Patent ID: 12241963

DETAILED DESCRIPTION

FIGS.1through13, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably-arranged system or device.

To meet the demand for wireless data traffic having increased since deployment of the fourth generation (4G) communication systems, efforts have been made to develop and deploy an improved 5th generation (5G) or pre-5G or new radio (NR) communication system. Therefore, the 5G or pre-5G communication system is also called a “beyond 4G network” or a “post long term evolution (LTE) system.”

The 5G communication system is considered to be implemented in higher frequency (such as millimeter wave (mmWave)) bands, e.g., 28 GHz or 60 GHz bands, so as to accomplish higher data rates or in lower frequency bands, such as 6 GHz, to enable robust coverage and mobility support. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.

In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation and the like.

An electronic device, according to embodiments of the present disclosure can include a user equipment (UE) such as a 5G terminal. The electronic device can also refer to any component such as mobile station, subscriber station, remote terminal, wireless terminal, receive point, vehicle, or user device. The electronic device could be a mobile telephone, a smartphone, a monitoring device, an alarm device, a fleet management device, an asset tracking device, an automobile, a desktop computer, an entertainment device, an infotainment device, a vending machine, an electricity meter, a water meter, a gas meter, a security device, a sensor device, an appliance, and the like. Additionally, the electronic device can include a personal computer (such as a laptop, a desktop), a workstation, a server, a television, an appliance, and the like. In certain embodiments, an electronic device can be a portable electronic device such as a portable communication device (such as a smartphone or mobile phone), a laptop, a tablet, an electronic book reader (such as an e-reader), a personal digital assistants (PDAs), a portable multimedia player (PMP), an MP3 player, a mobile medical device, a virtual reality headset, a portable game console, a camera, and a wearable device, among others. Additionally, the electronic device can be at least one of a part of a piece of furniture or building/structure, an electronic board, an electronic signature receiving device, a projector, or a measurement device. The electronic device is one or a combination of the above-listed devices. Additionally, the electronic device as disclosed herein is not limited to the above-listed devices and can include new electronic devices depending on the development of technology. It is noted that as used herein, the term “user” may denote a human or another device (such as an artificial intelligent electronic device) using the electronic device.

Beamforming is an important factor when an electronic device (such as a UE) tries to establish a connection with a base station (BS). To compensate for the narrower analog beamwidth in mmWave, analog beams sweeping can be employed to enable wider signal reception or transmission coverage for the UE. A beam codebook comprises a set of codewords, where a codeword is a set of analog phase shift values, or a set of amplitude plus phase shift values, applied to the antenna elements, in order to form an analog beam.FIG.4A, described below, illustrates a UE equipped with two mmWave antenna modules or panels located on the left and the right edges of the UE. A beam management procedure is implemented at the UE to maintain the best antenna module as well as the corresponding best beam of the antenna module for signal reception and transmission by the UE. The UE may also use multiple antenna modules simultaneously, in which case the beam management procedure can determine the best beam of each antenna module for signal reception and transmission by the UE.

Embodiments of the present disclosure take into consideration that beamforming is a used for reliable mmWave communications but at the same time beamforming also can cause a concern for radio frequency exposure on human body, beyond various governmental regulations. Beamforming is typically used at both the infrastructure or network side (such as at the base station or the access point) and the UE side. The process of beamforming is to adjust the antenna weights such that the transmission energy is concentrated in some direction. This focus of energy can help provide strong link signal for communications, but at the same time this means more radiation power in that direction and could raise concern on the exposure to body of the user. Due to such health concern, regulatory bodies (such as the Federal Communications Commission (FCC) in the United States of America) have sets of regulations and guidance governing such exposure. Exposure includes both exposure at low frequency (<6 GHz) and exposure at high frequency (>6 GHz). Power density (PD) is used as the exposure metric at high frequency.

Exposure limit poses a challenge regarding 5G millimeter wave uplink (UL). As discussed above, narrow beams (formed by beamforming techniques) are used for 5G millimeter wave operation, however, beamforming increases the PD and, consequently, the exposure. Certain mmWave communications take a very conservative measure to meet the exposure regulations. For example, one such approach is to use low enough Equivalent Isotropically Radiated Power (EIRP) by adjusting the duty cycle and either (i) lowering the transmit (TX) power, (ii) lowering the antenna gain, or (iii) both lower the TX power and the antenna gain.

Embodiments of the present disclosure take into consideration that while such a conservative measure can ensure regulatory compliance, it forces the communication module to operate at suboptimal link quality and thus the electronic device cannot reap the potential for very high data rate services. For example, some solutions (non-sensing solutions) assume worst case exposure. Embodiments of the present disclosure take into consideration that to guard against exceeding the limit, using low power, using wide beams, or a combination thereof. Using low power or wide beams can limit UL quality in both coverage and throughput.

Accordingly, embodiments of the present disclosure relate to using radar to assess a situation by sensing the surroundings of the electronic device. By assessing the situation, the electronic device can avoid a pessimistic TX power control. For example, a smart exposure control solution can keep exposure compliance while minimizing the opportunity loss for communication beamforming operations. Embodiments of the present disclosure describe using radar to both detect a body part and determine a direction that the body part is present. Upon detecting a body part and determining its location, the electronic device can manage the beams for communication to maintain regulatory RF exposure compliance while operating at enhanced link quality.

Radar sensing can be used for ranging, angle or both. For example, when radar is used for ranging only, the electronic device can determine whether a human body part is present and adjust the TX power. For another example, when radar is used for ranging and angle, the electronic device can determine whether a human body part is present and its approximate location and adjust the TX power, for beamforming, based on the location of the human body part. For instance, the electronic device can reduce the TX power at or near the location of the human body part and increase the TX power at locations where the human body part is absent. For yet another example, when radar is used for ranging and angle, the electronic device can determine whether a human body part is present and its approximate location and select one or more beams for beamforming based on the location of the human body part. In this example, the angle information can be used to identify if the body part is within the main beam direction of certain beams.

Embodiments of the present disclosure take into consideration that the regulatory bodies limit exposure due to such health concern with respect to a human body and not inanimate objects. Accordingly, embodiments of the present disclosure relate to using radar to distinguish between a human body part and an inanimate object, such as a table. One way to distinguish body part from other objects (such as inanimate objects) is to rely on movement. For example, there are always some micro-movement of the live body (such as breathing cycles or some other involuntary muscle activities). While micro-movements are a good identifier of a human body, it can be quite challenging to reliably detect these minor movements in a static setting as it may require a very long radar frame duration.

Embodiments of the present disclosure take into consideration that while longer processing frames are able to identify small movements of the human body, it can introduce ambiguity in angle estimation when the body part has a large motion. For example, if the object moves over a certain amount the electronic device may be unable to determine the angle that the object is relative to the electric device due to a smearing effect. Accordingly, embodiments of the present disclosure relate to determining whether to use a single radar frame or multiple radar frames for detecting movement, performing angle estimation, and determining whether the object is a human body part or an inanimate object.

Embodiments of the present disclosure also relate to methods for indirectly assessing the speed of an object (also referred to as a target) to select a duration to derive a spatial covariance matrix. For example, using long radar frames can improve the quality of the spatial covariance matrix in terms of signal to noise ratio if the target stays relatively static during the radar frame. It is noted that indirectly assessing the speed of an object is used since certain embodiments of the present disclosure use non-uniform radar pulse spacing and the speed of the object may not be directly estimated. Additionally, embodiments of the present disclosure describe performing angle estimation when using multiple-frame radar detection with non-uniform pulse spacing. For example, when the object is moving fast, embodiments of the present disclosure describe using a short frame duration. For another example, when the object is moving slow or remaining stationary (except for micro-movements), embodiments of the present disclosure describe using a longer frame (or multiple frames) for the spatial covariance matrix.

While the descriptions of the embodiments of the present discloser, describe a radar based system for object detection and motion detection, the embodiments can be applied to any other radar based and non-radar based recognition systems. That is, the embodiments of the present disclosure are not restricted to radar and can be applied to other types of sensors (such as an ultrasonic sensor) that can provide both range, angle, speed measurements, or any combination thereof. It is noted that when applying the embodiments of the present disclosure using a different type of sensor (a sensor other than a radar transceiver), various components may need to be tuned accordingly.

FIG.1illustrates an example communication system100in accordance with an embodiment of this disclosure. The embodiment of the communication system100shown inFIG.1is for illustration only. Other embodiments of the communication system100can be used without departing from the scope of this disclosure.

The communication system100includes a network102that facilitates communication between various components in the communication system100. For example, the network102can communicate IP packets, frame relay frames, Asynchronous Transfer Mode (ATM) cells, or other information between network addresses. The network102includes one or more local area networks (LANs), metropolitan area networks (MANs), wide area networks (WANs), all or a portion of a global network such as the Internet, or any other communication system or systems at one or more locations.

