System and method for multi-transceiver communication in dense areas using doppler-division multiple access and adaptive search / lock

Abstract

A system and method for multi-transceiver communication among a plurality of independent electromagnetic transceivers in dense areas using Doppler-division multiple access and adaptive search / lock.

Description

[0001] SYSTEM AND METHOD FOR MULTI-TRANSCEIVER COMMUNICATION IN DENSE AREAS USING DOPPLER-DIVISION MULTIPLE ACCESS AND ADAPTIVE

[0002] SEARCH / LOCK

[0003] RELATED APPLICATIONS

[0004] This application claims the benefit of priority under 35 USC §119(e) of U.S. Provisional Patent Application No. 63 / 714,166 filed on 31 October, 2024, the contents of which are incorporated herein by reference in their entirety.

[0005] FIELD AND BACKGROUND OF THE INVENTION

[0006] The present invention, in some embodiments thereof, relates to a system and method to communicate data between a plurality of devices in a small geographical area and, more particularly, but not exclusively, when the devices are “off the shelf’ Doppler radar and / or lidar transceivers.

[0007] United States Patent Publication No. 2023 / 0176187 appears to disclose, “Transmitting antennas and receiving antennas are arranged such that a plurality of virtual antennas have the same position in a time-division-multiplexed (TDM) frequency modulated continuous wave (FMCW) radar apparatus. At least three peculiar chirps, at least one of which is included in a chirp loop of each of waveform signals transmitted by the plurality of virtual antennas having the same position, are respectively positioned in consecutive time slots and have different periods. A Doppler frequency may be uniquely determined from phase difference values between the at least three peculiar chirps respectively positioned in consecutive time slots measured from FMCW radar signals received at the plurality of virtual antennas.”

[0008] Additional art includes United States Patent No. 11,693,106, United States Patent Publication No. 2024 / 0103123, United States Patent Publication No. 2022 / 0120890, and United States Patent No. 9,678,216.

[0009] BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

[0011] In the drawings:

[0012] FIG. 1 is a flow diagram describing a use of a system, in accordance with an embodiment of the current invention.

[0013] FIG. 2 is a block diagram describing a system, in accordance with an embodiment of the current invention.

[0014] FIG. 3 is a schematic diagram illustrating a system, in accordance with an embodiment of the current invention.

[0015] FIG. 4 is a schematic diagram illustrating a moving search window, in accordance with some embodiments of the current invention.

[0016] FIG. 5 is a table of exemplary radar and lidar frequency / wavelength bands relevant to the searched / shared band, in accordance with some embodiments of the current invention.

[0017] FIG. 6 is a block diagram illustrating a system for multi-transceiver communication, in accordance with some embodiments of the current invention.

[0018] FIG. 7 is a flow chart illustrating a method for communication among independent frequency modulated continuous wave (FMCW) units, in accordance with some embodiments of the current invention.

[0019] FIG. 8 is a block diagram illustration of a system for multi-transceiver communication, in accordance with an embodiment of the current invention.

[0020] SUMMARY OF THE INVENTION

[0021] A system of one or more computers can be configured to perform particular operations or actions by virtue of having software, firmware, hardware, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. One or more computer programs can be configured to perform particular operations or actions by virtue of including instructions that, when executed by data processing apparatus, cause the apparatus to perform the actions.

[0022] In one general aspect, system may include a plurality of independent electromagnetic transceivers configured to transmit frequency modulated continuous wave (FMCW) chirps and to receive peer signals. System may also include a receiver chain of each transceiver including an intermediate-frequency bandwidth. System may furthermore include control circuitry configured to: (i) sweep a moving search window over frequency and offset while correlating against a chirp template; (ii) detect a peer’s narrowband when correlation exceeds a threshold and a frequency error is less than or equal to the smallest increment the receiver uses to tune the search; (iii) retune a local synthesizer or digital oscillator to reduce a limit of a range resolution of the system for a number of consecutive chirps; and (iv) establish two-way communication on the detected narrowband, where simultaneous links are separated using Doppler-Division Multiple Access (DDMA) with distinct slow-time phase increments. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0023] In one general aspect, system may include a plurality of independent electromagnetic transceivers configured to transmit signals and to receive peer signals. System may also include a receiver chain of each transceiver including an intermediate-frequency passband. System may furthermore include control circuitry configured for: (i) sweeping a moving search window over frequency and offset while correlating against a signal template; (ii) detecting a peer’s narrowband when correlation exceeds a threshold and a frequency error is less than or equal to a threshold; (iii) retuning a local receiver and transmitter to increase agreement with the detected narrow band; and (iv) establishing two-way communication on the detected narrowband. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0024] Implementations may include one or more of the following features. System where communication occurs on simultaneous links within the wideband and the simultaneous links are separated using Doppler-Division Multiple Access (DDMA) with distinct slow-time phase increments. System where said retuning includes retuning a synthesizer or a digital oscillator. System where said retuning reduces a limit of a range resolution for a number of consecutive signals. System where the number of consecutive signals ranges between about 416. System where said signal includes a sweep signal. System where said signal includes a chirp. System where the signal is a FMCW signal. System where the intermediate-frequency passband has a bandwidth ranging between 14 MHz. System where the frequency error ranges between 10100 kHz. System where band allocation is ad-hoc via handshake. System where band allocation is by a coordinator device. System where collisions trigger random back-off and re-scan. System may include authentication using a rolling code or message authentication code. System where Time Division Multiple Access (TDMA) time slots and Frequency Division Multiple Access (FDMA) sub-bands are combined with DDMA. System where the transceivers are radar units operating in at least one of L, S, C, X, Ku, K, Ka, V, or W bands. System where the transceivers are lidar units operating at about 4001550. System where the threshold is less than or equal to the smallest increment the receiver uses to tune the search. Implementations of the described techniques may include hardware, a method or process, or a computer tangible medium.

[0025] In one general aspect, the method may include scanning a wideband with a moving search window. The method may also include detecting a narrowband of a peer within an intermediate frequency acceptance band of the search window. The method may furthermore include retuning to achieve a link with frequency lock. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0026] Implementations may include one or more of the following features. The method may include: exchanging data on the narrowband while coordinating multiple links via distinct slowtime phase increments. The method where said multiple links are across orthogonal Doppler offsets. The method may include: assigning a Doppler phase increment to the link. The method may include combining DDMA with time division multiple access (TDMA). The method may include combining DDMA with frequency division multiple access (FDMA). The method where the frequency modulated continuous wave (FMCW) unit is a radar or lidar. The method further where the retuning includes retuning a synthesizer and / or a digital resampler using a band adjuster to achieve lock. The method where units are stationary within a small geographic area. The method may include advertising occupied resources so neighboring units avoid interference. The method where the advertising includes announcing at least one of a phase increment, time slot, and frequency. Non - transitory computer - readable medium storing instructions. Implementations of the described techniques may include hardware, a method or process, or a computer tangible medium.

[0027] DESCRIPTION OF THE INVENTION

[0028] The present invention, in some embodiments thereof, relates to a system and method to communicate data between a plurality of devices in a small geographical area and, more particularly, but not exclusively, when the devices are “off the shelf’ Doppler radar and / or lidar transceivers.

[0029] DEFINITIONS

[0030] As used herein, the term “sweep signal” refers to a signal that changes frequency over time within a specific bandwidth. A “chirp signal” is a type of sweep signal in which the frequency increases or decreases with time. In some sources, the term “chirp” is used interchangeably with “sweep signal”, and is a standard in spread-spectrum communications, sonar, radar, and laser systems.

