traffic_sim.m

%Simulation of call traffic in a trunked communication network
%Mobile Communication Technology (Mr. Rajesh Sharma)
%Saurav Ratna Tuladhar <[e-mail]>, IOE/TU
%-----------------------------------------------------------------------
%10th July, 06 : Computation of Call arrival instances, Call termination
%time.
%Simulation completed on 9th August 2006 (needs confirmation!)
%Revision1: 28th August 2006 : Provision for monitoring channel usage for
%simulation interval
%------------------------------------------------------------------------
%Further enhancement needed: Channel usage calculation

clear all;
home;
C = 100;   %Number of calls made ( 100 taken for ease of comparision)
mIAT = input('Enter mean inter arrival time (mins):');
callInt =exprnd(mIAT,[C-1,1]); %Inter arrival time for 100 calls 


arrvInst = zeros(length(callInt)+1 ,1); % Call arrival instances
%Compute call arrival instances
arrvInst(1) = 0;  %First call arrives at time = 0
for k = 2:C,
    arrvInst(k) = arrvInst(k-1) + callInt(k-1);
end

mHT = input('Enter mean holding time (mins):');
holdTime = exprnd(mHT,[C,1]); %Holding time for 100 calls. 

termTime = zeros(C,1);  %Termination instances
%Compute call termination time
for k = 1:C,
    termTime(k) = arrvInst(k) + holdTime(k);    %Termination time = arrivalInstance + holdingTime
end


N = 10; %Number of trunked channels available
Serviced = 0;
Blocked = 0;
flagServed = 0;  %Flag is 1 if serviced
channels = zeros(N,1);  %Channel array
chUsage = N*ones(C,1);
%-----Determine : Serviced, Blocked calls-------------        
for i = 1:100,
     for k = 1:N,
         if( channels(k) < arrvInst(i))
             Serviced = Serviced + 1;
             flagServed = 1;    
             channels(k) = termTime(i);
             break;
         end
     end
     %Check remaining channels
     if(k < 5 )
         for j = k+1:5,
             if(channels(j) < arrvInst(i))
                 channels(j) = 0;      %If calls have been terminated clear the channels
              end
         end
     elseif (flagServed == 0)
         Blocked = Blocked + 1;
     end
     flagServed = 0;  %Reset Flag
%     channels = sort(channels);  %Sort channels according to termInst values
    for x = 1:N,
        if (channels(x) == 0)
            chUsage(i) = chUsage(i) - 1;
        end 
    end
end

display('Serviced calls :'); 
disp(Serviced);
display('Blocked calls :');
disp(Blocked);
stem(chUsage)
title('Channel Usage Graph');