In this example, the network102facilitates communications between a server104and various client devices106-114. The client devices106-114may be, for example, a smartphone (such as a UE), a tablet computer, a laptop, a personal computer, a wearable device, a head mounted display, or the like. The server104can represent one or more servers. Each server104includes any suitable computing or processing device that can provide computing services for one or more client devices, such as the client devices106-114. Each server104could, for example, include one or more processing devices, one or more memories storing instructions and data, and one or more network interfaces facilitating communication over the network102.

Each of the client devices106-114represent any suitable computing or processing device that interacts with at least one server (such as the server104) or other computing device(s) over the network102. The client devices106-114include a desktop computer106, a mobile telephone or mobile device108(such as a smartphone), a PDA110, a laptop computer112, and a tablet computer114. However, any other or additional client devices could be used in the communication system100, such as wearable devices. Smartphones represent a class of mobile devices108that are handheld devices with mobile operating systems and integrated mobile broadband cellular network connections for voice, short message service (SMS), and Internet data communications. In certain embodiments, any of the client devices106-114can emit and collect radar signals via a measuring (or radar) transceiver.

In this example, some client devices108-114communicate indirectly with the network102. For example, the mobile device108and PDA110communicate via one or more base stations116, such as cellular base stations or eNodeBs (eNBs). Also, the laptop computer112and the tablet computer114communicate via one or more wireless access points118, such as IEEE 802.11 wireless access points. Note that these are for illustration only and that each of the client devices106-114could communicate directly with the network102or indirectly with the network102via any suitable intermediate device(s) or network(s). In certain embodiments, any of the client devices106-114transmit information securely and efficiently to another device, such as, for example, the server104.

AlthoughFIG.1illustrates one example of a communication system100, various changes can be made toFIG.1. For example, the communication system100could include any number of each component in any suitable arrangement. In general, computing and communication systems come in a wide variety of configurations, andFIG.1does not limit the scope of this disclosure to any particular configuration. WhileFIG.1illustrates one operational environment in which various features disclosed in this patent document can be used, these features could be used in any other suitable system.

FIG.2illustrates an example electronic device in accordance with an embodiment of this disclosure. In particular,FIG.2illustrates an example electronic device200, and the electronic device200could represent the server104or one or more of the client devices106-114inFIG.1. The electronic device200can be a mobile communication device, such as, for example, a UE, a mobile station, a subscriber station, a wireless terminal, a desktop computer (similar to the desktop computer106ofFIG.1), a portable electronic device (similar to the mobile device108, the PDA110, the laptop computer112, or the tablet computer114ofFIG.1), a robot, and the like.

As shown inFIG.2, the electronic device200includes transceiver(s)210, transmit (TX) processing circuitry215, a microphone220, and receive (RX) processing circuitry225. The transceiver(s)210can include, for example, a RF transceiver, a BLUETOOTH transceiver, a WiFi transceiver, a ZIGBEE transceiver, an infrared transceiver, and various other wireless communication signals. The electronic device200also includes a speaker230, a processor240, an input/output (I/O) interface (IF)245, an input250, a display255, a memory260, and a sensor265. The memory260includes an operating system (OS)261, and one or more applications262.

The transceiver(s)210can include an antenna array including numerous antennas. For example, the transceiver(s)210can be equipped with multiple antenna elements. There can also be one or more antenna modules fitted on the terminal where each module can have one or more antenna elements. The antennas of the antenna array can include a radiating element composed of a conductive material or a conductive pattern formed in or on a substrate. The transceiver(s)210transmit and receive a signal or power to or from the electronic device200. The transceiver(s)210receives an incoming signal transmitted from an access point (such as a base station, WiFi router, or BLUETOOTH device) or other device of the network102(such as a WiFi, BLUETOOTH, cellular, 5G, LTE, LTE-A, WiMAX, or any other type of wireless network). The transceiver(s)210down-converts the incoming RF signal to generate an intermediate frequency or baseband signal. The intermediate frequency or baseband signal is sent to the RX processing circuitry225that generates a processed baseband signal by filtering, decoding, and/or digitizing the baseband or intermediate frequency signal. The RX processing circuitry225transmits the processed baseband signal to the speaker230(such as for voice data) or to the processor240for further processing (such as for web browsing data).

The TX processing circuitry215receives analog or digital voice data from the microphone220or other outgoing baseband data from the processor240. The outgoing baseband data can include web data, e-mail, or interactive video game data. The TX processing circuitry215encodes, multiplexes, and/or digitizes the outgoing baseband data to generate a processed baseband or intermediate frequency signal. The transceiver(s)210receives the outgoing processed baseband or intermediate frequency signal from the TX processing circuitry215and up-converts the baseband or intermediate frequency signal to a signal that is transmitted.

The processor240can include one or more processors or other processing devices. The processor240can execute instructions that are stored in the memory260, such as the OS261in order to control the overall operation of the electronic device200. For example, the processor240could control the reception of forward channel signals and the transmission of reverse channel signals by the transceiver(s)210, the RX processing circuitry225, and the TX processing circuitry215in accordance with well-known principles. The processor240can include any suitable number(s) and type(s) of processors or other devices in any suitable arrangement. For example, in certain embodiments, the processor240includes at least one microprocessor or microcontroller. Example types of processor240include microprocessors, microcontrollers, digital signal processors, field programmable gate arrays, application specific integrated circuits, and discrete circuitry. In certain embodiments, the processor240can include a neural network.

The processor240is also capable of executing other processes and programs resident in the memory260, such as operations that receive and store data. The processor240can move data into or out of the memory260as required by an executing process. In certain embodiments, the processor240is configured to execute the one or more applications262based on the OS261or in response to signals received from external source(s) or an operator. Example, applications262can include a multimedia player (such as a music player or a video player), a phone calling application, a virtual personal assistant, and the like.

The processor240is also coupled to the I/O interface245that provides the electronic device200with the ability to connect to other devices, such as client devices106-114. The I/O interface245is the communication path between these accessories and the processor240.

The processor240is also coupled to the input250and the display255. The operator of the electronic device200can use the input250to enter data or inputs into the electronic device200. The input250can be a keyboard, touchscreen, mouse, track ball, voice input, or other device capable of acting as a user interface to allow a user in interact with the electronic device200. For example, the input250can include voice recognition processing, thereby allowing a user to input a voice command. In another example, the input250can include a touch panel, a (digital) pen sensor, a key, or an ultrasonic input device. The touch panel can recognize, for example, a touch input in at least one scheme, such as a capacitive scheme, a pressure sensitive scheme, an infrared scheme, or an ultrasonic scheme. The input250can be associated with the sensor(s)265, the radar transceiver270, a camera, and the like, which provide additional inputs to the processor240. The input250can also include a control circuit. In the capacitive scheme, the input250can recognize touch or proximity.

The display255can be a liquid crystal display (LCD), light-emitting diode (LED) display, organic LED (OLED), active matrix OLED (AMOLED), or other display capable of rendering text and/or graphics, such as from websites, videos, games, images, and the like. The display255can be a singular display screen or multiple display screens capable of creating a stereoscopic display. In certain embodiments, the display255is a heads-up display (HUD).

The memory260is coupled to the processor240. Part of the memory260could include a RAM, and another part of the memory260could include a Flash memory or other ROM. The memory260can include persistent storage (not shown) that represents any structure(s) capable of storing and facilitating retrieval of information (such as data, program code, and/or other suitable information). The memory260can contain one or more components or devices supporting longer-term storage of data, such as a read only memory, hard drive, Flash memory, or optical disc.

The electronic device200further includes one or more sensors265that can meter a physical quantity or detect an activation state of the electronic device200and convert metered or detected information into an electrical signal. For example, the sensor265can include one or more buttons for touch input, a camera, a gesture sensor, optical sensors, cameras, one or more inertial measurement units (IMUs), such as a gyroscope or gyro sensor, and an accelerometer. The sensor265can also include an air pressure sensor, a magnetic sensor or magnetometer, a grip sensor, a proximity sensor, an ambient light sensor, a bio-physical sensor, a temperature/humidity sensor, an illumination sensor, an Ultraviolet (UV) sensor, an Electromyography (EMG) sensor, an Electroencephalogram (EEG) sensor, an Electrocardiogram (ECG) sensor, an IR sensor, an ultrasound sensor, an iris sensor, a fingerprint sensor, a color sensor (such as a Red Green Blue (RGB) sensor), and the like. The sensor265can further include control circuits for controlling any of the sensors included therein. Any of these sensor(s)265may be located within the electronic device200or within a secondary device operably connected to the electronic device200.

In this embodiment, one of the one or more transceivers in the transceiver210is a radar transceiver270that is configured to transmit and receive signals for detecting and ranging purposes. The radar transceiver270can transmit and receive signals for measuring range and speed of an object that is external to the electronic device200. The radar transceiver270can also transmit and receive signals for measuring the angle a detected object relative to the electronic device200. For example, the radar transceiver270can transmit one or more signals that when reflected off of a moving object and received by the radar transceiver270can be used for determining the range (distance between the object and the electronic device200), the speed of the object, the angle (angle between the object and the electronic device200), or any combination thereof.