[0031] As used herein, the term “Frequency -Modulated Continuous Wave radar” or “FMCW” may relate to a type of radar system that transmits a continuous signal whose frequency changes over time. FMCW radar continuously transmits a signal whose frequency is constantly changing. When this signal encounters a target, it is reflected back to the radar. By comparing the reflected signal to the original transmitted signal, the radar can determine the target's distance and speed. FMCW radar offers high range resolution and accurate Doppler velocity measurement, making it suitable for applications requiring precise distance and speed information. The FMCW system can scan a wide range of frequencies for Doppler effect echoes. The frequency range can be adjusted. The FMCW system can also transmit a spread spectrum "chirp" signal that covers a significant frequency band, The form and bandwidth of the FMCW signal can be adjusted. This means that each device occupies a large band in the frequency spectrum.

[0032] As used herein, the term “Time Division Multiple Access” or “TDMA” may relate to a digital modulation technique used in digital and radio communication. The limited spectrum available over a frequency channel is divided into different time slots, enabling multiple users to share the same frequency. This facilitates simultaneous conversations and increases the amount of data that can be carried over the channel.

[0033] As used herein, the term “Frequency Division Multiple Access” or “FDMA” may relate to a channel access method in which the available frequency spectrum is divided into smaller frequency channels, each employed by a specific user or group of users.

[0034] As used herein, the term “Doppler radar” may relate to a type that detects a return signal at a frequency that has been changed from the outgoing signal. The radar measures the Doppler shift of a reflected signal to determine a target's relative velocity. This shift in frequency is caused by the relative motion between the radar and the target and / or intentionally induced by the transmitter.

[0035] As used herein, the term Doppler Division Multiple Access (DDMA)” may relate to a technique that separates signals from different transmit antennas by shifting their frequencies in the Doppler domain. DDMA assigns distinct slow-time phase increments to different links such that each link occupies a unique Doppler offset.

[0036] As used herein, the term Slow Time tsrefers to the time index corresponding to the serial number of a sequence of transmitted chirps (or pulses). The Doppler dimension is the resultant frequency domain axis obtained by performing a Fourier Transform (such as an FFT) along the Slow Time axis. Thus, the Slow Time measurement is the raw data input used to calculate the final Doppler dimension. In convention FMCW radar the Doppler dimension may represent the target's radial velocity. As used herein, the term “moving search window” may relate to a receiver procedure that sweeps frequency and / or offset to acquire a peer’s narrowband despite unknown clock and / or offset.

[0037] As used herein, the term “offset search window” may relate to a sweep of receiver mixing conditions configured to accept a peer chirp with a frequency / time offset within a selected range of frequencies, ±Af.

[0038] As used herein, the terms “wideband” and “narrowband” may refer to the communication band before and after acquisition, respectively.

[0039] As used herein, the term “high-band” may relate to wave or optical carrier frequencies of used for Frequency -Modulated Continuous Wave (FMCW) radar and / or lidar about 60-100 GHz; particularly 76-81 GHz.

[0040] As used herein, the term “medium band” may relate to wave radar / lidar carrier frequencies of about 1 GHz-60 GHz.

[0041] As used herein, the term “low-band” may relate to wave radar and / or lidar carrier frequencies which are sub-GHz (e.g., about 300 kHz-1 GHz) and may denote auxiliary links e.g., used for wake-up signals and / or authentication signals and / or control signals.

[0042] As used herein, the term “IF passband” may relate to a specific range of intermediate frequencies (IF) that a receiver's bandpass filter is designed to pass while blocking others, allowing the desired signal to be separated, amplified, and processed without interference from adjacent channels or noise, that is the passband of the receiver’s IF chain, e.g., the 3 dB passband of the receiver’s IF chain. The IF bandwidth, Bw is width of the IF passband e.g., 3 dB.

[0043] As used herein, “beat” may refer A difference in frequency between a signal template and the received signal. Conventionally, the beat is used to determine the range and / or velocity of a target based on an echo. In some embodiments of the current invention the beat will be used to detect a signal and / or define a narrow band communication channel.

[0044] As used herein, the terms the “intermediate frequency chain” and “IF chain” may relate to a series of electronic components in a receiver (e.g., superheterodyne receiver, etc.) which processes a radio frequency (RF) signal, such as, after it has been down-converted to a fixed, lower frequency. The IF chain may be a core part of the receiver's architecture, and / or may provide signal amplification and / or filtering.

[0045] As used herein, the terms “numerically controlled oscillator” or “NCO” may relate to a digital signal generator which creates a synchronous (i.e., clocked), discrete-time, discrete-valued representation of a waveform,

[0046] As used herein, the terms "advertise" or “advertising” may refer to a device proactively announcing its presence, capabilities, or routing information to other devices on the network.

[0047] As used herein, the term “link” may relate to a communication channel that connects two or more devices, allowing for the transmission and reception of data. A link may be a pathway established for data to travel from one point to another.

[0048] OVERVIEW

[0049] An aspect of some embodiments of the current invention relates to a system and method to communicate data between a plurality of independent electromagnetic devices is disclosed and described. Optionally, the plurality of independent electromagnetic devices may include at least two transceivers. Optionally, the transceiver may include electromagnetic wave transceivers, for example, a radiofrequency device, and / or a millimeter wave device (e.g., radar), and / or an optical device (e.g., lidar). Optionally, the transceivers may be designed to measure the distance to an object and / or relative velocity via reflected signals (e.g., Frequency Modulated Continuous Wave Doppler radar (FMCW)). Optionally, the transceivers may transmit chirp signals individually. Optionally, at least one transceiver may be dedicated to transmitting and / or receiving a signal unidirectionally. Optionally, at least one transceiver may be dedicated to transmitting and / or receiving a signal omnidirectionally. Optionally the electromagnetic signals may include Doppler radar and / or lidar. Optionally, electromagnetic signals may include multi-band interrogation signals.

[0050] Doppler Division Multiple Access (DDMA) is a technique that may be used in radars, particularly in Multiple-Input Multiple-Output (MEMO) radar systems.

[0051] In some embodiments, DDMA is used to separate signals from multiple antennas transmitting simultaneously in the Doppler (also called Slow Time) dimension. Optionally, DDMA may facilitate pairs of transmitters and receivers to communicate without interfering with each other in the same area.

[0052] When a radar transmits a sequence of pulses (e.g., chirps in the case of FMCW radars), the serial number of these pulses is called Doppler dimension or Slow Time.

[0053] In some embodiments, DDMA modulates the phase of the transmitted pulses of a specific transmit antenna so that the phase of each pulse equals the phase of the previous pulse plus some fixed increment. This effect is equivalent to that of a specific value of a physical Doppler effect would induce. The greater the phase increment the greater the Doppler shift. Pulses transmitted from the next transmitting antenna may be processed similarly except that a different phase increment may be used. This may induce a different value of pseudo-Doppler. The result is that each antenna’s pulse sequence occupies a unique Doppler offset band. This separation allows the radar to identify which signal came from which antenna, even if they are received simultaneously.

[0054] In some embodiments, we use DDMA to separate signals of multiple radars transmitting simultaneously at a receiving (properly synchronized) radar.

[0055] In some embodiments, we use DDMA to separate signals of multiple radars transmitting simultaneously and multiple radars receiving simultaneously, where each couple and / or group of transmitters and receivers using different Doppler shift, without interfering with other groups, allowing groups to communicate with each other simultaneously without interfering with each other.

