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ABSTRACT
In this paper we discuss how the location information provided by the GPS receiver can be used for efficient mobile usage. The network topology we are considering is comprised of fixed mobile base stations and mobile handsets. In the network the base stations and the mobile nodes are GPS equipped. The idea is to leverage the information of the fixed base stations and the mobile handsets positions, obtained via the GPS, to improve performance of the mobile routing to adaptively determine the appropriate destination mobile handset and to locate the nearby fixed base station using predefined set of algorithms. Our proposal supports the existing infrastructures in mobile communication with a slight modification by the inclusion of GPS receivers .

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SUBMITTED BY,
B.KARTHIKKAMAL &R.MANJUNATH, IIIECE,
GOVT. COLLEGE OF TECHNOLOGY, COIMBATORE-641013.

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INTRODUCTION
GPS(Global Positioning System) enables a device to determine their position (longitude, latitude and altitude) by getting information from the satellites. GPS satellites were first put into orbit in 1983 and from that time efforts have been underway to include GPS in everything from marine navigation to guided missiles to tracking golf balls. The GPS industry council has forecasted that the markets for the GPS applications will be at approximately $20 billion by the year 2010.
Wireless networks have also experienced explosive growth. Different types of wireless networks are emerging. Second generation cellular networks which provided only voice services are evolving into third generation systems which is also capable of providing data services. In this critical age, the efficient usage of mobile resources becomes essential.
In this paper we are going to investigate the application of the position information provided by GPS to wireless networks. Currently most work concerning mobile networking has been done without using any positioning schemes. As GPS receivers has become cheap and efficient, they can be embedded into the cellphones, base stations and other wireless access devices.
We consider the application of position information provided by GPS provided in cellular networks.In the following section we present the network section and the scenario we consider and our motivation on this subject.In the section next we discuss the application of position information provided by GPS to mobile routing.We present a routing scheme in which the mobile towers routes the call to the destination mobile with the help of the positioning information provided by the GPS system.We show that our scheme has significant advantages over the prevailing methods in which we donot use the positioning information.Finally we analyse the perfomance of this type of routing with respect to the current routing technique.Besides this we also analyse the merits and the future of this proposed concept.
MOTIVATION:
With the advent of mobile systems there is a rapid growth in this field. As a result the number of concerns providing these services is also increasing rapidly.Currently the number of mobile users is also alarmingly increasing,hence it is a matter of fact that the mobile companies are forced to give some value added services to the mob inorder to spread their network.Fortunately, the various schemes offered by the companies are more attractive which would gather momentum among the mass.However there are some loop holes in the present system which makes the current system inefficient in certain aspects.One among such is the roaming problem which is of very high concern.
In order to provide solution to this ,we propose a network that utilizes the current infrastructure with few modifications in the call routing technique.That is we include GPS receivers in each mobile handsets and also in the mobile towers.So, by this way the GPS system gets access to the individual mobile handsets and also their respective towers .Hence any call signaled is directly routed to the destination location without any unwanted routing with the help of the position information provided by the GPS system.This overcomes the overhead of long routing paths taken by the system (in case of roaming) even if the destination location is very nearer to the source.
This scenario requires nothing more than the implementation of GPS unit along with certain simple protocols to route the call efficiently.Fortunately although this system is proposed for roaming problem it is quite true that this scheme of routing is still more efficient and effective when compared to the present scheme.It is natural that people would bother about the cost of the receiver that is being used in this scheme,but it must be accepted that with the tremendous growth in technology ,the cost of the receiver is not a matter of serious concern.As quoted earlier the cost of the GPS receiver is already decreasing ,with the increase in demand it would further come down. MOBILE ROUTING WITH GPS:
First of all each mobile towers and every mobile handsets is equipped with GPS receivers.Thus the GPS system contains the database of all the existing mobile towers aswell as the mobile handsets.
The other phenomenon such as locating the mobile in the region of the tower,transfering the call from one tower to the other via cables etc remains the same ,except for a slight modification in the method of postioning the destination location,here is where the GPS system comes into picture .Let us consider the procedure of call routing to a destination mobile network from the source . Call made from the source mobile reaches the nearby tower at first.
The tower traces the called number by locating its position with the help of the information provided by the GPS system.
In the GPS system there are predefined set of algorithms that would identify the nearby tower of the destination mobile handset and signals it to the source. Thereafter the call gets routed to the destination via the normal procedure of routing employed in the current scheme by taking the shortest path available.
The calls that are routed by this scheme makes use of the position information provided by the GPS receiver effectively for efficient call transfer.It should be noted that the algorithms that we specify makes use of "Doppler shift" concept to locate the tower nearby to the destination mobile(ie)after locating the destination mobile with the help of the GPS position information the algorithm compares the "Doppler shift" of this destination mobile with the information of all the existing towers and thereby finds the tower which is very much nearer to destination mobile and then signals it to the source.After this ,as said earlier the call
GPS satellite
destination
source
Normal call routing technique
is routed to the destination with the usual method of call transfer technique PERFORMANCE ANALYSIS
' A specific example of a call that is made from Bangalore to a Chennai registered
user in Bangalore itself. Consider the present scenario for this case. The call gets first routed to the Chennai base station where the user has registered and then it comes to know that the user is in Bangalore. The call is again routed back to Bangalore. Since in
N ' GPS satellites
D
Chennai Base
Station Source Bangalore Base Destination
Station
Present Scenario of Call Routing
our proposal we totally eliminate such unwanted routings the system becomes more robust and economical
For the same case, our GPS equipped system can act as shown in figure . In the first phase the position of both the mobiles can be obtained from GPS satellites. Then the call is routed to the nearest base station of the destination through conventional methods. The base station then acts appropriately to establish the call.
The distance between Chennai and Bangalore is 350km. For the mobile routing scheme used now the established call would travel more than 700km making this worst case very inefficient.
Source Bangalore Base Destination Station
Call Management with the help of GPS As for the accessing of satellites in this scheme, it is simply going to use the co-ordinate position information and the call itself is never sent to the GPS. Hence the effective distance traveled is literally the sum of two sides of the triangle formed by the two mobiles and the base station. The above illustration points out the distance saved in call
routing. Once again with the decrease in the distance traveled the time taken also gets drastically reduced. Eventually this results in the reduction of call tariff.
As mentioned earlier, although the scheme we proposed was mainly for the roaming problem, fortunately the scheme proves to be a better solution for many of the mobile routing problems. The advantages of the scheme are
¢ Solution to the roaming problem
¢ Globalises mobile system
¢ Tracking becomes possible
¢ A scalable scheme
¢ Utilises the existing mobile network effectively
CONCLUSION
In this paper we have proposed a novel routing method for mobile networks which eliminates the various overheads involved in the current routing schemes. Besides, the paper proves to be a scalable one, making it possible for future expandability. Above all, it requires only a slight modification in the hardware of the current networks.
Our future course of work includes discovering new ways of exploring the cyberworld using the proposed technique.
REFERENCES:
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[6]T.S.Rappaport "Wireless communications rinciples and Practice",Pearson Education,2002.
[7].T.Viswanathan "Telecommunication switching systemsand networks",PHI,1994.
GPS EQUIPPED MOBILE ROUTING