MIMO channel extenders and related systems and methods

Abstract

To further increase the number of receive and / or transmit antennas that can be supported by a given radar transceiver, multiple-input multiple-output (MIMO) radar systems are equipped with channel extenders. One exemplary radar system includes a radar transceiver for generating a transmit signal and for downconverting at least one receive signal, and a receive extender that couples to a set of multiple receive antennas to obtain a set of multiple input signals, adjustably phase shifts each of the multiple input signals to produce a set of phase-shifted signals, and couples to the radar transceiver to provide at least one receive signal, where the at least one receive signal is a sum of the phase-shifted signals. The exemplary receive extender includes multiple phase shifters, each of which provides an adjustable phase shift to each input signal, and a power combiner that forms the receive signal by combining the outputs of the multiple phase shifters.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims priority to U.S. Non - Provisional Patent Application No. 17 / 160,915, filed on January 28, 2021, the content of which is incorporated herein by reference.

[0002] This application is related to U.S. Patent Application No. 16 / 801,406, filed on February 26, 2020, entitled "MIMO Radar with Receive Antenna Multiplexing" by inventors Danny Elad, Oded Katz, and Tom Heller; U.S. Patent Application No. 16 / 203,149, filed on November 28, 2018, entitled "Reconfigurable MIMO radar" by inventors Danny Elad, Ofer Markish, and Benny Sheinman; and U.S. Patent Application No. 16 / 583,663, filed on September 26, 2019, entitled "Multi - input downconversion mixer" by inventor Benny Sheinman. Each of the above - mentioned applications is hereby incorporated herein by reference in its entirety.

Background Art

[0003] In pursuit of a safer and more convenient transportation option, many car manufacturers are developing self - driving cars, which often require a remarkable number of diverse sensors, including arrays of acoustic sensors and / or electromagnetic sensors, to monitor the distance between the vehicle and any person, pet, vehicle, or obstacle in the vicinity. Although multiple - input multiple - output radar systems are among the envisioned sensing technologies, providing a sufficient number of transmitters and receivers for a fully functional antenna array can be prohibitively costly. The prior art has not been able to propose a completely satisfactory solution to this dilemma.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] U.S. Patent Application No. 16 / 801,406 [Patent Document 2] U.S. Patent Application No. 16 / 203,149 [Patent Document 3] U.S. Patent Application No. 16 / 583,663 [Patent Document 4] U.S. Patent Application No. 16 / 660,370 [Overview of the project] [Means for solving the problem]

[0005] The drawbacks identified above can be addressed, at least in part, by a multi-input, multi-output (MIMO) radar system with channel extenders to further increase the number of receiving and / or transmitting antennas that can be supported by a given radar transceiver. One exemplary radar system includes a radar transceiver for generating a transmit signal and down-converting at least one received signal, and a receiving-side extender which couples with a set of multiple receiving antennas to acquire a set of multiple input signals, adjustably phase-shifts each of the multiple input signals to produce a set of phase-shifted signals, and couples with the radar transceiver to provide at least one received signal, wherein at least one received signal is the sum of the phase-shifted signals.

[0006] An exemplary receiver-side extender includes a set of multiple phase shifters, each providing an adjustable phase shift for each input signal; a power coupler that forms a received signal by combining the outputs of the multiple phase shifters; and an internal memory that stores different sequences of phase shift adjustments for each of the multiple phase shifters. The receiver-side extender may further include an external interface that controls the timing for supplying different sequences from the memory to the multiple phase shifters.

[0007] An exemplary transmitter-side extender includes a power splitter that divides each transmit signal into multiple signal copies, a set of multiple phase shifters, each providing an adjustable phase shift to one of the multiple signal copies, a set of power amplifiers, each deriving one of multiple output signals from a corresponding output of one of the multiple phase shifters, and an internal memory that stores different sequences of phase shift adjustments for each of the multiple phase shifters. The transmitter-side extender may further include an external interface that controls the timing for supplying different sequences from the memory to the multiple phase shifters.

[0008] An exemplary radar detection method includes the steps of generating a chirp waveform; deriving a transmit signal from the chirp waveform; obtaining a set of multiple input signals from a set of multiple receiving antennas; applying an adjustable phase shift to each of the multiple input signals to provide a set of multiple phase-shifted input signals; summing the multiple phase-shifted input signals to form a received signal; combining the received signal with the chirp waveform to obtain a down-converted received signal; deriving a set of digital input signals from the down-converted received signal; and processing the set of digital input signals to determine the reflected energy as a function of interval or travel time.