[0056] In conventional radar and / or lidar, the transmitter and receiver are co-located. Optionally, the system may transmit a signal towards a target and receive an echo of its own signal, e.g., the signal is reflected back to the system by the target. Optionally, the clock of the transmitter and receiver may be automatically synchronized (it is the same clock, therefore, there is no need to synchronize the returned signal). Optionally, the distance to the target may be computed based on the time of travel of the echo and / or change in phase. Optionally, the echo may be shifted and / or offset in frequency with respect to the outgoing transmitted signal due to the Doppler effect, e.g., if the target is moving. Optionally, the system may be configured to search for the incoming signal over a frequency window (Doppler window) for a signal that is frequency offset to find the returning signal even though it is offset from the outgoing signal. Optionally, the speed of the target may be computed based on this frequency shift. Optionally, if the target is moving relative to the radar, the frequency of the reflected signal may be different from the transmitted signal (Doppler shift). Optionally, by measuring the Doppler shift, the radar may determine the target's relative velocity.

[0057] According to some embodiments, the system may include multiple radar and / or lidar transceivers. Optionally, the system may be configured to detect one or more signals. Optionally, the signal may be a chirp signal. Optionally, the transceivers may transmit chirp signals individually. Optionally, the radar and / or lidar transceivers may transmit and / or receive signals. Optionally, multiple radar and / or lidar transceivers may transmit and / or receive signals from each other. Optionally, Doppler offset, the frequency and / or phase and / or timing of the signals of the multiple radar and / or lidar transceivers may be synchronized. Optionally, the signals may be radar and / or lidar signals. Optionally, the system may be configured to synchronize the clocks of multiple radar and / or lidar signals. Optionally, the transceivers may be configured to measure the distance between them without reflection, once synchronized.

[0058] According to some embodiments, the system may make use of “off the shelf’ radar and / or lidar. Optionally, the system may include high band Doppler radar (e.g., about 80 GHz, etc.). Optionally, the system may not make use of the reflected signals. Optionally, the ability of the radar and / or lidar to search over a window of frequencies (the Doppler window) may be configured for other purposes. Optionally, a set of synchronized Doppler radars will communicate simultaneously on orthogonal Doppler offsets. For example, the set may contain multiple radars and / or groups of radars. There may be one or more ad hoc sets of radars communicating. For example, various radars may communicate location information with respect to one another. For example, a pair of synchronized radars may receive signals from one another (a first radar receiving the signal of a second radar) over a first Doppler offset to compute relative location while another pair of radars in the same vicinity receive signals from one another (a third radar receiving the signal of a fourth radar) over a second Doppler offset (orthogonal to the first Doppler offset) to compute relative location. Alternatively, or additionally, the second radar may communication and / or compute relative location with the third radar on the second Doppler offset.

[0059] According to some embodiments, the system may facilitate searching for the signal e.g., using the Doppler function of the radar and / or lidar which is intended to search for frequency shifts due to the Doppler effect of moving objects on the echo of a radar beam. Optionally, “off the shelf’ radar and / or lidar is not intended to communicate at high band (e.g., about 80 GHz frequency, etc.), and therefore does not have a protocol to detect a signal whose frequency and / or timing and / or phase may not be synchronized with the internal clock of the radar. Optionally, the system may be configured to synchronize the Doppler offset, frequency and / or timing and / or phase of two or more radar and / or lidar.

[0060] According to some embodiments, the system may be configured to assume that the plurality of radar and / or lidar are stationary in space. Optionally, the multiple stationary units may be located in a small space. Optionally, the small space may range between about 1 km2to about 5 km2, and / or about 5 km2to about 10 km2, and / or 10 km2to about 50 km2. Optionally, each unit may transmit over a narrowband. Optionally, each unit may transmit spread band chirps.

[0061] According to some embodiments, the system may facilitate communication amongst a plurality of FMCW Doppler radar units. Optionally, each unit may transmit over a one or more of a set of orthogonal Doppler offsets and / or narrow frequency bands. Optionally, various units may each be transmitting at a different Doppler offset (e.g., as in DDMA) time offsets (e.g., using TDMA) and / or frequency offsets (e.g., FDMA) within a shared band of the FMCW radar. Optionally, each unit may search for other units over a Doppler offset window, a frequency window and / or a moving window. Optionally, each unit may search for the signal of a transmitting unit using a moving search window (e.g., the Doppler window built for detecting a shift between an outgoing signal and its echo). Optionally, each unit may be configured for searching for a shift between two or more units.

[0062] According to some embodiments, two-way communication may be over the Doppler offset band of one or more of the transmitters. Optionally, the system may be configured to facilitate a number of units sharing an available band, e.g., a Doppler offset band, an FDMA wide radar band. Optionally, the system may be configured for Time Division Multiple Access (TDMA), e.g., units may limit the times of their transmissions. Optionally, the division of frequencies may be ad-hoc and / or controlled in a multilateral system and / or decided bilaterally. According to some embodiments, a first unit (e.g., a firing unit, etc.) may transmit a signal. Optionally, one or more second units (e.g., receiving units) may search for the signal over a range of frequencies (e.g., the exact clock rate of the transmission is not known). Optionally, the search may include use of a Doppler function of a radar and / or lidar to search over a window of bands. Optionally, the system may use a moving search window (e.g., the window may be moved up and / or down to increase the range of searched bands). Optionally, when the second unit receives the signal, the clock of the receiver unit may be synchronized to that of the first unit. Optionally, the second unit may send a response signal back to the first unit. Optionally, along with the response signal the second unit may send the time and phase on which the signal was received. Optionally, the first unit may receive the response signal and timing information from the second unit. Optionally, the units may then communicate. Advantageously, two or more radars and / or lidars may be synchronized with each other. Optionally, one of the units may delegate time slots in the shared narrowband. Optionally, there may be communication of occupied time and / or frequency and / or Doppler offset slots and / or warnings of occupied time and / or frequency and / or Doppler offset slots.

[0063] According to some embodiments, the system may be a multi-band interrogation signal system. Optionally, the system may be configured to transmit and / or receive two or more signals at different frequencies. Optionally, the bandwidths of the frequencies may be far apart. Optionally, the system may include separate antennas for each bandwidth. Optionally, the transceiver may transmit and / or receive signals having a frequency ranging between about 30 GHz to about 120 GHz, and / or between about 60 GHz to about 100 GHz, and / or between about 75 GHz to about 95 GHz, and / or between about 76 GHz to about 81 GHz. Optionally, the bandwidth of the high band transceiver may range between about 1 GHz to about 10 GHz and / or 10 GHz to 30 GHz, and / or between about 3 MHz to about 2 GHz, and / or between about between about 300 kHz to about 3 MHz, and / or between about 30 kHz to about 300 kHz, and / or between about 1 Hz to about 100 kHz. Optionally, the transmitters may include radar and / or lidar e.g., in the meter wave range (e.g., between 1 to 10 meters), the decimeter range (e.g., between 1 to 0.1 m) the millimeter wave range (e.g., from 1 to 100 mm) and / or the micrometer wave range (e.g., between 1 to 1000 pm) and / or in the nanometer wave range (e.g., between 1 to 1000 nm).

[0064] According to some embodiments, the signal may be pulsed, modulated, encoded and / or coded (e.g., encoding and / or coding may be changed to avoid enemy stealing the device and / or spoofing the signal, modulated pulses of any frequency, and / or of any kind of modulation,), modulated and / or non-modulated signals in changing frequencies, spread spectrum, etc. Optionally, the signals may include a digital modulation technique to divide the limited spectrum available, such as Doppler division multiple access (DDMA), time division multiple access (TDMA) and / or frequency division multiple access (FDMA). Optionally, such systems may make it difficult for an enemy to detect and / or locate friendly forces. Optionally, this may prevent and / or make it difficult for the enemy to spoof the signal (e.g., to prevent the enemy from fooling friendly forces into firing on the enemy). Optionally, additional data may be transmitted and / or received (e.g., encourage communication and / or share information between units, individual soldiers, command, etc.).