The radar transceiver270may be any type of transceiver including, but not limited to a radar transceiver. The radar transceiver270can includes a radar sensor. The radar transceiver270can receive the signals, which were originally transmitted from the radar transceiver270, after the signals have bounced or reflected off of target objects in the surrounding environment of the electronic device200. In certain embodiments, the radar transceiver270is a monostatic radar as the transmitter of the radar signal and the receiver, for the delayed echo, are positioned at the same or similar location. For example, the transmitter and the receiver can use the same antenna or nearly-co-located while using separate, but adjacent antennas. Monostatic radars are assumed coherent, such as when the transmitter and receiver are synchronized via a common time reference.FIG.3A, below, illustrates an example monostatic radar.

AlthoughFIG.2illustrates one example of electronic device200, various changes can be made toFIG.2. For example, various components inFIG.2can be combined, further subdivided, or omitted and additional components can be added according to particular needs. As a particular example, the processor240can be divided into multiple processors, such as one or more central processing units (CPUs), one or more graphics processing units (GPUs), one or more neural networks, and the like. Also, whileFIG.2illustrates the electronic device200configured as a mobile telephone, tablet, or smartphone, the electronic device200can be configured to operate as other types of mobile or stationary devices.

FIG.3Aillustrates an example architecture of a monostatic radar in accordance with an embodiment of this disclosure.FIG.3Billustrates an example frame structure340in accordance with an embodiment of this disclosure.FIG.3Cillustrates an example detailed frame structure350according to embodiments of this disclosure.FIGS.3D and3Eillustrates example pulse structures360and370, respectively, according to embodiments of this disclosure. The embodiments ofFIGS.3A-3Eare for illustration only and other embodiments can be used without departing from the scope of the present disclosure.

FIG.3Aillustrates an electronic device300that includes a processor302, a transmitter304, and a receiver306. The electronic device300can be similar to any of the client devices106-114ofFIG.1, the server104ofFIG.1, or the electronic device200ofFIG.2. The processor302is similar to the processor240ofFIG.2. Additionally, the transmitter304and the receiver306can be included within the radar transceiver270ofFIG.2.

The transmitter304of the electronic device300transmits a signal314to the target object308. The target object308is located a distance310from the electronic device300. For example, the transmitter304transmits a signal314via an antenna. In certain embodiments, the target object308correspond to a human body part. The signal314is reflected off of the target object308and received by the receiver306, via an antenna. The signal314represents one or many signals that can be transmitted from the transmitter304and reflected off of the target object308. The processor302can identify the information associated with the target object308, such as the speed the target object308is moving and the distance the target object308is from the electronic device300, based on the receiver306receiving the multiple reflections of the signals, over a period of time.

Leakage (not shown) represents radar signals that are transmitted from the antenna associated with transmitter304and are directly received by the antenna associated with the receiver306without being reflected off of the target object308.

In order to track the target object308, the processor302analyzes a time difference312from when the signal314is transmitted by the transmitter304and received by the receiver306. It is noted that the time difference312is also referred to as a delay, as it indicates a delay between the transmitter304transmitting the signal314and the receiver306receiving the signal after the signal is reflected or bounced off of the target object308. Based on the time difference312, the processor302derives the distance310between the electronic device300, and the target object308. Additionally, based on multiple time differences312and changes in the distance310, the processor302derives the speed that the target object308is moving.

Monostatic radar is characterized for its delayed echo as the transmitter304of the radar signal and the receiver306of the radar signal essentially are at the same location. In certain embodiments, the transmitter304and the receiver306are co-located either by using a common antenna or nearly co-located but use separate but adjacent antennas. Monostatic radars are assumed coherent such that the transmitter304and the receiver306are synchronized via a common time reference.

A radar pulse is generated as a realization of a desired radar waveform, modulated onto a radio carrier frequency, and transmitted through a power amplifier and antenna, such as a parabolic antenna. In certain embodiments, the pulse radar is omnidirectional. In other embodiments, the pulse radar is focused into a particular direction. When the target object308is within the field of view of the transmitted signal and within a distance310from the radar location, then the target object308will be illuminated by RF power density (W/m2), pt, for the duration of the transmission. Equation (1) describes the first order of the power density, pt.

pt=PT4⁢π⁢R2⁢GT=PT4⁢π⁢R2⁢AT(λ2/4⁢π)=PT⁢ATλ2⁢R2(1)

Referring to Equation (1), PTis the transmit power (W). GTdescribes the transmit antenna gain (dBi) and ATis an effective aperture area (m2). λ corresponds to the wavelength of the radar signal (m), and R corresponds to the distance310between the antenna and the target object308. In certain embodiments, effects of atmospheric attenuation, multi-path propagation, antenna loss and the like are negligible, and therefore not addressed in Equation (1).

The transmit power density impinging onto the target object308surface can cause reflections depending on the material, composition, surface shape and dielectric behavior at the frequency of the radar signal. In certain embodiments, only direct reflections contribute to a detectable receive signal since off-direction scattered signals can be too weak to be received by at the radar receiver. The illuminated areas of the target with normal vectors pointing back at the receiver can act as transmit antenna apertures with directives (gains) in accordance with their effective aperture areas. Equation (2), below, describes the reflective back power.

Pref⁢1=pt⁢At⁢Gt~pt⁢At⁢rt⁢Atλ2/4⁢π=pt⁢RSC(2)

In Equation (2), Pref1describes the effective isotropic target-reflected power (W). The term, At, describes the effective target area normal to the radar direction (m2). The term rtdescribes the reflectivity of the material and shape, which can range from [0, . . . , 1]. The term Gtdescribes the corresponding aperture gain (dBi). RSC is the radar cross section (m2) and is an equivalent area that scales proportional to the actual reflecting area-squared inversely proportional with the wavelength-squared and is reduced by various shape factors and the reflectivity of the material itself. Due to the material and shape dependency, it is difficult to deduce the actual physical area of a target from the reflected power, even if the distance310to the target object308is known.

The target reflected power at the receiver location results from the reflected power density at the reverse distance310collected over the receiver antenna aperture area. Equation (3), below, describes the received target reflected power. It is noted that PRis the received target reflected power (W) and ARis the receiver antenna effective aperture area (m2). In certain embodiments, ARis the same as Ar.

PR=Pref⁢14⁢π⁢R2⁢AR=PT·RSC⁢AT⁢AR4⁢π⁢λ2⁢R4(3)

A radar system can be used as long as the receiver signal exhibits sufficient signal-to-noise ratio (SNR). The value of SNR depends on the waveform and detection method. Equation (4), below, describes the SNR. It is noted that kT is the Boltzmann constant multiplied by the current temperature. B is the radar signal bandwidth (Hz). F is the receiver noise factor which is a degradation of the receive signal SNR due to noise contributions of the receiver circuit itself.

SNR=PRkT·B·F(4)

When the radar signal is a short pulse of duration or width, Tp, the delay or time difference312between the transmission and reception of the corresponding echo is described in Equation (5). τ corresponds to the delay between the transmission and reception of the corresponding echo and equal to Equation (5). c is the speed of light propagation in the air. When there are multiple targets at different distances, individual echoes can be distinguished only if the delays differ by at least one pulse width. As such, the range resolution of the radar is described in Equation (6). A rectangular pulse of a duration TPexhibits a power spectral density as described in Equation (7) and includes a first null at its bandwidth as shown in Equation (8). The range resolution of a radar signal is connected with the bandwidth of the radar waveform is expressed in Equation (9).
τ=2R/c(5)
ΔR=cΔτ/2=cTP/2  (6)
P(f)˜(sin(πfTp)/(πfTp))2(7)
B=1/TP(8)
ΔR=c/2B(9)

Depending on the radar type, various forms of radar signals exist. One example is a Channel Impulse Response (CIR). CIR measures the reflected signals (echoes) from potential targets as a function of distance at the receive antenna module, such as the radar transceiver270ofFIG.2. In certain embodiments, CIR measurements are collected from transmitter and receiver antenna configurations which when combined can produce a multidimensional image of the surrounding environment. The different dimensions can include the azimuth, elevation, range, and Doppler.

The speed resolution (such as the Doppler resolution) of the radar signal is proportional to the radar frame duration. Radar speed resolution is described in Equation (10), below.

Δ⁢v=λ2⁢Ttx-frame(10)
Here, λ is the wavelength of the operating frequency of the radar, and Ttx-frameis the duration of active transmission (simply called the radar frame duration here) of the pulses in the radar frame.

