RFID-based positioning systems for enhancing safety. and sense of security in Japan

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1 Draft for the paper published in: Proceedings of the Second International Workshop on Ubiquitous Pervaseive and Internet Mapping (UPIMap 2006), Seoul, Korea, October 23-25, RFID-based positioning systems for enhancing safety and sense of security in Japan Kaoru Sezaki and Shin ichi Konomi Center for Spatial Information Science, the University of Tokyo Abstract RFID technology provides us with an economically feasible means to build reliable positioning infrastructure at scale, which can be used to implement safety-enhancing applications for citizens. Embedding computing and communication capabilities in our physical and social environments imposes unique challenges in all aspects ranging from hardware deployment and positioning algorithms to understanding people s processes and practices in everyday and emergency settings. This paper describes our approaches to designing and building the software substrate for an envisioned national infrastructure in Japan, which aims at enabling ubiquitous safety-enhancing services by deploying RFID location markers across the nation, developing novel positioning mechanisms, and providing key application services. Key words: RFID, positioning systems, safety, sense of security, ubiquitous networks 1 Introduction Ubiquitous computing and mapping technologies have substantial potential to improve people s quality of life. RFID technology, in particular, provides us with an economically feasible means for building a ubiquitous computing infrastructure at scale, which can be used to implement varieties of application services. We can classify RFID-based systems into three generic types based on where RFID tags are attached or embedded. The first type assumes that people carry RFID chips in the forms of RFID train passes, payment cards/tokens, electronic passports, wristbands, implants, and so on. The second type embeds RFID tags in physical objects around us, creating so-called Internet of Things. The third type embeds RFID tags in physical spaces where people live, work and play. There are numerous real-world deployments of the first and the second types such as Wal-Mart s global RFID supply chain network

2 (Roberti, 2003), JR East s SUICA train passes, Transport for London s Oyster cards, and Mitsukoshi s consumer-facing RFID implementation (Konomi and Roussos, 2006). Our focus is on the third type, which has only been tested in small scale experiments, partly because of the high cost to embed RFID tags in physical spaces, limited hardware and software capabilities, and the lack of standardization and established practices. However, its substantial potential has been demonstrated in pilot projects for enabling robust information sharing for disaster relief using writable RFID tags (Takizawa et al., 2004), supporting firefighters in deep underground areas using RFID emergency exit signs, supporting location survey workers using RFID location markers (Matsuzaka et al., 2005), and assisting visually handicapped people using RFID tags buried under sidewalks (Ubiquitous ID Center, 2006; Fukasawa et al., 2005). Car navigation systems, GPS-enabled mobile phones and location-based services (LBS) are becoming increasingly popular among car drivers and pedestrians. However, existing location technologies can only provide limited support for critical applications that serve Japanese society s demand for increased safety and sense of security. We believe seamless high-precision positioning systems will enable a range of new applications that have substantial positive impacts on people s quality of life. The meanings of seamlessness in this context are threefold: (1) continuous availability of high-precision location information anywhere at any time including indoor and outdoor spaces, (2) integration of various data including low-level data captured through distributed RFID readers, GPS receivers and sensors as well as digital maps and high-level application data that embody relevant domain knowledge, and (3) communication and collaboration among people and organizations involved in research, development, deployment and use. We set out to achieve this seamlessness using RFID tags embedded in physical spaces. Embedding computing and communication capabilities in our physical and social spaces (Hutchins, 1995) imposes unique challenges of hardware and software deployment, positioning algorithms, communication protocols, distributed data management, ubiquitous service availability, fault tolerance, system integration, security and privacy, context-awareness, usability, and co-evolution of technologies, processes and practices. Moreover, this project is eliciting collaborative efforts among major academic and governmental stakeholders including Center for Spatial Information Science of the University of Tokyo, Geographical Survey Institute, National Institute of Information and Communications Technology (NICT), National Research Institute of Fire and Disaster, and National Research Institute of Police Science. These organizations had been independently carrying out related research and development before the project brought them together to explore a common framework for RFID-based positioning and location-based services, and pave the way to creating a social capital that would exploit a massive amount of RFID tags embedded in the land of Japan.