[0065] According to some embodiments, the system may include a multi-band transceiver with an adjustable search and / or adjustable transmission band. Optionally, the system may be configured for bilateral and / or multilateral synchronization. Optionally, the system may be configured for communicating bilaterally and / or multilaterally without interference over narrow bands. Optionally, the processor may include software configured to facilitate bilateral and / or multilateral band searching, and / or synchronization, and / or communication. Optionally, the processor may include software configured to reduce and / or prevent interference.

[0066] According to some embodiments, due to the need for rapid transmission and the ability to handle Doppler offsets, Doppler radars require significant physical resources. Optionally, a limited number of radars can operate in the same area without interference. Optionally, the plurality of units may be stationary. Optionally, since the units are stationary Doppler shift may not need to be considered. Optionally, the Doppler shift of existing units may be configured for multiple access of devices not designed to communicate and / or not designed for multiple access. Optionally, multiple units may transmit simultaneously without interfering with each other. Optionally, multiple units may be synchronized in small windows of time and / or frequency and / or Doppler offset. Optionally each signal in the same window may include various Doppler effects and / or times of the signals Optionally, the transmitted signals may be detected and / or processed at the same time. Optionally, multiple units may be located close together in a static environment.

[0067] Some embodiments relate to a method including a first unit (Ul) transmitting on a narrowband. Optionally, a second unit (U2) may search over a wideband. Optionally, U2 may locate a signal from Ul. Optionally, U2 may synchronize to the band of Ul. Optionally, U2 may initiate communication with U1 over the narrow signal. Optionally, U1 and U2 may communicate in limited time slots.

[0068] According to some embodiments, the first unit may be transmitting on a narrowband and the second may search over multiple narrow bands. Optionally, the signals may be limited to various time slots.

[0069] According to some embodiments, the system may facilitate synchronization. The system may be configured to include band-allocation mechanics. Optionally, a receiving unit may sweep a moving search window over a frequency and / or offset to detect a peer’s narrowband. Optionally, the narrowband may be detected by correlation against a chirp template. Optionally, a detection may be declared when correlation exceeds a threshold and / or the beat falls within the intermediate frequency passband. Optionally, upon detection, the band adjuster may tune the local synthesizer and / or a digital numerically controlled oscillator (NCO) and / or resampler. Tuning may continue until the frequency error is equal to and / or smaller than the smallest increment the receiver uses to tune the search. This may indicate that the correct frequency band has been found and / or is very close to the true frequency of the signal. Optionally, this process may be performed continuously for a set number of chirps. The frequency and phase stability criteria may be met for a consecutive series of measurement cycles (e.g., chirps). Optionally, the system's ability to distinguish between two closely spaced objects may be limited by its frequency resolution. Optionally, the number of consecutive chirps transmitted by the radar may set this minimum detectable frequency difference. Optionally, the bandwidth of the radar's chirp may be increased such that the signal sweeps over a wider range of frequencies. Optionally, the number of consecutive chirps transmitted may be increased.

[0070] According to some embodiments, the receiver and transmitter may be switched to the identified narrowband for two-way communication. Optionally, links may share a frequency spectrum via DDMA (distinct slow-time phase increments). Optionally, DDMA may be combined with time division multiple access (TDMA) and / or frequency division multiple access (FDMA). Optionally, a controller may assign one or more per-link parameters. Optionally, per-link parameters may include phase increment, time slot, sub-band, etc. Optionally, the sub-band allocation may be ad-hoc (handshake) and / or by a designated coordinator. Optionally, band collisions may cause random back-off and / or re-scan of a wideband. Optionally, back-off may reduce the rate, and / or frequency, and / or power of a transmitter and / or receiver. According to some embodiments, after link acquisition, peers exchange IDs, capability bits, and authentication (e.g., rolling code and / or message authentication code (MAC)). A linksetup message may convey the selected narrowband parameters (e.g., phase increment, time slot, sub-band, etc.). Optionally, the transceivers may advertise acquisition, e.g., by proactively announcing its presence, capabilities, or routing information to other devices on the network. Optionally, neighboring transceivers may overhear the exchange and / or update a local map of occupied resources. Optionally, missed acknowledgments may trigger exponential back-off and / or re-advertise and / or re-scan. Optionally, coding and / or hopping across Doppler shifts and / or time slots and / or frequency bands may reduce detectability and / or spoofing. Optionally, unauthenticated frames may be ignored.

[0071] In some embodiments, wideband refers to the broad spectrum of frequencies over which the system initially searches to detect potential signals from peer units. This broad frequency range is may accommodate the initial uncertainty in the exact frequency or timing of the peer's signal. The process involves sweeping a search window across this wideband, correlating received signals against a signal template, and identifying signals that match the expected characteristics. The intermediate frequency (IF) bandwidth (BIF) may define the range of frequencies that the receiver's bandpass filter can accept and process. For example, the IF bandwidth might be set to between 1 to 4 MHz and / or between 0.1 to 1 MHz and / or between 4 to 16 MHz, allowing the system to handle signals within this range effectively.

[0072] Once a signal is detected, the system transitions to narrowband operation. Narrowband refers to the specific, limited frequency range where the detected signal resides and may facilitate precise and efficient communication. Optionally, transition from wideband to narrowband operation involves retuning the local synthesizer or digital oscillator to reduce the frequency error (Af) to within a small acceptable range, such as the sweep step 8f (e.g., 10-100 kHz). For example, the retuning process may reduce the frequency to within the IF passband. Optionally, this facilitates accurate signal processing and / or reduces the likelihood of interference. The system may adjust the frequency error to remain within this narrow range for a set number of consecutive chirps (e.g., N may range between 4 to 16 and / or 2 to 4 and / or between 16 to 256). This may facilitate stable and reliable communication. This narrowband operation facilitates two-way communication and / or simultaneous links can be maintained without interference. In some embodiments, a moving search window dynamically sweeps across the wideband frequency range, adjusting for potential frequency offsets to locate the peer's narrowband signal. The search window's movement is optionally guided by the correlation results against the signal template. In some embodiments, detection is declared when the correlation exceeds a predefined threshold (T). The beat frequency, which is the difference between the received signal and the local oscillator, may be kept within the IF passband (e.g., | Af| <BIFI2 This may facilitate keeping the detected signal is within the receiver's acceptable frequency range, facilitating further processing and communication. In some embodiments, the sweep step, defined as 8f, represents the incremental frequency adjustment made during the retuning process to achieve frequency lock.

[0073] In some embodiments, the system may utilize Doppler-Division Multiple Access (DDMA) to manage simultaneous links within the narrowband. DDMA assigns distinct slow-time phase increments to different links, ensuring that each link occupies a unique Doppler offset. This technique can be combined with Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) to optimize spectrum sharing and minimize interference. A controller may assign per-link parameters, including phase increments (AcpD), time slots, and sub-bands, either ad-hoc via handshake or through a designated coordinator. Collisions between links may trigger random back-off and re-scan procedures, allowing the system to dynamically adjust and maintain efficient communication. Authentication mechanisms, such as rolling codes or message authentication codes (MACs), can further enhance security and reliability in the communication process.

[0074] Example 1 - Acceptance & tolerances.

[0075] The absolute value of the beat frequency (I Af|) may be limited to be less than or equal to half of the intermediate frequency (IF) bandwidth (BIF / 2). This may keep the received signal's frequency within the acceptable range for the receiver to process. In some cases, acquisition will hold when:

[0076] |Af|<BiF / 2;

[0077] Where:

[0078] I Af| is the beat frequency, which is the frequency difference between the incoming signal and the receiver's local oscillator. In a receiver, this "beat" may be a new signal created when the incoming signal is mixed with a reference signal. BIF is the bandwidth of the receiver's intermediate frequency (IF) filter. This filter is designed to pass a specific range of frequencies while blocking all others. The total width of this range is BIF.

