Patent Description:
In high-resolution radar such as in automotive applications, a number of hyper-voxels of a <NUM>-D sphere is large, while a measurement time is limited due to the required frame rate. Phased array beamforming with analog beamformer has limited frame rate due to a number of simultaneous beams that can be generated and a number of signals that can be transmitted simultaneously. <NPL> discloses information relating to Random Access Channel preamble design.

In the present disclosure, multi-stream transmission and reception schemes are provided for high-resolution radar. The present disclosure provides sub-band coded OFDM for high-resolution radar. The present disclosure allows a transmission and reception of the signal in multiple beams in beamforming mode, or multiple antennas in MIMO mode, without interference between the beams or antennas. The provided embodiments reduce the acquisition time by MxN fold, where M is a number of transmit beams (or MIMO layers) and N is a number of receive beams (or MIMO layers).

In one embodiment, a system is provided. The system comprises: a set of antennas including a set of transmit antennas and a set of receive antennas; a digital beamformer; a processor operably connected to the set of antennas and the digital beamformer, the processor configured to: identify a set of orthogonal multiple-input-multiple-output (MIMO) signals, generate a first set of beams via the digital beamformer, and map the set of orthogonal MIMO signals into each of the generated set of beams. The system further comprises a transceiver operably connected to the processor, the transceiver configured to: transmit, to a target scene via the set of transmit antenna of the set of antennas, a first signal based on the first set of beams; illuminate, using the set of orthogonal MIMO signals, the target scene with a same transmit beam of the first set of beams; and receive, via the set of receive antennas of the set of antennas, a second signal based on a second set of beams that is reflected or backscattered from the target scene. The processor is further configured to: identify, based on a targeted range, an operation mode comprising a MIMO operation mode, a hybrid of MIMO and beamforming operation mode, or a beamforming operation mode; transmit, the first signal based on the identified operation mode; and receive, the second signal based on the identified operation mode. The processor is further configured to apply the MIMO operation mode and the beamforming operation mode at alternating dwell times for simultaneous short-range and long-range operation.

In another embodiment, a method for a system is provided. The method comprises: identifying a set of orthogonal multiple-input-multiple-output (MIMO) signals; generating a first set of beams; mapping the set of orthogonal MIMO signals into each of the generated set of beams; transmitting, to a target scene, a first signal based on the first set of beams; illuminate, using the set of orthogonal MIMO signals, the target scene with a same transmit beam of the first set of beams; and receiving a second signal based on a second set of beams that is reflected or backscattered from the target scene. The method further comprises: identifying, based on a targeted range, an operation mode comprising a MIMO operation mode, a hybrid of MIMO and beamforming operation mode, or a beamforming operation mode; transmitting, the first signal based on the identified operation mode; and receiving, the second signal based on the identified operation mode. The method further comprises applying the MIMO operation mode and the beamforming operation mode at alternating dwell times for simultaneous short-range and long-range operation.

In yet another embodiment, a non-transitory computer-readable medium is provided. The non-transitory computer-readable medium comprises program code, that when executed by at least one processor, causes a system to: identify a set of orthogonal multiple-input-multiple-output (MIMO) signals; generate a first set of beams; map the set of orthogonal MIMO signals into each of the generated set of beams; transmit, to a target scene, a first signal based on the first set of beams; illuminate, using the set of orthogonal MIMO signals, the target scene with a same transmit beam of the first set of beams; and receive a second signal based on a second set of beams that is reflected or backscattered from the target scene. The program code, when executed by the at least one processor, further causes the system to identify, based on a targeted range, an operation mode comprising a MIMO operation mode, a hybrid of MIMO and beamforming operation mode, or a beamforming operation mode; transmit, the first signal based on the identified operation mode; and receive, the second signal based on the identified operation mode. The program code, when executed by the at least one processor, further causes the system to apply the MIMO operation mode and the beamforming operation mode at alternating dwell times for simultaneous short-range and long-range operation.

For a more complete understanding of this disclosure, reference is made to the following description, taken in conjunction with the accompanying drawings, in which:.

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

<FIG> describe various embodiments implemented in wireless communications systems and with the use of orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication techniques. The descriptions of <FIG> are not meant to imply physical or architectural limitations to the manner in which different embodiments may be implemented. Different embodiments of the present disclosure may be implemented in any suitably arranged communications system.

As shown in <FIG>, the wireless network includes a gNB <NUM>, a gNB <NUM>, and a gNB <NUM>. The gNB <NUM> communicates with the gNB <NUM> and the gNB <NUM>. The gNB <NUM> also communicates with at least one network <NUM>, such as the Internet, a proprietary Internet Protocol (IP) network, or other data network. In one embodiment, such gNBs <NUM>-<NUM> may be implemented as a system including a radar system supporting multi-stream MIMO and/or beamforming radar.

The gNB <NUM> provides wireless broadband access to the network <NUM> for a first plurality of user equipments (UEs) within a coverage area <NUM> of the gNB <NUM>. The first plurality of UEs includes a UE <NUM>, which may be located in a small business (SB); a UE <NUM>, which may be located in an enterprise (E); a UE <NUM>, which may be located in a WiFi hotspot (HS); a UE <NUM>, which may be located in a first residence (R); a UE <NUM>, which may be located in a second residence (R); and a UE <NUM>, which may be a mobile device (M), such as a cell phone, a wireless laptop, a wireless PDA, or the like. The gNB <NUM> provides wireless broadband access to the network <NUM> for a second plurality of UEs within a coverage area <NUM> of the gNB <NUM>. The second plurality of UEs includes the UE <NUM> and the UE <NUM>. In some embodiments, one or more of the gNBs <NUM>-<NUM> may communicate with each other and with the UEs <NUM>-<NUM> using <NUM>, LTE, LTE-A, WiMAX, WiFi, or other wireless communication techniques. In one embodiment, such UEs <NUM>-<NUM> may be implemented as a system including a radar system supporting multi-stream MIMO and/or beamforming radar.

Depending on the network type, the term "base station" or "BS" can refer to any component (or collection of components) configured to provide wireless access to a network, such as transmit point.

(TP), transmit-receive point (TRP), an enhanced base station (eNodeB or eNB), a <NUM> base station (gNB), a macrocell, a femtocell, a WiFi access point (AP), or other wirelessly enabled devices. Base stations may provide wireless access in accordance with one or more wireless communication protocols, e.g., <NUM> 3GPP new radio interface/access (NR), long term evolution (LTE), LTE advanced (LTE-A), high speed packet access (HSPA), Wi-Fi <NUM>1a/b/g/n/ac, etc. For the sake of convenience, the terms "BS" and "TRP" are used interchangeably in this patent document to refer to network infrastructure components that provide wireless access to remote terminals. Also, depending on the network type, the term "user equipment" or "UE" can refer to any component such as "mobile station," "subscriber station," "remote terminal," "wireless terminal," "receive point," or "user device. " For the sake of convenience, the terms "user equipment" and "UE" are used in this patent document to refer to remote wireless equipment that wirelessly accesses a BS, whether the UE is a mobile device (such as a mobile telephone or smartphone) or is normally considered a stationary device (such as a desktop computer or vending machine).

