US20060103533A1 - Radio frequency tag and reader with asymmetric communication bandwidth - Google Patents

Radio frequency tag and reader with asymmetric communication bandwidth Download PDF

Info

Publication number
US20060103533A1
US20060103533A1 US10988271 US98827104A US2006103533A1 US 20060103533 A1 US20060103533 A1 US 20060103533A1 US 10988271 US10988271 US 10988271 US 98827104 A US98827104 A US 98827104A US 2006103533 A1 US2006103533 A1 US 2006103533A1
Authority
US
Grant status
Application
Patent type
Prior art keywords
tags
tag
reader
readers
system
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US10988271
Inventor
Kourosh Pahlavan
Farokh Hassanzadeh Eskafi
Original Assignee
Kourosh Pahlavan
Farokh Hassanzadeh Eskafi
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Images

Classifications

    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06KRECOGNITION OF DATA; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0008General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06KRECOGNITION OF DATA; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10009Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
    • G06K7/10297Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092
    • G06K7/10306Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092 ultra wide band

Abstract

A method and apparatus to overcome fundamental shortcomings in narrow band as well as wide band RFID solutions through offering a hybrid solution that utilizes benefits of narrow band in the downlink direction with the benefits of ultra wide band in the uplink. The invention encompasses a multitude of methods, including an approach to increase the ability to capture electromagnetic energy from the reader.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • 3,516,575 Muffitt et al. June 1967
    3,199,424 Vinding, J. January 1967
    3,541,995 Fathauer, H. George November 1968
    3,689,885 Kaplan et al. September 1972
    3,713,148 Carelullo et al. January 1973
    6,550,674 Neumark, Yoram April 2003
  • STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
  • N/A
  • BACKGROUND OF THE INVENTION
  • This invention relates generally to object and inventory identification and control systems and more particularly to a system using inventory identity labels mounted adjacent to inventory items. These labels provide identification information relative to the inventory, wherein the labels are enabled for communication with a computerized inventory management system, and wherein the labels' location and status is known at any time from a remote location.
  • Radio Frequency Identification (RFID) refers to utilization of RF signals as means of communication between responders, normally tags or similar modules, and interrogators, normally called readers. See e.g. U.S. Pat. Nos. 3,299,424 and 3,689,885.
  • The simplest RFID tags comprise an ID, normally in a digital binary form, that is modulated on an RF carrier signal propagated by the tag as described in e.g. U.S. Pat. No. 3,713,148.
  • Radio communication between a tag and a reader can be done in two principally different ways. One way is using a tuned circuitry in the tag such that when exposed to the electromagnetic field generated by the reader, the tag comes into oscillation and interacts with the reader field. The tag can use the effect of this self-oscillation, which manifests itself as an inhibition of the original field generated by the reader to present its ID or data. This self-oscillation can be used to connect the reader and the tag by means of magnetic coupling or backscattering. Under these circumstances the reader can sense the presence of the tag and demodulate the data that the tag has modulated into the field inhibition pattern caused by magnetic coupling or backscattering by the tag; see e.g. U.S. Pat. Nos. 3,516,575 and 3,541,995.
  • The second approach is to have a set-up like the one in normal RF communication, i.e. the readers transmit signals that are received by the tags and the tags transmit signals that can be detected and decoded by the readers. In this approach, the structure of the signal transmitted by the tag is inherently independent of the signal received by it. Thereby, the tag can, e.g. receive information from the reader in one band and transmit it in a completely unrelated band and with a different signal structure and technology.
  • There are variations of the first approach that use backscattering in a band that is an integer multiple or fraction of the original received signal, but this flexibility is limited to this frequency multiplication/division only. There are also other approaches using Surface Acoustic Wave, Acoustomagnetic and electrical coupling as means of responding to the reader. However, these approaches can all be classified in the same category of devices that generate a reaction to the original field created by the reader and inhibit the same through this reaction.
  • In the first approach, the tag can be a completely passive element in that it does not require any source of power to inhibit the electromagnetic field created by the reader and thereby convey its data. The tag responds by presenting its ID or other data through the inhibition pattern that is in turn sensed by the reader monitoring its own transmitted signal.
  • In the second approach, transmitting the data back to the reader requires power like any other RF transmission.
  • Regardless of the approach, the logic engine of the tag that processes and transports the stored ID or data still needs power.
  • This power can be provided by a source of energy that is integrated with the tag, e.g. a battery or an accumulator of some kind. But it can also be generated by other means, e.g. by capturing the electromagnetic energy propagated by the reader or similar sources of emitting such signals. This process requires a circuitry that can convert electromagnetic energy to such current and voltage levels that can satisfy the power needs of the tag circuitry. A tag in the first approach will not need this recovered data for its transmission stage, because it transmits as a reaction to the field that is exciting it. In the second approach, a tag can however use this electrical energy to power up its transmission stage and transmit its data back to the reader or other units prepared to communicate with it.
  • Magnetic coupling works only at very short distances and backscattering relies on small signal reflections that only offer a limited range and a low bandwidth for data exchange between the tag and the reader. However, tags made with this approach are simple and cheap to manufacture, because their transmission stages are passive and their active control and data processing stages are simple and low power so that, at least at short range, they can supply their needed power by capturing electromagnetic energy through simple and affordable power rectification circuitry on the tag.
  • Using a RF transmission stage, in accordance with the second approach, offers more flexibility, longer range and higher data rate at higher complexity and power consumption due to the complexity of the baseband and addition of an independent transmission stage. Therefore, such tags are quite often battery powered active tags. Active RF tags tend to be larger in size and more expensive than corresponding passive ones.
  • Regardless of whether the tag acts as an active transmitter or backscatters passively, all the communication between a tag and a reader is performed in certain regulated frequency bands. The amount of output power in each band is regulated to ensure the integrity of the neighboring spectrum against signal pollution. These bands are normally narrow bands in LF, HF, UHF and Microwave portions of the RF spectrum.
  • Generally, there are a number of problems associated to currently available narrowband RFID technologies. These are:
      • Low data rate and lack of noise immunity, limiting an item-level tagging and high simultaneous number of interrogations by the reader.
