# US 10,375,659 B1 · Wireless body-area network time synchronization using R peak reference broadcasts

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- Number: US 10,375,659 B1
- Document ID: US10375659B1
- Status: Granted
- Kind: B1
- Application number: 15/473,828
- Filed: 2017-03-30
- Granted: 2019-08-06
- Earliest claimed: 2016-04-25
- Assignees: The United States of America as represented by the Secretary of the Navy
- Applicants: SPAWAR Systems Center Pacific
- Inventors: Rohan Y. Ramlall
- Web page: https://patentgrep.com/patent/US10375659B1

## CPC

- H04W 56/0005: {synchronizing of arrival of multiple uplinks}
- H04B 13/005: {Transmission systems in which the medium consists of the human body}
- H04J 3/00: Time-division multiplex systems (H04J14/00 takes precedence; relay systems H04B7/14; selecting techniques H04Q)
- H04M 1/00: Substation equipment, e.g. for use by subscribers (subscriber services or facilities provided at exchanges H04M3/00; prepayment telephone coin boxes H04M17/00; current supply arrangements H04M19/08)
- H04W 4/06: Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
- H04W 4/38: for collecting sensor information
- H04W 4/70: Services for machine-to-machine communication [M2M] or machine type communication [MTC]
- H04L 67/12: specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
- Y02D 30/70: in wireless communication networks
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04B: TRANSMISSION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

A WBAN system for real-time telemonitoring health of a subject, involving a wearable biosignal sensors, each sensor of the sensors configured to measure a plurality of biosignals, ultra-low-power radios correspondingly coupled with the sensors; and a processor operable with at least one of the sensors and the radios, each radio of the radios configured to receive the biosignals from each corresponding sensor and to transmit the biosignals to a processor via a WBAN, and the processor configured to: receive the biosignals from the radios, process the biosignals via a set of executable instructions storable in relation to a nontransitory memory device, the set of executable instructions comprising an instruction for synchronizing time of the biosignals by using the broadcasted R peak reference, whereby real-time health data is providable, and transmit the real-time health data to a healthcare provider.

## Claims

### Claim 1

A WBAN system for real-time telemonitoring health of a subject, comprising:
an ECG sensor;
a plurality of wearable biosignal sensors comprising a plurality of ECG signals, the plurality of ECG signals providing ECG data, each sensor of the plurality of wearable biosignal sensors configured to measure a plurality of biosignals;
a plurality of ultra-low-power radios correspondingly coupled with the plurality of sensors; and
a processor operable with at least one of the plurality of sensors and the plurality of radios,
each radio of the plurality of radios configured to receive the plurality of biosignals from each corresponding sensor and to transmit the plurality of biosignals to a processor via a WBAN, and
the processor configured to: receive the plurality of biosignals from the plurality of radios, process the plurality of biosignals via a set of executable instructions storable in relation to a nontransitory memory device, the set of executable instructions comprising an instruction for synchronizing time of the plurality of biosignals by using the broadcasted R peak reference, whereby real-time health data is providable, and transmit the real-time health data to a healthcare provider;
wherein the set of executable instructions comprises an instruction for performing an RBS, and whereby a nondeterministic latency arising from at least one of a transmitting time delay and an accessing time delay is eliminated;
wherein the instruction for performing an RBS comprises an instruction for performing RB S by using a broadcast message corresponding to an R peak reference to synchronize each receiver of a set of receivers with one another, whereby each node in the set of receivers is configured to receive the same broadcast message, and whereby each node in the set of receivers respectively experiences a nondeterministic latency arising from only at least one of a propagation time delay and a receiving time delay;
wherein the processor is configured to operate via one of:
a first system architecture, wherein the ECG sensor is configured to transmit a short flag message every time that an R peak is detected, wherein the short flag message serves as a broadcast message to all devices, excluding the ECG sensor, in the WBAN, and wherein each receiving device records the time at which such device receives the short flag message; and
a second architecture, wherein the ECG sensor is configured to transmit an entire ECG data stream, wherein the entire ECG data stream serves as a broadcast message to all devices, excluding the ECG sensor, in the WBAN, and wherein each receiving device is configured to perform an R peak detection on the entire ECG data stream and to determine a time at which each R peak occurs, wherein each R peak serves as a notable timestamp point for at least its distinct shape and facile identification, and wherein a set of times at which each R peak occurs defines ti.