As described in more detail below, one or more of the UEs <NUM>-<NUM> include circuitry, programing, or a combination thereof, for reception reliability for data and control information in an advanced wireless communication system. In certain embodiments, and one or more of the gNBs <NUM>-<NUM> includes circuitry, programing, or a combination thereof, for efficient synthetic aperture antenna array design and beamforming for 3D imaging, localization, and positioning in an advanced wireless system.

The RF transceivers 210a-210n receive, from the antennas 205a-205n, incoming RF signals, such as signals reflected by UEs or any other objects in the network <NUM>. The IF or baseband signals are sent to the RX processing circuitry <NUM>, which generates processed baseband signals by filtering, decoding, digitizing the baseband or IF signals and/or decompressing or correlating. The RX processing circuitry <NUM> sends the processed baseband signals to the controller/processor <NUM> for further processing.

The controller/processor <NUM> can include one or more processors or other processing devices that control the overall operation of the gNB <NUM>. For example, the controller/processor <NUM> could control the reception of forward channel signals and the transmission of reverse channel signals by the RF transceivers 210a-210n, the RX processing circuitry <NUM>, and the TX processing circuitry <NUM> in accordance with well-known principles. The controller/processor <NUM> could support additional functions as well, such as more advanced wireless communication functions. For instance, the controller/processor <NUM> could support beam forming or directional routing operations in which outgoing signals from multiple antennas 205a-205n are weighted differently to effectively steer the outgoing signals in a desired direction. Any of a wide variety of other functions could be supported in the gNB <NUM> by the controller/processor <NUM>.

As a particular example, the ground station (e.g., access point) could include a number of interfaces <NUM>, and the controller/processor <NUM> could support routing functions to route data between different network addresses.

An advanced communication apparatus may refer to a transmitter or receiver array in <FIG>, and <FIG> providing hybrid beamforming operation based on all functional blocks, and may be implemented in <FIG> as a part of a base station (BS, gNB) or <FIG> as a UE.

As shown in <FIG>, the UE <NUM> includes an antenna <NUM>, a radio frequency (RF) transceiver <NUM>, TX processing circuitry <NUM>, and receive (RX) processing circuitry <NUM>. The UE <NUM> also includes a processor <NUM>, an input/output (I/O) interface (IF) <NUM>, a touchscreen <NUM>, a display <NUM>, and a memory <NUM>.

The IF or baseband signal is sent to the RX processing circuitry <NUM>, which generates a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal and/or decompressing or correlating. The RX processing circuitry <NUM> transmits the processed baseband signal to the processor <NUM> for further processing (such as for web browsing data).

The TX processing circuitry <NUM> receives outgoing baseband data (such as web data, e-mail, or interactive video game data) from the processor <NUM>.

The processor <NUM> is also capable of executing other processes and programs resident in the memory <NUM>, such as processes for beam management. 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 <NUM> or in response to signals received from gNBs or an operator. The processor <NUM> is also coupled to the I/O interface <NUM>, which provides the UE <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>.

Part of the memory <NUM> could include a random-access memory (RAM), and another part of the memory <NUM> could include a Flash memory or other read-only memory (ROM).

It is well known that despite its simplicity, code division multiple access (CDMA) system suffers interference and multi-path dispersion.

Benefit of orthogonal frequency division multiplexing (OFDM) over frequency modulated continuous-wave (FMCW) radars is well understood: the waveform is simple to generate, reducing the transceiver complexity compared with FMCW and Chirp sequence modulation; waveform does not require linear frequency generation in hardware; unlike phase modulated signals, which are susceptible to self-interference and multi-path interference, OFDM waveform does not have stringent phase noise requirements, nor does it suffer from multi-path interference; and OFDM is ideally suited for MIMO processing.

Despite the benefits, OFDM signal generation and processing for a high-resolution radar is challenging due to the wide bandwidth processing required for high-resolution radars. Automotive radars in <NUM>-<NUM> has signal bandwidth of <NUM> to <NUM>, requiring analog-to-digital converting (ADC) rate exceeding 10Gsps with large number of bits. For 3D radar imaging requiring <NUM>'s to <NUM>'s channels, wideband OFDM radar systems are cost prohibitive. As such, commercially available radar transceivers rely on FMCW signal.

<FIG> illustrates an example 2D virtual antenna array for imaging <NUM> in accordance with the present disclosure. An embodiment of the 2D virtual antenna array for imaging <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> illustrates an example two dimensional (2D) virtual antenna array for imaging in accordance with the present disclosure. As illustrated in <FIG>, a 2D virtual antenna array for imaging includes a transmit (Tx) antenna <NUM> and a receive (Rx) antenna <NUM>. At a transmitter, Azimuth beamforming with one dimensional (1D) linear array is performed and a sequential scanning is performed in Azimuth. At a receiver, a vertical beamforming for vertical resolution is performed. As illustrated in <FIG>, <NUM> channel angles of arrival (AoA) antennas are provided. In one embodiment, a 2D virtual antenna array can use a MIMO antenna array (e.g., <NUM>/<NUM>/<NUM> orthogonal channels). As discussed above, a 2D virtual antenna array may have benefits: reduction from N<NUM> paths to 2N paths (e.g., small number of ADC/DAC and lower power consumption in transceiver); antenna size reduction and antenna design; and associated reduction in circuitry for DAC/ADC, IF and power consumption. The virtual antenna <NUM> may show the Tx antenna <NUM> and the Rx antenna <NUM>.

<FIG> illustrates an example synthesizing larger aperture in Azimuth <NUM> in accordance with the present disclosure. An embodiment of the synthesizing larger aperture in Azimuth <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure. As shown in <FIG>, the synthesizing larger aperture in Azimuth <NUM> includes Rx antenna <NUM> and synthesized antenna array <NUM>.

<FIG> illustrates another example synthesizing larger aperture in Azimuth <NUM> in accordance with the present disclosure. An embodiment of the synthesizing larger aperture in Azimuth <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure. As shown in <FIG>, the synthesizing larger aperture in Azimuth <NUM> includes Rx antenna <NUM> and synthesized antenna array <NUM>.

<FIG> and <FIG> illustrate an example synthesizing larger aperture in Azimuth in accordance with the present disclosure. As illustrated in <FIG>, a number of transmit paths is reduced from M<NUM>N to M + MN (M: antenna array size, N: number of Rx antenna columns). For example, for M=<NUM>, N=<NUM>, <NUM> paths are reduced to <NUM> paths (Saving by <NUM>%) and for M=<NUM>, N=<NUM>, <NUM> paths are reduced to <NUM> paths (Saving by <NUM>%). As illustrated in <FIG>, the Rx antenna <NUM> and the Tx antenna <NUM> may be synthesized into the synthesized antenna array <NUM>.

<FIG> illustrates synthesizing larger aperture in Azimuth that may provide adjustable vertical field of view. As illustrated in <FIG>, the Rx antenna <NUM> and the Tx antenna <NUM> may be synthesized into the synthesized antenna array <NUM>.

<FIG> illustrates an example automotive antenna design <NUM> in accordance with the present disclosure. An embodiment of the automotive antenna design <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure. As shown in <FIG>, the automotive antenna design <NUM> includes Tx antenna <NUM> and Rx antenna <NUM>.

