Question

In my program , suppose I fix no. of users N=6 .
Threshold value of SIR SIRo=6; Output generated is SIRmean=10 (suppose).

I want to make a loop so that

if SIRmean < SIRo

   disp N=6

else

  decrease the counter till SIRmean> SIRo
   and display the value of N for which this condition holds true.

end

Answer 1

You can use simple for loop with downcounter and break on condition:

N=6;
for k=N:-1:0
   SIRmean = calc_SIR_mean(N);
   if SIRmean < SIRo
      disp(['N=' k])
      break;
   end
end

Function calc_SIR_mean should return mean value based on number of users (it is not clear from your question how you receive this value).