Bus Management System Using RFID In WSN

European and Mediterranean Conference on Information Systems 2010 (EMCIS2010) April 12-13 2009, Abu Dhabi, UAE

Bus Management System Using RFID In WSN Ben Ammar Hatem, Faculty of Engineering, University of Moncton, NB, Canada,[email protected] Hamam Habib Faculty of Engineering, University of Moncton, NB, Canada, [email protected] Abstract In this paper we present a novel approach to integrate RFID (Radio Frequency IDentification) in WSN (Wireless sensor network). WSN is used to support RFID identification process by extending the read range of an RFID system. Besides, by the use of the WSN we can monitor the environment of an object and optimize RFID reader’s performance and energy. Then, methodology to integrate RFID technology, wireless sensor network to form an intelligent bus tracking application is studied. The proposed system can monitor bus traffic inside spacious bus stations, and can inform administrators whether the bus is arriving on time, early or late. This information is then displayed on the different wireless displays inside and outside the bus station. Keywords: RFID, WSN, Zigbee, integration, tracking, buses

1.

INTRODUCTION

Nowadays, travel time information becomes a major component of Advanced Traveler Information System (ATIS) [1]. The travel time of buses varies depending on several external parameters such as traffic, snow and accidents. In fact, buses are stuck in traffic and are thus hampered by the passage of junctions. This makes the management of the bus schedule in the bus stations a difficult task. Most bus station follows fixed schedules, and don’t uses intelligent systems for vehicle tracking and control. Many supervisors are deployed at the station to control the entrance and the exit of buses and prepare the trip sheets containing the schedules manually which is time consuming and inaccurate. Moreover, transport departments have no visibility over utilization of its fleet on real-time, which results in underutilization of resources. So, all these naturally results in avoidable stress, costly errors and sub cost optimal fleet utilization and finally dissatisfaction and inconvenience to millions of commuters. The provision of timely and accurate transit travel time information is so important. New technology can help the administrator to monitor the buses traffic while increasing the satisfaction of transit users and reducing cost through efficient operations asset utilization. Well-known examples of identification technologies include Closed-Circuit Television (CCTV) and Global Positioning System (GPS). CCTV can be deployed at each entrance gate and image processing techniques can be utilized to identify the arrival of buses [2, 3], where image recognition was performed to detect the bus in the traffic. Results from this testing has shown poor performance in tracking based detection (~20% precision). During the past, GPS integrated to Geographic Information Systems (GIS) was used to monitor buses traffic [4]. GPS receiver communicates with at least 4 satellites before giving the position of the bus. It gives a very good precision; however, line of sight between the receiver and the satellites is required otherwise the GPS signal is attenuated. This is a main limitation of this technology especially when it comes to monitor bus traffic inside an underground bus station. Hatem Ben Ammar and Habib Hamam. Bus Management System Using RFID In WSN

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Due to the limitation of these technologies, RFID can be used to track buses. This technology can be effectively applied for real-time tracking and identification [5]. RFID was developed in the 1940s by the US department of defense (DoD) which used transponders to differentiate between friendly and enemy aircrafts [6]. Since this time, RFID technology has been evolving to change the way people live and work. Many previous research projects have explored the possibility of integrating RFID in different areas, from toll collection [7], agriculture [8], access control [9], supply chain [10], logistics [11], healthcare [12], and library [13]. RFID technology can response to our tracking needs that’s why we used RFID in our design to identify buses entering and leaving the bus station. In this context, this paper presents the developments and the results of a research project on bus tracking based on the use of RFID technology and WSN. These two techniques are combined to support identification process by extending the read range of an RFID system and improving its performance.

2.

RESARCH METHOD

The main idea of our research is to integrate RFID technology and WSN to build an intelligent bus tracking system. Two scenarios of integration have been implemented. In the first one, we have extended the read range of the RFID system by adding wireless facility to RFID readers. Each RFID reader is equipped with a wireless module which can transmit data to and from the reader. RFID reader acts as sensor node: it reads the identification of an object and sends it to the host application via an ad-hoc network. The second scenario of integration provides RFID readers with sensing ability. Several motion sensors are installed near each reader to detect the presence of a tagged object and to command the reader activity. This approach is tested through an application which can track buses traffic in the bus station. When designing this system, the following constraints have been considered: -

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3.