[0009] The exemplary systems, extenders, and methods may be used individually or in combination with one or more of the following optional features in any preferred combination: 1. The transmit signal includes a sequence of chirps. 2. A receiver extender adjusts the phase shift for multiple input signals once per chirp. 3. The adjusted phase shift provides progressive phase shifts for the multiple input signals for beam steering. 4. The adjusted phase shift provides code division multiplexing for the multiple input signals. 5. A radar transceiver processes at least one down-converted receive signal to obtain a demultiplexed set of digital input signals. 6. The receiver extender adjusts the phase shift for multiple input signals multiple times between each chirp. 7. The adjusted phase shift provides different frequency shifts, different frequency sweep rates, or different code modulations for the multiple input signals. 8. One or more transmitter-side extenders each couple to a radar transceiver to acquire each transmit signal, and each couple to each set of multiple transmit antennas to provide a set of multiple output signals, each of which has an adjustable phase shift. 9. The transmitter-side extender adjusts the phase shift for the multiple output signals once per chirp. 10. The adjusted phase shift provides a progressive phase shift for the multiple output signals for beam steering. 11. The adjusted phase shift provides quadrature code modulation for the multiple output signals. 12. The radar transceiver processes at least one down-converted received signal to acquire a demultiplexed set of digital input signals for each of the transmit antennas. 13. The transmitter-side extender adjusts the phase shift for the multiple output signals multiple times between each chirp. 14. The adjusted phase shift provides different frequency shifts, different frequency sweep rates, or different code modulations for the multiple output signals.15. Each transmitting extender includes a power splitter that divides each transmitted signal into multiple signal copies, a set of multiple phase shifters, each providing an adjustable phase shift to one of the multiple signal copies, and a set of power amplifiers, each deriving one of multiple output signals from a corresponding output of one of the multiple phase shifters. 16. Each receiving extender includes a set of multiple phase shifters, each providing an adjustable phase shift to one of multiple input signals, and a power coupler that forms each received signal by combining the outputs of the multiple phase shifters. 17. Each extender includes internal memory for storing different sequences of phase shift adjustments for each of the multiple input signals. 18. Each extender includes an external interface to control the timing for supplying different sequences from memory to the multiple phase shifters. 19. The radar transceiver supplies a clock signal to each extender to control the timing for supplying sequences of phase shift adjustments from internal memory to the multiple phase shifters. 20. The receiving extender coupled to the radar transceiver that performs the coupling, derivation, and processing steps performs the acquisition, application, and summing steps. [Brief explanation of the drawing]

[0010] [Figure 1] This is an overhead view of an example vehicle equipped with sensors. [Figure 2] This is a block diagram of an example driver assistance system. [Figure 3] This is a schematic diagram of an exemplary multi-input, multiple-output (MIMO) radar system. [Figure 4] This is a block diagram of an exemplary MIMO radar transceiver chip. [Figure 5] This is a block diagram of an exemplary MIMO radar system with an extender chip. [Figure 6] This is a block diagram of an example input extender chip. [Figure 7] This is a block diagram of an exemplary output extender chip. [Figure 8A] This is an illustrative diagram of a data cube representing an obtained set of radar measurements. [Figure 8B] This is an illustrative diagram of a data cube representing a converted set of radar measurements. [Figure 9] This is a data flow diagram for an exemplary radar system. [Figure 10] This is a flowchart illustrating an example of a radar detection method. [Modes for carrying out the invention]

[0011] Technical terms The use of the terms “approximately” or “substantially” means that the parameter has a value that is expected to be close to the stated value. However, as is well known in the art, there are minor variations that may cause the value to be not exactly as stated. Accordingly, expected differences, such as a 10% difference, are reasonable differences that a person skilled in the art would expect and acknowledge as acceptable for the objective or ideal objective described for one or more embodiments of this disclosure. It should also be recognized that the terms “first,” “second,” “next,” “last,” “previous,” “after,” and other similar terms are used solely for explanatory and reference purposes and are not intended to limit any configuration of elements or sequences of operation for the various embodiments of this disclosure. Furthermore, the terms “coupled,” “connected,” and others are not intended to limit such interaction and communication of signals between two or more devices, systems, components, etc., to direct interactions, and indirect coupling and connecting may also occur.

[0012] It should be understood that the following description and the accompanying drawings are provided for illustrative purposes and are not provided to limit the present disclosure. That is, they provide a basis for those skilled in the art to understand all modifications, equivalents, and alternative forms that fall within the scope of the claims. More specifically, although a vehicle is used as an exemplary usage context in the following description, the disclosed principles and technologies are also applicable to other usage contexts such as traffic monitoring, parking space occupancy detection, and distance measurement.

