Patent Description:
Radar operates to localize targets in the radar field of view in terms of range and/or angle (azimuth and/or elevation) and/or velocity. For certain types of radars, the transmitter and the receiver can be installed closely together, resulting in signals that are transmitted by the transmitter being received directly by the receiver or bounced off some component or components of the device to reach the receiver. This signal is referred to as a leakage signal. The leakage signal interferes with radar detection and ranging. Due to the presence of sometimes strong leakage signals, detection or range estimation is challenging. In particular, detection or range estimation is challenging for close-range distances of comparable values to the separation between the transmitter and the receiver because the leakage masks the actual target object. Detection at a close range can be compromised due to strong leakage that can mask the target. Even assuming the detection is successful, range estimation can be inaccurate due to the leakage distorting the target response.

<CIT> describes a cancellation system for millimeter-wave radar.

One way to overcome this challenge is to compensate for or cancel the leakage signals. Cancelation of leakage signals helps to enable reliable detection of a target object and accurate estimation of the range of the target in the proximity range of the radar. The proximity range generally refers to distances below <NUM>, such as below <NUM>. The radar as described herein can operate at various frequency bands including, but not limited to, <NUM> - <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

Current methods of separating the contribution of the leakage from the contribution of the target assume that either the target contribution or the leakage contribution can be suppressed by some means. For example, current methods utilize knowledge of the target location, control the changing of the location of the target, or control the suppressing target contribution to received signal.

Embodiments of the present disclosure include a method and an electronic device for leakage cancelation. In one embodiment, there is provided an electronic device as defined by claim <NUM> of the claims appended hereto.

In another embodiment, there is provided a method of canceling leakage as defined by claim <NUM> of the claims appended hereto.

For a more complete understanding of this disclosure and its advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:.

<FIG>, discussed below, and the various embodiments used to describe the principles of the present disclosure are by way of illustration only.

<FIG> illustrates an electronic device according to various embodiments of the present disclosure. The embodiment of the electronic device <NUM> shown in <FIG> is for illustration only. Other embodiments can be used without departing from the scope of the present disclosure.

As shown in <FIG>, the electronic device <NUM> includes a radio frequency (RF) transceiver <NUM>, transmit (TX) processing circuitry <NUM>, a microphone <NUM>, receive (RX) processing circuitry <NUM>, a speaker <NUM>, a processor <NUM>, an input/output (I/O) interface (IF) <NUM>, a memory <NUM>, a display <NUM>, an input <NUM>, and sensors <NUM>.

The transceiver <NUM> transmits signals to other components in a system and receives incoming signals transmitted by other components in the system. For example, the transceiver <NUM> transmits and receives RF signals, such as BLUETOOTH or WI-FI signals, to and from an access point (such as a base station, WI-FI router, BLUETOOTH device) of a network (such as a WI-FI, BLUETOOTH, cellular, <NUM>, LTE, LTE-A, WiMAX, or any other type of wireless network). The received signal is processed by the RX processing circuitry <NUM>. The RX processing circuitry <NUM> may transmit the processed signal to the speaker <NUM> (such as for voice data) or to the processor <NUM> for further processing (such as for web browsing data). The TX processing circuitry <NUM> receives voice data from the microphone <NUM> or other outgoing data from the processor <NUM>. The outgoing data can include web data, e-mail, or interactive video game data. The TX processing circuitry <NUM> processes the outgoing data to generate a processed signal. The transceiver <NUM> receives the outgoing processed signal from the TX processing circuitry <NUM> and converts the received signal to an RF signal that is transmitted via an antenna. In other embodiments, the transceiver <NUM> can transmit and receive radar signals to detect the potential presence of an object in the surrounding environment of the electronic device <NUM>.

In this embodiment, one of the one or more transceivers in the transceiver <NUM> includes a radar transceiver <NUM> configured to transmit and receive signals for detection and ranging purposes. For example, the radar transceiver <NUM> may be any type of transceiver including, but not limited to a WiFi transceiver, for example, an <NUM>. 11ay transceiver. The radar transceiver <NUM> includes an antenna array <NUM> that includes transmitter <NUM> and receiver <NUM> antenna arrays. The transmitter <NUM> can transmit signals at frequencies including, but not limited to, <NUM> - <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. In some embodiments, the signals transmitted by the radar transceiver <NUM> can include, but are not limited to, millimeter wave (mmWave) signals. The radar transceiver <NUM> can receive the signals, which were originally transmitted from the radar transceiver <NUM>, after the signals have bounced or reflected off of target objects in the surrounding environment of the electronic device <NUM>. The processor <NUM> can analyze the time difference between when the signals are transmitted by the radar transceiver <NUM> and received by the radar transceiver <NUM> to measure the distance of the target objects from the electronic device <NUM>.

The transmitter <NUM> and the receiver <NUM> can be fixed near in proximity to each other such that the distance of separation between them is small. For example, the transmitter <NUM> and the receiver <NUM> can be located within a few centimeters of each other. In some embodiments, the transmitter <NUM> and the receiver <NUM> can be co-located in a manner that the distance of separation is indistinguishable. Based on the fixed, constant spatiotemporal relationship of the transmitter <NUM> and the receiver <NUM>, the processor <NUM> can use information regarding the spatiotemporal relationship of the transmitter <NUM> and the receiver <NUM> to cancel leakage, such as radar leakage, in a response signal resulting from a transmitted radar signal leaking to the receiver <NUM>. For example, the response signal can be a channel impulse response (CIR) as further described herein in <FIG>.

The transceiver <NUM> receives the outgoing processed baseband or IF signal from the TX processing circuitry <NUM> and up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna.

The processor <NUM> is also capable of executing the operating system <NUM> in the memory <NUM> in order to control the overall operation of the electronic device <NUM>. For example, the processor <NUM> can move data into or out of the memory <NUM> as required by an executing process. In some embodiments, the processor <NUM> is configured to execute the applications <NUM> based on the OS program <NUM> or in response to signals received from external devices or an operator. In some embodiments, the memory <NUM> is further configured to store data, such as one or more leakage factors, that the processor <NUM> can utilize to perform leakage cancelation as described herein. In some embodiments, the processor <NUM> can control the reception of forward channel signals and the transmission of reverse channel signals by the transceiver <NUM>, the RX processing circuitry <NUM>, and the TX processing circuitry <NUM> in accordance with well-known principles.