[0079] The IF passband is the frequency range that the filter allows to pass. It is cantered around the IF, extending from -BIF / 2 to +BIF / 2.

[0080] It should be understood that the numerical examples and parameter values presented herein are illustrative and non-limiting, and that other values may be used depending on implementation requirements or design constraints.

[0081] APPLICATIONS

[0082] The system and method described herein may be applied to a wide variety of domains in which multiple electromagnetic transceivers operate within a confined area or in coordinated motion. Practical applications include, for example, dense radar and lidar networks, automotive short-range communication between vehicles and roadside units, industrial sensing arrays, and cooperative perception among autonomous platforms.

[0083] In some embodiments, the invention may facilitate drone-hive and swarm coordination. For example, multiple airborne or ground unit may act as both a sensor and a communication node, exchanging range, velocity, and situational awareness data with nearby peers using Doppler- Division Multiple Access (DDMA).

[0084] In some embodiments, the invention may be applied to cooperative robotics, infrastructure monitoring, and area-based situational awareness systems that require low-latency synchronization and / or interference-free operation among multiple radar or lidar unit

[0085] ADVANTAGES

[0086] The combination of Doppler-Division Multiple Access (DDMA) with Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) may facilitate simultaneous, communication among multiple transceivers within a shared spectrum and / or reduced interference. In some embodiments, parameters such as phase increment, time slot, and sub-band are assigned per line. For example, parameters may be assigned ad-hoc via handshake and / or through a coordinating device. Optionally, the system dynamically allocates spectrum resources.

[0087] For example, the adaptive sharing mechanism may reduce collisions, support scalable operation in dense deployments, enhance overall link stability and / or enhance overall link efficiency.

[0088] SPECIFIC EMBODIMENTS

[0089] Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and / or methods set forth in the following description and / or illustrated in the drawings and / or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

[0090] Reference is now made to the exemplary figures.

[0091] FIG. 1 is a flow diagram describing a method for communication between multiple stationary units, in accordance with an embodiment of the current invention. For example, in method 10, communication between multiple stationary units in a small space is initiated by Unit 1 transmitting 12 on a narrowband, e.g., Unit 1 continuously transmits a signal on the predetermined frequency. Unit 2 scans 14 on a wider band to find Unit l's signal. Unit 2 scans a wideband of frequencies e.g., Unit 2 scans a wide range of Doppler offsets to increase the chance of detection. Unit 2 detects 16 the signal from Unit 1, e.g., if Unit 2 detects a signal matching Unit l's expected characteristics, proceed to the next step. Unit 2 synchronizes 18 to Unit 1 by adjusting its band to match the narrowband of Unit 1 for effective communication. Communication may be initiated between the two units and / or among more than 2 units, e.g., Unit 2 may send a synchronization signal and / or acknowledgment to Unit 1 to ensure both units are synchronized and / or ready to communicate. The units begin two-way communication 20 on the narrowband. Optionally, the communication may be limited to one or more time slots and / or to a narrow frequency band and / or to a narrow Doppler offset band. Optionally, additional factors, such as signal strength, noise, and error correction mechanisms may be taken into account. Optionally, the location of a friendly unit may be confirmed by additional means, e.g., determining direct vs. multipath high frequency signals, radio communication, GPS location, etc. Optionally, the searched band may be shared with other units that may be simultaneously communicating on other narrow bands within the larger searched band. Alternatively, or additionally, the narrowband may be shared by multiple units. For example, multiple units on a shared Doppler band and / or a narrow frequency band and / or may avoid interference using TDMA.

[0092] FIG. 2 is a schematic diagram of multiple transmitters and receivers communicating in accordance with an embodiment of the current invention. In some embodiments, multiple transmitting units 22, 24, 26, 28, 30 (e.g., transmitters 1-5) are transmitting, each in a different band (e.g., a different Doppler offset band). The result is a complex combined signal 48. Multiple receiving units 32, 34, 36, 38, 40 (e.g., receivers 1-5) may operate concurrently. Each receiver may filter out a signal from one or more of the transmitters and / or use the signal for communication. For example, receiver 1 32 filters out the signal 42 of transmitter 2 24 and uses it to compute a relative location of transmitter 224 with respect to receiver 1 32. For example, receiver 3 36 filters out signal 44 of transmitter 2 24 and signal 46 of transmitter 3 26 and uses them to compute a relative location of transmitter 2 24 and transmitter 3 26 with respect to each other and / or with respect to receiver 3 36. For example, receiver 4 38 and receiver 5 40 filter out the signal 46 of transmitter 3 26 and uses it to compute a relative location of transmitter 3 26 with respect to the respective receiver. The different bands may be used for data communication between any grouping of units. Optionally, the groupings and / or synchronization and / or communication is ad- hoc. For example, some signals (e.g., signal 4 50) may not be received by any receiver.

[0093] Protocol & Security. After link acquisition, peers exchange IDs, capability bits, and authentication (e.g., rolling code and / or message authentication code (MAC)). A link-setup message may convey the selected narrowband parameters (e.g., phase increment, time slot, subband, etc.). Optionally, the transceivers may advertise acquisition, e.g., by proactively announcing its presence, capabilities, or routing information to other devices on the network. Optionally, neighboring transceivers may overhear the exchange and / or update a local map of occupied resources. Optionally, missed acknowledgments may trigger exponential back-off and / or readvertise and / or re-scan. Optionally, coding and / or hopping across Doppler shifts and / or time slots and / or frequency bands may reduce detectability and / or spoofing. Optionally, unauthenticated frames may be ignored.

[0094] FIG. 3 is a block diagram describing a system for communication between multiple stationary units, in accordance with an embodiment of the current invention. For example, system 52 may include multiple units with transceivers and / or transmitters and / or receivers. A unit may be equipped with a receiver, a transmitter and / or a transceiver 54. A transceiver, receiver and / or transmitter may be configured to search, receive and / or transmit over multiple bands. For example, the bands may include orthogonal Doppler offset bands. Optionally, a unit searches for targets within a wideband range and / or adjusts its transmission band accordingly. Each unit may include a processor 56 (e.g., central processing unit (CPU), microcontroller, etc.) and software. Processor 56 may include a communication module 58 and / or a searching module 60. The software may be configured for coordinating radar operations, and / or managing band allocation, and / or synchronization, and / or handling data processing, and / or communication. The processors may coordinate the operations of the multiple units. The processors may manage band allocation, ensuring that different units do not interfere with each other. The processors may handle data processing, and / or synchronization, and / or communication between the units. Each unit may include a band adjuster 62 configured to adjust the bands of the unit’s transmission band to match the received band for synchronization to facilitate bilateral and / or multilateral communication.

[0095] According to some embodiments, a transmitter in Unit 1 generates a signal on a narrowband. The signal is then transmitted through an antenna. The antenna in Unit 2 receives the transmitted signal. The antennas in both units play a significant role in signal strength and transmission range. The received signal is processed by the receiver. The synthesizer in Unit 2 analyses the received signal to determine the band of Unit l's transmission. It then adjusts its own band to match that of Unit 1. The synthesizer is crucial for ensuring that Unit 2 can receive and transmit on the same band as Unit 1. Once synchronized, Unit 2 can begin communicating with Unit 1 on the narrowband. Optionally, additional components, like filters, amplifiers, and modulation / demodulation circuitry, may be included to enhance signal quality and performance. The specific implementation details may vary depending on factors such as the application, transmission distance, and desired data rates.