<FIG> illustrate another example automotive antenna design <NUM> in accordance with the present disclosure. An embodiment of the automotive antenna design <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> and <FIG> illustrate an example automotive antenna design in accordance with the present disclosure.

As illustrated in <FIG>, a <NUM>×<NUM> virtual array is shown for an automotive antenna design, for example, at <NUM>. As illustrated in <FIG>, the <NUM>×<NUM> virtual array includes an antenna panel for Tx comprising <NUM> elements in Azimuth and <NUM> element arrays in elevation, and <NUM> vertical arrays for Rx. As illustrated in <FIG>, Tx antenna <NUM> and Rx antenna <NUM> may be arranged to <NUM> elements <NUM>. As illustrated in <FIG>, the rearview mirror <NUM> may install the <NUM> elements <NUM>. The rearview mirror may be composed of each layer <NUM>.

As illustrated in <FIG>, a <NUM>×<NUM> virtual array is shown for an automotive antenna design, for example, at <NUM>. As illustrated in <FIG>, the <NUM>×<NUM> virtual array includes an antenna panel for Tx comprising <NUM> elements in Azimuth and <NUM> element arrays in elevation, and <NUM> vertical arrays for Rx comprising <NUM> elements in elevation. The <NUM>×<NUM> virtual array as illustrated in <FIG> can be extended to include two or more Tx antenna arrays (rows) for adjustable vertical angle of departure.

As illustrated in <FIG>, Tx antenna <NUM> and Rx antenna <NUM> may be arranged to M elements <NUM>. As illustrated in <FIG>, the car bumper <NUM> with the bumper cover <NUM> may install the M elements <NUM>.

<FIG> illustrates an example virtual 2D circular antenna array <NUM> in accordance with the present disclosure. An embodiment of the virtual 2D circular antenna array <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> illustrates an example virtual 2D circular antenna array in accordance with the present disclosure. As illustrated in <FIG>, a pole, a lamp post, and a rooftop installation can be achieved for <NUM>-degree coverage. As illustrated in <FIG>, the circular antenna array <NUM> comprises M Tx elements and N Rx elements <NUM>. The circular antenna array <NUM> may be configured in the pole and lamp post <NUM>.

<FIG> illustrates an example automotive installation of imaging radar <NUM> in accordance with the present disclosure. An embodiment of the automotive installation of imaging radar <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> illustrates an example automotive installation of imaging radar in accordance with the present disclosure. As illustrated in <FIG>, multiple options for installing imaging radar can be provided for an automotive object <NUM>.

<FIG> illustrates an example in-building installation and factory automation <NUM> in accordance with the present disclosure. An embodiment of the in-building installation and factory automation <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> illustrates another example in-building installation and factory automation <NUM> in accordance with the present disclosure. An embodiment of the in-building installation and factory automation <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, antennas can be installed along <NUM> corners for in-building installation and factory automation. As illustrated in <FIG>, a transmission is performed using a transmit (Tx) antenna <NUM> comprising antenna aperture <NUM> and a reception is performed using a receive (Rx) antenna <NUM> comprising antenna aperture <NUM>. In one embodiment, a transmission is performed using a transmit (Tx) antenna comprising antenna aperture <NUM> and a reception is performed using a receive (Rx) antenna comprising antenna aperture <NUM> (e.g., vice versa).

As illustrated in <FIG>, one antenna element per aperture can be implemented. In one embodiment, antenna element in aperture <NUM> moves along x-axis (e.g., Tx antenna <NUM>) while transmitting the signal illuminating the objects in the room. In such embodiment, signal for each antenna element is weighted according to beamforming equation given by the present disclosure.

In one embodiment, for each antenna element location in aperture <NUM>, antenna element in aperture <NUM> moves along y-axis (e.g., Rx antenna <NUM>) while receiving the signal reflected from the target. In such embodiment, signal for each antenna element is weighted according to beamforming equation given by the present disclosure.

<FIG> illustrates an example beamformer illumination principle <NUM> in accordance with the present disclosure. An embodiment of the beamformer illumination principle <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, transmission beams <NUM> are illuminated at a transmitter in sequential scan fashion and receive beams <NUM> are simultaneously illuminated at a receiver.

<FIG> illustrates an example hybrid beamforming general architecture <NUM> in accordance with the present disclosure. An embodiment of the hybrid beamforming general architecture <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the hybrid beamforming general architecture <NUM> may be implemented as a system or the hybrid beamforming general architecture <NUM> may be implemented as one of components of the system.

As illustrated in <FIG>, a hybrid beamformer circuit comprises a sequence generation block <NUM>, a modulation block <NUM>, a digital BF block <NUM>, an IF/DAC block <NUM>, and an analog BF block <NUM>. As illustrated in <FIG>, a sub-band precoding (W<NUM>) and a wideband precoding (W<NUM>) are determined. In such case, the wideband precoding (W<NUM>) is divided into two parts as provided by: <MAT>.

<FIG> illustrates an example hybrid beamforming with OFDM waveform <NUM> in accordance with the present disclosure. An embodiment of the hybrid beamforming with OFDM waveform <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the hybrid beamforming with OFDM waveform <NUM> may be implemented as a system or the hybrid beamforming with OFDM waveform <NUM> may be implemented as one of components of the system.

As illustrated in <FIG>, a hybrid beamformer circuit with OFDM waveform comprises a sequence generation block <NUM>, a modulation block <NUM>, an RE mapping block <NUM>, an IFFT/CP block <NUM>, a digital BF block <NUM>, an IF/DAC block <NUM>, and an analog BF block <NUM>. As illustrated in.

<FIG>, a sub-band precoding (W<NUM>) and a wideband precoding (W<NUM>) are determined. In such case, the wideband precoding (Wi) is divided into two parts as provided by: <MAT>.

<FIG> illustrates an example hybrid beamforming with MIMO OFDM waveform <NUM> in accordance with the present disclosure. An embodiment of the hybrid beamforming with MIMO OFDM waveform <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the hybrid beamforming with MIMO OFDM waveform <NUM> may be implemented as a system or the hybrid beamforming with MIMO OFDM waveform <NUM> may be implemented as one of components of the system.

As illustrated in <FIG>, a hybrid beamformer circuit with OFDM waveform <NUM> comprises a sequence generation block <NUM>, a layer mapping block <NUM>, a sub-band precoding block <NUM>, a set of resource element mapping blocks <NUM>, <NUM>, a set of IFFT/CP blocks <NUM>, <NUM>, a digital BF block <NUM>, an IF/DAC block <NUM>, and an analog BF block <NUM>.

As illustrated in <FIG>, a hybrid beamformer circuit with MIMO OFDM waveform comprises a sequence generation and modulation block, a layer mapping block, a sub-band precoding block, a plurality of RE mapping blocks, a plurality of IFFT/CP blocks, a digital BF block, an IF/DAC block, and an analog BF block. As illustrated in <FIG>, a sub-band precoding (W<NUM>) and a wideband precoding (W<NUM>) are determined. In such case, the wideband precoding (W<NUM>) is divided into two parts as provided by: <MAT>.

