MXPA06001095A - System and method for optimizing power usage in a radio frequency communication device - Google Patents

Abstract

A radio frequency (RF) communication device is provided comprising means for switching between a low current operating mode and a high current operating mode. The low current operating mode is optimized to conserve power while the RF device is awaiting a wake-up signal from an interrogator. The high current operating mode is optimized to provide antenna matching during backscatter communications so as to maximize the range of backscatter communication between the RF device and the interrogator. Further provided, is a system and method for optimizing power consumption and backscatter range within an RF communication device.

Description

Published: For two-letter codes and other abbreviations, referto the "Guid¬ - without international search report and to be republished ance Notes on Codes and Abbreviations "appearing at the beginning of the receipt of that report no ofeach regular issue ofihe PCT Gazette.

SYSTEM AND METHOD TO OPTIMIZE THE USE OF ENERGY IN A FREQUENCY COMMUNICATION DEVICE RADIO CROSS REFERENCE WITH RELATED REQUESTS This application claims priority in accordance with U.S.C § 119 (e) of the Provisional Paternity Application Serial No. 60 / 490,575, filed on July 28, 2003, entitled "Swiíchable Bias on Frequency Hopping RFID Tags ", whose description is incorporated here as a reference in its identity.

FIELD OF THE INVENTION The present invention is related to systems and method to increase the range of communication and prolong the life of the battery in a radio frequency communication device. More particularly, the present invention relates to systems and methods for improving the general use of energy in an RFID radio frequency identification device.

BACKGROUND OF THE INVENTION Remote communication with the use of wireless equipment may be based on radio frequency (RF) technology. An application of RF technology is to locate, identify and track objects, such as animals, equipment and vehicles. Other applications of RF technology may include the communication of damage collected from remote sensors. Systems of RF idenification (RFID) have been developed to facilitate the monitoring of remote targets and communicate the damage collected from remote sensors. As shown in Figure 1, a basic RF tag system 10 may include three components, an anchor 12, a transceiver with decoder 14, and a transponder (commonly called RFID tag) 16. During the operation, the antenna 12 may emit electromagnetic radio signals generated by the transceiver 14 to activate the RFID 16 tag. When the RFID eíiqueía 16 is activated, the damages can be read or written in the RFID eíiquefa 16. In some applications, the element 12 can be a component of the transceiver and the decoder to become an interrogator (or reader) 18. The interrogator 18 can activate or "wake up" the RFID tag 16 by irradiating energy in the tag in an ignition pattern. / off coded in a variable time form. When an RFID tag 16 passes electromagnetic radio waves 20, the RFID tag 16 detects the signal and activates. An example of a widely used way to activate RFID tagging is the bi-phase encoding. When the interrogator 18 speaks with the RFID method, the injector 18 then engages in a coninuous transmission of energy that the RFID system uses to communicate the information to the inerrorist by means of re-scattering meyhodologies. The daphics encoded in the RFID effigy 16 can communicate to the interrogator 18 via a daph signal 22 through the antenna 23. The RFID technique can modulate its signal and place a sub-porker in the backscatter carrier signal of the interrogator that can then exile and demodulate. The sub-pointer can use a displacement modulation technique of variable amplitude of time, such as biphase modulation to encode the data within the signal of the sub-carrier. RFID communication systems can include systems where RFID returns return damage to a specific frequency associated with each RFID system. For example, an interrogator can transmit a signal at a frequency, and each RFID tag can modulate the amplitude of its signal at a frequency separate from the frequency of any other RFID tag in the system. Such systems may allow the interrogator to simultaneously differentiate the information received from multiple RFID tags. In addition, the RFID tags can be configured to allow the labeling to be communicated to one of different frequencies and to adaptively adapt the inferences with other signals that can be communicated on an identical frequency. While an RFID tag can adaptively change the frequency at which it is communicated, the medium for communicating information still relies on a method to modulate the amplitude of the signal in a variable form of time to encode damage to the signal. In what is known in the semi-passive eíiqueía, the eíiqueía uses battery energy to hear the signal of "awakening" of the interrogator. Once the interrogator and the tag have established communication, the tagger also uses the battery power to modulate its antenna. By combining with the interrogator through amphenar modulations rather than actively transmuting the RF signal, the labeling uses much less energy than the active transmission label. This configuration minimizes energy consumption, since the battery is only used for the "wake up" signal and modifies the alarm to communicate the information back to the injector. However, the actual energy needed during the listening mode differs greatly from the energy needed for the modulation or the backscatter mode. The listening mode requires less energy since the tag is essentially inactive and waits for a signal from the interrogator. A small current is required to provide the reference voltage to the comparator for use in deciphering the RF signals received from the antenna. During the backscatter mode, more energy is required to provide a polarization current to the diodes, which decreases their equivalent RF resistance, which causes them to better match the impedance of the antenna. This increases the resonance response of the antenna, which causes more energy to be reflected from the interrogator. This increase in the energy distributed regressively increased the range in which the energy can be read.