      • The tags are nearly useless on metal or such containers that contain conductive material, dielectric liquids and in general such material that can cause detuning of the signal through reflection and absorption.
      • Any attempt to remedy the above problems or additional functionality results in a complexity in the circuitry that opposes the cost and power constraints.
  • These issues are mostly addressed by deploying Ultra Wide Band (UWB) radio. Recent attention to UWB radio and its application to RFID have brought about new possibilities in terms of higher data rate, lower power consumption, location determination, resilience to multi-path distortion and media penetration and reflection.
  • UWB or Impulse Radio is a carrier-less radio whose signal is in simple terms only an extremely short pulse in the time domain. This very short pulse in the time domain corresponds to an extremely wide bandwidth in the frequency domain.
  • Due to its impulse nature, the transmitter stage in the UWB radio is very simple. The requirements of the UWB receiver stage on filters, amplifiers and detection circuits that can handle the extremely wide bandwidth, among other factors, make its design more challenging. In comparison, a narrow band radio can be more challenging in the transmitter stage and less challenging in the constraints imposed on the amplification and detection stages of the receiver.
  • UWB radio is extremely low power while it offers a very high data rate. Due to its very wide frequency content, impulses can penetrate material with an unprecedented performance and they are very resilient to multi-path limitations imposed on narrowband radio. These qualities have made UWB a natural choice for high performance Radars and mine detectors.
  • Narrow band RFID techniques are invented and utilized across a broad range of applications. UWB radio communication is also applied to RFID in several embodiments for different applications; see e.g. U.S. Pat. No. 6,550,674. The embodiments are normally larger tags that deploy internal batteries and complex transceivers.
  • A BRIEF SUMMARY OF THE INVENTION
  • It is an objective of the present invention to provide a solution to the shortcomings of the currently available RFID designs by combining narrowband and Ultra Wide Band technologies. The system, methods and apparatuses provided by the present invention alleviates these shortcomings by exploiting the benefits of narrow and wide band communication between tags (responders) and readers (interrogators). Using a narrowband link from the reader to the tag warrants for the ability to transmit powerful signals that can in the frame of allowed power envelopes set by regulatory authorities energize passive tags in a way that their internal circuitry can be powered up wholly or partially by the received signals. Conversely, using an Ultra Wide Band link from the tag to the user warrants for high data rate, low power, massive simultaneous communications between the tags and the readers that are resilient to multipath, penetration and reflection problems that the currently available narrow band RFID technologies suffer from.
  • It is another objective of this invention to alleviate the problems that currently available UWB technologies suffer from. A regular UWB radio transmits low power signals over a very wide band. Transmitting high power over such a broad band would pollute the RF spectrum and interfere with other wireless devices in those bands. Furthermore, the UWB transmitter is extremely simple to design, whereas the receiver stage could be more complex and power consuming. Conversely a narrowband receiver is low power and simple. By using UWB as means of transmitting data from the tag to the reader only, all the benefits of UWB and all the benefits of narrow band can be achieved simultaneously.
  • It is yet another objective of this invention to enable design of an RFID tag that deploys separate transmitter and receiver stages, whereby the transmitter function can be completely decoupled from the limitations that the receiver design can impose on the transmitter. The ability to combine narrow band and UWB radios on receiver and transmitter stages respectively is a lucid example of benefits from such decoupling.
  • It is yet another objective of this invention to create tags and readers that are according to the said asymmetric bandwidth also maintains backward compatibility with legacy RFID systems; see FIG. 3.
  • It is yet another objective of this invention to provide yet another technique to transmit more power to an RFID tag by deploying multiple tuned circuits in the front-end of the tag so as to capture energy from different bands simultaneously; see FIG. 5.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 illustrates the direction of communication and the radio technology of the transmitter and receiver units in a tag and a reader respectively. It also elucidates the directions called “uplink” and “downlink”.
  • FIG. 2 is the block diagram of the main components of a responder or tag in one embodiment of the invention.
  • FIG. 3 is the block diagram of another embodiment of the invention. In this embodiment, the tag and the reader are designed such that they can function in a legacy network as well as the network of responders (tags) and interrogators (readers) as described by this invention.
  • FIG. 4 explains the direction of the signals and the continuous overlapping nature of the energizing signal with respect to the data exchange between the tags and a reader that is capable of multiple simultaneous narrow band radio transmissions. Signals on different channels or bands can energize the same tag simultaneously and thereby enhance its ability to gain electrical energy. The capability of the tags to listen to and to be energized by the reader signals in different bands can also enhance location determination, multi-access techniques, bit-rate and the overall system performance.
  • FIG. 5 depicts an embodiment of the front-end of a multi-band energizing design in a tag.
  • FIG. 6 depicts the high-level architecture of an RFID network as suggested by one embodiment of this invention.
  • DETAILED DESCRIPTION OF THE INVENTION
  • As illustrated in FIG. 1, the invented reader uses narrow band channels to interrogate the tag. This direction of communication is called a downlink communication. The used band can be in any portion of the spectrum where radio communication is possible. The receivers of these narrowband signals, i.e. the tags, transmit their responses back to the readers in a stream of UWB impulses. The direction of communication in this case is called uplink (see FIG. 1). This means that each reader uses at least a narrowband transmitter and a UWB receiver, while each tag utilizes a UWB transmitter and a narrowband receiver. This asymmetric utilization of the bandwidth, which is the core of this invention, has many benefits, among them:
      • A UWB transmitter is very simple, low power, easy to design and cheap. This is true for a narrowband receiver as well. By deploying these two simplest combinations of the UWB and narrowband technologies, the tag which is the most critical element of an RFID network, will end up having a simple and cheap solution.
      • The Ultra Wide Band transmitter offers nearly all the benefits of a UWB radio in an RFID network. It offers an RFID tag that is resilient to multipath, penetration and reflection problems that narrowband RFID tags normally suffer from. Furthermore, UWB provides an RFID system with unique capabilities in terms of location determination that are not offered by narrowband radio. The narrowband receiver of the tag can be tuned to listen to a very narrow channel, which in turn can enhance detection ability. The virtue of having a narrow band receiver in the tag also enables the reader to exploit the maximum allowable power output in the allowed band without interfering with other radio systems. Thereby the reader can provide enough signal strength to power up the tag through its narrow band receiver. A reader with a UWB transmitter would not be able to output enough RF energy to power up the tag, without polluting its utilized spectrum.
