%uwb_ch calculates the tap amplitudes and tap delays for a UWB channel%according to the modified S-V model%cm : Target Channel Characteristic% m : Number of Clusters% n : Number of rays within each cluster%function [h_val,Del]=uwb_ch(cm,m,n)clear all;cm=1;m=1;n=20;% Modified S-V Channel Model Parametersif cm==1        V=0.0233e9;%Cluster Arrival Rate    v=2.5e9;%Ray Arrival Rate    D=7.1;%Cluster Decay Factor    d=4.3;%Ray Decay Factor    nlos=0;else if cm==2        V=0.4e9;%Cluster Arrival Rate        v=0.5e9;%Ray Arrival Rate        D=5.5;%Cluster Decay Factor        d=6.7;%Ray Decay Factor        nlos=1;            else if cm==3                        V=0.0667e9;%Cluster Arrival Rate            v=2.1e9;%Ray Arrival Rate            D=14;%Cluster Decay Factor            d=7.9;%Ray Decay Factor            nlos=1;                    else if cm==4                                V=0.0667e9;%Cluster Arrival Rate                v=2.1e9;%Ray Arrival Rate                D=24;%Cluster Decay Factor                d=12;%Ray Decay Factor                nlos=1;            end        end    endend% Setting the values for standard dev. of fadingsstd_ln_1=10^0.34;std_ln_2=10^0.34;std_shdw=10^0.3;% initialize and precompute some thingsstd_L = 1/sqrt(2*V);      % std dev (nsec) of cluster arrival spacingstd_lam = 1/sqrt(2*v); % std dev (nsec) of ray arrival spacingm_const = (std_ln_1^2+std_ln_2^2)*log(10)/20;  % pre-compute for laterif nlos,        Tc = (std_L*randn)^2 + (std_L*randn)^2;  % First cluster random arrival    else        Tc = 0;                   % First cluster arrival occurs at time 0    end    for i=1:m        %Determine Ray arrivals for each cluster        Tr = 0;  % first ray arrival defined to be time 0 relative to cluster        ln_xi = std_ln_1*randn;   % set cluster fading (new line added in rev. 1)        for j=1:n              t_val = (Tc+Tr);  % time of arrival of this ray              mu = (-10*Tc/D-10*Tr/d)/log(10) - m_const;              ln_beta = mu + std_ln_2*randn;              pk = 2*round(rand)-1;              h_val(i,j)=pk * 10^((ln_xi+ln_beta)/20);  % signed amplitude of this ray              t_ray(i,j)=Tr;              Tr = Tr + (std_lam*randn)^2 + (std_lam*randn)^2;        end        t_clst(i)=Tc;        Tc = Tc + (std_L*randn)^2 + (std_L*randn)^2;    end     pos=sign(h_val);    H_val=pos.*h_val;    h_val=sort(H_val);    h_val=pos.*h_val;    for i=1:m        Del(i,:)=t_clst(i)+t_ray(i,:);    end