Unforgivenly, in order to polarize the dies in an optimal way for purposes of re-scattering, a small resistor must be used for the charge. This means that when the label hears a signal, the rectified signal input from the antenna will be coupled poorly with the comparator circuit. For an ideal listening circuit, the system should have a very low current in the recited signal. However, this results in a deficient backscattering range. Current labeling configurations face the challenge of opiimizing a system with two compelling power requirements. The current solution is to polarize the diode switches at the same point that is not optimal for the wake-up or backscatter modes, rather, at some point between them. Frequently, the label is optimized for power consumption during listening mode, which decreases the backscatter range, but prolongs battery life. Therefore, it would be desirable to provide a system and method with two different operating modes, with the ability to switch the load / bias between an impedance load appropriate to the listening mode and a low impedance load that offers a range of backscatter increased, so as to optimize the range of refrodispersion and battery life conditions. These needs are covered by the present invention.

BRIEF DESCRIPTION OF THE INVENTION In a first aspect of the present invention, an RF transponder is provided, which comprises an amphenia which operates to receive RF signals from an interrogator and communicate the information back to the interrogator, a power source, and a signal processing circuit in communication with the antenna and the power source, which comprises a means for switching between a low current operating mode and an operating alpha current mode. In one embodiment of the present invention, the means for switching from an operating mode of low current to an operating mode of current operation comprises a switchable resistor for connecting or disconnecting from the circuit. The low current operating mode is defined by a high impedance voltage within the circuit and the high current operating mode is defined by a low impedance voltage within the circuit. In another embodiment of the present invention, a signal processing circuit of the RF transponder comprises two resistors, a first resistor comprises a first resistive value and a second resistor comprises a second resistive value less than the first resistive value. In a preferred embodiment of the present invention, the first resistive value is at least 103 times greater than the second resistive value. In another preferred embodiment of the present invention, the resistive value of the first resistor is selected to optimize the energy consumption by providing a voltage of alias impedance to the system, and the resistive value of the second resistor is selected to optimize the range of backscatter by matching the impedance of the circuit to approximately that of the antenna. In another embodiment of the present invention, the signal processing circuit of the RF transponder also comprises a comparator and a microcontroller. Preferably, the switching means is integrated into the microcontroller and the microcontroller is coupled with the second resistor based on the signals received from the comparator to switch between the low current mode and the high current mode. In another embodiment of the invention, the RF transponder antenna communicates feedback back to the interrogator through the backscatter methodology. In another aspect of the present invention, there is presented an RF communication system, a transponder as described above, an interrogator and a sensor wherein the sensor is in electrical communication with the RF transponder. The system is also defined where the RF transponder operates in a low current mode until an interrogator signal is received by the antenna, and after signal reception, the RF transponder is switched with a high current operating mode and communicates the information received from the sensor to the interrogator through the regimes of re-scattering. In another aspect of the present invention, an operating mode of low current is defined by a high impedance voltage within the circuit, the high current operating mode is defined by a low impedance voltage within the circuit. In addition, the signal processing circuit can comprise two resistors, a first resistor comprises a first resistive value and a second resistor comprises a second resistive value smaller than the first resistive value. In a preferred embodiment of the present invention, the first resistive value is at least 103 times greater than the second resistive value. In another aspect of the present invention, a method is described for optimizing the energy consumption in an RF transponder, characterized in that it comprises providing an RF transponder in communication with the antenna and the energy source, and offers a processing circuit for signal in communication with the antenna and the power source, which comprises a means for switching between a low current operating mode and a high current operating mode in response to a signal received from the interrogator. The signal processing circuit operates in the low current operating mode to conserve energy while waiting for a wake-up signal from the interrogator, and when the wake-up signal is received by the antenna and processed by the signal processing circuit , the signal processing circuit is switched to a high current operating mode. The operating mode of low current is optimized to receive a wake-up signal from the injector and the high-current operating mode is optimized for commuting the information to the operator through the refrodispersion methodologies. The characteristics of a system and a method for optimizing energy consumption in an RF communication device of the present invention can be achieved in a singular manner, or in combination, in one or more of the methods of the present invention. As will be appreciated by persons skilled in the art, the invention is widely used in many applications as illustrated by a variety of features and advantages described below. A system and method for opiimizing the energy consumption in an RF communication device of the present invention provides several advantages over the above RF communication device configurations. For example, the present invention advantageously offers optimization of the backscattering range while also providing the ability to optimize power consumption during listening mode. As will be appreciated by persons skilled in the art, many different modalities of a system and method for optimizing energy consumption in an RF communication device are possible. The uses, objectives, advantages and novel features of the invention are described in the detailed description that follows, and will be evident to those experienced in the art after studying or practicing the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram that shows the communication between an interrogator and an RF tag. Figure 2 is a diagram of a typical RFID tag system comprising a flag and a plurality of tags. Figure 3 is a diagram of an RFID communication system comprising an interrogator and an RFID tag. FIG. 4 is a schematic of an RFID tag in accordance with an embodiment of the present invention that shows an additional resistor, switch, coupled to provide a low impedance load to increase the bias current during the backscatter mode.

