Member Avatar for leelingling630

Hello:

I am writting a simulation code on Random Early Detection (RED) and when i run the simulation , the average delay is too high. Does anybody have some idea on it.I really can't get along with it now withouth any help . :cry: Please help me!!!!!!!!!!!!!

I have upload the coding of mine. The file name called sim12.cpp.

Hope will get reply soon... through my email - email removed by moderator

#include <iostream.h>
#include <stdlib.h>
#include <math.h>
#include <fstream.h>
#include <conio.h>

#define maxSource 10			//refer to maximum source that are 10 sources
#define maxEvent 2			//refer to number of events that are only 2, 0 for arrival, and 1 for departure
#define maxQSize 20	//maximum queue size is set to 20
#define serviceTime 0.122		//set the service time to 0.122
#define maxDelay 0.01		//set the maximum delay to 0.01

/*random early detection*/
#define wq 0.002
#define minth 5
#define maxth 15
#define maxp 0.02
#define MAX_BANDWIDTH 512000
#define avg_pktsize 500

double ev_time[maxSource][maxEvent];						//the main event time
double smallestEvent;									//holds the smallest eventime. Used by scheduler() and Clock()
double simClock;
double last_check;
double iat;
double totalDelay;
int load=0;
double arrivalTimeQ[maxQSize+1];						//holds the arrival time of customers that enter the queue (maxSource+1 because the index of 0 is not used)
int eventType;											//holds the event type, it is either 0 or 1. Used by scheduler() and selectEvent()
int packetNum;											//holds the customer number to be entered to the system. Use by the scheduler() and the arrival() or departure()
int serviceCounter = 0;									//if the service counter is idle, then 0
int packetNumQ[maxQSize+1];								//holds the customer number that enters into the queue (maxSource+1 because the index of 0 is not used)
int currentQSize=0;										//holds the current queue size. Used by the arrival() and departure()
double numPacketArrived;										//holds the number of customers arrived in the system
double  numPacketDeparted;									//holds the number of customers completed an entire cycle in the bank
double totalCustLost;										//holds the number of customers lost when the Q is full

void calculateavg1();
void calculateavg2();
//double calculateavg1(double avg);
//double calculateavg2(double avg);

/*random early detection*/
double avg=0;
int m;
double idletime_;
double pa;
double pb;
int count=0;
double ptc=0;



ofstream fout("output.txt", ios::app);

void IAT()
{
	double rand_size = 0.5 * pow(2.0,8.0 * sizeof(int));

	double x;
	while(1)
	{
		x = (float) rand();
		if (x!=0.0)
			break;
	}

	iat = - (log (x/rand_size))/load;

}

//initialize the values of variables
void init()
{
	totalDelay = 0.0;
	simClock = 0.0;
	numPacketArrived = 0;
	numPacketDeparted = 0;
	totalCustLost = 0;
	currentQSize = 0;
	
	load += 10;
	IAT();
	serviceCounter = 0;
	
	 
}

//generate events and create the starting arrival time of the simiulation
void eventList()
{
	for (int i=0; i<maxSource; i++)
	{
		for (int j=0; j<maxEvent; j++)
		{
			ev_time[i][j] =0.0;		//this is to return a value between 0.00 till 9.99
			if (j==1)									//j==1 means the departure time slot coz 0 is for arrival
				ev_time[i][j] = 1.0e+30;				//departure time set to infinity
			//fout<< ev_time[i][j] << "\t";
		}
		// fout<< endl;
	}
}


//find the smallest event time to be placed into the system
void scheduler()
{
		//	fout<< "Scheduler" << "\t";


	smallestEvent = 1.0e+30;



	for (int i=0; i<maxSource; i++)
	{
		for(int j=0; j<maxEvent; j++)
		{
			if(ev_time[i][j] < smallestEvent)
			{
				smallestEvent = ev_time[i][j];			//records the smallest time in the sources
				eventType = j;							//records the event type, either 0 or 1
				packetNum = i;							//records the customer number
			}
		}
	}
}

//assign the smallest event time to a clock


void Clock()
{
	simClock = smallestEvent;							//the clock ticks for the updates
	//fout<< simClock << "\t" ;
}





//moves the customers in Q to the front of the Q
void swap()
{
	for (int i=1; i<maxQSize; i++)
	{
		arrivalTimeQ[i] = arrivalTimeQ[i+1];
		packetNumQ[i] = packetNumQ[i+1];
	}
}


void idle()
{
	if(currentQSize!=0)
	{
		idletime_=simClock;
	}
	else 
	{
		idletime_=0.0;
	}
}

void avg1()
{
	
	if(avg<minth)
	{
		count=-1;
		++numPacketArrived;
		currentQSize++;
		
		
		
	}
	else if (avg>=minth&&avg<maxth)
	{
		count=count+1;
		
		//calculate pa

		pb=maxp*(avg-minth)/(maxth-minth);
		pa=pb/((1-count)*pb);
		

		if(pa<maxp)
		{
		
			++numPacketArrived;
			currentQSize++;
			
		}
		else
		{			
			totalCustLost++;
			currentQSize--;		
		}
	}

}

void calculateavg1()
{
	
		avg=((1-wq)*avg)+(wq*currentQSize);
		fout<<"avg"<<avg<<endl;
		avg1();	
	
