Global Positioning System Tracking Solutions

Abstract

This article focuses on ways the Global Positioning System can be extended and applied for tracking systems solutions. It details the different types of tracking and how these can be implemented, from hardware to software architecture. Depending on the main activities in which can be used, there are also analyzed the benefits and improvements brought by this technology. As a innovative solution for this there is presented a tracking system based on mobile phones.

Keywords: global positioning system, tracking, architecture, types, solutions, mobile phones, benefits

Introduction in Global Positioning System tracking technology

GPS tracking system is a new technology developed nowadays as a result of development of Global Positioning System, Internet, wireless communication and 3S technologies. It is a great technological revolution on vehicle navigation field for solving the problems of vehicle management in recent years.

This concept of tracking is different than navigation concept. While navigation systems help the driver to reach the destination, the tracking systems use a base station (a server) to keep track of the vehicles without the intervention of the driver.

This new technology enable the tracking of all kind of mobile assets accurately and provide their real time position to the owners on a 24 by 7 basis over the GPRS/GSM link. While the GPS provides the latitude/longitude information of the mobile asset a given time, this information can be transmitted using the GPRS radio link, to any place.   

In fact, the asset can even have enough intelligence built into it to initiate calls using the GSM phone links and it can communicate with other systems, for example the vehicle systems and sensors, to provide complete information about that asset. Operators at the other end can also initiate calls to the mobile assets since these have the capability to conduct two way communications. The tracker functionalities are described in detail in [6].

The monitoring system combines an electronic device installed on the asset (which interacts with the GPS receiver) with a communications component such as cellular or radio transmitters and a purpose-designed computer software at least at one operational base to enable the owner or a third party to track the asset’s location, collecting data in the process from the field and deliver it to the base of operation.

These data could be stored in a database by the server for further reporting and analysis but the asset device could also have on board storage ability for a certain amount of data. Vehicle information can be viewed on electronic maps by the specialized monitoring software.

The technology and the cost of implementing this technology has come down drastically over the last few years making them very affordable to the general public.Integration of GPS and GSM technologies have been applied in many different fields such as Intelligent Transportation Systems, Logistic Management, Electric Power Distribution, Defense Security and Urban Planning to provide location information for various users, on electrical map. A detailed list of uses is described in [1].

This paper details the hardware and software specification of various components of the system and propose an architecture based on mobile phones.

Types of tracking and system architecture

Depending on the activities in which is used, this technology has been developed in two ways: passive tracking and active tracking.

Passive tracking, also named off-line tracking, is the most inexpensive and cost effective solution to make a full control of the assets, especially for vehicles. This type of monitoring system does not have any visible or hidden operating payments and not need any wireless communication network.

Passive tracking, is based on devices that store GPS location, speed, heading and sometimes a trigger event for other systems such as key on/off, door open/close. These types of trackers are called data loggers. Modern GPS loggers have either a memory card slot, or internal flash memory and a USB port. Once the asset returns to a predetermined point, the device is removed and the data is downloaded to a computer for evaluation. Passive systems include auto download type that transfer data via wireless download.

The collected information thereafter is automatically analyzed in personal computer by special software and displayed on electronic maps with details of moving, points of events and reports about asset’s activity.

As can be seen in (Figure 1) the passive tracking system architecture consists of three components.

Figure 1 – Passive tracking system architecture

First of them is the space segment which contains all the satellites that sends the special signals to the earth, which carry information about their exact positions in the orbit and are precisely synchronized with the moment of time that the signal is generated. Their orbital positions are organized such that, at any location on earth, without obstruction), at least five of them are guaranteed to be in the line of sight most of time.

The second component of this architecture is the tracking unit which is installed on the asset that is being monitored. This unit consists of three modules: GPS receiver, internal memory and microcontroller board. Based on satellites signals, GPS receiver determine all three dimensions of the asset’s current coordinates as well as the precise time.