DETAILED DESCRIPTION OF THE INVENTION In a first aspect of the present invention, a radio frequency (RF) communication device is provided, which comprises means for switching between a low current operating mode and a high current operating mode. The low current operating mode is optimized to conserve energy while the RF device waits for a wake-up signal from the interrogator. The high current operating mode is optimized to provide an anchor match during the re-scatter communications in order to maximize the range of backscatter communication between the RF device and the interrogator. In a preferred embodiment of the present invention, the remote RF communication device comprises a radio frequency identification tag. The description of the preferred embodiments of the present invention will be described with reference to the RF label and an RF transponder as the RF communication device. In one aspect of the present invention, the RF communication system comprises an interrogator and at least one RF communication device comprising an RF tag: Referring now to FIG. 2, a diagram of one embodiment of an RF system is shown. communication of the present invention. The communication system 210 comprises an interrogator 212 and a plurality of communication devices 214, 216 and 218. Each remote communication device 214, 216 and 218 within the system 210 comprises: an antenna 226 of the remote communication device that operates to receive and backscatter a signal 222 from the porker. The signal 224 of the refrodispersed portion comprises the carrier signal and a secondary signal with data encoded therein. The remote communication devices 214, 216 and 218 also comprise a signal processing circuit coupled to the antenna 226 of the remote communication device. The signal processing circuit comprises at least one encoder circuit that operates to encode binary data within the signal of the backscattered carrier. The injector 212 comprises an array 220 which operates to receive a plurality of re-dispersed chips 224 from the porror, re-scattered from the plurality of remoting communication devices 214, 216, and 218. The interrogator 212 also comprises a receiver circuit coupled to the antenna 220 which operates to extract damage from each of the re-dispersed portion signals 224. Although mobile devices 214, 216 and 218 are illustrated, the system 210 may comprise any number of remote communication devices. In another embodiment of the present invention, the interrogator 212 may also comprise a transmitter circuit coupled to the anise 220, wherein the transmitter circuit operates to transmit a signal 222 from the pointer to the plurality of communication devices 214, 216 and 218. remofos. In another embodiment, the antenna 220 may comprise a transmitting antenna coupled with the transmitting circuit and the receiving antenna coupled with the receiver circuit. In another embodiment, the remote communication antenna 220 and the signal processing circuit of the remote communication devices can be configured to generate a supply voltage of the carrier signal. In another modality of the communication system 210, the communication devices 214, 216 and 218 can also comprise a sensor coupled with the signal processing circuit, wherein the signal processing circuit also operates to receive a signal from the sensor, encode the sensor signal and include the signal. sensor signal encoded in the secondary signal of signal 224 of the backscattered carrier. As used herein, the sensor includes any device that derives the absolute value of or a change in physicality such as, but not limited to, temperaure, pressure, light intensity, and acceleration. For example, any pressure sensor known in the art can be used in the practice of the present invention, as long as it can be functionally connected with the removed communication device. In one embodiment, the pressure sensor may comprise a piezoelectric pressure sensor where the volume is applied through a diaphragm coated with piezo-crystals. Those skilled in the art will recognize that other sensor means may be employed in the different embodiments of the invention without departing from the spirit and scope of the present invention. The devices, systems and methods of the embodiments of the present invention can employ many RFID hardware technologies known to those skilled in the art, which have been added to the present invention. Hardware methods can vary widely from the scope of the present invention, but the principles of switching between two different energy consumption modes can be applied in many hardware configurations. For example, the microcontrollers available here could be, but were not limited to, a series of MSP 430 microcontrollers from Texas Insírumenfs, which include a mounted ring or an RC oscillator that can be adjusted in steps. The microcontroller may act as the switch for the additional resistor (Rswitch) of the present invention. With the use of pre-existing hardware, the systems and methods of the present invention can be employed at no additional cost to the system. With reference to Figure 4, which shows a simplified scheme of the concepts of one embodiment of the present invention, the RF communication device comprises an antenna 110, a power source, and signal processing circuitry. The signal processing circuitry comprises a comparator 130, and a microcontroller 140. The comparator 130 