Zainar, Inc.

Philip A Kratz

Mainak M Chowdhury

Daniel M Jacker

Alexander Hooshmand

Jonathan Lu

Srdjan Miocinovic

Siamak Yousefi

Jonathan Shiao-en Lu

Alexander Feldman

Phillip B Hess

Tommi Ylamurto

Jonathan Shiao-En Lu

A method includes: based on a synchronization signal transmitted from a master node and received at a sniffer node, recording a partial channel state information characterizing a communication channel between the master node and the sniffer node for a second time period; in response to a localization signal transmitted from a target device, calculating a time bias between the master node and the sniffer node based on a transmit time of the synchronization signal, a third receive time of the synchronization signal at the sniffer node, a channel response characterizing the communication channel for a first time period, and the partial channel state information; and estimating a position of the target device based on a first receive time of the localization signal at the master node, a second receive time of the localization signal at the sniffer node, and the time bias.

Method for clock synchronization via differential channel state information

A method includes, generating a schedule for an asset tag group, the schedule defining: a multicast trigger time for transmission of a multicast trigger to the asset tag group; and for each asset tag in the asset tag group, a transmit time succeeding receipt of the multicast trigger and unique to the asset tag, and a wake window intersecting the transmit time and the receipt of the multiact trigger. The method also includes, at the node network: broadcasting the multicast trigger; and, at an asset tag in the asset tag group, entering a wake mode; receiving the multicast trigger; transmitting a ranging signal; and entering the sleep mode. The method further includes, at the node network: receiving ranging signals from the asset tag group; and deriving locations of the asset tags in the asset tag group based on the ranging signals received by the node network.

Methods for asset tag grouping and recovery

A method for calculating a time-of-arrival of a multicarrier uplink signal includes: accessing a multicarrier reference signal including a subcarrier reference signal for each subcarrier frequency in a set of subcarrier frequencies; receiving the multicarrier uplink signal transmitted from a user device, the multicarrier uplink signal including a subcarrier uplink signal for each subcarrier frequency in the set of subcarrier frequencies; for each subcarrier frequency in the set of subcarrier frequencies, calculating a phase difference, in a set of phase differences, between the subcarrier reference signal for the subcarrier frequency and a subcarrier uplink signal for the subcarrier frequency; calculating a time-of-arrival of the multicarrier uplink signal at the transceiver based on the set of adjusted phase differences; and transmitting the time-of-arrival of the multicarrier uplink signal to a remote server.

Systems and methods for multicarrier phase-based localization

A method includes: scheduling transmission of a first synchronization signal by a first node; and scheduling transmission of a second synchronization signal by a second node. The method also includes, after transmission of the first synchronization signal: receiving, from the first node, a first phase reference associated with the first synchronization signal; and receiving, from the second node, a first phase-of-arrival of the first synchronization signal at the second node. The method additionally includes, after transmission of the second synchronization signal: receiving, from the second node, a second phase reference associated with the second synchronization signal; and receiving, from the first node, a second phase-of-arrival of the second synchronization signal at the first node. The method further includes calculating a propagation delay between the first node and the second node based on the first phase reference, the second phase reference, the first phase-of-arrival, and the second phase-of-arrival.

Methods for time synchronization and localization in a mesh network

A method of determining a reference clock in a mesh network includes receiving multiple signals, correlating the multiple signals with a local signal generated by the first node to determine a coarse set of time differences, refining the coarse set of time differences using a phase of a carrier signal of the multiple signals to produce a refined set of time differences, and using the refined set of time differences to define a reference clock.

Method and system for radiolocation asset tracking via a mesh network

A method including accessing a network graph including: a set of transceiver nodes representing a set of transceivers operating in a mesh network of transceivers; a set of transmitter nodes representing a set of transmitters communicating with the mesh network of transceivers; and a set of edges, each connecting a pair of nodes in the set of nodes. The method also includes: identifying a subgraph of the network graph associated with a node in the set of nodes, the node representing a transceiver; accessing a network state of the subgraph comprising a set of edge values for each edge in the subgraph; calculating a probability of failure of the transceiver based on the network state of the subgraph; and in response to detecting the probability of failure of the transceiver exceeding a threshold likelihood, triggering a corrective action at the transceiver.

Method for identifying and diagnosing failures in pairwise time synchronization and frequency calibration in a mesh network

A radio-frequency system including: a self-complementary antenna characterized by an input impedance substantially independent of signal frequency across an operational frequency band; a passive coupling device characterized by a characteristic impedance and configured to couple the self-complementary antenna to a signal generator and a set of signal processors; a resistive matching network electrically connected between the self-complementary antenna and the passive coupling device configured to match the characteristic impedance of the passive coupling device to the input impedance of the self-complementary antenna; and a back-coupling line characterized by a substantially constant group delay across the operational frequency band configured to electromagnetically couple the signal generator to the set of signal processors.

