In-building modulated backscatter system
First Claim
1. A communication system comprising at least one control element adapted to transmit data to at least one interrogator, at least one interrogator adapted to transmit a modulated radio signal to at least one tag, and at least one mag adapted to form a reflected modulated signal for reception by at least one said interrogator, wherein:
- interrogator comprises a generator of a First Information Signal, the First Information Signal having contents taken, at least in part, from data received from the control element;
the interrogator further comprises a modulator, responsive to the First Information Signal generator, adapted to modulate a radio signal with the First Information Signal, thereby to generate the modulated radio signal;
the tag comprises a generator of a subcarrier signal, and a modulator adapted to modulate the subcarrier signal using a Second Information Signal, thereby to generate a modulated subcarrier signal;
the tag further comprises a backscatter modulator adapted to modulate a reflection of the modulated radio signal using the modulated subcarrier signal, thereby to form the reflected modulated signal;
the interrogator further comprises a demodulator adapted to demodulate the reflected modulated signal, thereby to recover the Second Information Signal;
the interrogator further comprises means for determining one or more characteristics of the Second Information Signal;
the interrogator further comprises means for transmitting, to the control element, data that comprise at least some contents of, or one or more characteristics of, the Second Information Signal; and
the control element comprises means for determining the location of a specific said tag.
5 Assignments
0 Petitions
Accused Products
Abstract
In accordance with the present invention, a radio communications system is disclosed that can operate in one of several Modes which integrate in-building security, location determination, messaging, and data communications capabilities. The radio communication system includes at least one Interrogator for generating and transmitting a radio signal. One or more Tags of the system receive the radio signal. A Backscatter Modulator modulates the reflection of the radio signal using a subcarrier signal, thereby forming a reflected modulated signal. The Interrogator receives and demodulates the reflected modulated signal. The Interrogator can also transmit a first information signal to one or more tags, specifying which tags should respond using the Backscatter Modulator. In the Interrogation Mode, the Interrogator can determine the identity of the Tags in the reading field, and can exchange data with those Tags that have been identified. In the Location Mode, the radio communications system can instruct some or all Interrogators to determine the location of a Tag or Tags within the building, regardless of whether the Tag or Tags are in radio range of the Interrogation Mode. In the Messaging, or low speed data communications Mode, the radio communications system can instruct some or all Interrogators to transmit a command addressed to a particular Tag or Tags, regardless of whether the Tag or Tags are in the reading field of the Interrogation Mode, questing that Tag or Tags perform some action. Other embodiments of the Messaging Mode allow the Interrogator to transmit data in addition to a command to the Tag or Tags, and also for the Tag or Tags to transmit a signal back to the Interrogator. This radio communications system can be interconnected with other communications capabilities such as electronic mail, voice mail, location, inventory management, and other systems.
446 Citations
38 Claims
-
1. A communication system comprising at least one control element adapted to transmit data to at least one interrogator, at least one interrogator adapted to transmit a modulated radio signal to at least one tag, and at least one mag adapted to form a reflected modulated signal for reception by at least one said interrogator, wherein:
-
interrogator comprises a generator of a First Information Signal, the First Information Signal having contents taken, at least in part, from data received from the control element; the interrogator further comprises a modulator, responsive to the First Information Signal generator, adapted to modulate a radio signal with the First Information Signal, thereby to generate the modulated radio signal; the tag comprises a generator of a subcarrier signal, and a modulator adapted to modulate the subcarrier signal using a Second Information Signal, thereby to generate a modulated subcarrier signal; the tag further comprises a backscatter modulator adapted to modulate a reflection of the modulated radio signal using the modulated subcarrier signal, thereby to form the reflected modulated signal; the interrogator further comprises a demodulator adapted to demodulate the reflected modulated signal, thereby to recover the Second Information Signal; the interrogator further comprises means for determining one or more characteristics of the Second Information Signal; the interrogator further comprises means for transmitting, to the control element, data that comprise at least some contents of, or one or more characteristics of, the Second Information Signal; and the control element comprises means for determining the location of a specific said tag. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
-
-
19. A communication system comprising:
-
