多径多普勒信道模型_信道模型_多径信道_多普勒_

clear all; N=20 ;% number of multipath arrivals a=rand(1,N); %amplitude tau=rand(1,N); %arrival time f_d=0.01 shift=rand(1,N)*2*f_d-f_d; %Doppler shifts f=10; % the frequency of the transmitted time harmonic signal f_shift=f+shift; t=[0:0.01:50]; n=1; y_d_t=sum(a(n)*exp(-j*2*pi*f*tau(n)))*exp(j*2*pi*(f_shift(n))*t); for n=2:N y_d_t=y_d_t+a(n)*exp(-j*2*pi*f*tau(n))*exp(j*2*pi*(f_shift(n))*t); %received signal end subplot(2,2,1) plot(t,y_d_t) xlabel('time, sec') ylabel('f_D=0.01') N=20 ;% number of multipath arrivals a=rand(1,N); %amplitude tau=rand(1,N); %arrival time f_d=0.05 shift=rand(1,N)*2*f_d-f_d; %Doppler shifts f=10; % the frequency of the transmitted time harmonic signal f_shift=f+shift; t=[0:0.01:50]; n=1; y_d_t=sum(a(n)*exp(-j*2*pi*f*tau(n)))*exp(j*2*pi*(f_shift(n))*t); for n=2:N y_d_t=y_d_t+a(n)*exp(-j*2*pi*f*tau(n))*exp(j*2*pi*(f_shift(n))*t); %received signal end subplot(2,2,2) plot(t,y_d_t) xlabel('time, sec') ylabel('f_D=0.05') N=20 ;% number of multipath arrivals a=rand(1,N); %amplitude tau=rand(1,N); %arrival time f_d=0.1 shift=rand(1,N)*2*f_d-f_d; %Doppler shifts f=10; % the frequency of the transmitted time harmonic signal f_shift=f+shift; t=[0:0.01:50]; n=1; y_d_t=sum(a(n)*exp(-j*2*pi*f*tau(n)))*exp(j*2*pi*(f_shift(n))*t); for n=2:N y_d_t=y_d_t+a(n)*exp(-j*2*pi*f*tau(n))*exp(j*2*pi*(f_shift(n))*t); %received signal end subplot(2,2,3) plot(t,y_d_t) xlabel('time, sec') ylabel('f_D=0.1') N=20 ;% number of multipath arrivals a=rand(1,N); %amplitude tau=rand(1,N); %arrival time f_d=0.5 shift=rand(1,N)*2*f_d-f_d; %Doppler shifts f=10; % the frequency of the transmitted time harmonic signal f_shift=f+shift; t=[0:0.01:50]; n=1; y_d_t=sum(a(n)*exp(-j*2*pi*f*tau(n)))*exp(j*2*pi*(f_shift(n))*t); for n=2:N y_d_t=y_d_t+a(n)*exp(-j*2*pi*f*tau(n))*exp(j*2*pi*(f_shift(n))*t); %received signal end subplot(2,2,4) plot(t,y_d_t) xlabel('time, sec') ylabel('f_D=0.5')