WO2023096945A1 - Système et procédé de compensation doppler entre des nœuds émetteur et récepteur - Google Patents

Système et procédé de compensation doppler entre des nœuds émetteur et récepteur Download PDF

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Publication number
WO2023096945A1
WO2023096945A1 PCT/US2022/050804 US2022050804W WO2023096945A1 WO 2023096945 A1 WO2023096945 A1 WO 2023096945A1 US 2022050804 W US2022050804 W US 2022050804W WO 2023096945 A1 WO2023096945 A1 WO 2023096945A1
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Prior art keywords
node
receiver
transmitter
receiver node
doppler
Prior art date
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PCT/US2022/050804
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English (en)
Inventor
Tj T. KWON
William B. SORSBY
Eric J. LOREN
Joseph T. GRAF
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Rockwell Collins, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US17/534,061 external-priority patent/US11665658B1/en
Priority claimed from US17/541,703 external-priority patent/US20220094634A1/en
Priority claimed from PCT/US2022/024653 external-priority patent/WO2022221429A1/fr
Priority claimed from US17/940,898 external-priority patent/US20230081728A1/en
Priority claimed from US17/941,907 external-priority patent/US20230379007A1/en
Application filed by Rockwell Collins, Inc. filed Critical Rockwell Collins, Inc.
Publication of WO2023096945A1 publication Critical patent/WO2023096945A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/0035—Synchronisation arrangements detecting errors in frequency or phase
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H04W56/002—Mutual synchronization

Definitions

  • Mobile Ad-hoc NETworks are known in the art as quickly deployable, self-configuring wireless networks with no pre-defined network topology.
  • Each communications node within a MANET is presumed to be able to move freely. Additionally, each communications node within a MANET may be required to forward (relay) data packet traffic.
  • Data packet routing and delivery within a MANET may depend on a number of factors including, but not limited to, the number of communications nodes within the network, communications node proximity and mobility, power requirements, network bandwidth, user traffic requirements, timing requirements, and the like.
  • MANETs face many challenges due to the limited network awareness inherent in such highly dynamic, low-infrastructure communication systems. Given the broad ranges in variable spaces, the challenges lie in making good decisions based on such limited information. For example, in static networks with fixed topologies, protocols can propagate information throughout the network to determine the network structure, but in dynamic topologies this information quickly becomes stale and must be periodically refreshed. It has been suggested that directional systems are the future of MANETs, but this future has not as yet been realized. In addition to topology factors, fast-moving platforms (e.g., communications nodes moving relative to each other) experience a frequency Doppler shift (e.g., offset) due to the relative radial velocity between each set of nodes. This Doppler frequency shift often limits receive sensitivity levels which can be achieved by a node within a mobile network.
  • Doppler shift e.g., offset
  • radio silence is a status in which some or all fixed or mobile nodes in an area are asked to stop transmitting for safety or security reasons.
  • a system may include a transmitter node and a receiver node.
  • Each node may include a communications interface including at least one antenna element and 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.
  • Each node of the transmitter node and the receiver node may be in motion relative to each other.
  • Each node may be time synchronized to apply Doppler corrections associated with said node’s own motions relative to a common reference frame.
  • the common reference frame may be known to the transmiter 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.
  • the receiver node may be configured to be in a state of reduced emissions.
  • a method 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 relative to each other, 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; 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; and 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
  • FIG. 1 is a diagrammatic illustration of a mobile ad hoc network (MANET) and individual nodes thereof according to example embodiments of this disclosure.
  • MANET mobile ad hoc network
  • FIG. 2A is a graphical representation of frequency shift profiles within the MANET of FIG. 1.
  • FIG. 2B is a graphical representation of frequency shift profiles within the MANET of FIG. 1.
  • FIG. 3 is a diagrammatic illustration of a transmitter node and a receiver node according to example embodiments of this disclosure.
  • FIG. 4A is a graphical representation of frequency shift profiles within the MANET of FIG. 3.
  • FIG. 4B is a graphical representation of frequency shift profiles within the MANET of FIG. 3.
  • FIG. 5 is an exemplary graph of sets for covering space.
