Calculating throughput for users for 10000 times

Hi,i want to find the throughput of N users which are from 1 to 20,I defined it in a vector beacuse i want to run 10000 times for single user up to 20 and used another loop within the loop,after calculating the Throughput i am adding it in count and saving in variable count beacuse of 10000values,the value of count is divided by no of simulations i have run and save in S for user 1 to 2 and in the end ploting it ,but i am getting a straight decreasing graph,can any body help me to find the mistake i am doing???

clear all
close all
clc
simulations=10000;
n_vec=1:2:20;
R=[];
for n=n_vec
 count=0;
 S=0;
for sim=1:simulations
B=0.3;
phi=(1-B)./n; 
tau=B./n;
Bbn=20*1000;
Rbn = phi*Bbn;
BR=n.*Rbn;
PRn=0.0002224 ;
Ehn=(1-B-phi)*PRn;
 Ptr=Ehn/tau;
Kn=0.6;
Bandwidth=100*1000;
Psi=Kn*Bandwidth;
No=-174;
hn=rand;
po=No/hn;
gema=1/po;
Rhn=tau*Psi*log2(1+gema*Ehn/tau);
TR=n.*Rhn;
RTotal=BR+TR;
count=count+RTotal;
    end
S=count./simulations;
    R=[R S];
end
plot(n_vec,R)
    

Answer 1

[Jan]

I cannot follow your explanations. I start with cleaning your code:

simulations = 10000;
n_vec = 1:2:20;
R = zeros(1, simulations);  % Pre-allocate

% Move constants out of the loop:
B   = 0.3;
PRn = 0.0002224 ;
Bbn = 20*1000;
Kn  = 0.6;
Bandwidth = 100*1000;
Psi = Kn*Bandwidth;
No  = -174;

for in = 1:numel(n_vec)
  n = n_vec(in);

  phi = (1 - B) ./ n; 
  tau = B ./ n;
  Rbn = phi * Bbn;
  BR  = n .* Rbn;
  Ehn = (1 - B - phi) * PRn;
  Ptr = Ehn/tau;
  
  count = 0;
  for sim = 1:simulations
    TR     = n .* tau * Psi * log2(1 + rand * Ehn / tau / No);
    RTotal = BR + TR;
    count  = count + RTotal;
  end
  S     = count ./ simulations;
  R(in) = S;
end
plot(n_vec, R)

Yes, this looks almost like a straight line, but is is none:

diff(R)

You see, the differences are from -0.076 to -0.085. This is exactly what the given code instructs Matlab to calculate. The effects of the rand value are damped massively, by dividing it by a large value and adding 1 - and by takeing the log2 afterwards:

TR = n .* tau * Psi * log2(1 + rand * Ehn / tau / No) 
   = n .* tau * Psi * log2(1 + rand * ([-5.9e-6 to -5.9e-5]))

So if the value of rand is 0 or 1 changes the value of TR marginally only.

There is no chance to guess, why you expect another result or why you assume, that there is a mistake.

[Maheen Fazal]

Thank you sir for your precious time

[K Venkatesh]

how to Calculating throughput for muti-hop routing in wireless network.

Ex. source (s) to destination (d)

path is: s -r2-r4-d (r2 and r4 Relay nodes)

plz help me

[Jan]

@K Venkatesh: Please do no hijack another thread by injecting a new question in the comments and as an answer. Open a new thread by asking your own question. Mention more details there, because the current explanations are too lean to be answered.