The present application is related to and claims priority from the following U.S. patent applications:
The authentication of signals is a paramount factor in ensuring trusted communications. Filtering out inauthentic signals allows for overcoming noise (e.g., inadvertent multi-path reflected signals) and adversarial attacks. For example, adversarial nodes may transmit spoofed signals configured to imitate other nodes and/or transmit signals configured as Denial of Service attacks. Filtering out inauthentic signals may be limited using conventional methods. For example, electronically scanned arrays may be required for angle of arrival-based authentication of GNSS signals using conventional techniques, but these techniques may be susceptible to nodes overhead generating similar angles of arrival. Note that this is only one limitation of many possible limitations of various techniques of conventional authentication systems.
Consequently, there is a need for a system and method that can address these issues.
A system is disclosed in accordance with one or more illustrative embodiments of the present disclosure. In one illustrative embodiment, the system may include a receiver or transmitter node. In another illustrative embodiment, the receiver or transmitter node may include a communications interface with an antenna element and a controller. In another illustrative embodiment, the controller may include one or more processors and have information of own node velocity and own node orientation relative to a common reference frame. In another illustrative embodiment, the receiver or transmitter node may be time synchronized to apply Doppler corrections to signals, the Doppler corrections associated with the receiver or transmitter node's own motions relative to the common reference frame, the Doppler corrections applied using Doppler null steering along Null directions. In another illustrative embodiment, the receiver node is configured to determine a parameter of the signals based on Doppler null steering. In another illustrative embodiment, the receiver node is configured to determine an authenticity of the signals based on the parameter.
This Summary is provided solely as an introduction to subject matter that is fully described in the Detailed Description and Drawings. The Summary should not be considered to describe essential features nor be used to determine the scope of the Claims. Moreover, it is to be understood that both the foregoing Summary and the following Detailed Description are example and explanatory only and are not necessarily restrictive of the subject matter claimed.
The detailed description is described with reference to the accompanying figures. The use of the same reference numbers in different instances in the description and the figures may indicate similar or identical items. Various embodiments or examples (“examples”) of the present disclosure are disclosed in the following detailed description and the accompanying drawings. The drawings are not necessarily to scale. In general, operations of disclosed processes may be performed in an arbitrary order, unless otherwise provided in the claims.
Before explaining one or more embodiments of the disclosure in detail, it is to be understood that the embodiments are not limited in their application to the details of construction and the arrangement of the components or steps or methodologies set forth in the following description or illustrated in the drawings. In the following detailed description of embodiments, numerous specific details may be set forth in order to provide a more thorough understanding of the disclosure. However, it will be apparent to one of ordinary skill in the art having the benefit of the instant disclosure that the embodiments disclosed herein may be practiced without some of these specific details. In other instances, well-known features may not be described in detail to avoid unnecessarily complicating the instant disclosure.
As used herein a letter following a reference numeral is intended to reference an embodiment of the feature or element that may be similar, but not necessarily identical, to a previously described element or feature bearing the same reference numeral (e.g., 1, 1a, 1b). Such shorthand notations are used for purposes of convenience only and should not be construed to limit the disclosure in any way unless expressly stated to the contrary.
Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
In addition, use of “a” or “an” may be employed to describe elements and components of embodiments disclosed herein. This is done merely for convenience and “a” and “an” are intended to include “one” or “at least one,” and the singular also includes the plural unless it is obvious that it is meant otherwise.
Finally, as used herein any reference to “one embodiment”, “in embodiments” or “some embodiments” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment disclosed herein. The appearances of the phrase “in some embodiments” in various places in the specification are not necessarily all referring to the same embodiment, and embodiments may include one or more of the features expressly described or inherently present herein, or any combination or sub-combination of two or more such features, along with any other features which may not necessarily be expressly described or inherently present in the instant disclosure.
Broadly speaking, embodiments herein are directed to systems and methods for determining parameters of signals based on Doppler nulling (e.g., relative positions of nodes) to authenticate signals.
As described in U.S. patent application Ser. No. 18/130,285, filed Apr. 3, 2023, which is herein incorporated by reference in its entirety, embodiments may utilize time synchronized scanning sequences (along with directionality) to improve metrics such as signal-to-noise ratio, signal acquisition time, speed of attaining situational awareness of attributes of surrounding nodes, range, and the like. In some embodiments, a zero value or near zero value (e.g., or the like such as a zero crossing) of a calculated net frequency shift of a received signal is used to determine a bearing angle between the source (e.g., Tx node) and the receiving node using a time-of-arrival of the received signal.
It is noted that U.S. patent application Ser. No. 17/857,920, filed Jul. 5, 2022, is at least partially reproduced by at least some (or all) of the illustrations of
Moreover, and stated for purposes of navigating the disclosure only and not to be construed as limiting, descriptions that may relate to other language not necessarily reproduced from U.S. patent application Ser. No. 17/857,920 include the discussion and figures after
Referring now to
Some embodiments may use analysis performed in a common reference frame (e.g., a common inertial reference frame, such as the Earth, which may ignore the curvature of Earth), and it is assumed that the communications system for each of the transmitter and receiver is informed by the platform of its own velocity and orientation. The approach described herein can be used for discovery and tracking, but the discussion here focuses on discovery which is often the most challenging aspect.
The meaning of the ‘Doppler Null’ can be explained in part through a review of the two-dimensional (2D) case without the receiver motion, and then may be expounded on by a review of adding the receiver motion to the 2D case, and then including receiver motion in the 3D case.
The Doppler frequency shift of a communications signal is proportional to the radial velocity between transmitter and receiver, and any significant Doppler shift is typically a hindrance that should be considered by system designers. In contrast, some embodiments utilize the Doppler effect to discriminate between directions with the resolution dictated by selected design parameters. Furthermore, such embodiments use the profile of the net frequency shift as the predetermined ‘Null’ direction scans through the angle space. The resultant profile is sinusoidal with an amplitude that provides the transmitter's speed, a zero net frequency shift when the ‘Null’ direction aligns with the receiver, and a minimum indicating the direction of the transmitter's velocity. It should be noted that that the transmitter cannot correct for Doppler in all directions at one time so signal characteristics are different in each direction and are different for different transmitter velocities as well. It is exactly these characteristics that the receiver uses to determine spatial awareness. The received signal has temporal spatial characteristics that can be mapped to the transmitter's direction and velocity. This approach utilizes the concept of a ‘Null’ which is simply the direction where the transmitter perfectly corrects for its own Doppler shift. The same ‘Nulling’ protocol runs on each node and scans through all directions, such as via a scanning sequence of a protocol. Here we arbitrarily illustrate the scanning with discrete successive steps of 10 degrees but in a real system; however, it should be understood that any suitable step size of degrees may be used for Doppler null scanning.