The example frame structure340ofFIG.3Billustrates an example raw radar measurement. The frame structure340describes that time is divided into frames342, where each frame has an active transmission period and a silence period, denoted as frame spacing. During the active transmission period, M pulses344may be transmitted. For example, the example frame structure340includes frame 1, frame 2, frame 3, through frame N. Each frame includes multiple pulses344, such as pulse 1, pulse 2 through pulse M.

In certain embodiments, different transmit and receive antenna configurations activate for each pulse or each frame. In certain embodiments, different transmit or receive antenna configurations activate for each pulse or each frame. It is noted that although the example frame structure340illustrates only one frame type, multiple frame types can be defined in the same frame, where each frame type includes a different antenna configuration. Multiple pulses can be used to boost the SNR of the target or may use different antenna configurations for spatial processing.

In certain embodiments, each pulse or frame may have a different transmit/receive antenna configuration corresponding to the active set of antenna elements and corresponding beamforming weights. For example, each of the M pulses in a frame can have different transmit and receive antenna pair allowing for a spatial scan of the environment (such as using beamforming), and each of the frames342all repeat the same pulses.

The example frame structure340illustrates uniform spacing between pulses and frames. In certain embodiments, any the spacing, even non-uniform spacing, between pulses and frames can be used.

Long radar frames can be used to generate reliable detection of an object even when there is only minor and weak movement, since there is a higher chance that movement will occur during a long frame. To minimize the cost of using long radar frames, embodiments of the present disclosure describe processing multiple radar frames to increase the radar observation time while keeping the same or similar effective radar transmission cycle.

FIG.3Cillustrates a detailed frame structure350according to embodiments of this disclosure. The detailed frame structure350can be similar to the frames342ofFIG.3B. The detailed frame structure350includes frames352a,352b, and352c. Each frame, such as frame352a, has a specific transmission interval354. Similarly, each of the frames are separated by a frame spacing interval, such as the frame spacing interval356and the frame spacing interval356a. For example, frame352aand frame352bare separated by the frame spacing interval356. Similarly, frame352bis separated from the frame352cby frame spacing interval356a. The frame spacing interval356and the frame spacing interval356acan be the same or different time durations.

In certain embodiments, the frame transmission interval354is shorter than the frame spacing interval356. For example, the frame transmission interval354can be 0.2 seconds for each of the frames (such as frame N) and the frame spacing interval356can be 0.8 seconds. In this example, when processing two consecutive frames the effective radar frame increases to 1.2 seconds (the duration of two of the frames which have a transmission interval of 0.2 seconds each, and the frame spacing interval of 0.8 seconds), while the actual radar transmission remains the same. Similarly, when processing three consecutive frames the effective radar frame increases to 2.2 seconds (the duration of three of the frames which have a transmission interval of 0.2 seconds each, and two frame spacings intervals which are 0.8 seconds each), while the actual radar transmission remains the same.

In certain embodiments, one or more radar frames can be used to generate reliable detection of a human body part even when there is only minor and weak movement. As described above RF exposure levels are monitored for human body parts. As such, human body part can be distinguished from an inanimate object (such as a table) based on movements of the object itself. For example, if a single radar-frame does not detect a moving object, embodiments of the present disclosure describe using multiple radar frames to detect the moving object. Upon determining that the object moves, embodiments of the present disclosure describe identifying the angle of arrival of the object relative to the radar transmitter. The radar frames can include non-uniformly spaced radar pulses or uniformly spaced radar pulses.

For instance, if the radar measurements were conducted using multiple frames, where the transmission interval354of a frame is 0.2 second and the frame spacing interval356is 0.8 seconds, the more frames that are processed can increase the ability of the electronic device to identify motion of a detected object. For instance, using one frame to detect motion the detection rate can be 54.5%. When using two frames to detect motion the detection rate can increase to 97.6% and when using three frames to detect motion the detection rate can increase to 100%. As such, the more frames that are used, where each frame is separated by a frame spacing interval356, increases the likelihood that movement is detected, where the movement indicates that a detected object is a human body part instead of an inanimate object. It is noted that if the detected object is an inanimate object, the electronic device may not reduce the transmit power since there is no concern for RF exposure to the inanimate object. In contrast, upon determining that the object moves, then electronic device may reduce the transmit power since there is a concern for RF exposure.

FIGS.3D and3Eillustrates example pulse structures360and370according to embodiments of this disclosure. The pulse structure360ofFIG.3Dhas a number of pulses, such as pulse 1 through pulse 5, which are separated by a pulse spacing364. A pulse interval362is the length of the transmission of a pulse and a subsequent pulse spacings364.

The pulse structure360ofFIG.3Dillustrates a special case of a frame structure. The pulse structure360illustrates the frame spacing as being the same as the pulse spacing364. In this embodiment, there is no actual physical boundaries between the frames. This timing structure allows sliding window processing where the stride (how often to do the processing) could be selected accordingly. An illustrative example for sliding window366and368of three pulses with a stride of two is shown inFIG.3D.

The pulse structure370ofFIG.3Eillustrates a special case where the sampling of the pulses may not be uniform. For example, pulse372ais separated from pulse372bby pulse spacing374. Similarly, pulse372bis separated from pulse372cby pulse spacing376. The pulse spacing374and the pulse spacing376can be the same or different time durations.

Using variable spacing between pulses and/or frames can increase flexibility and provide coexistence with other systems. For example, consider a 5G system setting, the radar may be constrained by the 5G scheduler on when the radar could operate. By allowing variable spacing, the radar can transmit whenever allowed or not impacting the 5G scheduled time. For another example, consider a WiFi-like system that implements a carrier sensing-based solution. In such a case, the availability of the medium is unknown a priori. The transmitter would have to first listen for transmission in the medium before it can transmit. This kind of uncertainty makes it difficult to guarantee uniform sampling of the pulses and/or frames.

AlthoughFIGS.3A-3Eillustrate electronic device300and radar signals, various changes can be made toFIGS.3A-3E. For example, different antenna configurations can be activated, different frame timing structures can be used or the like.FIGS.3A-3Edo not limit this disclosure to any particular radar system or apparatus.

FIG.4Aillustrates a diagram400of an electronic device with multiple field of view regions corresponding to beams according to embodiments of this disclosure.FIG.4Billustrates a signal processing diagram420for controlling radio frequency (RF) exposure according to embodiments of this disclosure.FIGS.4C and4Dillustrate processes426aand426b, respectively, RF level exposure modifications according to embodiments of this disclosure. The embodiments of the diagram400, the signal processing diagram420, and the process426a, are for illustration only. Other embodiments can be used without departing from the scope of the present disclosure.

The diagram400, as shown inFIG.4Aillustrates an electronic device410. The electronic device410can be similar to any of the client devices106-114ofFIG.1, the server104ofFIG.1, the electronic device200ofFIG.2, or the electronic device300ofFIG.3A.

The electronic device410can include one or more mmWave antenna modules or panels on. The electronic device410can transmit multiple beams corresponding to various regions such as region415a,415b,415c,415d,415e, and415f(collectively regions415). Each beam has a width and a direction. To transmit the beams the electronic device410can include two or more mmWave antenna modules or panels such as an antenna. Other electronic devices can include less or more mmWave antenna modules or panels, such as a single mmWave antenna module or panel.

An RF exposure engine can maintain exposure compliance while minimizing the opportunity loss for communication beamforming operations. One way to achieve such RF exposure control is for the device to be able to know whether there is exposure risk (or whether there is no exposure risk) based on detecting whether there is a body part of a human nearby within one or more of the field-of-view (FoV) regions of the antennas or not.

The signal processing diagram420illustrates an example process for controlling RF exposure. The signal processing diagram420includes several information repositories, including a radar detection results424, a transmission margin428, and transmission configuration history432. These information repositories can be similar to or included within the memory260ofFIG.2. The signal processing diagram420also includes a radar transceiver422, which can be similar to the radar transceiver270ofFIG.2. The signal processing diagram420further includes transceiver430which can be similar to the transceiver210ofFIG.2.

The radar transceiver422transmits and receives radar signals. The received radar signals are used to detect objects which are stored in the radar detection results424. The electronic device logs any detected results in the radar detection results424. The transceiver430logs its adopted transmission configuration such as the transmit power, the beam index used, the duty cycle and the like to the TX configuration history432. Based on (i) whether an object is detected (as indicated in the radar detection results424) and (ii) previous RF exposure levels (as indicated in the TX configuration history432) the RF exposure engine426estimate the worst case RF exposure and derive the transmission margin428. The transmission margin428is a level of RF transmission that would not lead to RF exposure violation, which occurs when a user is exposed to RF above the margin.

It is noted that the update rate of the TX configuration and the radar detection may not be the same. For example, the update rate of the TX configuration could be almost instantaneous (or can practically assume so), while radar detection could be done sporadically due to the constraint on the radar transmission and/or the computational cost for running the radar detection procedure.