  • FIG. 6 is a diagrammatic illustration of a transmitter node and a receiver node according to example embodiments of this disclosure.
  • FIG. 7 is a flow diagram illustrating a method according to example embodiments of this disclosure.
  • FIG. 8 is a diagrammatic illustration of nodes in an EMCON DELTA state.
  • FIG. 9A is a diagrammatic illustration of a primary node and secondary nodes in an EMCON ALPHA state.
  • FIG. 9B is a diagrammatic illustration of a primary node and secondary nodes in an EMCON ALPHA state with secondary node transmissions, according to example embodiments of this disclosure.
  • 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 , 1 a, 1 b).
  • 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.
  • 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.
  • embodiments of the inventive concepts disclosed herein are directed to a method and a system for achieving situational awareness during radio silence including a transmitter node and a receiver node, which may be time synchronized to apply Doppler corrections associated with said node’s own motions relative to a common reference frame.
  • a primary node e.g., high value asset
  • secondary nodes e.g., expendable assets
  • a primary node may gain situational awareness of secondary nodes while maintaining its own radio silence — thereby reducing a risk of being detected or located by adverse nodes.
  • embodiments may utilize spatial awareness (e.g., doppler nulling) methods including transmitter and receiver nodes being time synchronized to apply Doppler corrections.
  • doppler nulling methods include, but are not limited to, methods and any other descriptions disclosed in U.S. Patent Application No. 17/233,107, filed April 16, 2021 , which is hereby incorporated by reference in its entirety; and U.S. Patent Application No. 17/857,920, filed July 5, 2022, which is hereby incorporated by reference in its entirety.
  • 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).
  • 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.
  • Some other communication protocols may require a higher signal to noise ratio (SNR) than doppler nulling methods.
  • SNR signal to noise ratio
  • doppler nulling methods may allow for using relatively less power (e.g., watts) and a weaker signal, while still providing for situational awareness, than other methods.
  • Some other communication protocols, in order to provide for situational awareness, may require two-way communications of both the transmitter node and the receiver node in order to establish a communication link and to send attributes (e.g., location information data) of a transmitting node, thereby breaking radio silence of the receiving node.
  • a stationary receiver may determine a cooperative transmitter’s direction and velocity vector by using a Doppler null scanning approach in two dimensions.
  • a benefit of the approach is the spatial awareness without exchanging explicit positional information.
  • Other benefits include discovery, synchronization, and Doppler corrections which are important for communications.
  • Some embodiment may combine coordinated transmitter frequency shifts along with the transmitter’s motion induced Doppler frequency shift to produce unique net frequency shift signal characteristics resolvable using a stationary receiver to achieve spatial awareness. Further, some embodiment may include a three- dimensional (3D) approach with the receiver and the transmitter in motion.
  • 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.
  • a common reference frame e.g., a common inertial reference frame, such as the Earth, which may ignore the curvature of Earth
  • 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.
  • some embodiments utilize the Doppler effect to discriminate between directions with the resolution dictated by selected design parameters.
  • 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 transmitters velocity.
  • 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.
  • any suitable step size of degrees may be used for Doppler null scanning.
  • one of the contributions of some embodiments is passive spatial awareness.
  • spatial information for neighbor nodes can be learned via data communication.
  • GPS global positioning system
  • data communication is only possible after the signals for neighbor nodes have been discovered, synchronized and Doppler corrected.
  • 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.
  • 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.
  • highly efficient mobile ad hoc networking MANET
  • Embodiments may improve the functioning of a network, itself.
  • the multi-node communications network 100 may include multiple communications nodes, e.g., a transmitter (Tx) node 102 and a receiver (Rx) node 104.
  • Tx transmitter
  • Rx receiver
  • the multi-node communications network 100 may include any multi-node communications network known in the art.
  • the multi-node communications network 100 may include a mobile ad-hoc network (MANET) 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.
  • the Tx and Rx nodes 102, 104 may include any communications node known in the art which may be communicatively coupled.
  • the Tx and Rx nodes 102, 104 may include any communications node known in the art for transmitting/transceiving data packets.
  • 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.
  • the Rx node 104 of the muiti-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.
  • 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 (FRGA) 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.
  • 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.
  • the memory 108 can stere 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.