As already mentioned, one of the contributions of some embodiments is passive spatial awareness. Traditionally, spatial information for neighbor nodes (based on a global positioning system (GPS) and/or gyros and accelerometers) can be learned via data communication. Unfortunately, spatial awareness via data communication, referred to as active spatial awareness is possible only after communication has already been established, not while discovering those neighbor nodes. Data communication is only possible after the signals for neighbor nodes have been discovered, synchronized and Doppler corrected. In contrast, in some embodiments, the passive spatial awareness described herein may be performed using only synchronization bits associated with acquisition. This process can be viewed as physical layer overhead and typically requires much lower bandwidth compared to explicit data transfers. The physical layer overheads for discovery, synchronization and Doppler correction have never been utilized for topology learning for upper layers previously.
Traditionally, network topology is harvested via a series of data packet exchanges (e.g., hello messaging and link status advertisements). The passive spatial awareness may eliminate hello messaging completely and provide a wider local topology which is beyond the coverage of hello messaging. By utilizing passive spatial awareness, highly efficient mobile networking is possible. Embodiments may improve the functioning of a network, itself.
Referring to
In embodiments, the multi-node communications network 100 may include any multi-node communications network known in the art. For example, the multi-node communications network 100 may include a mobile network in which the Tx and Rx nodes 102, 104 (as well as every other communications node within the multi-node communications network) is able to move freely and independently. Similarly, the Tx and Rx nodes 102, 104 may include any communications node known in the art which may be communicatively coupled. In this regard, the Tx and Rx nodes 102, 104 may include any communications node known in the art for transmitting/transceiving data packets. For example, the Tx and Rx nodes 102, 104 may include, but are not limited to, radios (such as on a vehicle or on a person), mobile phones, smart phones, tablets, smart watches, laptops, and the like. In embodiments, the Rx node 104 of the multi-node communications network 100 may each include, but are not limited to, a respective controller 106 (e.g., control processor), memory 108, communication interface 110, and antenna elements 112. (In embodiments, all attributes, capabilities, etc. of the Rx node 104 described below may similarly apply to the Tx node 102, and to any other communication node of the multi-node communication network 100.)
In embodiments, the controller 106 provides processing functionality for at least the Rx node 104 and can include any number of processors, micro-controllers, circuitry, field programmable gate array (FPGA) or other processing systems, and resident or external memory for storing data, executable code, and other information accessed or generated by the Rx node 104. The controller 106 can execute one or more software programs embodied in a non-transitory computer readable medium (e.g., memory 108) that implement techniques described herein. The controller 106 is not limited by the materials from which it is formed or the processing mechanisms employed therein and, as such, can be implemented via semiconductor(s) and/or transistors (e.g., using electronic integrated circuit (IC) components), and so forth.
In embodiments, the memory 108 can be an example of tangible, computer-readable storage medium that provides storage functionality to store various data and/or program code associated with operation of the Rx node 104 and/or controller 106, such as software programs and/or code segments, or other data to instruct the controller 106, and possibly other components of the Rx node 104, to perform the functionality described herein. Thus, the memory 108 can store data, such as a program of instructions for operating the Rx node 104, including its components (e.g., controller 106, communication interface 110, antenna elements 112, etc.), and so forth. It should be noted that while a single memory 108 is described, a wide variety of types and combinations of memory (e.g., tangible, non-transitory memory) can be employed. The memory 108 can be integral with the controller 106, can comprise stand-alone memory, or can be a combination of both. Some examples of the memory 108 can include removable and non-removable memory components, such as random-access memory (RAM), read-only memory (ROM), flash memory (e.g., a secure digital (SD) memory card, a mini-SD memory card, and/or a micro-SD memory card), solid-state drive (SSD) memory, magnetic memory, optical memory, universal serial bus (USB) memory devices, hard disk memory, external memory, and so forth.
In embodiments, the communication interface 110 can be operatively configured to communicate with components of the Rx node 104. For example, the communication interface 110 can be configured to retrieve data from the controller 106 or other devices (e.g., the Tx node 102 and/or other nodes), transmit data for storage in the memory 108, retrieve data from storage in the memory, and so forth. The communication interface 110 can also be communicatively coupled with the controller 106 to facilitate data transfer between components of the Rx node 104 and the controller 106. It should be noted that while the communication interface 110 is described as a component of the Rx node 104, one or more components of the communication interface 110 can be implemented as external components communicatively coupled to the Rx node 104 via a wired and/or wireless connection. The Rx node 104 can also include and/or connect to one or more input/output (I/O) devices. In embodiments, the communication interface 110 includes or is coupled to a transmitter, receiver, transceiver, physical connection interface, or any combination thereof.
It is contemplated herein that the communication interface 110 of the Rx node 104 may be configured to communicatively couple to additional communication interfaces 110 of additional communications nodes (e.g., the Tx node 102) of the multi-node communications network 100 using any wireless communication techniques known in the art including, but not limited to, GSM, GPRS, CDMA, EV-DO, EDGE, WiMAX, 3G, 4G, 4G LTE, 5G, WiFi protocols, RF, LoRa, and the like.
In embodiments, the antenna elements 112 may include directional or omnidirectional antenna elements capable of being steered or otherwise directed (e.g., via the communications interface 110) for spatial scanning in a full 360-degree arc (114) relative to the Rx node 104 (or even less than a full 360 degree arc).
In embodiments, the Tx node 102 and Rx node 104 may one or both be moving in an arbitrary direction at an arbitrary speed, and may similarly be moving relative to each other. For example, the Tx node 102 may be moving relative to the Rx node 104 according to a velocity vector 116, at a relative velocity VTx and a relative angular direction (an angle α relative to an arbitrary direction 118 (e.g., due east); θ may be the angular direction of the Rx node relative to due east.
In embodiments, the Tx node 102 may implement a Doppler nulling protocol. For example, the Tx node 102 may adjust its transmit frequency to counter the Doppler frequency offset such that there is no net frequency offset (e.g., “Doppler null”) in a Doppler nulling direction 120 (e.g., at an angle ϕ relative to the arbitrary direction 118). The transmitting waveform (e.g., the communications interface 110 of the Tx node 102) may be informed by the platform (e.g., the controller 106) of its velocity vector and orientation (e.g., α, VT) and may adjust its transmitting frequency to remove the Doppler frequency shift at each Doppler nulling direction 120 and angle ϕ.
To illustrate aspects of some embodiments, we show the 2D dependence of the net frequency shift for a stationary receiver as a function of Null direction across the horizon, as shown in a top-down view of
The Doppler shift is a physical phenomenon due to motion and can be considered as a channel effect. In this example the transmitter node 102 is the only moving object, so it is the only source of Doppler shift. The Doppler frequency shift as seen by the receiver node 104 due to the transmitter node 102 motion is:
where c is the speed of light
The other factor is the transmitter frequency adjustment term that should exactly compensate the Doppler shift when the ‘Null’ direction aligns with the receiver direction. It is the job of the transmitter node 102 to adjust its transmit frequency according to its own speed (|{right arrow over (VT)}|), and velocity direction (α). That transmitter frequency adjustment (ΔfT) is proportional to the velocity projection onto the ‘Null’ direction (ϕ) and is:
The net frequency shift seen by the receiver is the sum of the two terms:
It is assumed that the velocity vector and the direction changes slowly compared to the periodic measurement of Δfnet. Under those conditions, the unknown parameters (from the perspective of the receiver node 104) of α, |{right arrow over (VT)}|, and θ are constants.
