Patent Description:
Some challenges include size and layout constraints of the consumer device. These constraints can place restrictions on a radar's design. An example restriction can limit the quantity of antennas to decrease a footprint of the radar. The use of fewer antennas, however, can decrease the radar's sensitivity (e.g., ability to detect small objects or objects at far ranges) and angular resolution. Space constraints can also limit where the radar can be placed relative to other components within the electronic device. In some cases, these components generate interference, which can increase the radar system's false-alarm rate.

Other challenges involve power constraints within small or mobile consumer devices. Operation of some radars can significantly drain a battery of a consumer device and cause a user to frequently recharge the consumer device. Consequently, advantages of utilizing the radar may not be realized with the effective operation of the radar curtailed or disabled due to limitations of available power. A gesture detection system and a method using a radar sensor is disclosed in <CIT>. In <CIT> techniques and apparatuses that enable low-power radar are described. <CIT> discloses a smartphone-based radar system for facilitating awareness of user presence and orientation. <CIT> discloses a smartphone-based radar system capable of detecting user gestures using coherent multi-look radar processing.

The proposed solution relates to a method as stated in claim <NUM> of the accompanying claim set and an apparatus as stated in claim <NUM>. Techniques and apparatuses are described that implement a multi-radar system within a device and optimizes operation of the multi-radar system. The multi-radar system includes two or more radar circuits. The radar circuits are distributed on the device at different positions. Each radar circuit includes at least one antenna and at least one transceiver. At least a portion of an antenna pattern of a first radar circuit can overlap an antenna pattern of a second radar circuit. By partitioning the antennas and transceivers across multiple radar circuits instead of consolidating into a single integrated circuit, the radar circuits can have a smaller footprint than the single integrated circuit. This smaller footprint enables the radar circuits to be integrated within space-constrained devices, which are more likely to have multiple smaller spaces available than a single large space. The smaller footprint also provides additional flexibility in positioning the radar circuits away from other components within the device that can cause interference. This can reduce the amount of interference seen by the multi-radar system. The radar data generated by the transceivers of the radar circuits can be processed individually by respective processors of the radar circuits or combined in a coherent or non-coherent manner by a shared processor.

There can be some challenges to operating the multiple radar circuits, such as in a same operational state. For example, operating all of the radar circuits in a similar manner can significantly increase power consumption of the multi-radar system and limit the battery life of a device. Additionally, some radar circuits can have different levels of performance depending on their position and the relative location of a detected object (e.g., user). Furthermore, different operational states can be optimal for different types of radar-based applications, such as presence detection, gesture recognition, vital-sign detection, collision avoidance, and so forth.

To address these challenges, the multi-radar system includes an optimization controller, which selectively controls respective operational states of the radar circuits. In particular, the optimization controller can determine operational states of the radar circuits to optimize performance of the multi-radar system under certain constraints. Example types of performance that can be optimized include signal-to-noise ratio (SNR) performance, angular estimation, or an F-score (e.g., recall and precision). Example constraints include power consumption, signal clipping (e.g., saturation), or interference. The optimization controller can determine different operational states for different radar circuits based on respective positioning of the radar circuits in a device and based on a current operating environment of the device (e.g., amount of available power within the device, an orientation of the device, an active radar-based application, or presence of a single user or multiple users). In this way, the optimization controller can selectively alter the operational states of the radar circuits for various situations to optimize performance of the multi-radar system.

Aspects below include a method performed by a multi-radar system implemented within a device. The multi-radar system comprises two or more radar circuits, which are at different positions on the device. The method comprises causing a first radar circuit of the two or more radar circuits to be in a first operational state and causing a second radar circuit of the two or more radar circuits to be in a second operational state. The method also comprises detecting a trigger event that represents a change in an operating environment of the multi-radar system. Responsive to detecting the trigger event, the method further comprises selectively altering operation of at least one of the first radar circuit or the second radar circuit. The selective altering comprises at least one of: causing the first radar circuit to be in a third operational state that is different than the first operational state or causing the second radar circuit to be in a fourth operational state that is different than the second operational state.

Aspects described below also include an apparatus comprising a multi-radar system. The multi-radar system comprises two or more radar circuits and a controller. The multi-radar system is configured to perform any of the methods described herein.

Aspects described below also include a means for optimizing operation of a multi-radar system.

Apparatuses and techniques for optimizing operation of a multi-radar system are described with reference to the following drawings. The same numbers are used throughout the drawings to reference like features and components:.

Integrating a radar system within a consumer device can be challenging. One such challenge involves size or layout constraints of the consumer device. To fit within an available space of the consumer device, a radar system can be implemented with fewer antennas to decrease the radar system's footprint. The use of fewer antennas, however, can decrease the radar system's sensitivity (e.g., ability to detect small objects or objects at far ranges) and angular resolution.

The size or layout constraints can also limit where the radar system can be placed relative to other components within the consumer device. In some cases, these components generate emissions or cause vibrations, which can interfere with the radar system. This interference can include, for instance, vibrations caused by an audible sound produced by a speaker of the consumer device or a wireless communication signal transmitted by a wireless transceiver of the consumer device.

Another challenge involves power constraints within small or mobile consumer devices. Operation of some radars can significantly drain a battery of a consumer device and cause a user to frequently recharge the consumer device. Consequently, advantages of utilizing the radar may not be realized with the effective operation of the radar curtailed or disabled due to limitations of available power.

To address these challenges, this document describes techniques and devices for implementing a multi-radar system and optimizing operation of the multi-radar system. The multi-radar system includes two or more radar circuits. The radar circuits are distributed on the device at different positions. Each radar circuit includes at least one antenna and at least one transceiver. At least a portion of an antenna pattern of a first radar circuit overlaps an antenna pattern of a second radar circuit. By partitioning the antennas and transceivers across multiple radar circuits instead of consolidating into a single integrated circuit, the radar circuits can have a smaller footprint than the single integrated circuit. This smaller footprint enables the radar circuits to be integrated within space-constrained devices, which are more likely to have multiple smaller spaces available than a single large space. The smaller footprint also provides additional flexibility in positioning the radar circuits away from other components within the device that can cause interference. This can reduce the amount of interference seen by the multi-radar system. The radar data generated by the transceivers of the radar circuits can be processed individually by respective processors of the radar circuits or combined in a coherent or non-coherent manner by a shared processor.

<FIG> is an illustration of example environments <NUM>-<NUM> to <NUM>-<NUM> in which techniques using, and an apparatus including, a multi-radar system <NUM> may be embodied. In the depicted environments <NUM>-<NUM> to <NUM>-<NUM>, the multi-radar system <NUM> of a user device <NUM> is capable of detecting one or more objects (e.g., users). The user device <NUM> is shown to be a smartphone in environments <NUM>-<NUM> to <NUM>-<NUM> and a smart vehicle in the environment <NUM>-<NUM>. In general, the user device <NUM> may, e.g., be a user device comprising a computer processor and computer-readable media.

In the environments <NUM>-<NUM> to <NUM>-<NUM>, a user performs different types of gestures, which are detected by the multi-radar system <NUM>. In some cases, the user performs a gesture using an appendage or body part. Alternatively, the user can also perform a gesture using a stylus, a hand-held object, a ring, or any type of material that can reflect radar signals.

In environment <NUM>-<NUM>, the user makes a scrolling gesture by moving a hand above the user device <NUM> along a horizontal dimension (e.g., from a left side of the user device <NUM> to a right side of the user device <NUM>). In the environment <NUM>-<NUM>, the user makes a reaching gesture, which decreases a distance between the user device <NUM> and the user's hand. The users in environment <NUM>-<NUM> make hand gestures to play a game on the user device <NUM>. In one instance, a user makes a pushing gesture by moving a hand above the user device <NUM> along a vertical dimension (e.g., from a bottom side of the user device <NUM> to a top side of the user device <NUM>). In the environment <NUM>-<NUM>, the user device <NUM> is stored within a purse, and the multi-radar system <NUM> provides occluded-gesture recognition by detecting gestures that are occluded by the purse.

The multi-radar system <NUM> can also recognize other types of gestures or motions not shown in <FIG>. Example types of gestures include a knob-turning gesture in which a user curls their fingers to grip an imaginary doorknob and rotate their fingers and hand in a clockwise or counter-clockwise fashion to mimic an action of turning the imaginary doorknob. Another example type of gesture includes a spindle-twisting gesture, which a user performs by rubbing a thumb and at least one other finger together. The gestures can be two-dimensional, such as those used with touch-sensitive displays (e.g., a two-finger pinch, a two-finger spread, or a tap). The gestures can also be three-dimensional, such as many sign-language gestures, e.g., those of American Sign Language (ASL) and other sign languages worldwide. Upon detecting each of these gestures, the user device <NUM> can perform an action, such as display new content, move a cursor, activate one or more sensors, open an application, and so forth. In this way, the multi-radar system <NUM> provides touch-free control of the user device <NUM>.

In the environment <NUM>-<NUM>, the multi-radar system <NUM> generates a three-dimensional map of a surrounding environment for contextual awareness. The multi-radar system <NUM> also detects and tracks multiple users to enable both users to interact with the user device <NUM>. The multi-radar system <NUM> can also perform vital-sign detection. In the environment <NUM>-<NUM>, the multi-radar system <NUM> monitors vital signs of a user that drives a vehicle. Example vital signs include a heart rate and a respiration rate. If the multi-radar system <NUM> determines that the driver is falling asleep, for instance, the multi-radar system <NUM> can cause the user device <NUM> to alert the user. Alternatively, if the multi-radar system <NUM> detects a life threatening emergency, such as a heart attack, the multi-radar system <NUM> can cause the user device <NUM> to alert a medical professional or emergency services. The user device <NUM> and the multi-radar system <NUM> are further described with respect to <FIG>.

