基于蒙特卡罗模拟ALOHA附Matlab代码.zip

N=60; Ts=0.0002; %Ts= 1200/6000000= 0.2msec lamda= 250:200:2050; %[packet/sec] lamda2= lamda.*Ts; % lamda2=arrival rate=0.05:0.03:0.32 [packet/slot] s = zeros(1, length(lamda)); g = zeros(1, length(lamda)); d = zeros(1, length(lamda)); for l=1:1:length(lamda) %TIMING PARAMETERS (PART 1) num_arrival_per_station = 1000000; interarrival_time= exprnd(1/(lamda2(l)), N, num_arrival_per_station); %[slot] arrival_schedule= cumsum(interarrival_time,2); %cumsum:Cumulative sumcollapse. B = cumsum(A,dim) %this double loop method works but very inefficient % arrival_schedule= zeros(N,num_arrival_per_station); % for n =1:N % for i = 1:num_arrival_per_station % arrival_schedule(n, i) = sum(interarrival_time(n, 1:i)); % end % end retransmission_schedule= zeros(1,N); simulation_time=1000000; current_time_slot=1; %DIFFERENT TRANSMIT INDICATORS (PART 2) transmit_status_indicator = zeros(1,N) ; % 0 for not transmitting, 1 for transmitting retransmit_status = zeros(1,N) ; % 0 for no retransmission, 1 for pending retransmission retransmission_attempt = zeros(1,N) ; %if pkt tx fail once becomes 1 , fail twice becomes 2, and so on ...useful for updating window for retransmission scheduling max_retransmission_attempt = 11; %%STATS PARAMETERS (PART 3) total_transmissions = 0; total_successful_transmissions = 0 ; %use for throughput computation total_delay_time = 0 ; %use for average delay computation packet_index=ones(1, N); while (current_time_slot < simulation_time) %%FUNCTION: check_whether_each_station_transmits_in_this_slot (PART 4) for j= 1:1:N %retransmission_schedule(1,j) if (retransmit_status(1,j)==1) %check if status is retransmit if (retransmission_schedule(1,j)==current_time_slot) %check if retransmission count down timer arrived transmit_status_indicator(1,j)=1; j_tx=j; end elseif (all(retransmit_status==0)==1) %no pendiong retranmission if (current_time_slot >= arrival_schedule(j,packet_index(1,j))) % there's a new packet transmit_status_indicator(1,j)=1; j_tx=j; end end end % Number of stations which transmit in this slot num_transmitting_stations = sum(transmit_status_indicator); total_transmissions = total_transmissions + num_transmitting_stations; %%FUNCTION: CHECK_SUCCESSFUL_OR_FAILED_TRANSMISSION (PART 5) if (num_transmitting_stations==1) %if transmission succeed total_successful_transmissions = total_successful_transmissions+1; % get packet arrival time. Based on difference between transmitted time and original arrival time, we can get this_unique_packet_delay_time this_unique_packet_delay_time_after_successful_tx= current_time_slot - arrival_schedule(j_tx, packet_index(1,j_tx)); total_delay_time = total_delay_time + this_unique_packet_delay_time_after_successful_tx; transmit_status_indicator(1,j_tx) = 0; %update tx status retransmit_status(1,j_tx) = 0; %update re-tx status %update which next packet to be served, do something with arrival_schedule? packet_index(1,j_tx)= packet_index(1,j_tx) + 1; %increase packet index at the station has packet successfully transmitted retransmission_attempt(1,j_tx)=0; retransmission_schedule(1,j_tx)=0; else %if transmission fails for j=1:1:N retransmit_status(1,j) = transmit_status_indicator(1,j); if ((retransmit_status(1,j)==1)&&(retransmission_schedule(1,j)<=current_time_slot)) %if (retransmit_status(1,j)==1) retransmission_schedule(1,j) = current_time_slot + randi([1, 2^(retransmission_attempt(1,j))+1],1); retransmission_attempt(1,j) = retransmission_attempt(1,j)+1; if (retransmission_attempt(1,j) > max_retransmission_attempt) %discard the packet and serving next packet packet_index(1,j)= packet_index(1,j) + 1; retransmission_attempt(1,j)=0; retransmission_schedule(1,j)=0; retransmit_status(1,j)=0; end transmit_status_indicator(1,j)=0; end end end current_time_slot = current_time_slot + 1 ; end %belongs to while loop of incrementing simulation time %Harvest STATISTICS 3 (PART 5) : process data that you obtain earlier s(1,l) = total_successful_transmissions/simulation_time; %normalized throughput rate [packet/slot] g(1,l) = total_transmissions/simulation_time; %normalized channel loading [packet/slot] d(1,l) = total_delay_time/total_successful_transmissions; %mean packet delay [slot/packet] %Use fprintf to directly display the text without creating a variable. However, to terminate the display properly, you must end the text with the newline (\n) metacharacter. fprintf(['\n Offered load (lamda2)[packet/slot]: %.3f packet/slot,', ... '\n Normalized throughput (s)[packet/slot]: %.3f packet/slot,', ... '\n Normalized channel loading (g)[packet/slot]: %.3f packet/slot,', ... '\n Mean packet delay (d)[slot/packet]: %.3f slot/packet \n'], lamda2(l), s(1,l), g(1,l), d(1,l)); end figure(1) plot(g,s) title('s vs g Performance Curve') xlabel('Normalized channel loading (g)[packet/slot]') ylabel('Normalized throughput (s)[packet/slot]') figure(2) plot(s,d) title('d vs s Performance Curve') xlabel('Normalized throughput (s)[packet/slot]') ylabel('Mean packet delay (d)[slot/packet]') figure(3) plot(lamda,d) title('d vs lamda Performance Curve') xlabel('Offered load (lamda)[packet/sec]') ylabel('Mean packet delay (d)[slot/packet]')