  • 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.
  • RAM random-access memory
  • ROM read-only memory
  • flash memory e.g., a secure digital (SD) memory card, a mini-SD memory card, and/or a micro-SD memory card
  • SSD solid-state drive
  • magnetic memory magnetic memory
  • optical memory optical memory
  • USB universal serial bus
  • the communication interface 110 can be operatively configured to communicate with components of the Rx node 104.
  • 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 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.
  • the communication interface 110 includes or is coupled to a transmitter, receiver, transceiver, physical connection interface, or any combination thereof.
  • 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 multinode 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.
  • 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.
  • the Tx node 102 and Rx node 104 may both be moving in an arbitrary direction at an arbitrary speed, and may similarly be moving relative to each other.
  • the Tx node 102 may be moving relative to the Rx node 104 according to a velocity vector 116, at a relative velocity VT X and a relative angular direction (an angle a relative to an arbitrary direction 118 (e.g., due east); 0 may be the angular direction of the Rx node relative to due east.
  • 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 $ relative to the arbitrary direction 118).
  • the transmitting waveform e.g., the communications interface 110 of the Tx node 102
  • the transmitting waveform may be informed by the platform (e.g., the controller 106) of its velocity vector and orientation (e.g., a Vr) and may adjust its transmitting frequency to remove the Doppler frequency shift at each Doppler nulling direction 120 and angle ⁇ p-
  • the Doppler shift is a physical phenomenon due to motion and can be considered as a channel effect.
  • 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: 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 (p7
  • the receiver node 104 has an implementation that resoives the frequency of the incoming signal, as would be understood to one of ordinary skill in the art.
  • the amplitude is consistent with the transmitter node's 102 speed of 5 ppm [p T
  • 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 FIG. 2A, and ⁇ 90 degrees in FIG. 2B) so there is initially an instance of ambiguity in position direction. In this case the receiver node 104 knows the transmitter node 102 is either East or West of the receiver node 104.
  • the multi-node communications network 100 may include multiple communications nodes, e.g., a transmitter (Tx) node 102 and a receiver (Rx) node 104. As shown in FIG. 3 both of the transmitter node 102 and the receiver node 104 are in motion in two dimensions.
  • Tx transmitter
  • Rx receiver
  • the simultaneous movement scenario is depicted in FIG. 3 where the receiver node 104 is also moving in a generic velocity characterized by a speed
  • the protocol for the moving receiver node 104 incorporates a frequency adjustment on the receiver node’s 104 side to compensate for the receiver node’s 104 motion as well.
  • the equations have two additional terms. One is a Doppler term for the motion of the receiver and the second is frequency compensation by the receiver.
  • 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 and velocity direction (a). That transmitter node frequency adjustment is proportional to the velocity projection onto the ‘Null’ direction (cp) and is the first term in the equation below.
  • receiver node 104 It is the job of the receiver node 104 to adjust the receiver node frequency according to the receiver node’s 104 own speed and velocity direction (/?). That receiver node frequency adjustment is proportional to the velocity projection onto the ‘Null’ direction ($) 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.
  • receiver node 104 has an implementation that resolves the frequency of the incoming signal, as would be understood in the art.
  • FIGS. 4A and 4B The net frequency shift for the two-dimensional (2D) moving receiver node 104 approach is shown in FIGS. 4A and 4B for several scenario cases of receiver node location, 0, and transmitter node and receiver node speeds as well as transmitter node and receiver node velocity direction (a and P).
  • FIG. 4B has the same speed for the transmitter node and receiver node.
  • FIG. 5 shows a number of direction sets needed to span 3D and 2D space with different cone sizes (cone sizes are full width).
  • it worth commenting on the size of the space when including another dimension. For example, when a ‘Null’ step size of 10 degrees was used in the previous examples, it took 36 sets to span the 360 degrees in 2D.
  • an exemplary detection angle of 10 degrees e.g., a directional antenna with 10-degree cone
  • the 3D fractional coverage can be computed by calculating the coverage of a cone compared to the full 4 pi steradians. The fraction is equal to the integral
  • the number of sets to span the space is shown in FIG. 5 for both the 2D and 3D cases which correlates with discovery time. Except for narrow cone sizes, the number of sets is not drastically greater for the 3D case (e.g., approximately 15 times at 10 degrees, 7.3 time at 20 degrees, and around 4.9 times at 30 degrees). Unless systems are limited to very narrow cone sizes, the discovery time for 3D searches is not overwhelming compared to a 2D search.