<FIG> illustrates the multi-radar system <NUM> as part of the user device <NUM>. The user device <NUM> is illustrated with various non-limiting example devices including a desktop computer <NUM>-<NUM>, a tablet <NUM>-<NUM>, a laptop <NUM>-<NUM>, a television <NUM>-<NUM>, a computing watch <NUM>-<NUM>, computing glasses <NUM>-<NUM>, a gaming system <NUM>-<NUM>, a microwave <NUM>-<NUM>, and a vehicle <NUM>-<NUM>. Other devices may also be used, such as a home service device, a smart speaker, a smart thermostat, a security camera, a baby monitor, a Wi-Fi™ router, a drone, a trackpad, a drawing pad, a netbook, an e-reader, a home-automation and control system, a wall display, a virtual reality headset, and another home appliance. Note that the user device <NUM> can be wearable, non-wearable but mobile, or relatively immobile (e.g., desktops and appliances). The multi-radar system <NUM> can be used as a stand-alone radar system or used with, or embedded within, many different user devices <NUM> or peripherals, such as in control panels that control home appliances and systems, in automobiles to control internal functions (e.g., volume, cruise control, or even driving of the car), or as an attachment to a laptop computer to control computing applications on the laptop.

The user device <NUM> includes one or more computer processors <NUM> and one or more computer-readable medium <NUM>, which includes memory media and storage media. Applications and/or an operating system (not shown) embodied as computer-readable instructions on the computer-readable medium <NUM> can be executed by the computer processor <NUM> to provide some of the functionalities described herein. The computer-readable medium <NUM> also includes a radar-based application <NUM>, which uses data generated by the multi-radar system <NUM> to perform a function, such as presence detection, gesture-based touch-free control, collision avoidance for autonomous driving, human vital-sign notification, and so forth.

The user device <NUM> can also include a network interface <NUM> for communicating data over wired, wireless, or optical networks. For example, the network interface <NUM> may communicate data over a local-area-network (LAN), a wireless local-area-network (WLAN), a personal-area-network (PAN), a wire-area-network (WAN), an intranet, the Internet, a peer-to-peer network, point-to-point network, a mesh network, and the like. The user device <NUM> may also include a display (not shown).

The multi-radar system <NUM> includes two or more radar circuits <NUM>-<NUM> to <NUM>-N, where N represents a positive integer. The radar circuits <NUM> are individual circuits (e.g., separate integrated circuits), which can be positioned at different positions on the user device <NUM> (e.g., within an interior of the user device <NUM> or mounted to an exterior surface of the user device <NUM>). Each radar circuit <NUM> includes at least one antenna <NUM> and at least one transceiver <NUM> to transmit and/or receive radar signals. In some cases, the radar circuit <NUM> includes a single antenna <NUM> coupled to a single transceiver <NUM>, which can together transmit and receive radar signals to implement a pulse-Doppler radar. In other cases, the radar circuit <NUM> includes at least one antenna coupled to a transmitter of the transceiver <NUM> and at least one other antenna coupled to a receiver of the transceiver <NUM> to implement a continuous-wave radar. The antenna <NUM> can be circularly polarized, horizontally polarized, or vertically polarized. The antenna <NUM> can be implemented together with the transceiver <NUM> on a same integrated circuit or implemented separate from the integrated circuit that includes the transceiver <NUM>.

In some implementations, the radar circuit <NUM> includes multiple antennas <NUM>, which represent antenna elements of one or more antenna arrays. An antenna array enables the radar circuit <NUM> to use analog or beamforming techniques during transmission and/or reception to improve the sensitivity and angular resolution of the multi-radar system <NUM>. Consider an example in which the radar circuit <NUM> includes an antenna <NUM> for transmission, and multiple antennas <NUM>, which form receive antenna elements of an antenna array, for reception. The receive antenna elements can be positioned to form a one-dimensional shape (e.g., a line) or a two-dimensional shape (e.g., a rectangular arrangement, a triangular arrangement, or an "L" shape arrangement) for implementations that include three or more receive antenna elements. The one-dimensional shape enables the radar circuit <NUM> to measure one angular dimension (e.g., an azimuth or an elevation) while the two-dimensional shape enables the radar circuit <NUM> to measure two angular dimensions (e.g., both azimuth and elevation). An element spacing associated with the receive antenna elements can be less than, greater than, or equal to half a center wavelength of the radar signal.

The radar circuits <NUM>-<NUM> to <NUM>-N can individually or jointly form beams that are steered or un-steered, wide or narrow, or shaped (e.g., hemisphere, cube, fan, cone, cylinder). The steering and shaping can be achieved through analog beamforming or digital beamforming. In some implementations, at least a portion of the antennas <NUM> within the radar circuits <NUM>-<NUM> to <NUM>-N have, for instance, an un-steered omnidirectional radiation pattern or can produce a wide steerable beam to illuminate a large volume of space during transmission. To achieve target angular accuracies and angular resolutions, a remaining portion of the antennas <NUM> within the radar circuits <NUM>-<NUM> to <NUM>-N can be used to generate hundreds or thousands of narrow steered beams with digital beamforming during reception. In this way, the multi-radar system <NUM> can efficiently monitor an external environment and detect one or more users.

The transceiver <NUM> includes circuitry and logic for transmitting and/or receiving radar signals via the antenna <NUM>. Components of the transceiver <NUM> can include amplifiers, mixers, switches, analog-to-digital converters, digital-to-analog converters, or filters for conditioning the radar signals. The transceiver <NUM> also includes logic to perform in-phase/quadrature (I/Q) operations, such as modulation or demodulation. A variety of modulations can be used, including linear frequency modulations, triangular frequency modulations, stepped frequency modulations, or phase modulations. Alternatively, the transceiver <NUM> can produce radar signals having a relatively constant frequency or a single tone. The transceiver <NUM> can be configured to support continuous-wave or pulsed radar operations.

A frequency spectrum (e.g., range of frequencies) that the transceiver <NUM> uses to generate the radar signals can encompass frequencies between <NUM> and <NUM> gigahertz (GHz), between <NUM> and <NUM>, between <NUM> and <NUM>, between <NUM> and <NUM>, between <NUM> and <NUM>, or at approximately <NUM>. In some cases, the frequency spectrum can be divided into multiple sub-spectrums that have similar or different bandwidths. The bandwidths can be on the order of <NUM> megahertz (MHz), <NUM>, <NUM>, and so forth. Different frequency sub-spectrums may include, for example, frequencies between approximately <NUM> and <NUM>, <NUM> and <NUM>, or <NUM> and <NUM>. Although the example frequency sub-spectrums described above are contiguous, other frequency sub-spectrums may not be contiguous. To achieve coherence, multiple frequency sub-spectrums (contiguous or not) that have a same bandwidth may be used by the transceiver <NUM> to generate multiple radar signals, which are transmitted simultaneously or separated in time. In some situations, multiple contiguous frequency sub-spectrums may be used to transmit a single radar signal, thereby enabling the radar signal to have a wide bandwidth.

The radar circuits <NUM>-<NUM> to <NUM>-N can each include one or more system processors <NUM> and one or more system medium <NUM> (e.g., one or more computer-readable storage medium). The system processor <NUM> executes instructions stored within the system medium <NUM> to analyze information provided by the transceiver <NUM> and provide data from the radar-based application <NUM>. For example, the system processor <NUM> can perform Fourier Transform (FT) operations, perform presence detection, gesture recognition, collision avoidance, or vital-sign detection.

Although the system processor <NUM> and the system medium <NUM> is shown to be implemented within each radar circuit <NUM>-<NUM> to <NUM>-N, alternative implementations share the system processor <NUM> and the system medium <NUM> across two or more of the radar circuits <NUM>-<NUM> to <NUM>-N to implement a distributed radar system. The transceivers <NUM> of the radar circuits <NUM>-<NUM> to <NUM>-N are coupled to the shared system processor <NUM>, which combines the information provided by the transceiver <NUM> in a coherent or non-coherent manner. The system processor <NUM> can also compensate for differences in performance, position, or phase across the radar circuits <NUM>-<NUM> to <NUM>-N. In this way, the shared system processor <NUM> can increase a signal-to-noise ratio of the multi-radar system <NUM> to enable the multi-radar system <NUM> to achieve a similar detection range and volume coverage as a non-distributed radar system that is implemented on a single integrated circuit. This also enables the multi-radar system <NUM> to realize higher angular resolution and sensitivity compared to implementing a radar system with a single radar circuit.

The multi-radar system <NUM> also includes an optimization controller <NUM>, which can be implemented using hardware, software, firmware, or a combination thereof. The optimization controller <NUM> can include at least one processor and at least one computer-readable storage medium. The optimization controller <NUM> can be localized at one module or one integrated circuit chip, or can be distributed across multiple modules and chips. In various implementations, the optimization controller <NUM> can be implemented as part of at least one of the radar circuits <NUM>-<NUM> to <NUM>-N or the computer processor <NUM>. In an example implementation, the optimization controller <NUM> is integrated within the radar circuit <NUM>-<NUM>, which enables the radar circuit <NUM>-<NUM> and the other radar circuits <NUM>-<NUM> to <NUM>-N to have a master-slave relationship with the radar circuit <NUM>-<NUM> operating as the master and the other radar circuits <NUM>-<NUM> to <NUM>-N operating as slaves.