<FIG> illustrates an example beamforming with virtual antenna array <NUM> in accordance with the present disclosure. An embodiment of the beamforming with virtual antenna array <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, a beamforming with virtual antenna array is performed using N Rx elements <NUM> and M Tx elements <NUM>.

<FIG> illustrates an example transmit beamforming <NUM> in accordance with the present disclosure. An embodiment of the transmit beamforming <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, a Tx beamforming circuit includes a plurality of baseband signal input <NUM>, a set of adder block <NUM>, <NUM>, and an IF/DAC block <NUM> connected to a plurality of Tx antenna array (M, <NUM>) elements. In <FIG>, it is assumed that simple antenna array with digital beamformer is considered.

<FIG> illustrates an example receive beamforming <NUM> in accordance with the present disclosure. An embodiment of the receive beamforming <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, an Rx beamforming circuit includes a plurality of Rx antenna array (N, <NUM>) <NUM> and an IF/ADC block <NUM> comprising a plurality of output signals to be added to generate a baseband signal using a set of adders <NUM>, <NUM>. In <FIG>, it is assumed that simple antenna array with digital beamformer is considered.

<FIG> illustrates an example receive beamforming with M antenna arrays <NUM> in accordance with the present disclosure. An embodiment of the receive beamforming with M antenna arrays <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, an Rx beamforming with M antenna arrays circuit includes a plurality of Rx antenna array (N, <NUM>) <NUM>, an IF/ADC block <NUM> comprising a plurality of output signals to be added to generate a baseband signal using a set of adders <NUM>, <NUM>. In <FIG>, it is assumed that simple antenna array with digital beamformer is considered.

<FIG> illustrates an example multi-beam illumination and scheduling <NUM> in accordance with the present disclosure. An embodiment of the multi-beam illumination and scheduling <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, a multi-beam illumination and scheduling is determined in elevation and Azimuth. As illustrated in <FIG>, a multiple-beam illumination in Azimuth at Tx includes digital BF or Butler matrix. As illustrated in <FIG>, <FIG>, <FIG>, or <FIG> simultaneous beams are illuminated in practice for a target scene <NUM> from an antenna <NUM>. Receiver processes are simultaneously performed for multiple Azimuth and elevation angles. In such case, a receiver can process the entire field-of-view (FoV) <NUM> in elevation. As illustrated in <FIG>, a beam scheduling determines Azimuth and/or elevation angles based on a configuration parameter. In such case, the beam scheduling can be dynamically adjusted based on previous results (e.g., tracking objects in certain areas).

<FIG> illustrates an example apparatus <NUM> in accordance with the present disclosure. An embodiment of the apparatus <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the apparatus <NUM> may be implemented as a system or the apparatus <NUM> may be implemented as one of components of the system.

As illustrated in <FIG>, an apparatus comprises a <NUM> modem <NUM>, a mmWave imaging sensor <NUM>, and an advanced driver assistance system/autonomous vehicle (ADAS/AV) central processor <NUM>. The ADAS/AV central processor 2228may be connected with the mmWave imaging sensor <NUM> through the network such as Ethernet. The ADAS/AV central processor 2228is further connected to the modem (e.g., <NUM>) <NUM> that is connected to the mmWave imaging sensor <NUM>. The ADAS/AV central processor 2228may be connected with a display <NUM> and/or a computer (e.g., terminal, device, etc.) <NUM> including at least one peripheral device. The ADAS/AV central processor 2228may be further connected with another processor (e.g., controller) that may be implemented in an external device and/or object (e.g., a vehicle).

The mmWave imaging sensor <NUM> of the apparatus comprises: an antenna block <NUM> including antenna array <NUM>; a transceiver block <NUM> including a filter <NUM>, a power amplifier (PA) <NUM>, a low noise amplifier (LNA) <NUM>, an analog to digital converter/digital to analog converter (ADC/DAV) <NUM>, and a digital beamforming (BF) <NUM>; and a system on chip (SoC) block <NUM> including a 3D imaging modem <NUM>, core post processing sensor fusion <NUM>, and a camera <NUM>.

The ADAS/AV central processor 2228of the apparatus comprises an image processing block2230 , a central processing unit (CPU) <NUM>, a graphics processing unit (GPU) computer vision/machine learning (ML) <NUM>, an internal memory <NUM>, a fabric <NUM>, a video codec H. <NUM><NUM>, a connectivity CAN/SAR Ethernet <NUM>, a security block <NUM>, an external memory interface <NUM>, and a system control block <NUM>.

<FIG> illustrates an example sensor and application software <NUM> in accordance with the present disclosure. An embodiment of the sensor and application software <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, an apparatus including beam pattern <NUM>, a sensor, a 3D imaging modem <NUM>, a transceiver and an antenna array <NUM> (e.g., detail structure shown in <NUM>), and application software <NUM> implemented on COTS hardware <NUM> are configured for a sensor fusion, a stitching, a computer vision, machine learning, a 3D map generation, a data aggregation, and a system control.

<FIG> illustrates an example frame structure of radar waveform <NUM> in accordance with the present disclosure. An embodiment of the frame structure of radar waveform <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> shows the frame structure of digital radar waveform. A "slot" <NUM> is composed of cyclic prefix (CP), multiple OFDM symbols generated by DFT spreading of one or multiple CAZAC sequences, and guard time (GT). The GT is added depending on the required sequence length, and the range of interest for the target scene. In Format <NUM>, only one sequence period is shown. A set of slots forms a sub-frame <NUM>. A set of sub-frames forms a frame <NUM>.

Range processing performs correlation processing of the received OFDM symbols relative to the transmitted coded signal, followed by coherent accumulation of the OFDM symbols within a slot. An OFDM symbol length is determined as the inverse of sub-carrier spacing, while a slot length is set within the channel coherence time. As an example, for <NUM> RF bandwidth with <NUM> sub-carrier spacing, FFT size is <NUM> points, OFDM symbol length is <NUM>µsec, and channel coherence time is <NUM>µsec and <NUM>µsec for velocities 350kmph and 175kmph, respectively.

Multiple slots constitute sub-frames, which are used for Doppler processing. Each sub-frame signal illuminates the targets within its antenna footprint (or beam in scanning radar) resulting in reflection. A complete illumination of the target scene within the field-of-view results in a frame. A target scene is scanned multiple times, resulting in frame rate of <NUM> to <NUM> frames per second.

<FIG> illustrates an example image radar <NUM> in accordance with the present disclosure. An embodiment of the image radar <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the image radar <NUM> includes Rx antenna array <NUM>, a target scene <NUM>, and Tx antenna array <NUM>.

In conventional radar imaging, each beam may scan the target scene of interest sequentially. In 2D imaging, the target is illuminated with a narrow beam illuminating an area with a narrow transmit beam. For each illuminated area, the receiver scans the target area sequentially and estimates the angle-of-arrival. In analog beamforming, typically, single beam is generated due to required hardware complexity. In high-resolution imaging, the number of angle bins to be scanned is <NUM>'s to <NUM>'s of points, requiring long acquisition time to generate point cloud image.

For each dwell, target scene is illuminated by the antenna and received signal from the Rx antenna is processed for imaging.