  • the multi-node communications network 100 may include multiple communications nodes, e.g., a transmitter (Tx) node 102 and a receiver (Rx) node 104. As shown in FIG. 6 both of the transmitter node 102 and the receiver node 104 are in motion in three dimensions.
  • Tx transmitter
  • Rx receiver
  • FIG. 6 shows the geometry in 3 dimensions where Direction is the unit vector pointing to the receiver from the transmitter, and Null is the unit vector pointing in the ‘Null’ direction defined by the protocol.
  • the nulling protocol adjusts the transmit node frequency and receiver node frequency due to their velocity projections onto the Null direction
  • 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 and are parallel and is a minimum when they are antiparallel. Furthermore, the relative speed is determined by the amplitude,
  • the system may include a transmitter node 102 and a receiver node 104.
  • Each node of the transmitter node 102 and the receiver node 104 may include a communications interface 110 including at least one antenna element 112 and a controller operatively coupled to the communications interface, the controller 106 including one or more processors, wherein the controller 106 has information of own node velocity and own node orientation.
  • the transmitter node 102 and the receiver node 104 may be in motion (e.g., in two dimensions or in three dimensions).
  • the transmitter node 102 and the receiver node 104 may be time synchronized to apply Doppler corrections associated with said node’s own motions relative to a common reference frame (e.g., a common inertial reference frame (e.g., a common inertial reference frame in motion or a stationary common inertial reference frame)).
  • the common reference frame may be known to the transmitter node 102 and the receiver node 104 prior to the transmitter node 102 transmitting signals to the receiver node 104 and prior to the receiver node 104 receiving the signals from the transmitter node 102.
  • the system is a mobile ad-hoc network (MANET) comprising the transmitter node 102 and the receiver node 104.
  • MANET mobile ad-hoc network
  • the transmitter node 102 and the receiver node 104 are time synchronized via synchronization bits associated with acquisition.
  • the synchronization bits may operate as physical layer overhead.
  • 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.
  • 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.
  • 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.
  • 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 m inus the velocity vector of the transmitter node 102.
  • 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.
  • 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.
  • an exemplary embodiment of a method 700 may include one or more of the following steps. Additionally, for example, some embodiments may include performing one or more instances of the method 700 iteratively, concurrently, and/or sequentially. Additionally, for example, at least some of the steps of the method 700 may be performed in parallel and/or concurrently. Additionally, in some embodiments, at least some of the steps of the method 700 may be performed non-sequentially.
  • 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.
  • the method 700 may include any of the operations disclosed throughout.
  • the null scanning 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 ultrasensitive spatial awareness with relatively low power.
  • situational awareness during reduced emissions e.g., radio silence of at least one node
  • radio silence may mean that no radiations/transmissions are permitted by a node in a radio silence state, such as maybe referred to as a complete black out (e.g., no communications, no radar, and the like).
  • situational awareness data e.g., detection, location, and the like
  • optical observations e.g., line of sight observations by personnel, passive optical cameras, and the like
  • nodes in radio silence may be used by nodes in radio silence to detect other nodes (e.g., aircraft, boats, UAVs, or any other system).
  • being in a radio silence state may still allow receiving signals from other nodes to acquire situational awareness.
  • a node in radio silence may still learn of other nodes’ locations and attributes (e.g., velocity, bearing).
  • node attributes e.g., identity, location, speed
  • adverse listening nodes e.g., third party nodes, enemy combatants, and the like
  • identifying friendly nodes e.g., allied UAVs
  • the friendly nodes are not allowed to transmit any signal at all.
  • secondary nodes e.g., expendable and/or lower value assets, UAVs, and the like
  • primary nodes e.g., high value assets, battleships, and the like
  • a challenge of transmitting attributes e.g., location, speed, bearing, and the like
  • typical transmission techniques e.g., non-doppler nulling methods
  • such techniques may require two-way links (which may give away locations of high value assets.