The optimization controller <NUM> dynamically determines operational states of each radar circuit <NUM>-<NUM> to <NUM>-N to customize performance of the multi-radar system <NUM> according to different operating environments. In particular, the optimization controller <NUM> can cause the radar circuits <NUM>-<NUM> to <NUM>-N to operate according to operational states that improve signal-to-noise ratio performance, improve angular estimation, or improve an F-score within given constraints, such as power consumption, signal clipping, or interference. The operational states of the radar circuits <NUM>-<NUM> to <NUM>-N are further described with respect to <FIG>. The optimization controller <NUM> is further described with respect to <FIG> and <FIG>.

The user device <NUM> can also include at least one sensor <NUM> and at least one power circuit <NUM>. The sensor <NUM> can include a gyroscope, an inertial sensor, an accelerometer, an infrared sensor, a camera, a global navigation satellite system, a magnetometer, a barometer, an ambient light sensor, and so forth. Generally, the sensor <NUM> measures environmental conditions. The power circuit <NUM> can include a battery, a wireless charging system, a power-management integrated circuit (PMIC), or some combination thereof. The power circuit <NUM> provides power to the components of the user device <NUM>, including the multi-radar system <NUM>. In some examples, the optimization controller <NUM> utilizes information provided by the sensor <NUM> or the power circuit <NUM> to determine operational states of the radar circuits <NUM>-<NUM> to <NUM>-N, as further described with respect to <FIG>. Operation of the multi-radar system <NUM> is further described with respect to <FIG> and <FIG>.

<FIG> illustrates an example operation of the multi-radar system <NUM>. In the depicted configuration, the multi-radar system <NUM> is implemented as a frequency-modulated continuous-wave radar. However, other types of radar architectures can be implemented, as described above with respect to <FIG>. In environment <NUM>, a user <NUM> is located at a particular slant range <NUM> from the multi-radar system <NUM>. To detect the user <NUM>, one or more of the radar circuits <NUM>-<NUM> to <NUM>-N transmit a radar transmit signal <NUM>. At least a portion of the radar transmit signal <NUM> is reflected by the user <NUM>. This reflected portion represents a radar receive signal <NUM>. One or more of the radar circuits <NUM>-<NUM> to <NUM>-N receive the radar receive signal <NUM> and process the radar receive signal <NUM> to extract data for the radar-based application <NUM>. As depicted, an amplitude of the radar receive signal <NUM> is smaller than an amplitude of the radar transmit signal <NUM> due to losses incurred during propagation and reflection.

The radar transmit signal <NUM> includes a sequence of chirps <NUM>-<NUM> to <NUM>-C, where C represents a positive integer greater than one. Each radar circuit <NUM> can transmit the chirps <NUM>-<NUM> to <NUM>-C in a continuous burst or transmit the chirps <NUM>-<NUM> to <NUM>-C as time-separated pulses, as further described with respect to <FIG>. A duration of each chirp <NUM>-<NUM> to <NUM>-C can be on the order of tens or thousands of microseconds (e.g., between approximately <NUM> microseconds (µs) and <NUM> milliseconds (ms)), for instance.

Individual frequencies of the chirps <NUM>-<NUM> to <NUM>-C can increase or decrease over time. In the depicted example, an example radar circuit <NUM> employs a two-slope cycle (e.g., triangular frequency modulation) to linearly increase and linearly decrease the frequencies of the chirps <NUM>-<NUM> to <NUM>-C over time. The two-slope cycle enables the radar circuit <NUM> to measure the Doppler frequency shift caused by motion of the user <NUM>. In general, transmission characteristics of the chirps <NUM>-<NUM> to <NUM>-C (e.g., bandwidth, center frequency, duration, and transmit power) can be tailored to achieve a particular detection range, range resolution, or doppler sensitivity for detecting one or more characteristics the user <NUM> or one or more actions performed by the user <NUM>.

At the radar circuit <NUM>, the radar receive signal <NUM> represents a delayed version of the radar transmit signal <NUM>. The amount of delay is proportional to the slant range <NUM> (e.g., distance) from the antenna <NUM> of the radar circuit <NUM> to the user <NUM>. In particular, this delay represents a summation of a time it takes for the radar transmit signal <NUM> to propagate from the radar circuit <NUM> to the user <NUM> and a time it takes for the radar receive signal <NUM> to propagate from the user <NUM> to the radar circuit <NUM>. If the user <NUM> and/or the radar circuit <NUM> is moving, the radar receive signal <NUM> is shifted in frequency relative to the radar transmit signal <NUM> due to the Doppler effect. In other words, characteristics of the radar receive signal <NUM> are dependent upon motion of the hand and/or motion of the radar circuit <NUM>. Similar to the radar transmit signal <NUM>, the radar receive signal <NUM> is composed of one or more of the chirps <NUM>-<NUM> to <NUM>-C.

The multiple chirps <NUM>-<NUM> to <NUM>-C enable the radar circuit <NUM> to make multiple observations of the user <NUM> over a predetermined time period. A radar framing structure determines a timing of the chirps <NUM>-<NUM> to <NUM>-C, as further described with respect to <FIG>.

<FIG> illustrates an example radar framing structure <NUM>. In the depicted configuration, the radar framing structure <NUM> includes three different types of frames. At a top level, the radar framing structure <NUM> includes a sequence of main frames <NUM>, which can be in the active state or the inactive state. Generally speaking, the active state consumes a larger amount of power relative to the inactive state. At an intermediate level, the radar framing structure <NUM> includes a sequence of feature frames <NUM>, which can similarly be in the active state or the inactive state. Different types of feature frames <NUM> include a pulse-mode feature frame <NUM> (shown at the bottom-left of <FIG>) and a burst-mode feature frame <NUM> (shown at the bottom-right of <FIG>). At a low level, the radar framing structure <NUM> includes a sequence of radar frames (RF) <NUM>, which can also be in the active state or the inactive state.

The radar circuit <NUM> transmits and receives a radar signal during an active radar frame <NUM>. In some situations, the radar frames <NUM> are individually analyzed for basic radar operations, such as search and track, clutter map generation, user location determination, and so forth. Radar data collected during each active radar frame <NUM> can be saved to a buffer after completion of the radar frame <NUM> or provided directly to the system processor <NUM> of <FIG>.

The radar circuit <NUM> analyzes the radar data across multiple radar frames <NUM> (e.g., across a group of radar frames <NUM> associated with an active feature frame <NUM>) to identify a particular feature. Example types of features include a particular type of motion, a motion associated with a particular appendage (e.g., a hand or individual fingers), and a feature associated with different portions of the gesture. To recognize a gesture performed by the user <NUM> during an active main frame <NUM>, the radar circuit <NUM> analyzes the radar data associated with one or more active feature frames <NUM>.

A duration of the main frame <NUM> may be on the order of milliseconds or seconds (e.g., between approximately <NUM> and <NUM> seconds (s)). After active main frames <NUM>-<NUM> and <NUM>-<NUM> occur, the radar circuit <NUM> is inactive, as shown by inactive main frames <NUM>-<NUM> and <NUM>-<NUM>. A duration of the inactive main frames <NUM>-<NUM> and <NUM>-<NUM> is characterized by a deep sleep time <NUM>, which may be on the order of tens of milliseconds or more (e.g., greater than <NUM>). In an example implementation, the radar circuit <NUM> turns off all of the active components (e.g., an amplifier, an active filter, a voltage-controlled oscillator (VCO), a voltage-controlled buffer, a multiplexer, an analog-to-digital converter, a phase-lock loop (PLL) or a crystal oscillator) within the transceiver <NUM> to conserve power during the deep sleep time <NUM>.

In the depicted radar framing structure <NUM>, each main frame <NUM> includes K feature frames <NUM>, where K is a positive integer. If the main frame <NUM> is in the inactive state, all of the feature frames <NUM> associated with that main frame <NUM> are also in the inactive state. In contrast, an active main frame <NUM> includes J active feature frames <NUM> and K-J inactive feature frames <NUM>, where J is a positive integer that is less than or equal to K. A quantity of feature frames <NUM> can be adjusted based on a complexity of the environment or a complexity of a gesture. For example, a main frame <NUM> can include a few to a hundred feature frames <NUM> (e.g., K may equal <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>). A duration of each feature frame <NUM> may be on the order of milliseconds (e.g., between approximately <NUM> and <NUM>).

To conserve power, the active feature frames <NUM>-<NUM> to <NUM>-J occur prior to the inactive feature frames <NUM>-(J+<NUM>) to <NUM>-K. A duration of the inactive feature frames <NUM>-(J+<NUM>) to <NUM>-K is characterized by a sleep time <NUM>. In this way, the inactive feature frames <NUM>-(J+<NUM>) to <NUM>-K are consecutively executed such that the radar circuit <NUM> can be in a powered-down state for a longer duration relative to other techniques that may interleave the inactive feature frames <NUM>-(J+<NUM>) to <NUM>-K with the active feature frames <NUM>-<NUM> to <NUM>-J. Generally speaking, increasing a duration of the sleep time <NUM> enables the radar circuit <NUM> to turn off components within the transceiver <NUM> that require longer start-up times.

Each feature frame <NUM> includes L radar frames <NUM>, where L is a positive integer that may or may not be equal to J or K. In some implementations, a quantity of radar frames <NUM> may vary across different feature frames <NUM> and may comprise a few frames or hundreds of frames (e.g., L may equal <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>). A duration of a radar frame <NUM> may be on the order of tens or thousands of microseconds (e.g., between approximately <NUM> and <NUM>). The radar frames <NUM> within a particular feature frame <NUM> can be customized for a predetermined detection range, range resolution, or doppler sensitivity, which facilitates detection of a particular feature or gesture. For example, the radar frames <NUM> may utilize a particular type of modulation, bandwidth, frequency, transmit power, or timing. If the feature frame <NUM> is in the inactive state, all of the radar frames <NUM> associated with that feature frame <NUM> are also in the inactive state.