The processor <NUM> is also coupled to the I/O interface <NUM>, the display <NUM>, the input <NUM>, and the sensor <NUM>. The I/O interface <NUM> provides the electronic device <NUM> with the ability to connect to other devices such as laptop computers and handheld computers. The I/O interface <NUM> is the communication path between these accessories and the processor <NUM>. The display <NUM> can 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 processor <NUM> can be coupled to the input <NUM>. An operator of the electronic device <NUM> can use the input <NUM> to enter data or inputs into the electronic device <NUM>. Input <NUM> can be a keyboard, touch screen, mouse, track-ball, voice input, or any other device capable of acting as a user interface to allow a user in interact with electronic device <NUM>. For example, the input <NUM> can include voice recognition processing thereby allowing a user to input a voice command via microphone <NUM>. For another example, the input <NUM> can 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 among a capacitive scheme, a pressure sensitive scheme, an infrared scheme, or an ultrasonic scheme.

The electronic device <NUM> can further include one or more sensors <NUM> that meter a physical quantity or detect an activation state of the electronic device <NUM> and convert metered or detected information into an electrical signal. For example, sensor(s) <NUM> may include one or more buttons for touch input, one or more cameras, a gesture sensor, an eye tracking sensor, a gyroscope or gyro sensor, an air pressure sensor, a magnetic sensor or magnetometer, an acceleration sensor or accelerometer, a grip sensor, a proximity sensor, a color 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 infrared (IR) sensor, an ultrasound sensor, a fingerprint sensor, and the like. The sensor(s) <NUM> can further include a control circuit for controlling at least one of the sensors included therein.

In various embodiments, the electronic device <NUM> may be a phone or tablet. In other embodiments, the electronic device <NUM> may be a robot or any other electronic device using a radar transceiver <NUM>. does not limit the present disclosure to any particular type of electronic device.

<FIG> illustrates a monostatic radar according to various embodiments of the present disclosure. The embodiment of the monostatic radar <NUM> shown in <FIG> is for illustration only. Other embodiments can be used without departing from the scope of the present disclosure. The monostatic radar <NUM> illustrated in <FIG> includes a processor <NUM>, a transmitter <NUM>, and a receiver <NUM>. In some embodiments, the processor <NUM> can be the processor <NUM> of <FIG>.

In some embodiments, the transmitter <NUM> and the receiver <NUM> can be the transmitter <NUM> and receiver <NUM>, respectively, included in the antenna arrays <NUM> of <FIG>. In various embodiments, the transmitter <NUM> and the receiver <NUM> are co-located using a common antenna or nearly co-located while separate but adjacent antennas. The monostatic radar <NUM> is assumed to be coherent such that the transmitter <NUM> and the receiver <NUM> are synchronized via a common time reference.

The processor <NUM> controls the transmitter <NUM> to transmit a radar signal or radar pulse. The 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 (shown as a parabolic antenna), such as the transmitter <NUM>, either omni-directionally or focused into a particular direction. After the radar pulse has been transmitted, a target <NUM> at a distance R from the radar <NUM> and within a field-of-view of the transmitted pulse will be illuminated by RF power density Pt (in units of W/m<NUM>) for the duration of the transmission. To the first order, Pt is described by Math <FIG>(Equation <NUM>): <MAT> where PT is a transmit power [W], GT is a transmit antenna gain [dBi], AT is an effective aperture area [m<NUM>], λ is a wavelength of the radar signal RF carrier signal [m], and R is the target distance [m].

The transmit power density impinging onto the target surface leads to reflections depending on the material composition, surface shape, and dielectric behavior at the frequency of the radar signal. Off-direction scattered signals are generally not strong enough to be received back at the receiver <NUM>, so only direct reflections contribute to a detectable, received signal. Accordingly, the illuminated area or areas of the target with normal vectors directing back to the receiver <NUM> act as transmit antenna apertures with directivities, or gains, in accordance with their effective aperture area or areas. The reflected-back power Prefl is described by Math <FIG>(Equation <NUM>): <MAT> where Prefl is an effective (isotropic) target-reflected power [W], At is an effective target area normal to the radar direction [m2], rt is a reflectivity of the material and shape [<NUM>,. , <NUM>], Gt is a corresponding aperture gain [dBi], and RCS is a radar cross section [m<NUM>]. As shown in Equation <NUM>, the corresponding aperture gain [dBi] (Gt) is approximately the same as the reflectivity of the material and shape [<NUM>,. , <NUM>] (rt) multiplied by the result of the effective target area normal (At) divided by (i) the wavelength squared divided by (ii) four times π.

As depicted in Equation <NUM>, the radar cross section (RCS) is an equivalent area that scales proportionally to the square of the actual reflecting area, is inversely proportional to the square of the wavelength, and is reduced by various shape factors and the reflectivity of the material itself. For example, for a flat, fully reflecting mirror of an area At, large compared with λ<NUM>, RCS=4π A<NUM>t/λ<NUM>. Due to the material and shape dependency, it is difficult to deduce the actual physical area of the target <NUM> based on the reflected power even if the distance R from the target to the radar <NUM> is known.

The target-reflected power at the location of the receiver <NUM> is based on the reflected-power density at the reverse distance R, collected over the receiver antenna aperture area. The received, target-reflected power PR is described by Math <FIG>(Equation <NUM>): <MAT> where PR is the received, target-reflected power [W] and AR is the receiver antenna effective aperture area [m<NUM>]. In some embodiments, AR can be the same as AT.

Such a radar system is usable as long as the receiver signal exhibits a sufficient signal-to-noise ratio (SNR). The particular value of the SNR depends on the waveform and detection method used. The SNR is described by Math <FIG>(Equation <NUM>): <MAT> where kT is Boltzmann's constant x temperature [W/Hz], B is the radar signal bandwidth [Hz], and F is the receiver noise factor, referring to the degradation of receive signal SNR due to noise contributions to the receiver circuit itself.