### Claim 2 (depends on 1)

The system of claim 1, wherein the broadcast message is transmittable to, and receivable by, one of a smartphone and any other device in the WBAN, wherein the broadcast message complies with at least one short-range, low-power, wireless, communication standard, wherein the at least one short-range, low-power, wireless, communication standard comprises at least one of IEEE 802.15.6 and Bluetooth®, whereby each device in the WBAN, excluding the ECG sensor, is configured to receive and process the broadcast message in an absence of additional hardware.

### Claim 3

A method of fabricating a WBAN system for real-time telemonitoring health of a subject, comprising:
providing a plurality of wearable biosignal sensors, each sensor of the plurality of sensors configured to measure a plurality of biosignals;
providing a plurality of ultra-low-power radios correspondingly coupled with the plurality of sensors;
providing a processor operable with at least one of the plurality of sensors and the plurality of radios,
providing the plurality of ultra-low-power radios comprising configuring each radio of the plurality of ultra-low-power radios to receive the plurality of biosignals from each corresponding sensor and to transmit the plurality of biosignals to the processor via a WBAN, wherein providing a plurality of ultra-low-power radios comprises providing the WBAN as a single-hop network, wherein any device in the WBAN is capable of directly communicating with any other device in the WBAN, wherein providing the WBAN as the single-hop network comprises providing the device as an ECG sensor, wherein the plurality of biosignals comprises a plurality of ECG signals, the plurality of ECG signals providing ECG data;
providing the processor comprising configuring the processor to: receive the plurality of biosignals from the plurality of radios, process the plurality of biosignals via a set of executable instructions storable in relation to a nontransitory memory device, the set of executable instructions comprising an instruction for synchronizing time of the plurality of biosignals by using the broadcasted R peak reference, whereby real-time health data is providable, and transmit the real-time health data to a healthcare provider,
wherein providing the processor comprises configuring the processor to operate via one of:
a first system architecture, wherein the ECG sensor is configured to transmit a short flag message every time that an R peak is detected, wherein the short flag message serves as a broadcast message to all devices, excluding the ECG sensor, in the WBAN, and wherein each receiving device records the time at which such device receives the short flag message; and
a second architecture, wherein the ECG sensor is configured to transmit an entire ECG data stream, wherein the entire ECG data stream serves as a broadcast message to all devices, excluding the ECG sensor, in the WBAN, and wherein each receiving device is configured to perform an R peak detection on the entire ECG data stream and to determine a time at which each R peak occurs, wherein each R peak serves as a notable timestamp point for at least its distinct shape and facile identification, and wherein a set of times at which each R peak occurs defines ti.

### Claim 4 (depends on 3)

The method of claim 3, wherein the broadcast message is transmittable to, and receivable by, one of a smartphone and any other device in the WBAN, wherein the broadcast message complies with at least one short-range, low-power, wireless, communication standard, wherein the at least one short-range, low-power, wireless, communication standard comprises at least one of IEEE 802.15.6 and Bluetooth®, whereby each device in the WBAN, excluding the ECG sensor, is configured to receive and process the broadcast message in an absence of additional hardware.

