Mobile phones used inside monitoring and control systems.

Bujdei, Catalin ; Moraru, Sorin Aurel ; Dan, Stefan 等

Abstract: In this paper we will describe how mobile phones can be used inside monitoring and control systems. We will describe the architecture of such a system and the communication ways between the elements that form the system. Also, we will present the advantages of using mobile phones instead of other devices and the optimizations that could be implemented into the system.

Key words: mobile, monitor, control, system.

1. INTRODUCTION

The mobility of the people is a problem that was always been analyzed by the research groups. For this problem are found solutions, not complete solution, but optimized solutions of the existing ones. Always some obstacles will remain to pass for reaching the full mobility without any disadvantages.

The mobile phones offer to the peoples the possibility of mobile communication. At the beginning of the mobile phones they were dedicated only for voice communication. They were complex equipments, hard to use, expensive and with many problems to be solved. Nowadays the mobile phones become more robust, simpler implemented, more advanced technologically, cheaper and with many possibilities to offer to the user. The voice communication service remains and a lot of other new services have been included. The mobile phones are equipped with visual interface software, which allows the user to interact in an easy way with these services.

The companies which ensure the mobile communication into their own network develop more and more services, which could be used by the clients, or improve the existing services. The new services are implemented by the companies for helping the user but also as a market strategy. These services must be also supported by the mobile devices.

Most of the mobile phones users don't know the real potential of these services or they don't need to use more than a little part of these possibilities.

In Romania and in other countries the mobile phones are used frequently by lots and lots of people; they represent a good opportunities for use them instead of laptops or desktop computers. The biggest advantage of them is the mobility. The mobile phones are not such powerful as the computers but they could offer a big part of the possibilities offered by the computers. The mobile phones from nowadays could be considered little computers. They have some limitations, compared to the real computer, such follows: not so big computing power, little memory capacity, reduced screen size, low rate communication capacity, limited power energy, etc. The capabilities offered by them are enough for not very complex software applications. One possibility is to use the mobile phones into the systems of monitoring and control. They could represent the interface between user and the rest part of the system. The user could view status of the system, view data recorded by the system (monitoring) or interact with the system (control). For business people or companies the mobile phones represents the potential that they need for ensure remote monitoring and control of their systems (Sjodin, 2001).

2. CURENT STATUS IN THE AREA

Different projects was developed and implemented into the industrial or medical areas. The areas of implementing could be considered unlimited. The most of them use the Pocket PCs or PALM equipments for ensure the interaction with the end user (Ng et al., 2004; Hashmi et al., 2005). The problem is that in our country and in more other countries the use of these kinds of devices is not so common. In our country the people are used to use mobile phones devices as a solution for accessing different services, as Internet connection. It is better to adapt the applications for this type of devices than teach the people to utilize another type of devices which also requires supplementary costs.

Some solutions supposed to use mobile phone as an equipment which to collect the recording data and send them forwarded to the database (Proulx et al., 2006; Chen et al., 2005). The problem in such case is that the mobile phone processes lot of information and its energy decrease very quickly.

3. THE PROPOSED SYSTEM ARHITECTURE

A system dedicated for monitoring and control should be formed by:

* a hardware configurable network which could include recording elements and also action elements. The elements from the network should have installed software applications corresponding with their goals.

* a database computer which to be used for storing the recorded data. It's possible that the user to want to view not only instant values but also to see a history with data recorded in the past. This is the reason why it is necessarily to have a database.

* a client application accessible from Internet, as a web page or as application dedicated for mobile devices.

[FIGURE 1 OMITTED]

One example of system architecture, developed for have the best performances, in most of the cases, is presented into Fig 1. The monitoring and control network communicate with a Server computer using the Internet network. It is also possible to use a Local Area Network (LAN). On the Server computer it is installed a Server application, which collect data from the monitoring network. All the data collected are inserted into the database. As database, it could be used Postgresql or MySQL. Both of them are free application with very good performances. The Server application will be also the one that send the data to the client application. The Client application is installed on the mobile phone. The Client application make a request to the Server application and the Server application send back the data corresponding to the request. All processing of the data will be made by the Server application. The Client application only presents data in different formats and permits the user to send commands. These commands will be interpreted by the Server application and executed.