  • such techniques may require relatively high power to increase SNR and travel distance of the signal, which may increase a likelihood of detection.
  • attributes e.g., location data
  • doppler nulling methods may allow for a cure or reduction in at least some of the deficiencies of other techniques stated above.
  • time-synchronized doppler nulling scanning techniques may allow for using far lower strength signals that allow a signal to travel much farther than a signal of typical communication techniques.
  • an adverse node may be limited in its ability to determine attributes (e.g., speed, bearing) of the node that sent the signal and thereby have less situational awareness than primary nodes configured to use doppler nulling methods.
  • primary nodes may include knowledge of a common reference frame and time-synchronization protocol for calculating attributes of the node that sent the signal using doppler nulling communication protocols but adverse nodes do not necessarily have such knowledge.
  • a state of reduced emissions includes any communication protocol, limitation, status, state, directive, order, or the like configured to reduce which types of transmissions are allowed to be used for a period that the state of reduced emissions is in effect. For example, limits on the type, number, power level, or the like of allowed signals (e.g., transmissions) may be imposed during the state of reduced emissions.
  • a state of reduced emissions includes, but is not limited to, radio silence, Emissions Control (EMCON), and the like.
  • EMCON Emissions Control
  • EMCON may include EMCON communication protocols.
  • EMCON states may include, but are not necessarily limited to, EMCON DELTA, EMCON CHARLIE, EMCON BETA, and EMCON ALPHA states used in the military (e.g., navy).
  • EMCON DELTA may mean no or minimal emission limitations and may be used during normal operations.
  • EMCON CHARLIE may mean only mission-essential equipment is allowed to transmit. For example, sensors unique to the vessel may be turned off to prevent identification or classification by adverse nodes.
  • EMCON BETA may mean even more limitations than EMCON CHARLIE, but some transmissions may still be allowed.
  • EMCON ALPHA may mean complete radio silence, such that no nodes in such a state are allowed to transmit.
  • FIGS. 8 - 9A show a primary node 802 and secondary nodes 804 in various states, including EMCON-based reduced emission states. At least some of the depictions of FIGS. 8 - 9A are in accordance with one or more embodiments of the present disclosure.
  • a primary node 802 (e.g., high value asset) may include (or be) a receiving node, Rx node, and the like, and vice versa.
  • a secondary node (e.g., expendable asset) may include (or be) a transmitter node, Tx node, and the like, and vice versa.
  • FIG. 8 shows a diagrammatic illustration of nodes 802, 804 in an EMCON DELTA state.
  • situational awareness 806 may be determined by a primary' node 802 of secondary node attributes when all nodes 802, 804 are permitted to transmit.
  • the situational awareness 806 may be determined using doppler nulling methods.
  • an advantage of such an EMCON DELTA state may include that the situational awareness 806 (e.g., set of all known nodes and attributes of those nodes) includes knowledge of the secondary nodes 804 by the primary node 802.
  • a disadvantage of such an EMCON DELTA state may include that third party (e.g., adverse) nodes may be able to intercept a signal of the primary node 802 and thereby detect the primary node 802.
  • FIG. 9A shows a diagrammatic illustration of the primary node 802 and the secondary nodes 804 in an EMCON ALPHA state, where no node is transmitting.
  • An advantage of such an EMCON ALPHA state may include that third party (e.g., adverse) nodes may be unable to detect and/or have reduced ability to determine attributes of the primary node 802.
  • a disadvantage of such an EMCON DELTA state may include that the primary node 802 may have limited situational awareness 808 of the secondary nodes 804.
  • FIG. 9B shows a diagrammatic illustration of the primary node 802 and the secondary nodes 804 in an EMCON ALPHA state with secondary node transmissions allowed, according to example embodiments of this disclosure.
  • An advantage of such an EMCON DELTA state with secondary node transmissions may include that the primary' node 802 may have situational awareness 810 of the secondary nodes 804, while third party (e.g., adverse) nodes may be unable to detect and/or have reduced ability to determine atributes of the primary node 802.
  • the signals transmitted by the secondary nodes 804 (e.g., transmiter nodes) to the primary node 802 (e.g., receiver node) include low probability of detection (LPD) signals.