Furthermore, it is assumed that the receiver node 104 has an implementation that resolves the frequency of the incoming signal, as would be understood to one of ordinary skill in the art.
From the profile, the receiver node 104 can therefore determine the transmitter node's 102 speed, the transmitter node's 102 heading, and the direction of the transmitter node 102 is known to at most, one of two locations (since some profiles have two zero crossings). It should be noted that the two curves cross the y axis twice (0 & 180 degrees in
Referring to
The simultaneous movement scenario is depicted in
Again, the Doppler shift is a physical phenomenon due to motion and can be considered as a channel effect, but in this case both the transmitter node 102 and the receiver node 104 are moving so there are two Doppler shift terms. The true Doppler shift as seen by the receiver due to the relative radial velocity is:
The other factors are the transmitter node 102 and receiver node 104 frequency adjustment terms that exactly compensates the Doppler shift when the ‘Null’ direction aligns with the receiver direction. It is the job of the transmitter node 102 to adjust the transmitter node's 102 transmit frequency according to its own speed (|{right arrow over (VT)}|), and velocity direction (α). That transmitter node frequency adjustment is proportional to the velocity projection onto the ‘Null’ direction (ϕ) and is the first term in the equation below.
It is the job of the receiver node 104 to adjust the receiver node frequency according to the receiver node's 104 own speed (|{right arrow over (VR)}|), and velocity direction (β). That receiver node frequency adjustment is proportional to the velocity projection onto the ‘Null’ direction (ϕ) and is the second term in the equation below. The receiver node frequency adjustment can be done to the receive signal prior to the frequency resolving algorithm or could be done within the algorithm.
The net frequency shift seen by the receiver is the sum of all terms:
Again, it is assumed that the receiver node 104 has an implementation that resolves the frequency of the incoming signal, as would be understood in the art.
Also, it is assumed that the velocity vector and direction changes slowly compared to the periodic measurement of Δfnet. Again, under such conditions, the unknown parameters (from the perspective of the receiver node 104) α, |{right arrow over (VT)}|, and θ are constants. When the velocity vector or direction change faster, then this change could be tracked, for example if the change is due to slow changes in acceleration.
The net frequency shift for the two-dimensional (2D) moving receiver node 104 approach is shown in
Again, there is an initial dual point ambiguity with the position, θ, but the transmitter node's 102 speed and velocity vector is known.
Referring now to
The number of sets to span the space is shown in
Referring now to
The 3D approach to Doppler nulling follows the 2D approach but it is illustrated here with angles and computed vectorially for simplicity.
In three dimensions, it is convenient to express the equations in vector form which is valid for 2 or 3 dimensions.
The true Doppler shift as seen by the receiver node 104 due to the relative radial velocity which is the projection onto the vector:
The nulling protocol adjusts the transmit node frequency and receiver node frequency due to their velocity projections onto the direction
The net frequency shift seen by the receiver node 104 is the sum of all terms:
The net frequency shift for the 3D moving receiver node 104 approach is not easy to show pictorially but can be inspected with mathematical equations to arrive at useful conclusions. The first two terms are the Doppler correction (DC) offset and the last two terms are the null dependent terms. Since the is the independent variable, the maximum occurs when ({right arrow over (VR)}−{right arrow over (VT)}) and are parallel and is a minimum when they are antiparallel. Furthermore, the relative speed is determined by the amplitude,
Lastly, the net frequency is zero when the is parallel (i.e., parallel in same direction, as opposed to anti-parallel) to .
For the 3D case:
Referring still to
In some embodiments, the applying of the Doppler corrections associated with the receiver node's own motions relative to the common reference frame is based on a common reference frequency. For example, a common reference frequency may be adjusted by a node's own motions to cancel out those motions in reference to the null angle. This common reference frequency may be known by each node prior to transmission and/or reception of the signals. In some embodiments, calculating the net frequency change seen by the receiver node 104 is based on the common reference frequency. For example, the net frequency change may be a difference between a measured frequency of the signals and the common reference frequency.
For purposes of discussing the receiver node 104, a “source” generally refers to a source of a received signal, multiple sources of multiple signals, a single source of multiple signals, and/or the like. For example, a source may be a transmitter node 102 configured to apply Doppler corrections as disclosed herein and in applications from which priority is claimed and/or incorporated by reference. In this regard, a receiver node 104 may determine one or more attributes of the source (e.g., bearing between the receiver node 104 and the source, bearing of the velocity of the source, amplitude/speed of the velocity, range, and the like). In some embodiments, the receiver node 104 and the source (e.g., transmitter node 102) are configured to use a same, compatible, and/or similar Doppler correction, protocol, common reference frame, common reference frequency, time synchronization, and/or the like such that the receiver node 104 may determine various attributes of the source. Note, in some embodiments, that one or more of these may be known ahead of time, be determined thereafter, included as fixed variable values as part of the protocol, and/or determined dynamically (in real time) as part of the protocol. For example, the protocol may determine that certain common reference frames should be used in certain environments, such as using GPS coordinates on land and a naval ship beacon transmitter common reference frame location (which may be mobile) over certain areas of ocean, which may dynamically change in real time as a location of a node changes.
In some embodiments, the transmitter node 102 and the receiver node 104 are time synchronized via synchronization bits associated with acquisition. For example, the synchronization bits may operate as physical layer overhead.
In some embodiments, the transmitter node 102 is configured to adjust a transmit frequency according to an own speed and an own velocity direction of the transmitter node 102 so as to perform a transmitter-side Doppler correction. In some embodiments, the receiver node 104 is configured to adjust a receiver frequency of the receiver node 104 according to an own speed and an own velocity direction of the receiver node 104 so as to perform a receiver-side Doppler correction. In some embodiments, an amount of adjustment of the adjusted transmit frequency is proportional to a transmitter node 102 velocity projection onto a Doppler null direction, wherein an amount of adjustment of the adjusted receiver frequency is proportional to a receiver node 104 velocity projection onto the Doppler null direction. In some embodiments, the receiver node 102 is configured to determine a relative speed between the transmitter node 102 and the receiver node 104. In some embodiments, the receiver node 104 is configured to determine a direction that the transmitter node 102 is in motion and a velocity vector of the transmitter node 102. In some embodiments, a maximum net frequency shift for a Doppler correction by the receiver node 104 occurs when a resultant vector is parallel to the Doppler null direction, wherein the resultant vector is equal to a velocity vector of the receiver node 104 minus the velocity vector of the transmitter node 102. In some embodiments, a minimum net frequency shift for a Doppler correction by the receiver node 104 occurs when a resultant vector is antiparallel to the Doppler null direction, wherein the resultant vector is equal to a velocity vector of the receiver node 104 minus the velocity vector of the transmitter node 102. In some embodiments, a net frequency shift for a Doppler correction by the receiver node 104 is zero when a vector pointing to the receiver node from the transmitter node 102 is parallel to the Doppler null direction.