The RF exposure engine426can control RF exposure based on a module-level or a beam-level based on radar capability. For example, if the radar cannot detect angle (such as when the electronic device has a single antenna) or lacks enough resolution, the RF exposure engine426may operate the module-level RF exposure management, illustrated inFIG.4C. If the radar has good range resolution and can estimate the angle of the object, the RF exposure engine426may operate using the beam-level RF exposure management, illustrated inFIG.4D.

FIG.4Cillustrates the process426afor the RF exposure engine426ofFIG.4Bto derive the transmission margin428to prevent RF exposure over a predefined limit regarding a module-level RF exposure.

For module-level RF exposure management, the RF exposure engine426, in step440determines, whether a target is within the FoV. The FoV can include multiple regions on one side of the electronic device410, such as the regions415a-415c. When the electronic device does not detect an object within the region415a-415c(based on the results from the radar transmission), the RF exposure engine426in step442can notify the mmWave communication module, (such as the transceiver210ofFIG.2or the transceiver430ofFIG.4B) that is it clear to transmit with no limitations. Alternatively, when the electronic device detects an object that is classified as a human body part (based on the results from the radar transmission and movement of the object), that is within the area defined by the region415a-415c, then the RF exposure engine426in step444notifies the mmWave communication module, (such as the transceiver210ofFIG.2or the transceiver430ofFIG.4B) so that mmWave communication module may reduce the transmit power, revert to using less directional beam, or abort the transmission altogether if the exposure risk is too eminent.

FIG.4Dillustrates the process426bfor the RF exposure engine426ofFIG.4Bto derive the transmission margin428to prevent RF exposure over a predefined limit regarding a beam-level RF exposure.

For the beam-level RF exposure management, the FoV of the module-level RF is divided into smaller FoV regions (the granularity depends on the angle resolution of the radar and expected object (target) size), such as the region415a. The operation is the same as the module-level operation, with the exception that here only when a target is detected within a particular FoV region, such as the region415athat the RF exposure engine426would make adjustment for the affected beams belonging to that FoV region.

For example, the RF exposure engine426, in step450determines whether a target is within the FoV. The FoV can correspond to different beams illustrated by the different regions415. When the electronic device does not detect an object (or detects an object that is determined to not be a human body part), the RF exposure engine426in step452can notify the mmWave communication module, (such as the transceiver210ofFIG.2or the transceiver430ofFIG.4B) that is it clear to transmit with no limitations. Alternatively, when the electronic device detects an object, that is classified as a human body part, the electronic device determines, in step454, which region the object is within. Based on which of the one or more regions415a-415fare blocked, the RF exposure engine426in step in step456a-456n, notifies the mmWave communication module, (such as the transceiver210ofFIG.2or the transceiver430ofFIG.4B) so that mmWave communication module may reduce the transmit power to the particular region, revert to using less directional beam in the particular region, or abort the transmission altogether if the exposure risk is too eminent. For example, if the hand of the user is detected in the region415aand no object is detected in the regions415b-415f, then the mmWave communication module may reduce the power or disable the 5G beams within the region415awhile maintaining a higher transmit power in the regions415b-415fwithout risking any exposure concerns to the user.

AlthoughFIGS.4A-4Dillustrates the electronic device410, the signal processing diagram420, and the processes426aand426b, various changes can be made toFIG.4A-4D. For example, any number of antennas can be used to create any number of regionsFIGS.4A-4Ddoes not limit this disclosure to any particular radar system or apparatus.

FIG.5Aillustrates a method500for beam level exposure management based on object detection according to embodiments of this disclosure.FIG.5Billustrates a method for object detection from step520ofFIG.5Aaccording to embodiments of this disclosure; for object detection.FIG.5Cillustrates a diagram580of an example result of processing two frames for object detection when the object is moving fast according to embodiments of this disclosure. The method500is described as implemented by any one of the client device106-114ofFIG.1, the server104ofFIG.1, the electronic device300ofFIG.3Athe electronic device410ofFIG.4Aand can include internal components similar to that of electronic device200ofFIG.2. However, the method500as shown inFIG.5Acould be used with any other suitable electronic device and in any suitable system, such as when performed by the electronic device200. For ease of explanation,FIGS.5A,5B, and5Care described as being performed by the electronic device200ofFIG.2.

The embodiments of the method500ofFIG.5A, the method ofFIG.5B, and the diagram580ofFIG.5Care for illustration only. Other embodiments can be used without departing from the scope of the present disclosure.

The method500ofFIG.5Adescribes processing a single radar frame. The method500first determines whether there is an object such as a human body part within the FoV of the radar, and then determines the ranges and angles of each detected human body for adjusting the RF exposure level relative to the location of the detected human body part. The method500is described as being performed once per radar frame interval, however depending on the application requirements, system constraint, or the like, it could be desirable to select a different processing interval than the radar frame interval. For example, the processing could be performed once per N radar frames.

In step510, the electronic device200obtains radar measurements. Radar measurements are obtained based on a radar transceiver (such as the radar transceiver270ofFIG.2) transmitting radar signals and receiving reflections of the radar signals. In certain embodiments, the radar measurements are obtained from an information repository (such as the memory260ofFIG.2) which stores previously derived radar measurements.

In step520, electronic device200performs a radar detection to detect an object from the radar measurements. Step520is described in detail inFIG.5B, below. In step540, the electronic device200determines whether an object is detected. If no object is detected (or the detected object is not a human body part), then the electronic device200declares that no object is detected, which is provided to the RF exposure engine426ofFIG.4B(step570).

Alternatively, if a human body part is detected (as determined in step540), the electronic device200estimates the range and angle of the object (step560). For example, if there is at least one object detected, the range and angle of each object is identified. All detected objects along with their attributes (ranges and angles) are provided to the RF exposure engine426ofFIG.4B(step570). The RF exposure engine426can reduce the transmission power, duty cycle, or abort the transmission altogether for certain beams that correspond to the angle(s) of the detected objects. The RF exposure engine426can use other beam directions corresponding to regions where the object is not detected without exposure risk.

FIG.5Bdescribes the step520ofFIG.5Ain greater detail. In particular,FIG.5Bdescribes target detection based on single-frame processing. Moreover,FIG.5Bdescribes detecting a moving object corresponding to a human body part.

In step522, the electronic device200obtains measurements from one radar frame. The step522can obtain the radar measurements from step510ofFIG.5A.

In step524, the electronic device200identifies a Range-Amplitude (RA) map for each pulse of the obtained radar frame. For example, the raw radar measurements are processed (pulse-compression or taking fast-Fourier transform (FFT) for Frequency Modulated Continuous Wave (FMCW) radar) to compute the Complex Impulse Response (CIR) also known as range FFT for FMCW radar, whose amplitude is the RA map. The RA map is a one dimensional signal that captures the amplitude of the reflected power from the reflectors in the FoV of the radar for a finite set of discrete range values (denoted as range tap or tap). This CIR is computed for each pulse separately.

In step526, the electronic device200averages the CIRs from all the pulses within the radar frame to generate the zero-frequency (DC) component as measured by the current processed radar frame. The DC component is the estimate of the reflection from all static objects within the radar's FoV. These static reflections include the leakage (the direct transmission from the radar TX to the radar RX and other reflections off the parts of the radar equipped device) as well as other static objects (relative to the radar) not part of the device housing the radar. In step528, the electronic device200removes (subtracts) the DC component from each pulse.

In step530, the electronic device200averages all resulting RA's to identify the amplitude of each range tap and averaged across all the CIRs. The resulting output is called the range profile, which provide a measure of the amplitude of non-static objects within the radar's FoV for each range tap. In step532, the electronic device200performs the object detection using the range profile by identifying the peaks of the range profile as targets. For example, the electronic device200detects the peaks in the range profile and compares the value at the peak with a detection threshold. The detection threshold can be set according to the noise floor at the particular range tap. For example, the threshold can be set to some number of times the power of the noise floor (such as 3 dB or twice the power of the noise floor). This threshold could be selected to balance misdetection and false alarm rate.

As described above, body parts of a live human can be expected to possess some movements at all times. The movement can be typical body movement (such as intentional hand movement such as grabbing or reaching for something or some unintentional ones such micro movement caused by the muscle reflexes, and the like). Some of the micro movements could be difficult to see visually because of the minor and weak nature of those movement. For radar the sensitivity of the detection of such movement depends on the observation time of the radar signals (which is the radar frame duration in our case). For example, the longer the frame duration is the more sensitive the radar is to the minor movement. Accordingly, the objects being detected as described inFIG.5Bare non-static objects in order to detect a body part of a human to avoid exposing the body part to RF exposure above a certain threshold.

Embodiments of the present disclosure describe using a processing frame that is long enough to provide a sensitivity level, such that body parts are detected with as low misdetection rate. Embodiments of the present disclosure take into consideration that by increasing the transmission interval354ofFIG.3C, can reduce the misdetection rate. However, increasing the transmission interval354is costly in that it increases the radar duty cycle to maintain the same (or similar) frame interval. Additionally, if the radar shares a wireless medium with other systems, a long frame transmission time may create a conflict between the radar and other wireless systems.