      • Since the transmitter stage of the tag is a very low power UWB radio and its receiver stage can provide it with more power through the strong incoming narrow band signals, a tag that can be completely passive and still offer long range, high bandwidth location determination and immunity to reflection, multipath and penetration can be realized.
  • Magnetically coupled or backscattering RFID tags can also use an embedded source of power to assist their digital circuitry when enough power is not recycled from the reader signal. However, this internal source of power—normally a battery—cannot easily participate in the process of radio transmission, because the transmitted signals are reflections or inhibitions of the original reader signal. Deploying a stand-alone transmitter stage, as is the case with the present invention, entails a capability to use the internal or external power in any way needed. In this particular case, it can be used to increase the power output of the transmitter to achieve a longer range and better signal quality.
  • A reader signal is normally a carrier on which the reader command and data are modulated. This carrier signal also provides the power for the tag. The signal from the reader to the tag can be continuous or sequentially pulsed, depending on the way the tags need to be powered up, the number of the tags, and the multi-access method used for simultaneous access of multiple tags. If the network deploys a TDMA (Time Division Multiple Access) scheme, the tags will respond sequentially in accordance with the timing protocol. However, the duration and the band in which the signal is transmitted by the reader can cause different tags or subnets of tags to be powered up and respond, simultaneously or sequentially. FIG. 4 illustrates another embodiment of the invention in which case the carrier signal is continuously broadcast over all tags in the network in channel P, while the same reader also transmits a narrow band signal in band Q, but only for a specific subnet of tags, which can, e.g. need the extra power because of being far from the reader. In this embodiment, the tag is equipped with additional circuitry that allows the tag to capture electromagnetic power from different bands of the spectrum. FIG. 5 illustrates this detail in the “Power Recovery, Supply and Generation” module depicted in FIG. 2.
  • The multi-band energizing scheme can be used as a multi-access facilitator, but it can also provide increased bit-rate from the reader to the tags, enhance location determination, and in general increase the system performance.
  • In one embodiment of the present invention, the narrowband receiver of the tag can behave like a legacy RFID tag, e.g. perform magnetic coupling or backscattering. In this embodiment, the tag will have the additional circuitry to create the return signal in accordance with the technology in use (e.g. inductive coupling, backscattering, etc.) and modulate its ID and data on this returned signal. FIG. 3 illustrates this embodiment in the case of using magnetic coupling. As depicted in the figure, a reader that is an embodiment of this invention with said backward compatibility can communicate with legacy tags as well as those in accordance with this invention. Furthermore, tags of this invention that comply with this said backward compatibility can communicate with legacy readers and systems.
  • A typical network architecture for different embodiments of this invention is illustrated in FIG. 6. A multitude of readers can be present in a network, each serving a number of tags that may be members of different subnets of different readers simultaneously. These tags could be passive, active or legacy tags that do not comply with the technology described in this invention, but still accessible to the readers, because of the backward compatibility of the readers to the legacy RFID tags.
  • Readers communicate with the tags wirelessly. However, they can communicate with each other through a wired or wireless communication. This flexibility in connection is also true about the communication between readers and local servers and gateways. The readers and other elements of the network such as local servers, gateways, databases, and storage units can share or create a Local Area Network (LAN) that can internally be interconnected with wires or wirelessly. Finally, the network can connect to external networks and the Internet through its gateways or other computers in the LAN that are capable of external communication.
  • FIG. 6 illustrates the high-level architecture of the system that is an embodiment of this invention. At the lowest level of the hierarchy, there are a considerable number of items with active and passive tags mounted on them. The presence of a UWB transmitter stage in the tags warrants for the system's capability to reach a massive item-level deployment; the high data rate and thereby a large system capacity allows for mass interrogations in short time intervals.
  • Due to their very simple design, the passive tags are very low cost. They are composed of a very small CMOS chip mounted on a substrate that carries the narrow band antenna (or a wound loop) for the receiver and the UWB antenna for the transmitter.
  • An active tag has an integrated battery. This battery could be in similar embodiments substituted by a rechargeable accumulator or a capacitor. The active tag exploits the reader signal in the extent it can. When the distance to the reader is too far for the passive solution to overcome, the battery power is switched on to boost performance. Such a tag is often called a semi-active tag.
  • The active tag can also solely rely on its battery resource; thereby it does not need to be a continuous slave of one particular reader and can initiate communication sessions and scheduled processings on its own.
  • The second element of the system in the hierarchy is the reader. The reader is designed so as to be backward compatible with the traditional narrow band RFID systems as well as UWB tags (see FIG. 3). Thereby, it can function across different standards and solutions. However, the basic function of the reader in this system will be to fulfill the subject of this invention, i.e. communicate with the tags over a narrow band channel in downlink and UWB in uplink. The reader is a node in a larger network of readers that can be scattered over a local or wide area network.
  • The network of readers is intertwined and integrated with the network of the third element of the system, i.e. the server node. The server nodes are local control, communication and management units of the system. However, they can work as gateways to other networks or subsystems of tags and readers or other computational and communication units, e.g. enterprise servers and databases.
  • FIG. 2 depicts the internal architecture of the passive tag in this embodiment. Upon a session initiation, the reader broadcasts a signal that powers up all the tags in its reach. The receiver front-end of the passive tags is divided into three parallel sections. These are:
      • Power Recovery & Supply Generation: a section for capturing electromagnetic energy and converting it to useful current and voltage levels.
      • Clock Recovery: a section that has the task of creating a system clock for different blocks on the chip. This clock also provides the basic building block for the UWB impulse generation circuitry.
      • Receiver: a section that detects and extracts the data and commands modulated on the incoming signal.
  • The main processing unit onboard takes care of baseband processing as well as control and system management of the entire chip. The code for this work as well as encryption, decryption and identification codes are stored in any non-volatile memory compatible with the processing used for the rest of the tag chip (e.g. CMOS, BiCMOS, etc.). This memory can be mask ROM, PROM, EPROM, EEPRM, Flash, FeRAM, MRAM, etc. depending on the custom needs and cost constraints. The working memory of the processor is a RAM block.