Modularity and expandability constraints: the system must be modular in design. Both hardware and software should be divided into small components or modules to ensure easy scalability for further feature expansions. Modules must be produced independently from each other, so that changes or the crash of one module cannot affect the other ones. Economic constraint: We should take into account performance to cost ratio so as to design a cost-effective solution Environmental constraint: In our design and implementation, we should keep in mind the impact on environment. Low power consumption devices should be used to keep the power of the system very low. Energy optimization should be involved in all the design’s steps.

RFID TECHNOLOGY

Traditional RFID system consists of three main components (Figure 1):

Figure 1: General RFID architecture

Hatem Ben Ammar and Habib Hamam. Bus Management System Using RFID In WSN

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RFID Reader: sends an electromagnetic wave which carries a signal to identify objects. Then, the reader receives the information returned back by these objects. - RFID tag: attached to these objects, reacts to receiving the signal sent by the reader in order to forwarding to it the requested information. - A computer/database: stores and processes information collected by the reader. Traditional RFID readers are imitated in their mobility and their potential applications they are usually connected to the host application via a serial port or via Ethernet.

4. 4.1

INTEGRATION OF RFID AND WSN Wireless Sensor Network

Installing cables to ensure communication between RFID readers and the host application is very challenging especially in spacious space. Also replacing defective wiring can be extremely difficult and more costly compared to wireless communication. To address these issues, we propose to connect wirelessly RFID reader to the host application. There are many wireless technologies that can be used such as Bluetooth (802.15.3) and ZigBee (802.15.4) to extend the range of an RFID reader. Bluetooth has been standardized by IEEE 802.4.15. It allows the creation and maintenance of short range Personal Area Network (PAN). Bluetooth transfers data at the rate of 1 Mbps, the range of Bluetooth device is about 10 meters. The main defect of this technique is its high energy consumption and therefore cannot be used by sensors that are powered by a battery. IEEE 802.15.4/Zigbee standard [14] offers even better features that meet the needs of WSNs in terms of energy saving. While ZigBee offers lower data rates it consumes much less than Bluetooth. A low data rate does not handicap our wireless network where the operation frequency is low. Besides, one of the main advantages of ZigBee is its ability to "mesh". Mesh networks enable messages travelling from node to node and arrive to their destination even if one node fails. It also provides easy maintenance, and can cover large areas [15]. This makes ZigBee an excellent choice for our WSN. Moreover, the low cost allows the technology to be deployed at various spot in the bus station to ensure a reliable data transmission. Xbee PRO serie 1 module has been selected. It is characterized by a range of 10 to several hundred meters and a speed of 20 to 250 kbit/s4.2 Sensing the environment of the reader 4.2

Sensing the environment of the reader

The RFID reader is always inactive. Once a labelled object approaches to the reader, the first motion sensor detects its movement and an event is sent to the software application via a Zigbee module by using UART (Universal Asynchronous Receiver and Transmitter). The event is handled by the RFID middleware and a command is sent back to the RFID reader to enter in the read mode. Then, the RFID reader reads RFID tag attached to the object and sends its identification (ID) to a Zigbee module which will relay it to the central computer. Once the object passes the second sensor, the reading is stopped and the reader returns to the idle mode (figure 2). Alien ALR-9800 RFID reader has been chosen in our implementation. It provides a flexible general-purpose input-output (GPIO) system which enables tight integration with external sensors. Two motion sensors has been wirelessly connected to the reader’s GPIO to detect the presence of an object. The AMN1 motion sensor was selected because it provides a better detection range (5m). Motion sensors are accessed by the RFID middleware (which is Hatem Ben Ammar and Habib Hamam. Bus Management System Using RFID In WSN

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implemented in the host application) and are used to control the reader activity and to optimize its energy. RFID Reader Motion sensor 1

Motion sensor 2

Zigbee module (End device)


GPIO

UART


1 : object detected

host application Usb / RS232 Zigbee module (coordinator)

1 : GPIO event 1 : Start reading 1 : object detected

1 : GPIO event 1 : Stop reading

Figure 2. Reader’s energy optimization

5.