Referring now to
A step 702 may include providing a transmitter node and a receiver node, wherein each node of the transmitter node and the receiver node are time synchronized, wherein each node of the transmitter node and the receiver node are in motion, wherein each node of the transmitter node and the receiver node comprises a communications interface including at least one antenna element, wherein each node of the transmitter node and the receiver node further comprises a controller operatively coupled to the communications interface, the controller including one or more processors, wherein the controller has information of own node velocity and own node orientation.
A step 704 may include based at least on the time synchronization, applying, by the transmitter node, Doppler corrections to the transmitter node's own motions relative to a common reference frame.
A step 706 may include based at least on the time synchronization, applying, by the receiver node, Doppler corrections to the receiver node's own motions relative to the common reference frame, wherein the common reference frame is known to the transmitter node and the receiver node prior to the transmitter node transmitting signals to the receiver node and prior to the receiver node receiving the signals from the transmitter node.
Further, the method 700 may include any of the operations disclosed throughout.
The null scanning/steering technique discussed herein illustrates a system and a method for spatial awareness from resolving the temporal spatial characteristics of the transmitter node's 102 radiation. This approach informs the receiver node 104 of the relative speed between the transmitter node 102 and receiver node 104 as well as the transmitter node direction and transmitter node velocity vector. This approach includes scanning through all directions and has a high sensitivity (e.g., low net frequency shift) when the null direction is aligned with the transmitter node direction. This approach can be implemented on a highly sensitive acquisition frame which is typically much more sensitive than explicit data transfers which allow for the ultra-sensitive spatial awareness with relatively low power.
This sentence may mark an end to the (at least partially) reproduced language from U.S. patent application Ser. No. 17/857,920 corresponding to the (at least partially) reproduced
Broadly speaking, embodiments herein are directed to systems and methods for determining parameters (e.g., time of arrival, frequency, and the like) of signals based on Doppler nulling and using such parameters to authenticate the signals.
Embodiments of the present disclosure may extend doppler nulling for use in signal authentication. For example, Doppler nulling-based techniques such as those disclosed herein may be used to track signals consistent with a platform (e.g., node) moving in space and time. Then, once an explicit data transfer link is established with the node based on the tracked signals, the arrival time and/or frequency offset of (future) signals may be used to determine whether such signals are authentic or inauthentic (e.g., noise and/or adversarial signals coming from a different undesired node). In this way, it is contemplated that Doppler nulling signals may allow for low susceptibility to spoofing and/or Denial of Service attacks.
In some embodiments, DNS or any other concept disclosed herein may be utilized for spoofing detection, to augment spoofing detection, and/or in lieu of other spoofing detection techniques. For example, system 100 may be configured for spectrum analysis (SA) and/or authenticating position, navigation, and timing (PNT) information.
Doppler null scanning (DNS) (i.e., Doppler null steering) may be used to as a link acquisition framework that characterizes each neighbor link's parameters. Two important parameters are the arrival time and frequency offset. Time of arrival is a combination of propagation time and clock time differences and may assume knowledge of neighbor signal transmit times. Frequency offset is a combination of Doppler shift and clock frequency errors.
In embodiments, the DNS link acquisition framework discovers and tracks DNS signals that have spatial-temporal characteristics consistent with a platform moving in space and time. Reflected signals (e.g., multipath or repeaters) in general do not have consistent characteristics and the inconsistencies can be measured to indicate inauthentic path (e.g., spoofing, multipath). In embodiments, once DNS establishes a link, explicit data transfers can utilize the arrival time and frequency offset information and only process signals that match those characteristics resulting in low susceptibility to spoofing and low susceptibility to Denial of Service attacks.
Embodiments may be used in many commercial and civilian applications such as, but not necessarily limited to, filtering out inauthentic undesired noise (e.g., multi-path reflected signals, background RF noise), and/or filtering out adversarial nodes (e.g., WiFi spoofing configured to intercept and/or inject adversarial explicit data packets to and from nodes). Applications may also include military applications such as spoofing and Denial of Service attacks on military communications.
Examples of doppler nulling methods include, but are not limited to, methods and other descriptions (e.g., at least some theory and mathematical basis) are disclosed in U.S. patent application Ser. No. 17/233,107, filed Apr. 16, 2021, which is hereby incorporated by reference in its entirety; U.S. patent application Ser. No. 17/534,061, filed Nov. 23, 2021, which is hereby incorporated by reference in its entirety; and U.S. patent application Ser. No. 17/857,920, filed Jul. 5, 2022, which is hereby incorporated by reference in its entirety. In embodiments, doppler nulling methods allow for benefits such as, but not limited to, relatively quickly and/or efficiently detecting transmitter nodes and determining transmitter node attributes (e.g., transmitter node speed, transmitter node bearing, relative bearing of transmitter node relative to receiver node, relative distance of transmitter node relative to receiver node, and the like).
For purposes of
In some embodiments, the receiver node 104 is configured to determine a parameter of the signals 802 based on the signals 802 based on the Doppler null steering. For example, the receiver node 104 may be configured to determine a relative position (e.g., bearing angle 804 and range 806) of the transmitter node 102 based on Doppler null steering as disclosed herein. For instance, the relative position may be determined via scanning sequence protocols time synced such that the time of arrival of a signal 802 of a scanning sequence may be used to determine the bearing angle 804 from which the signal 802 was sent due to when (e.g., in which time slot) in the scanning sequence it was sent. For instance, at time 0 of the scanning sequence known to both nodes 102, 104, the transmitter node may transmit a pulse of the signal 802 at a transmission angle (e.g., any angle such as East; about 135 degrees clockwise from East as shown; and/or the like) corresponding to a bearing angle 804 (e.g., 45 degrees as shown). With time margin padding between pulses longer than the maximum transmission time of the signal based on a maximum transmission range, the receiver node 104 may determine at which transmission angle, and therefore which bearing angle 804, the signal 802 came from (or should have come from if authentic).
In such a scenario, it is contemplated that due to the laws of physics, discrepancies caused by an inability to spoof all parameters of a Doppler nulling signal in all directions, limits of spatial knowledge obtainable by an adversarial node, and/or the like, that inauthentic signals (e.g., see actual signal 904, 906 spoofed as inauthentic signal 822 in
First, consider that a source (e.g., node 902) of an inauthentic signal 822 likely wouldn't be time synchronized with the receiver node 104 to match an expected time of arrival corresponding to an expected range (e.g., range 826 in
Further, even if an adversarial node had perfect spatial awareness knowledge of nodes 102, 104 and was time synchronized to mimic the time of arrival of the particular bearing angle 804 and range 826 according to a Doppler nulling scanning sequence (if such spoofing is even possible), the actual bearing angle (not labeled) of the real signal 904 would likely not match the spoofed bearing angle 824, and could therefore be used to determine the signal 822 is inauthentic. For instance, even if the time of arrival of the real signal 904 is spoofed/delayed to match the time of arrival of signal 822, the amplitude peak of the signal 904 determined via an electronically scanned antenna (ESA) of the receiver node 104 may correspond to an inauthentic bearing angle of real signal 904.
