論文

For the success of a large deployment of UHF RFID, easyto-use and low-cost engineering tools to facilitate the performance evaluation are demanded particularly in installations and for trouble shooting. The measurement of interrogation area is one of the most typical industrial demands to establish the stable readability of UHF RFID. Exhaustive repetition of tag position change with a read operation and a usage of expensive measurement equipment or special interrogators are common practices to measure the interrogation area. In this paper, a practical method to measure the interrogation area of a UHF RFID by using a battery assisted passive tag (BAP) is presented. After introducing the fundamental design and performances of the BAP that we have developed, we introduce the measurement method. In the method, the target tag in the target installation is continuously traversed either manually or automatically while it is subjected to a repetitive read of a commercial interrogator. During the target tag traversal, the interrogator's commands are continuously monitored by a BAP. With an extensive analysis on interrogator commands, the BAP can differentiate between its own read timings and those of the target tag. The read timings of the target tag collected by the BAP are recorded synchronously with the target tag position, yielding a map of the interrogation area. The present method does not entail a measurement burden. It is also independent of the choice of interrogator and tag. The method is demonstrated in a practical UHF RFID installation to show that the method can measure a 40 mm resolution interrogation area measurement just by traversing the target tag at a slow walking speed, 300 mm/sec. Copyright © 2008 The Institute of Electronics, Information and Communication Engineers.

As RFID technology has been widely adopted, it has been acknowledged that user-specific data carrying RFID tags can be conveniently used. Since the typical user-specific data is sensor data, some existing studies have proposed new RFID architectures for sensor data handling. However, there are industrial demands to include non-sensor data, such as sales records, repair history, etc., as well as sensor data in the purview of our study. To realize handling of such general user-specific data, we need to satisfy requirements such as the minimum set of data semantics required to access the user-specific data, flexible user-specific data memory schema determination and partial collection of user-specific data. For this purpose, we designed the role of "session manager", which communicates with associate applications and notifies an interrogator what to do upon retrieval of a unique identification number. The session manager with the structured user-specific data can provide flexible collection and processing of user-specific data in the networked RFID. Since the fundamental drawback of the session manager might be the lookup overhead, we examined the overhead with a simulation based on experimental data. It was revealed that the overhead is equivalent to and in some cases even better than that of the existing method, which relies on structural tag memory. © 2008 Springer-Verlag Berlin Heidelberg.

In this paper, a network architecture for fast retrieval of user memory data of RF tag is proposed. The architecture features a network-based resolving of user memory layout in RF tag and an optimization of reading block according to application requests and the characteristics of interrogator. We implemented the proposed network architecture and evaluated the performance with commercial interrogator and commercial RF tags both of which are conformal to the fundamental specification of ISO/IEC 18000-6 Type C. The experimental and analytical evaluation reveals that the network-based memory resolving is effective particularly for interrogators which have large inventory overhead in a reading of user memory data. In our experiment, 3.3 times read speed up is achieved with the network-based resolving. The optimization of reading block is effective regardless of the protocol implementation of interrogator. We achieve 2.5 times speed up in the experiment in three sensor data reading from RF tag which has 2K bits memory. © 2013 IEEE.

This paper proposes a device discovery method for consolidated IP and ZigBee home networks. The method broadcasts an IP multicasted device discovery request of UPnP, m-search, in the ZigBee network as a Constrained Application Protocol (CoAP) message. Upon receiving the m-search broadcast, ZigBee devices respond after a constant time delay with their device description Universal Resource Name (URN). We refer to this device discovery mechanism as transparent msearch. Transparent m-search enables reliable and swift device discovery in home networks which may include constrained networks such as ZigBee. It is revealed by an experiment with 41 ZigBee devices that the delayed response from ZigBee devices is essential to avoid collisions between m-search broadcast and responses from devices and, as a result, to secure the reliability of device discovery. Since the transparent m-search requires the receiving ZigBee devices to respond with their device description URNs, the execution time of device discovery is significantly improved. In our experiment with 41 ZigBee devices, a conventional m-search took 38.1 second to complete device discovery while that of transparent m-search took only 6.3 second. © 2013 The Institute of Electronics, Information and Communication Engineers.