The controller interacts with the GPS receiver, collects coordinates at predefined intervals, processes it and store it in internal memory. The unit could also interact with other systems, like vehicle sensors and systems and obtain various parameters (for example fuel level, error codes, engine status, tyre pressure, braking action, lack thereof) which is also stored in internal memory. Typically CAN bus interface is used as the communication protocol, and as such the hardware will be able to handle the bus protocol requirements. The software solution for this device is based on an embedded operating system like embedded Linux and XP-Embedded.

The third component in the architecture is the monitoring station which is a pc based computer with a special software that generate necessary reports and diagrams about asset activity and store the information in a database.

Active tracking, also named on-line tracking, is similar with the passive one, devices also collect the same information, but they transmit the data in real-time via cellular and satellite network to a data center for evaluation. At present GSM has been considered as an appropriate communication platform in GPS monitoring systems due to its numerous advantages in transfer short messages such as high frequency, reliability, high capability, open interface, strong ability of noise canceling, wide coverage and various types of business.

Many modern tracking devices combine both active and passive tracking abilities: when a cellular network is available and a tracking device is connected it transmits data to a server but when a network is not available the device stores data in internal memory and will transmit stored data to the server later when the network becomes available again. Active tracking is used by two type of devices: data pushers and data pullers.

Data pusher is the most common type of GPS tracking unit, used for asset tracking, personal tracking and vehicle tracking system. Also known as a GPS beacon, this kind of device sends the position as well as other information like speed or altitude at regular intervals, to a determined server. Data pullers are also known as GPS transponders. Contrary to data pushers, that send the position of the devices at regular intervals, these devices are always on and can be queried as often as required. These can often be used in the case where the location of the tracker will only need to be known occasionally. Examples of uses and applications for both types of devices can be found in [5].

The architecture of active tracking system is shown in (Figure 2):

Figure 2 – Active tracking system architecture

As can be seen the first component of the system, the space segment, is the same from passive tracking architecture. The tracking unit, that is installed on the asset, has also a GPS receiver which calculate the position, a microcontroller board which can communicate with other systems and sensors using CAN interface, but has also a communication link that allows data to be transferred to the monitoring station using HTTP/SOAP protocol over GPRS network. The monitoring station consists of several servers: application server that, on one hand, pass the GPS data to database server, and on the other hand take the requests from web server and assigns to GIS server and database server, the web server which acts as a bridge between clients and application server, the database server which store the information and GIS server which supplies some treatments of spatial data and transmit the result to client. The received information of vehicle will be displayed on the digital map and transmitted to user by web page which is composed of text and picture. An application developed based on such an architecture is described in [4].

Mobile phones based monitoring system

In this section a monitoring system architecture based on mobile phone is proposed. This is a full-featured low-cost GPS tracking system solution.

GPS tracking onto GSM/GPRS cell phones is convenient for private use, because of wide variety of GPS-enabled phones and tracking services available in present. It allows users to make the tracking right onto mobile phones. The operating principle of tracking system basically works the same. The GPS receiver built into the phone calculate the position based on satellites signals (latitude, longitude, altitude and accurate time) and then transmit the data to servers through GPRS network/wireless network for processing.

A N-tier model using mobile phones based architecture is presented in (Figure 3):

Figure 3 – N-tier model for mobile phones based tracking system

For this architecture the asset’s track device is the cell phone with GPS receiver built in. The receiver could be also a separate device which can communicate with the phone via Bluetooth or serial port. The main drawback from the others architectures is that cell phone cannot communicate with systems and sensors, like vehicle engine management system, so the users cannot track those information. Along with the evolution of cell phones capabilities, both types of tracking can be possible, depending on the client application. If the cellular network is not available, the application can store the data into internal memory and transmit later to the server, acting like a data logger, but when network is available, the data is send directly to the server. A platform for developing mobile GIS applications is discussed in [7].

This architecture enables system upgrades to cell phones remotely (both firmware and system software including applications) and enables the possibility of deploying additional services above the standard features on this phone as they become available or provide a simple upgrade to existing application services. Communication between phone and main server can be implemented using HTTP/HTTPS/SOAP protocols over the GPRS network/wireless network. Firmware and application updates from server to the client’s application will be using proprietary protocols implemented over standard HTTP/SOAP and the packets will be encrypted using SSL/HTTPS. A detailed software architecture for both client and server could be found in [5].

