ble_csma_test.m

MATSNL is a package of MATLAB M-files for computing wireless sensor node lifetime/power budget and s

clear;
% Unit time for random backoff
unit_backoff=1*(10^-3); % (1) msec
% Probability of Idle channel upon clear channel accessement
ch_idle_prob=0.5;
ch_busy_prob=1-ch_idle_prob;
avg_sample=100000;
for h=1:15
    % Maximum number of random backoff for channel busy
     max_backoff_num=h;

    P(h)=max_backoff_num;

    for u=1:avg_sample

        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        %Compute thoretical listening time
        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%        
        if ch_idle_prob~=0.5
        A=2*(1-(2*ch_busy_prob)^max_backoff_num)...
            *(1-ch_busy_prob)/(1-2*ch_busy_prob)-(1-(ch_busy_prob)^max_backoff_num);
        B=(ch_busy_prob^max_backoff_num)*(2^max_backoff_num-1);
        % Theoretical avg_listen_delay
        avg_listen_delay=unit_backoff*(A+B);
        else
            avg_listen_delay=unit_backoff*((max_backoff_num-1)+(0.5^(max_backoff_num))*(max_backoff_num+1) );
            
        end

        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        % Simulation
        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        % Simulation avg_listen_delay
        avg_listen_delay_simul=0;
        % Length of backoff for each trial
        len_backoff=0;
        backoff_listen_energy=0;
        Is_channel_IDLE=0;
        m=1;
        i=1;
        while (Is_channel_IDLE==0)
            % Binary Exponentail Backoff
             len_backoff=unit_backoff*uniform_gen(0,2^m);

            len_backoff_log(i)=len_backoff;
            i=i+1;
            % Update
            avg_listen_delay_simul=avg_listen_delay_simul+len_backoff;
            % Channel access (Busy or Idle)
            Is_channel_IDLE=bern_gen(ch_idle_prob);

            m=m+1;
            % If number of backoff exceed the maximum number of backoff,
            % then stop and report channel failure
            if(m> max_backoff_num)
                break;
            end
        end

        avg_listen_delay_simul_log(u)=avg_listen_delay_simul;
    end
    disp(['simul: ',num2str(mean(avg_listen_delay_simul_log))]);
    disp(['thy: ',num2str(avg_listen_delay)]);

    mean_num_thy(h)=avg_listen_delay;
    mean_num_sim(h)=mean(avg_listen_delay_simul_log);
    mean_num_std(h)=std(avg_listen_delay_simul_log);
    U(h)=max(avg_listen_delay_simul_log);
    L(h)=min(avg_listen_delay_simul_log);
end

h2=plot( (P),mean_num_sim,'b',(P),mean_num_thy,'.-r');
set(gca,'FontSize',18);
xlabel('The maximum number of backoff, P');
ylabel('Average listening delay, L(sec)');


% h1=errorbar((P),mean_num_sim, L,U,'+');
%  hold on;
%  h2=plot( (P),mean_num_sim);
% set(gca,'FontSize',18);
% xlabel('The maximum number of backoff, P');
% ylabel('Average listening delay, L(sec)');