varargout=link_sim_conv(varargin)

function varargout=link_sim_conv(varargin)
%LINK_SIM_CONV Simulate blocking in circuit switched tandem network.
%   [BLOCKING]=LINK_SIM_CONV(C,L,LOAD,NB_GEN) simulates blocking in tandem
%   network, where C is the number of channels, L is the number of links
%   between source and destination, LOAD is the load in Erlangs generated on every
%   link and NB_GEN is the number of simulation iterations [1].
%
%   BLOCKING is the vector of simulated results, where BLOCKING(i) is the
%   value of simulated blocking propability between first node and i node.
%
%   The bigger the NB_GEN the more accurate results will be. A good number
%   is i.e. 10000.
%
%   See also LINK_SIM_NO_CONV.
%
%   References:
%       [1] Milan Kovacevi, Anthony Acampora, "Benefits of Wavelength
%       translation in All-Optical Clear Channel Networks", IEEE Journal on
%       Selected Areas in Communications, vol. 14, June 1996 

%   Copyright 2003-2004 Przemyslaw Pawelczak
%   E-mail: [e-mail]
%   Wroclaw University of Technology, Poland
%   $Revision: 1.0 $  $Date: 2004/03/23 00:00:00 $

%Exeption handling
message=nargchk(4,4,nargin);
testing_int=[varargin{1},varargin{2},varargin{3},varargin{4}];
if ~isempty(message)
    error('MATLAB:CREATE_RAND_NETWORK:NumberOfInputArguments',...
        message);
end
if find(isnan(testing_int))
    error('MATLAB:CREATE_RAND_NETWORK:ArgumentType',...
        'Arguments must be numbers');
end
%Check if VARARGIN are positive integers
if sum([testing_int(1:2)<0,fix(testing_int(1:2))~=testing_int(1:2)])~=0
    error('MATLAB:CREATE_RAND_NETWORK:ArgumentType',...
        'Arguments must be positive integers');
end

C=varargin{1}; %Number of channels
L=varargin{2}; %Number of links
load=varargin{3}; %Total load [Erl]
number_generations=varargin{4}; %Number of generations for holding times

for link=1:L
    %Memory reservation
    number_blocked_temp=0;
    number_blocked=0;
    number_connections(1:link)=0;
    %Reserve memory for vector of connections for every link
    for t=1:link
        connections_vector{t}=[];
    end
    
    %Number of times to perform simulation
    for g=1:number_generations
        for t=1:link
            untill_next(t)=-log(1-rand)/load; %Exponential distribution of time untill next call arrives
            %(Poisson arrival)
            holding_time(t)=-log(1-rand); %Exponential distribution of holding time
            
            %Check blocking
            if length(connections_vector{t})==C
                %If all channels are busy then there is blocking
                number_blocked_temp=number_blocked_temp+1;
            else
                %Else - assign new channel to new connection
                connections_vector{t}=[connections_vector{t},holding_time(t)];
            end
            
            %Decrement all holding times
            for w=1:length(connections_vector{t})
                if connections_vector{t}(w)-untill_next(t)>0
                    connections_vector{t}(w)=connections_vector{t}(w)-untill_next(t);
                else
                    connections_vector{t}(w)=0;
                end
            end
            %Remove all zero elements - free channels
            connections_vector{t}=nonzeros(connections_vector{t})';
        end
        
        %Update number of blocked calls - NUMBER_BLOCKED_TEMP needed for
        %every iteration with more links
        if number_blocked_temp~=0
            number_blocked=number_blocked+1;
        end
        %Clear NUMBER_BLOCKED_TEMP
        number_blocked_temp=0;
    end
    
    %Percentage of blocking for every node
    blocked(link)=number_blocked/number_generations*100;
end

varargout{1}=blocked;