[0013] FIG. 1 shows an exemplary vehicle 102 equipped with a radar antenna array, which includes an antenna array 104 for short-range sensing (e.g., for parking assistance) and an antenna array 108 for long-range sensing (e.g., for adaptive cruise control and collision warning), each of which may be placed on the back side of the front bumper cover. An antenna array 110 for short-range sensing (e.g., for reverse assistance) and an antenna array 112 for medium-range sensing (e.g., for rear collision warning) may be placed on the back side of the rear bumper cover. An antenna array 114 for short-range sensing (e.g., for blind spot monitoring and side obstacle detection) may be placed on the back side of the vehicle fender. Each antenna array can perform multiple-input multiple-output (MIMO) radar sensing. The types, numbers, and configurations of sensors in the sensor arrangement for a vehicle having driver assistance and autonomous driving features are diverse. The vehicle can be steered while avoiding other vehicles and obstacles using a sensor arrangement for detecting and measuring the distance / direction to objects in various detection zones.

[0014] Figure 2 shows an electronic control unit (ECU) 202 of a vehicle (e.g., 102) as the center of a star topology, coupled to various radar sensors 204-206. Naturally, other sensor bus topologies, including series, parallel, and hierarchical (tree) topologies, are also preferred and intended for use according to the principles disclosed herein. Each radar sensor includes a radio frequency (RF) front end, which is coupled to one of the transmitting and receiving antenna arrays 104A-114D to transmit and receive electromagnetic waves and determine the spatial relationship between the vehicle and its surroundings. To provide automated parking, assisted parking, lane following, lane change assistance, obstacle and blind spot detection, automatic braking, autonomous driving, and other desirable features, the ECU 202 may be further coupled to a set of actuators, such as a turn signal actuator 208, a steering actuator 210, a throttle actuator 212, and a braking actuator 214. The ECU202 can be further coupled to the user interaction interface 216 to accept user input and provide displays of various measurements and system statuses.

[0015] To collect the necessary measurement values, the ECU can use a MIMO radar sensor. The MIMO radar sensor operates by emitting electromagnetic waves that move outward from a set of transmit antennas before being reflected back to a set of receive antennas. A reflector can be any object that moderately reflects in the path of the emitted electromagnetic waves. By measuring the travel time of the electromagnetic waves from the transmit antenna to the reflector and back to the receive antenna, the radar sensor can determine the distance to the reflector. By using multiple transmit or receive antennas, or by obtaining multiple measurement values at different positions, the radar sensor can determine the direction to the reflector and thus track the location of the reflector relative to the vehicle. With more advanced processing, multiple reflectors can be tracked. At least some radar sensors use array processing to "scan" the directional beam of the electromagnetic wave and construct an image of the surrounding situation of the vehicle. Both pulsed and continuous wave implementations of the radar system can be implemented, but for accuracy, a frequency-modulated continuous wave radar system is generally preferred.

[0016] Figure 3 shows an exemplary MIMO radar antenna arrangement where M transmitters are coupled to M transmit antennas to simultaneously send M transmit signals. The M signals may be variously reflected from one or more targets and received by N receive antennas coupled to N receivers. Each receiver can obtain a measurement value in response to each of the M transmit signals, whereby the system can simultaneously acquire N*M spatially diverse measurement values. Each such measurement value can indicate the distance to multiple targets and, when combined in various ways, can further indicate the direction and velocity of each target.

[0017] Figure 4 shows a block diagram of an exemplary transceiver, or "RF front-end" chip 402, configured for use in a MIMO radar system. Chip 402 includes a chirp generator 404, which converts a local oscillator signal into a frequency-modulated continuous wave (FMCW) signal, such as a signal with a series of linear-swept frequency chirps. A power splitter 406 separates a portion of the FMCW signal power and supplies a copy of the FMCW signal to a down-conversion mixer 407. The remaining FMCW signal goes to a set of phase shifters 408, which a controller 409 uses to independently phase-shift the FMCW signal for each of the RF outputs.

[0018] Phase shifting can be used in various ways, for example, to enable virtual beam steering by providing coherent beam steering or channel isolation. Channel isolation can be provided using quadrature coded phase modulation with different coding patterns for each channel. Alternatively, phase shifting can provide channel isolation through the use of different frequency shifts, different frequency sweep rates, or spreading codes (e.g., Barker codes, maximum-length sequence codes). Phase modulation may be 1 bit (bipolar phase-shift keying), 2 bits (quadrature phase-shift keying), or higher order (N bits). Power amplifier 410 receives the phase-shifted FMCW signal and drives contacts to provide the transmit signals (Tx0 to Tx2). The illustrated transceiver provides three transmit signals, but this number can vary. The transmit signals may be provided to the transmit antenna, or to a transmit-side extender chip to increase the number of transmit antennas driven from the transceiver chip 402, as will be discussed further below.

