Matlab code to find network capacity throws error

I am trying to calculate network/users' capacity through the code below but I constantly get "Subscript indices must either be real positive integers or logicals". I have almost spent a decade finding solution to it without success. The error is at the Throughput_(j) part.

%%%Parameters
    B = 20*10^6;
    No = 0.1e-15;
    N = No*B;
    Pstatic = 50; %%Fixed power in the circuit in Watt 
    fc = 2*10^9;  %% carrier frequency
    ht = 30; %%Transmitter height
    hr = 2;  %%Receiver height
    AP = 2; %%Number of nodes
    UE = 4; %%Number of users

      %%Calculating location between nodes and UEs

      UserLocationX = randi(4, 1, 4);
      UserLocationY = randi(4, 1, 4);
      AccessPointX = randi(4, 1, 2);
      AccessPointY = randi(4, 1, 2);

      for p = 1:1:500;  %%power allocation to users
        for i = 1:AP;
          for j = 1:UE;

       compute_distance = pdist2([AccessPointX(:) AccessPointY(:)],[UserLocationX(:) UserLocationY(:)]);

      %%%Calculating the pathloss

      C_Rx = 3.2*(log10(11.75*hrx))^2 - 4.97;

      pathloss_compute = 69.55+26.16*log10(fc)-13.82*log10(ht)-C_Rx+(44.9-6.55*log10(ht))*log10(compute_distance);

%%Calculating the capacity.....Error throws up here!!!  "Subscript indices must either be real positive integers or logicals".

      Throughput_(j) = B*log2(1 + p(j)*pathloss_compute/(p(j-1)*pathloss_compute + N));
              end
           end
      end

Answer 1

[Image Analyst]

Since you didn't supply hrx, we can't run your code to reproduce the error.

You can look at the FAQ: https://matlab.wikia.com/wiki/FAQ#How_do_I_fix_the_error_.22Subscript_indices_must_either_be_real_positive_integers_or_logicals..22.3F

In the line

Throughput_(j) = B*log2(1 + p(j)*pathloss_compute/(p(j-1)*pathloss_compute + N));

you have j-1. Well, the first j is 1, so j-1 is zero. There is no zeroeth element of an array. I suggest you rethink what your algorithm is trying to do.

[Oladele Felix]

@Image Analyst, Sorry. The hrx is mistaken for hr, the receiver height which is 2. As I said, I want the algorithm to calculate the throughput of the network. That j-1 part seeks to calculate the interference from other users except user j. I'm not even sure if I correctly calculated the distance and pathloss between nodes and users either. Thanks

[Oladele Felix]

In my opinion, if I want to find the throughput for two users, i.e UE = 2, the first user would be: Throughput_(1) = B.*log2(1 + p1.*pathloss_compute1./p1.*pathloss_compute1 + N)); while the second user would be: Throughput_(2) = B.*log2(1 + p2.*pathloss_compute2./(p1.*pathloss_compute2 + N));. So if I want to compute for i-th user, it should be: Throughput_(i) = B.*log2(1 + p(i).*pathloss_compute(i)./(p(i).*pathloss_compute(i-1)+ N)); according to Shannon capacity formular, T(i) = log2(1 + P(i)*G(i)/(∑_(j=1)^(i-1)Pj.*Gi +N)); where the term in sigma is the interference from other users.