Baseband simulation system experiment of 4pam in Gaussian channel and Rayleigh channel

1、 System diagram

2、 Code

clear all
close all
clc
N = 10000;   % Number of bits 
SNR=0:10;   %SNR The scope of the 
EbN0 = 10.^(SNR/10);
err_num=zeros(1,length(SNR)); %  error bit Number 
simu_ber = zeros(1,length(SNR));     %  Simulation bit error rate 
theory_berAWGN = zeros(1,length(SNR));   %  Theoretical bit error rate 
theroy_berRaliy = zeros(1,length(SNR));   %  Theoretical bit error rate 
R=raylrnd(0.5,1,N);      % Generate Rayleigh signal 
M = 4;% Hexadecimal number 
graycode = [0,1,2,3];% gray mapping 
send_bit = randsrc(1,N,[0:3]);
send_bit2 = graycode(send_bit+1); % Gray code 
send_bit3 = pammod(send_bit2,M);%PAM modulation 

msg_tx = real(send_bit3);
hR = send_bit3.*R; % Rayleigh distribution 
pow_msg=norm(msg_tx)^2/length(msg_tx); % Signal symbol power Es
for k=1:length(SNR)   
    sigma=sqrt(pow_msg/(2*10^(SNR(k)/10))); % Noise variance 
    msg_rx_awgn=msg_tx+sigma*randn(1,N);% adopt AWGN channel 
    msg_rx_raily=awgn(hR,SNR(k),'measured');
    %4PAM  demodulation  
    dePAM_awgn = pamdemod(msg_rx_awgn,M);%PAM demodulation 
    decPAM_awgn = graycode(dePAM_awgn+1);% demapping 
    dePAM_Raily = pamdemod(msg_rx_raily,M);
    decPAM_Raily = graycode(dePAM_Raily+1);

 
    [~,BER(k)] = biterr(send_bit, decPAM_awgn, log2(M));   % Calculation AWGN channel BER
    [ ~,BER1(k)] =biterr(send_bit,decPAM_Raily,log2(M));   % Calculate Rayleigh fading +AWGN channel BER
    [ ~,SER(k)] = symerr(send_bit, decPAM_awgn);            % Calculation AWGN channel SER
    [~,SER1(k)] = symerr(send_bit, decPAM_Raily);          % Calculate Rayleigh fading +AWGN channel SER

    theory_ser(k) = 1.5*qfunc(sqrt(0.4*EbN0(k))); %  Theoretical symbol error rate 
    theory_ber(k) = (2*(M-1)/M)*qfunc(sqrt(6*EbN0(k)/(M^2-1)));%  Theoretical bit error rate 
    
end
figure
semilogy(SNR,BER,'-ro',SNR,SER,'-r*',SNR,BER1,'-b.',SNR,SER1,'-b^',SNR,theory_ser,'o-',SNR,theory_ber,'-sg')  ;     % Draw BER and SER along with SNR The curve of change 
legend('AWGN channel BER','AWGN channel SER','Rayleigh Decline +AWGN channel BER','Rayleigh Decline +AWGN channel SER',' Theoretical symbol error rate ',' Theoretical bit error rate ');
title('4PAM stay AWGN and Rayleigh Performance in fading channels ');
xlabel(' Signal-to-noise ratio （dB）');
ylabel(' Symbol error rate and bit error rate ');

%% Draw a constellation 
scatterplot(send_bit3);
title(' Modulation signal constellation ');
scatterplot(msg_rx_awgn);
title('AWGN Received signal constellation ');
scatterplot(msg_rx_raily);
title('Raily Received signal constellation ');

3、 experimental result