The monitor station part in our architecture is represented by three types of servers: database server which store and manage the GPS information in database, the application servers which process the data received from client application and passes to the database server but also receive the user’s requests and return the result based on the data from database, and web server which is a mediator between users and application servers. The web server also interacts with a Map Web Service (Google Maps API, Yahoo Maps Web Services) which provide the electronic map for displaying the requested data.

The Application servers runs two main applications: data receiver/provider web service which would be responsible for handling data from mobile phones and requests from users and firmware update application which would be responsible for sending firmware or application software updates to the cell phones devices.

The web service is not complex by definition and can be designed as a stateless service so that it can be scaled out to N number of servers to handle the simultaneous hits. Simple nature of this web service avoids the need for multiple threads, there by making it easier to scale up by adding more resource to the server if needed.

The firmware update application can be designed in such a way that updates do not happen on all the cell phones simultaneously. Hashing algorithms can be developed based on incoming MAC address or device ids so that updates can be distributed over time. This will avoid processing and network load on the gateway server, also these updates will use bandwidth of the telecom operator and thus increasing the cost of ownership.

The incoming data for one monitoring station usually have a high level. This could generate service failure (software crashes), system and hardware failure (disk crashes) and even site failure(natural disasters, power outages, network interruptions).

These problems could be avoided by applying one of these solutions. The first one consists in using of a network-load-balanced server cluster (NLB as can be seen in the architecture) which provides load balancing support and distributes requests across servers. A NLB can be configured in the Gateway Server cluster to distribute the network load among the server farm. Each of the cluster server can be configured to scale-up by increasing the system resources (CPU, memory) and scaled-out by adding more servers to handle future increases in data volumes, on demand.

Another solution for this problem is the multi-agent based technology. This technology implies the existence of several monitor stations that divide the monitored area into several sub-areas. Those agents have similar architecture and functions and are able to communicate and coordinate their activities with each other to trade information about the position of the object. The agents engage in negotiation with each other when the object moves to the area between the inner-circle and outer-circle.

As a software solution for our monitor stations we could use Windows Server 2003 because is an operating system that is designed to work in such distributed environment.

Aplicability and benefits of mobile phones based system

Once with development of mobile phones and their capability to incorporate GPS receivers, they have become a big attraction in the tracking industry. Until recently, global positioning tracking systems were made only with tracking devices that were very expensive and software hard to implement, as can be seen in the architectures presented above. Cellular technology came as a full-featured low-cost solution for this problem. Depending on the needs of the customer, the aplicability for such a tracking system based on mobile phones is wide.

The common use for this technology is the vehicle tracking, which is used by fleet operators for functions such as routing, on-board information and security and dispatch. For example a hospital could put such a tracker in every of its ambulances, thus allowing the operators to know in every moment which ambulance is the closest to the emergency point, this increasing the efficiency. This solution could be useful for all kind of companies, so they can cut down their fuel expenses. Also this category of applications could incorporate the stolen vehicle searching. The owner of the car could put a mobile phone in a secret place in the car and could activate it in case of theft. The cell phone acts, in this case, as a data puller and the activation is made when a SMS is received with a specific command.

A drawback in using mobiles phones in this case as a tracking device is that it cannot communicate with the vehicle management system and it cannot track some parameters that other tracking units can.

The tracking technology based on mobile phones could also be used in locating people in an Emergency. For example, when a call to one emergency number is made, the tracking application automatically send the current location to a server so that person is easier to find.

Related to the people usage, there are many ways to use this technology and can be applied anywhere. For example tracking kids and the elder, private detective purpose, tracking pets, private mobile luggage or private cars or motorcycles. Those applicabilities are detailed in [1] and [2].

Another uses for tracking systems based on cell phones are the concerns about GIS applications. A user can register routes, maps, points of interests, can managed them in the database and can share them with others.