Claims (9)

  1. 1. A system with a multitude of radio transceivers called readers and a multitude of radio transceivers called tags, wherein the readers transmit radio frequency signals to the said tags in a narrow frequency band and receive radio frequency signals from the said tags in an ultra wide frequency band. Conversely, the said tags transmit in narrow band and receive in ultra wide band.
  2. 2. A system as in 1 where each individual tag maintains the capability to store, erase, update and process local and incoming data.
  3. 3. A system as in 1 and 2, where the signal energy transmitted from the reader in narrow band also electrically and remotely energizes the circuitry in the tags individually or collectively over the air to wholly or partially substitute battery or other sources of power in the tag.
  4. 4. A system as in 1 to 3, where the relationship between tag and reader is reversed, i.e. the tag transmits in narrow band and receives in ultra wide band, while the reader transmits in ultra wide band and receives in narrow band.
  5. 5. A system as in 1 to 4 whereas the network of the multitude of tags and readers can be organized and supervised by a multitude of central or distributed servers that can control, process and store the information flowing in the network of tags and readers.
  6. 6. A system such as in 1 to 5 where readers and tags are both capable of using ultra wide band radio for both transmission and reception of data, while the tags are still powered by narrowband signals from the readers.
  7. 7. A system as in 1 to 6 where individual tags and readers can listen to other propagating units, including other tags and readers in order to organize their activity in the total network.
  8. 8. An RFID system that utilizes several circuits each tuned for different frequencies in the receiving front-end so as to enable the tag to simultaneously capture electromagnetic energy in the said frequencies.
  9. 9. A system such as in 1-8 where the narrowband receivers and the narrowband transmitters are completed with such functionality to enable them to be compatible with legacy narrowband methods and devices.
US10988271 2004-11-15 2004-11-15 Radio frequency tag and reader with asymmetric communication bandwidth Abandoned US20060103533A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US10988271 US20060103533A1 (en) 2004-11-15 2004-11-15 Radio frequency tag and reader with asymmetric communication bandwidth

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US10988271 US20060103533A1 (en) 2004-11-15 2004-11-15 Radio frequency tag and reader with asymmetric communication bandwidth
US11270922 US7180421B2 (en) 2004-11-15 2005-11-12 Radio frequency tag and reader with asymmetric communication bandwidth
JP2007541366A JP4934050B2 (en) 2004-11-15 2005-11-14 Radio frequency tag and a reader according to an asymmetrical communications bandwidth
CN 200580046302 CN101160608B (en) 2004-11-15 2005-11-14 Radio frequency tag and reader with asymmetric communication bandwidth
EP20050825927 EP1812909B1 (en) 2004-11-15 2005-11-14 Radio frequency tag and reader with asymmetric communication bandwidth
PCT/US2005/040977 WO2006055431A3 (en) 2004-11-15 2005-11-14 Radio frequency tag and reader with asymmetric communication bandwidth

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US11270922 Continuation-In-Part US7180421B2 (en) 2004-11-15 2005-11-12 Radio frequency tag and reader with asymmetric communication bandwidth

Publications (1)

Publication Number Publication Date
US20060103533A1 true true US20060103533A1 (en) 2006-05-18

Family

ID=36385709

Family Applications (2)

Application Number Title Priority Date Filing Date
US10988271 Abandoned US20060103533A1 (en) 2004-11-15 2004-11-15 Radio frequency tag and reader with asymmetric communication bandwidth
US11270922 Expired - Fee Related US7180421B2 (en) 2004-11-15 2005-11-12 Radio frequency tag and reader with asymmetric communication bandwidth

Family Applications After (1)

Application Number Title Priority Date Filing Date
US11270922 Expired - Fee Related US7180421B2 (en) 2004-11-15 2005-11-12 Radio frequency tag and reader with asymmetric communication bandwidth

Country Status (3)

Country Link
US (2) US20060103533A1 (en)
JP (1) JP4934050B2 (en)
CN (1) CN101160608B (en)