In certain embodiments, the processing frame duration can be increased by virtually allowing overlap between the processing frames. This allows for the transmission interval354of a frame to not increase. For example, as shown inFIG.3C, two radar frames can be used within one processing frame interval (such as the processing intervals358aand358b) to increase the observation time of the radar signals used for the detection. With single frame processing, the observation of the radar signal within the processing frame is equal to the frame TX interval. In contrast, by processing two (or more) frames, the processing interval is increased for the duration of each transmission interval354of a frame and the frame spacing interval356between two frames. For example, by processing two radar frames, the observation times is described in Equation (11), below.
(frame TX interval)+(frame spacing)+(frame TX interval)=2×(frame TX interval)+(frame spacing).  (11)

As described in Equation (11) and shown in the processing interval358aofFIG.3C, the processing duration is not just the transmission interval345of two frames (such as frames352aand352b), rather the processing duration is increased due to the silence period in the frame spacing (such as the frame spacing interval356a). Additionally, depending on the detection frequency (one detection per second or the like) the frame spacing could be much larger than the frame TX interval. When the frame spacing is larger than the frame TX interval, the radar observation time for the detection increases without increasing the radar duty cycle.

The electronic device200can determine whether to use a single frame or multiple frames (two or more frames) in a processing interval for detecting movement of the object in order to determine whether to modifying the RF exposure level in area(s) corresponding to the detected object.FIGS.6-12describe various processes for determining whether to use a single frame or multiple frames (two or more frames).

For estimating the angle of the object, first a (spatial) covariance matrix of the object (target) has to be estimated. One way to estimate the covariance matrix is by computing the sample average of the CIR after subtracting the average (0-Doppler removal) at the detected tap index. Equation (12) below defines Xpas the vector of CIR of the p-th pulse at the target tap after the average subtraction of all the radar RX antennas.
Xp=[Xp1,Xp2, . . . ,XpR]T(12)
Here, the radar has R receive antennas, and Xpris the CIR after the average subtraction of the p-pulse received at the r RX antenna. It is noted that in this notation Xpis a column vector of dimension R. P is the number of CIRs (or pulses) of the radar frame, and H is the conjugate transpose operator, then the covariance matrix can be estimated as described in Equation (13), below.

Rxx=1p⁢∑p=1PXp⁢XpH(13)

The difference between the single-frame and the multi-frame processing for the angle estimation is in the number of pulses P used for estimation of Rxx. Note that since the radar transmission timing structure is fixed (the same pulse and frame intervals), using a larger P also means Rxxis averaged over a longer time duration. With this covariance matrix, various angle estimation methods can be used. Some examples include the Bartlett beamforming, the Capon's beamforming (also known as Minimum Variance Distortionless Response MVDR), MUltiple SIgnal Classification (MUSIC), and the like. These methods are what is called the spectrum-based solutions, where the angular spectrum P(θ) is computed and the peaks in P(θ) are the targets and the angles θ corresponding to those peaks are their respective angle estimates. Let α(θ) be the steering vector of the array (normalized), then the angular spectrum for the Bartlett beamforming is described in Equation (14), below. Capon's beamforming is described in Equation (15), below. For MUSIC, beamforming is described in Equations (16) and 17, below.

P⁡(θ)=a⁡(θ)H⁢Rxx⁢a⁡(θ)(14)P⁡(θ)=1a⁡(θ)H⁢Rxx-1⁢a⁡(θ)(15)Rxx=Us⁢Λs⁢UsH+σ2⁢Un⁢UnH(16)P⁡(θ)=1a⁡(θ)H⁢(Un⁢UnH)⁢a⁡(θ),(17)
Here, in Equations (16) and (17) Usand Unare the signal and the noise subspace of Rxx, and Λs(diagonal matrix with eigen values) and σ2(a scalar) are their corresponding eigen values. These can be obtained by performing eigen decomposition of Rxx.

In certain embodiments, the electronic device200determines whether to use a single frame (a current frame) or multi frame (the current frame and one or more additional previous frames) for estimating the covariance matrix. There are two considerations in selecting the frame duration (either to use single frame or to use two frames) to estimate the covariance matrix. The first consideration favors the use of single-frame. The covariance matrix estimate as described above assumes the location change of the object to be small (stay within the same range tap) during the estimation of the covariance matrix. This assumption can be broken when using multi-frame processing, and thus the shorter one like the single-frame is preferred. The second reasoning favors the use of the two frames. When the object's response is weak, the estimation of the covariance matrix will suffer from low SNR and thus longer averaging would help. In our case, the amplitude of the signal is the one after the 0-Doppler removal, and thus the low amplitude likely means that object has little movement and thus the smearing effect due to averaging over longer duration is not of concern.

For object angle estimation, the covariance matrix is first estimated where this covariance matrix is obtained by sample-averaged from the pulses within the radar frame. The typical assumption is that the movement of the object during the frame is negligible that it will not affect the estimation of the covariance matrix. However, with multi-frame processing this is no longer true. An illustrative example of this issue is shown in the diagram580ofFIG.5C. In this example, the target (the hand) is moving away from the device during the measurements. For example, at the first time measurement the hand is at position582, and at the second time measurement the hand moved to position584. Here, the radar frame interval can be about one second with active transmission time of around 0.2 seconds. The graph590describes how using a single frame (the current frame) or multiple frames (the current frame and one or more previous frames) can provide incorrect position of the hand when the hand is moving. Here, in the one second between the first radar frame and the second radar frame, the hand can move several centimeters causing the detected radar peak to fall into a different range tap index (tap 14 as shown inFIG.5D), denoted by line594. In this particular example, if the two frames are used to estimate covariance matrix, it would detect the angle of the target at tap 11 (line592), which is not an actual target but a past image of the hand. In this case, using the current frame (of duration of 0.2 seconds) would provide the correct angle estimation and using multi-frame would provide an incorrect angle estimation.

AlthoughFIGS.5A and5Billustrates one example for detecting a moving object and estimating its location various changes may be made toFIGS.5A and5B. For example, while shown as a series of steps, various steps inFIG.5A,FIG.5B, or both could overlap, occur in parallel, or occur any number of times.

FIGS.6-12illustrate example methods for determining a number of frames for angle estimation according to embodiments of this disclosure. In particular,FIG.6illustrates a method600for determining a number of frames for angle estimation based on a detection status.FIG.7illustrates a method700for determining a number of frames for angle estimation based on a detection status and an amplitude of the detected target.FIG.8illustrates a method800for determining a number of frames for angle estimation based on a detection status and a detected target tap index.FIG.9illustrates a method900for determining a number of frames for angle estimation based on a detection status, a detected target tap index, and an amplitude of the detected target.FIG.10illustrates a method1000for determining a number of frames for angle estimation based on a detection status and a detected target tap index.FIG.11illustrates a method1100for determining a number of frames for angle estimation using more than two frames.FIG.12illustrates a method1200for determining a number of frames for angle estimation using three frames. The embodiments of the method600ofFIG.6, the method700ofFIG.7, the method800ofFIG.8, the method900ofFIG.9, the method1000ofFIG.10, the method1100ofFIG.11, and the method1200ofFIG.12are for illustration only. Other embodiments can be used without departing from the scope of the present disclosure.

The methods600,700,800,900,1000,1100, and1200are described as implemented by any one of the client device106-114ofFIG.1, the server104ofFIG.1, the electronic device300ofFIG.3Athe electronic device410ofFIG.4Aand can include internal components similar to that of electronic device200ofFIG.2. For ease of explanation, methods600through1200are described as being performed by the electronic device200ofFIG.2.

The method600ofFIG.6describes a process for determining whether to use a single frame or two frames for angle estimation based on detection status. For example, if the object is detected by the current single frame (such as when the current frame, denoted as dcur, is true), then the single radar frame is used for covariance matrix estimation. Otherwise, if the two frames detects the object (such as the current frame and a previous frame), then the two frames are used for angle estimation. Note that in this case, when the object is detected by the single-frame processing, then the two-frame processing is skipped, reducing some computation cost.

In step602, the electronic device200performs object detection using a single radar frame. The single frame is a current frame representing the environment around the electronic device200at a current time instance. In step604, the electronic device200determines whether an object is detected from the single frame. If the electronic device200determines that an object is detected, then in step606, the electronic device200uses the current frame for angle estimation. Alternatively, if the electronic device200determines that an object is not detected, then in step608, the electronic device200performs target detection using two frames. The two frames include the current frame and a previous frame. The previous frame can be the frame that immediately came before the current frame. If an object is detected using the two frames, the electronic device200, in step610, uses the two frames for angle estimation. It is noted that if no object is detected in step608, the electronic device200can notify the RF exposure engine426ofFIG.4B(such as described above in step570ofFIG.5A) that no objects are detected indicating that there is no need to mitigate the RF exposure level.