[0019] The transceiver chip 402 further includes contacts for acquiring four received signals (Rx0 to Rx3) from the receiving antenna, or from the receiving-side extender chip to increase the number of receiving antennas supported by the transceiver chip, as will be discussed further below. The down-conversion mixer 407 multiplies the received signal by a copy of the FMCW signal and converts the received signal to an approximate baseband frequency that is passed through the low-pass filter 412. The gain-controlled amplifier 414 adaptively adjusts the signal amplitude to optimize the use of the dynamic range of the analog-to-digital converter (ADC) 416. The ADC 416 digitizes the received signal for processing by the controller 409. The controller 409 can take the form of a programmable digital signal processor with high-speed memory (SRAM) and a serial peripheral interface (SPI) to enable communication with other chips in the system.

[0020] At signal frequencies intended for automotive radar (e.g., 80 GHz), it is preferable to keep antenna feed lines short to minimize attenuation and electromagnetic interference. However, due to the relationship between the physical size of the transceiver chip and the pitch of the antenna array, it becomes difficult to keep the antenna feed lines at an acceptable length when the array size exceeds approximately 7 or 8 antennas. Using additional chips (such as extender chips) each supporting a small number of antennas (e.g., 3 or 4) allows the chips to be positioned near the corresponding antennas to minimize feed line length, and the use of amplifiers and additional shielding can provide some protection to any inter-chip communication.

[0021] Accordingly, Figure 5 shows a block diagram of a MIMO radar system using extender chips to increase the number of transmitter and receiver antennas supported by a given transceiver chip 402. Each of the four receive signal contacts is coupled to each of the receiving extender chips 502A-502D. Each receiving extender chip receives input signals from the corresponding set of receiving antennas 504A-504D, provides an adjustable phase shift to the input signals, and combines the phase-shifted signals to provide the received signal to the transceiver chip 402. In the illustrated system, each receiving extender chip combines four input signals to form a received signal, but the number of input signals may vary.

[0022] Each of the three transmit signal contacts of the transceiver chip 402 is coupled to each of the transmitter extender chips 506A-506C. Each transmitter extender chip uses a controllable phase shifter to convert the transmit signal into multiple output signals to the corresponding set of transmitter antennas 508A-508C in order to phase-shift or frequency-shift each of the transmit signals by a desired amount, or to modulate each output signal with a desired channel code. In the illustrated system, each transmitter extender chip converts the transmit signal into three output signals, but the number of output signals may vary.

[0023] The transceiver chip 402 is coupled to each of the extender chips by digital control signal lines 510, which may include an SPI bus. The signal lines 510 allow the transceiver chip to program the extender chip with a desired phase shift and / or channel code, and allow the transceiver chip to control the timing of any transitions in the phase shift.

[0024] Although not shown here, extender chips may be used in a hierarchical manner. For example, instead of coupling the input of receiver extender chip 502A to antenna 504A, each of those inputs may be coupled to a separate receiver extender chip, increasing the number of antennas multiplexed on the transceiver's Rx0 channel from 4 to 16. This can be repeated for each of receiver extender chips 502B to 502D to increase the total number of receiver antennas from 16 to 64. Transmitter extender chips 506A to 506C can be similarly coupled to a second level of the transmitter extender chip, increasing the number of supported transmitter antennas from 9 to 27. Additional hierarchical layers can be added, for example, until limited by the processing capacity of transceiver chip 402.

[0025] Figure 6 shows an exemplary receiver-side extender chip 502 having three input contacts (RF_IN1 to RF_IN3) for the received antenna signal. Each input signal is coupled to one of several controllable phase shifters 602, and a power coupler 604 sums the phase shifter outputs to provide the combined received signal to a low-noise amplifier (LNA) 606. The LNA 606 drives the combined received signal to downstream chips such as transceiver 402 via an output contact RF_OUT. The receiver-side extender chip 502 includes an on-chip controller 610 for controlling the phase shifters 602 using each sequence of adjustable phase shifts from on-chip memory 608. The timing of the phase shift adjustments may vary, but at least some implementations apply a fixed phase shift to each chirp and switch to the next phase shift for the next chirp. This approach avoids any bandwidth expansion of the combined received signal but requires the use of multi-chirp measurements to isolate contributions from various antennas that could potentially affect the time resolution or velocity resolution of the measurement. Alternatively, phase shift adjustments can be performed multiple times between each chirp to provide different frequency shifts, different frequency sweep rates, or code modulation, spreading the input signal energy across a wider spectrum. Multi-chirp measurements can be avoided, although the transceiver may need to increase the digitization rate. The timing of the phase shift adjustments may be coordinated by the transceiver 402 to all extender chips via the SPI bus 612 or via another shared clock signal line.

[0026] All automotive electronics preferably include circuits for verifying proper operation. To this end, the receiving extender chip 502 may include a supply voltage monitor 614 for detecting undervoltages and overvoltages, and further may include a test input (RF_INJECT) through which a test signal can be coupled to the antenna input contacts. When the test signal is applied, the transceiver 402 verifies that the test signal can be detected from each of the antenna inputs.