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050151991A1 (en) * 2003-12-26 2005-07-14 Naoto Shiraishi Image processing apparatus, image processing method, and computer product
US20060164206A1 (en) * 2005-01-27 2006-07-27 Buckingham Duane W Reduced power electronic lock system
US20070063013A1 (en) * 2005-09-19 2007-03-22 Lexmark International, Inc. Systems and methods for maintaining warranty claim information
US20070249314A1 (en) * 2004-03-19 2007-10-25 Sirit Technologies Inc. Adjusting parameters associated with transmitter leakage
US20080151313A1 (en) * 2006-12-21 2008-06-26 Konica Minolta Business Technologies, Inc. Image monitoring system for preventing confidential information outflow, image monitoring method, and computer image monitoring program stored on a computer readable medium
US20080272889A1 (en) * 2005-01-19 2008-11-06 Innovision Research & Technology Plc Nfc Communicators and Nfc Communications Enabled Devices
US20090015371A1 (en) * 2007-07-10 2009-01-15 Xavier Bocquet System and method of controlling access to services
US20090267746A1 (en) * 2008-04-23 2009-10-29 Martec Corporation Multi-Port Receiver
US20090284354A1 (en) * 2008-05-19 2009-11-19 Sirit Technologies Inc. Multiplexing Radio Frequency Signals
US20100107985A1 (en) * 2007-03-22 2010-05-06 Faire (Ni)Limited Animal monitoring system and method
US20100176921A1 (en) * 2009-01-09 2010-07-15 Sirit Technologies Inc. Determining speeds of radio frequency tags
US20100277286A1 (en) * 2009-05-01 2010-11-04 Burkart Scott M Synchronization of devices in a RFID communications environment
US20100277284A1 (en) * 2009-05-01 2010-11-04 Brown Jonathan E Data separation in high density environments
US20100277280A1 (en) * 2009-05-01 2010-11-04 Burkart Scott M Systems and methods for relaying information with RFID tags
US20100277283A1 (en) * 2009-05-01 2010-11-04 Burkart Scott M Systems and methods for RFID tag operation
US20100289623A1 (en) * 2009-05-13 2010-11-18 Roesner Bruce B Interrogating radio frequency identification (rfid) tags
US20100302012A1 (en) * 2009-06-02 2010-12-02 Sirit Technologies Inc. Switching radio frequency identification (rfid) tags
US20100328043A1 (en) * 2008-02-29 2010-12-30 Nokia Corporation Interrogation of rfid communication units
US20110159817A1 (en) * 2009-12-29 2011-06-30 Pirelli Tyre S.P.A. Method and system for managing communications between sensor devices included in a tyre and a sensor coordinator device
US20110205025A1 (en) * 2010-02-23 2011-08-25 Sirit Technologies Inc. Converting between different radio frequencies
US20110298619A1 (en) * 2008-12-11 2011-12-08 Faire (Ni) Limited Animal monitoring system and method
US20120134389A1 (en) * 2010-11-29 2012-05-31 Tagarray, Inc. Passive wireless connection
US8226003B2 (en) 2006-04-27 2012-07-24 Sirit Inc. Adjusting parameters associated with leakage signals
US8248212B2 (en) 2007-05-24 2012-08-21 Sirit Inc. Pipelining processes in a RF reader
US8427316B2 (en) 2008-03-20 2013-04-23 3M Innovative Properties Company Detecting tampered with radio frequency identification tags
CN103854469A (en) * 2012-11-28 2014-06-11 苏州工业园区新宏博通讯科技有限公司 Collector
WO2016106194A1 (en) * 2014-12-22 2016-06-30 Datalogic IP Tech, S.r.l. Ultra-wideband location engine for self-shopping devices
US10062025B2 (en) 2012-03-09 2018-08-28 Neology, Inc. Switchable RFID tag