BUS MANAGMENT SOLUTION

Our aim was to develop a real-time schedule tracker system which can inform administrators whether the bus is running on time, ahead or behind schedule. This information is then displayed on different displays at the bus station to offer better services to the passengers. It also gives operator the opportunity to make dynamic changes to the schedule time so he/she can optimize the utilization of its fleet (buses). To enable such automation in the bus station it is necessary to identify the arriving and departing buses. In this section, we present system architecture to monitor buses traffic, integrating WSN and RFID. 5.1

Design approach

Entrance and exit doors are equipped with an RFID reader, antennas and motion sensors. Each bus has a UHF tag, which is applied inside the windshield. With this system, we can monitor the buses traffic in real-time and without human intervention. Each time, a bus enters or exits the station, the RFID reader sends its identification to the central computer where the event is displayed on a Map. So the supervisor no longer needs to move on place to check the arrival of bus. Besides, this system provides a dynamic display inside and outside the station. It advertises customers to move outside the station to check the arrival of the bus. Each quay (bus stop) is equipped with a display which is connected wirelessly to a control station. A software application on the control station keeps track of the entrance and the exit of buses and updates the displays related to those buses with helpful information. Figure 3 shows the main components of our system.


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Led Matrix display in the waiting room Database

Timer

Entrance gate Antennas

Central Computer

Wireless Sensor Netowrk

RFID Reader

Motion sensor

UHF tag

Exit gate Quay display

Figure 3. Bus station schedule management solution using RFID and WSN

Displays are used to provide passenger with real-time information about buses such as time remaining and the next trip. They must be deployed on each quay in the bus station and must ensure effective display of information. LCD and LED technology could be used. LCD displays provide powerful display capability with up to 16 million colors but they are typically higher cost than LED based displays. As we are limited to displaying simple alpha numeric characters, LED display has been selected. We choose UHF Gen2 (Ultra High Frequency generation 2) RFID which operates between 860MHz to 960MHz bandwidth [16]. UHF is better suited for reading tag attached to buses. It uses backscatter technique to communicate with the tag and provides higher read range compared to HF and LF technology. In our design, we used Alien circular antenna to read RFID tags regardless of orientation. Two antennas are used in each gate, to communicate with tags. One ensures the emission of energy to the tag and the other receives energy back from the tag. 5.2

Software contribution

Bus station schedule management software application eliminates any human involvement. It dynamically manages the time table and bus dispatch for optimum ride ship. It wirelessly controls Hatem Ben Ammar and Habib Hamam. Bus Management System Using RFID In WSN

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displays and can also generate auto statistic report. It will automatically alert administrator in case of any bus’s late arrival. The software includes six modules: Wireless Sensor Network Communication, WSN Middleware, RFID Middleware, Display Management, Database Interface, and User Interface. Figure 4 shows the architecture of our software.

Dynamic Graphique User interface

DB

Database interface

Application code

XML interface description

Inside Displays RFID Middleware

Display Management Quay Displays

Wireless Sensor Network Middleware Wireless Sensor Network Communication Figure 4. Architecture of the RFID based Schedule bus management software

The Wireless Sensor Network Communication layer implements Zigbee API communication protocols which encode/decode data in a formatted packet and supports data buffering, overflow and transition error control. The API mode is then used to identify the packet’s origin and to detect packet loss. Wireless remote configuration is also permitted by this mode so we can remotely manage our network to ensure best operation. The Wireless Sensor Network Middleware allows our application to communicate with different types of wireless devices. It serves as a gateway between the application and hardware devices and it is responsible for delivering all Zigbee traffic to the application. Displays and readers communicate with the WSN middleware to deliver data to and from the application. An RFID middleware manages RFID readers and accesses to their GPIO. It also manages received data from RFID readers by filtering and transforming them into useful data. By implementing the RFID middleware, management and the configuration of RFID devices are separated from the application. The database contains general information about buses and range of RFID identification numbers referred to them. The database stores also different information about displays and Zigbee modules. Each display is identified by an ID number queried by the microcontroller which constitutes the Display’s processor. Zigbee transceivers are identified by their MAC addresses (64bit number). The database interface provides access to the data using SQL (structured query Language) and enables the data to be easily presented. Display management module for the update and the configuration of remote displays using XML schema. Hatem Ben Ammar and Habib Hamam. Bus Management System Using RFID In WSN

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6.