at least one interrogator adapted to modulate a radio signal with a First Information Signal, resulting in a modulated radio signal, and further adapted to transmit the modulated radio signal to at least one tag; and at least one tag adapted to receive the modulated radio signal and to form therefrom a reflected modulated signal for reception by at least one said interrogator, wherein; the tag comprises a generator of a subcarrier signal, and a modulator adapted to modulate the subcarrier signal using a Second Information Signal, thereby to generate a modulated subcarrier signal; the tag further comprises means, responsive to the First Information Signal, for determining at least some content, data rate or modulation of the Second Information Signal based on contents of the First Information Signal; the tag further comprises a backscatter modulator adapted to modulate a reflection of the modulated radio signal using the modulated subcarrier signal, thereby to form the reflected modulated signal; the interrogator further comprises a demodulator adapted to demodulate the reflected modulated signal, thereby to recover the Second Information Signal; the interrogator further comprises means for determining one or more signal quality characteristics of the Second Information Signal; the interrogator further comprising means, responsive to one or more said signal quality characteristics of the Second Information Signal, for making a determination whether the tag should alter the content, data rate, or modulation of the Second Information Signal; and the interrogator further comprises means for conforming the First Information Signal to this determination. - View Dependent Claims (20)
-
-
21. A communication system comprising at least one tag, said tag comprising:
-
means for receiving a radio signal; means for determining whether to transmit an unsolicited message; means for generating a subcarrier signal; means for providing an information signal that indicates or describes said unsolicited message; means for modulating the subcarrier signal with the information signal, thereby to form a modulated subcarrier signal; and backscatter-modulator means for modulating a reflection of the radio signal using the modulated subcarrier signal, thereby to form a reflected modulated signal. - View Dependent Claims (22, 23)
-
-
24. A communication system comprising at least one tag, the tag comprising:
-
means for receiving a radio signal; means for generating at least two subcarrier signals; means for detecting at least one condition in response to which a message is to be transmitted; means for selecting, for generation, a particular one of said at least two subcarrier signals when at least one said condition is detected, said particular subcarrier signal to be referred to as Subcarrier A; means for modulating Subcarrier A with an information signal that comprises an indication or description of said condition, thereby to form a modulated subcarrier signal; and backscatter modulator means for modulating a reflection of the radio signal using the modulated subcarrier signal, thereby to form a reflected modulated signal. - View Dependent Claims (25, 26)
-
-
27. An interrogator, comprising:
-
means for transmitting a radio signal to at least one tag; means for receiving a reflected modulated signal from at least one said tag; and means for demodulating the reflected modulated signal to obtain a modulated subcarrier signal, said demodulation means configured to demodulate said reflected modulated signal at one of at least two subcarrier frequencies, to be denoted Subcarrier Frequency A and Subcarrier Frequency B, wherein said Subcarrier Frequency A and said Subcarrier Frequency B correspond to different operating modes. - View Dependent Claims (28, 29, 30, 31)
-
-
32. A communication system comprising:
- a messaging system;
at least one control element adapted to receive transmitted downlink data from the messaging system and to transmit at least some of the downlink data to at least one interrogator;
at least one interrogator adapted to transmit at least some of the downlink data to at least one tag using modulated radio signals; and
at least one tag, wherein;the tag comprises means for transmitting uplink data to the interrogator using modulated backscatter radio communications; the interrogator comprises means for transmitting at least some of the uplink data to the control element; and the control element comprises means for transmitting at least some of the uplink data to the messaging system. - View Dependent Claims (33)
- a messaging system;
-
34. A communication system comprising:
- at least one control element;
at least one tag;
a location system comprising means for transmitting, to the control element, a location request to locate a specific said tag; and
at least one interrogator, wherein;the control element comprises means for transmitting the location request to the interrogator; the interrogator comprises means for transmitting the location request to at least one said tag using modulated radio signals; the tag comprises means for determining whether it is an addressee of a given location request received from the interrogator, such determination to be referred to as a positive determination if said tag is an addressee; the tag further comprises means for transmitting an uplink signal to the interrogator, using modulated backscatter radio communications, only in case of a positive determination; the interrogator further comprises means for taking measurements of one or more characteristics of the uplink signal, and for transmitting one or more said measurements to the control element; and the control element further comprises means for receiving said one or more measurements, means for determining the location of the tag, and means for transmitting resulting location information to the location system. - View Dependent Claims (35, 36, 37)
- at least one control element;
-
38. A communication system, comprising:
at least one control element;
at least one tag;
at least two interrogators, each adapted to receive downlink data from the control element and to transmit downlink data to at least one said tag; and
a messaging system adapted to transmit downlink data to at least one said control element, wherein;at least one said tag is adapted to transmit uplink data to at least one said interrogator using modulated backscatter radio communications; and
at least one said interrogator is adapted to transmit at least some of the uplink data to the messaging system;the control element comprises means for determining the location of at least one selected tag, the control element further comprises means for transmitting at least some of the downlink data, using modulated radio signals, to at least one interrogator selected for transmission of downlink data to at least one said selected tag, and the control element further comprises means for designating said selected interrogator based upon the location of at least one said selected tag.
Specification