Families Citing this family (85)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8045935B2 (en) * 2001-12-06 2011-10-25 Pulse-Link, Inc. High data rate transmitter and receiver
FR2851860B1 (en) * 2003-02-28 2005-04-15 Suisse Electronique Microtech Method for mitigation of the influence of interference produced by burst radio transmission systems in communications uwb
JP4370597B2 (en) * 2003-09-11 2009-11-25 マレーシア国 ic chip and, reading method of the data for identification, the writing method
JP4317431B2 (en) * 2003-12-03 2009-08-19 マレーシア国 And ic chip for identification, reading method of the data
US7342490B2 (en) * 2004-11-23 2008-03-11 Alien Technology Corporation Radio frequency identification static discharge protection
US20060109084A1 (en) * 2004-11-24 2006-05-25 Mark Yarvis Mesh networking with RFID communications
US20060151615A1 (en) * 2005-01-12 2006-07-13 Taiwan Name Plate Co., Ltd. Radio identifiable mark
US20060238304A1 (en) * 2005-04-21 2006-10-26 Sean Loving System and method for adapting an FRID tag reader to its environment
US7970345B2 (en) * 2005-06-22 2011-06-28 Atc Technologies, Llc Systems and methods of waveform and/or information splitting for wireless transmission of information to one or more radioterminals over a plurality of transmission paths and/or system elements
EP1788722A1 (en) * 2005-11-21 2007-05-23 Nortel Networks Limited Transmission method and related base station
US8269629B2 (en) * 2005-11-21 2012-09-18 Hewlett-Packard Development Company, L.P. Method and system for item tracking with tags
US7817044B2 (en) * 2005-11-30 2010-10-19 Intel Corporation RFID enabled multiband antenna
DE102005057546B4 (en) * 2005-12-01 2007-08-16 Kathrein-Austria Ges.M.B.H. Method and device for contactless transmission of data from a plurality of data carriers, preferably in the form of RFID tags
WO2007083355A1 (en) * 2006-01-17 2007-07-26 Fujitsu Limited Radar equipment and processing method thereof
US7613225B1 (en) * 2006-02-10 2009-11-03 Honeywell International Inc. System and method for secure communication of collected amphibious data
WO2007105607A1 (en) * 2006-03-10 2007-09-20 Semiconductor Energy Laboratory Co., Ltd. Semiconductor device
EP2002383B1 (en) 2006-03-15 2012-04-25 Semiconductor Energy Laboratory Co., Ltd. Semiconductor device
US20080012688A1 (en) * 2006-07-06 2008-01-17 Ha Dong S Secure rfid based ultra-wideband time-hopped pulse-position modulation
US7760093B2 (en) * 2006-07-26 2010-07-20 Broadcom Corporation RFID interface and applications thereof
US8344888B2 (en) * 2006-08-31 2013-01-01 Semiconductor Energy Laboratory Co., Ltd. Semiconductor device
US8188841B2 (en) * 2006-09-05 2012-05-29 Lawrence Livermore National Security, Llc Method of remote powering and detecting multiple UWB passive tags in an RFID system
US20080068173A1 (en) * 2006-09-13 2008-03-20 Sensormatic Electronics Corporation Radio frequency identification (RFID) system for item level inventory
US8868922B2 (en) * 2006-12-27 2014-10-21 Texas Instruments Incorporated Wireless authorization mechanism for mobile devices and data thereon
US8143996B2 (en) * 2007-01-08 2012-03-27 The Curators Of The University Of Missouri Decentralized radio frequency identification system
US20080186174A1 (en) * 2007-02-02 2008-08-07 Sensormatic Electronics Corporation Item level inventory with a radio frequency identification (RFID) system
US7752089B2 (en) * 2007-03-02 2010-07-06 The Curators Of The University Of Missouri Adaptive inventory management system
US8074911B2 (en) * 2007-05-14 2011-12-13 Environment One Corporation Wireless liquid level sensing assemblies and grinder pump assemblies employing the same
US7802741B2 (en) 2007-05-14 2010-09-28 Environment One Corporation Pump assemblies having a quick-release latching mechanism and methods for securing pump assemblies in a tank
US8174367B1 (en) * 2007-05-31 2012-05-08 Impinj, Inc. Causing RFID tags to backscatter more codes
US8390431B1 (en) 2007-05-31 2013-03-05 Impinj, Inc. RFID tags that backscatter more codes
US7515091B2 (en) * 2007-08-13 2009-04-07 Honeywell International Inc. Method and system for communicating using pulsed radar signal data links
US8314688B2 (en) * 2007-08-22 2012-11-20 Tagarray, Inc. Method and apparatus for low power modulation and massive medium access control
KR20100072264A (en) * 2007-09-19 2010-06-30 퀄컴 인코포레이티드 Maximizing power yield from wireless power magnetic resonators
US7864041B2 (en) * 2007-11-28 2011-01-04 Carefusion 303, Inc. Active-tag based dispensing
US8179232B2 (en) * 2008-05-05 2012-05-15 Round Rock Research, Llc RFID interrogator with adjustable signal characteristics
US8712334B2 (en) * 2008-05-20 2014-04-29 Micron Technology, Inc. RFID device using single antenna for multiple resonant frequency ranges
US20110087907A1 (en) * 2008-06-25 2011-04-14 Iiro Kristian Jantunen Power saving method and apparatus
NL2001801C2 (en) * 2008-07-14 2010-01-18 Ww I M Ltd Device and method for reducing harmful effects of electromagnetic radiation.
JP4645698B2 (en) * 2008-08-19 2011-03-09 ソニー株式会社 Wireless communication device and a power receiving apparatus
JP2010050514A (en) * 2008-08-19 2010-03-04 Sony Corp Wireless communication device and wireless communication system
US7952512B1 (en) * 2008-10-14 2011-05-31 Sprint Communications Company L.P. Mobile device enabled radar tags
US8305192B2 (en) * 2008-11-21 2012-11-06 Symbol Technologies, Inc. RFID reader with automatic near/far field interrogation mode switching, and related operating methods
US20100141385A1 (en) * 2008-12-09 2010-06-10 Mitac Technology Corp. Handheld electronic device and mobile rfid reader thereof
ES2374485T3 (en) * 2009-03-19 2012-02-17 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Method and apparatus for estimating clock skew, clock synchronization for virtual free running and to determine the position of a moving object.
JP2012528413A (en) * 2009-05-28 2012-11-12 コヴィオ インコーポレイテッド Method and system for enabling a code from the wireless device
US8660487B2 (en) * 2009-06-03 2014-02-25 Infineon Technologies Ag Contactless data transmission
WO2011017403A1 (en) * 2009-08-04 2011-02-10 Zia Systems, Llc System and method for real-time tracking of objects
JP5268844B2 (en) * 2009-09-16 2013-08-21 日立コンシューマエレクトロニクス株式会社 Wireless communication system
WO2012014787A1 (en) 2010-07-28 2012-02-02 Semiconductor Energy Laboratory Co., Ltd. Wireless power feeding system and wireless power feeding method
JP5755067B2 (en) 2010-07-30 2015-07-29 株式会社半導体エネルギー研究所 Wireless power feeding system, and a wireless power feeding method
JP5755066B2 (en) 2010-07-30 2015-07-29 株式会社半導体エネルギー研究所 Wireless power feeding system, and a wireless power feeding method
GB201013590D0 (en) * 2010-08-13 2010-09-29 Chintala Sandeep K Wireless power
US9391476B2 (en) 2010-09-09 2016-07-12 Semiconductor Energy Laboratory Co., Ltd. Power feeding device, wireless power feeding system using the same and wireless power feeding method
US8952790B2 (en) * 2010-11-18 2015-02-10 Moon J. Kim Strong passive ad-hoc radio-frequency identification
FR2967802B1 (en) * 2010-11-22 2012-11-23 Inside Contactless A GSM radio comprising a UHF tag reader
KR101854420B1 (en) 2010-11-26 2018-05-03 가부시키가이샤 한도오따이 에네루기 켄큐쇼 Power transmission device and wireless power transmission system including the same
US9054544B2 (en) 2010-12-22 2015-06-09 Semiconductor Energy Laboratory Co., Ltd. Power feeding device, power receiving device, and wireless power feed system
US9065302B2 (en) 2010-12-24 2015-06-23 Semiconductor Energy Laboratory Co., Ltd. Wireless power feeding system
KR20120084659A (en) 2011-01-20 2012-07-30 가부시키가이샤 한도오따이 에네루기 켄큐쇼 Power feeding device and wireless power feeding system
US8750345B1 (en) * 2011-02-17 2014-06-10 Olympus Corporation Asymmetric UWB radio link for wireless medical device
US9325205B2 (en) 2011-03-04 2016-04-26 Semiconductor Energy Laboratory Co., Ltd. Method for driving power supply system
US9419687B1 (en) * 2011-04-22 2016-08-16 Brian K. Buchheit Intermediate frequency broadcast of emulated passive RFID signal from a computing device
US9054749B2 (en) * 2011-06-29 2015-06-09 Broadcom Corporation Optimizing power consumption in a near field communications (NFC) environment
JP5780894B2 (en) 2011-09-16 2015-09-16 株式会社半導体エネルギー研究所 Non-contact power supply system
US9143011B2 (en) 2011-09-29 2015-09-22 Semiconductor Energy Laboratory Co., Ltd. Power receiving device and contactless power feeding system
US9496925B2 (en) 2011-09-30 2016-11-15 Nokia Technologies Oy Method, apparatus, and computer program product for remote wireless powering and control of an electronic device
WO2013079002A1 (en) * 2011-11-28 2013-06-06 浙江网新技术有限公司 Multi-frequency rfid tag, read and write device, and read and write method
US9246357B2 (en) 2011-12-07 2016-01-26 Semiconductor Energy Laboratory Co., Ltd. Contactless power feeding system
JP6088234B2 (en) 2011-12-23 2017-03-01 株式会社半導体エネルギー研究所 Power receiving apparatus, wireless power feeding system
US9391674B2 (en) 2012-04-26 2016-07-12 Semiconductor Energy Laboratory Co., Ltd. Power feeding system and power feeding method
US8933788B2 (en) * 2012-06-26 2015-01-13 Eastman Kodak Company RFID system with barriers and key antennas
EP2679279B1 (en) * 2012-06-28 2018-07-25 Zodiac Aerotechnics Oxygen breathing device and method for maintaining an emergency oxygen system
US9390850B2 (en) 2012-07-13 2016-07-12 Semiconductor Energy Laboratory Co., Ltd. Power transmitting device, power feeding system, and power feeding method
US9116237B2 (en) 2013-01-01 2015-08-25 Disney Enterprises Phase-based ranging for backscatter RFID tags
EP2779671B1 (en) 2013-03-11 2017-12-13 Nagravision S.A. Electronic support allowing access to remote audio/video assets
US9331843B2 (en) * 2013-03-15 2016-05-03 Raytheon Company Quantum synchronization for classical distributed systems
JP6128986B2 (en) * 2013-06-24 2017-05-17 任天堂株式会社 Communication system, a communication terminal apparatus, communication program, and communication method
EP2835788A1 (en) * 2013-08-06 2015-02-11 Skidata Ag Method for controlling entry and exit in multi-storey car parks and parking facilities
US9473875B2 (en) * 2014-03-06 2016-10-18 Ricoh Co., Ltd. Asymmetric wireless system
US9729201B2 (en) * 2014-04-24 2017-08-08 Empire Technology Development Llc Broadcasting a message using modulated power
EP3032836A1 (en) * 2014-12-12 2016-06-15 SmarDTV S.A. A system for providing access to conditional access media content
JP2016143971A (en) * 2015-01-30 2016-08-08 株式会社ジャパンディスプレイ Display unit
CN106157019A (en) * 2015-03-26 2016-11-23 咏嘉科技股份有限公司 Nfc payment module and control method
KR20170017164A (en) * 2015-08-05 2017-02-15 한국전자통신연구원 RFID tag having a plurality of antennas
CN105634541A (en) * 2015-12-29 2016-06-01 北京邮电大学 Full-duplex simultaneous wireless information and power transfer method and nodes