3 2 Related works Researchers developed prototype positioning systems utilizing RFID and other technologies so as to overcome limitations of GPS technology. However, none of them is efficient and reliable enough to serve our purpose. Companies and the government proposed various ways to use wireless identification and location technologies to facilitate rescue tasks after a disaster, an accident, or a crime. Such technologies are sometimes used to implement preventive measures as well. However, the design space for these safety-enhancing applications is relatively unexplored; state of the art technologies are too limited to support even simple safety-enhancement scenarios; and the technologies adverse effects such as privacy violations could make any of the technologies benefits irrelevant. Still, we can learn from existing works carried out by academics, companies and the government in the following areas. 2.1 Positioning systems Currently, GPS is widely used in systems that provide location-based services to consumers. However, GPS s inability to operate in indoor and some outdoor spaces (e.g., urban canyons) inhibits us to implement applications that must be able to support people anywhere at any time. Researchers proposed complex systems that combine GPS receivers and complementary sensors (Ono et al., 2004) in a limited scale so as to continuously provide location information indoors and outdoors. Ministry of Land Infrastructure and Transport s Mobility Support Project embedded inexpensive RFID tags in textured paving blocks and experimented with a high-tech white cane that senses the tags and provides auditory information for assisting visually handicapped pedestrians (Ubiquitous ID Center, 2006; Fukasawa et al., 2005). This project has demonstrated a unique possibility of a simple and inexpensive positioning system that could be deployed at scale. The ministry is also embedding RFID tags in location markers to assist surveyors (Matsuzaka et al., 2005). 2.2 Localization and communication techniques Researchers in the sensor networks and robotics areas proposed various localization techniques in the past several years (Hu et al., 2004). However, many of the techniques heavily rely on conventional technological settings such as wireless LAN or GSM mobile phones and cannot effectively exploit embedded RFID location markers, integrate GPS and geographical data, or allow mobile devices exchange positions and mutually improve positioning accuracy. Location information is highly useful for disseminating emergency information as well as collecting environmental data. Existing ideas to use sensor and ad-hoc networks for data collection and dissemination do not consider availability of RFID location makers and the like. Therefore, it is insufficient, and in fact problematic in terms of efficiency and reliability, to simply appropriate these

4 existing techniques and ideas to serve our purpose. 2.3 Safety-enhancing systems using pervasive technologies Wireless identification and sensor technologies can be used to enhance safety or alleviate the consequences of disasters, accidents, crimes, and so on, thereby increase people s sense of security. Certain schools experimented with GPS and RFID technologies so as to enhance school children s safety by tracking their whereabouts. Researchers and companies proposed to use RFID tags to classify disaster victims and track rescue supplies. Moreover, RFID tags embedded in the environment could facilitate communication and information sharing in critical rescue missions (Takizawa et al., 2004). Even though these ideas appear feasible from a technological perspective, they haven t been fully implemented in the real world. We can exploit visual, auditory and other types of information when searching victims, who could be under rubble, snow or soil. Wireless identification technologies such as avalanche beacons (H ller and Gibler, 2002) can facilitate such tasks despite their limitations in sensitivity, usability and battery life. Most existing wireless localization techniques don t fully consider the influence of various things that can exist around human bodies in abnormal situations. 2.4 Real-world deployments Positioning systems are increasingly incorporated into social systems to facilitate existing processes and practices (MIC, 2006). However, current incremental approaches are limited and inhibiting fundamental changes that can revolutionize the ways we do things. For example, some schools are making hand-drawn maps that show where kids hang out and pass by (NRIPS, 2006). Even though such a map can be a useful resource for designing preventive measures and acting in the right way during emergency situations, simply incorporating state-of-the-art GPS technology in this framework could lead to yet another low-accuracy map that has small impact on kids safety. Another example is the GPS-based location notification for cell phone emergency calls such as the Enhanced 911 (E911) in the United States and a similar system in Japan, which will be introduced in April Although such systems may allow police and rescue workers to locate victims more quickly than before, we believe the positioning accuracy in these systems is too low for time-critical rescue tasks that are characterized by Cara s Golden Hour Principle. E911 s positioning accuracy can be 50 to 300 meters (FCC, 2006) and the Japanese counterpart could provide the accuracy of 15 meters (MIC, 2006) under best conditions. However, accurately pinpointing a room in an apartment house, for example, requires much higher positioning accuracy. Our goal is to realize a seamless positioning infrastructure with the accuracy of 5 meters.