<FIG> illustrates an example wave form MIMO/beamforming radar transmission <NUM> in accordance with the present disclosure. An embodiment of the wave form MIMO/beamforming radar transmission <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> shows the waveform for MIMO/beamforming radar transmission. MIMO/beamforming radar waveform is generated by a coded digital waveform generated by encoding of the signal in frequency-domain in case of OFDM radar waveform, or in time-domain in case of phase modulated radar. "Signature" <NUM> denotes the slot signal from orthogonal CAZAC sequences. The signature is beamformed by a digital beamformer or hybrid beamformer which is a combination of digital and analog beamformer. After beamforming, multiple streams of signal mapped to the beams <NUM> are transmitted simultaneously, where each beam illuminates a portion of the target scene. As illustrated in <FIG>, the signatures <NUM> and the beams <NUM> are processed through a digital BF <NUM>, an IF/DAC <NUM>, and an analog BF <NUM>.

<FIG> illustrates an example MIMO/BF imaging radar in beamforming mode <NUM> in accordance with the present disclosure. An embodiment of the MIMO/BF imaging radar in beamforming mode <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

Multiple beams are generated simultaneously with digital beamforming. Thus, it is possible to obtain multiple points per scan. At the transmitter, multiple beams are generated illuminating portion(s) of the target scene with each beam using Tx antenna array <NUM>. In reality, signals from these beams interfere with each other, causing inter-beam interference. These appear as artifacts in the resulting imagery. At the receiver, signals are received at Rx Antenna array <NUM> through a target scene <NUM>.

In the present disclosure, multiple CAZAC sequences generated by DFT-Spread OFDM are mapped to different beams. Sequences are mapped to each beam according to following two approaches.

In one embodiment, multiple root CAZAC sequences are mapped to each beam. This ensures that received signal after correlation processing has low auto-correlation value, minimizing inter-beam interference.

In another embodiment, orthogonal CAZAC sequences with zero autocorrelation property are generated by cyclic shift of the root CAZAC sequence. These sequences are mapped to each beam.

Multiple sequences are transmitted on multiple beams simultaneously. At the receiver, multiple correlators corresponding to multiple sequences are implemented for each beam. The receiver can process up to MxN correlators, where M is a number of transmit beams (=number of CAZAC sequence) and N is a number of receive beams.

In one example, where M=N=<NUM>, <NUM> beams are transmitted simultaneously. At the receiver, spatial processing for <NUM> beams, each computing correlation for <NUM> CAZAC sequences are implemented. This approach generates <NUM> points of point cloud for each dwell time, reducing the acquisition time by 16th.

<FIG> illustrates an example multi-stream beamforming radar processing <NUM> in accordance with the present disclosure. An embodiment of the multi-stream beamforming radar processing <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the multi-stream beamforming radar processing <NUM> may be implemented as a system or the multi-stream beamforming radar processing <NUM> may be implemented as one of components of the system.

Details of sequence generation, mapping, and beamforming processing are shown in <FIG> illustrates digital beamforming with multi-beam transmission.

As illustrated in <FIG>, the multi-stream beamforming radar comprises a set of CAZAC sequences <NUM>, a DFT block <NUM>, a complex conjugate block <NUM>, a sub-carrier mapping <NUM>, an IFFT block <NUM>, a CP/GT insertion block <NUM>, a digital Tx beamformer block <NUM>, a DAC block <NUM>, an ADC block <NUM>, an Rx beamformer block <NUM>, a set of blocks <NUM> including a CP removal block <NUM>, an FFT block <NUM>, a complex multiply block <NUM>, an IFFT block <NUM>, and a Doppler DFT block <NUM>, respectively, a CFAR detector block <NUM>, and an arithmetic block <NUM>.

In hybrid beamforming, analog beamforming with phase shifters are implemented in the RF after ADC. The output signals of the digital beamformer are mapped to the antenna ports which is further beamformed with analog beamformer with phase shifter.

In some embodiment, for M transmit and N receive paths, the acquisition time for point cloud is reduced by MxN.

In MIMO mode, multiple antennas illuminate the target scene within the entire field-of-view.

<FIG> illustrates another example multi-stream beamforming radar processing <NUM> in accordance with the present disclosure. An embodiment of the multi-stream beamforming radar processing <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

CAZAC sequence is mapped to each antenna port in MIMO configuration. Block diagram of multi-stream MIMO radar is shown in <FIG>.

As illustrated in <FIG>, the multi-stream beamforming radar comprises a set of CAZAC sequences <NUM>, a DFT block <NUM>, a complex conjugate block <NUM>, a sub-carrier mapping <NUM>, an IFFT block <NUM>, a CP/GT insertion block <NUM>, a DAC block <NUM>, an ADC block <NUM>, a set of blocks <NUM> including a CP removal block <NUM>, an FFT block <NUM>, a complex multiply block <NUM>, an IFFT block <NUM>, and a Doppler DFT block <NUM>, respectively, a special processing block <NUM>, a CFAR detector block <NUM>, and an arithmetic block <NUM>.

Multiple orthogonal CAZAC sequences generated by DFT-spread OFDM are mapped to antenna ports. In the receiver, Range/Doppler processing is achieved for each antenna port. After range/Doppler processing, spatial processing takes the data from multiple antenna ports and focuses the image depending on the range. Spatial focusing applies range-dependent correction factor to the range/Doppler compressed data. In one embodiment, a computationally efficient image focusing algorithm with FFT may be applied as shown in the aforementioned embodiments.

<FIG> illustrates an example simultaneous operation of short-range and long-rang radar <NUM> in accordance with the present disclosure. An embodiment of the simultaneous operation of short-range and long-rang radar <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

For objects located close to the transmit antenna, received SINR is high. Multiple MIMO streams are transmitted with large field-of-view, illuminating wide field of view up to <NUM>°.

As illustrated in <FIG>, a car <NUM> transmit beam in a short-range <NUM>, in a medium-range <NUM>, and in a long-range <NUM>.

In one embodiment, for simultaneous short-range and long-range operation, MIMO and beamforming mode transmission and reception applies alternating dwell times. At even subframe number, MIMO transmission and reception takes place. At odd subframe number, beamforming transmission and reception takes place.

In one embodiment, for simultaneous short-range, medium-range, and long-range operation, MIMO, MIMO and beamforming, and beamforming transmission/reception applies sequentially within a subframe.

In one embodiment, at the receiver, a spatial processing is performed for the target distance after range/Doppler processing.

<FIG> illustrates an example range dependent imaging operation <NUM> in accordance with the present disclosure. An embodiment of the range dependent imaging operation <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> shows the principle of range dependent imaging operation. Different spatial processing depending on range applies after range-Doppler processing.

<FIG> illustrates an example geometry of image formation <NUM> in accordance with the present disclosure. An embodiment of the geometry of image formation <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, an antenna array <NUM> transmit signal to a target scene <NUM>.