  • LPD low probability of detection
  • the secondary nodes 804 may utilize oneway LPD beacon transmissions.
  • EMCON CHARLIE state where mission-essential equipment may transmit but at least some sensors are prohibited from transmitting
  • advantages and disadvantages may be similar to FIG. 8, for EMCON DELTA.
  • a disadvantage of such an EMCON CHARLIE state may include that third party nodes may be able to intercept a signal of the primary node 802 and thereby detect the primary node 802.
  • Location information may include, but is not limited to, Position Location Information/Precise Position Location Information (PLI/PPLI), such as may be used in military operations.
  • PLI Position Location Information/Precise Position Location Information
  • EMCON BETA state showing an EMCON DELTA state.
  • a disadvantage of an EMCON BETA state with PLI/PPLI allowed may include that third party nodes may be able to intercept a signal of the primary node 802 and thereby detect the primary node 802.
  • the advantages and disadvantages may be similar to FIG. 9A showing an EMCON ALPHA state with no transmissions by the second nodes.
  • a disadvantage of an EMCON BETA state with location information disallowed may include that the situational awareness 808 does not include knowledge of the secondary nodes 804.
  • At least some embodiments allow for a high value asset to achieve situational awareness of a variety of nodes (e.g., Tx nodes of various assets such as UAVs, which may be assets that are less critically valuable) while avoiding detection such that a network of such nodes may provide for relatively high protection of high value assets while still providing situational awareness to such high value assets.
  • nodes e.g., Tx nodes of various assets such as UAVs, which may be assets that are less critically valuable
  • 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.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Un système peut comprendre un nœud émetteur et un nœud récepteur. Chaque nœud peut comprendre une interface de communication comprenant au moins un élément antenne et un dispositif de commande couplé fonctionnellement à l'interface de communication, le dispositif de commande comprenant un ou plusieurs processeurs, le dispositif de commande comprenant des informations de vitesse et d'orientation propres au nœud. Chaque nœud parmi le nœud émetteur et le nœud récepteur peut être en mouvement l'un par rapport à l'autre. Chaque nœud peut être synchronisé dans le temps pour appliquer des corrections Doppler associées auxdits mouvements propres au nœud par rapport à une trame de référence commune. La trame de référence commune peut être connue du nœud émetteur et du nœud récepteur avant que le nœud émetteur ne transmette des signaux au nœud récepteur et avant que le nœud récepteur ne reçoive les signaux du nœud émetteur. Le nœud récepteur peut être configuré pour se trouver dans un état d'émissions réduites.
PCT/US2022/050804 2021-11-23 2022-11-22 Système et procédé de compensation doppler entre des nœuds émetteur et récepteur WO2023096945A1 (fr)

Applications Claiming Priority (16)

Application Number Priority Date Filing Date Title
US17/534,061 2021-11-23
US17/534,061 US11665658B1 (en) 2021-04-16 2021-11-23 System and method for application of doppler corrections for time synchronized transmitter and receiver
US17/541,703 2021-12-03
US17/541,703 US20220094634A1 (en) 2019-11-27 2021-12-03 System and method for spatial awareness network routing
USPCT/US2022/024653 2022-04-13
PCT/US2022/024653 WO2022221429A1 (fr) 2021-04-16 2022-04-13 Système et procédé de détermination de direction de voisinage et de vitesse relative par l'intermédiaire de techniques d'annulation doppler
US202263344445P 2022-05-20 2022-05-20
US63/344,445 2022-05-20
US17/857,920 2022-07-05
US17/857,920 US20220342027A1 (en) 2021-04-16 2022-07-05 System and method for application of doppler corrections for time synchronized transmitter and receiver in motion
US202263400138P 2022-08-23 2022-08-23
US63/400,138 2022-08-23
US17/940,898 2022-09-08
US17/940,898 US20230081728A1 (en) 2019-11-27 2022-09-08 System and method using passive spatial awareness for geo network routing
US17/941,907 US20230379007A1 (en) 2022-05-20 2022-09-09 Situational awareness (sa) in radio silence (spatial awareness)
US17/941,907 2022-09-09

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