5 Interestingly, some local governments introduced low-tech location markers, namely human-readable printed numbers that is associated with corresponding location information. These numbers are displayed on vending machines and electric poles so that people, including tourists and foreign visitors, can simply communicate these numbers while making emergency calls. Introducing unobtrusive technologies such as RFID-based positioning systems in this space raises many open questions, most prominent being the ones related to the security and privacy issues in ubiquitous computing (Bellotti et al., 1993; Dourish and Anderson, 2006). Approaches to protecting consumers RFID privacy, such as the kill command, faraday cages, active jamming, and Blocker Tags (Juels et al., 2004) mainly concern with the Internet of Things setting where RFID tags are embedded in physical objects and we believe RFID tags embedded in physical spaces will define a set of unique security and privacy requirements that cannot be easily matched by existing solutions and proposals (EPCglobal 2005). 3 Approach In order to create RFID-based positioning systems for usable and useful safety-enhancing applications, we and our collaborators identified three key areas that require major breakthrough in research. Here we first outline general approaches in these areas and then the next section describes the software substrate, which is being developed in our group at the University of Tokyo. (1) Systems for seamless positioning and efficient location survey Our collaborators will develop economically feasible methods for embedding numerous RFID tags in physical spaces and linking them to location information (Matsuzaka et al., 2005). Additionally, they will develop novel location measurement equipment that captures location information from the embedded tags and establish standard land survey procedures using this equipment. (2) P2P-based positioning and communication We will develop mechanisms for the software substrate that exploits the embedded RFID location markers. We will develop privacy-preserving network protocols (Huang et al., 2005b) for exchanging location and environmental data, based on a P2P model. Using the protocols, mobile devices in proximity can mutually share their location and other contextual information to accurately estimate their positions even when they are away from RFID location markers. This mechanism can be extended so as to estimate and update RFID tags location information if it is unknown or imprecise. We will also develop a mechanism for location-based dissemination of emergency and disaster information that operates on the P2P-based software substrate. (3) Enhancing safety and sense of security using positioning systems Our collaborators will develop various methods for utilizing RFID-based positioning systems to enhance

6 safety and sense of security in everyday and emergency settings. First, people could exchange emergency and disaster information using embedded RFID tags as a reliable information storage device (Takizawa et al., 2004). Second, emergency phone calls made from indoor and underground spaces could utilize RFID location makers to reliably communicate relevant location information. Third, rescue workers could utilize RFID to know where they are and where the ones being rescued are (they could be buried under rubble, snow or soil.) Forth, adults could respond quickly and act proactively to enhance kids safety (NRIPS, 2006) if RFID-based positioning systems can provide the right kind of location-relevant information that serves the purpose. The provision of location information would be extremely beneficial in emergency and disaster context; however it also raises privacy issues. Our P2P-based technological architecture put RFID tags in physical places rather than people and therefore may provide users with more opportunities to control their privacy-sensitive information than existing systems. However, it s by no means a silver bullet and we must think seriously about the privacy implications of RFID-based positioning systems. Finally, research activities in the above three areas will be done in a collaborative fashion, and indeed they are closely related. We plan to integrate all research outcomes and demonstrate the advantages of our approach in a few years. 4 P2P-based positioning and communication In order to capture and exchange location information anywhere at any time, our system should be based on a network infrastructure that operates anywhere at any time. We believe that a P2P-based communication infrastructure would most closely approximate this goal. This type of infrastructure can operate even in areas where cell phones don t work and supports various hardware platforms besides mobile phones. Our approach builds on these strengths of a P2P-based network infrastructure and explores the following technical solutions for the relevant challenges in RFID-based positioning systems. 4.1 Privacy-preserving location disclosure Our P2P-based protocol for exchanging location information across mobile terminals is based on the addressing system called Spatio-Temporal Address (STA) (Yamazaki and Sezaki, 2004). When collocated mobile terminals exchange location information over an ad-hoc network, it is data-centric communication by nature and does not require the use of conventional machine addresses. In STA, terminals and devices are identified on the basis of their positions and time, which prevents detailed tracking of users activities across different locations and time. STA is suitable for building privacy-preserving mobile applications