In one embodiment, a digital imaging module performs computational imaging operations such as an image formation algorithm to determine the target reflectivity, which is the fraction of a signal (e.g., electromagnetic or optical signal) incident to the target that is reflected from the target. The digital imaging module thus uses the image formation algorithm to calculate voxels (volume pixel) having coordinates (x, y, r) to generate a <NUM>-D image of a far field scene being illuminated by the <NUM>-D imaging sensor of the present disclosure. The (x, y, r) coordinates are calculated using a <NUM>-D Fast Fourier Transform of the reflectivity density ρ, which is the reflection of the signal that is impinging on a target segment per infinitesimal volume dζdηdr. The electivity density of the target can thus be modeled as a function of the three variables, (ζ, η,) as will be discussed below.

The image formation algorithm also makes adjustments made to the resultant phase shifts of the reflected transmit signals reflected or backscattered by the far field scene. The adjustments reduce or significantly eliminate the resultant phase shifts experienced by the transmit signals after they were emitted by an energy emitting element of the Array, to a far field scene, reflected or backscattered by the scene and received by one or more energy detector element of the Array.

In one embodiment, a value for the coordinate r associated for each adjusted (x, y) set of coordinates is also calculated by the image formation algorithm by performing a <NUM>-D FFT of the reflectivity density of a target from which a transmitted signal by the <NUM>-D imaging sensor is reflected. Thus, for each value of r calculated, i.e., r = R<NUM>, R<NUM>, R<NUM>,. RN, for a particular (x, y) coordinate, there is a corresponding voxel (x, y, R<NUM>), (x, y, R<NUM>) that can be computed by the <NUM>-D imaging sensor of the present disclosure thus generating a <NUM>-D image of a far field scene. The coordinate r represents a distance between the corresponding energy detector element (element detecting the reflected transmit signal) having coordinates (x, y) and a target point of a far field scene being illuminated by the transmit signals emitted by the array. The transmitted signal is reflected (or backscattered) by the target point and is then detected by one or more energy detector elements of the array having a coordinate of (x, y).

For that particular set of coordinates, the <NUM>-D imaging sensor of the present disclosure calculates the r value for different values of r (r=R<NUM>, r=R<NUM>, r=R<NUM>,. ) in the process of generating a <NUM>-D image of the far field scene being illuminated. The resulting voxels thus have coordinates (x, y, R<NUM>), (x, y, R<NUM>), (x, y, RN) where N is an integer equal to <NUM> or greater.

In one embodiment, a transmit signal comprises a digitally beam formed orthogonal digital waveform modulated by a MIMO processed frequency domain PN sequence (e.g., orthogonal MIMO signals), said digitally beam formed orthogonal digital waveform is converted to an analog waveform signal caused to modulate an energy source resulting in a modulated signal that is then analog beam formed to obtain the transmit signal applied to the one or more energy emitter elements of the array. The operation of analog beam forming comprises applying a signal directly to an element of the array to provide a certain phase value to the element. The phase of that element does not change until the signal (e.g., voltage, current) is no longer applied.

The receiver is configured to detect energy received by the energy detector elements of the array and demodulate the received signals to derive the baseband signal from the received signals. The receiver is further configured to perform operations comprising computational imaging on a received digital signal to generate one or more <NUM>-D images of objects, structures or an overall scene from which the transmit signals are reflected. The objects, structures, or other items of the scene are located in the far field with respect to the array.

The computational imaging comprises at least an image formation algorithm for making adjustments to the resultant phase shift experienced by the reflected or backscattered transmitted signal received by one or more energy detector elements of the array and for generating a <NUM>-D image of the received reflected or backscattered signal through the use of a <NUM>-D FFT operation performed on the signal. In particular, the received transmitted signal is detected and the baseband signal is retrieved through demodulation. The signal is then converted to a digital signal with the use of an analog to digital converter. The <NUM>-D FFT operation is then performed on the digital signal to generate the <NUM>-D image of a scene in a far field being illuminated by the <NUM>-D imaging sensor.

The <NUM>-D image is based on illumination of target locations of objects, structures or other items in the scene being illuminated. Clearly, each target location does not necessarily have the same distance. The distance between an energy detector element of the array and a target location may change and most often does for different target locations. For example, the distance may be R for a first target location, then changes to R<NUM> for another location and then R<NUM> for yet another location. The coordinates (x, y) and calculated (r) coordinate result in (x, y, r) coordinates representing voxels (volume pixels) of a <NUM>-D image of a target of an object being illuminated by the transmit signal from the <NUM>-D imaging sensor of the present disclosure. A <NUM>-D image of the object is thus obtained.

<FIG> illustrates an example image formation algorithm <NUM> in accordance with the present disclosure. An embodiment of the image formation algorithm <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, DFFT <NUM> is used to generate an output signal.

In one embodiment of short-range imaging, for a transmission, MIMO transmission with <NUM> layers is provided, and for reception, MIMO reception with <NUM> layers followed by distance dependent spatial processing according to near-field image formation algorithm is provided as shown in the aforementioned embodiments.

In one embodiment of medium-range imaging, for transmission, MIMO with beamforming transmission with <NUM> layers per beam is provide, and for reception, MIMO reception with <NUM> layers per beam followed by receive beamforming is provided.

In one embodiment of long-range imaging, for transmission, beamforming with single layer transmission is provide, and for reception, single layer receive beamforming per beam is provided.

In the present disclosure, multi-stream transmission and reception schemes for high-resolution radar are provided. The present disclosure allows transmission and reception of the signal in multiple beams in beamforming mode, or multiple antennas in MIMO mode, without interference between the beams or antennas. The present disclosure reduces the acquisition time by MxN fold, where M is a number of transmit beams (or MIMO layers) and N is a number of received beams (or MIMO layers). This present disclosure provides embodiments that may be applied for high-resolution imaging radar in automotive applications, where large number of channels and frame rate is required.

MIMO radar is promising for near-field imaging applications, where SINR is large. The present disclosure allows general image focusing algorithm after range/Doppler processing, allowing high-resolution images without artifacts.

For M=N=<NUM>, <NUM>-fold reduction in acquisition time is possible compared with conventional approach with scanning analog Tx/Rx beams, or <NUM>-fold reduction in case of multiple beams without <NUM>-stream transmission.

Next generation radar system technologies comprise new waveforms such as an orthogonal frequency division multiplexing (OFDM) and a code division multiple access (CDMA); multi-input multi-output (MIMO) antennas with digital beamforming; 3D/4D imaging; and simultaneous communication and radar.

It is well known that despite its simplicity, a CDMA system suffers interference and multi-path dispersion, and is susceptible to a phase noise. Benefits of OFDM over frequency-modulated continuous-wave (FM-CW) radars are well understood.

In such radar systems, the waveform is simple to generate, reducing a transceiver complexity compared with a FM-CW and Chirp sequence modulation. In such radar systems, a waveform does not require linear frequency generation in hardware. In such radar systems, unlike phase modulated signals, which is susceptible to self-interference and multi-path interferences, an OFDM waveform does not have stringent phase noise requirements, nor does it suffer from multi-path interferences. In such radar systems, an OFDM is ideally suited for MIMO processing.

Despite the benefits, OFDM signal generation and processing for high-resolution radars are challenging due to wide bandwidth processing required for the high-resolution radars. Automotive radars in <NUM>-<NUM> has a signal bandwidth of <NUM> to <NUM>, requiring an analog-to-digital (ADC) rate that exceeds 10Gsps with a large number of bits.