[0027] Figure 7 shows an exemplary transmitter-side extender chip 506 having an input contact (RF_IN) for receiving the transmit signal. A power splitter divides the transmit signal into multiple copies, one for each of several controllable phase shifters 704. The output of each phase shifter 704 is coupled to each transmit signal contact by each power amplifier 706, which is suitable for connection to a transmit antenna. The transmitter-side extender chip 506 includes an on-chip controller 710 for controlling the phase shifters 704 using each sequence of phase shift adjustments from on-chip memory 708. Similar to the receiver-side extender, the timing of the phase shift adjustments may be coordinated by the transceiver 402 via an SPI bus 712 or another shared clock signal line. To avoid bandwidth expansion, the transmitter-side code symbols (phase shifts) may be held fixed for each chirp and switched exclusively between chirps. Alternatively, phase shifters may be used to provide the output signal with different frequency shifts, different frequency sweep rates, or different spreading codes.

[0028] Similar to the receiving extender, the transmitting extender may include circuitry for verifying proper operation. For example, a supply voltage monitor 714 can detect any undervoltage or overvoltage that may potentially affect the operation of the component. For proper operation, a phase difference detector 716 may be included to compare the phases between adjacent phase shifters 704, and a power detector 718 may be included to monitor the output of the power amplifier 706. The operation of the phase shifter can be periodically verified by incrementing each of the possible combinations of phase shifter setpoints and verifying that the phase difference detector 716 measures the expected phase difference, as described in the jointly owned U.S. Patent Application No. 16 / 660,370 filed October 22, 2019, by the inventors Tom Heller, Oded Katz, Danny Elad, and Benny Sheinman, entitled “Radar Array Phase Shifter Verification”. The extender chip can notify the transceiver of any detected faults via the SPI bus.

[0029] Figure 8A shows an exemplary data cube representing some of the digital signal measurements that may be collected by the transceiver 402. Typically, each chirp would be considered a measurement cycle, but with the use of code multiplexing, a measurement cycle may span multiple chirps. During a measurement cycle, the front-end digitizes and decouples the down-converted received signal from a selected receiving antenna, thereby providing a time sequence of digitized received signal samples. Due to chirp modulation, the signal energy reflected by the target reaches the receiving antenna with a frequency offset that depends on the round-trip travel time (and thus the distance to the target). A Fast Fourier Transform (FFT) of the time sequence collected in a given cycle will decouple the energy associated with each frequency offset, yielding a function of reflected energy versus target distance. This operation, which may be referred to herein as the “distance FFT”, may be performed for each transmit-receive antenna pair in each measurement cycle. The distance FFT yields a peak for each target with a given distance.

[0030] The movement of the target relative to the antenna array adds a Doppler shift to the reflected signal energy, which is essentially proportional to the relative velocity. This is usually small compared to the frequency offset due to distance, but is nevertheless observable as a change in the phase of the associated frequency coefficient in subsequent measurement cycles (recall that FFT coefficients are complex values ​​with both amplitude and phase). Applying an FFT to the corresponding frequency coefficients in a sequence of measurement cycles decouples the energy associated with each relative velocity, yielding a function of reflected energy versus target velocity. This operation, which may be referred to herein as “velocity FFT”, may be performed for each distance and for each pair of tx-rx antennas. The resulting two-dimensional data array has a “peak” for each target with a given distance and relative velocity.

[0031] The reflected energy from a given target reaches each receiving antenna in an antenna array with a phase that depends on the direction of arrival of the reflected energy (also known as the "angle of entry"). Applying an FFT to the corresponding frequency coefficients associated with a sequence of evenly spaced antennas decouples the energy associated with each angle of entry, yielding a function of reflected energy versus angle of entry ("AoA"). This operation, which may be referred to herein as "AoA FFT," may be performed for distance and velocity using a given transmitting antenna.

[0032] Thus, digitized signal measurements placed in a measurement data cube having three dimensions representing a function of time, measurement cycle, and antenna position (as shown in Figure 8A) can be converted into a target data cube having three dimensions representing a function of distance, velocity, and AoA (as shown in Figure 8B). Since these operations (channel separation, distance FFT, velocity FFT, and AoA FFT) are linear, they can be performed in any order. Furthermore, the FFT operations are independent (meaning, for example, a distance FFT for a given antenna and cycle is independent of distance FFTs for other antennas and other cycles, and a velocity FFT for a given distance and antenna is independent of velocity FFTs for other distances and antennas), allowing the FFT processing to be parallelized if desired.

