qpsk.zip_QPSK_qpsk c code

#include <stdio.h> #include <stdlib.h> #include <math.h> #define num 1000 #define iter_num 1000 #define EbNo_start 0 #define EbNo_end 20 #define pi 3.141592 double awgn(double power); void main() { int i=0,iter=0,db=0; double qpsk_ber=0, a=1/sqrt(2); FILE *fp1 = fopen("QPSK_BER.txt", "wt"); double *bit_stream = (double *)calloc(num, sizeof(double)); double *QPSK_symbol_re = (double *)calloc(num, sizeof(double)); double *QPSK_symbol_im = (double *)calloc(num, sizeof(double)); double *signal = (double*)calloc(num, sizeof(double)); for(db=EbNo_start; db<EbNo_end; db++) { double error=0; double noise_power=pow(10,-1*(double)db/10)/2; printf("EbNo : %d [dB]\t",db); for(iter=0;iter<iter_num;iter++){ for(i=0;i<num;i++) { bit_stream[i]=rand()%2; } for(i=0;i<num/2;i++){ if(bit_stream[2*i]==0&&bit_stream[2*i+1]==0){ QPSK_symbol_re[i]=a+awgn(noise_power)/sqrt(2); QPSK_symbol_im[i]=a+awgn(noise_power)/sqrt(2); } else if(bit_stream[2*i]==0&&bit_stream[2*i+1]==1){ QPSK_symbol_re[i]=-a+awgn(noise_power)/sqrt(2); QPSK_symbol_im[i]=a+awgn(noise_power)/sqrt(2); } else if(bit_stream[2*i]==1&&bit_stream[2*i+1]==1){ QPSK_symbol_re[i]=-a+awgn(noise_power)/sqrt(2); QPSK_symbol_im[i]=-a+awgn(noise_power)/sqrt(2); } else if(bit_stream[2*i]==1&&bit_stream[2*i+1]==0){ QPSK_symbol_re[i]=a+awgn(noise_power)/sqrt(2); QPSK_symbol_im[i]=-a+awgn(noise_power)/sqrt(2); } } for(i=0;i<num/2;i++){ if(QPSK_symbol_re[i]>0 && QPSK_symbol_im[i]>0){ signal[2*i]=0; signal[2*i+1]=0; } else if(QPSK_symbol_re[i]<=0 && QPSK_symbol_im[i]>0){ signal[2*i]=0; signal[2*i+1]=1; } else if(QPSK_symbol_re[i]<=0 && QPSK_symbol_im[i]<=0){ signal[2*i]=1; signal[2*i+1]=1; } else if(QPSK_symbol_re[i]>0 && QPSK_symbol_im[i]<=0){ signal[2*i]=1; signal[2*i+1]=0; } } for(i=0;i<num;i++){ if(!(bit_stream[i]-signal[i]==0)) error++; } if( iter % (iter_num/10) ==0 ) printf(">"); } qpsk_ber = (double)error/(num*iter_num); printf("\t%lf\n",qpsk_ber); fprintf(fp1,"%lf\n",qpsk_ber); } fclose(fp1); } double awgn(double power) { double x=0,tmp1,tmp2; tmp1=(double)rand()/(double)RAND_MAX; while(tmp1==0) tmp1=(double)rand()/(double)RAND_MAX; tmp2=(double)rand()/(double)RAND_MAX; x=sqrt((-2*log(tmp1))) *cos(2*pi*tmp2) * sqrt(power); return x; }