4QAM.rar_4QAM_4qam解调

#include<stdlib.h> #include<stdio.h> #include<math.h> #define pi 3.1415926535897931 #define SNR 21 #define M 2 FILE *file; int N=int(2e6),dtc_s,er_s,i,j,k,dtc_i,dtc_q; double m=double(RAND_MAX)/2.0; double d,dic,I,Q,min,a,b,w,x,y,E_N,src_s; double ps[SNR],map[M]; void main() { for(i=0;i<SNR;i++) { er_s=0; E_N=pow(10,double(i)/10.); d=sqrt(2*E_N/21); //定義信號位置 map[0]=-1*d; map[1]=d; // 利用Uniform R.V.來決送那一個SYMBOL for(j=0;j<N;j++) { src_s=double(rand())/(RAND_MAX+0.01); src_s=src_s*4; // 產生GAUSSIAN R.V. star: a=double(rand())/m-1; b=double(rand())/m-1; w=a*a+b*b; if(w < 1 ) { x=a*sqrt(-2*log(w)/w); y=b*sqrt(-2*log(w)/w); } else goto star; //不同symbol在I Q Channel產生不同的信號 // AWGN CHANNEL SIMULATION I = map[int(src_s)%2] + x; Q = map[int(src_s)/2] + y; // detection Signal //計算接受I Channel信號和各點之間的距離，用來判斷是那一個symbol。 min=100; for(k=0;k<M;k++) { dic = fabs(I - map[k]); if(min > dic) { min=dic; dtc_i=k; } } //計算接受到Q Channel信號和各點之間的距離，用來判斷是那一個symbol。 min=100; for(k=0;k<M;k++) { dic = fabs(Q - map[k]); if(min > dic) { min=dic; dtc_q=k; } } // I Q Chennel 的信號合成一個4-ary QAM symbol dtc_s = 2*dtc_q+dtc_i; if(dtc_s != int(src_s) ) er_s++; } // 計算 BER printf("\n%d ",er_s); ps[i]=double(er_s)/double(N); } //結果放入MATLAB的M-file中 file = fopen("C:\\MATLAB6p5\\work\\qam4.m","w"); fprintf(file,"a = ["); for(i=0;i<SNR;i++) fprintf(file,"%.16f\n",ps[i]); fprintf(file,"]';\n"); fprintf(file,"snr1=0:%d;\n",SNR-1); fprintf(file,"semilogy(snr1,a,'k');hold on\n"); fclose(file); }