multipathfadingchannel.m

文件中包括括了Multipath fading Channel和RAleigh Fading Channel 的MATLAB实现方式

% Simulation of multipath fading Channel
% Observe the response of multipath fading channel to the pulses in time and freq domain

subplot(1,1,1)  % Create axes in tiled positions (m,n,p), breaks the Figure window 
                % into an m-by-n matrix of small axes, selects the p-th axes for 
                % for the current plot, and returns the axis handle.   
% Initializations
fs = 1e7;   % fs   - sampling rate (e.g., 1e7 for 10000KHz), 1/fs=1e-7 second
f0=1e9;     % f0   - carrier frequency (e.g., 1e9 for 1GHz)
v=100;      % v    - vehicle speed in km/h (determines doppler frequency)

tt = 0:1/fs:4.1e-3;     % time range start 0s until 4.1e-3s=4.1ms step 1/fs=1e-7 second (41001 points)

% input signal (an impulse once per millisecond)
ss = zeros(size(tt));
Delta = 1e-3;                  
DeltaS = round(Delta*fs);       % Round towards nearest integer, one pulse in every 10000 samples
ss(1:DeltaS:length(ss)) = 1;    % Prepare input signal s_in (5 pulses) to be fed into the channel, 

% Channel output rr: invoke fading multipath channel simulator
rr = RayleighFadingNoise2_GSM(ss, f0, fs, v, 1);  % seed=1 - seed for random number generator

% Results:
% Multipath due to impulse at t=0
stem(1e6*tt(1:60), real(rr(1:60)),'b'); % STEM(X,Y) plots the discrete data sequence Y versus X.
xlabel('Time (\mus)')
title('Channel response for \delta(t)')

pause

% Fouriertransform of response to first pulse
ff=0:10e3:5e6;
RR = zeros(size(ff));
for nn=1:60
    RR = RR + rr(nn)*exp(-j*2*pi*ff*nn/fs);
end
semilogy(ff/1e3, abs(RR))       % the same as PLOT() except a logarithmic (base 10) scale for the Y-axis.
xlabel('Frequency (KHz)')
ylabel('|R(f)|')
grid;

pause

% Time/freq responses to the 5 pulses
for kk=1:5              
    subplot(5,2,2*kk-1)
    stem(1e6*tt((1:60)+(kk-1)*DeltaS), real(rr((1:60)+(kk-1)*DeltaS)),'b');
    xlabel('Time (\mus)')
    title(sprintf('Impulse at t= %d ms',kk))
    
    subplot(5,2,2*kk)
    RR = zeros(size(ff));
    for nn=1:60
        RR = RR + rr(nn+(kk-1)*DeltaS)*exp(-j*2*pi*ff*nn/fs);
    end
    semilogy(ff/1e3, abs(RR))
    xlabel('Frequency (KHz)')
    ylabel('|R(f)|')
    grid;
end