The pulse-mode feature frame <NUM> and the burst-mode feature frame <NUM> include different sequences of radar frames <NUM>. Generally speaking, the radar frames <NUM> within an active pulse-mode feature frame <NUM> transmit pulses that are separated in time by a predetermined amount. This disperses observations over time, which can make it easier for the radar circuit <NUM> to recognize a gesture due to larger changes in the observed chirps <NUM>-<NUM> to <NUM>-C within the pulse-mode feature frame <NUM> relative to the burst-mode feature frame <NUM>. In contrast, the radar frames <NUM> within an active burst-mode feature frame <NUM> transmit pulses continuously across a portion of the burst-mode feature frame <NUM> (e.g., the pulses are not separated by a predetermined amount of time). This enables an active-burst-mode feature frame <NUM> to consume less power than the pulse-mode feature frame <NUM> by turning off a larger quantity of components, including those with longer start-up times, as further described below.

Within each active pulse-mode feature frame <NUM>, the sequence of radar frames <NUM> alternates between the active state and the inactive state. Each active radar frame <NUM> transmits a chirp <NUM> (e.g., a pulse), which is illustrated by a triangle. A duration of the chirp <NUM> is characterized by an active time <NUM>. During the active time <NUM>, components within the transceiver <NUM> are powered-on. During a short-idle time <NUM>, which includes the remaining time within the active radar frame <NUM> and a duration of the following inactive radar frame <NUM>, the radar circuit <NUM> conserves power by turning off one or more active components within the transceiver <NUM> that have a start-up time within a duration of the short-idle time <NUM>.

An active burst-mode feature frame <NUM> includes P active radar frames <NUM> and L-P inactive radar frames <NUM>, where P is a positive integer that is less than or equal to L. To conserve power, the active radar frames <NUM>-<NUM> to <NUM>-P occur prior to the inactive radar frames <NUM>-(P+<NUM>) to <NUM>-L. A duration of the inactive radar frames <NUM>-(P+<NUM>) to <NUM>-L is characterized by a long-idle time <NUM>. By grouping the inactive radar frames <NUM>-(P+<NUM>) to <NUM>-L together, the radar circuit <NUM> can be in a powered-down state for a longer duration relative to the short-idle time <NUM> that occurs during the pulse-mode feature frame <NUM>. Additionally, the radar circuit <NUM> can turn off additional components within the transceiver <NUM> that have start-up times that are longer than the short-idle time <NUM> and shorter than the long-idle time <NUM>.

Each active radar frame <NUM> within an active burst-mode feature frame <NUM> transmits a portion of the chirp <NUM>. In this example, the active radar frames <NUM>-<NUM> to <NUM>-P alternate between transmitting a portion of the chirp <NUM> that increases in frequency and a portion of the chirp <NUM> that decreases in frequency.

The radar framing structure <NUM> enables power to be conserved through adjustable duty cycles within each frame type. A first duty cycle <NUM> is based on a quantity of active feature frames <NUM> (J) relative to a total quantity of feature frames <NUM> (K). A second duty cycle <NUM> is based on a quantity of active radar frames <NUM> (e.g., L/<NUM> or P) relative to a total quantity of radar frames <NUM> (L). A third duty cycle <NUM> is based on a duration of the chirp <NUM> relative to a duration of a radar frame <NUM>.

Consider an example radar framing structure <NUM> for a power state that consumes approximately <NUM> milliwatts (mW) of power and has a main-frame update rate (e.g., frame rate) between approximately <NUM> and <NUM> hertz (Hz). An update rate or a frame rate represents a rate at which particular frames (e.g., the main frames <NUM>, the feature frames <NUM>, or the radar frames <NUM>) are scheduled. In this example, the radar framing structure <NUM> includes a main frame <NUM> with a duration between approximately <NUM> and <NUM> second. The main frame <NUM> includes thirty-one pulse-mode feature frames <NUM> (e.g., K is equal to <NUM>). One of the thirty-one pulse-mode feature frames <NUM> is in the active state. This results in the duty cycle <NUM> being approximately equal to <NUM>%. A duration of each pulse-mode feature frame <NUM> is between approximately <NUM> and <NUM>. Each pulse-mode feature frame <NUM> is composed of eight radar frames <NUM> (e.g., L is equal to <NUM>). Within the active pulse-mode feature frame <NUM>, all eight radar frames <NUM> are in the active state. This results in the duty cycle <NUM> being equal to <NUM>%. A duration of each radar frame <NUM> is between approximately <NUM> and <NUM>. An active time <NUM> within each of the active radar frames <NUM> is between approximately <NUM> and <NUM>. As such, the resulting duty cycle <NUM> is approximately <NUM>%. This example radar framing structure <NUM> can result in adequate near-range detection, gesture recognition, and presence detection while also conserving power. Generation of the radar transmit signal <NUM> (of <FIG>) and the processing of the radar receive signal <NUM> (of <FIG>) are further described with respect to <FIG>.

<FIG> illustrates an example radar circuit <NUM> of the multi-radar system <NUM>. In the depicted configuration, the radar circuit <NUM> implements a portion of a frequency-modulated continuous-wave radar. However, other types of radar architectures can be implemented, as described above with respect to <FIG>. The transceiver <NUM> of the radar circuit <NUM> includes at least one transmitter <NUM> and at least one receiver <NUM>. The transmitter <NUM> includes at least one voltage-controlled oscillator <NUM> and at least one power amplifier (PA) <NUM>. The receiver <NUM> includes one or more receive channels <NUM>-<NUM> to <NUM>-M, where M is a positive integer. Each receive channel <NUM>-<NUM> to <NUM>-M includes at least one low-noise amplifier (LNA) <NUM>, at least one mixer <NUM>, at least one filter <NUM>, and at least one analog-to-digital converter <NUM>.

The radar circuit <NUM> also includes multiple antennas <NUM>, which include at least one transmit antenna <NUM> and at least two receive antennas <NUM>-<NUM> to <NUM>-M. The transmit antenna <NUM> is coupled to the transmitter <NUM>. The receive antennas <NUM>-<NUM> to <NUM>-M form an antenna array, such as a linear antenna array, and are respectively coupled to the receive channels <NUM>-<NUM> to <NUM>-M. Although the radar circuit <NUM> of <FIG> is shown to include multiple receive antennas <NUM>-<NUM> to <NUM>-M and multiple receive channels <NUM>-<NUM> to <NUM>-M, other implementations can include a single receive antenna <NUM> and a single receive channel <NUM>.

During transmission, the voltage-controlled oscillator <NUM> generates a frequency-modulated radar signal <NUM> at radio frequencies. The frequency-modulated radar signal <NUM> can include a sequence of chirps. The chirps can be transmitted in a continuous burst or as time-separated pulses. A duration of each chirp can be on the order of tens or thousands of microseconds (e.g., between approximately <NUM> microseconds (µs) and <NUM> milliseconds (ms)), for instance.

Individual frequencies of the chirps can increase or decrease over time. As an example, the radar circuit <NUM> employs a two-slope cycle (e.g., triangular frequency modulation) to linearly increase and linearly decrease the frequencies of the chirps over time. The two-slope cycle enables the radar circuit <NUM> to measure the Doppler frequency shift caused by motion of an user (or object). In general, transmission characteristics of the chirps (e.g., bandwidth, center frequency, duration, and transmit power) can be tailored to achieve a particular detection range, range resolution, or doppler sensitivity for detecting one or more characteristics the user or one or more actions performed by the user.

During operation, the power amplifier <NUM> amplifies the frequency-modulated radar signal <NUM> for transmission via the transmit antenna <NUM>. The transmitted frequency-modulated radar signal <NUM> is represented by a radar transmit signal <NUM>. The radar circuit <NUM> receives and processes the radar receive signal <NUM>. In particular, each receive antenna <NUM>-<NUM> to <NUM>-M receives a version of the radar receive signal <NUM>-<NUM> to <NUM>-M. In general, relative phase differences between these versions of the radar receive signals <NUM>-<NUM> to <NUM>-M are due to differences in locations of the receive antennas <NUM>-<NUM> to <NUM>-M. Within each receive channel <NUM>-<NUM> to <NUM>-M, the low-noise amplifier <NUM> amplifies the radar receive signal <NUM>, and the mixer <NUM> mixes the amplified radar receive signal <NUM> with the frequency-modulated radar signal <NUM>. In particular, the mixer performs a beating operation, which downconverts and demodulates the radar receive signal <NUM> using the frequency-modulated radar signal <NUM> to generate a beat signal <NUM>.

A frequency of the beat signal <NUM> represents a frequency difference between the frequency-modulated radar signal <NUM> and the radar receive signal <NUM>, which is proportional to the slant range to the user. Although not shown, the beat signal <NUM> can include multiple frequencies, which represents reflections from different portions of the user (e.g., different fingers, different portions of a hand, or different body parts). In some cases, these different portions move at different speeds, move in different directions, or are positioned at different slant ranges relative to the radar circuit <NUM>.

The filter <NUM> filters the beat signal <NUM>, and the analog-to-digital converter <NUM> digitizes the filtered beat signal <NUM>. The receive channels <NUM>-<NUM> to <NUM>-M respectively generate digital beat signals <NUM>-<NUM> to <NUM>-M, which are provided to the system processor <NUM> for processing. The receive channels <NUM>-<NUM> to <NUM>-M of the transceiver <NUM> are coupled to the system processor <NUM>. Multiple instances of the radar circuit <NUM> can be implemented within the user device <NUM>, as further described with respect to <FIG>.

