Reflective communication using radio-frequency devices
First Claim
1. A reflective communication system, comprising:
- a plurality of transmitters configured to operate on the same frequency, wherein each transmitter of the plurality of transmitters is physically separate from the rest of the plurality of transmitters, and wherein each transmitter of the plurality of transmitters is configured to transmit a communication signal that is spread with a spread spectrum code associated with the transmitter;
a plurality of wireless communication devices located in the transmission field of the plurality of transmitters and configured to receive communication signals transmitted from the plurality of transmitters, wherein the plurality of wireless communication devices are further configured to reflectively modulate the communication signals with data signals having a modulation to form reflected data signals; and
a receiver configured to;
store, in a receiver memory, a spread spectrum coding sequence containing a plurality of receiver spread spectrum codes, wherein each receiver spread spectrum code correlates to a spread spectrum code respectively associated with a transmitter of the plurality of transmitters;
store, in the receiver memory, information indicating a physical location of each transmitter of the plurality of transmitters;
receive the communication signals transmitted from the plurality of transmitters;
receive the reflected data signals from the plurality of wireless communication devices; and
for each reflected data signal that is received;
determine the communication signal that was reflectively modulated to form the reflected data signal;
determine a time delay between receipt of the reflected data signal and receipt of the determined communication signal;
determine the spread spectrum code that was used to spread the determined communication signal, wherein the spread spectrum code is determined using the spread spectrum coding sequence stored in the receiver memory;
using the determined spread spectrum code, determine which of the plurality of transmitters transmitted the determined communication signal; and
determine an approximate location of the wireless communication device that formed the reflected data signal based on the determination of the transmitter that transmitted the determined communication signal, the determined time delay, and the stored information indicating the physical location of the transmitter that transmitted the determined communication signal.
1 Assignment
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Accused Products
Abstract
The present invention relates to a reflective communication system that allows information from wireless communication devices, such as radio-frequency identification devices (RFID), to be reflectively communicated to a receiver in lieu of using a separate communication system. A transmitter transmits a communication signal, having a carrier frequency, to the wireless communication device to provide power. The wireless communication device modulates a data signal onto the communication signal to form a reflected data signal. The wireless communication device reflects the reflected data signal directly to the receiver. In this manner, the process of communicating information from a wireless communication device is accomplished in one communication system rather than two. If the receiver also directly receives the communication signal from the transmitter, the receiver can determine the location of the wireless communication device relative to the transmitters.
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Citations
22 Claims
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1. A reflective communication system, comprising:
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a plurality of transmitters configured to operate on the same frequency, wherein each transmitter of the plurality of transmitters is physically separate from the rest of the plurality of transmitters, and wherein each transmitter of the plurality of transmitters is configured to transmit a communication signal that is spread with a spread spectrum code associated with the transmitter; a plurality of wireless communication devices located in the transmission field of the plurality of transmitters and configured to receive communication signals transmitted from the plurality of transmitters, wherein the plurality of wireless communication devices are further configured to reflectively modulate the communication signals with data signals having a modulation to form reflected data signals; and a receiver configured to; store, in a receiver memory, a spread spectrum coding sequence containing a plurality of receiver spread spectrum codes, wherein each receiver spread spectrum code correlates to a spread spectrum code respectively associated with a transmitter of the plurality of transmitters; store, in the receiver memory, information indicating a physical location of each transmitter of the plurality of transmitters; receive the communication signals transmitted from the plurality of transmitters; receive the reflected data signals from the plurality of wireless communication devices; and for each reflected data signal that is received; determine the communication signal that was reflectively modulated to form the reflected data signal; determine a time delay between receipt of the reflected data signal and receipt of the determined communication signal; determine the spread spectrum code that was used to spread the determined communication signal, wherein the spread spectrum code is determined using the spread spectrum coding sequence stored in the receiver memory; using the determined spread spectrum code, determine which of the plurality of transmitters transmitted the determined communication signal; and determine an approximate location of the wireless communication device that formed the reflected data signal based on the determination of the transmitter that transmitted the determined communication signal, the determined time delay, and the stored information indicating the physical location of the transmitter that transmitted the determined communication signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A reflective communication system, comprising:
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a plurality of transmitters, wherein each transmitter is configured to transmit a communication signal that is spread according to a different frequency-hopping sequence, wherein each transmitter of the plurality of transmitters is physically separate from the rest of the plurality of transmitters; a plurality of wireless communication devices located in the transmission field of the plurality of transmitters and configured to receive communication signals transmitted from the plurality of transmitters, wherein the plurality of wireless communication devices are further configured to reflectively modulate the communication signals with data signals having a modulation to form reflected data signals; and a receiver configured to; store, in a receiver memory, a plurality of frequency-hopping sequences, wherein each sequence is associated with one transmitter of the plurality of transmitters; store, in the receiver memory, information indicating a physical location of each transmitter of the plurality of transmitters; receive the communication signals from the plurality of transmitters; receive the reflected data signals from the plurality of wireless communication devices; and for each reflected data signal that is received; determine the communication signal that was reflectively modulated to form the reflected data signal; determine a time delay between receipt of the reflected data signal and receipt of the determined communication signal; determine the frequency-hopping sequence that was used to spread the determined communication signal, wherein the frequency-hopping sequence is determined using the plurality of frequency-hopping sequences stored in the receiver memory; determine, using the determined frequency-hopping sequence, which of the plurality of transmitters transmitted the determined communication signal; and determine an approximate location of the wireless communication device that formed the reflected data signal based on the determination of the transmitter that transmitted the determined communication signal, the determined time delay, and the stored information indicating the physical location of the transmitter that transmitted the determined communication signal. - View Dependent Claims (9, 10, 11, 12)