In some embodiments, the radar signal can be a short pulse with a duration, or width, denoted by TP. In these embodiments, the delay t between the transmission and reception of the corresponding echo will be equal to τ=<NUM>R/c, where c is the speed of light propagation in the medium, such as air. In some embodiments, there can be several targets <NUM> at slightly different distances R. In these embodiments, the individual echoes of each separate target <NUM> is distinguished as such only if the delays differ by at least one pulse width, and the range resolution of the radar is described as ΔR=cΔτ/<NUM>=cTp/<NUM>. A rectangular pulse of duration TP exhibits a power spectral density P(f)~(sin(πfTP)/(πfTP))<NUM> with the first null at its bandwidth B=<NUM>/TP. Therefore, the connection of the range resolution of a radar with the bandwidth of the radar waveform is described by Math <FIG>(Equation <NUM>): <MAT>.

Based on the reflected signals received by the receiver <NUM>, the processor <NUM> generates a metric that measures the response of the reflected signal as a function of the distance of the target <NUM> from the radar. In some embodiments, the metric can be a channel impulse response (CIR).

<FIG> illustrates an example of a CIR depicting a measured leakage response according to various embodiments of the present disclosure. The CIR is a response metric based on the signals received by the receiver <NUM>. For example, the CIR is a measure of amplitude and/or phase of a reflected signal as a function of distance. As shown in <FIG>, the CIR is depicted with the delay tap index denoted on the x-axis, measuring the distance, and the amplitude of the radar measurement [dB] denoted on the y-axis. In a monostatic radar, for example the radar <NUM>, that has separate transmitting and receiving antenna modules, a strong signal can radiate directly from the transmitter <NUM> to the receiver <NUM> causing a strong response at the delay corresponding to the separation between the transmitter <NUM> and receiver <NUM>. The strong signal radiating from the transmitter <NUM> to the receiver <NUM> is referred to as a leakage signal. Even if the direct leakage signal from the transmitter <NUM> can be assumed to correspond to a single delay, the effect of the direct leakage signal can still impact multiple delay taps adjacent to the direct leakage signal.

In the measured leakage response illustrated in <FIG>, the main leakage peak is denoted at tap <NUM>. In addition, taps <NUM> and <NUM> also have strong responses, noted by the responses being greater than <NUM> dB above the noise floor. Because of the additional responses such as shown at taps <NUM> and <NUM>, it is difficult to reliably detect and estimate the target range within those first few taps from the leakage taps.

<FIG> illustrates a timing diagram for radar transmission according to various embodiments of the present disclosure. In particular, <FIG> illustrates a frame structure that divides time into frames. Each frame comprises multiple bursts. Each burst includes a plurality of pulses. The timing diagram illustrated in <FIG> assumes an underlying pulse compression radar system.

As illustrated in <FIG>, each frame includes a number of bursts N, illustrated as Burst <NUM>, Burst <NUM>, Burst <NUM>, etc. Each burst further includes a plurality of pulses. For example, <FIG> illustrates that Burst <NUM> comprises a plurality of pulses referenced as Pulse <NUM>, Pulse <NUM>, etc. through Pulse M.

For example, in Burst <NUM>, a radar transceiver, such as the transmitter <NUM>, can transmit Pulse <NUM>, Pulse <NUM>, and Pulse M, where M represents the final pulse in the burst. For simplicity of description, the present description assumes Pulse M is a third pulse, but this description should not be construed as limiting. In various embodiments, M can be a third pulse or any number of pulses. In Burst <NUM>, the transmitter <NUM> can transmit similar pulses Pulse <NUM>, Pulse <NUM>, and Pulse M. Each different pulse (Pulse <NUM>, Pulse <NUM>, and Pulse M) and burst (Burst <NUM>, Burst <NUM>, Burst <NUM>, etc.) can utilize a different transmission/reception antenna configuration, that is the active set of antenna elements and corresponding analog/digital beamforming weights, to identify the specific pulses and bursts. For example, each pulse or burst can utilize a different active set of antenna elements and corresponding analog/digital beamforming weights to identify specific pulses and bursts.

Following each frame, a processor, such as the processor <NUM>, connected to the transmitter <NUM> obtains radar measurements at the end of each frame. For example, the radar measurements can be depicted as a three-dimensional complex CIR matrix. The first dimension may correspond to the burst index, the second dimension may correspond to the pulse index, and the third dimension may correspond to the delay tap index. The delay tap index can be translated to the measurement of range or time of flight of the received signal.

Several types of leakage cancelation methods that leverage the relationship between one or more transmitting and receiving antenna pairs across space and time can be utilized as described in the present disclosure. The leakage cancelation methods described herein exploit the constant relationship between the transmitting and receiving antenna pairs to reconstruct the leakage signals from past observations of the same antenna pair or current measurements as seen by other transmit and receive antenna pairs. These embodiments are broadly illustrated in <FIG>.

<FIG> illustrates a method for target detection and ranging according to various embodiments of the present disclosure. The embodiment of the method <NUM> shown in <FIG> is for illustration only. Other embodiments that include additional operations or fewer operations can be used without departing from the scope of the present disclosure.

In operation <NUM>, radar measurements are obtained as described in greater detail herein. The radar measurements can include storing data regarding the fixed positions of the transmitting and receiving antenna pairs in the memory <NUM> as well as obtaining a CIR profile as described in <FIG>.

In operation <NUM>, the processor <NUM> performs leakage cancelation. The leakage cancelation can be performed based on information regarding the stored relationship between one or more transmitting and receiving antenna pairs across space and time, previous leakage cancelation operations, and the obtained CIR such as the CIR illustrated in <FIG>. The leakage cancelation cancels the raw radar received signals that correspond to leakage rather than a target. In some embodiments, operation <NUM> can include additional steps such as combining leakage of one or more antenna pairs, utilizing a stored leakage factor stored in a template in the memory <NUM>, and performing presence detection of a potential target object in the surrounding environment of the electronic device <NUM>. Various embodiments of performing leakage cancelation will be further described herein.