<FIG> illustrates example positions of the multi-radar system <NUM>'s radar circuits <NUM> on a smartphone <NUM>. In the depicted configuration, the smartphone <NUM> includes radar circuits <NUM>-<NUM> to <NUM>-<NUM>. In some implementations, the radar circuits <NUM>-<NUM> to <NUM>-<NUM> are positioned within or under an exterior housing of the smartphone <NUM>, which can be substantially transparent to radar signals (e.g., minimally attenuate radar signals).

The radar circuits <NUM>-<NUM> to <NUM>-<NUM> are positioned around the smartphone <NUM> such that a portion of each radar circuit <NUM>'s antenna pattern overlaps at least one other radar circuit <NUM>'s antenna pattern. In this way, an object can be detected in the overlapping antenna patterns of at least two of the radar circuits <NUM>-<NUM> to <NUM>-<NUM> at various locations around the smartphone <NUM>.

The one or more antennas <NUM> of each radar circuit <NUM> can face up along the Y axis towards an upper side of the smartphone <NUM>, face left along the X axis towards a left side of the smartphone <NUM>, face down along the Y axis towards a bottom side of the smartphone <NUM>, or face right along the X axis towards a right side of the smartphone <NUM>. For example, the antennas <NUM> of the radar circuits <NUM>-<NUM> and <NUM>-<NUM> can face up along the Y axis, the antennas <NUM> of the radar circuits <NUM>-<NUM> and <NUM>-<NUM> can face left along the X axis, the antennas <NUM> of the radar circuits <NUM>-<NUM> and <NUM>-<NUM> can face down along the Y axis, and the antennas <NUM> of the radar circuits <NUM>-<NUM> and <NUM>-<NUM> can face right along the X axis. In other implementations, the antennas <NUM> of one or more of the radar circuits <NUM>-<NUM> to <NUM>-<NUM> can face up out of the page along the Z axis towards a front face of the smartphone <NUM> or face down into the page along the Z axis towards a back side of the smartphone <NUM>.

Although the antennas <NUM> of the radar circuits <NUM>-<NUM> to <NUM>-<NUM> can face a particular side of the smartphone <NUM>, the antenna patterns of these antennas <NUM> can encompass a volume of space above the front face of the smartphone <NUM> and/or another volume of space behind the backside of the smartphone <NUM>. In this way, the radar circuits <NUM>-<NUM> to <NUM>-<NUM> can detect a user interacting with the smartphone <NUM>.

Some positions within or around the smartphone <NUM> can be better for detecting certain types of gestures performed by a user. In particular, these positions can increase a radar circuit <NUM>'s probability of detecting the user by increasing the radar circuit <NUM>'s signal-to-noise ratio. For example, some positions can increase the overlap between a radar circuit <NUM>'s antenna pattern and a region of interest in which the user is likely to perform gestures or interact with the smartphone <NUM>. The positions of the radar circuits <NUM>-<NUM> and <NUM>-<NUM>, for instance, can be better for detecting gestures by placing the radar circuits <NUM>-<NUM> and <NUM>-<NUM> closer to the user as the user holds the smartphone <NUM> in the depicted portrait orientation. Alternatively, the radar circuits <NUM>-<NUM> and <NUM>-<NUM> or the radar circuits <NUM>-<NUM> and <NUM>-<NUM> can be better positioned for detecting gestures if the user holds the smartphone <NUM> in a landscape orientation (not shown).

In some implementations, the radar circuits <NUM>-<NUM> to <NUM>-<NUM> have multiple antennas <NUM> that form an antenna array, such as multiple transmit antennas <NUM> or multiple receive antennas <NUM>. Consider an example in which the radar circuits <NUM>-<NUM> to <NUM>-<NUM> each include at least two receive antennas <NUM>-<NUM> and <NUM>-<NUM>, which form a linear antenna array. Orientations of these linear antenna arrays can vary to enable the multi-radar system <NUM> to determine two-dimensional angular information associated with an object. In particular, orientations of some linear antenna arrays can differ by approximately <NUM> degrees. For example, the receive antennas <NUM>-<NUM> and <NUM>-<NUM> of the radar circuit <NUM>-<NUM> can be aligned along the X axis to enable the multi-radar system <NUM> to measure azimuth angles of objects and the receive antennas <NUM>-<NUM> and <NUM>-<NUM> of the radar circuit <NUM>-<NUM> can be aligned along the Y axis to enable the multi-radar system <NUM> to measure elevation angles of objects.

Although the smartphone <NUM> of <FIG> is shown to include eight radar circuits <NUM>-<NUM> to <NUM>-<NUM>, other implementations of the smartphone <NUM> can have fewer radar circuits <NUM>. For example, the smartphone <NUM> can include two radar circuits <NUM>, such as radar circuits <NUM>-<NUM> and <NUM>-<NUM>. In some cases, the two radar circuits <NUM> are oriented along different axes to enable two-dimensional angular information to be determined. The radar circuits <NUM>-<NUM> to <NUM>-<NUM> can operate according to different operational states, which are further described with respect to <FIG>.

<FIG> illustrates an example operational state <NUM> of a radar circuit <NUM>. The operational state <NUM> can be associated with a transceiver configuration <NUM> and/or a processing configuration <NUM>. The transceiver configuration <NUM> represents a configuration of the radar circuit <NUM>'s transceiver <NUM>, which can affect characteristics of the radar transmit signal <NUM> and the radar receive signal <NUM>. For example, the transceiver configuration <NUM> can specify a particular transmit power <NUM> or amplifier gain <NUM>. In some cases, the transmit power <NUM> can vary based on a range or distance that the radar circuit <NUM> is monitoring. If the user <NUM> is farther from the user device <NUM>, for example, a higher transmit power <NUM> can be used to detect the user <NUM>. Alternatively, if the user <NUM> is closer to the user device <NUM>, a lower transmit power <NUM> can be used to conserve power. The amplifier gain <NUM> can enable a particular transmit power <NUM> by specifying the gain of the power amplifier <NUM> of <FIG>. In other cases, the amplifier gain <NUM> can specify a gain of the low-noise amplifier <NUM> of <FIG> or a gain of a variable gain amplifier within the transceiver <NUM> (not shown in <FIG>). Although increasing the amplifier gain <NUM> can improve sensitivity of the multi-radar system <NUM>, it can also increase a likelihood of signal clipping or saturation. This signal clipping can make it challenging for the multi-radar system <NUM> to accurately detect objects with large radar cross sections or objects at close ranges.

Additionally or alternatively, the transceiver configuration <NUM> can specify a particular radar framing structure <NUM> (e.g., the framing structure <NUM> of <FIG>) and/or a frame rate <NUM> of frames within the radar framing structure <NUM>. As described with respect to <FIG>, the radar framing structure <NUM> specifies scheduling and signal characteristics associated with the transmission and reception of the radar signals. In general, the radar framing structure <NUM> is selected to enable the appropriate radar data to be collected for the radar-based application <NUM>. The radar framing structure <NUM> can be customized to facilitate collection of different types of radar data for different applications (e.g., presence detection, feature recognition, or gesture recognition). The frame rate <NUM> represents the rate at which particular frames (e.g., the main frames <NUM>, the feature frames <NUM>, or the radar frames <NUM>) are scheduled within the radar framing structure <NUM>.

The transceiver configuration <NUM> can optionally specify a particular transmit frequency <NUM> or an analog-to-digital converter (ADC) sampling rate <NUM>. The transmit frequency <NUM> can include a center frequency and/or a bandwidth of the radar transmit signal <NUM>. Decreasing the transmit frequency <NUM> can reduce propagation loss and enable the radar circuit <NUM> to detect objects at farther ranges. In contrast, increasing the transmit frequency <NUM> can improve Doppler sensitivity of the radar circuit <NUM>. Increasing the ADC sampling rate <NUM> of the analog-to-digital converter <NUM> (of <FIG>) can increase the maximum detectable range of the radar circuit <NUM> at the cost of increasing power consumption. Other transceiver configurations <NUM> not shown can include a filter cut-off frequency, which can specify a passband of the filter <NUM> (of <FIG>).

The processing configuration <NUM> represents a configuration of the radar circuit <NUM>'s system processor <NUM> and the types of functions or operations it performs to analyze the radar receive signal <NUM>. Example processing configurations <NUM> can include range-Doppler map generation <NUM>, digital beamforming <NUM>, and/or machine learning <NUM>. For some radar-based applications <NUM>, such as presence detection, the range-Doppler map generation <NUM> can be used to detect an object and measure a range or range rate of the object. For other radar-based applications <NUM> that utilize angular information about the object, the processing configuration <NUM> can include digital beamforming <NUM> to measure the angular position of the object. The machine learning <NUM> can be used to perform gesture recognition, for instance. Various processing configurations <NUM> can utilize different amounts of memory or computational power, which in turn affects power consumption of the multi-radar system <NUM>.

Example operational states <NUM> include an off state <NUM>, a low-power state <NUM>, a high-power state <NUM>, a pre-gesture-detection state <NUM>, and a gesture-recognition state <NUM>. These operational states are further described with respect to <FIG>. The optimization controller <NUM>, which may determine or manage the operational states <NUM>, is further described with respect to <FIG> and <FIG>.

<FIG> illustrates the optimization controller <NUM> as part of the multi-radar system <NUM>. In the depicted configuration, the optimization controller <NUM> is coupled to the radar circuits <NUM>-<NUM> to <NUM>-N of the multi-radar system <NUM>. The optimization controller <NUM> can also be coupled to the sensor <NUM>, the power circuit <NUM>, and/or the computer processor <NUM> of the user device <NUM>.