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13. A method of determining the origination of a data signal reflected by a wireless communication device that uses a communication signal from a transmitter as a communication medium, the method comprising:
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storing, in a memory, a spread spectrum coding sequence containing a plurality of receiver spread spectrum codes, wherein each receiver spread spectrum code correlates to a spread spectrum code that is respectively associated with a transmitter of a plurality of transmitters; storing, in the memory, information indicating a physical location of each transmitter of the plurality of transmitters; receiving communication signals that are transmitted on a same frequency from the plurality of transmitters, wherein each transmitted communication signal is spread with a different spread spectrum code, and wherein each transmitter of the plurality of transmitters is physically separate from the rest of the plurality of transmitters; receiving reflected data signals from a plurality of wireless communication devices, wherein the reflected data signals are formed by the wireless communication devices by reflectively modulating the communication signals with data signals; and for each reflected data signal that is received; determining the communication signal that was reflectively modulated to form the reflected data signal; determining a time delay between receipt of the reflected data signal and receipt of the determined communication signal; determining the spread spectrum code that was used to spread the determined communication signal, wherein the spread spectrum code is determined using the spread spectrum coding sequence stored in the receiver memory; using the determined spread spectrum code, determining which of the plurality of transmitters transmitted the determined communication signal; and determining an approximate location of the wireless communication device that formed the reflected data signal based on the determination of the transmitter that transmitted the determined communication signal, the determined time delay, and the stored information indicating the physical location of the transmitter that transmitted the determined communication signal. - View Dependent Claims (14, 15, 16, 17)
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18. A method of determining the origination of a data signal reflected by a wireless communication device that uses a communication signal from a transmitter as a communication medium, the method comprising:
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storing, in a memory, a plurality of frequency-hopping sequences, wherein each sequence is associated with one transmitter of a plurality of transmitters; storing, in the memory, information indicating a physical location of each transmitter of the plurality of transmitters; receiving, from a plurality of transmitters, communication signals that are spread according to different frequency-hopping sequences, wherein each transmitter from the plurality of transmitters is physically separate from the rest of the plurality of transmitters; receiving reflected data signals from a plurality of wireless communication devices, wherein the reflected data signals are formed by the wireless communication devices by reflectively modulating the communication signals with data signals; and for each reflected data signal that is received; determining the communication signal that was reflectively modulated to form the reflected data signal; determining a time delay between receipt of the reflected data signal and receipt of the determined communication signal; determining the frequency-hopping sequence that was used to spread the determined communication signal, wherein the frequency-hopping sequence is determined using the plurality of frequency-hopping sequences stored in the receiver memory; determining, using the determined frequency-hopping sequence, which of the plurality of transmitters originated the communication signal; and determining the approximate location of the wireless communication device that formed the reflected data signal based on the determination of the transmitter that originated the determined communication signal, the determined time delay, and the stored information indicating the physical location of the transmitter that originated the determined communication signal. - View Dependent Claims (19, 20, 21)
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22. A reflective communication system for determining the origination of a data signal reflected from a wireless communication device of a plurality of wireless communication devices that use communication signals from a plurality of transmitters as a communication medium, wherein each transmitter of the plurality of transmitters is physically separate from the rest of the plurality of transmitters, the system comprising:
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means for storing a spread spectrum coding sequence containing a plurality of receiver spread spectrum codes, wherein each receiver spread spectrum code correlates to a spread spectrum code respectively associated with a transmitter of the plurality of transmitters; means for storing information indicating a physical location of each transmitter of the plurality of transmitters; means for receiving communication signals transmitted from the plurality of transmitters; means for receiving reflected data signals that are reflectively transmitted by the plurality of wireless communication devices based on the communication signals transmitted from the plurality of transmitters; means for determining the communication signal that was reflectively modulated to form the reflected data signal for each reflected data signal that is received; means for determining a time delay between receipt of the reflected data signal and receipt of the determined communication signal for each reflected data signal that is received; means for determining the spread spectrum code that was used to spread each of the determined communication signals, wherein the spread spectrum code is determined using the stored spread spectrum coding sequence; means for determining which of the plurality of transmitters transmitted each of the determined communication signals using the respective determined spread spectrum code; and means for determining an approximate location of the wireless communication device based on the determination of each of the transmitters that transmitted the determined communication signals, the determined time delays, and the stored information indicating the physical location of the transmitters that transmitted the determined communication signals.
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Specification