In certain embodiments, if the object is detected (using either the current frame or multiple frames), indicates that the peak has strong enough SNR such that an accurate angle between the electronic device and the location of the object can be identified.

The method700ofFIG.7describes a process for determining whether to use a single frame or two frames for angle estimation based on the detection status and the amplitude of the detected target. The amplitude level corresponds to an amount of movement of a detected object. Therefore, if a single frame has a large amplitude, it indicates that the single frame is preferred for angle estimation to avoid a smearing effect. Alternatively, if the single frame has a small amplitude, it indicates that movement is small or non-existent and therefore two frames should be used to detect whether the object moves.

It is noted that the method700modifies the method600ofFIG.6to include the amplitude of the detected object when the object is detected using a single (current) frame. For example, when the object is detected by the current single frame, the amplitude is checked to see if it is strong enough (the threshold for this could be the detection threshold plus some positive offset). If the detected object has strong signal, the single-frame is used, otherwise two frames are used. The reason is that if the detected peak by the single frame is strong, it means that it corresponds to a fast movement, and thus it can be expected that the covariance matrix estimated over a shorter duration has more fidelity and thus the single-frame is preferred. On the contrary, if the detected object is weak, there likely is little movement and thus the two-frame processing could be used to boost the SNR of the covariance matrix estimate.

In step702, the electronic device200performs target detection using a single frame. The single frame is a current frame representing the environment around the electronic device200at a current time instance. In step704, the electronic device200determines whether an object is detected from the single frame. If the electronic device200determines that an object is detected, then in step706, the electronic device200compares the amplitude of the detected object to a threshold. If the amplitude of the detected object is greater than the threshold, the electronic device200uses the current frame for angle estimation (step708).

Alternatively, if the electronic device200determines that (i) an object is not detected (in step704) or (ii) the amplitude of the detected object is less than or equal to the threshold (in step706), then in step710, the electronic device200performs target detection using two frames. The two frames include the current frame and a previous frame. The previous frame can be the frame that immediately came before the current frame. If an object is detected using the two frames, the electronic device, in step712, uses the two frames for angle estimation. It is noted that if no object is detected in step710, the electronic device200can notify the RF exposure engine426ofFIG.4B(such as described above in step570ofFIG.5A) that no objects are detected indicating that there is no need to mitigate the RF exposure levels.

The method800ofFIG.8describes a process for determining whether to use a single frame or two frames for angle estimation based on detection status and detected target tap index. Instead of the amplitude (as described inFIG.7above), another option is to use the detected tap index for determining whether to use a single frame (a current frame) or two frames. Here, if an object is detected by single-frame (current frame) processing, then the electronic device200also determines whether the detected peak is the same for both single-frame and two-frame processing. If detected peak is the same for both single-frame and two-frame processing, then two frame would be used for angle estimation. If they are not, the single-frame process is used instead. Note that when they are not, it could be that there was some movement large enough to cause the object to change in the peak location and thus it is best to use a shorter frame for accurate angle estimation.

As used inFIG.8, the expression dcurand d2are the detection status of particular frames, which can be a true (indicating that the single (current) frame dcuror the two frames detect the object) or false (indicating that the single (current) frame dcuror the two frames do not detect the object). Additionally, the expression pcuris the tap index of the detected object of the single (current) frame and p2is the tap index of the detected object of from the two frames.

In step802, the electronic device200determines whether the object is detected using the single (current) frame or two frames (the current frame and frame that preceded the current frame). If the object is not detected in either of the single frame or the two frames, then the electronic device200, in step804, determines that no object is detected. The electronic device200can notify the RF exposure engine426ofFIG.4B(such as described above in step570ofFIG.5A) that no objects are detected indicating that there is no need to mitigate the RF exposure levels.

Alternatively, if the electronic device200determines that an object is detected in either of the single (current) frame or two frames, then in step806, the electronic device200determines whether an object is detected from the single frame (when dcuris true). If the electronic device200determines that an object is detected from the single frame, then in step808, the electronic device200determines whether detected peak is the same for both single-frame and two-frame processing. If detected peak is not the same for both single-frame and two-frame processing, then the electronic device200uses the current frame for angle estimation (step810). If (i) the object is not detected in the current frame (as determined in step806, such as when the object is detected using both the current frame and its previous frame) or (ii) the detected peak is the same for both single-frame and two-frame processing (as determined in step808), then the electronic device200, in step812, uses the two frames for angle estimation.

The method900ofFIG.9describes a process for determining whether to use a single frame or two frames for angle estimation based on the detection status, the amplitude of the detected object, and the detected object tap index. It is noted that the method900combines various aspects of the method600ofFIG.6, the method700ofFIG.7, and the method800ofFIG.8.

In this example, the amplitude of the object detected using the current single-frame processing. If the amplitude is strong enough, then the SNR is not an issue so that averaging over the shorter single-frame processing should be sufficient and can save some processing power. In this case, the current single-frame is used for angle estimation and there is no need to perform the two-frame processing (both for target detection and for angle estimation). If there is no object detected in the current frame or if the amplitude of the detected object is not strong enough by the single-frame processing, then two-frame target detection is conducted. For the case when the single-frame detects an object, the peak index detected by the single-frame and the two-frame are compared. If they match, the two frames are used for angle estimation, otherwise the single-frame is used for angle estimation. If the single-frame does not detect an object, then the two-frame object detection is performed, and if an object is detected, then the two frames are used for angle estimation.

In step902, the electronic device200performs target detection using a single (the current) frame. In step904, the electronic device200determines whether an object is detected from the single (current) frame. If the electronic device200determines that an object is detected using the current frame, then in step906, the electronic device200compares the amplitude of the detected object to a threshold. If the amplitude of the detected object is greater than the threshold, the electronic device200uses the current frame for angle estimation (step908).

If the electronic device200determines that an object is not detected in the current frame (as determined in step904), then in step916the electronic device200performs target detection using two frames. The two frames include the current frame and a previous frame. The previous frame can be the frame that immediately came before the current frame. If an object is detected using the two frames, the electronic device, in step914, uses the two frames for angle estimation.

If the electronic device200determines that the amplitude of the detected object is less than or equal to the threshold (as determined in step906), then in step910, the electronic device200performs target detection using two frames (similar to the step916). The two frames include the current frame and a previous frame. The previous frame can be the frame that immediately came before the current frame. Upon detecting the object in step910, the electronic device200determines, in step912, determines whether detected peak is the same for both single-frame and two-frame processing. If detected peak is not the same for both single-frame and two-frame processing, then the electronic device200uses the current frame for angle estimation (step908). Alternatively, if the detected peak is the same for both single-frame and two-frame processing (as determined in912), then the electronic device200, in step914, uses the two frames for angle estimation.

It is noted that if no object is detected in step910or step916, the electronic device200can notify the RF exposure engine426ofFIG.4B(such as described above in step570ofFIG.5A) that no objects are detected indicating that there is no need to mitigate the RF exposure levels.

The method1000ofFIG.10describes a process for determining whether to use a current single frame, a previous single frame, or both the current and previous frames for angle estimation based on detection status and detected target tap index. It is noted that the method1000considers the current single-frame and the two-frame of the current processing frame, but also the previous single-frame (the first part of the two-frame).

As used inFIG.10, the expression dcuris the detection status of a current frame, pprevis the detection status of a previous frame, and d2is the detection status of both the current and previous frame. Additionally, the expression pcuris the tap index of the detected object of the current frame, pprevis the tap index of the detected object of the previous frame, and p2is the is the tap index of the both the current and previous frames. The previous frame can be the frame that immediately came before the current frame.

For example, when the current single-frame can detect the object (such as when dcuris true), the steps are the same as the embodiment describedFIG.8. The difference is when dcuris false. In this case, the electronic device200checks the previous single-frame and follow a similar process as for the current single frame. The rationale for this is that if the object is not detected by the current single-frame, it is likely that there is not much movement. Therefore, using the previous single-frame is better because using the two-frames would likely just be an average over the noise for those pulses corresponding to the current single-frame which could harm the SNR. It is noted that for the case of estimating using the previous single-frame, the electronic device200could just output the angle estimated in the previous processing frame and there is no need to redo the estimation. Further extension by using the amplitude instead of the target tap index or using both amplitude and the target tap index could be done similarly as in the embodiments described above.

In step1002, the electronic device200determines whether the object is detected using the current frame or two frames (the current frame and frame that preceded the current frame). If the object is not detected in either of the current frame or the two frames, then the electronic device200, in step1004, determines that no object is detected. The electronic device200can notify the RF exposure engine426ofFIG.4B(such as described above in step570ofFIG.5A) that no objects are detected indicating that there is no need to mitigate the RF exposure levels.