During operation, the optimization controller <NUM> considers one or more operational variables <NUM> associated with the radar circuits <NUM>-<NUM> to <NUM>-N, one or more optimization parameters <NUM>, and one or more constraints <NUM> to determine the operational states <NUM>-<NUM> to <NUM>-N for the respective radar circuits <NUM>-<NUM> to <NUM>-N. The operational variables <NUM> describe characteristics of the radar circuits <NUM>-<NUM> to <NUM>-N, such as antenna patterns, noise figures, power consumption, and constant false-alarm rate (CFAR) thresholds. Other operational variables <NUM> can be related to the user device <NUM> or the environment, such as an orientation of the user device <NUM>, battery capacity of the user device <NUM>, or weather conditions (e.g., precipitation). Some operational variables <NUM> can be fixed, such as the antenna patterns, while others can vary over time, such as the orientation of the user device <NUM> or the weather.

The optimization parameter <NUM> represents a parameter that the optimization controller <NUM> can improve by tailoring the operational states <NUM>-<NUM> to <NUM>-N of the radar circuits <NUM>-<NUM> to <NUM>-N. Example optimization parameters <NUM> include signal-to-noise ratio performance (e.g., accuracy), angular estimation performance (e.g., accuracy of azimuth or elevation measurements), and an F-score (e.g., recall and precision). Other example optimization parameters <NUM> can include range resolution, Doppler resolution, coverage volume (e.g., a detectable range or angular field-of-view), responsiveness, or some combination thereof.

The constraint <NUM> represents a parameter that can impact the ability to improve the optimization parameter <NUM>. The optimization controller <NUM>, according to the invention, evaluates a cost function that determines operational states <NUM>-<NUM> to <NUM>-N that maximize the optimization parameter <NUM> based on the given constraint <NUM>. Example constraints <NUM> can include available power (e.g., device battery capacity), the presence or amount of signal clipping (e.g., saturation), power regulations (e.g., a specific-absorption rate (SAR) or a maximum permissible exposure (MPE)), or the presence or amount of interference from other radar circuits <NUM> or other components within the user device <NUM> (e.g., a speaker or a wireless communication transceiver).

The optimization controller <NUM> can also monitor one or more triggers <NUM>, which cause the optimization controller <NUM> to re-evaluate the operational states <NUM>-<NUM> to <NUM>-N of the radar circuits <NUM>-<NUM> to <NUM>-N. A trigger <NUM> can be activated based on information provided by any of the radar circuits <NUM>-<NUM> to <NUM>-N, or based on information provided by other components within the user device <NUM>, such as the sensor <NUM>, the power circuit <NUM>, or the computer processor <NUM>. Example triggers <NUM> can include one of the radar circuits <NUM>-<NUM> to <NUM>-N determining that the user <NUM> is no longer present, determining that the user <NUM> is present but outside a specified range, determining that the user <NUM> is approaching the user device <NUM>, or determining that the user is preparing to perform a gesture or has started performing a gesture. Other example triggers <NUM> can include the sensor <NUM> detecting movement or rotation of the user device <NUM>, the power circuit <NUM> determining that the available power for operating the multi-radar system <NUM> has decreased below a predetermined threshold, the power circuit <NUM> causing the user device <NUM> to operate according to a low-power mode to conserve power, or the computer processor <NUM> activating a different radar-based application <NUM>. An example trigger <NUM> can also include an expiration of a timer.

During operation, the optimization controller <NUM> can reference information that is stored within its computer-readable storage medium to determine the operational variables <NUM>, the optimization parameter <NUM>, and the constraint <NUM>. Additionally or alternatively, the optimization controller <NUM> can accept information from the radar circuits <NUM>-<NUM> to <NUM>-N, the sensor <NUM>, the power circuit <NUM>, or the computer processor <NUM> to determine the operational variables <NUM>, the optimization parameter <NUM>, and/or the constraint <NUM>.

For example, the radar circuits <NUM>-<NUM> to <NUM>-N provide radar data <NUM>-<NUM> to <NUM>-N to the optimization controller <NUM>. The radar data <NUM>-<NUM> to <NUM>-N can include information about whether or not an object (e.g., the user <NUM>) is present, position or motion information about a detected object (e.g., range, azimuth, elevation, range rate, or velocity), a type of gesture performed by a detected user <NUM>, an alert regarding a potential collision, measured vital signs of the user <NUM>, and so forth. In some cases, the radar data <NUM>-<NUM> to <NUM>-N can include raw samples of the radar receive signals <NUM>-<NUM> to <NUM>-M (e.g., samples of the digital beat signals <NUM>-<NUM> to <NUM>-M of <FIG>) or processed data (e.g., range-Doppler maps, range-azimuth-elevation maps). In some cases, the radar data <NUM>-<NUM> to <NUM>-N can additionally include the operational variables <NUM> associated with the respective radar circuits <NUM>-<NUM> to <NUM>-N.

Additionally or alternatively, the optimization controller <NUM> accepts sensor data <NUM> from the sensor <NUM>, power data <NUM> from the power circuit <NUM>, and an application request <NUM> from the computer processor <NUM>. The sensor data <NUM> can include information such as an orientation of the user device <NUM> (e.g., a portrait orientation or a landscape orientation), whether or not the user device <NUM> is moving, or other environmental conditions. The power data <NUM> can include information about an amount of available power for operating the multi-radar system <NUM>, remaining power stored by a battery of the power circuit <NUM>, a power mode of the user device <NUM> (e.g., a low-power mode or a normal power mode), or whether or not the user device <NUM> is being powered by an external power source. The application request <NUM> can include radar performance parameters associated with a radar-based application <NUM> executed by the computer processor <NUM>. These parameters can include the types of gestures that can be used to interact with the radar-based application <NUM>, a level of accuracy or responsiveness requested by the radar-based application <NUM>, or combinations thereof.

The optimization controller <NUM> monitors the radar data <NUM>-<NUM> to <NUM>-N, the sensor data <NUM>, the power data <NUM>, and the application request <NUM> to detect a trigger event. The trigger event occurs if the operating environment changes. By monitoring this information, the optimization controller <NUM> can detect a change in the operating environment (e.g., detect the trigger <NUM>). Responsive to detecting this change, the optimization controller <NUM> analyzes the operational variables <NUM>, the one or more optimization parameters <NUM>, and the one or more constraints <NUM> to determine individual operational states <NUM> of the radar circuits <NUM>-<NUM> to <NUM>-N. The optimization controller <NUM> provides the operational states <NUM>-<NUM> to <NUM>-N to the radar circuits <NUM>-<NUM> to <NUM>-N. The process of determining the operational states <NUM>-<NUM> to <NUM>-N based on the operational variables <NUM>, the optimization parameter <NUM>, and the constraint <NUM> is further described with respect to <FIG>.

<FIG> illustrates an example scheme implemented by the optimization controller <NUM> for optimizing operation of the multi-radar system <NUM>. In the depicted configuration, the optimization controller <NUM> implements transceiver-based optimization modules <NUM>-<NUM> to <NUM>-N, processing-based optimization modules <NUM>-<NUM> to <NUM>-Q, and a joint optimization module <NUM>. The quantity of processing-based optimization modules <NUM> (Q) can be similar to or different than the quantity of transceiver-based optimization modules <NUM> (N).

The transceiver-based optimization modules <NUM>-<NUM> to <NUM>-N are associated with respective radar circuits <NUM>-<NUM> to <NUM>-N. Each transceiver-based optimization module <NUM> selects a candidate transceiver configuration <NUM> for its corresponding radar circuit <NUM> based on the operational variables <NUM> associated with the radar circuit <NUM>, one or more optimization parameters <NUM>, and one or more constraints <NUM>. For example, the transceiver-based optimization module <NUM>-<NUM> executes a cost function to determine a candidate transceiver configuration <NUM>-<NUM> that maximizes signal-to-noise ratio performance for the corresponding radar circuit <NUM>-<NUM> given the amount of available power. The candidate transceiver configurations <NUM>-<NUM> to <NUM>-N are provided to the processing-based optimization modules <NUM>-<NUM> to <NUM>-Q and the joint optimization module <NUM>.

The processing-based optimization modules <NUM>-<NUM> to <NUM>-Q are associated with different sets of the radar circuits <NUM>-<NUM> to <NUM>-N. Each processing-based optimization module <NUM> considers a set of the radar circuits <NUM>-<NUM> to <NUM>-N to determine candidate processing configurations <NUM> for each radar circuit <NUM> within the set. For example, the processing-based optimization modules <NUM>-<NUM> can consider the information requested by an active radar-based application <NUM> to determine the processing configuration <NUM> that maximizes the F-score given the candidate transceiver configurations <NUM>-<NUM> and <NUM>-<NUM> of radar circuits <NUM>-<NUM> and <NUM>-<NUM>. The processing-based optimization modules <NUM>-<NUM> to <NUM>-Q provide sets of the candidate processing configurations <NUM>-<NUM> to <NUM>-Q to the joint optimization module <NUM>.