[0096] FIG. 4 is a schematic diagram illustrating a moving search window, in accordance with some embodiments of the current invention. For example, the system may include a first unit (Ul) transmitting on a narrowband 64. Optionally, a second unit (U2) may search over a wideband 66 of frequencies to locate Ul’s narrowband 64. Optionally, U2 may locate a signal from Ul. Optionally, U2 may synchronize to the band of Ul. Optionally U2 may retune and / or initiate communication with Ul. Optionally, U2 may initiate communication with Ul over the narrow signal band. Optionally, Ul and U2 may communicate in limited time slots. In some embodiments, a moving window may be used to search for a signal from a transmitter whose clock is not necessarily synchronized with the receiver. For example, a window may cover an offset of 50 KHz from the base frequency (e.g., for a W-band radar with carrier ~ 76-81 GHz). Alternatively, or additionally, the window may cover an offset of between 0 to 100 KHz and / or between 100 KHz to 1 MHz and / or between 1 to 100 MHz and / or between 100 MHz to 1 GHz. For example, the window size may represent the range of frequencies in the Fourier transform. Optionally the window may be shifted (e.g., by shifting the reference frequency and / or changing the range of the FFT). Alternatively, or additionally, the range of the search may be limited by a band-pass filter which may be adjusted to move the window. The window center and / or step should maintain the frequency error within the IF acceptance band. Within the acceptance band, the frequency error is equal to and / or smaller than the smallest increment the receiver uses to tune the search. This may indicate that the correct frequency band has been found and / or is very close to the true frequency of the signal. Optionally, this process may be performed continuously for a set number of chirps. The frequency and phase stability criteria may be met for a consecutive series of measurement cycles (e.g., chirps).

[0097] FIG. 5 is a table of exemplary radar and lidar frequency / wavelength bands relevant to the searched / shared band, in accordance with some embodiments of the current invention. In some embodiments, the shared band and / or searched band of a transceiver of the current invention may operate within a radar frequency band and / or across several frequency bands, each designated for specific applications and characteristics. For example, the search and / or communication may be within the L band, ranging from 1 to 2 GHz and / or the S band, spanning from 2 to 4 GHz and / or the C band, with frequencies from 4 to 8 GHz, and / or the X band, which ranges from 8 to 12 GHz and / or the Ku band, covering 12 to 18 GHz, and / or the K band, extending from 18 to 27 GHz and / or the Ka band, from 27 to 40 GHz and / or the V band, which spans from 40 to 75 GHz, and / or the W band, from 75 to 110 GHz.

[0098] Alternatively, or additionally, the shared band and / or searched band of a transceiver of the current invention may operate within a lidar frequency band and / or across several frequency bands, each designated for specific applications and characteristics. For example, the transceiver may use a LiDAR (Light Detection and Ranging) band of various wavelengths in the optical spectrum. For example, the transceiver may search and / or communicate with a band of about 700 to 1550 nm. Alternatively, the transceiver may work around 532 nm, e.g., for applications such as in shallow underwater applications. Alternatively, or additionally, the transceiver may search and / or communicate within a shortwave infrared (SWIR) range, about 1400 to 2500 nm. In some embodiments, the transceiver may operate within a range of between 400 to 1550 nm.

[0099] FIG. 6 is a block diagram illustrating a system for multi-transceiver communication, in accordance with some embodiments of the current invention. For example, system 68 includes a plurality of independent electromagnetic transceivers configured to transmit frequency modulated continuous wave (FMCW) chirps and to receive peer signals, a receiver chain of each transceiver including an intermediate-frequency bandwidth, and control circuitry. Control circuitry may be configured to (i) sweep a moving search window over frequency and offset while correlating against a chirp template, (ii) detect a peer’s narrowband when correlation exceeds a threshold and the frequency error is less than or equal to the smallest increment the receiver uses to tune the search, (iii) retune a local synthesizer or digital oscillator to reduce the limit of the system's range resolution for a number of consecutive chirps, and (iv) establish two-way communication on the detected narrowband, wherein simultaneous links are separated using Doppler-Division Multiple Access (DDMA) with distinct slow-time phase increments. Optionally, the intermediate-frequency bandwidth ranges between about 1-4 MHz Optionally, the frequency error ranges between about 10-100 kHz. Optionally, the number of consecutive chirps ranges between about 4-16. Optionally, band allocation may be ad-hoc via handshake or by a coordinator device. Optionally, collisions may trigger random back-off and / or re-scan. Optionally, further comprising authentication using a rolling code and / or message authentication code. Optionally, Time Division Multiple Access (TDMA) time slots and Frequency Division Multiple Access (FDMA) sub-bands are combined with DDMA. Optionally, the transceivers are radar units operating in at least one of L, S, C, X, Ku, K, Ka, V, or W bands and / or lidar units operating at about 400-1550 nm.

[0100] FIG. 7 is a flow chart illustrating a method for communication among independent frequency modulated continuous wave (FMCW) units, in accordance with some embodiments of the current invention. For example, method 76 includes scanning 78 a wideband with a moving search window. Detecting 80 a peer’s narrowband within an intermediate frequency acceptance band. Retuning 82 to achieve a link with frequency lock. In some embodiments, a Doppler phase increment may be assigned to the link. In some embodiments, data is exchanged on the narrowband while multiple links continue within the wideband via distinct slow-time phase increments. Optionally, method 76 includes combining DDMA with time division multiple access (TDMA) and / or frequency division multiple access (FDMA). Optionally, the frequency modulated continuous wave (FMCW) unit is a radar or lidar. Optionally, the units are stationary within a small geographic area. Optionally, retuning 82 includes retuning a synthesizer and / or a digital resampler using a band adjuster to achieve lock. Optionally, method 76 includes establishing links across orthogonal Doppler offsets. Optionally, method 76 includes advertising occupied resources so neighboring units avoid interference. Optionally, advertising includes announcing at least one of a phase increment, time slot, and frequency.

[0101] In some embodiments, the retuning 82 process involves adjusting the local synthesizer or digital resampler using a band adjuster until the frequency offset is minimized for a consecutive number of chirps, facilitating stable communication. Optionally, the retuning 82 facilitates achieving frequency lock and / or establishing a reliable link for data exchange.

[0102] In some embodiments, the method further comprises exchanging data on the narrowband while coordinating multiple links via distinct slow-time phase increments. This coordination may be achieved through Doppler Division Multiple Access (DDMA), which assigns unique Doppler offsets to different links. Optionally, the process includes assigning a Doppler phase increment to the link. Optionally, each link occupies a distinct Doppler offset.

[0103] Alternatively or additionally, the method may combine DDMA with Time Division Multiple Access (TDMA) or Frequency Division Multiple Access (FDMA). This combination facilitates efficient use of the available spectrum, allowing multiple units to communicate simultaneously with reduced interference.

[0104] In some embodiments, the frequency modulated continuous wave (FMCW) unit may be a radar or lidar. These units may be designed to measure the distance to an object and relative velocity via reflected signals. Optionally, the retuning 82 process includes retuning a synthesizer and / or a digital resampler using a band adjuster to achieve lock.

[0105] In some embodiments, the units may be stationary within a small geographic area. This stationary configuration may facilitate stable communication among the units. Optionally, the multiple links may be established across orthogonal Doppler offsets, facilitating that each link occupies a unique Doppler offset band.

[0106] In some embodiments, the method further comprises advertising occupied resources so neighboring units avoid interference. This advertising may include announcing at least one of a phase increment, time slot, and frequency. This proactive communication helps manage the shared spectrum and reduces the likelihood of collisions.

[0107] In some embodiments, the method may be implemented using a non-transitory computer- readable medium storing instructions that, when executed by control circuitry of a transceiver, result in the performance of the method. This implementation ensures that the method can be reliably executed by the control circuitry, facilitating efficient communication among the FMCW units.

