System and methods of radio interference based localization in sensor networks
First Claim
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1. A method for radio interference based sensor localization in a wireless sensor network, wherein the wireless sensor network has a plurality of spatially separated sensor nodes with each capable of transmitting and/or receiving a signal, comprising the steps of:
- a. selecting a first sensor node and a second sensor node as a pair of transmitters and each of the remaining sensor nodes as a receiver in the wireless sensor network, respectively;
b. transmitting a first signal and a second signal from the selected first sensor node and the selected second sensor node, respectively, to the wireless sensor network, wherein the first signal has a frequency, f1, and the second signal has a frequency, f2, the frequencies f1 and f2 being substantially close to each other such that a superposition of the first signal and the second signal in a position of space where a receiver is located results in an interference signal;
c. using the interference signal received by each of the receivers to estimate a phase offset of the received interference signal at the corresponding receiver, respectively;
d. obtaining a difference of the phase offsets of the interference signal for a pair of receivers;
e. calculating a distance range between the pair of transmitters and the corresponding pair of receivers from the obtained difference of phase offsets of the interference signal for the pair of receivers;
f. repeating steps (d) and (e) for the remaining receivers to obtain a set of the distance ranges; and
g. localizing relative positions of the plurality of spatially separated sensor nodes in the wireless sensor network from the set of the distance ranges,wherein the method further comprises the step of performing a frequency tuninci algorithm to determine a radio frequency setting for the pair of transmitters to transmit the first and second signals with a frequency difference substantially close to zero, and wherein performing the frequency tuning algorithm comprises the steps of;
(i) transmitting a first signal at a frequency varied at a fine-grain step and a second signal at a fixed frequency from a first and second transmitters of the pair of transmitters, respectively;
(ii) analyzing a frequency of the interference signal received by a receiver to determine the frequency of the first signal for which the frequency of the interference signal substantially close to zero, wherein the frequency of the interference signal is coincident with the frequency difference of the first signal and the second signal; and
(iii) propagating information of the analyzed frequency back to the first transmitter by the receiver, thereby causing the first transmitter to determine the radio frequency setting of the pair of transmitters for which the frequency of the interference signal is within a predetermined range.
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Abstract
A method for radio interference based sensor localization. In one embodiment, the method has the steps of creating an interference signal from a first transmitter and a second transmitter, measuring phase offsets of the interference signal received by a first receiver and a second receiver, respectively, and determining the locations of the first and second transmitters and the first and second receivers from the measured phase offsets.
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26 Claims
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1. A method for radio interference based sensor localization in a wireless sensor network, wherein the wireless sensor network has a plurality of spatially separated sensor nodes with each capable of transmitting and/or receiving a signal, comprising the steps of:
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a. selecting a first sensor node and a second sensor node as a pair of transmitters and each of the remaining sensor nodes as a receiver in the wireless sensor network, respectively; b. transmitting a first signal and a second signal from the selected first sensor node and the selected second sensor node, respectively, to the wireless sensor network, wherein the first signal has a frequency, f1, and the second signal has a frequency, f2, the frequencies f1 and f2 being substantially close to each other such that a superposition of the first signal and the second signal in a position of space where a receiver is located results in an interference signal; c. using the interference signal received by each of the receivers to estimate a phase offset of the received interference signal at the corresponding receiver, respectively; d. obtaining a difference of the phase offsets of the interference signal for a pair of receivers; e. calculating a distance range between the pair of transmitters and the corresponding pair of receivers from the obtained difference of phase offsets of the interference signal for the pair of receivers; f. repeating steps (d) and (e) for the remaining receivers to obtain a set of the distance ranges; and g. localizing relative positions of the plurality of spatially separated sensor nodes in the wireless sensor network from the set of the distance ranges, wherein the method further comprises the step of performing a frequency tuninci algorithm to determine a radio frequency setting for the pair of transmitters to transmit the first and second signals with a frequency difference substantially close to zero, and wherein