Further, in some embodiments, uncorroborated parameters (e.g., differences in spoofed source location) may be used to determine a signal 822, 1022 is inauthentic. For example, any parameter of a signal received by receiver node 104 may be compared to the same signal received by a second receiver node 910 to determine an authenticity/inauthenticity of the signal. For instance, as shown in
In some embodiments, the receiver node 104 is configured to determine a parameter of the signals 802, such as signals based on the Doppler nulling as disclosed herein. For instance, the time of arrival of a signal may correspond to a bearing angle 804 according to a scanning/steering sequence configured to correspond to scanning a null angle at incremental nulling angles (e.g., every 10 degrees) repeatedly. Therefore, each time slot may correspond to receiving a signal from a transmission angle that corresponds to an inverse (e.g., 180 degrees from) the bearing angle 804. Further, a more precise analysis of the exact time of arrival of the signal 802 may correspond to a delay from an expected time of transmission (e.g., according to a protocol of the scanning sequence such as a constant delay between pulses). In this regard, the range 806 may be determined based on a difference between the expected time of transmission based on the time synchronization and the time of arrival. For instance, an estimate of the speed of transmission (c) (e.g., speed of light in Earth's atmosphere, speed of sound for sonar signals in water, etc.) may be used to calculate the range based on the time of arrival, such that range=c*(time of arrival−expected time of transmission).
In some embodiments, the receiver node 104 is configured to determine an authenticity of the signals 802 based on the parameter.
In some embodiments, the system 100 (e.g., receiver node 104) is configured to establish an explicit data transfer link between the receiver node 104 and the transmitter node 102. For example, such an explicit data transfer link may transfer explicit data (e.g., bytes of data) such as WiFi, Bluetooth, long range explicit Radio Frequency transmissions, and/or the like. In some examples, the system 100 is configured to determine an authenticity of the explicit data (e.g., data packets) of the explicit data transfer link based on the parameter. For example, a difference larger than a difference threshold (e.g., more than 10%) between an expected time of arrival, expected frequency offset, and/or the like corresponding to an expected range 806 and/or expected bearing angle 804 may be used to determine the inauthenticity/authenticity of a signal. For instance, a comparison of a calculated range based on the time synchronization and a scanning sequence to an expected range 806 of a signal 802 determined based on known relative positions of transmitter nodes 102 may be used to authenticate a signal 802. A (calculated) bearing angle based on a scanning sequence and time of arrival may also be compared to an expected bearing angle 804.
In some embodiments, the parameter comprises a frequency offset of the signals relative to a common reference frequency. For example, the frequency offset may include or be indicative of a calculated net frequency shift as disclosed in U.S. patent application Ser. No. 18/130,285, filed Apr. 3, 2023, which is herein incorporated by reference in its entirety. For example, in some embodiments of U.S. patent application Ser. No. 18/130,285, a zero value or near zero value (e.g., or the like such as a zero crossing) of a calculated net frequency shift of a received signal is used to determine a bearing angle between the source (e.g., Tx node 104) and the receiving node using a time-of-arrival of the received signal. For instance, the frequency offset may be the difference between a common reference frequency and the actual received frequency of the signals 802, or multiple values thereof. The multiple values of the frequency offset may be used to determine a transmission angle. For example, if a pulse with a frequency offset equal to a particular value and which was received in a time slot corresponding to 130 degree transmission angle from East, and a second pulse with a second frequency offset equal to a second value which is opposite the particular value is received at a second time slot corresponding to a 140 degree transmission angle, then the receiver node 104 may be configured to interpolate the two frequency offset values paired with times of arrival to determine that a 135 degree transmission angle would correspond with a zero-value transmission angle. In this regard, the receiver node 104 may use the frequency offset and time of arrival of one or more pulses of signals 802 to determine the transmission angle, which is opposite the bearing angle 804.
In some embodiments, the parameter comprises a plurality of parameters. In some embodiments, determining the authenticity includes performing a multi-parameter analysis of a plurality of parameters of the signals 802. For example, the plurality of parameters may include one or more of the following: a time of arrival; a bearing angle; and a frequency offset. For instance, a multi-parameter analysis may be any calculations configured to determine a discrepancy, inconsistency, and/or the like of the plurality of parameters. For example, a difference threshold of 5% on two or more of the plurality of parameters may be used to determine authenticity. By way of another example, an inconsistency of a parameter over time, such as a range 806 that varies back and forth, or jumps in value by more than a threshold value or percentage (e.g., 1%, 2%, 5%, 10%) over time may be indicative of an adversarial node attempting to spoof a signal 802.
For at least purposes of this disclosure, ‘Doppler nulling’ means ‘Doppler null steering’, ‘Doppler null scanning’, and the like.
It is to be understood that embodiments of the methods disclosed herein may include one or more of the steps described herein. Further, such steps may be carried out in any desired order and two or more of the steps may be carried out simultaneously with one another. Two or more of the steps disclosed herein may be combined in a single step, and in some embodiments, one or more of the steps may be carried out as two or more sub-steps. Further, other steps or sub-steps may be carried in addition to, or as substitutes to one or more of the steps disclosed herein.
Although inventive concepts have been described with reference to the embodiments illustrated in the attached drawing figures, equivalents may be employed and substitutions made herein without departing from the scope of the claims. Components illustrated and described herein are merely examples of a system/device and components that may be used to implement embodiments of the inventive concepts and may be replaced with other devices and components without departing from the scope of the claims. Furthermore, any dimensions, degrees, and/or numerical ranges provided herein are to be understood as non-limiting examples unless otherwise specified in the claims.