[0108] The disclosed method leverages known technology of FMCW radar and lidar, utilizing high-band frequencies for radar / lidar and low-band frequencies for auxiliary links. Doppler Division Multiple Access (DDMA) assigns distinct slow-time phase increments to different links, ensuring each occupies a unique Doppler offset. The moving search window procedure sweeps frequency / offset to acquire a peer’s narrowband despite unknown clock / offset, facilitating reliable communication among the units.

[0109] In some embodiments, the system may include multiple radar and / or lidar transceivers configured to detect one or more signals, such as chirp signals. Optionally, the transceivers may transmit chirp signals individually and may be dedicated to transmitting and / or receiving signals unidirectionally or omnidirectionally. The system may facilitate communication among a plurality of FMCW Doppler radar units, each transmitting over a set of orthogonal Doppler offsets, time offsets, and / or frequency offsets within a shared band.

[0110] In some embodiments, the system may facilitate searching for signals using the Doppler function of the radar and / or lidar, which is intended to search for frequency shifts due to the Doppler effect of moving objects. Optionally, the system may be configured to synchronize the Doppler offset frequency, timing, and phase of two or more radar and / or lidar units, facilitating stable communication among the units.

[0111] In some embodiments, the system may assume that the plurality of radar and / or lidar units are stationary in space, located in a small geographic area. This stationary configuration may facilitate communication among the units without considering Doppler shift due to movement. Optionally, the system may facilitate communication among multiple units sharing an available band, using techniques such as TDMA and FDMA to avoid interference.

[0112] In some embodiments, the system may include a multi-band transceiver with an adjustable search and / or transmission band, facilitating bilateral and / or multilateral synchronization and communication. The system may be configured to reduce and / or prevent interference, ensuring reliable communication among the units.

[0113] In some embodiments, the system may be configured for rapid transmission and the ability to handle Doppler offsets, requiring significant physical resources. Optionally, the system may facilitate communication among multiple units located close together in a static environment, ensuring efficient use of the available spectrum.

[0114] FIG. 8 is a block diagram illustration of a system for multi-transceiver communication, in accordance with an embodiment of the current invention. Multiple receiver system 98, comprises a plurality of independent electromagnetic transceivers, including a receiving transceiver 90 and a peer transceiver 70. Each transceiver is configured to transmit signals and receive peer signals. The system includes a receiving receiver chain 92 and a peer receiver chain 72, each featuring an intermediate-frequency passband. Additionally, the system incorporates receiving control circuitry 94 and peer control circuitry 74, which are configured to manage various aspects of the communication process. In some embodiments, the receiving control circuitry 94 facilitates the sweeping of a moving search window over frequency and offset while correlating against a signal template. This process aids in detecting a peer’s narrowband when correlation exceeds a threshold and the frequency error is less than or equal to a specified threshold. Upon detection, the control circuitry may retune the local receiver and transmitter to increase agreement with the detected narrowband, thereby establishing two-way communication on the detected narrowband.

[0115] In some embodiments, the system supports simultaneous communication links within a wideband, separated using Doppler-Division Multiple Access (DDMA) with distinct slow-time phase increments. This technique assigns unique Doppler offsets to different links, allowing multiple transceivers to communicate without interference. The retuning process may include adjusting a synthesizer or a digital oscillator to achieve frequency alignment. Furthermore, retuning may reduce the limit of range resolution for a number of consecutive signals, enhancing the precision of communication. The system may utilize various signal types, including sweep signals, chirps, and Frequency -Modulated Continuous Wave (FMCW) signals. The intermediatefrequency passband may have a bandwidth of for example approximately 1 to 4 MHz and / or ranging between 10 to 12 MHz and / or between 12 to 16 MHz and / or ranging between 1 to 10 MHz and / or ranging between 16 to 30 MHz. In some embodiments, the frequency error may range between 10 to 100 kHz and / or between 1 to 10 kHz and / or between 100 kHz to 1 MHz. In some embodiments, the number of consecutive signals for retuning ranges between about 4 to 16 and / or between 1 to 4 and / or between 16 to 50.

[0116] The multiple receiver system 98 may facilitate band allocation in an ad-hoc manner via handshake or through a coordinator device. In scenarios where collisions occur, the system may trigger a random back-off and re-scan process to mitigate interference. Additionally, the system may incorporate authentication mechanisms using a rolling code or message authentication code to enhance security. The combination of Time Division Multiple Access (TDMA) time slots and Frequency Division Multiple Access (FDMA) sub-bands with DDMA may further optimize the communication process.

[0117] The transceivers within the multiple receiver system 98 may operate as radar units in various frequency bands, including L, S, C, X, Ku, K, Ka, V, or W bands, or as lidar units operating at wavelengths around 400-1550 nm. The threshold for detecting a peer’s narrowband may be less than or equal to the smallest increment the receiver uses to tune the search. This configuration ensures precise and efficient communication between the transceivers.

[0118] In some embodiments, the system may include a peer receiver system 68, comprising a peer transceiver 70, peer receiver chain 72, and peer control circuitry 74. The peer receiver system 68 may operate in conjunction with the receiving transceiver 90 to establish and maintain communication links. The peer control circuitry 74 may perform similar functions as the receiving control circuitry 94, including sweeping a moving search window, detecting narrowbands, retuning, and establishing two-way communication.

[0119] The multiple receiver system 98 may also support additional features such as advertising occupied resources to neighboring units to avoid interference. This proactive approach enhances the overall efficiency and reliability of the communication network. The system may utilize coding and hopping across Doppler, time, and frequency domains to reduce detectability and spoofing risks, ensuring secure and robust communication.

[0120] In some embodiments, the system may include a non-transitory computer-readable medium storing instructions that, when executed by the control circuitry, cause the performance of the described communication method. This method involves scanning a wideband with a moving search window, detecting a peer’s narrowband within an intermediate- frequency acceptance band, retuning to achieve frequency lock, assigning a Doppler phase increment to the link, and exchanging data on the narrowband while coordinating multiple links via DDMA, optionally combined with TDMA and / or FDMA.

[0121] The system's architecture may include various components such as filters, amplifiers, and modulation / demodulation circuitry to enhance signal quality and performance. The specific implementation details may vary depending on factors such as the application, transmission distance, and desired data rates. The system's flexibility and adaptability make it suitable for a wide range of applications, including radar and lidar communication in various frequency bands.

[0122] These embodiments are provided by way of example and are in no means intended to limit the scope of the invention.

[0123] While the invention has been described in its preferred form or embodiment with some degree of particularity, it is understood that this description has been given only by way of example and that numerous changes in the details of construction, fabrication, and use, including the combination and arrangement of parts, may be made without departing from the spirit and scope of the invention.

[0124] EXAMPLE

[0125] Reference is now made to the following example, which together with the above descriptions illustrate an embodiment of the invention in a non limiting fashion.

[0126] In an exemplary Synchronization & Band-Allocation system a receiving unit optionally sweeps a moving search window over frequency / offset to detect a peer’s narrowband by correlating against a chirp template; a detection is declared when correlation exceeds threshold T and the beat falls within the IF passband (e.g., abs(Af) < Bn? / 2). Upon detection, the band adjuster tunes the local synthesizer (or digital NCO / resampler) until abs(Af) < 8f for N consecutive chirps, then switches the receiver and transmitter to the identified narrowband for two-way communication. Links share spectrum via DDMA (distinct slow-time phase increments), optionally combined with TDMA / FDMA. A controller assigns per-link parameters — phase increment AcpD, time slot, and sub-band — either ad-hoc (handshake) or by a designated coordinator. Collisions cause random back-off and re-scan. Typical values: BIF = 1-4 MHz, sweep step 5f = 10-100 kHz, N = 4-16. GENERAL

[0127] It is expected that during the life of a patent maturing from this application many relevant building technologies, artificial intelligence methodologies, computer user interfaces, image capture devices will be developed and the scope of the terms for design elements, analysis routines, user devices is intended to include all such new technologies a priori.