[0033] Another desirable processing operation is the separation of signal energy from noise energy. Any suitable noise suppression or target detection technique may be used. One common technique (with many variations) is the constant false alarm rate (CFAR) detection technique. CFAR detection uses detection threshold adaptation based on measured energy values ​​in a sliding window near or around the measured value being evaluated (also known as the "cell under test"). The original technique and its variations propose various trade-offs between performance and computational complexity by using different statistical approaches to deriving the detection threshold from the measured values ​​within the sliding window. CFAR detection is a nonlinear technique because measured values ​​below the threshold are zeroed out or ignored; however, its position in the processing sequence can nevertheless be corrected because zeroing out the frequency coefficient generally does not prevent the subsequent FFT from utilizing the relevant phase / frequency information of the energy peak representing the target.

[0034] Figure 9 shows an exemplary data flow 900, which may be implemented by the transceiver chip 402 or divided between the transceiver chip and the ECU. Digitized received signal x kOnce the signal is acquired, the controller 409 demultiplexes the received antenna signal using the phase shift adjustment applied in the transceiver, any transmit-side extender, and / or any receive-side extender, to decouple the contribution from each transmit antenna, thereby isolating the channels corresponding to each transmit-receive antenna pair (this channel isolation is not necessary if the phase shift is used for beam steering). Essentially, once the signal is acquired, the controller 409 can perform a distance FFT 902 for each channel and store the resulting frequency coefficients as distance data in the frame buffer 904. The frame buffer 904 accumulates distance data from multiple measurement cycles, then allows the controller 409 to perform a velocity FFT 906 to generate target distance and velocity data for each channel, as discussed earlier.

[0035] The CFAR detector 908 operates on the target distance and velocity data to remove noise energy below an adaptive threshold. The CFAR detector 908 can zero out values ​​below the threshold, leaving only values ​​above the threshold as representing the distance and velocity of the potential target (radar energy reflector). In certain intended variations, the CFAR detection process compresses the data volume by omitting at least some of the values ​​below the threshold, and possibly by employing more advanced data compression techniques, thereby reducing buffer size and / or bus bandwidth requirements. The controller 409 or ECU 202 can further perform an AoA FFT 910 to determine the relative orientation associated with the potential target and analyze any peaks in the data volume to detect and track the target's relative position and velocity to the vehicle (912).

[0036] Figure 10 is a flowchart of an exemplary radar detection method that can be implemented by a MIMO radar system with an extender. The method begins in block 1002, using a chirp generator 404 to generate a chirp signal with intervals, where the signal frequency increases linearly from a start frequency to an end frequency. The chirp signal may be an up-chirp signal, a down-chirp signal, or even a triangular up-and-down chirp signal. The chirp signal is divided into multiple transmit signals, and in block 1004, the transceiver 402 optionally applies adjustable phase shifts to the different transmit signals to provide, for example, beamforming, quadrature code modulation, and / or frequency shifting, and in block 1006, the system further divides each of the transmit signals into multiple output signals using a transmit-side extender chip, and the output signals may be further phase-shifted in different sequences of phase-shift adjustments before being fed to different transmit antennas.

[0037] In block 1008, to provide beam steering, quadrature coding, or frequency shifting, input signals from various receiving antennas are optionally phase-shifted, and the phase-shifted signals are combined to form a received signal for digitization. In block 1010, controller 409 optionally uses a phase-shift sequence to separate signals from each transmit-receive antenna pair. In block 1012, controller 409 and / or ECU 202 convert the signals to extract energy peaks indicating a target, which can then be used in block 1014 to detect and track a target relative to a vehicle. In block 1016, ECU 202 can evaluate whether the target requires any action, such as alerting the driver to avoid a collision or automatically braking and steering, and if so, can act accordingly.

[0038] Although the operations in Figure 10 are described sequentially for illustrative purposes, in practice, various operations may be implemented simultaneously or in a pipelined manner. Furthermore, in some implementations, the operations may be performed in a different order or asynchronously.

[0039] The use of a receiver-side extender allows a transceiver to support additional receiver antennas by combining input signals from multiple receiver antennas. Conversely, the use of a transmitter-side extender allows a transceiver to support additional transmit antennas by splitting the transmit signal. A phase modulator allows a transceiver to distinguish the contributions of individual transmit and receive antennas. The phase modulator may be implemented as a bipolar phase-shift keying (BPSK) modulator, a quadrature phase-shift keying (QPSK) modulator, or a higher-order phase-shift keying modulator.