A cost of a <NUM>-bit 10Gsps ADC is about $<NUM>,<NUM>. For 3D radar imaging requiring <NUM>'s to <NUM>'s channels, wideband OFDM radar systems are cost prohibitive. As such, commercially available radar transceivers rely on FMCW signals.

<FIG> illustrates an example power dissipation per transmit and receive paths in a mmWave transceiver <NUM> in accordance with the present disclosure. An embodiment of the power dissipation per transmit and receive paths in a mmWave transceiver <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

Another consideration is power consumption. Power consumption analysis of state-of-art mmWave OFDM system is shown in <FIG>.

As illustrated in <FIG>, power amplifier (PA) and radio frequency-ADC (RF-ADC) account for <NUM>% and <NUM>% of power dissipation in transmit and receive paths, respectively. Low-power PA and simpler ADC design is critical in a transceiver design. As illustrated in <FIG>, power dissipation per transmit path (e.g., <FIG>) and power dissipation per receive path (e.g., <FIG>) are provided.

In one embodiment, a scheme for a sub-channel coded OFDM with aggregation is provided. In such embodiment, the scheme for the sub-channel coded OFDM with aggregation retains performance benefits of a wideband OFDM system, while reducing complexity associated with a wide bandwidth signal, for efficient multi-stream MIMO/beamforming radar, as may be performed by a system.

An OFDM system requires real-time implementation of fast Fourier transform/inverse fast Fourier transforms (FFT/IFFTs). For wide band radar with up to <NUM> bandwidth, high range resolution requires the signal at sampling rate of <NUM>. 5ns, <NUM> ns or faster is processed.

Automotive applications with range of up to <NUM> require computation of range processing every <NUM>µsec. At a transmitter, time-domain signal can be pre-computed for DAC and modulation so that there may not issues in real-time computation.

However, for a receiver, <NUM> and <NUM> FFT/IFFT and complex multiplication followed by CFAR detection is required per path for <NUM> and <NUM> bandwidths, respectively. Although complexity of the receiver is lower than a time-domain PM radar, significant computational burden for real-time implementation of state-of-art field-programmable gate arrays (FPGAs) or application-specific integrated circuit (ASIC) is caused.

In conventional radars, "stretch processing" is employed for range processing to reduce signal processing requirements. The "stretch processing" uses a longer time frame to sweep radar bandwidths, slowing down transmit/receiver processing operation. However, this approach is not applicable to automotive radars, where a sequence length and a required range are comparable. The "stretch processing" would reduce the maximum range of radar systems.

In one embodiment, exploiting CAZAC waveform with circular correlation property, a computationally efficient receiver is provided to reduce computational complexity of range processing by more than <NUM> times for real-time implementation on FGPA and ASIC.

<FIG> illustrates an example 4D imaging radar <NUM> in accordance with the present disclosure. An embodiment of the 4D imaging radar <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the imaging radar <NUM> may be implemented as a system or the imaging radar <NUM> may be implemented as one of components of the system.

As illustrated in <FIG>, the 4D imaging radar <NUM> comprises a PN sequence generator block <NUM>, a DFT block <NUM>, a MIMO codeword mapping block <NUM>, a layer mapping block <NUM>, a MIMO precoding block <NUM>, a set of RE mapping blocks <NUM>, a set of IFFT/CP blocks <NUM>, a digital BF Tx block <NUM>, a DAC block <NUM>, an energy source <NUM>, a modulator block <NUM>, a set of analog blocks <NUM>, a Tx and Rx antenna block <NUM>, an energy detection and demodulation block <NUM>, an ADC block <NUM>, an adder block <NUM>, a 2D FFT block <NUM>, an adder block <NUM>, a complex conjugator block <NUM>, a DFT block <NUM>, an IFFT block <NUM>, an arithmetic block <NUM>, a threshold block <NUM>, a post processing block <NUM>, a tracking block <NUM>, and a lookup table block <NUM>.

<FIG> illustrates an example antenna array <NUM> in accordance with the present disclosure. An embodiment of the antenna array <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the antenna array <NUM> includes a set of antenna arrays 3526A, 3526B.

As illustrated in <FIG>, a frame structure of digital radar waveform is illustrated. A "slot" is composed of cyclic-prefix (CP), multiple OFDM symbols generated by discrete Fourier transform (DFT) spreading of one or multiple CAZAC sequences, and guard time (GT). The GT is added based on a required sequence length, and a range of interest for a target scene.

Multiple sequence periods each comprising OFDM symbol are present in a slot.

Range processing performs correlation processing of the received OFDM symbols relative to the transmitted coded signal, followed by coherent accumulation of OFDM symbols within a slot.

An OFDM symbol length is determined as inverse of sub-carrier spacing, while a slot length is set within a channel coherence time. As an example, for <NUM> RF bandwidth with <NUM> sub-carrier spacing, an FFT size is <NUM> points, an OFDM symbol length is <NUM>µsec, and a channel coherence time is <NUM>µsec and <NUM>µsec for velocities 350kmph and 175kmph, respectively.

Multiple slots constitute sub-frames that are used for Doppler processing. Each sub-frame signal illuminates targets within its antenna footprint (or beam in scanning radars) resulting in reflection. A complete illumination of the target scene within field-of-view results in a frame. A target scene is scanned multiple times, resulting in frame rate of <NUM> to <NUM> frames per second.

<FIG> illustrates an example overall transmit/receiver processing architecture <NUM> in accordance with the present disclosure. An embodiment of the overall transmit/receiver processing architecture <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the transmit/receiver processing architecture <NUM> may be implemented as a system or the transmit/receiver processing architecture <NUM> may be implemented as one of components of the system.

As illustrated in <FIG>, the transmit/receiver processing architecture <NUM> comprises a Tx antenna <NUM>, a Rx antenna <NUM>, an LPF <NUM>, <NUM>, an LO block <NUM>, a DAC block <NUM>, an ADC block <NUM>, an IFFT block <NUM>, a FFT block <NUM>, a sub-carrier mapping block <NUM>, an element-wise operation block <NUM>, a DFT block <NUM>, a complex conjugate block <NUM>, an IFFT block <NUM>, and a slow-time FFT block <NUM>. Transmitter and receiver architecture of DFT-spread OFDM radar waveform is shown in <FIG>. A CAZAC sequence is transformed to frequency domain signal for DFT. A frequency-domain CAZAC sequence is mapped to a sub-carrier centered around a zero frequency and transformed back to time-domain signal. The DFT-spread radar signal is converted to analog signal and passed to a low pass filter (LPF) and an IQ mixer, a PA and transmitted through the Tx antenna. At a receiver, signals from an Rx antenna is demodulated and filtered, then converted to baseband signal by ADC.

The range processing is achieved in a frequency domain: received baseband signal is converted to a frequency-domain by FFT, multiplied by the complex conjugate of the DFT version of original CAZAC sequence, followed by time-domain conversion by IFFT, which gives the correlation output corresponding to each range bin.

Doppler processing is applied by taking FFT of the correlation output for each range bin, resulting in a <NUM>-dimensional range-Doppler map.

In the implementation, because signal is pre-computed and stored in a memory, thereby real-time processing requirement is reduced significantly.