[0128] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and / or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

[0129] As will be appreciated by one skilled in the art, some embodiments of the present invention may be embodied as a system, method or computer program product. Accordingly, some embodiments of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, some embodiments of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon. Implementation of the method and / or system of some embodiments of the invention can involve performing and / or completing selected tasks manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of some embodiments of the method and / or system of the invention, several selected tasks could be implemented by hardware, by software or by firmware and / or by a combination thereof, e.g., using an operating system.

[0130] For example, hardware for performing selected tasks according to some embodiments of the invention could be implemented as a chip or a circuit. As software, selected tasks according to some embodiments of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In an exemplary embodiment of the invention, one or more tasks according to some exemplary embodiments of method and / or system as described herein are performed by a data processor, such as a computing platform for executing a plurality of instructions. Optionally, the data processor includes a volatile memory for storing instructions and / or data and / or a non-volatile storage, for example, a magnetic hard-disk and / or removable media, for storing instructions and / or data. Optionally, a network connection is provided as well. A display and / or a user input device such as a keyboard or mouse are Optionally, provided as well.

[0131] Any combination of one or more computer readable medium(s) may be utilized for some embodiments of the invention. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0132] A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband / or as part of a carrier wave. Such a propagated signal may take any of a variety of forms including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer readable medium and / or data used thereby may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0133] Computer program code for carrying out operations for some embodiments of the present invention may be written in any combination of one or more programming languages, including an object-oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0134] Some embodiments of the present invention may be described below with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention.

[0135] It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0136] These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function / act specified in the flowchart and / or block diagram block or blocks. The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0137] Data and / or program code may be accessed and / or shared over a network, for example the Internet. For example, data may be shared and / or accessed using a social network. A processor may include remote processing capabilities, for example available over a network (e.g., the Internet). For example, resources may be accessed via cloud computing. The term “cloud computing” refers to the use of computational resources that are available remotely over a public network, such as the internet, and that may be provided for example at a low cost and / or on an hourly basis. Any virtual or physical computer that is in electronic communication with such a public network could potentially be available as a computational resource. To provide computational resources via the cloud network on a secure basis, computers that access the cloud network may employ standard security encryption protocols such as SSL and PGP, which are well known in the industry.

[0138] Some of the methods described herein are generally designed only for use by a computer and may not be feasible or practical for performing purely manually, by a human expert. A human expert who wanted to manually perform similar tasks might be expected to use completely different methods, e.g., making use of expert knowledge and / or the pattern recognition capabilities of the human brain, which would be vastly more efficient than manually going through the steps of the methods described herein.

[0139] As used herein the term “about” refers to ± 10%.

[0140] The terms "comprises", "comprising", "includes", "including", “having” and their conjugates mean "including but not limited to".

[0141] The term “consisting of’ means “including and limited to”.

[0142] The term "consisting essentially of' means that the composition, method or structure may include additional ingredients, steps and / or parts, but only if the additional ingredients, steps and / or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

[0143] As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise.

[0144] As used herein, the terms “plurality”, “multiple” and “multi” are used interchangeably, and mean two or more, e.g., 2, 3, 4, 5, 10, 20, etc.

[0145] Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0146] Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging / ranges between” a first indicate number and a second indicate number and “ranging / ranges from” a first indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween.

[0147] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements. Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

[0148] All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting.

Claims

CLAIMSWhat is claimed is:

1. A system for multi-transceiver communication comprising: a plurality of independent electromagnetic transceivers configured to transmit frequency modulated continuous wave (FMCW) chirps and to receive peer signals; a receiver chain of each transceiver including an intermediate-frequency bandwidth; and control circuitry configured to:(i) sweep a moving search window over frequency and offset while correlating against a chirp template;(ii) detect a peer’s narrowband when correlation exceeds a threshold and a frequency error is less than or equal to the smallest increment the receiver uses to tune the search;(iii) retune a local synthesizer or digital oscillator to reduce a limit of a range resolution of the system for a number of consecutive chirps; and(iv) establish two-way communication on the detected narrowband, wherein simultaneous links are separated using Doppler-Division Multiple Access (DDMA) with distinct slow-time phase increments.

2. A system for multi-transceiver communication comprising: a plurality of independent electromagnetic transceivers configured to transmit signals and to receive peer signals; a receiver chain of each transceiver including an intermediate-frequency passband; and control circuitry configured for:(i) sweeping a moving search window over frequency and offset while correlating against a signal template;(ii) detecting a peer’s narrowband when correlation exceeds a threshold and a frequency error is less than or equal to a threshold;(iii) retuning a local receiver and transmitter to increase agreement with the detected narrow band; and(iv) establishing two-way communication on the detected narrowband.

3. The system of claim 2, wherein communication occurs on simultaneous links within the wideband and the simultaneous links are separated using Doppler-Division Multiple Access (DDMA) with distinct slow-time phase increments.

4. The system of claim 2, wherein said retuning includes retuning a synthesizer or a digital oscillator.

5. The system of claim 2, wherein said retuning reduces a limit of a range resolution for a number of consecutive signals.

6. The system of claim 2, wherein said signal includes a sweep signal.

7. The system of claim 6, wherein said signal includes a chirp.

8. The system of claim 6, wherein the signal is a FMCW signal.

9. The system of claim 2, wherein the intermediate-frequency passband has a bandwidth ranging between 1-4 MHz.

10. The system of claim 2, wherein the frequency error ranges between 10-100 kHz.

11. The system of claim 5, wherein the number of consecutive signals ranges between about 4- 16.

12. The system of claim 2, wherein band allocation is ad-hoc via handshake.

13. The system of claim 2, wherein band allocation is by a coordinator device.

14. The system of claim 2, wherein collisions trigger random back-off and re-scan.

15. The system of claim 2, further comprising authentication using a rolling code or message authentication code.

16. The system of claim 2, wherein Time Division Multiple Access (TDMA) time slots and Frequency Division Multiple Access (FDMA) sub-bands are combined with DDMA.

17. The system of claim 2, wherein the transceivers are radar units operating in at least one of L, S, C, X, Ku, K, Ka, V, or W bands.

18. The system of claim 2, wherein the transceivers are lidar units operating at about 400-1550 nm.

19. The system of claim 2, wherein the threshold is less than or equal to the smallest increment the receiver uses to tune the search.

20. A method for communication among independent frequency modulated continuous wave (FMCW) units, the method comprising: scanning a wideband with a moving search window;detecting a narrowband of a peer within an intermediate frequency acceptance band of the search window; retuning to achieve a link with frequency lock.

21. The method of claim 20, further comprising: exchanging data on the narrowband while coordinating multiple links via distinct slow-time phase increments.

22. The method of claim 20, further comprising: assigning a Doppler phase increment to the link.

23. The method of claim 20, further comprising combining DDMA with time division multiple access (TDMA).

24. The method of claim 20, further comprising combining DDMA with frequency division multiple access (FDMA).

25. The method of claim 20, wherein the frequency modulated continuous wave (FMCW) unit is a radar or lidar.

26. The method of claim 20, further wherein the retuning includes retuning a synthesizer and / or a digital resampler using a band adjuster to achieve lock.

27. The method of claim 20, wherein units are stationary within a small geographic area.

28. The method of claim 21, wherein said multiple links are across orthogonal Doppler offsets.

29. The method of claim 20, further comprising advertising occupied resources so neighboring units avoid interference.

30. The method of claim 29, wherein the advertising includes announcing at least one of a phase increment, time slot, and frequency.

31. A non-transitory computer-readable medium storing instructions that, when executed by control circuitry of a transceiver, results in performance of the method of claim 20.

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