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3299424A (en) 1965-05-07 1967-01-17 Jorgen P Vinding Interrogator-responder identification system
GB1242385A (en) 1967-06-20 1971-08-11 John Edward Moffitt Identification system
US3541995A (en) 1968-11-18 1970-11-24 George H Fathauer Automatic animal feed control system
US3713148A (en) 1970-05-21 1973-01-23 Communications Services Corp I Transponder apparatus and system
US3689885A (en) 1970-09-15 1972-09-05 Transitag Corp Inductively coupled passive responder and interrogator unit having multidimension electromagnetic field capabilities
US4331971A (en) * 1980-11-19 1982-05-25 Zenith Radio Corporation Mode decision controller for selectively actuating a chrominance bandwith enhancement in a television receiver
US5677927A (en) 1994-09-20 1997-10-14 Pulson Communications Corporation Ultrawide-band communication system and method
US6834073B1 (en) * 2000-05-26 2004-12-21 Freescale Semiconductor, Inc. System and method for baseband removal of narrowband interference in ultra wideband signals
US7006553B1 (en) * 2000-10-10 2006-02-28 Freescale Semiconductor, Inc. Analog signal separator for UWB versus narrowband signals
US7050419B2 (en) * 2001-02-23 2006-05-23 Terayon Communicaion Systems, Inc. Head end receiver for digital data delivery systems using mixed mode SCDMA and TDMA multiplexing
US6550674B1 (en) 2002-08-23 2003-04-22 Yoram Neumark System for cataloging an inventory and method of use
KR100501937B1 (en) 2003-05-03 2005-07-18 삼성전자주식회사 Ultra wideband transceiver and method thereof
JP4333424B2 (en) * 2004-03-17 2009-09-16 ブラザー工業株式会社 Responder, the interrogator, and a pulse signal transmission and reception system

