In this paper we present a novel active radio frequency identification system consisting of transponders with low complexity, low power consumption, and long system reading range. The transponder’s low complexity and small circuit integration area indicate that the production cost is comparable to the one of a passive tag. The hardware keystone is the transponder’s radio wake-up transceiver, which is a single oscillator with very low power consumption. The communication protocol, based on frequency signalling binary tree, contributes to the low complexity of the tag architecture. More than 1500 tags can be read per second. The average transponder ID read-out delay is 319 ms when there are 1000 transponders within reach of the interrogator. The calculated expected life time for a transponder is estimated to be almost three years.

In this paper we describe and evaluate anenhanced version of an active RFID wake-up and tag IDextraction radio communication protocol. The enhancedprotocol further reduces the transponders’ power consumption(prolonging their battery lifetime). The protocol uses afrequency binary tree method for extracting the identificationnumber of each transponder. This protocol is enhanced byextending it with a framed slotted medium access controlmethod which decreases the number of activations of eachtransponder during tag ID extractions. Using this medium accessmethod, the average number of transponder activations isdecreased with a factor of 2.5 compared to the original protocol.The resulting increase in ID read-out delay is 0.9%, on average.

In this paper we present a Radio Frequency Identification (RFID) protocol used to wake up and extract the ID of every tag (or a subset thereof) within reach of a reader in an active backscatter RFID system. We also study the effect on tag energy cost and read-out delay incurred when using the protocol, which is based on a frequency binary tree. Simulations show that, when using the 2.45 GHz ISM band, more than 1500 tags can be read per second.With a population of 1000 tags, the average read-out delay is 319 ms, and the expected lifetime of the RFID tags is estimated to be more than 2.5 years, even in a scenario when they are read out very often.

The communication protocol used is a key issue in order to make the most of the advantages of active RFID technologies. In this paper we introduce a carrier sense medium access data communication protocol that dynamically adjusts its back-off algorithm to best suit the actual application at hand. Based on a simulation study of the effect on tag energy cost, read-out delay, and message throughput incurred by some typical back-off algorithms in a CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) active RFID protocol, we conclude that by dynamic tuning of the initial contention window size and back-off interval coefficient, tag energy consumption and read-out delay can be significantly lowered. We show that it is possible to decrease the energy consumption per tag payload delivery with more than 10 times, resulting in a 50% increase in tag battery lifetime. We also discuss the advantage of being able to predict the number of tags present at the RFID-reader as well as ways of doing it.

Active Radio Frequency Identification (A-RFID) is a technology where the tags (transponders) carry an on-board energy source for powering the radio, processor circuits, and sensors. Besides offering longer working distance between RFID reader and tag than passive RFID, this also enables the tags to do sensor measurements, calculations and storage even when no RFID-reader is in the vicinity of the tags. In this paper we introduce a medium access data communication protocol which dynamically adjusts its back-off algorithm to best suit the actual active RFID application at hand. Based on a simulation study of the effect on tag energy cost, readout delay, and message throughput incurred by some typical back-off algorithms in a CSMA/CA (Carrier Sense Multiple Access / Collision Avoidance) A-RFID protocol, we conclude that, by dynamic tuning of the initial contention window size and back-off interval coefficient, tag energy consumption and read-out delay can be significantly lowered. We also present specific guidelines on how parameters should be selected under various application constraints (viz. maximum readout delay; and the number of tags passing).

This paper presents an investigation into using a combination of two alternative digital number representations; the residue number system (RNS) and the signed-digit (SD) number representation in digital arithmetic circuits. The combined number system is called RNS/SD for short. Since the performance of RNS/SD arithmetic circuits depends on the choice of the moduli set (a set of pairwise prime numbers), the purpose of this work is to compare RNS/SD number systems based on different sets. Five specific moduli sets of different lengths are selected. Moduli-set-specific forward and reverse RNS/SD converters are introduced for each of these sets. A generic conversion technique for moduli sets consisting of any number of elements is also presented. Finite impulse response (FIR) filters are used as reference designs in order to evaluate the performance of RNS/SD processing. The designs are evaluated with respect to delay and circuit area in a commercial 0.13 μm CMOS process. For the case of FIR filters it is shown that generic moduli sets with five or six moduli results in designs with the best area × delay products.

Active radio frequency identification (A-RFID) is a technology where the tags (transponders) carry an on board energy source for powering the radio, processor circuits, and sensors. Besides offering longer working distance between RFID-reader and tag than passive RFID, this also enables the tags to do sensor measurements, calculations and storage even when no RFID-reader is in the vicinity of the tags. In this paper we study the effect on tag energy cost and read out delay incurred by some typical back-off algorithms (constant, linear, and exponential) used in a contention based CSMA/CA (carrier sense multiple access/collision avoidance) protocol for A-RFID communication.

The use of Radio Frequency Identification systems (RFID) is growing rapidly. Today, mostly “passive” RFID systems are used because no onboard energy source is needed on the transponders. However, “active” RFID technology, with onboard power sources in the transponders, gives a range of opportunities not possible with passive systems. To obtain energy efficiency in an Active RFID system the protocol to be used should be carefully designed with energy optimization in mind. This paper describes how energy consumption can be calculated, to be used in protocol definition, and how evaluation of protocol in this respect can be made. The performance of such a new protocol, in terms of energy efficiency, aggregated throughput, delay, and number of air collisions is evaluated and compared to an existing, commercially available protocol for Active RFID, as well as to the IEEE standard 802.15.4 (used e.g. in the Zigbee mediumaccess layer).

Active Radio Frequency Identification (A-RFID) extends the functionality from the predecessor passive RFID trough adding a power source to the transponder device (device used on a product to identify it). This power source enables more advanced functions in the radio interface such as listening (doing a carrier sense) to the radio channel (carrier of data information) finding out if it is unengaged, and free to use. In this paper we study the carrier sense functionality and its effects in lowering the tag energy consumption. Simulation results show that the life time of a tag, in an A-RFID system, using carrier sense is more than doubled compared to one not using carrier sense. The increased lifetime of the tag is due to the lowered energy consumption caused by the improved throughput and the decreased payload delay, which in turn is thanks to using carrier sense and naturally then give a better utilization of the radio channel.