[0040] Once the above disclosure is fully recognized, numerous other modifications, equivalents, and alternatives will become apparent to those skilled in the art. The following claims are intended to be construed to encompass all such modifications, equivalents, and alternatives, where applicable. [Explanation of symbols]

[0041] 102 vehicles 104 Antenna Array 108 Antenna Array 110 Antenna Array 112 Antenna Array 114 Antenna Array 202 Electronic Control Unit 204 Radar Sensor 205 Radar Sensor 206 Radar Sensors 208 Turn Signal Actuator 210 Steering Actuator 212 Throttle Actuator 214 Braking Actuator 216 User Interaction Interfaces 402 Transceiver Chip, RF Front-End Chip 404 Chirp Generator 406 Power Splitter 407 Down Conversion Mixer 408 Phase Shifter 409 Controller 410 Power Amplifier 412 Low-pass filter 414 Gain-controlled amplifier 416 Analog-to-Digital Converter 502A Receiver Extender Chip 502B Receiver Extender Chip 502C Receiver Extender Chip 502D Receiver Extender Chip 504A Receiving Antenna 504B Receiving Antenna 504C Receiving Antenna 504D Receiving Antenna 506A Transmitter Extender Chip 506B Transmitter Extender Chip 506C Transmitter Extender Chip 508A Transmitting Antenna 508B Transmitting Antenna 508C Transmitting Antenna 510 Digital control signal line 602 Phase Shifter 604 Power combiner 606 Low-noise amplifier 608 on-chip memory 610 On-Chip Controller 612 SPI bus 614 Supply Voltage Monitor 704 Phase Shifter 706 Power Amplifier 708 On-chip memory 710 On-Chip Controller 712 SPI bus 714 Supply Voltage Monitor 716 Phase difference detector 718 Power detector 902 Distance FFT 904 Framebuffer 906 Velocity FFT 908 CFAR detector 910 AoA FFT

Claims

1. A radar transceiver for generating a transmit signal and for down-converting at least one receive signal, A receiving-side extender coupled to a set of multiple receiving antennas to acquire a set of multiple input signals, adjustably phase-shifting each of the multiple input signals to produce a set of phase-shifted signals, and coupled to the radar transceiver to provide the at least one received signal, wherein the at least one received signal is the sum of the phase-shifted signals. Includes, The radar transceiver is mounted on a first chip, the receiving extender is mounted on a second chip physically separated from the first chip, and the number of receiving antennas supported by the radar transceiver via the receiving extender is greater than the number of receiving antennas that the radar transceiver can support on its own. The radar transceiver is configured to process the at least one received signal to obtain a set of demultiplexed signals corresponding to each of the plurality of receiving antennas. The receiving extender includes an internal memory for storing a phase shift adjustment sequence for each of the plurality of input signals and for autonomously performing phase shifts. Radar system.

2. The radar system according to claim 1, wherein the transmitted signal includes a sequence of chirps, and the receiving extender adjusts the phase shift for the plurality of input signals once for each chirp.

3. The radar system according to claim 2, wherein the adjusted phase shift provides a progressive phase shift to the plurality of input signals for beam steering.

4. The radar system according to claim 2, wherein the adjusted phase shift provides code division multiplexing of the plurality of input signals, and the radar transceiver processes the down-converted at least one received signal to obtain a demultiplexed set of digital input signals.

5. The radar system according to claim 1, wherein the transmitted signal includes a sequence of chirps, and the receiving extender adjusts the phase shift of the plurality of input signals multiple times between each chirp.

6. The radar system according to claim 5, wherein the adjusted phase shift provides the plurality of input signals with different frequency shifts, different frequency sweep rates, or different code modulations, and the radar transceiver processes the down-converted at least one received signal to obtain a demultiplexed set of digital input signals.

7. The radar system according to claim 1, further comprising one or more transmitter-side extenders, each coupled to the radar transceiver to acquire each transmit signal, and each coupled to each set of a plurality of transmit antennas to provide a set of a plurality of output signals, wherein each of the plurality of output signals has an adjustable phase shift.

8. The radar system according to claim 7, wherein the transmitted signal includes a sequence of chirps, and the transmitting extender adjusts the phase shift for the plurality of output signals once for each chirp.

9. The radar system according to claim 8, wherein the adjusted phase shift provides a progressive phase shift to the plurality of output signals for beam steering.

10. The radar system according to claim 8, wherein the adjusted phase shift provides quadrature code modulation to the plurality of output signals, and the radar transceiver processes the down-converted at least one received signal to obtain a demultiplexed set of digital input signals for each of the transmitting antennas.

11. The radar system according to claim 7, wherein the transmitted signal includes a sequence of chirps, and the transmitting extender adjusts the phase shift for the plurality of output signals multiple times between each chirp.

12. The radar system according to claim 11, wherein the adjusted phase shift provides the plurality of output signals with different frequency shifts, different frequency sweep rates, or different code modulations, and the radar transceiver processes the down-converted at least one received signal to obtain a demultiplexed set of digital input signals for each of the transmitting antennas.

