Problem with for loop in given algorithm

Hello all, I am trying to code the following statement using for loop but not getting it clearly.

Queue length at a node in time slot 't+1' = Queue length at a node in time slot 't' + number of packets arrival in time slot 't'.

This is what I had tried:

T = 100; % Total slots
nodes = 8 % Total nodes
ini_q_len = 10; % Queue length at node 1 in time slot 't'

n = 10; % number of packets
p = 0.2; % probability of successful arrival of packets
for t = 1:T % each time slot  
    %% Queue length of each nodes
    for i = 1:nodes
        X(i) = ini_q_len+ binornd(n,p);
    end
end

The problem with this is that I am not getting how to bring in for loop Queue length at a node in time slot 't' i.e., how to include previous slot queue length.

Any help in this regard will be highly appreciated.

Answer 1

[VBBV]

unless Queue length value is not varying, you can initialize it as below and access in 2D matrix to include previous queue length values

T = 100; % Total slots
nodes = 8 % Total nodes
ini_q_len = repmat(10,1,100); % Queue length at node 1 in time slot 't'
K = 4; % some constant
for t = 1:T % each time slot  
    %% Queue length of each nodes
    for i = 1:nodes
        X(i,t) = ini_q_len(t)+ K;
    end    
end

[charu shree]

Thank you sir for your answer. I had edited my question Could pls check it once again....

[charu shree]

@VBBV sir in your case also every time ini_q_len = 10 is coming in for loop....Its not what I am expecting ...

[VBBV]

May be like this

T = 100; % Total slots
nodes = 8 % Total nodes
ini_q_len = zeros(1,100); % Queue length at node 1 in time slot 't'

% assume 10 initially
ini_q_len(1) = 10;

K = 4; % some constant
for t = 1:T-1 % each time slot  
    %% Queue length of each nodes
    for i = 1:nodes
        X(i,t) = ini_q_len(t)+ K;
    end  
    % generate values for ini_q_len using an expression (shown below is
    % e.g)
    ini_q_len(t+1) = ini_q_len(t)+num_packets(t); 
end

[charu shree]

Thank you sir...I had tried like this , could pls check whether its correct

clc;
clear all;
close all;

T = 100; % Total slots
nodes = 8; % Total nodes
ini_q_len = repmat(10,T,nodes); % initial Queue length at every node  in time slot 't'
K = 4; % some constant
n = 10; % number of packets
p = 0.2; % probability of successful arrival of packets

for t = 1:T % each time slot
    t
    %% Queue length of each nodes
    
    for i = 1:nodes
        i
        b = binornd(n,p);
        X(t,i) = ini_q_len(t,i)+ b;  
    end
    
    
end

[VBBV]

Queue length at a node in time slot 't+1' = Queue length at a node in time slot 't' + number of packets arrival in time slot 't'.

This is not whats happening in your code. Check code i have shown how its done

[charu shree]

@VBBV sir in your code, num_packets(t) is not declared earlier...from where its coming ?

[VBBV]

It's an e.g. to include packets in your algorithm. You can replace it with suitable variable. E g. Variable n in your case which is assigned 10 earlier.

If the number of packets for each time slot is same , then you can modify the line in outer loop as

ini_q_len(t+1) = ini_q_len(t)+n; 

otherwise

% where n is a vector containing number of packets for each time slot 
ini_q_len(t+1) = ini_q_len(t) + n(t); 

[charu shree]

@VBBV sir, Still not coming properly ....

[VBBV]

what is error you get ? can you explain Still not coming properly .... ? you need to use this code

T = 100; % Total slots
nodes = 8 % Total nodes
ini_q_len = zeros(1,100); % Queue length at node 1 in time slot 't'
n = 10;
% assume 10 initially
ini_q_len(1) = 10;

K = 4; % some constant
for t = 1:T-1 % each time slot  
    %% Queue length of each nodes
    for i = 1:nodes
        X(i,t) = ini_q_len(t)+ K;
    end  
    % generate values for ini_q_len using an expression (shown below is
    % e.g)
    ini_q_len(t+1) = ini_q_len(t)+n(t);  % n if no of packets are same each slot
end

[charu shree]

@VBBV Ok sir...I tried it like this ...could u pls check it

clc;
clear all;
close all;
T = 100; % Total slots
nodes = 8; % Total nodes
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 in time slot 1

for t = 1:T-1 % each time slot  
    for i = 1:nodes
        q_len(i,t+1) = q_len(i,t)+pack_arr(i,t);   
        %x = q_len(t)+pack_arr(i,t);    
    end 
end

[VBBV]

Ok, it looks fine now. So, this algorithm only determines queue length at time slot t based on the number of packets arrival at time slot t,

[charu shree]

Yes sir....Thanks a lot for your cooperation...really learning a lot from peoples like you...

[VBBV]

Ok, np, if you think my answer helped solved your problem, please accept it