compares the signals received by the signal 110 to a reference signal 132 and supplies the results to the microcontroller 140. The microcontroller 140 controls the memory functions a short term and computing in the eíiqueía. Further, the microcontroller 140 accepted signals from the sensor 138 and encodes the signals to communicate them back to the interrogator through the backscattering methodologies of the antenna 110. In a preferred embodiment of the present invention, the means for switching between an operational mode of low current and a high current operating mode comprises the addition of a low load resistor 160 (Rswitch) and a switch for coupling and uncoupling the low load resistor with the input of the microcontroller. When the signal processing circuit in the RF communication device detects a signal entering from the antenna, the switch changes the low load resistor 160 to "on" which bypasses the primary resistor 1 50 (Rload) and provides more current to the system. In a preferred embodiment of the present invention, the low-current operating mode provides a low current level to the system. This low current volume is achieved through the high impedance provided by the high load resistor 1 50 (Rload) -It provides the necessary vol- ume to the comparator to effect the defection and comparison of an RF signal from the 1 1 1 an. An RF communication device may be "inactive" in a low current operating mode for long periods of time before an signal is received from the inerror. When operating in a low run mode during this time, the RF communications device can wait for instructions from the interrogator as long as it uses a minimum amount of energy. When a signal was detected by the signal processing circuit, the circuit switched to the current alias mode. In a preferred embodiment of the present invention, the low load resistor 160 is selected such that the high current operating mode produces a high polarization current (lpoiarization) for the system and particularly for the amphenia. The desired effect is a high coincidence of the antenna, so that the impedance of the circuit is close to that of the antenna. By providing a low impedance source and therefore a high load to the antenna, so that the source impedance matches the impedance of the antenna, the backscattering range of the RF communication device can be maximized for a given system . In one embodiment of the present invention, provided to illustrate an exemplary configuration, the RF tag comprises a power source of 2.8 volts. In this configuration, the previous systems had a standard load resistor of approximately 1 Mega ohms to allow a relatively good backscattering range up to 10 Mega ohms to reduce the power consumption during the listening mode. In any case, the range of re-scattering can not be optimized due to the exiration in the basin during the listening mode. The present invention replaces this configuration with a load resistor 150 (Rcharge) of between about 1 and 10 Mega ohms and a low load resistor 160 (commutator) of about 1000 ohms. In the present configuration, power consumption can be minimized through the high load resistor, and the low load resistor can provide antenna matching during backscattering. In this example, the difference in resistance between Rcarga and The ratio is approximately 103 to 104. This allows the RF tagging to provide ample power between the low-current and high-current operating modes to provide significant energy savings during listening mode and an almost perfect match achieved during mode. of reírodispersión. Through this configuration and technique, the backscatter range will typically be doubled compared to a traditional RF tag optimized for power consumption. In an exemplary embodiment of this feature, a prior art system optimized for power consumption employed a 1 Mega ohm load resistor. The system was capable of backscattering approximately 1.50 m when introduced into a 1 megawaffe interrogator. For the present, the system of the present invention employs a 1 Mega ohm load resistor and a 2.5 kilo-ohm commutable resistor and can re-scatter 1.50 m without loss in reception. This reflects an increase of three bends in the backscatter range compared to a similar previous system. The exact values for RCarga and for Rcommutator, will be able to be recognized by those experienced in the technique for a given RF transponder and will be designated based on the needs of the system. However, the principles shown here can be applied to RF transponders that will benefit from having two operating modes comprising two different power requirements. As mentioned before, the ideal system will provide a high resistive value for Rload in order to reduce the energy usage during the listening mode and an appropriate resistive value for the Rswitch to provide an antenna match and maximize the backscattering range. Although the present invention has been described with reference to the parficular modalities, it may be recognized that the modalities are merely illusive of the principles of the present invention. Those skilled in the art will appreciate that the apparatuses and methods of the present invention can be constructed and implemented in other forms and modalities. Accordingly, the description should not be considered as limiting the present invention, as well as other embodiments that fall within the scope of the present invention.