### Claim 5

A method of real-time telemonitoring health of a subject by way of a WBAN system, comprising:
providing the WBAN system, comprising:
providing a plurality of wearable biosignal sensors, each sensor of the plurality of sensors configured to measure a plurality of biosignals;
providing a plurality of ultra-low-power radios correspondingly coupled with the plurality of sensors; and
providing a processor operable with at least one of the plurality of sensors and the plurality of radios;
providing the plurality of ultra-low-power radios comprising configuring each radio of the plurality of ultra-low-power radios to receive the plurality of biosignals from each corresponding sensor and to transmit the plurality of biosignals to the processor via a WBAN, and
providing the processor comprising configuring the processor to: receive the plurality of biosignals from the plurality of radios, process the plurality of biosignals via a set of executable instructions storable in relation to a nontransitory memory device, the set of executable instructions comprising an instruction for synchronizing time of the plurality of biosignals by using the broadcasted R peak reference, whereby real-time health data is providable, and transmit the real-time health data to a healthcare provider;
performing RBS using a broadcast message, corresponding to an R peak reference, to synchronize each receiver of a set of receivers with one another, whereby each node in the set of receivers is configured to receive the same broadcast message, and whereby each node in the set of receivers respectively experiences only nondeterministic latencies from only propagation time delay and receiving time delay, wherein performing RBS comprises:
assuming that a set of receivers comprises two nodes, the two nodes comprising a first node and a second node, wherein tfirst node,A denotes a time that event A occurs with respect to a clock corresponding to the first node; broadcasting N distinct messages B to the first node and the second node via a transmitting node, wherein the first node and the second node respectively record a receive time for the N distinct messages B, and whereby respective timestamps tfirst node,B={tfirst node,B1, . . . , tfirst node,BN}T and tsecond node,B={tsecond node,B1, . . . , tsecond node,BN}T are generated;
exchanging respective timestamps tfirst node,B={tfirst node,B1, . . . , tfirst node,BN}T and tsecond node,B={tsecond node,B1, . . . , tsecond node,BN}T between the first node and the second node; and
performing a least-squares regression in relation to the node i, thereby determining a best linear fit for an expression y=mx+b, wherein y=tj−ti, x=ti, m=a clock skew, thereby determining a rate change of a difference in time between a node i clock and a node j clock, as measured in relation to the node i, and wherein b=a time difference between the node i clock and the node j clock at a time ti,B1, thereby enabling conversion of any timestamp from the node j clock to a timestamp which would have been generated by the node i clock, and thereby enabling conversion of any timestamp from the node i clock to a timestamp which would have been generated by the node j clock, whereby the two nodes of the set of receivers are synchronized with one another.

### Claim 6

A method of real-time telemonitoring health of a subject by way of a WBAN system, comprising:
providing the WBAN system, comprising:
providing a plurality of wearable biosignal sensors, each sensor of the plurality of sensors configured to measure a plurality of biosignals;
providing a plurality of ultra-low-power radios correspondingly coupled with the plurality of sensors; and
providing a processor operable with at least one of the plurality of sensors and the plurality of radios;
providing the plurality of ultra-low-power radios comprising configuring each radio of the plurality of ultra-low-power radios to receive the plurality of biosignals from each corresponding sensor and to transmit the plurality of biosignals to the processor via a WBAN, and
providing the processor comprising configuring the processor to: receive the plurality of biosignals from the plurality of radios, process the plurality of biosignals via a set of executable instructions storable in relation to a nontransitory memory device, the set of executable instructions comprising an instruction for synchronizing time of the plurality of biosignals by using the broadcasted R peak reference, whereby real-time health data is providable, and transmit the real-time health data to a healthcare provider;
performing RBS using a broadcast message, corresponding to an R peak reference, to synchronize each receiver of a set of receivers with one another, whereby each node in the set of receivers is configured to receive the same broadcast message, and whereby each node in the set of receivers respectively experiences only nondeterministic latencies from only propagation time delay and receiving time delay, wherein performing RBS comprises:
assuming that a set of receivers comprises two nodes, the two nodes comprising a first node and a second node, wherein tfirst node,A denotes a time that event A occurs with respect to a clock corresponding to the first node; broadcasting N distinct messages B to the first node and the second node via a transmitting node, wherein the first node and the second node respectively record a receive time for the N distinct messages B, and whereby respective timestamps tfirst node,B={tfirst node,B1, . . . , tfirst node,BN}T and tsecond node,B={tsecond node,B1, . . . , tsecond node,BN}T are generated;
exchanging respective timestamps tfirst node,B={tfirst node,B1, . . . , tfirst node,BN}T and tsecond node,B={tsecond node,B1, . . . , tsecond node,BN}T between the first node and the second node; and
performing Deming regression in relation to a node i, thereby determining a best linear fit for an expression y=mx+b, wherein y=tj−ti, x=ti, m=a clock skew, thereby determining a rate change of a difference in time between a node i clock and a node j clock, as measured in relation to the node i, and wherein b=the time difference between the node i clock and the node j clock at the time ti,B1, thereby enabling conversion of any timestamp from the node j clock to a timestamp which would have been generated by the node i clock, and thereby enabling conversion of any timestamp from the node i clock to a timestamp which would have been generated by the node j clock, whereby the two nodes of the set of receivers are synchronized with one another.