Rec618_10.rar_ITU模型_matlab 信道建模_rain attenuation_信道衰减_衰减

% Rec618_10 % reccomendation ITU-R 618-10 % Average Annual rain fade distribution on earth-Space Links function Ap= Rec618_10(p) % INPUTS %phi=0.6894;% phi = latitude in radians %phi=0.7931; %哈尔滨地区的纬度 phi=0.4028;%guangzhou %phi=0.5627; h_s=0.055;% h_s = height of Earth station in km theta=0.2744;% theta = elevation angle in radians %h_r=3.7375;% h_r = rain height in km %h_r=3.2920; % 哈尔滨 h_r=3.6462;%guangzhou %h_r=3.9027; Freq=30;% Freq = frequency in GHz %gammaR=4.0293; %gammaR=6.0905; %gammaR=8.6853;% guangzhou gammaR = specific attenuation of r01 gammaR=14.6506; % p = time percentages % OUTPUT % Ap = average annual fade exceeded at given percentage Rad2Deg = 180/pi; % conversin factor from radians to degrees phi_deg = phi*Rad2Deg; theta_deg = theta*Rad2Deg; % Step 1 % rain height is an input % Step 2 if theta_deg > 5 L_s = (h_r-h_s)/sin(theta); % path length through rain in km else stop end % Step 3 L_G = L_s * cos(theta); % horizontal projection % Step 4 % 0.01% exceeded rain rate is an input %Step 5 % 0.01% exceeded specific attenuation is an input % Step 6 % horizontal reduction factor r01 = 1/( 1 + 0.79*sqrt( L_G*gammaR/Freq ) - 0.38*( 1-exp(-2*L_G) ) ); % Step 7 sqiggle = atan( (h_r-h_s)/(L_G*r01) ); if sqiggle>theta L_R = L_G*r01/cos(theta); else L_R = (h_r - h_s)/sin(theta); end if abs(phi_deg)<36 chi = 36-abs(phi_deg); else chi = 0; end %v01 = 1/( 1 + sqrt(sin(theta))*( 31*(1-exp(-(theta_deg/(1+chi)))*sqrt(L_R*gammaR)/Freq^2 ) - 0.45) ); v01 = sqrt(L_R*gammaR)/Freq^2; v01 = 31*( 1-exp( -( theta_deg/( 1+chi ) ) ) )*v01 - 0.45; v01 = 1 + sqrt( sin( theta ) )*v01; v01 = 1/v01; % Step 8 L_E = L_R*v01; %Step 9 A01 = gammaR*L_E; % Step 10 %NOTE different coefficients for p>1% or constraints on latitude and %elevation beta = -0.005*(abs(phi_deg)-36) + 1.8 - 4.25*sin(theta); for i=1:5000 if p(i)>=1 || abs(phi_deg)>=36 beta = 0.0; end if p(i)<1 && abs(phi_deg)<36 && theta_deg>=25 beta = -0.005*(abs(phi_deg)-36); end Ap(i) = A01* (p(i)/0.01).^(-(0.655+0.033*log(p(i))-0.045*log(A01)-beta*(1-p(i))*sin(theta))); end