研究発表

Wireless sensors are expected to be low cost and to reduce their power consumption so that a large number of sensors can be installed for collecting real-world information. Passive radio-frequency identification (RFID) is proposed to assign communication channels to sensors that only send analog sensing signals for their multiple access control. In this method, the RFID reader-writer assigns channels to all sensors by writing channel numbers to the RFIDs attached to the sensors. We propose a method that more efficiently assigns a multiple access channel to the controlled sensor by using passive RFID. We determine the channel by using the electronic product code (EPC) of the RF tags. This approach results in a large reduction in the number of writes. However, it is shown that there is a tradeoff between the reduction in the number of writes and the total number of channels. In addition, our method has a tradeoff between the reduction in the number of writes and the spectral efficiency.

This paper proposes a plug-in type RF tag localization system, using an Angle of Arrival principle, in UHF RFID, particularly targeting handheld reader/writers. Being a plug-in type, the RF tag localization system is receive-only, incurring no radio license requirement, small in size and can be built at low cost. Our fundamental idea is to employ a newly developed short-range mono-pulse method for the RF tag direction detection enabled with affordable software defined radio device and an analog front end. In this paper, we report an experimental evaluation with a functional prototype primarily on the detecting accuracy. It is shown that we can achieve about 3 degree accuracy for RF tags at 7.3 m distance from a 4 W EIRP reader/writer. Because the measurement in the direction of boresight is more stable than the other directions, the direction accuracy can be improved when we feed back the direction detection to the orientation of handheld reader/writer. We also confirm this feature experimentally.

This paper introduces «Boxcan», an information retrieval platform for aggregated objects in ID-based object management system based on GS1 EPCglobal architecture framework. Boxcan platform receives an EPC of a container, then provides a tree structure of current parent-child relationship between the EPCs of the container and its inner objects. This paper proposes the system design of Boxcan platform and its applications. The proposed system design is evaluated with a field test of a practical object management system including Boxcan platform. A technical challenge to realize this function of Boxcan platform, fast retrieval of current parent-child relationship of EPCs from EPCIS, is also discussed in this paper. The effectiveness of the caching mechanism of EPC's current parent-child tree, which is a solution to this technical problem, is also evaluated by an experiment in a comparison with direct querying to EPCIS.

The authors have been working on a multi-subcarrier multiple access method which enables unsynchronized stream data collection from battery-less and wireless sensor nodes leveraging the passive backscattering technology. The multi-subcarrier multiple access can be realized just by controlling an RF switch which is implemented in commercial RFID tags. As the compensation of low-cost and simply circuitry size to realize a multiple access, there are mutual interference among subcarriers. But the interference can be canceled by an interference rejection signal processing in the receiver. In this paper, the performance limitation of the interference rejection is evaluated experimentally in various signal to noise ratio with a prototype multi-subcarrier multiple access system. The result shows that the interference rejection method is effective up to the desired signal to interfering noise ratio is as worse as -16dB.

During the past century, a whole new world has been created: the digital world. Along with the development of computers, internet, mobile devices, and etc, the digital world has created a whole new reality for human beings. Combined with new sensors, nowadays, everything that can be observed digitally is stored online and is being used for marketing and other uses. In this research, we aim to combine the world of digital and physical by using RFID (radio frequency identifier) and 3D printing technology. In detail, we embedded RFID modules inside 3D printed object, and wrote its information after the object was fully printed. With this, we aim to enhance the interaction between the real world and the virtual world, bringing more rich data transition and data manipulation.

This paper proposes a device and capability discovery protocol with integrated Universal Plug and Play (UPnP) and Object Naming Service (ONS). The protocol automatically establishes a list of available devices-sensors, actuators and electronic apparatus-in our home. Since each device is identified with a globally unique Electronic Product Code (EPC) in the protocol, the capability of discovered device can be obtained through ONS without implementing a complex capability description exchange protocol in the device. The up-to-dated list of all the available devices facilitates the compositions of smart home applications. This paper overviews the device and capability discovery protocol. Illustrative smart home applications in our campus enabled by the proposed protocol are also reported. © 2014 IEEE.

In this paper, we propose a cost effective and sustainable relief material visibility system. In an evacuation site such as the one prepared following a disastrous event such as the Tohoku earthquake, we have observed three issues on relief goods supply management: discrepancy between demands and supplies, difficulty of sorting and picking of relief material, and storage strategy to maintain optimal capacity and delivery time. To ease these issues, we developed a system which supports fulfillment by product category. Also, we implemented the system as an 'evacuee support mode' of a traceability system to share both software and hardware assets. By deploying as a dual-mode system, the system can be cost-effective and sustainable. We have developed a prototype system alongside with an agricultural ecommerce system with traceability support. We deployed the prototype at a disaster drill session to gauge the effectiveness of the design. © 2014 IEEE.