In operation <NUM>, the processor <NUM> performs target detection and ranging based on the results of the leakage cancelation. For example, the processor <NUM> can detect a target based on a peak remaining in the CIR after the leakage has been canceled. The processor <NUM> can further determine the distance of the detected target based on the tap index as shown in the CIR illustrated in <FIG>.

The method of target detection and ranging described in <FIG> is not restricted to target detection but also can be used for non-conventional use such as context detection. The method of target detection and ranging described in <FIG> further does not rely on movement of either the target or electronic device <NUM> and is robust to changes in leakage, for example common phase and amplitude jumps.

<FIG> illustrates a transmission antenna array and a reception antenna array according to various embodiments of the present disclosure. In particular, <FIG> illustrates a transmission antenna array <NUM> and a reception antenna array <NUM>. The transmission antenna array <NUM> and reception antenna array <NUM> can be provided in a device such as the electronic device <NUM> or the radar <NUM>. For example, the transmission antenna array <NUM> and reception antenna array <NUM> can be the transmitter <NUM> and receiver <NUM>, respectively, included in the antenna arrays <NUM>. As another example, the transmission antenna array <NUM> can be the transmitter <NUM> and the reception antenna array <NUM> can be the receiver <NUM>.

As illustrated in <FIG>, the transmission antenna array <NUM> includes nine transmission elements (e.g. <NUM>-<NUM>) arranged in a 3x3 pattern. Although depicted as nine transmission elements arranged in a 3x3 pattern, this embodiment should not be construed as limiting and other embodiments are possible. Any suitable quantity of transmission elements can be included, and the transmission elements can be arranged in any suitable configuration. Further, the reception antenna array <NUM> includes nine reception elements (e.g. <NUM>-<NUM>) arranged in a 3x3 pattern. Although depicted as nine reception elements arranged in a 3x3 pattern, this embodiment should not be construed as limiting and other embodiments are possible. Any suitable quantity of reception elements can be included, and the reception elements can be arranged in any suitable configuration.

The transmission antenna array <NUM> and reception antenna array <NUM> are disposed, or installed, on the electronic device <NUM> at fixed positions as illustrated in <FIG>. Regardless of the particular configuration, because of the fixed positions of the transmission antenna array <NUM> and reception antenna array <NUM>, the distance of separation and the angular relationships between the transmission antenna array <NUM> and reception antenna array <NUM> are constant and time-invariant. For example, the transmission antenna array <NUM>-<NUM> maintains a constant distance and angle from the reception antenna array <NUM>-<NUM>, noted by the arrow in <FIG>. By positioning the transmission antenna array <NUM> and reception antenna array <NUM> in a fixed, constant, and time-invariant position, the transmission antenna array <NUM> and reception antenna array <NUM> can be defined by the constant spatiotemporal relationship that can be used to cancel radar leakage of the transmission antenna array <NUM> and reception antenna array <NUM>.

The distance separation determines the propagation attenuation level and the directional relationship determines the antenna gain (according to the radiation pattern) of the transmission antenna array <NUM> and reception antenna array <NUM>. The propagation attenuation level and the antenna gain are some of the transformations that a leakage signal goes through, beginning with the digital transmit symbol, until the leakage signal is received and demodulated as the digital baseband received signal. Another transformation includes the combined response of the transmit and receive filters, which include the pulse-shaping filter at the transmitter antenna array <NUM> and the matched filter at the reception antenna array <NUM>. The combined response is typically constant as long as the sampling timing remains unchanged. When the transformations are unchanged, they are able to be exploited by the processor <NUM> to reconstruct leakage signals from prior measurements or current measurements as seen by other antenna pairs and can be used to cancel the leakage contribution in the raw radar signals.

In various embodiments, a transmit and receive antenna pair can be referred to as k. for example, element <NUM> of the transmission antenna array <NUM> and element <NUM> of the reception antenna array <NUM> can form an antenna pair and be referred to as k. Another transmit and receive antenna pair can be referred to as l. For example, element <NUM> of the transmission antenna array <NUM> and element <NUM> of the reception antenna array <NUM> can form an antenna pair and be referred to as l. Although k and l are described herein as describing elements <NUM> and <NUM> of both antenna arrays <NUM>, <NUM>, respectively, each of k and l can refer to any pair of transmission and reception antenna arrays.

When the antenna pairs transmit orthogonal transmissions, the leakage Lk for each antenna pair, for example antenna pair k, can be defined by multiplying the antenna gain of the reception antenna, antenna gain of the transmission antenna, propagation loss between the antenna pair, and filter response as seen by the pair. For example, when the CIR of the leakage at the delay tap n is defined as Lk[n], then Lk[n] can be determined by Math <FIG>(Equation <NUM>): <MAT> where n is the delay tap as received via the transmit and receive antenna pair k, GR,k is the antenna gain of the receive antenna, GT,k is the antenna gain of the transmit antenna, αk the propagation loss between the antenna pair, and pk[n] is the combined filter response as seen by the pair. Likewise, the leakage for the antenna pair l can be defined as Ll[n]=G R,l αl GT,l pl[n]. In some embodiments, the leakage measurements Lk[n] can be obtained by measuring the CIRk[n] when there is no target in proximity of the radar.

When the sampling timing between the two antenna pairs k and l is the same, a constant factor between k and l can be determined to more accurately cancel the leakage. The filter response for each pair can be the same because of the constant spatial relationship between the two pairs. The same filter response is denoted as pk[n]=pl[n] for all n. Therefore, the leakage signals as determined by k and l differ by a constant factor, β, determined by Math <FIG>(Equation <NUM>), assuming index n=<NUM> corresponds to the leakage peak: <MAT>.

The constant factor β can also be referred to as a compensation factor β, a scaling factor β, a leakage factor, or a leakage scaling factor β. The leakage factor β can be stored in a template in the memory <NUM> to be used for future determinations. For example, a stored β of the CIR with target contributions that is received by pair l can be used to reconstruct leakage as observed by pair k and accordingly cancel leakage signals from the received CIR of pair k. For example, if CIRk[n] and CIRl[n] denote the CIR received by pair k and pair l, respectively, with target contributions, then a leakage canceled CIR, denoted as CIRcan,k[n], received by pair k can be obtained by Math <FIG>(Equation <NUM>): <MAT>.

