Question

Matlab

Explain the codes below

% Jake.m

% Generate a frequency selective fading

function [r, iout, qout] = Jake(idata, qdata, nsamp, fs, fc, NN, N1_arr, velocity, counter_arr, delay_time, attn, flat)

%****************************** variables *******************************

% idata input Ich data

% qdata input Qch data

% nsamp Number of samples to be simulated

% fs Sampling frequency (Hz)

% fc Carrier Frequency (Hz)

% NN Number of paths

% N1 Number of waves in order to generate fading

% velocity Mobile speed in Km/h

% counter Fading counter

% delay_time Delay for each fading path (ns)

% attn Attenuation level for different fading paths (dB)

% flat flat fading or not

% r Envelope of fading channel complex impulse response

% iout output Ich data

% qout output Qch data

%************************************************************************

v = velocity./3.6; % m/s

c = 3e8;

fm = fc*v/c; % Maximum doppler frequency (Hz)

delay_samp = round(delay_time.*fs.*1e-9); % normalized delay time in number of samples

total_attn = sum(10.^(-1.0.*attn./10.0)); % normalize the power

tstp = 1/fs; % minimum time resolution

iout = zeros(1,nsamp);

qout = zeros(1,nsamp);

r = zeros(1,nsamp);

theta = zeros(1,nsamp);

for i=1:NN

atts = 10.^(-0.05.*attn(i)); % attenuation for current path

  

[itmp, qtmp] = delay(idata, qdata, nsamp, delay_samp(i));

[r_single, iout_single, qout_single] = fade2(itmp, qtmp, nsamp, tstp, fm, N1_arr(i), counter_arr(i), flat);

  

counter_arr = counter_arr+200; % update counter

  

iout = iout + atts.*iout_single./sqrt(total_attn);

qout = qout + atts.*qout_single./sqrt(total_attn);

  

end

r = sqrt(iout.^2+qout.^2);

Answer 1

I give the explaination in Bold and Italic:

this code genrate gfunction named Jake

the input to the functions are

% idata input Ich data

% qdata input Qch data

% nsamp Number of samples to be simulated

% fs Sampling frequency (Hz)

% fc Carrier Frequency (Hz)

% NN Number of paths

% N1 Number of waves in order to generate fading

% velocity Mobile speed in Km/h

% counter Fading counter

% delay_time Delay for each fading path (ns)

% attn Attenuation level for different fading paths (dB)

% flat flat fading or not

% r Envelope of fading channel complex impulse response

The output of the Functions

% iout output Ich data

% qout output Qch data

function [r, iout, qout] = Jake(idata, qdata, nsamp, fs, fc, NN, N1_arr, velocity, counter_arr, delay_time, attn, flat)

The following steps are used to explain about variables are used inside the function.. it will not execute while run the code

%****************************** variables *******************************

% idata input Ich data

% qdata input Qch data

% nsamp Number of samples to be simulated

% fs Sampling frequency (Hz)

% fc Carrier Frequency (Hz)

% NN Number of paths

% N1 Number of waves in order to generate fading

% velocity Mobile speed in Km/h

% counter Fading counter

% delay_time Delay for each fading path (ns)

% attn Attenuation level for different fading paths (dB)

% flat flat fading or not

% r Envelope of fading channel complex impulse response

% iout output Ich data

% qout output Qch data

%************************************************************************

v = velocity./3.6; % m/s

c = 3e8;%its light speed 3*10^8

fm = fc*v/c; % Maximum doppler frequency (Hz)

delay_samp = round(delay_time.*fs.*1e-9); % normalized delay time in number of samples

total_attn = sum(10.^(-1.0.*attn./10.0)); % normalize the power

tstp = 1/fs; % minimum time resolution

iout = zeros(1,nsamp);%initalize the iout value

qout = zeros(1,nsamp);%initalize the qout value

r = zeros(1,nsamp);%initalize the r value to zero

theta = zeros(1,nsamp);%initalize the theta value to zero

%Create loop to calculate iout and rout value for all samples which is taken

for i=1:NN

atts = 10.^(-0.05.*attn(i)); % attenuation for current path

  

[itmp, qtmp] = delay(idata, qdata, nsamp, delay_samp(i));

[r_single, iout_single, qout_single] = fade2(itmp, qtmp, nsamp, tstp, fm, N1_arr(i), counter_arr(i), flat);

  

counter_arr = counter_arr+200; % update counter

  

iout = iout + atts.*iout_single./sqrt(total_attn);

qout = qout + atts.*qout_single./sqrt(total_attn);

  

end

r = sqrt(iout.^2+qout.^2);%its formula to find Envelope of fading channel complex impulse response