Number | Name | Date | Kind |
---|---|---|---|
3025519 | Brown et al. | Mar 1962 | A |
4134113 | Powell | Jan 1979 | A |
4399531 | Grande et al. | Aug 1983 | A |
4806934 | Magoon | Feb 1989 | A |
5835482 | Allen | Nov 1998 | A |
5898902 | Tuzov | Apr 1999 | A |
6008758 | Campbell | Dec 1999 | A |
6072425 | Vopat | Jun 2000 | A |
6115394 | Balachandran et al. | Sep 2000 | A |
6195403 | Anderson et al. | Feb 2001 | B1 |
6496940 | Horst et al. | Dec 2002 | B1 |
6662229 | Passman et al. | Dec 2003 | B2 |
6718174 | Vayanos | Apr 2004 | B2 |
6721290 | Kondylis et al. | Apr 2004 | B1 |
6744740 | Chen | Jun 2004 | B2 |
6845091 | Ogier et al. | Jan 2005 | B2 |
7023818 | Elliott | Apr 2006 | B1 |
7171476 | Maeda et al. | Jan 2007 | B2 |
7242671 | Li et al. | Jul 2007 | B2 |
7272472 | McElreath | Sep 2007 | B1 |
7299013 | Rotta et al. | Nov 2007 | B2 |
7343170 | Feeney et al. | Mar 2008 | B1 |
7417948 | Sjöblom | Aug 2008 | B2 |
7418343 | McGraw et al. | Aug 2008 | B1 |
7558575 | Losh et al. | Jul 2009 | B2 |
7573835 | Sahinoglu et al. | Aug 2009 | B2 |
7633921 | Thubert et al. | Dec 2009 | B2 |
7639652 | Amis et al. | Dec 2009 | B1 |
7679551 | Petovello et al. | Mar 2010 | B2 |
7698463 | Ogier et al. | Apr 2010 | B2 |
7719989 | Yau | May 2010 | B2 |
7729240 | Crane et al. | Jun 2010 | B1 |
7787450 | Chan et al. | Aug 2010 | B1 |
7881229 | Weinstein et al. | Feb 2011 | B2 |
7903662 | Cohn | Mar 2011 | B2 |
7983239 | Weinstein et al. | Jul 2011 | B1 |
8010287 | Frank et al. | Aug 2011 | B1 |
8036224 | Axelsson et al. | Oct 2011 | B2 |
8159397 | Feller et al. | Apr 2012 | B2 |
8159954 | Larsson et al. | Apr 2012 | B2 |
8217836 | Anderson et al. | Jul 2012 | B1 |
8218550 | Axelsson et al. | Jul 2012 | B2 |
8223660 | Allan et al. | Jul 2012 | B2 |
8223868 | Lee | Jul 2012 | B2 |
8341289 | Hellhake et al. | Dec 2012 | B2 |
8369445 | Hensley | Feb 2013 | B2 |
8490175 | Barton et al. | Jul 2013 | B2 |
8553560 | Axelsson et al. | Oct 2013 | B2 |
8599956 | Mitchell | Dec 2013 | B1 |
8614997 | Herder | Dec 2013 | B1 |
8630291 | Shaffer et al. | Jan 2014 | B2 |
8717230 | Fischi et al. | May 2014 | B1 |
8717935 | Lindem, III et al. | May 2014 | B2 |
8732338 | Hutchison et al. | May 2014 | B2 |
8798034 | Aggarwal et al. | Aug 2014 | B2 |
8824444 | Berenberg et al. | Sep 2014 | B1 |
8867427 | Taori et al. | Oct 2014 | B2 |
8880001 | Hwang et al. | Nov 2014 | B1 |
8909471 | Jinkins et al. | Dec 2014 | B1 |
8913543 | Zainaldin | Dec 2014 | B2 |
8942197 | Rudnick et al. | Jan 2015 | B2 |
8964739 | Wisehart | Feb 2015 | B1 |
8989326 | An et al. | Mar 2015 | B2 |
9075126 | Robinson | Jul 2015 | B2 |
9179475 | Koleszar et al. | Nov 2015 | B2 |
9246795 | Madaiah et al. | Jan 2016 | B2 |
9264126 | Foster et al. | Feb 2016 | B2 |
9294159 | Duerksen | Mar 2016 | B2 |
9304198 | Doerry et al. | Apr 2016 | B1 |
9325513 | Liu et al. | Apr 2016 | B2 |
9345029 | Monte et al. | May 2016 | B2 |
9355564 | Tyson et al. | May 2016 | B1 |
9430947 | Richardson et al. | Aug 2016 | B2 |
9435884 | Inoue | Sep 2016 | B2 |
9516513 | Saegrov et al. | Dec 2016 | B2 |
9523761 | Hoffmann et al. | Dec 2016 | B1 |
9544162 | Vasseur et al. | Jan 2017 | B2 |
9621208 | Snodgrass et al. | Apr 2017 | B1 |
9628285 | Császár | Apr 2017 | B2 |
9693330 | Snodgrass et al. | Jun 2017 | B1 |
9696407 | Greenleaf et al. | Jul 2017 | B1 |
9713061 | Ruiz et al. | Jul 2017 | B2 |
9766339 | Robinson et al. | Sep 2017 | B2 |
9858822 | Gentry | Jan 2018 | B1 |
9883348 | Walker et al. | Jan 2018 | B1 |
9979462 | Watson et al. | May 2018 | B2 |
9979635 | Hellhake et al. | May 2018 | B2 |
10097469 | Hui et al. | Oct 2018 | B2 |
10098051 | Mosko et al. | Oct 2018 | B2 |
10205654 | Choi et al. | Feb 2019 | B2 |
10257655 | Cody | Apr 2019 | B2 |
10365376 | Lee et al. | Jul 2019 | B2 |
10382897 | Lanes et al. | Aug 2019 | B1 |
10455521 | Hudson et al. | Oct 2019 | B2 |
10484837 | Navalekar et al. | Nov 2019 | B2 |
10509130 | Snyder et al. | Dec 2019 | B2 |
10531500 | Ulinskas | Jan 2020 | B2 |
10601684 | Hashmi et al. | Mar 2020 | B2 |
10601713 | Turgeman et al. | Mar 2020 | B1 |
10609622 | Bader et al. | Mar 2020 | B2 |
10620296 | Ezal et al. | Apr 2020 | B1 |
10622713 | Ma | Apr 2020 | B2 |
10650688 | DeRoche | May 2020 | B1 |
10719076 | Gavrilets et al. | Jul 2020 | B1 |
10785672 | Kwan et al. | Sep 2020 | B2 |
10798053 | Nolan et al. | Oct 2020 | B2 |
10838070 | Chapman et al. | Nov 2020 | B1 |
10871575 | Petrovic et al. | Dec 2020 | B2 |
10873429 | Kwon et al. | Dec 2020 | B1 |
10908277 | Roggendorf et al. | Feb 2021 | B1 |
10931570 | Kwon et al. | Feb 2021 | B1 |
10965584 | Kwon et al. | Mar 2021 | B1 |
10979348 | Kwon et al. | Apr 2021 | B1 |
10993201 | Luecke | Apr 2021 | B2 |
10999778 | Kwon et al. | May 2021 | B1 |
11071039 | Fallon et al. | Jul 2021 | B2 |
11073622 | Cohen | Jul 2021 | B2 |
11082324 | Ramanathan et al. | Aug 2021 | B2 |
11129078 | Yates et al. | Sep 2021 | B2 |
11284295 | Kwon et al. | Mar 2022 | B1 |
11290942 | Kwon et al. | Mar 2022 | B2 |
