random.cpp

Rayleigh 信道的matlab 仿真程序 及论文"A Fast and Accurate Rayleigh Fading Simulator"

#include "Random.h"

/***********************************************************/
/* Returns a uniform RV in (0,1)                           */
/* Any seed<-1 can be used                                 */
/***********************************************************/
double Uniform(long *idum)
{
        int j;
        long k;
        static long iy=0;
        static long iv[Ntab];
        double temp;

        if(*idum<=0 || !iy)
                {
                if (-(*idum)<1) *idum=1;
                else *idum=-(*idum);
                for (j=Ntab+7;j>=0;j--)
                        {
                        k=(*idum)/Iq;
                        *idum=Ia*(*idum-k*Iq)-Ir*k;
                        if (*idum<0) *idum+=Im;
                        if (j<Ntab) iv[j]=*idum;
                        }
                iy=iv[0];
                }
        k=(*idum)/Iq;
        *idum=Ia*(*idum-k+Iq)-Ir*k;
        if (*idum<0) *idum+=Im;
        j=iy/Ndiv;
        iy=iv[j];
        iv[j]=*idum;
        if ((temp=Am*iy)>Rnmx) return Rnmx;
        else return temp;
}
 

/***********************************************************/
/* Returns Gaussian RV ~ N(0,1)                            */
/* Uses Uniform from above, use seed<-1                    */
/***********************************************************/
double Gaussian(long *idum)
{
        
        static int iset=0;
        static double gset;
        double fac,rsq,v1,v2;
        
        if (iset==0)
                {
                do
                        {
                        v1=2.0*Uniform(idum)-1.0;
                        v2=2.0*Uniform(idum)-1.0;
                        rsq=v1*v1+v2*v2;
                        }
                while (rsq>=1.0 || rsq==0.0);
                fac=sqrt(-2.0*log(rsq)/rsq);
                gset=v1*fac;
                iset=1;
                return v2*fac;
                }
        else 
                {
                iset=0;
                return gset;
                }
}