The joint optimization module <NUM> analyzes the candidate transceiver configurations <NUM>-<NUM> to <NUM>-N and the sets of candidate processing configurations <NUM>-<NUM> to <NUM>-Q to determine the operational states <NUM>-<NUM> to <NUM>-N. Optionally, the joint optimization module <NUM> can cause the transceiver-based optimization modules <NUM>-<NUM> to <NUM>-N and the processing-based optimization modules <NUM>-<NUM> to <NUM>-Q to repeat the above process to further optimize the operational states <NUM>-<NUM> to <NUM>-N with a different set of operational variables <NUM>, optimization parameters <NUM>, or constraints <NUM>. A variety of different situations can cause the optimization controller <NUM> to adjust the operational states <NUM>-<NUM> to <NUM>-N of the radar circuits <NUM>-<NUM> to <NUM>-N, examples of which are further described with respect to <FIG>.

<FIG> illustrates an example situation in which the optimization controller <NUM> optimizes operation of the multi-radar system <NUM> based a detected change associated with the user <NUM>. In this scenario, the user device <NUM> includes the radar circuits <NUM>-<NUM> and <NUM>-<NUM>. At <NUM>, the optimization controller <NUM> initializes the operational states <NUM>-<NUM> and <NUM>-<NUM> of the radar circuits <NUM>-<NUM> and <NUM>-<NUM> to minimize power consumption of the multi-radar system <NUM>. In particular, the optimization controller <NUM> causes the radar circuit <NUM>-<NUM> to operate according to the off state <NUM> (of <FIG>) and causes the radar circuit <NUM>-<NUM> to operate according to the pre-gesture-detection state <NUM> (of <FIG>). In the off state <NUM>, the radar circuit <NUM>-<NUM> is powered down and does not transmit or receive radar signals. In the pre-gesture-detection state <NUM>, the radar circuit <NUM>-<NUM> transmits and receives radar signals while conserving power. For example, the radar circuit <NUM>-<NUM> can operate with a frame rate of <NUM> for the burst-mode feature frames <NUM> and with an ADC sampling rate <NUM> of one mega-sample per second (Msps). This enables the radar circuit <NUM>-<NUM> to detect an intension of the user <NUM> to perform a gesture (e.g., detect the user <NUM> positioning themselves to perform a gesture or detect the start of the gesture).

At <NUM>, the user <NUM> performs a gesture, which is detected by the radar circuit <NUM>-<NUM> and communicated to the optimization controller <NUM>. This triggers the optimization controller <NUM> to adjust the operational states <NUM>-<NUM> and <NUM>-<NUM> of the radar circuits <NUM>-<NUM> and <NUM>-<NUM>. At <NUM>, the optimization controller <NUM> causes both the radar circuits <NUM>-<NUM> and <NUM>-<NUM> to operate according to the gesture-recognition state <NUM>. The gesture-recognition state <NUM> enables the radar circuits <NUM>-<NUM> to <NUM>-<NUM> to jointly detect the gesture performed by the user <NUM>. In comparison to the pre-gesture-detection state <NUM>, the gesture-recognition state <NUM> can decrease the frame rate to <NUM>.

<FIG> illustrates an example situation in which the optimization controller <NUM> optimizes operation of the multi-radar system <NUM> based on detected change in an orientation of the user device <NUM>. In this scenario, the user device <NUM> includes the radar circuits <NUM>-<NUM> and <NUM>-<NUM>. At <NUM>, the optimization controller <NUM> initializes the operational states <NUM>-<NUM> and <NUM>-<NUM> of the radar circuits <NUM>-<NUM> and <NUM>-<NUM> based on a portrait orientation of the user device <NUM>. In this case, the optimization controller <NUM> determines operational states <NUM>-<NUM> and <NUM>-<NUM> that improve the signal-to-noise ratio performance while limiting power consumption.

Consider a situation in which the radar circuit <NUM>-<NUM> realizes a lower signal-to-noise ratio than the radar circuit <NUM>-<NUM> for detecting gestures near a bottom portion of the user device <NUM>. This can be due to the orientation of the radar circuit <NUM>-<NUM> antenna <NUM> and the antenna pattern of the radar circuit <NUM>-<NUM>. The optimization controller <NUM> improves, at <NUM>, the signal-to-noise ratio performance of the radar circuit <NUM>-<NUM> by causing the radar circuit <NUM>-<NUM> to operate according to the high-power state <NUM> (e.g., full-power state). To compensate for the increase in power consumption caused by operating the radar circuit <NUM>-<NUM> in the high-power state <NUM>, the optimization controller <NUM> causes the radar circuit <NUM>-<NUM> to operate according to the low-power state <NUM>. In the high-power state <NUM>, the radar circuit <NUM>-<NUM> has a higher transmit power <NUM> than the radar circuit <NUM>-<NUM> in the low-power state <NUM>. Additionally, the radar circuit <NUM>-<NUM> operates with a larger quantity of chirps <NUM> per a burst-mode feature frame <NUM>, a higher frame rate <NUM> of burst-mode feature frames <NUM>, and a higher ADC higher sampling rate <NUM> relative to the radar circuit <NUM>-<NUM>. This causes the radar circuit <NUM>-<NUM> to consume more power than the radar circuit <NUM>-<NUM>.

At <NUM>, the user <NUM> changes the orientation of the user device <NUM> to a landscape orientation. The optimization controller <NUM> adjusts the operational states <NUM>-<NUM> and <NUM>-<NUM> of the radar circuits <NUM>-<NUM> and <NUM>-<NUM> based on the landscape orientation. In this example, the optimization controller <NUM> causes the radar circuit <NUM>-<NUM> to operate according to the low-power state <NUM> and causes the radar circuit <NUM>-<NUM> to operate according to the high-power state <NUM>. Optionally, the optimization controller <NUM> can cause the radar circuit <NUM>-<NUM> or the radar circuit <NUM>-<NUM> to operate in the off state <NUM> if the sensor <NUM> or either radar circuit <NUM>-<NUM> or <NUM>-<NUM> determines that the user <NUM>'s hand is obstructing the radar circuit <NUM>-<NUM> or <NUM>-<NUM>.

In an alternative scenario, the optimization controller <NUM> can determine operational states <NUM>-<NUM> and <NUM>-<NUM> of the radar circuits <NUM>-<NUM> and <NUM>-<NUM> to improve angular estimation and limit power consumption. In this case, the radar circuit <NUM>-<NUM> can be better positioned in the portrait mode to capture angular information associated with a swipe gesture performed by the user <NUM>. Therefore, in the portrait mode, the optimization controller <NUM> can improve angular estimation by causing the radar circuit <NUM>-<NUM> to operate at the high-power state <NUM> and the radar circuit <NUM>-<NUM> to operate at the low-power state <NUM> to conserve power. By operating the radar circuit <NUM>-<NUM> in the high-power state, the accuracy of the radar circuit <NUM>-<NUM> for angular estimation can be improved relative to the accuracy in the low-power state <NUM>. In the landscape mode, the radar circuit <NUM>-<NUM> can be better positioned to capture angular information for the swipe gesture. As such, the optimization controller <NUM> can improve angular estimation by causing the radar circuit <NUM>-<NUM> to operate at the high-power state <NUM> and the radar circuit <NUM>-<NUM> to operate at the low-power state <NUM> to conserve power.

<FIG> illustrates an example situation in which the optimization controller <NUM> optimizes operation of the multi-radar system <NUM> based on a detected presence of the user <NUM>. At <NUM>, the user <NUM> is outside a detectable range of the multi-radar system <NUM>. The optimization controller <NUM> determines the operational states <NUM>-<NUM> and <NUM>-<NUM> of the radar circuits <NUM>-<NUM> and <NUM>-<NUM> to minimize power consumption of the multi-radar system <NUM>. Considering that the radar circuit <NUM>-<NUM> has sufficient signal-to-noise ratio performance for detecting the user <NUM> approaching the user device <NUM> from one or more directions, the optimization controller <NUM> causes the radar circuit <NUM>-<NUM> to transition to the off state <NUM> to conserve power. The optimization controller <NUM> also causes the radar circuit <NUM>-<NUM> to operate in the presence-detection state <NUM>, which enables the radar circuit <NUM>-<NUM> to detect the user <NUM> once the user <NUM> is within the detectable range associated with the radar circuit <NUM>-<NUM>.

At <NUM>, the radar circuit <NUM>-<NUM> detects the user <NUM>. In response, the optimization controller <NUM> causes the radar circuits <NUM>-<NUM> and <NUM>-<NUM> to operate according to the gesture-recognition state <NUM> to enable the radar circuits <NUM>-<NUM> and <NUM>-<NUM> to detect a gesture performed by the user <NUM>, such as a reach gesture. In comparison, the gesture-recognition state <NUM> can increase the quantity of chirps <NUM> per burst-mode feature frame <NUM> within the radar framing structure <NUM> compared to the presence-detection state <NUM>.

<FIG> illustrates an example situation in which the optimization controller <NUM> optimizes operation of the multi-radar system <NUM> based on a detected presence of multiple users <NUM>. At <NUM>, user <NUM>-<NUM> interacts with the user device <NUM>. The optimization controller <NUM> causes the radar circuit <NUM>-<NUM> to operate according to the off state <NUM> to conserve power and causes the radar circuit <NUM>-<NUM> to operate according to the presence-detection state <NUM> to enable detection of additional users.

At <NUM>, the radar circuit <NUM>-<NUM> detects the presence of another user <NUM>-<NUM>. The optimization controller <NUM> causes the radar circuit <NUM>-<NUM> to operate according to the presence-detection state <NUM> and causes the radar circuit <NUM>-<NUM> to operate according to the gesture-recognition state <NUM>. In this manner, the radar circuit <NUM>-<NUM> can detect when either of the users <NUM>-<NUM> to <NUM>-<NUM> leave a detectable range of the multi-radar system <NUM> and the radar circuit <NUM>-<NUM> can detect gestures performed by the users <NUM>-<NUM> and <NUM>-<NUM>. To conserve power, the gesture-recognition state <NUM> can have a slower ADC sampling rate <NUM> relative to the presence-detection state <NUM>. In this example, different radar circuits <NUM> are configured to enable different types of analysis, such as presence detection and gesture recognition. In an alternative implementation, either or both radar circuits <NUM>-<NUM> and <NUM>-<NUM> can operate in another operational state <NUM> that supports both presence detection and gesture recognition.