Claims (10)

1. REVIVAL DICTION EN
2. 1 . An RF transponder, characterized in that it comprises: an antenna that operates to receive RF signals from an interrogator and communicate the information back to the interrogator; a source of energy; and a signal processing circuit in communication with the antenna and the power source, comprising a means for switching between an operating mode of low current and an operating mode of alpha current. The RF transponder according to claim 1, characterized in that the means for switching between a low current operating mode and a high current operating mode comprises a switchable resistor that operates to connect and disconnect from the circuit.
3. 3. The RF transponder according to claim 1, characterized in that the low current operating mode is defined by a high impedance voltage within the circuit.
4. 4. The RF transponder according to claim 1, characterized in that the high current operating mode is defined by a low impedance voltage within the circuit.
5. 5. The RF transponder according to claim 1, characterized in that the signal processing circuit comprises two resistors, a first resistor comprises a first resistive value, and a second resistive value comprising a second resistive value less than the first resistive value.
6. 6. The RF transponder according to claim 5, characterized in that the first resistive value is at least 1 03 times greater than the second resistive value.
7. 7. The RF transponder according to claim 1, characterized in that the first resistive value of the first resistor is selected to optimize the power consumption to provide a high impedance voltage for the system. The RF transponder according to claim 1, characterized in that the resistive value of the second resistor is selected to optimize the backscattering range by equalizing the impedance of the circuit to approximately that of the antenna. 9. The RF transponder according to claim 1, characterized in that the signal processing circuit also comprises a comparator and a microcontroller. 10. The RF transponder according to claim 9, characterized in that a switching means is integrated within the microcontroller and the microcontroller is coupled with the second resistor based on the signals received from the comparator to switch between the low current mode and the high current mode.

   eleven . The RF transponder according to claim 1, characterized in that the antenna communicates information back to the interrogator through backscattering methodologies. 12. An RF communication system characterized in that it comprises an RF transponder of claim 1, an interrogator and a sensor, characterized in that the sensor is in electrical communication with the RF transponder: 13. The RF communication system in accordance with the claim 12, characterized in that the RF transponder operates in a low current mode until a signal is received from the interrogator by the antenna, after the reception of the signal, the RF transponder switched to an operational mode of the current and communicates the information received from the sensor to the interrogator through backscattering methodologies. 14. The RF communication system according to claim 12, characterized in that the low-current operating mode is defined by a high-impedance voltage within the circuit. 15. The RF communication system according to claim 12, characterized in that the high current operating mode is defined by a low impedance voltage of the circuit. 16. The RF communication system according to claim 12, characterized in that the signal processing circuit comprises two resistors, a first resistor comprises a first resistive value, and a second resistive value comprising a second resistive value less than the first resistive value. resistive value. 17. The RF communication system according to claim 16, characterized in that the first resistive value is at least 103 times greater than the second resistive value.
8. 8. A method for optimizing energy consumption in an RF transponder, characterized in that it comprises: providing an RF transponder comprising an amphenia and a signal source; and providing a signal processing circuit in communication with the antenna and the power source, which comprises a means for switching between a low current operating mode and an operating mode of the current in response to a signal received from the inlerator.; where the signal processing circuit operates in the low-current operating mode to conserve energy while waiting for a signal to be heard from the interrogator, and when the wake-up signal is received by the antenna and processed by the processing circuit. of signal, the signal processing circuit is switched to a high current operating mode. 19. The method according to claim 18, characterized in that the low current operating mode is optimized to receive a wake-up signal from the interrogator. 20. The method according to claim 18, characterized in that the high current operating mode is optimized to communicate information to the interrogator through backscattering methodologies.

   SUMMARY

   A radio frequency (RF) communication device is provided which comprises a means for switching between a low current operating mode and a high current operating mode. The low current operating mode is optimized to conserve energy while the RF device waits for a wake-up signal from an interrogator. The high current operating mode is optimized to provide an antenna match during the re-scatter communications to maximize the range of re-scatter communication between the RF device and the interrogator. In addition, a system and method for optimizing energy consumption and the range of refrodispersion within the RF communication device will also be provided.