In this way the Client application is simplified, since the Server computer makes all the processing and data storage. Displaying some graphics and commands on the mobile device doesn't require much power processing or a lot of data processing. The energy consume is also reduced in this case. The single problems that remain are the screen size and the costs of the connectivity.

For the development of the Client application could be used the Java Platform for Mobile Devices (J2ME) or C++ for Symbian. In the first case the solution is possible for the mobile phones compatible Java. The second solution is only available for the mobile phones that have included the Symbian OS. The mobile phones with Java platform included are more than the ones with Symbian OS, so the first method is preferable to implement since much more people could use it.

At the developing of the Client applications dedicated for mobile phones it is preferable to define controls which to be reusable. The Java platform doesn't include many user interface controls and it doesn't include specific controls for the industrial or medical domain, for example. These controls could be defined as Java classes and then reused in every similar project. For example, we could have a specific control to represent a graphic (Fig. 2) or specific control for display industrial equipments, medical equipments, etc.

[FIGURE 2 OMITTED]

It is possible to implement, in the future, an archive that contain all the components developed, to attach a documentation and to allow other developers to use this components. It will decrease their development time.

4. OPTIMIZING THE SYSTEM

Planning the user interface taking in consideration these restrictions could solve the problem that refers to the screen size. Nowadays the mobile phones offer enough resolution that permits to the applications to display images big enough, to draw graphics or display many controls interfaces into a single page.

The cost of the communication is another major parameter that must be optimized. Since the data communication is paid at the amount of data transferred, the best way to do this is by decreasing the amount of data that is transferred from the Server application to the Client application. One solution is to use a compressing method for the data transfer.

The data in compressed before to be transmitted to the Client application. On the client side the data is received, decompressed and then used by the application.

In one application, dedicated for m-learning, we have used the RLE (Run Length Encoding) compression with enough good result. The RLE is a lossless algorithm that offers decent compression ratios in specific types of data. In that application packages of data, from a wav file, was compressed using RLE. The compression rate was in the interval 10%-50% depending on the package characteristics. The speed of compression is quick enough for not influence the data transmission speed. It is a simple to implement algorithm. Even it doesn't obtain very big compression rates its advantage is that it is very quick. Into the applications that require quick response from the Server application, using this compression algorithm is the best solution. If the time is not so important for the user then another compression algorithms more complex and with bigger compression ratios are recommended to be used.

5. CONCLUSION

The architecture developed could be used into any system of monitoring and control. In the future we want to implement this system together with a Wireless Sensors Network (WSN) for the medical domain. The role of this system is to monitor the health status of the patients. The mobile phones will have the role to display the parameters of the patients and eventually to display alerts when it is necessarily.

6. REFERENCES

Chen, W.; Tokinoya, S. & Takeda, N. (2005). A Mobile Phone-based Wereable Vital Signs Monitoring System. Proceedings of the 2005 The Fifth International Conference on Computer and Information Technology, ISBN: 0-7695-2432-X/05, sept. 2005, IEEE Computer Society, Shanghai

Hashmi, N.; Myung, D.; Gaynor, M. & Moulton, S. (2005). A Sensor-based, Web Service-enabled, Emergency Medical Response System. Proceedings of the 2005 workshop on End-to-end, sense-and-respond systems, applications and services, ISBN: 1-931971-32-3, 2005, USENIX Association, Berkeley

Ng, J.; Lo, B.; Wells, O.; Sloman, M.; Peters, N.; Darzi, A.; Toumazou, C. & Yang, G.Z. (2004). Ubiquitous Monitoring Environment for Wearable and Implantable Sensors. Proceedings of the 6th International Conference on Ubiquitous Computing, sep. 2004, Nottingham

Proulx, J.; Clifford, R.; Sorensen, S.; Lee, D.J. & Archibald, J. (2006). Development and Evaluation of a Bluetooth EKG Monitoring Sensor. Proceedings of the 19th IEEE Symposium on Computer-Based Medical Systems, ISBN-ISSN: 1063-7125, 0-7695-2517-1, 2006, IEEE Computer Society

Sjodin, M. (2001). Remote Monitoring and Control Using Mobile Phones, Available from: http://www.mrtc.mdh.se/publications/0568.pdf Accessed: 2007-02-20