}

void calculateavg2()
{
	ptc=MAX_BANDWIDTH/(8.0*avg_pktsize);

	m=int(ptc*(simClock-idletime_));
	idle();
	//m=int(idletime_/(avg_pktsize/MAX_BANDWIDTH));
	avg=pow(1-wq,m)*avg;
	avg1();
	
	
		
}




//arrival function
void arrival()
{
	++numPacketArrived;

	IAT();


	ev_time[packetNum][0] = simClock + iat;				//schedule the next customer

	if (serviceCounter == 0)							//service counter idle
	{
		serviceCounter = 1;								//make the service counter busy
		ev_time[packetNum][1] = simClock + serviceTime;	//schedule the departure time
	}
	else if (serviceCounter == 1)						//service counter busy
	{
		if (currentQSize < maxQSize)
		{
			calculateavg1();
		
			currentQSize++;								//increase the Q size
			//the queue starts at index of 1, not 0
			arrivalTimeQ[currentQSize] = simClock;			//records the arrival time of customer into the Q
			packetNumQ[currentQSize] = packetNum;				//records the customer number in the Q
			
		}
		
		else if (currentQSize==0)
		{
			
				calculateavg2();
		
		}

		else 
		{
			++totalCustLost;
			
				 //	fout<< "Customer " << packetNum << " is lost!!" << endl;
		}
		


	}
}


//departure function
void departure()
{
	double delay;									//holds the delay of the customer temporarily
	int cid;										//holds the customer number from the Q temporarily

	++numPacketDeparted;								//increments the total number of customers departed after being served


	if (currentQSize == 0)							//the Q is empty
	{
		serviceCounter = 0;							//make the service counter free
		ev_time[packetNum][1] = 1.0e+30;				//change the departure time to infinity as the customer has left
	}
	else if (currentQSize > 0)
	{
		--currentQSize;								//reduce the Q size as the customer moved out of the Q
		ev_time[packetNum][1] = 1.0e+30;				//change the departure time to infinity as the customer has left

		delay = simClock - arrivalTimeQ[1];			//calculate the delay for that 1st customer in the Q
		totalDelay += delay;						//calculate the total delay of the system

		cid = packetNumQ[1];							//extract the 1st customer number from the Q
		ev_time[cid][1] = simClock + serviceTime;	//schedule the departure time for the customer from the Q

		swap();
											//moves the customers to the front of the Q
	}
}


void selectEvent()
{
	switch (eventType)
	{

	case 0	:      //	fout<< "Arrival" << endl;
				arrival();
				break;
	case 1	:      //	fout<< "Depart" << endl;
				departure();
				break;
	}
}


void result()
{
	cout<< "TotalDelay \t\t" << totalDelay << endl;
	cout<< "SimClock \t\t" << simClock << endl;
	cout<< "TotalCustLost \t\t" << totalCustLost << endl;
	cout<< "numPacketArrived \t" << numPacketArrived << endl;
	cout<< "numPacketDeparted \t" << numPacketDeparted << endl;
	cout<< "CurrentQSize \t\t" << currentQSize << endl;					//display currently how many person in Q
	cout<< "ServiceCounter \t\t" << serviceCounter << endl << endl << endl;
	cout<< "Customer Loss Ratio : " << (double) totalCustLost / numPacketArrived << endl;
	cout<< "Average Delay : " << (double) totalDelay / numPacketDeparted << endl;
	cout<< "pa:"<<pa<<endl;
	fout<< load << "  " << totalDelay/numPacketDeparted <<" "<<totalCustLost/numPacketArrived <<endl;
	//cout<<"count"<<"   "<<count<<endl;
	cout<<"avg"<< "  "<<avg<<endl;
	
	//cout<<"avg "<<avg<<endl;
	//fout<<"pa  "<<pa<<endl;


}

//function that clears the arrival events by setting them to infinity
/*void clearArrival()
{
	for (int i=0; i<maxSource; i++)
	{
		for (int j=0; j<maxEvent; j++)
		{
			if (j==0)							//j==0 means the arrival
			ev_time[i][j] = 1.0e+30;			//arrival time is infinity
		}
	}
}
*/


void main()
{



//       clrscr();

	load = 0;


	for (int i=0; i<10; i++)
	{
		init();
		eventList();


	while (numPacketDeparted <= 5000)
	{
			//once the system achieved this target num of customer, it will clear the arrival event
												//and continue clearing the bank, meanning only departure
		scheduler();
		Clock();
		selectEvent();
	}



	result();

	}//e-for


} //e=main
  • 4 Contributors
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  • 3 Years Discussion Span
  • Latest Post Latest Post by ArkM
Member Avatar for taptanh

hi!
i also do that. you can send it to me, ok? modified simulation code or code!
thank!
<email snipped>

commented: Don't rez old topics. Leave them dead and buried! #_# +0
Member Avatar for ArkM

You have a rather strange code to generate exponential distribution. Use RAND_MAX macros from <stdlib.h> (it's not equal to the funny pow expression).

const double max_rand = RAND_MAX;
...
...   log (x/max_rand) ...

With 32-bit compilers you have huge intervals because of (usually) RAND_MAX is equal 32767 only (rand() is a very bad pseudorandom numbers generator ;))...

Alas, I have no time to inspect your code more carefully now.

Member Avatar for Salem

> Alas, I have no time to inspect your code more carefully now.
Take your time, it was posted (and abandoned) on 8th Jan 2005

Member Avatar for ArkM

What's a nightmare!..
Thank you, Salem ;)

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