CONCLUSION

RFID reader integrated with WSN will benefit from communications and sensing capabilities. The integration of the RFID and WSN will facilitate the extension of an RFID network eliminating the need the need of wired installation while reducing cost and saving time. The mix of these two promoting technologies has been explored in this article to provide a smart solution managing the bus schedule in the bus stations and offering helpful information to passengers. It is believed that by the implementation of this system, problems such as underutilization of buses fleet and long waiting time at the bus station will be reduced. So, both passenger and bus station administrators will benefit from the system as real time information are provided. It is expected that integration of RFID and WSN will provide new opportunities for applications related to the identification of object over a large area. Possible applications of RFID with wireless capability include parking solution, agriculture and forklift trucks in the supply chain.

References [1] Ran Hee Jeong, and Laurence R. Rilett (2004) “The Prediction of Bus Arrival Time Using AVL Data”, Transportation Research Board 83rd Annual Meeting, Washington D.C. [2] Mark Cracknell ( 2007) “Image detection in the real world ” , Intelligent Transportation Systems ITS’07 Aalborg. [3] Mark Cracknell (2008) “Image detection in the real world ” , Intelligent Transportation Systems World Congress ITS WC 2008, New York. [4] Qing-Jie Kong, Yikai Chen, and Yuncai Liu,(2009) "A fusion-based system for road-network traffic state surveillance: a case study of shanghai," IEEE Intelligent Transportation Systems Magazine, vol. 1, no. 1, pp. 37-42, [5] Sheng, Q.Z., Li, X. and Zeadally, S. (2008) “Enabling Next-Generation RFID Applications: Solutions and Challenges”, IEEE Computer, Vol 41 No 9, pp 21-28, [6] Ollivier M., (1995) “RFID- a new solution technology for security problems”, European Convention on Security and Detection, 408, pp. 234-238. [7] Jae-Bong Yoo, Byung-Ki Kim, Ho-Min Jung, Taewan Gu, Chan-Young Park, Young-Woong Ko. (2008) “Design and Implementation of Safe & Intelligent Bridges System Based on ALECompliant RFID Middleware in USN”, Fifth Internationnal Conference on Computer Science, Rome, Italy, Vol 2 No 2. [8] Athanasios S. Voulodimos, Charalampos Z. Patrikakis, Alexander B. Sideridis, Vasileios A. Ntafis, Eftychia M. Xylouri (2009) “A complete farm management system based on animal identification using RFID technology”, Computers and Electronics in Agriculture. [9] Valentin POPA, Cristina TURCU, Vasile GAITAN, Cornel TURCU, Remus PRODAN. (2006). “Optimizing Campus Access and Services Using RFID Solutions”. The 8-th International Conference on Development and Application Systems, pg. 228-233, ISBN (10)973-666-194-6, Suceava, Romania. [10] Goebel, C.; Tribowski, C.; Günther, O.; Troeger, R.; Nickerl, R ( 2009) ”RFID in the Supply Chain: How to Obtain a Positive ROI - The Case of Gerry Weber”, Proceedings of the 11th International Conference on Enterprise Information Systems (ICEIS 2009), Vol. Information Systems Analysis and Specification, pp. 95-102, Milan, Italy, [11] Werner, K., Schill, A ( 2009) “Automatic Monitoring of Logistics Processes Using Distributed RFID based Event Data”, 3rd International Workshop on RFID Technology 2009 Concepts, Applications, Challenges (IWRT 2009), Milan, Italy Hatem Ben Ammar and Habib Hamam. Bus Management System Using RFID In WSN

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[12] Lewis, M, Sankaranarayanan, B, Rai, A ( 2009) "RFID-Enabled Process Capabilities and Their Impacts on Healthcare Process Performance: A Multi-level Analysis," in European Conference on Information Systems, [13] Fennani, and H. Hamam (2008) “An Optimized RFID-Based Academic Library”, SensorComm 2008, The Second International Conference on Sensor technologies and Applications, Vol 2008, 44-48. [14] ZigBee Alliance, ZigBee Specification, ZigBee Document 053474r06, version 1.0, 2005. [15] P. Brennan, S. Daugherty, A. Hughes and S. Vemuru (2008) “Designing a Wireless Personnel Tracking System”, ASEE NCS Conference Agenda. [16] EPCglobal Specification for RFID Air Interface, "Radio-frequency identity protocols class-1 generation-2 UHF RFID protocol for communications at 860 MHz - 960 MHz," version 1.0.9, Jan. 2005.


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