performing the frequency tuning algorithm comprises the steps of; (i) transmitting a first signal at a frequency varied at a fine-grain step and a second signal at a fixed frequency from a first and second transmitters of the pair of transmitters, respectively; (ii) analyzing a frequency of the interference signal received by a receiver to determine the frequency of the first signal for which the frequency of the interference signal substantially close to zero, wherein the frequency of the interference signal is coincident with the frequency difference of the first signal and the second signal; and (iii) propagating information of the analyzed frequency back to the first transmitter by the receiver, thereby causing the first transmitter to determine the radio frequency setting of the pair of transmitters for which the frequency of the interference signal is within a predetermined range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for radio interference based sensor localization in a wireless sensor network, wherein the wireless sensor network has a plurality of spatially separated sensor nodes with each capable of transmitting and/or receiving a signal, comprising the steps of:
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a. selecting a pair of sensor nodes from a group of sensor nodes as a pair of transmitters and each of the remaining sensor nodes in the group of sensor nodes as a receiver, respectively, wherein the group of sensor nodes is selected from the wireless sensor network such that the sensor nodes in the group are located within a spatial range; b. scheduling transmission times for the pair of transmitters to transmit a pair of signals, wherein the pair of signals create an interference signal in a position of space where a receiver is located, and wherein the interference signal has an interference range coincident with the spatial range; c. calibrating the pair of transmitters to simultaneously transmit the pair of signals at frequencies within a radio frequency setting at the scheduled transmission times, wherein the frequencies of the pair of signals vary according to a fine-grain step at different transmission times; d. transmitting the pair of signals at the frequencies from the pair of transmitters at the scheduled transmission times; e. analyzing received signal strength indicator (RSSI) samples of the interference signal at each of the receivers so as to estimate the frequency and phase offset of the interference signal, respectively; f. obtaining a difference of the phase offsets of the interference signal for a pair of receivers; g. calculating a distance range between the pair of transmitters and the pair of receivers from the obtained difference of phase offsets of the interference signal for each pair of receivers to obtain a set of the distance ranges; and h. localizing relative positions of the group of sensor nodes in the wireless sensor network from the set of the distance ranges, wherein the calibrating step is performed with a frequency tuning algorithm, and wherein performing the frequency tuning algorithm comprises the steps of; (i) transmitting a first signal at a frequency varied at a fine-grain step and a second signal at a fixed frequency from a first and second transmitters of the pair of transmitters, respectively; (ii) analyzing a frequency of the interference signal received by a receiver to determine the frequency of the first signal for which the frequency of the interference signal substantially close to zero, wherein the frequency of the interference signal is coincident with the frequency difference of the first signal and the second signal; and (iii) propagating information of the analyzed frequency back to the first transmitter by the receiver, thereby causing the first transmitter to determine the radio frequency setting of the pair of transmitters for which the frequency of the interference signal is within a predetermined range. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A system for radio interference based sensor localization, comprising:
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a. a sensor network having a number, N, of spatially separated sensor nodes, N being an integer, wherein the number N of spatially separated sensor nodes have a first transmitter node and a second transmitter node for transmitting a first signal and a second signal, respectively, to the sensor network, and (N-2) receiver nodes, wherein the first signal has a frequency, f1, and the second signal has a frequency, f2, the frequencies f1 and f2 being substantially close to each other such that a superposition of the first signal and the second signal in a position of space where a receiver node is located results in an interference signal; and
b. a base station for communicating with the number N of spatially separated sensor nodes in the sensor network and processing information received from the number N of spatially separated sensor nodes so as to localize the number N of spatially separated sensor nodes,wherein the number N of spatially separated sensor nodes communicate to each other wirelessly, wherein each of the number N of spatially separated sensor nodes comprises a radio chip, and wherein the radio chip is capable of transmitting a radio frequency signal in a predetermined frequency band at different power levels. frequency signal in a predetermined frequency band at different power levels. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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Specification