Radio-frequency system characterized by flat group delay for radio-frequency time synchronization and ranging

A method includes, at a first node: transmitting a first calibration signal at a first time-of-departure measured by the first node; and transmitting a second calibration signal at a second time-of-departure measured by the first node. The method also includes, at a second node: receiving the first calibration signal at a first time-of-arrival measured by the second node; and receiving the second calibration signal at a second time-of-arrival measured by the second node. The method further includes: defining a first calibration point and a second calibration point in a set of calibration points, each calibration point comprising a time-of-departure and a time-of-arrival of each calibration signal; calculating a regression on the set of calibration points; and calculating a frequency offset between the first node and the second node based on the first regression.

Frequency and gain calibration for time synchronization in a network

A method including, at each node in each pair of nodes in a network: transmitting an outbound synchronization signal; generating a self-receive signal based on the outbound synchronization signal; detecting the self-receive signal at a self-receive TOA; detecting an inbound synchronization signal; based on the pair of self-receive TOAs and the pair of synchronization TOAs, for each pair of nodes in the network: calculating a pairwise time offset and distance; for each node in the network: based on the set of pairwise distances, calculating a location and a time bias of the node. The method also includes: at each node in the network, detecting a localization signal, transmitted by a device, at a localization TOA; and calculating a location of the device based on, for each node in the network, the localization signal detected at the node, and the time bias and the relative location of the node.

Method and system for radiofrequency localization of transmitting devices via a mesh network

A system for generating a self-receive signal includes: a signal generator; a first signal processor; a second signal processor; and an antenna. The system also includes a first passive coupling device: defining a first input port electromagnetically coupled to the signal generator; defining a first transmitted port; defining a first coupled port electromagnetically coupled to the first signal processor; and characterized by a first phase balance between the first transmitted port and the first coupled port. The system further includes a second passive coupling device: defining a second input port electromagnetically coupled to the antenna; defining a second transmitted port electromagnetically coupled to the first transmitted port; defining a second coupled port electromagnetically coupled to the second signal processor; and characterized by a second phase balance between the second transmitted port and the second coupled port substantially similar to the first phase balance.

System for generating accurate reference signals for time-of-arrival based time synchronization

A method for detecting times-of-arrival of signals comprising, at a receiving node: during a time slot, receiving a signal comprising a carrier signal characterized by a carrier frequency and modulated by a template signal defining a code sequence characterized by a transmitter chip period; demodulating the signal according to a local oscillator frequency to generate a received baseband signal, the local oscillator frequency and the carrier frequency defining a desynchronization ratio characterized by a denominator greater than a threshold denominator; sampling the received baseband signal at the transmitter chip period to generate a set of digital samples; generating a reconstructed baseband signal based on the set of digital samples; calculating a cross-correlation function comprising a cross-correlation of the reconstructed baseband signal and the template signal; and calculating, on the fine time grid, a time-of-arrival of the signal based on the cross-correlation function.

Method for precise timestamping of narrowband signals in the presence of multipath

A method includes, at a first node: transmitting a first synchronization signal at a first time according to a first clock of the first node; back-coupling the first synchronization signal to generate a first self-receive signal; calculating a time-of-arrival of the first self-receive signal according to the first clock; and calculating a time-of-arrival of the second synchronization signal according to the first clock. The method also includes, at the second node: transmitting the second synchronization signal at a second time according to a second clock of the second node; back-coupling the second synchronization signal to generate a second self-receive signal; calculating a time-of-arrival of the second self-receive signal according to the second clock; and calculating a time-of-arrival of the first synchronization signal according to the second clock. The method Sfurther includes calculating a time bias and a propagation delay between the pair of nodes based on the time-of-arrivals.

Methods for nanosecond-scale time synchronization over a network

A method includes, generating a schedule for an asset tag, the schedule defining: a unicast trigger time for transmission of a unicast trigger to the asset tag; a transmit time succeeding receipt of the multicast trigger; and a wake window intersecting the transmit time and the receipt of the multiact trigger. The method also includes transmitting the schedule from a node network to the asset tag and configuring the asset tag based on the schedule. The method also includes, at the node network, broadcasting the unicast trigger and, at an asset tag: entering a wake mode; receiving the unicast trigger; transmitting a ranging signal; and entering the sleep mode. The method further includes, at the node network: deriving location of the asset tag based on instance of the ranging signal received by nodes in the node network.

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Redwood City, CA, United States of America

Philip A Kratz