13. Each transmitting extender, A power splitter that divides each of the aforementioned transmission signals into multiple signal copies, A set of multiple phase shifters, each providing an adjustable phase shift to one of the aforementioned multiple signal copies, A set of power amplifiers, each of which derives one of the multiple output signals from a corresponding output of one of the multiple phase shifters, and The radar system according to claim 7, including the following:

14. A second receiving-side extender that couples to a second set of multiple receiving antennas to acquire a second set of multiple input signals and couples to the radar transceiver to provide a second received signal. It further includes, Each of the aforementioned receiving extenders, A set of multiple phase shifters, each providing an adjustable phase shift to one of the aforementioned multiple input signals, A power coupler that forms each received signal by coupling the outputs of the plurality of phase shifters, An internal memory for storing a phase shift adjustment sequence for each of the aforementioned plurality of input signals The radar system according to claim 1, including the following:

15. The radar system according to claim 14, wherein the radar transceiver supplies a clock signal to each of the receiving extenders to control the timing for supplying the sequence of phase shift adjustments from the internal memory to the plurality of phase shifters.

16. Steps to generate a chirp waveform, The steps include: deriving a transmission signal from the chirp waveform; The steps include obtaining a set of multiple input signals from a set of multiple receiving antennas, To provide multiple phase-shifted input signals, the steps include: applying an adjustable phase shift to each of the multiple input signals based on different sequences of phase shift adjustments for each of the multiple phase shifters stored in internal memory; The steps include summing the plurality of phase-shifted input signals in order to form a received signal, To obtain a down-converted received signal, the steps include: combining the received signal with the chirp waveform; The steps include: deriving a set of digital input signals from the down-converted received signal; The steps include: determining the reflected energy as a function of interval or travel time, processing the set of digital input signals; Includes, The steps of generating, deriving the transmission signal, deriving the set of digital input signals, and processing are performed by a radar transceiver mounted on a first chip, the steps of acquiring, applying, and summing are performed by a receiver-side extender mounted on a second chip physically separated from the first chip, and the number of receiving antennas supported by the radar transceiver via the receiver-side extender is greater than the number of receiving antennas that the radar transceiver can support on its own. A radar detection method in which the radar transceiver is configured to process the received signal to obtain a set of demultiplexed signals corresponding to each of the plurality of receiving antennas.

17. The radar detection method according to claim 16, wherein the acquiring step, the applying step, and the summing step are performed by a receiving-side extender coupled to a radar transceiver that performs the coupling step, the derivation step, and the processing step.

18. The radar detection method according to claim 17, further comprising the step of using a transmitter-side extender for providing a set of multiple output signals to a set of multiple transmitting antennas, each of which is an adjustablely phase-shifted version of the transmitting signal.

19. The radar detection method according to claim 18, wherein the derivation step yields a corresponding set of digital input signals for each of the transmitting antennas.

20. A receiver-side extender, mounted on a second chip physically separated from the first chip, for use in combination with a radar transceiver mounted on a first chip, A set of multiple phase shifters, each providing an adjustable phase shift for each input signal, A power coupler that forms a received signal by coupling the outputs of the plurality of phase shifters, An internal memory that stores different phase shift adjustment sequences for each of the aforementioned plurality of phase shifters Includes, The receiving extender is, Multiple input signals are acquired from a set of multiple receiving antennas, and each of the multiple input signals is phase-shifted according to a phase-shift adjustment sequence stored in the internal memory, thereby providing at least one received signal to the radar transceiver. Multiplexing via at least one of the received signals enables the radar transceiver to support more receiving antennas than it can support on its own. It is configured in such a way. Receiver extender.

21. The receiving extender according to claim 20, further comprising an external interface for controlling the timing of supplying the different sequences from the internal memory to the plurality of phase shifters.

22. A transmitter-side extender, mounted on a second chip physically separated from the first chip, for use in combination with a radar transceiver mounted on a first chip, A power splitter that divides each transmitted signal into multiple signal copies, A set of multiple phase shifters, each providing an adjustable phase shift to one of the aforementioned multiple signal copies, A set of power amplifiers, each of which derives one of a plurality of output signals from a corresponding output of one of the plurality of phase shifters, An internal memory that stores different phase shift adjustment sequences for each of the aforementioned plurality of phase shifters Includes, The aforementioned transmitting extender is According to the phase shift adjustment sequence stored in the internal memory, a plurality of output signals, each having an adjustable phase shift, are derived from the transmitted signal from the radar transceiver. Through the derivation of the multiple output signals, the radar transceiver can support more transmitting antennas than it can support on its own. It is configured in such a way. Transmitter extender.

23. The transmitter-side extender according to claim 22, further comprising an external interface for controlling the timing of supplying the different sequences from the internal memory to the plurality of phase shifters.

Images