蒙特卡罗模拟QPSK传输噪声仿真Matlab代码.rar

% *************** Simulation BER of QPSK transmission over noise *********% % with using Monte Carlo simulation % ********************* Initialization ***********************************% clc; clear all; close all; loop=1; % Monte Carlo M=1000000; % Frame length (x_1 x_2 ... x_M) SNRdB=-10:10; % SNR in dB SNR=10.^(SNRdB/10); Rate= zeros(1, length(SNRdB)); % % ********************* Transmitter **************************************% for dB= 1: length(SNRdB) % start looping by SNR dB for lp= 1: loop, % start looping of frame data % ********************* QPSK signal generation ***************************% x_inp_I=sign(rand(M,1)- 0.5); % 1 or -1 for inphase signal x_inp_Q=sign(rand(M,1)- 0.5); % 1 or -1 for guadrature signal x_inp=x_inp_I+i*x_inp_Q; % 1+j=00, -1+j=01, -1-j=10, 1-j=11 x_inp=(1/sqrt(2))*x_inp; % normalization % ********************* Channel ******************************************% N0=1./SNR(dB); sigma(dB)=sqrt(N0/2); noise=(1/sqrt(2))*(sigma(dB)*randn(M,1)+i*sigma(dB)*randn(M,1)); y_channel=x_inp+noise; % Additive White Guassiann Noise (AWGN) % ********************* Receiver *****************************************% y=y_channel; x_out_I= sign(real(y)); % x_out_Q= sign(imag(y)); % x_out=x_out_I+i*x_out_Q; % ********************* Bit Error Rate (BER) calulation ******************% [err, rate]= symerr([x_inp_I;x_inp_Q], [x_out_I;x_out_Q]); Rate(dB)= Rate(dB) + rate; end % end for loop Rate(dB)= Rate(dB)/loop; % Average value over Monte Carlo simulation % loop end % end Monte Carlo % ********************* Plot the simulation result ***********************% f1 = figure(1); set(f1,'color',[1 1 1]); semilogy(SNRdB,Rate, 'b') hold on; BER_th=(1/2)*erfc(sqrt(SNR)); % theoritical calculation for BER semilogy(SNRdB,BER_th,'r-o'); hold on; axis([-10 10 0.000001 1.2]); xlabel( 'Signal-to-Noise Ratio (SNR)') ylabel( 'Bit Error Rate (BER)') title('Simulation QPSK transmission over noise'); legend('BER simulation','BER calculation') grid on;