The cancelation of Math <FIG>(Equation <NUM>) cancels out leakage because leakage factor β is calculated and stored to match the leakage. The leakage canceled CIR received by pair l can be computed in a similar manner by using l instead of k and using the inverse of β as the scaling factor. For the contribution of a target, this factor does not compensate for different scaling and the target signal is not canceled out. In these embodiments, the canceled CIRcan,k[n] can then be input into a detection and ranging system for further processing. In some embodiments, the canceled CIRcan,k[n] can also be stored for further processing at a later time.

In some embodiments, the cancelation, i.e. subtraction, can be performed for each antenna pair in a range of indices. For example, the cancelation can be performed between element <NUM> of the transmitter antenna array <NUM> and the reception antenna array <NUM> and between element <NUM> of the transmitter antenna array <NUM> and the reception antenna array <NUM>, between element <NUM> of the transmitter antenna array <NUM> and the reception antenna array <NUM> and between element <NUM> of the transmitter antenna array <NUM> and the reception antenna array <NUM>, and so forth. In other embodiments, the cancelation can be performed only for the range of delay tap indices that are expected to be affected by the leakage, denoted by N, rather than for all indices. For indices that are not expected to be affected by the leakage, the original CIR received by the pair k can be maintained. This embodiment is described by CIRcan,k[n]=CIRk[n] for all n∉N. Because the leakage factor β is time-invariant, the leakage factor β can be measured, or precomputed, and then stored in the memory <NUM> for canceling leakage at a later time. For example, the leakage factor β can be measured and stored in a template in the memory <NUM> as a part of the manufacturing process to accurately measure device-specific leakage factors β.

In some embodiments, the combined filter response is not the same for each antenna pair. For example, the difference in the filter response can be due to a difference in the sampling timing of the leakage signal. The sampling timing can be a fractional of the symbol period of the baseband signal. Differences in the sampling timing of the leakage signal can be due to a link distance between the two pairs k and l being great enough to lead to a different exact fractional sampling time of the leakage by the two pairs k and l. This can lead to different combined filter responses. When the combined filter response is different, the leakage is seen by one antenna pair cannot be translated to the leakage observed via another antenna pair by a single leakage factor β and a separate leakage factor β is used for each index. Because the leakage is to be canceled, the scaling factor near the leakage peak index is determined. For a set of indices N, the leakage factor β[n] for the set of indices N in the range can be determined by Math <FIG>(Equation <NUM>): <MAT>.

As shown in Math <FIG>(Equation <NUM>), leakage scaling factor β[n] can be determined by dividing the first CIR for [k] by the second CIR for [l]. In particular, the first CIR for [k] can be generated by the receiver antenna gain GR,k of the first antenna pair, the propagation coefficient αk of the first antenna pair, the transmitter antenna gain GT,l of the first antenna pair, and the transmitter and receiver combined filter response pk[n] of the first antenna pair. Similarly, the second CIR for [l] can be generated by the receiver antenna gain GR,l of the second antenna pair, the propagation coefficient αl of the second antenna pair, the transmitter antenna gain GT,l of the second antenna pair, and the transmitter and receiver combined filter response pl[n] of the second antenna pair.

Once the leakage scaling factor β[n] is obtained, the leakage scaling factor β[n] can be used to cancel the leakage using Math <FIG>(Equation <NUM>): <MAT>.

The leakage factor β[n] is time-invariant because of the fixed spatial relationships between antenna pairs k and l. Therefore, the leakage factor β[n] can be measured and stored in the memory <NUM>. For example, the leakage factor β[n] can be measured and stored in the memory <NUM> as a part of the manufacturing process to accurately measure device-specific leakage factors β[n]. The processor <NUM> can then identify the leakage factor β[n] associated with the antenna pair k and l.

As described above, the leakage CIR is the signal transformed by the antenna gains, the propagation attenuation, and the combined filter response to reach the receiver. A scaling factor θ of a single antenna pair can be determined and used to measure the cancelation of the leakage CIR. The scaling factor θ can also be referred to as a leakage factor θ. The leakage factor θ can be determined by Math Figure <NUM>(Equation <NUM>): <MAT>.

where Lk[n] is the leakage CIR measured beforehand and stored on the device and N is the range of indices expected to be affected by the leakage. Although depicted herein as using the absolute difference between the canceled leakage and the scaling factor multiplied by the leakage CIR measured beforehand and stored on the device, other numerical methods can be used to determine the leakage factor θ. For example, the squared absolute difference or any other kind of distance measurement can also be used.

The leakage factor θ can be used to perform leakage cancelation. For example, the leakage factor θ can perform leakage cancelation when used in Math Figure <NUM>(Equation <NUM>): <MAT>.

In some embodiments, Lk[n] can be measured, or precomputed, and then stored in the memory <NUM> for canceling leakage of a CIR of an additional antenna pair at a later time. In various embodiments, the value of Lk[n] can be described as a leakage factor. In some embodiments, the leakage factor θ can be measured, or precomputed, and then stored in a template stored in the memory <NUM> for canceling leakage of a CIR of an additional antenna pair at a later time. Each leakage factor θ can be stored for different configurations of the electronic device <NUM>, for example when using different transmit power. For example, the leakage factor θ can be measured and stored in the template as a part of the manufacturing process to accurately measure device-specific leakage factors θ. The processor <NUM> can then identify the leakage factor θ associated with the antenna pair to be used later for determining leakage in a CIR. In other embodiments, the leakage factor θ can be computed at the current time as needed in order to adjust the leakage factor θ based on a change in the transmit power.

In some embodiments, a sampling timing can be different when hardware initialization is performed. For more accurate leakage cancelation, rather than storing only one leakage CIR for one fractional sampling timing, the leakage CIR as measured using each fractional sampling timing can be stored in the template. The fractional sampling timing is defined at the receiver <NUM> so the processor <NUM> can adjust the sampling timing to maximize the signal strength. In these embodiments, the sampling timing selected during the initialization procedure can be used to select a corresponding leakage CIR that is stored in the template to be used for the leakage cancelation as described herein.

