How to implement the following task in MATLAB ?

Hello all, I am trying to code the following part in MATLAB. It is related to the queue length of a node which depenfds upon packet arrival and packet departure at the nodes and is mentioned as:

Queue length at a node in time slot 't+1' = Queue length at a node in time slot 't' + number of packet arrived in time slot 't' - number of packet departed in time slot 't'.

Note : Packet arrival follows binomial distribution and Packet departure is based on status of the link between the nodes (if status is 1 then packet is departed else not). The packet departed is calculated as: data rate * total time.

Following are my efforts:

sr = [1,2,2,2,3,3,3,4,5]; % various possible source
ta = [2,3,6,8,6,4,7,6,6]; % various possible targets
G = graph(sr,ta); % models the Graph
% Initial queue length
q_len = zeros(nodes,T); % Queue length 
% assume 10 initially
q_len(:,1) = 10;
n = 10; % number of packets
p = 0.2; % probability of successful arrival of packets
pack_arr = binornd(n,p,[nodes,T]); % number of packets arrival
nodes  = 8;
status = [1 2 2 1 2 2 2 1 1 ];
data_ rate = [0.399,	1.918 ,1.259, 	1.289, 2.228,	1.099, 1.736, 1.469, 0.131]; % Total Time
T = 100;
%% Queue length of each nodes
for t = 1:T-1
    for i = 1:nodes
        q_len(i,t+1) = q_len(i,t)+pack_arr(i,t);   
    end 
end 

My query is that, I am unable to code for packet departed part in above for loop. Any help in this regard will be highly appreciated.

[Torsten]

Don't you think it would be better first to read a book on queuing theory before starting to simulate such processes in MATLAB ?

[charu shree]

Thank u sir for ur response...But I think I had written correct code ...

Answer 1

[Shubham Dhanda]

Hi,

I understand that you want to find the number of packets departed at the nodes. Packets departed depend on status value and is given by data rate* total time

Below is the MATLAB code implementation of the problem:

sr = [1,2,2,2,3,3,3,4,5]; % various possible source
ta = [2,3,6,8,6,4,7,6,6]; % various possible targets
G = graph(sr,ta); % models the Graph
nodes = 8;
status = [1 2 2 1 2 2 2 1 1 ];
data_rate = [0.399, 1.918 ,1.259, 1.289, 2.228, 1.099, 1.736, 1.469, 0.131]; % Total Time
T = 100;
% Initial queue length
q_len = zeros(nodes,T); % Queue length
% assume 10 initially
q_len(:,1) = 10;
n = 10; % number of packets
p = 0.2; % probability of successful arrival of packets
pack_arr = binornd(n,p,[nodes,T]); % number of packets arrival

 

 
%% Queue length of each nodes
for t = 1:T-1
    for i = 1:nodes
        % Calculate number of packets departed
        if status(i) == 1 % link is available
            pack_dep = round(data_rate(i)*T); % round to nearest integer
        else
            pack_dep = 0; % no packets depart
        end
        % Update queue length
        q_len(i,t+1) = q_len(i,t) + pack_arr(i,t) - pack_dep;
    end
end

Hope this helps.