD_TYPE,M,d,COHERENCE);

for i=1:length(EsN0dB)

r = add_awgn_noise(s,EsN0dB(i));

dCap = demodulate(MOD_TYPE,M,r,COHERENCE);

SER_sim(i) = sum((d~=dCap))/nSym;

end

SER_theory = ser_awgn(EbN0dB,MOD_TYPE,M,COHERENCE);

semilogy(EbN0dB,SER_sim,[plotColor(p) '*']);

hold on;

semilogy(EbN0dB,SER_theory,plotColor(p));

legendString{2*p-1}=['Sim ',num2str(M),'-',MOD_TYPE];

legendString{2*p}=['Theory ',num2str(M),'-',MOD_TYPE];

p=p+1;

end

legend(legendString);

xlabel('Eb/N0(dB)');

ylabel('SER (Ps)');

title(['Probability of Symbol Error for M-',MOD_TYPE,' over AWGN']);