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Concurrent Programming with Java
Lab Manual, Version 1.0, F. Astha Ekadiyanto, 2002.

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Lab 1: Introduction to Lab. Environment and Object Orientation

Object First
- Cell Class
- RBS Class (Radio Base Station)
- MSC Class (Mobile Switching Center)

Msc Class

Mobile Switching Centre is the central of the mobile network. It registers all the RBS and their corresponding coverage. All management issues in the mobile network are served by MSC. This means MSC responsible for all services to mobile stations and allocate the best Rbs to serve a certain location. The Msc should be able to access any Rbs objects in its record and also the Cell objects in the corresponding Rbs. This communication will ensure the capability of an Msc to provide services.

In this Lab, a simplified Msc is defined as follows:

What an MSC should have?

Of course an array of RBS objects to store all the registered Rbs references.
Capacity of MSC in terms of number of RBS objects

What an MSC should behave?

Register all the RBSs into the array.
Finding RBS candidates to serve a certain point of access given by x,y coordinate.
Find RBS with a certain ID for administrative purposes since an Rbs considered to have a unique ID.
Show RBS information and its neighbors (to provide simple debugging on how the service provided. The output will be displayed in console).

These definitions can be implemented in Java Language as follows :

File name: Msc.java

Class Fields :

MAXRBS : a constant used to limit the Msc record capacity to a maximum number of Rbs.
numOfRbs : indicates the total number of Rbs registered in the Msc.
rbss : array of Rbs that stores all the Rbs records (references).

Class Constructors: There are no class constructor defined (but a primitive constructor will be implemented implicitly)

Class Methods:

addRbs(Rbs ) : registers the Rbs argument reference into the rbss array.
isRegistered(Rbs) : check whether an Rbs exists in the rbss array to prevent duplicates.
setNeighboring(Rbs,Rbs) : set two Rbs as neighbors (inform both Rbs that each other is neighboring)
findRbs(x,y) : Find an Rbs that can serve a certain point (x, y coordinate)
findRbs(String) : A polymorph of findRbs but with different function that is to find an Rbs in the rbss array that has the same ID as the String argument.
showNeighbors(Rbs) : Prints out all the Rbs' neighbors (access the Rbs' Enumeration list).

import java.util.Enumeration; //Required because Enumeration Class is used in the class
/**
 * Mobile Switching Center
 * @author CPwJ
 * @version 1.0 (2002)
 */
public class Msc
{
    private static final int MAXRBS=100; //Maximum RBS to be registered
    private int numOfRbs=0; //Number of RBS currently registered
    private Rbs[] rbss=new Rbs[MAXRBS]; //For storing RBS reference
    /**
    * Register an Rbs into Msc
    * @param Rbs the Radio Base Station to be registered
    */
    public void addRbs(Rbs station) 
    {
        if ( (numOfRbs < MAXRBS) && !(isRegistered(station)) ) 
             { rbss[numOfRbs++] = station; }
    }
    private boolean isRegistered(Rbs station) 
    {   
        for (int x=0; x<numOfRbs; x++) {
            if ( rbss[x]==station) return true;
        }
        return false;
    }
   /**
    * Set two Rbs as neighbors
    * @param Rbs1 First neighboring Radio Base Station 
    * @param Rbs2 Second neighboring Radio Base Station 
    */
    public static void setNeighboring(Rbs station1, Rbs station2) 
    {
        station1.addNeighbor(station2);
        station2.addNeighbor(station1);
    }
   /**
    * Find an Rbs that covers a point of access
    * @param x the point of access coordinate
    * @param y the point of access coordinate
    */
    public Rbs findRbs(double x, double y) 
    {
        for (int i=0; i<numOfRbs; i++) {
            if ( rbss[i].getCell().coverage(x,y)) return rbss[i];
        }
        return null;
    }
   /**
    * Find an Rbs with an Identification string
    * @param id the Identification String
    */
    public Rbs findRbs(String id) 
    {
        for (int i=0; i < numOfRbs; i++) {
            if ( id.equals(rbss[i].getID()) ) return rbss[i];
        }
        return null;
    }
   /**
    * List all the neighbors of an Rbs
    * @param Rbs the Rbs in the center
    */
    public static void showNeighbors(Rbs station) 
    {
        System.out.println("Neighboring RBS are:");
        station.resetElements();
        for ( Enumeration e = station; e.hasMoreElements();) 
            System.out.println(e.nextElement());
    }
}

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