7 since it doesn t permanently assign unique IDs (e.g., MAC addresses or IP addresses) on mobile terminals and devices. Moreover, we could develop gateways (or exploit IPv6 s multi-prefix function) to enable communications between STA-based devices and conventional IP-based devices. 4.2 User position estimation In our approach, users mobile devices communicate with each other so as to mutually refine their location information (c.f. Iterative Multilateration.) In general, mobile devices know their positions quite accurately right after they capture location information from nearby RFID location markers. However, the discrepancy between the captured location information and the devices actual positions increases when the devices move away from the location markers. We are developing techniques for carefully estimating the positions of mobile devices by considering their movement as well as the time stamps and the accuracy of captured location information. Our techniques are based on a P2P communication model that allows a group of nearby devices to exchange location-relevant information and collaboratively refine their knowledge about where they are. We can further improve the quality of location information by additionally using high-end mobile devices that are equipped with GPS receivers and sensors for detecting acceleration, magnetic fields, etc. Moreover, we can utilize geographical databases as well as contextual information such as users calendars to increase the accuracy of location information. 4.3 Position estimation for RFID location markers It is also a critical task to measure, record, and maintain each RFID marker s accurate location information. We will develop theories and models for estimating the positions of RFID location markers using the data captured by users mobile devices. Each mobile device can record an ID, time, estimated position, and its accuracy when it scans a nearby RFID location marker. The recorded information can be accumulated and analyzed to derive highly accurate position estimate. 4.4 Collecting and disseminating environmental information Our approach collects and disseminates information along with relevant location information, which allows us to route and index information based on locations. For example, data captured from distributed temperature sensors can be easily accumulated and indexed on a server to create meaningful visual map representations. Using STA, we could also develop a geocast mechanism (i.e., a multicast mechanism for the terminals in a certain geographic area) that selectively disseminates emergency or disaster information to people who are located in relevant geographical areas.

8 5 Conclusions and future works We described the context, challenges, and approaches of our research effort to design and build the software substrate for an envisioned national infrastructure that enables safety-enhancing services by embedding RFID location markers, developing novel positioning mechanisms, and providing key application services. The research described in this paper is still in an early stage and expected to soon produce outcomes that will greatly impact the decision making processes about a national RFID-based positioning infrastructure. Context awareness (Dourish and Moran, 2001) is an essential conceptual framework in ubiquitous networks that allows for delivery of the right information and services at the right place at the right time in the right way to the right people. Some context-aware systems automatically recognize users context and provide relevant services. In such systems, users location is one of the most important classes of contextual information. We think the market size of location-based services could grow exponentially if a truly ubiquitous and highly accurate positioning infrastructure is available. It could be best implemented as a national infrastructure based on collaborative efforts among relevant governmental sectors, especially when it can be a dual-use infrastructure that is also used to enhance safety and sense of security in certain situations. If the right RFID-based positioning infrastructure is implemented, it could be used to protect people from bodily injuries, loss of valuable assets, and so on in the cases of fire, flood, avalanches, landslides and other disasters and accidents. Moreover, parents are sometimes required to stand and watch school children along a school route in order to enhance safety of school children. This can be sometimes too burdensome for the parents. The right technological support may reduce some of the parents labors, still maintaining the state of safety along school routes. In addition, the same socio-technical infrastructure can be used to enhance safety of anyone including the elderly and the handicapped. Finally, as this research is part of a three-year project, our long-term interest includes the phase when our research outcomes potentially contribute to real-world systems and services after the completion of the project. We and our collaborators intend to initiate implementation-oriented projects for embedding and using RFID location markers as well as open forums to exchange relevant knowledge and an effort to standardize the key components of RFID-based positioning systems. Acknowledgments We would like to thank everyone in the project for useful comments and discussions. This research was supported by MEXT Special Coordination Funds for Promoting Science and Technology (No.13006), entitled RFID-based Positioning Systems for Enhancing Safety and Sense of Security

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