H. Vogt. Efficient Object Identification with Passive RFID Tags. In Pervasive 2002, pages 98--113, Zurich, Switzerland, August 2002.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....Philips I CODE system. The Philips I CODE system operates at a frequency of 13.56 MHz, i.e. it uses inductive coupling to transmit power and information between the RFID reader and the RFID tags, and it employs a stochastic anti collision protocol to detect multiple tags at once in its read range [7]. RFID tags in the form of flexible RFID labels, which are available in different sizes are attached to the physical objects in order to identify the smart objects. The unique 64 bit ID that is stored on the RFID tag is used as the ID to map between the physical objects and their virtual ....

H. Vogt. Efficient object identification with passive RFID tags. In F. Mattern and M. Naghshineh, editors, Proc. of the International Conference on Pervasive Computing, Pervasive2002.

....avoid timeconsuming collisions with other tags sending concurrently. The maximum number of time slots N which a tag may wait before answering, influences both the time needed for a single scan and the expected number of collisions. A small N value results in fast scans (down to 60ms according to [16]) but many collisions, whereas a large N value results in slow scans (more than one second) but few collisions. This kind of low level interface has several implications. First, applications are typically only interested in changes of the detected set of tags, i.e. they want to receive enter and ....

....can be achieved by selecting the number of time slots N to be slightly greater than the actual number M of tags in the range of the reader. However, M is typically unknown. Therefore, nontrivial algorithms are required for selecting N in order to read all present tags in a minimal amount of time [16]. History Some applications do not only react immediately to tagged objects entering and leaving the reading range, but objects are also queried about their history later on. Consider the Smart Tool Box example, where tools can be queried regarding how long they were used in which tool box on ....

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H. Vogt. Efficient Object Identification with Passive RFID Tags. In Pervasive 2002.

....in order to avoid time consuming collisions with other tags sending concurrently. The maximum number of time slots a tag may wait before answering influences both the time needed for a single scan and the expected number of collisions. A small value results in fast scans (down to 60ms according to [4]) but many collisions, whereas a large value results in slow scans (more than one second) but few collisions. This kind of low level interface has several implications. First, applications are typically only interested in changes of the detected set of tags, i.e. they want to receive enter and ....

....can be achieved by selecting the number of time slots to be slightly greater than the actual number of tags in the range of the antenna. However, is typically unknown. Therefore, nontrivial algorithms are required for selecting in order to read all present tags in a minimal amount of time [4]. Context Typically the application s action when a tag enters or leaves the antenna s range not only depends on the identity of the tag, but also on the presence or absence of other tags during this event which we call the context of the event. Consider for example the RFID Chef application: ....

H. Vogt. Efficient Object Identification with Passive RFID Tags. In Pervasive 2002.

.... While this seems a simple task at first, it is complicated by the fact that typically the RFID reader does not detect all present tags in each scan, an effect that is at least partially due to the anti collision algorithm, which enables the reader to distinguish and detect multiple tags at a time [10]. Even without changing the physical setting, the list of detected tags is typically changing with each scan. To handle this problem, the infrastructure should provide some means of event filtering, enabling the programmer to remove all leave events followed by an entry event for the same card ....

H. Vogt. Efficient Object Identification with Passive RFID Tags. In Pervasive 2002, pages 98--113, Zurich, Switzerland, August 2002.

....to avoid time consuming collisions with other tags sending concurrently. The maximum number of time slots # a tag may wait before answering influences both the time needed for a single scan and the expected number of collisions. A small # value results in fast scans (down to 60ms according to [17]) but many collisions, whereas a large # value results in slow scans (more than one second) but few collisions. The optimum performance can be achieved by selecting # to be slightly greater than the actual number # of tags in the range of the antenna. However, # is typically unknown. Therefore, ....

....store events to the VCES. Event Driver Using the RFID driver software , the ED periodically executes tag detection rounds. Each detection round consists of multiple tag scans with a carefully selected maximum time slots parameter # , which is obtained by using a mechanism we developed in [17]. The latter provides a technique for estimating the actual number of tags present from a scan result, which consists of a list of detected tags as well as the number and type of collisions. Thus, we start with a small value for # , estimate the number of tags # from the scan result, and ....

H. Vogt. Efficient Object Identification with Passive RFID Tags. Submitted for publication, February 2002. www.inf.ethz.ch/vs/publ/papers/rfid obj.pdf.

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H. Vogt. Efficient Object Identification with Passive RFID Tags. In Pervasive 2002, pages 98--113, Zurich, Switzerland, August 2002.

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Harald Vogt. Efficient object identification with passive RFID tags. In F. Mattern and M. Naghshineh, editors, International Conference on Pervasive Computing, volume 2414 of Lecture Notes in Computer Science, pages 98--113, Zurich, August 2002. Springer-Verlag.

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