Cited By (43)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7573614B2 (en) * 2003-12-26 2009-08-11 Ricoh Company, Ltd. Image processing apparatus, image processing method, and computer product
US20050151991A1 (en) * 2003-12-26 2005-07-14 Naoto Shiraishi Image processing apparatus, image processing method, and computer product
US20070249314A1 (en) * 2004-03-19 2007-10-25 Sirit Technologies Inc. Adjusting parameters associated with transmitter leakage
US8432293B2 (en) * 2005-01-19 2013-04-30 Innovision Research & Technology Plc Charging a chargeable power supply of a near field communication (NFC) enabled device from a radio frequency (RF) signal inductively coupled onto a magnetic field
US20130217326A1 (en) * 2005-01-19 2013-08-22 Broadcom Innovision Limited Charging A Chargeable Power Supply of A Near Field Communication (NFC) Enabled Device from A Radio Frequency (RF) Signal Inductively Coupled Onto A Magnetic Field
US9143202B2 (en) * 2005-01-19 2015-09-22 Broadcom Europe Limited Charging a chargeable power supply of a near field communication (NFC) enabled device from a radio frequency (RF) signal inductively coupled onto a magnetic field
US20080272889A1 (en) * 2005-01-19 2008-11-06 Innovision Research & Technology Plc Nfc Communicators and Nfc Communications Enabled Devices
US20060164206A1 (en) * 2005-01-27 2006-07-27 Buckingham Duane W Reduced power electronic lock system
US8354914B2 (en) * 2005-01-27 2013-01-15 Inncom International, Inc. Reduced power electronic lock system
US20070063013A1 (en) * 2005-09-19 2007-03-22 Lexmark International, Inc. Systems and methods for maintaining warranty claim information
US8226003B2 (en) 2006-04-27 2012-07-24 Sirit Inc. Adjusting parameters associated with leakage signals
US20080151313A1 (en) * 2006-12-21 2008-06-26 Konica Minolta Business Technologies, Inc. Image monitoring system for preventing confidential information outflow, image monitoring method, and computer image monitoring program stored on a computer readable medium
US8049913B2 (en) 2006-12-21 2011-11-01 Konica Minolta Business Technologies, Inc. Image monitoring system for preventing confidential information outflow, image monitoring method, and computer image monitoring program stored on a computer readable medium
US20100107985A1 (en) * 2007-03-22 2010-05-06 Faire (Ni)Limited Animal monitoring system and method
US9198400B2 (en) * 2007-03-22 2015-12-01 Faire (Ni) Limited Animal monitoring system and method
US8248212B2 (en) 2007-05-24 2012-08-21 Sirit Inc. Pipelining processes in a RF reader
US20090015371A1 (en) * 2007-07-10 2009-01-15 Xavier Bocquet System and method of controlling access to services
US8674808B2 (en) * 2008-02-29 2014-03-18 Nokia Corporation Interrogation of RFID communication units
US20100328043A1 (en) * 2008-02-29 2010-12-30 Nokia Corporation Interrogation of rfid communication units
US8427316B2 (en) 2008-03-20 2013-04-23 3M Innovative Properties Company Detecting tampered with radio frequency identification tags
US20090267746A1 (en) * 2008-04-23 2009-10-29 Martec Corporation Multi-Port Receiver
US8446256B2 (en) 2008-05-19 2013-05-21 Sirit Technologies Inc. Multiplexing radio frequency signals
US20090284354A1 (en) * 2008-05-19 2009-11-19 Sirit Technologies Inc. Multiplexing Radio Frequency Signals
US20110298619A1 (en) * 2008-12-11 2011-12-08 Faire (Ni) Limited Animal monitoring system and method
US20100176921A1 (en) * 2009-01-09 2010-07-15 Sirit Technologies Inc. Determining speeds of radio frequency tags
US8169312B2 (en) 2009-01-09 2012-05-01 Sirit Inc. Determining speeds of radio frequency tags
US20100277284A1 (en) * 2009-05-01 2010-11-04 Brown Jonathan E Data separation in high density environments
US20100277286A1 (en) * 2009-05-01 2010-11-04 Burkart Scott M Synchronization of devices in a RFID communications environment
US8368513B2 (en) * 2009-05-01 2013-02-05 L-3 Communications Integrated Systems L.P. Data separation in high density environments
US20100277283A1 (en) * 2009-05-01 2010-11-04 Burkart Scott M Systems and methods for RFID tag operation
US20100277280A1 (en) * 2009-05-01 2010-11-04 Burkart Scott M Systems and methods for relaying information with RFID tags
US8456282B2 (en) * 2009-05-01 2013-06-04 L-3 Communications Integrated Systems L.P. Synchronization of devices in a RFID communications environment
US20100289623A1 (en) * 2009-05-13 2010-11-18 Roesner Bruce B Interrogating radio frequency identification (rfid) tags
US20100302012A1 (en) * 2009-06-02 2010-12-02 Sirit Technologies Inc. Switching radio frequency identification (rfid) tags
US8416079B2 (en) 2009-06-02 2013-04-09 3M Innovative Properties Company Switching radio frequency identification (RFID) tags
US20110159817A1 (en) * 2009-12-29 2011-06-30 Pirelli Tyre S.P.A. Method and system for managing communications between sensor devices included in a tyre and a sensor coordinator device
US20110205025A1 (en) * 2010-02-23 2011-08-25 Sirit Technologies Inc. Converting between different radio frequencies
US9124358B2 (en) * 2010-11-29 2015-09-01 Kourosh Pahlavan Passive wireless connection
US20120134389A1 (en) * 2010-11-29 2012-05-31 Tagarray, Inc. Passive wireless connection
US10062025B2 (en) 2012-03-09 2018-08-28 Neology, Inc. Switchable RFID tag
CN103854469A (en) * 2012-11-28 2014-06-11 苏州工业园区新宏博通讯科技有限公司 Collector
WO2016106194A1 (en) * 2014-12-22 2016-06-30 Datalogic IP Tech, S.r.l. Ultra-wideband location engine for self-shopping devices
US9435877B2 (en) 2014-12-22 2016-09-06 Datalogic Ip Tech S.R.L. Ultra-wideband location engine for self-shopping devices

Also Published As

Publication number Publication date Type
JP4934050B2 (en) 2012-05-16 grant
CN101160608A (en) 2008-04-09 application
US7180421B2 (en) 2007-02-20 grant
US20060103535A1 (en) 2006-05-18 application
JP2008521287A (en) 2008-06-19 application
CN101160608B (en) 2010-10-27 grant

Similar Documents

Publication Publication Date Title
US6463039B1 (en) Method and apparatus for full duplex sideband communication
Curty et al. Design and optimization of passive UHF RFID systems
US5485154A (en) Communication device and method(s)
US7317378B2 (en) Product identification tag device and reader
US6838989B1 (en) RFID transponder having active backscatter amplifier for re-transmitting a received signal
US20080266060A1 (en) Transmitter and wireless system using the same
US20070001813A1 (en) Multi-reader coordination in RFID system
US5649296A (en) Full duplex modulated backscatter system
US20070096875A1 (en) Radio tag and system
US5929779A (en) Read/write protocol for radio frequency identification tags
US20070115827A1 (en) Wireless communication network architecture
US6459726B1 (en) Backscatter interrogators, communication systems and backscatter communication methods
US6324211B1 (en) Interrogators communication systems communication methods and methods of processing a communication signal
US20100328043A1 (en) Interrogation of rfid communication units
US5974078A (en) Modulated spread spectrum in RF identification systems method
US20120045989A1 (en) Device discovery in near-field communication
US20090117872A1 (en) Passively powered element with multiple energy harvesting and communication channels
US7026935B2 (en) Method and apparatus to configure an RFID system to be adaptable to a plurality of environmental conditions
US7091828B2 (en) Interrogators, methods of operating a coherent interrogator, backscatter communication methods, interrogation methods, and signal processing methods
US8063769B2 (en) Dual band antenna and methods for use therewith
Kellogg et al. Wi-Fi backscatter: Internet connectivity for RF-powered devices
US20050024187A1 (en) System and method for optimizing power usage in a radio frequency communication device
US6600905B2 (en) Communication system, interrogators and communication methods
Zhang et al. RFID and sensor networks: architectures, protocols, security, and integrations
US20050156039A1 (en) Radio frequency identification reader