The processor <NUM> or <NUM> can identify Lk[n] stored in the template in the memory <NUM> that is associated with the particular antenna pair. After the processor <NUM> has controlled the transmitter <NUM> to transmit a first signal and generated a CIR based on the receipt, by the receiver <NUM>, of the reflection of the first signal, the processor <NUM> determines the leakage in the CIR based on the stored Lk[n]. After the leakage of the CIR has been determined, the processor can cancel the determined leakage from the CIR and perform object detection based on the leakage canceled CIR.

In some embodiments, the leakage factor β can be the same as the leakage factor θ. The leakage factor β can also be stored in a template in the memory <NUM> that is the same or different template that stores the leakage factor θ. The processor <NUM> can control a second transmitter <NUM> of a second antenna pair to transmit an additional signal a generate a second CIR based on the receipt, by a second receiver <NUM> of the second antenna pair, of the reflection of the first signal. The processor <NUM> can then determine the leakage of the second CIR based on the leakage factor β and cancel the determined leakage from the second CIR. The processor <NUM> can then perform object detection based on the leakage canceled second CIR.

<FIG> illustrates a method of combining multiple leakage canceled CIRs according to various embodiments of the present disclosure. In some embodiments, the processor <NUM> can utilize M antenna pairs rather than one or two pairs of antennas k or l as described in <FIG>, where M represents the number of antenna pairs. Using M antenna pairs rather than a single pair provides multiple estimates of the CIR after the leakage cancelation. The multiple estimates can be combined for better performance, such as an improvement in the signal-to-noise ratio, before the processor <NUM> performs the detection and ranging procedure.

The number of groupings of two pairs can be selected in various ways. For example, if absolute independence between the leakage canceled CIRs is desirable, then the M pairs can be used to form M/<NUM> non-overlap groups of two pairs. In this embodiment, M is described as an even number. In other embodiments where M is an odd number, a floor function can be used to avoid inaccurate calculations. If the independence criterion is not required, then the M pairs can be used to form M-<NUM> groups of two pairs. Although depicted herein as M/<NUM> or M-<NUM> groups of two pairs, these embodiments should not be construed as limiting. Other embodiments are possible. The method <NUM> depicts combining leakage canceled CIRs of antenna pairs M for more robust target detection and ranging.

In operation <NUM>, various leakage canceled CIRs are obtained. For example, a leakage canceled CIR <NUM> is obtained in operation 710a, a leakage canceled CIR <NUM> is obtained in operation 710b, and a leakage canceled CIR K is obtained in operation 710n. The leakage canceled CIR K obtained in operation 710n can be understood to represent any number of leakage canceled CIRs from antenna pairs M that are obtained in operation <NUM>. The leakage canceled CIRs <NUM>, <NUM>,. n can be obtained by one or more of the methods described in the description of <FIG>. Each leakage canceled CIR can be obtained from a pair of antenna arrays as described in <FIG>. For example, each of the leakage canceled CIRs can be described as CIRcan[n].

In operation <NUM>, each of the leakage canceled CIRs <NUM>, <NUM>,. n obtained in operation <NUM> are combined by the processor <NUM>. Each of the leakage canceled CIRs <NUM>, <NUM>,. n can be combined in various ways. In some embodiments, the processor <NUM> can combine the leakage canceled CIRs <NUM>, <NUM>,. n by computing the average of the leakage canceled CIRs <NUM>, <NUM>,. The computed average can be in a complex domain or in the power domain, such as the squared amplitude of the complex number. In other embodiments, the processor <NUM> can combine the leakage canceled CIRs <NUM>, <NUM>,. n by performing beamforming on the leakage canceled CIRs <NUM>, <NUM>,. For example, the processor <NUM> can use a maximum ratio combining (MRC) approach to combine the leakage canceled CIRs <NUM>, <NUM>,.

In other embodiments, the processor <NUM> can compute the results of the leakage canceled CIRs <NUM>, <NUM>,. n obtained in operation <NUM> by using a weighted average, the maximum value, or the minimum value. The weighted average can be used to establish a higher weight, i.e. priority, to the leakage canceled CIR of a particular antenna pair. For example, the processor <NUM> can determine a SNR for each antenna pair of the antenna pairs M using Equation <NUM>, <MAT>, and compare the respective SNR values of each of the antenna pairs M to determine a weighted average for the results of operation <NUM>.

In operation <NUM>, the processor <NUM> performs target detection and ranging based on the results of the combined leakage canceled CIRs in operation <NUM>. For example, the processor <NUM> can detect a target based on a peak remaining in the CIR after the leakage has been canceled. The processor <NUM> can further determine the distance of the detected target based on the tap index as shown in the CIR illustrated in <FIG>.

<FIG> illustrates a method of combining multiple leakage canceled CIRs according to various embodiments of the present disclosure. In some embodiments, the processor <NUM> can utilize M antenna pairs rather than a single pair of antennas k and l as described in <FIG>, where M represents the number of antenna pairs. Using M antenna pairs rather than a single pair provides multiple estimates of the CIR after the leakage cancelation.

The number of groupings of two pairs can be selected in various ways. For example, if absolute independence between the leakage cancelled CIRs is desirable, then the M pairs can be used to form M/<NUM> non-overlap groups of two pairs. If the independence criterion is not required, then the M pairs can be used to form M-<NUM> groups of two pairs. Although depicted herein as M/<NUM> or M-<NUM> groups of two pairs, these embodiments should not be construed as limiting. Other embodiments are possible. The method <NUM> depicts performing ranging of each obtained leakage canceled CIR of antenna pairs M before combining the results of the target detection and ranging.

In operation <NUM>, various leakage canceled CIRs are obtained. Operation <NUM> can be performed in the same manner as operation <NUM>. For example, a leakage canceled CIR <NUM> is obtained in operation 810a, a leakage canceled CIR <NUM> is obtained in operation 810b, and a leakage canceled CIR K is obtained in operation 810n. The leakage canceled CIR K obtained in operation 810n can be understood to represent any number of leakage canceled CIRs from antenna pairs M that are obtained in operation <NUM>. The leakage canceled CIRs <NUM>, <NUM>,. n can be obtained by one or more of the methods described in the description of <FIG>. Each leakage canceled CIR can be obtained from a pair of antenna elements as described in <FIG>. For example, each of the leakage canceled CIRs can be described as CIRcan[n].