<FIG> depicts an example method <NUM> performed by a multi-radar system. Method <NUM> is shown as sets of operations (or acts) performed but not necessarily limited to the order or combinations in which the operations are shown herein. Further, any of one or more of the operations may be repeated, combined, reorganized, or linked to provide a wide array of additional and/or alternate methods. In portions of the following discussion, reference may be made to the environment <NUM>-<NUM> to <NUM>-<NUM> of <FIG>, and entities detailed in <FIG>, <FIG>, <FIG> or <FIG>, reference to which is made for example only. The techniques are not limited to performance by one entity or multiple entities operating on one device.

At <NUM>, a first radar circuit of a multi-radar system's two or more radar circuits is in (e.g., operates according to) a first operational state. For example, the radar circuit <NUM>-<NUM> of the multi-radar system <NUM> operates according to a first operational state <NUM>-<NUM>. The first operational state <NUM>-<NUM> can be the off state <NUM> (as shown in <FIG>, <FIG>, or <FIG> at <NUM>, <NUM>, and <NUM>, respectively), the low-power state <NUM>, the high-power state <NUM> (as shown in <FIG> at <NUM>), the pre-gesture-detection state <NUM>, the gesture-recognition state <NUM>, or the presence-detection state <NUM> (as shown in <FIG> at <NUM>). In particular, the first operational state <NUM>-<NUM> specifies a particular transceiver configuration <NUM> and a particular processing configuration <NUM> for the radar circuit <NUM>-<NUM>.

At <NUM>, a second radar circuit of the multi-radar system operates is in (e.g., operates according to) a second operational state. For example, the radar circuit <NUM>-<NUM> of the multi-radar system <NUM> operates according to a second operational state <NUM>-<NUM>. The second operational state <NUM>-<NUM> can be the off state <NUM>, the low-power state <NUM> (as shown in <FIG> at <NUM>), the high-power state <NUM>, the pre-gesture-detection state <NUM> (as shown in <FIG> at <NUM>), the gesture-recognition state <NUM>, or the presence-detection state <NUM> (as shown in <FIG> at <NUM> and <FIG> at <NUM>). In particular, the second operational state <NUM>-<NUM> specifies a particular transceiver configuration <NUM> and a particular processing configuration <NUM> for the radar circuit <NUM>-<NUM>. The second operational state <NUM>-<NUM> of the second radar circuit <NUM>-<NUM> can be similar to or different from the first operational state <NUM>-<NUM> of the first radar circuit <NUM>-<NUM>.

At <NUM>, a trigger event is detected. The trigger event represents a change in an operating environment of the multi-radar system. For example, the optimization controller <NUM> detects a trigger event associated with a change in the multi-radar system <NUM>'s operating environment. Example trigger events include a detected change in a position of the user <NUM>, a detected change in the quantity of users <NUM> present, a detected change in an orientation of the user device <NUM>, or a detected change in the amount of power available within the user device <NUM>. Other example trigger events are further described with respect to <FIG>.

At <NUM>, operation of at least one of the first radar circuit or the second radar circuit is selectively altered responsive to detection of the trigger event. For example, the optimization controller <NUM> selectively alters operation of the radar circuit <NUM>-<NUM> or the radar circuit <NUM>-<NUM> responsive to (or based on) detection of the trigger event. The adjusting or altering of the operation may include one of causing (or directing) the first radar circuit to operate according to a third operational state that is different than the first operational state or causing (or directing) the second radar circuit to operate according to a fourth operational state that is different than the second operational state. Alternatively or additionally, adjusting or altering a respective operation state <NUM> of a radar circuit <NUM> may include transitioning or configuring the radar circuit <NUM> to operate in an operational state <NUM> that is different from a current operational state of the radar circuit <NUM>. Examples third operational states and the fourth operational states are described in <FIG> at <NUM>, <FIG> at <NUM>, <FIG> at <NUM>, and <FIG> at <NUM>.

The optimization controller <NUM> can adjust the operational states <NUM>-<NUM> and <NUM>-<NUM> based on changes to an optimization parameter <NUM> or a constraint <NUM>, which are used to determine the operational states <NUM>-<NUM> and <NUM>-<NUM>. In this way, the optimization controller <NUM> can optimize performance of the multi-radar system <NUM> in the context of the given constraints <NUM>, such as available power.

<FIG> illustrates various components of an example computing system <NUM> that can be implemented as any type of client, server, and/or computing device as described with reference to the previous <FIG> to optimize operation of a multi-radar system <NUM>.

The computing system <NUM> includes communication devices <NUM> that enable wired and/or wireless communication of device data <NUM> (e.g., received data, data that is being received, data scheduled for broadcast, or data packets of the data). The computing system <NUM> also includes one or more multi-radar systems <NUM>. The device data <NUM> or other device content can include configuration settings of the device, media content stored on the device, and/or information associated with a user <NUM> of the device. Media content stored on the computing system <NUM> can include any type of audio, video, and/or image data. The computing system <NUM> includes one or more data inputs <NUM> via which any type of data, media content, and/or inputs can be received, such as human utterances, the radar-based application <NUM>, user-selectable inputs (explicit or implicit), messages, music, television media content, recorded video content, and any other type of audio, video, and/or image data received from any content and/or data source.

The computing system <NUM> also includes communication interfaces <NUM>, which can be implemented as any one or more of a serial and/or parallel interface, a wireless interface, any type of network interface, a modem, and as any other type of communication interface. The communication interfaces <NUM> provide a connection and/or communication links between the computing system <NUM> and a communication network by which other electronic, computing, and communication devices communicate data with the computing system <NUM>.

The computing system <NUM> includes one or more processors <NUM> (e.g., any of microprocessors, controllers, and the like), which process various computer-executable instructions to control the operation of the computing system <NUM> and to enable techniques for, or in which can be embodied, gesture recognition in the presence of saturation. Alternatively or additionally, the computing system <NUM> can be implemented with any one or combination of hardware, firmware, or fixed logic circuitry that is implemented in connection with processing and control circuits which are generally identified at <NUM>. Although not shown, the computing system <NUM> can include a system bus or data transfer system that couples the various components within the device. A system bus can include any one or combination of different bus structures, such as a memory bus or memory controller, a peripheral bus, a universal serial bus, and/or a processor or local bus that utilizes any of a variety of bus architectures.

The computing system <NUM> also includes a computer-readable media <NUM>, such as one or more memory devices that enable persistent and/or non-transitory data storage (i.e., in contrast to mere signal transmission), examples of which include random access memory (RAM), non-volatile memory (e.g., any one or more of a read-only memory (ROM), flash memory, EPROM, EEPROM, etc.), and a disk storage device. The disk storage device may be implemented as any type of magnetic or optical storage device, such as a hard disk drive, a recordable and/or rewriteable compact disc (CD), any type of a digital versatile disc (DVD), and the like. The computing system <NUM> can also include a mass storage media device (storage media) <NUM>.

The computer-readable media <NUM> provides data storage mechanisms to store the device data <NUM>, as well as various device applications <NUM> and any other types of information and/or data related to operational aspects of the computing system <NUM>. For example, an operating system <NUM> can be maintained as a computer application with the computer-readable media <NUM> and executed on the processors <NUM>. The device applications <NUM> may include a device manager, such as any form of a control application, software application, signal-processing and control module, code that is native to a particular device, a hardware abstraction layer for a particular device, and so on.

The device applications <NUM> also include any system components, engines, or managers to optimize operation of the multi-radar system <NUM>. In this example, the device applications <NUM> includes the radar-based application <NUM> and the optimization controller <NUM> of <FIG>.

Claim 1:
A method performed by a multi-radar system (<NUM>) implemented within a device, the multi-radar system (<NUM>) comprising two or more radar circuits (<NUM>-<NUM> - <NUM>-N) at different positions on the device, each radar circuit comprising at least one antenna and at least one transceiver coupled to the at least one antenna to transmit and/or receive radar signals,
the method comprising:
causing a first radar circuit (<NUM>-<NUM>) of the two or more radar circuits (<NUM>-<NUM> - <NUM>-N) to be in a first operational state;
causing a second radar circuit (<NUM>-<NUM>) of the two or more radar circuits (<NUM>-<NUM> - <NUM>-N) to be in a second operational state;
detecting a trigger event that represents a change in an operating environment of the multi-radar system;
responsive to detecting the trigger event, selectively altering operation of at least one of the first radar circuit (<NUM>-<NUM>) or the second radar circuit (<NUM>-<NUM>), the selective altering comprising at least one of:
causing the first radar circuit (<NUM>-<NUM>) to be in a third operational state that is different than the first operational state; or
causing the second radar circuit (<NUM>-<NUM>) to be in a fourth operational state that is
different than the second operational state;
characterised in that the method further comprises:
determining operational variables associated with the two or more radar circuits (<NUM>-<NUM> - <NUM>-N);
determining at least one optimization parameter associated with the multi-radar system (<NUM>);
determining at least one constraint associated with the multi-radar system; and determining the third operational state and the fourth operational state based on the operational variables, the at least one optimization parameter and the at least one constraint by
executing a cost function to determine the third operational state and the fourth operational state that maximizes the at least one optimization parameter in context of the at least one constraint.