11411613 | Jorgenson et al. | Aug 2022 | B2 |
11415664 | Hammes et al. | Aug 2022 | B2 |
11443638 | Byxbe | Sep 2022 | B2 |
11500111 | Frederiksen et al. | Nov 2022 | B2 |
11528675 | Nagaraja et al. | Dec 2022 | B2 |
11536850 | Sharma et al. | Dec 2022 | B2 |
20020018448 | Amis et al. | Feb 2002 | A1 |
20030035589 | Kim | Feb 2003 | A1 |
20030151513 | Herrmann et al. | Aug 2003 | A1 |
20040012859 | Minefuji | Jan 2004 | A1 |
20040028016 | Billhartz | Feb 2004 | A1 |
20040123228 | Kikuchi et al. | Jun 2004 | A1 |
20040213239 | Lin et al. | Oct 2004 | A1 |
20040246902 | Weinstein et al. | Dec 2004 | A1 |
20050025076 | Chaudhuri et al. | Feb 2005 | A1 |
20060010170 | Lashley et al. | Jan 2006 | A1 |
20060056421 | Zaki | Mar 2006 | A1 |
20070086541 | Moon et al. | Apr 2007 | A1 |
20070097880 | Rajsic | May 2007 | A1 |
20070109182 | Budic | May 2007 | A1 |
20070109979 | Fu et al. | May 2007 | A1 |
20070223497 | Elson et al. | Sep 2007 | A1 |
20070299950 | Kulkarni | Dec 2007 | A1 |
20080107034 | Jetcheva et al. | May 2008 | A1 |
20080117904 | Radha et al. | May 2008 | A1 |
20080219204 | Lee et al. | Sep 2008 | A1 |
20080273582 | Gaal et al. | Nov 2008 | A1 |
20080291945 | Luo | Nov 2008 | A1 |
20080310325 | Yang | Dec 2008 | A1 |
20090086713 | Luo | Apr 2009 | A1 |
20090271054 | Dokken | Oct 2009 | A1 |
20090290572 | Gonia et al. | Nov 2009 | A1 |
20090318138 | Zeng et al. | Dec 2009 | A1 |
20100074101 | Skalecki et al. | Mar 2010 | A1 |
20100074141 | Nguyen | Mar 2010 | A1 |
20110006913 | Chen et al. | Jan 2011 | A1 |
20110013487 | Zhou et al. | Jan 2011 | A1 |
20110188378 | Collins et al. | Aug 2011 | A1 |
20110312279 | Tsai et al. | Dec 2011 | A1 |
20120092208 | LeMire et al. | Apr 2012 | A1 |
20120098699 | Calmettes et al. | Apr 2012 | A1 |
20130006834 | Waelbroeck et al. | Jan 2013 | A1 |
20130069834 | Duerksen | Mar 2013 | A1 |
20130100942 | Rudnick et al. | Apr 2013 | A1 |
20130195017 | Jamadagni et al. | Aug 2013 | A1 |
20130250808 | Hui et al. | Sep 2013 | A1 |
20140017196 | Han et al. | Jan 2014 | A1 |
20140018097 | Goldstein | Jan 2014 | A1 |
20140029704 | Becker | Jan 2014 | A1 |
20140188990 | Fulks | Jul 2014 | A1 |
20140229519 | Dietrich et al. | Aug 2014 | A1 |
20140236483 | Beaurepaire et al. | Aug 2014 | A1 |
20140258201 | Finlow-Bates | Sep 2014 | A1 |
20140292568 | Fleming et al. | Oct 2014 | A1 |
20150010153 | Robertson | Jan 2015 | A1 |
20150025818 | Das | Jan 2015 | A1 |
20150222479 | Kim et al. | Aug 2015 | A1 |
20150296335 | Joshi et al. | Oct 2015 | A1 |
20150326689 | Leppänen et al. | Nov 2015 | A1 |
20160139241 | Holz et al. | May 2016 | A1 |
20160150465 | Jung et al. | May 2016 | A1 |
20160189381 | Rhoads | Jun 2016 | A1 |
20160373997 | Petersen et al. | Dec 2016 | A1 |
20170111266 | Ko | Apr 2017 | A1 |
20170111771 | Haque et al. | Apr 2017 | A1 |
20170134227 | Song et al. | May 2017 | A1 |
20170149658 | Rimhagen et al. | May 2017 | A1 |
20180013665 | Ko et al. | Jan 2018 | A1 |
20180098263 | Luo et al. | Apr 2018 | A1 |
20180146489 | Jin et al. | May 2018 | A1 |
20180234336 | Schumm et al. | Aug 2018 | A1 |
20180302807 | Chen et al. | Oct 2018 | A1 |
20180317226 | Sakoda | Nov 2018 | A1 |
20190098625 | Johnson et al. | Mar 2019 | A1 |
20190222302 | Lin et al. | Jul 2019 | A1 |
20190251848 | Sivanesan et al. | Aug 2019 | A1 |
20190317207 | Schroder et al. | Oct 2019 | A1 |
20190349172 | Zhang | Nov 2019 | A1 |
20200011968 | Hammes et al. | Jan 2020 | A1 |
20200052997 | Ramanathan et al. | Feb 2020 | A1 |
20200092949 | Donepudi et al. | Mar 2020 | A1 |
20200196309 | Amouris | Jun 2020 | A1 |
20200236607 | Zhu et al. | Jul 2020 | A1 |
20200350983 | Alasti et al. | Nov 2020 | A1 |
20200371247 | Marmet | Nov 2020 | A1 |
20200396708 | Bharadwaj et al. | Dec 2020 | A1 |
20210083917 | Konishi et al. | Mar 2021 | A1 |
20210153097 | Du et al. | May 2021 | A1 |
20210201044 | Herdade et al. | Jul 2021 | A1 |
20210359752 | Wang et al. | Nov 2021 | A1 |
20210385879 | Mahalingam et al. | Dec 2021 | A1 |
20210405176 | Luo | Dec 2021 | A1 |
20220015101 | Gallagher et al. | Jan 2022 | A1 |
20220021702 | Bouthemy | Jan 2022 | A1 |
20220038139 | Löwenmark et al. | Feb 2022 | A1 |
20220069901 | Tian et al. | Mar 2022 | A1 |
20220086818 | Nam et al. | Mar 2022 | A1 |
20220094634 | Kwon et al. | Mar 2022 | A1 |
20220143428 | Goetz et al. | May 2022 | A1 |
20220159741 | Hoang et al. | May 2022 | A1 |
20220173799 | Wigard et al. | Jun 2022 | A1 |
20220198351 | Beaurepaire et al. | Jun 2022 | A1 |
20220268916 | Nagpal | Aug 2022 | A1 |
20220286254 | Cha et al. | Sep 2022 | A1 |
20220317290 | Kostanic et al. | Oct 2022 | A1 |
20220334211 | Loren et al. | Oct 2022 | A1 |
20220342027 | Loren et al. | Oct 2022 | A1 |
20220360320 | Miao et al. | Nov 2022 | A1 |
20220365165 | Kirchner et al. | Nov 2022 | A1 |
20220368410 | Ma et al. | Nov 2022 | A1 |
20220413118 | Starr et al. | Dec 2022 | A1 |
20230033690 | Factor et al. | Feb 2023 | A1 |
20230057666 | Kwon et al. | Feb 2023 | A1 |
