Ensuring each node becoming as CH exactly one time in LEACH

I am implementing my LEACH protocol. I want each of 100 nodes become as a CH exactly one time or in one round among 100 rounds. Below is the code snippet for CH making. In this code nodes become multiple time as CH, but i want exactly once. How to make it. Selecting one node uniquely based on probability in each round seems tricky.

close all;
clear all;
clc;
num_nodes = 100;       
rounds = 100;          
probability_threshold = 0.1;

% Initialize cluster heads
cluster_heads = zeros(rounds, num_nodes);

for r = 1:rounds
    % Select cluster heads probabilistically 
    for i = 1:num_nodes
        if rand <= probability_threshold %need to make exactly one node satisfy the condition 
            cluster_heads(r, i) = 1;  % Node becomes a cluster head
        end
    end
end

Pls clarify!

Answer 1

[Paras Gupta]

Hey,

I understand that you want to ensure each node is selected exactly once as a Cluster Head (CH) while using a probability threshold. We can achieve this by maintaining a list of nodes that have already been selected and ensuring they are not selected again in subsequent rounds.

Here's an updated version of your code to accomplish this:

close all;
clear all;
clc;
num_nodes = 100;       
rounds = 100;          
probability_threshold = 0.1;

% Initialize cluster heads
cluster_heads = zeros(rounds, num_nodes);
selected_nodes = false(1, num_nodes);  % Track selected nodes

for r = 1:rounds
    while true
        % Select a node probabilistically
        for i = 1:num_nodes
            if ~selected_nodes(i) && rand <= probability_threshold
                cluster_heads(r, i) = 1;  % Node becomes a cluster head
                selected_nodes(i) = true; % Mark node as selected
                break;
            end
        end
        % Check if a node was selected in this round
        if any(cluster_heads(r, :))
            break;
        end
    end
end

This approach ensures that each node is selected exactly once as a CH while still using a probability threshold.

Alternatively, we can use a deterministic approach by leveraging the 'randperm' function to generate a random permutation of nodes, ensuring each node is selected exactly once in 100 rounds. Here’s how you can do it:

close all;
clear all;
clc;
num_nodes = 100;       
rounds = 100;          

% Initialize cluster heads
cluster_heads = zeros(rounds, num_nodes);

% Create a permutation of nodes to ensure each node becomes CH exactly once
nodes_permutation = randperm(num_nodes);

for r = 1:rounds
    % Select the node that becomes a cluster head for this round
    selected_node = nodes_permutation(r);
    cluster_heads(r, selected_node) = 1;  % Node becomes a cluster head
end

You can refer to the following documentation for more information on the functions used in the code above:

• rand: https://www.mathworks.com/help/matlab/ref/rand.html
• randperm: https://www.mathworks.com/help/matlab/ref/randperm.html
• zeros: https://www.mathworks.com/help/matlab/ref/zeros.html

Hope this resolves your query.

[NALLARASU KRISH]

The idea of using randperm function is well thought.