The benefits of such an architecture like the one proposed in this paper is evident.
First, the difference is made by the price, cost for hardware and software necessary for the system. Since more and more cell phones are outfitted with GPS receivers, they can be cheaply transformed into a GPS tracker. The cost for communication over GPRS is also low: about 1Kbytes of data over each minute that means about 50 Mbytes in one month. These sent data could even be reduced by specialized algorithms for redundant connections by removing the redundant transmissions. In this way location updates could be reduced and energy from phone battery saved. Some of these algorithms are presented in [3].

The capability to store the data in internal memory or on a memory card is also a feature that every cell phone has. Also the costs for installation the tracking device in the asset is removed. On the server side the cost for the company that implement such a service is also lower than other types of architectures because the GIS server was replaced with a free MAP API. The network-load-balanced server could be installed optionally but his price will be quickly amortized in time.

Another benefits of using mobile phones as tracking device is the high portability. Since most people and organizations have cell phones with them all the time, this has became a preferred solution instead of classic tracking units. This also offer other areas of uses that classic devices didn’t.

The most interesting feature for a tracking system based on mobile phones is that users, those who monitor/manage the tracking units could be also a mobile phone. This make possible for two or more persons to communicate with each other and they could even monitor reciprocally, which doesn’t happen with a standard tracking device.

Conclusions

GPS tracking systems have evolved quickly in the last few years and are going to be commercialized all over the world in a decade, because of its advantages in all areas: marine, air and land transport. Also, the evolution of cell phones and their integration with GPS technology makes them the perfect solution for such a tracking system.

This type of system, both in case of personal uses as well as business purpose, improves safety and security, communication medium, performance monitoring and increases productivity.

As this happens we are going to see even more ways of using this innovative technology and new applications which covers a wider range of activities.

The conclusions of this study consists in the results that tracking system developed can provide for both users, that monitor the  mobile units, and clients.

In this paper, an architecture model for a GPS tracking system based on mobile phones is proposed. It’s a client-server model which combines GPS technology, GSM technology and WEB technology. It affords an easy and convenient method for users to monitor and manage a number of clients directly from a web interface or even from another mobile terminal.

It is also a flexible and expandable system architecture that can be easily customized and scaled to support any configuration to suit a variety of applications.

Compared to classic architectures, cell phones based system is more portable and removable, with a low cost and full featured, and the servers are better organized to handle a large volume of data.

As the next step, this research has to be designed in more detail and the solution must be implemented as per each customer requirements.

References

[1] GPS Tracking Today, How To Use GPS Car Tracking Systems, 2010, Accessed at:11/15/2010, Available at:http://www.gpsfortoday.com/how-to-use-gps-car-tracking-systems/

[2] Leroy Hasson, What GPS Tracking System Can Do For You, 2010, Accessed at:11/15/2010, Available at:http://dropshipping.co.za/2010/09/09/gps-tracking-4-you/

[3] Bing-Fei Wu, Ying-Han Chen, Chao-Jung Chen, Chih-Chung Kao, Po-Chia Huang, An Efficient Web-Based Tracking System through Reduction of Redundant Connections, Advances in Neural Network Research and Applications, 67 , 7 , pp.671-677, 2010

[4] Cheng Qimin, Yang Chongjun, Shao Zhenfeng, Liu Donglin, Gao Liang, Design and implementation of webGIS-based GPS vehicle monitoring system, Geo-Spatial Information Science, 7 , 2 , pp.96-100, 2004

[5] Miguel A. Labrado, Alfredo J. Pérez, Pedro M. Wightman, Location-Based Information Systems: Developing Real-Time Tracking Applications, Routledge, USA, pp.4-50, 2010

[6] D.P. Brown, Ultimate Guide to GPS Tracking Systems, Learning Life eBooks, USA, pp.15-60, 2008

[7] Lucian Zavate, ArcGIS Mobile – Accesibilitate si Mobilitate, A XVI-a Conferinta a Utilizatorilor ESRI si Trimble, 25-sept 2009, Bucuresti, Romexpo, Conferinta Utilizatorilor Esri, Trimble si ENVI, ESRI, Bucuresti, pp.22-27, 2009

License

This article, along with any associated source code and files, is licensed under The Intelliproject Open License (IPOL)

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