20230081728 | Kwon et al. | Mar 2023 | A1 |
20230111316 | Ma et al. | Apr 2023 | A1 |
20230118153 | Amorim et al. | Apr 2023 | A1 |
20230133633 | Park et al. | May 2023 | A1 |
20230135149 | Krishnamurthy et al. | May 2023 | A1 |
Number | Date | Country |
---|---|---|
101330448 | Dec 2008 | CN |
101465793 | Jun 2009 | CN |
101330448 | Dec 2010 | CN |
101465793 | Feb 2011 | CN |
202257277 | May 2012 | CN |
101686179 | Jan 2013 | CN |
103067286 | Jun 2016 | CN |
107645417 | Jan 2018 | CN |
110234147 | Sep 2019 | CN |
115085799 | Sep 2022 | CN |
115688598 | Feb 2023 | CN |
102010010935 | Sep 2011 | DE |
0908022 | Apr 1999 | EP |
1912392 | Apr 2008 | EP |
2208084 | Nov 2011 | EP |
2743726 | Jun 2014 | EP |
2466964 | Dec 2017 | EP |
3026961 | Aug 2020 | EP |
2441610 | Dec 2011 | GB |
2542491 | Mar 2017 | GB |
2568122 | Nov 2019 | GB |
2598610 | Mar 2022 | GB |
4290684 | Jul 2009 | JP |
5164157 | Mar 2013 | JP |
1020040107702 | Dec 2004 | KR |
100568976 | Apr 2006 | KR |
1020060078814 | Jul 2006 | KR |
1020160071964 | Jun 2016 | KR |
2718131 | Mar 2020 | RU |
2008157609 | Mar 2009 | WO |
2012062091 | May 2012 | WO |
2012165938 | Dec 2012 | WO |
2015114077 | Aug 2015 | WO |
2015143604 | Oct 2015 | WO |
2017101575 | Jun 2017 | WO |
2018077864 | May 2018 | WO |
2019045767 | Mar 2019 | WO |
2020117427 | Jun 2020 | WO |
2020165627 | Aug 2020 | WO |
2020220233 | Nov 2020 | WO |
2021251902 | Dec 2021 | WO |
2022003386 | Jan 2022 | WO |
2022202858 | Sep 2022 | WO |
2022221429 | Oct 2022 | WO |
2022232336 | Nov 2022 | WO |
2022233042 | Nov 2022 | WO |
2022233314 | Nov 2022 | WO |
2023001520 | Jan 2023 | WO |
2023030622 | Mar 2023 | WO |
2023031904 | Mar 2023 | WO |
2023047336 | Mar 2023 | WO |
2023057655 | Apr 2023 | WO |
2023067552 | Apr 2023 | WO |
2023068990 | Apr 2023 | WO |
2023081918 | May 2023 | WO |
Entry |
---|
U.S. Appl. No. 17/233,107, filed Apr. 16, 2021, Eric J. Loren. |
U.S. Appl. No. 17/408,156, filed Aug. 20, 2021, Tj T. Kwon. |
U.S. Appl. No. 17/534,061, filed Nov. 23, 2021, William B. Sorsby. |
U.S. Appl. No. 17/857,920, filed Jul. 5, 2022, Eric. J. Loren. |
U.S. Appl. No. 63/344,445, filed May 2022, Loren. |
U.S. Appl. No. 16/369,398, filed Mar. 29, 2019, Kwon. |
U.S. Appl. No. 16/987,671, filed Aug. 2020, Kwon et al. |
U.S. Appl. No. 17/233,107, filed Apr. 2021, Loren et al. |
U.S. Appl. No. 17/541,703, filed Dec. 3, 2021, Kwon et al. |
U.S. Appl. No. 17/857,920, filed Jul. 5, 2022, Loren et al. |
DSSS in a Nutshell, Basics of Design, Research & Design Hub, Sep. 14, 2020. |
Extended Search Report for European Application No. 21188737.7 dated Dec. 10, 2021, 8 pages. |
Extended Search Report in European Application No. 21190368.7 dated Jan. 5, 2022, 10 pages. |
Kwon et al., “Efficient Flooding with Passive Clustering (PC) in Ad Hoc Networks”, Computer Communication Review. 32. 44-56. 10.1145/510726.510730, Aug. 11, 2003, 13 pages. |
Martorella, M. et al., Ground Moving Target Imaging via SDAP-ISAR Processing: Review and New Trends. Sensors 2021, 21, 2391. https://doi.org/10.3390/s21072391. |
Peng Wang, et al., “Convergence of Satellite and Terrestrial Networks: A Comprehensive Survey networks” IEEEAcess; vol. 4, Dec. 31, 2019. |
Pulak K. Chowdhury, et al. “Handover Schemes in Satellite Networks: State-of-the-Art and Future Research Directions” 4th Quarter 2006, vol. 8, No. 4, Oct. 1, 2006. |
Seddigh et al., “Dominating sets and neighbor elimination-based broadcasting algorithms in wireless networks”, IEE Transactions in Parallel and Distributed Systems, IEEE, USA, vol. 13, No. 1, Jan. 1, 2002 (Jan. 1, 2002), pp. 14-25, XP011094090, ISSN: 1045-9219, DOI 10.1109/71.9800214. |
Yi et al., “Passive Clustering in Ad Hoc Networks (PC)”, URL: https://tools.ietf,org/html/drafts-yi-manet-pc-00, Nov. 14, 2001, 31 pages. |
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Parent | 18130285 | Apr 2023 | US |
Child | 18134950 | US | |
Parent | 18196944 | May 2023 | US |
Child | 18198152 | May 2023 | US |
Parent | 18134950 | Apr 2023 | US |
Child | 18196944 | US | |
Parent | 18130285 | Apr 2023 | US |
Child | 18134950 | US | |
Parent | 18196786 | May 2023 | US |
Child | 18198152 | May 2023 | US |
Parent | 18134950 | Apr 2023 | US |
Child | 18196786 | US | |
Parent | 18130285 | Apr 2023 | US |
Child | 18134950 | US | |
Parent | 18196936 | May 2023 | US |
Child | 18198152 | May 2023 | US |
Parent | 18134950 | Apr 2023 | US |
Child | 18196936 | US | |
Parent | 18130285 | Apr 2023 | US |
Child | 18134950 | US | |
Parent | 18198025 | May 2023 | US |
Child | 18198671 | May 2023 | US |
Parent | 18196807 | May 2023 | US |
Child | 18198025 | US | |
Parent | 18196912 | May 2023 | US |
Child | 18196807 | US | |
Parent | 18196931 | May 2023 | US |
Child | 18196912 | US | |
Parent | 18196765 | May 2023 | US |
Child | 18196931 | US | |
Parent | 18196944 | May 2023 | US |
Child | 18196765 | US | |
Parent | 18196786 | May 2023 | US |
Child | 18196944 | US | |
Parent | 18196936 | May 2023 | US |
Child | 18196786 | US |