Alternatively, if the electronic device200determines that an object is detected in either of the current frame or two frames (the current frame and the previous frame), then in step1006, the electronic device200determines whether an object is detected from the current frame (whether dcuris true). If the electronic device200determines that an object is detected from the current frame, then in step1008, the electronic device200determines whether detected peak is the same for both current-frame and two-frame processing. If detected peak is not the same for both current-frame and two-frame processing, then the electronic device200uses the current frame for angle estimation (step1010). However, if the detected peak is the same for both current-frame and two-frame processing (as determined in step1008), then the electronic device200, in step1012, uses the two frames for angle estimation.

If the electronic device200determines, in step1006, that no object is detected from the current frame, then in step1014, the electronic device200determines whether an object is detected from the previous frame. If the object is not detected in the previous frame (as determined in step1014) then the electronic device200, in step1012, uses the two frames for angle estimation. Alternatively, if the object is detected in the previous frame (as determined in step1014) then the electronic device200, in step1016, determines whether detected peak is the same for both previous-frame and two-frame processing. If detected peak is not the same for both previous-frame and two-frame processing, then the electronic device200uses the previous frame for angle estimation (step1018). However, if the detected peak is the same for both previous-frame and two-frame processing (as determined in step1016), then the electronic device200, in step1012, uses the two frames for angle estimation.

It is noted that the methods600,700,800,900and1000are described with respect to detecting a single object. These methods are not limited to a single object. Rather, these methods can be used for each detected object.

Additionally, the methods ofFIGS.6through9can be extended to more than two frames, as shown in the method1100as illustrated inFIG.11. For example,FIG.11describes an example process of determining a number of frames for angel estimation, to use up to k frames, where k is an integer.

In step1102, the electronic device determines whether an object is detected. If the object is not detected, then in step1104, the electronic device determines that no object is detected. The electronic device200can then notify the RF exposure engine426ofFIG.4B(such as described above in step570ofFIG.5A) that no objects are detected indicating that there is no need to mitigate the RF exposure levels.

If the object is detected (as determined in step1102), the electronic device in step1106, determines whether to use the current frame for angle estimation. If the electronic device200determines to use the current frame for angle estimation, then in step1108, the electronic device200uses the current frame for angle estimation. Alternatively, if the electronic device200determines to not use the current frame for angle estimation, then in step1110, the electronic device200determines whether to use the two frames for angle estimation. If the electronic device200determines to use the two frames for angle estimation, then in step1112, the electronic device200uses the two frame for angle estimation. Alternatively, if the electronic device200determines to not use the two frame for angle estimation, the process continues to determine a number of frames to use for angle estimation, similar to the steps1106and1110. At step1114, the electronic device200determines whether to use the less frame than the maximum number of frames (k) for angle estimation. Upon determining to use one less than the maximum number of frames, then the electronic device uses those frames for angle estimation (step1116). Alternatively, the electronic device uses all of the frames (k frames) for angle estimation (step1118).

Since there can be more than two frames, as described in the method1100ofFIG.11, the method1200ofFIG.12describes an example where the number of frames, k, is set to three. It is noted that the method1200expands the method800ofFIG.8from two frames to three frames.

As used inFIG.12, the expression dcuris the detection status of a current frame. The expression pcuris the tap index of the detected object of the current frame. The expression d2is the detection status of two frames (the current frame and frame that preceded the current frame). The expression p2is the is the tap index when using two-frame processing (the current and second frame). The expressions d3and p3are the detection status and the detected peak, respectively, when using three-frame processing.

In step1202, the electronic device200determines whether the object is detected using the current frame, two frames, or three frames. If the object is not detected in any of the frames, then the electronic device200, in step1204, determines that no object is detected. The electronic device200can notify the RF exposure engine426ofFIG.4B(such as described above in step570ofFIG.5A) that no objects are detected indicating that there is no need to mitigate the RF exposure levels.

Alternatively, if the electronic device200determines that an object is detected in any of the frames, then in step1206, the electronic device200determines whether an object is detected from the current frame. If the electronic device200determines that an object is detected from the current frame, then in step1208, the electronic device200determines whether detected peak is the same for both single-frame and two-frame processing. If detected peak is not the same for both single-frame and two-frame processing, then the electronic device200uses the current frame for angle estimation (step1210).

If (i) the object is not detected in the current frame (as determined in step1206) or (ii) the detected peak is the same for both single-frame and two-frame processing (as determined in step1208), then the electronic device200, in step1212, determines whether the object is detected from the two frames (the current frame and the frame that preceded the current frame). If the object is not detected in the two frames (as determined in step1212) then the electronic device200, in step1214, uses the three frames for angle estimation.

Alternatively, if the object is detected in the two frames (as determined in step1212) then the electronic device200, in step1216determines whether detected peak is the same for both two-frame and three-frame processing. If detected peak is not the same for both two-frame and three-frame processing, then the electronic device200uses the two frames for angle estimation (step1218). If detected peak is the same for both two-frame and three-frame processing, then the electronic device200uses the three frames for angle estimation (step1218).

AlthoughFIGS.6-12illustrates various examples for determining the number of frames to use for angle estimation various changes may be made toFIGS.6-12. For example, while shown as a series of steps, various steps inFIGS.6-12could overlap, occur in parallel, or occur any number of times.

FIG.13illustrates an example method1300for modifying radio frequency exposure levels based on an identified angle between an electronic device and an object according to embodiments of this disclosure. The method1300is described as implemented by any one of the client device106-114ofFIG.1, the electronic device300ofFIG.3Athe electronic device410ofFIG.4Aand can include internal components similar to that of electronic device200ofFIG.2. However, the method1300as shown inFIG.13could be used with any other suitable electronic device and in any suitable system, such as when performed by the electronic device200.

In step1302, the electronic device200transmits signals for object detection. The electronic device200can also receive the transmitted signals that reflected off of an object via a radar transceiver, such as the radar transceiver270ofFIG.2. In certain embodiments, the signals are radar. The signals are used to detect an object with regions that expand from the electronic device.

In certain embodiments, the radar signals can be transmitted in frames that are separated by frame spacings. The transmission interval of a frame can be shorter than the frame spacing. The radar frames can include non-uniformly spaced radar pulses or uniformly spaced radar pulses.

In step1304, the electronic device200detects an object using a single radar frame or multiple radar frames based on the transmitted signals. The electronic device200can detect an object based on reflections of the transmitted signals. In certain embodiments, the object is a body part of the user. The electronic device200can distinguish a body part from an inanimate object based on motion. For example, the longer the frame (or multiple frames separated by frame spacings) the electronic device200can identify motion from a detected object. When motion is present the electronic device can classify the object as a body part for which RF exposure need to be monitored and adjusted. Alternatively, if the electronic device200does not detect motion, then the RF exposure does not need to be monitored and the electronic device does not need to identify the angle between the object and the electronic device200.

In step1306, the electronic device200determines whether to use a single radar frame or multiple radar frames for angle identification. The determination of whether to use a single radar frame or multiple radar frames for angle identification can be based on a detection status of the body part using the single radar frame or the multiple radar frames. The determination of whether to use a single radar frame or multiple radar frames for angle identification can be based on a magnitude of a peak amplitude of the radar signals, the magnitude representing whether the body part is stationary or moving. The determination of whether to use a single radar frame or multiple radar frames for angle identification can be based on a change in location of the body part.

In step1308, the electronic device200identifies the angle between the object and the electronic device200using a single radar frame or the multiple radar frames. For example, based on a determination to use the single radar frame, the electronic device200identifies the angle between the object and the electronic device using a single radar frame. For another example, based on a determination to use the multiple radar frames, the electronic device200identifies the angle between the object and the electronic device200using multiple radar frames.

In certain embodiments, the electronic device200identifies the angle between the object and the electronic device200using covariance values obtained based on averaging pulses within the one or more radar frames.

In step1310, the electronic device200modifies the exposure level at one or more regions based on the identified angle that the object is relative to the electronic device200.

AlthoughFIG.13illustrates example methods, various changes may be made toFIGS.13. For example, while the method1300is shown as a series of steps, various steps could overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, steps may be omitted or replaced by other steps.

The above flowcharts illustrate example methods that can be implemented in accordance with the principles of the present disclosure and various changes could be made to the methods illustrated in the flowcharts herein. For example, while shown as a series of steps, various steps in each figure could overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, steps may be omitted or replaced by other steps.

Although the figures illustrate different examples of user equipment, various changes may be made to the figures. For example, the user equipment can include any number of each component in any suitable arrangement. In general, the figures do not limit the scope of this disclosure to any particular configuration(s). Moreover, while figures illustrate operational environments in which various user equipment features disclosed in this patent document can be used, these features can be used in any other suitable system. None of the description in this application should be read as implying that any particular element, step, or function is an essential element that must be included in the claims scope.

Although the present disclosure has been described with an exemplary embodiment, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.