In operation <NUM>, the processor <NUM> performs target detection and ranging based on each individually obtained leakage canceled CIR. For example, in operation 820a, the processor <NUM> controls to perform target detection and ranging based on the obtained leakage canceled CIR <NUM> in operation 810a. In 820b, the processor <NUM> controls to perform target detection and ranging based on the obtained leakage canceled CIR <NUM> in operation 810b. In 820n, the processor <NUM> controls to perform target detection and ranging based on the obtained leakage canceled CIR K in operation 810n. The target detection and ranging procedure for each of operations 820a, 820b, and 820n can include detecting a target based on a peak remaining in each respective leakage canceled CIR. The processor <NUM> can further determine the distance of the detected target based on the tap index of the detected target in the CIR.

In operation <NUM>, the processor <NUM> combines the results of the target detection and ranging in operation <NUM> from each respective leakage canceled CIR to produce a final detection and estimation output. The processor <NUM> can combine the results in various ways, such as using an average, a weighted average, using the maximum value, and using the minimum value. For example, if three antenna pairs are used at operations 820a, 820b, and 820n and targets are detected at <NUM>, <NUM>, and <NUM> from the electronic device <NUM>, respectively, the processor <NUM> can produce a final output that differs based on the method of combining. If the processor <NUM> averages the results of operation <NUM> to produce the final output, the final output would show a target at <NUM> from the electronic device <NUM>. If the processor <NUM> uses the maximum value, the final output would show a target at <NUM> from the electronic device <NUM>. If the processor <NUM> uses the minimum value, the final output would show a target at <NUM> from the electronic device <NUM>.

In some embodiments, when the processor <NUM> uses weighted averaging to combine the results of operation <NUM>, the processor <NUM> can use the SNR of the detected signals as the weights to establish a higher weight, i.e. priority, to a particular antenna pair of the antenna pairs M. For example, the processor <NUM> can determine a SNR for each antenna pair of the antenna pairs M using Equation <NUM>, <MAT>, and compare the respective SNR values of each of the antenna pairs M to determine a weighted average for the results of operation <NUM>. In the example above, where three antenna pairs are used at operations 820a, 820b, and 820n and targets are detected at <NUM>, <NUM>, and <NUM> from the electronic device <NUM>, respectively, the average is <NUM>. However, using a weighted average where the antenna pair that detects a target at <NUM> has the highest SNR value and is included twice in the weighted average calculation, the weighted average is <NUM>. In this example, the final output of operation <NUM> can show a detected target at <NUM>.

In some embodiments, the processor <NUM> can control to output a binary output. For example, the processor <NUM> can control to output a result indicating that a target is either present or not present in the range or that a target is either present or not present at a particular tap index. In embodiments where the processor <NUM> controls to output a binary result, the processor <NUM> can combine the target detection and ranging results by a majority vote approach. For example, where three antenna pairs are used at operations 820a, 820b, and 820n and targets are detected in operations 820a and 820b but no target is detected in operation 820n, a majority vote approach leads the processor <NUM> to control to output a result indicating a detected target because the two out of three antenna pairs that detected the target constitutes a majority. As another example, the output can be a binary output of whether a target is detected at a particular tap index. In the example where three antenna pairs are used at operations 820a, 820b, and 820n and targets are detected in operations 820a and 820b at the tap index of <NUM> but no target is detected in operation 820n at the tap index of <NUM>, the majority vote approach leads the processor <NUM> to control to output a result indicating a detected target at the tap index of <NUM> because the two out of three antenna pairs that detected the target at the tap index of <NUM> constitutes a majority.

<FIG> illustrates an example of spatial leakage cancelation according to various embodiments of the present disclosure. In particular, <FIG> illustrates a method <NUM> of spatial leakage cancelation using M antenna pairs.

In operation <NUM>, a set of reference pairs, R, are selected from the M antenna pairs. M represents the number of antenna pairs on the electronic device and can be the M antenna pairs described in <FIG> and <FIG>. The set of reference pairs R can be selected based on various criteria. For example, the set of reference pairs R can be selected differently for different delay taps. The set of reference pairs R can be selected from an index that corresponds the set of reference antenna pairs R to a particular delay tap. In some embodiments, the same set of reference pairs can be used for all delay taps that leakage cancelation will be performed on throughout the method <NUM>. For example, one antenna pair of the set of reference pairs R can be the transmission antenna array <NUM> and element <NUM> of the reception antenna array <NUM> and the second antenna pair can be element <NUM> of the transmission antenna array <NUM> and element <NUM> of the reception antenna array <NUM>.

In operation <NUM>, for each of the antenna pairs M on the electronic device, the leakage is canceled using the reference pairs R. In some embodiments, the leakage can be canceled by subtracting the leakage from the CIR of the reference pairs R after scaling by the corresponding leakage scaling factor. An antenna pair can include element <NUM> of the transmission antenna array <NUM> and element <NUM> of the reception antenna array <NUM>, element <NUM> of the transmission antenna array <NUM> and element <NUM> of the reception antenna array <NUM>, and so forth. During operation <NUM> as the leakage from each antenna pair on the electronic device <NUM> is subtracted using the reference pairs R, the reference pairs R will be included in the leakage cancelation. When the antenna pair being subtracted using the reference pairs R is one of the reference pairs, the leakage is subtracted by excluding the reference pair as the reference. The leakage subtraction can be depicted as using R-<NUM> reference pairs. Based on the leakage subtraction for each of the antenna pairs on the electronic device <NUM>, the non-reference antenna pairs have an R leakage subtracted radar signal and the reference antenna pair R have an R-<NUM> leakage subtracted radar signal. The radar signals can be depicted as a CIR as previously described herein.

In operation <NUM>, for each antenna pair, the leakage subtracted CIRs are averaged. For example, when one antenna includes element <NUM> of the transmission antenna array <NUM> and element <NUM> of the reception antenna array <NUM> and the other antenna includes element <NUM> of the transmission antenna array <NUM> and element <NUM> of the reception antenna array <NUM>, the leakage subtracted radar signals of the two antennas are averaged to obtain an averaged leakage canceled, or subtracted, radar signal. In operation <NUM>, the averaged leakage canceled CIRs of the antenna pairs M are combined. For example, the M leakage canceled CIRs can be averaged or combined using a beamforming method. Although operations <NUM> and <NUM> are described herein as being performed in sequence, in some embodiments operations <NUM> and <NUM> can be performed as a single combined step. For example, the processor <NUM> can average each of the R leakage subtracted radar signals and R-<NUM> leakage subtracted radar signals to result in a combined leakage subtracted radar signal. The combined leakage subtracted radar signal is the final output of the leakage cancelation.

In operation <NUM>, the processor <NUM> performs target detection and ranging based on the combined leakage canceled radar signals of the antenna pairs M. The target detection and ranging can include detecting a target based on a peak remaining in the combined leakage canceled CIR. The processor <NUM> can further determine the distance of the detected target based on the tap index of the detected target in the CIR.

<FIG> illustrates an example method of leakage cancelation according to various embodiments of the present disclosure. For example, <FIG> illustrates a method <NUM> of canceling leakage for radar applications as described throughout the present disclosure.

In operation <NUM>, the processor <NUM> identifies a first leakage factor. For example, the processor <NUM> can identify the first leakage factor from leakage factors that are stored in an index in the memory <NUM>.

In operation <NUM>, the processor <NUM> controls the transmit antenna to transmit a first signal. For example, the transmit antenna can be the transmitter <NUM> that transmits a radar signal or radar pulse. The radar signal or pulse can then be reflected off of a target object and then received by a receiving antenna such as the receiver <NUM>. The transmit antenna can be included in an antenna pair that includes the transmit antenna and a receiver antenna.

In operation <NUM>, the processor <NUM> generates a first CIR based on the reflected radar signal that is received by the receiving antenna. The first CIR can be a CIR such as the CIR depicted in <FIG>. The generated CIR is a measure of the reflected signals, or echoes, from one or more potential targets as a function of a distance at the receiving antenna. The y-axis can measure an amplitude of the radar measurement in dB and the x-axis can measure a delay tap index corresponding to distance from the receiving antenna.

In operation <NUM>, the processor <NUM> determines the leakage in the first CIR. The leakage in the first CIR can be determined based on at least the first leakage factor identified in operation <NUM>. More specifically, the processor <NUM> can apply the first leakage factor to the first CIR generated in operation <NUM> to determine leakage in the first CIR.

In operation <NUM>, the processor <NUM> cancels the determined leakage from the first CIR. By canceling the determined leakage from the first CIR, the leakage canceled CIR more accurately depicts the potential target objects in the environment surrounding the electronic device <NUM>.

In some embodiments, the electronic device <NUM> can further include a second antenna pair comprising a second transmitter antenna configured to transmit signals and a second receiver antenna configured to receive signals. The first leakage factor can be a leakage scaling factor for relative leakage cancelation between the first antenna pair and the second antenna pair. In these embodiments, the processor <NUM> can control the second transmitter antenna to transmit a second signal, generate a second CIR based on receipt, by the second receiver antenna, of reflection of the second signal, and, to determine the leakage in the first CIR, determine the leakage in the first CIR based on the leakage scaling factor and the second CIR.

In some embodiments, the processor <NUM> can divide the first CIR by the second CIR to determine the leakage scaling factor. The first CIR can be generated based on a receiver antenna gain of the first antenna pair, a propagation coefficient of the first antenna pair, a transmitter antenna gain of the first antenna pair, and a transmitter and receiver combined filter response of the first antenna pair. The second CIR can be generated based on a receiver antenna gain of the second antenna pair, a propagation coefficient of the second antenna pair, a transmitter antenna gain of the second antenna pair, and a transmitter and receiver combined filter response of the second antenna pair.

In some embodiments, the processor <NUM> can select a set of reference antenna pairs based on more than two antenna pairs being present on the electronic device <NUM>. For each additional antenna pair, the processor <NUM> can cancel leakage of the additional antenna pair from leakage of each reference antenna pair of the set of reference antenna pairs to generate a leakage canceled CIR. The processor <NUM> can then average the leakage canceled CIRs generated from each reference antenna pair of the set of reference antenna pairs.

In some embodiments, to select the set of reference antenna pairs, the processor <NUM> is configured to select the set of reference antenna pairs from an index that corresponds the set of reference antenna pairs to a particular delay tap.

In some embodiments, the memory <NUM> is configured to store the first leakage factor in a template. The processor <NUM> can select the first leakage factor from the template and cancel leakage from an additional CIR that is obtained by an additional antenna pair based on the first leakage factor that is selected from the template.

Claim 1:
An electronic device (<NUM>) comprising:
a first antenna pair (<NUM>) comprising a first transmitter antenna (<NUM>) configured to transmit signals and a first receiver antenna (<NUM>) configured to receive signals;
a memory (<NUM>) configured to store data; and
a processor (<NUM>) operably connected to the first antenna pair, the processor configured to:
identify, from the data stored in the memory, a first leakage factor associated with the first antenna pair;
transmit, via the first transmitter antenna, a first signal;
generate a first channel impulse response, CIR, based on receipt, by the first receiver antenna, of reflection of the first signal;
determine leakage in the first CIR based on at least the identified first leakage factor; and
cancel the determined leakage from the first CIR, the electronic device characterized by:
a second antenna pair comprising a second transmitter antenna configured to transmit signals and a second receiver antenna configured to receive signals, wherein:
the first leakage factor is a measured or precomputed leakage scaling factor for relative leakage cancelation between the first antenna pair and the second antenna pair; and
the processor is further configured to:
transmit, via the second transmitter antenna, a second signal,
generate a second CIR based on receipt, by the second receiver antenna, of reflection of the second signal, and
to determine the leakage in the first CIR, determine the leakage in the first CIR based on the leakage scaling factor and the second CIR.