At a transmitter, a DFT-spread OFDM waveform after IFFT is pre-computed and stored in a memory. For receiver processing, reference signal that is complex conjugate of DFT-spread CAZAC sequence is pre-computed and stored in a memory and used in range-processing. Real-time processing is in a receiver range and Doppler processing. Particularly, the range processing is the most challenging part in digital radars.

<FIG> illustrates an example frequency-domain range-Doppler processing for a radar waveform <NUM> in accordance with the present disclosure. An embodiment of the frequency-domain range-Doppler processing for a radar waveform <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the frequency-domain range-Doppler processing for a radar waveform <NUM> may be implemented as a system or the frequency-domain range-Doppler processing for a radar waveform <NUM> may be implemented as one of components of the system.

For OFDM systems, a multiple correlation computation is needed for symbols within a slot. <FIG> shows the detailed block diagram of range-Doppler processing of the radar waveform that is provided in the present disclosure.

For automotive radars, sub-carrier spacing is determined by the two-way Doppler of the signal returns. In typical environment, an OFDM symbol length is <NUM>µsec, and a number of OFDM symbols within a slot is set based on a channel coherence time that can be <NUM> to <NUM>. An FFT size is <NUM> and <NUM>, for an RF bandwidth of <NUM> and <NUM>, respectively. With this signal structure, multiple FFT/complex multiplication/IFFT computation is repeated every <NUM>µsec OFDM symbol. This results in a large gate count and huge power consumption.

As illustrated in <FIG>, the frequency-domain range-Doppler processing architecture comprises a DFT block <NUM>, a sub-carrier mapping block <NUM>, an IFFT block <NUM>, a repeat block <NUM>, a CP/GT insertion block <NUM>, a DAC block <NUM>, a complex conjugate block <NUM>, an ADC block <NUM>, a CP removal block <NUM>, an FFT block <NUM>, a complex multiply block <NUM>, an IFFT block <NUM>, a Doppler DFT block <NUM>, a CFAR detector block <NUM>, and an arithmetic block <NUM>.

<FIG> illustrates an example time-domain representation <NUM> of compressed range processing of transmitted signal, received signal, cyclic-shift, and add followed by accumulation operation in accordance with the present disclosure. An embodiment of the time-domain representation <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

In one embodiment, exploiting linearity and periodic correlation property of the signal, computationally efficient receiver processing (e.g., compressed range-processing) is provided. <FIG> illustrates time-domain signal processing of an OFDM slot in the compressed range-processing.

<FIG> shows time-domain representation of compressed range processing of transmitted signal, received signal, cyclic-shift and add followed by accumulation operation. Received signal that falls in GT of a slot is cyclically shifted by the length of the signal (NFFT × Nsymbol), followed by sample-by-sample accumulation of the OFDM symbols within a slot.

As illustrated in <FIG>, the transmitter <NUM> transmits CAZAC sequences and the receiver <NUM> receives the CAZAC sequences.

In such embodiment of step <NUM>, from a baseband receiver, a cyclic prefix is removed from the received signal.

In such embodiment of step <NUM>, the last NFFT samples are taken from the received signal that falls in the guard time.

In such embodiment of step <NUM>, samples are added to the beginning of the signal.

In such embodiment of step <NUM>, sample-by-sample accumulation of OFDM symbols is within a slot.

In such embodiment of step <NUM>, accumulated symbol-length signal is converted to a frequency-domain by for range-processing.

<FIG> illustrates an example compressed range-processing for a radar waveform <NUM> in accordance with the present disclosure. An embodiment of the compressed range-processing for a radar waveform <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the compressed range-processing for a radar waveform <NUM> may be implemented as a system or the compressed range-processing for a radar waveform <NUM> may be implemented as one of components of the system.

As illustrated in <FIG>, the ranging process operation comprises a DFT block <NUM>, a complex conjugate block <NUM>, an IFFT block <NUM>, a complex multiply block <NUM>, an FFT block <NUM>, an add symbol data block <NUM>, and a cyclic-shift, and add block <NUM>.

Block diagram of the compressed range-processing is shown in <FIG>.

<FIG> shows the compressed range-processing for the radar waveform. Frequency-domain correlation (FFT, complex multiplication followed by IFFT) is computed once per slot instead of once per OFDM Symbol.

In one embodiment, compared with conventional linear frequency-domain correlation, a reduction scheme is provided to reduce the complexity in two ways.

In one embodiment, by compressing multiple OFDM symbols to a single accumulated OFDM symbol, complexity is reduced by Nsymbol while processing time is extended from Nsymbol.

In one example, <NUM> frequency-domain correlation (e.g., FFT/complex multiplication/IFFT) is required every <NUM>µsec, instead of every <NUM>µsec.

NFFT -point FFT/complex multiplication/IFFT is needed instead of <NUM>×NFFT -point FFT processing required in linear correlation.

<FIG> illustrates an example computational complexity of range processing <NUM> in accordance with the present disclosure. An embodiment of the computational complexity of range processing <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> shows the comparison of computational complexity of conventional frequency-domain range processing and the compressed range-processing that is provided in the present disclosure.

FIGUIRE <NUM> shows comparison of computational complexity of range processing showing <NUM>-fold reduction in complexity compared with generic frequency-domain approach (Time-domain processing requires <NUM>,<NUM>,<NUM> multiplications and <NUM>,<NUM>,<NUM> multiplications for range processing of a Slot, requiring 1000x complex multiply-adds compared with the proposed approach.

TABLE <NUM> shows system parameters for performance evaluation. The RF bandwidth is assumed to be <NUM>.

<FIG> illustrates an example decision statistic after range-processing for AWGN channel <NUM> in accordance with the present disclosure. An embodiment of the decision statistic after range-processing for AWGN channel <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> illustrates an example slice of decision statistic after range-Doppler processing for AWGN channel <NUM> in accordance with the present disclosure. An embodiment of the slice of decision statistic after range-Doppler processing for AWGN channel <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> shows a result after range-processing, computed using the compressed range-processing that is provided in the present disclosure. An average range side-lobe is approximately -<NUM> dB relative to a peak of the signal.

<FIG> shows the slices of the signal after range-Doppler processing, following the compressed-range processing algorithm that is provide in the present disclosure. The range slice and Doppler slices are shown in the top and bottom plots. The peak and average range side lobes are approximately -50dB and -58dB, respectively. The peak and average Doppler side-lobes are -50dB and - 62dB, respectively.

<FIG> illustrates an example 2D range-Doppler map after range-Doppler processing <NUM> in accordance with the present disclosure. An embodiment of the 2D range-Doppler map after range-Doppler processing <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

<FIG> shows a two-dimensional range-Doppler map after the compressed range-processing followed by Doppler processing, demonstrating a sharp range-Doppler ambiguity function required for high-resolution radars.

The compressed-range processing that is provide in the present disclosure cyclically adds the data from a GT to the first symbol of received signal. Due to the addition, a noise variance of the resulting signal is increased from Nsymbol s<NUM> to (Nsymbol + <NUM>) s<NUM>, where s<NUM> is a noise variance of received complex baseband signal, increasing by <NUM>/Nsymbol. For the system parameters analyzed, this is <NUM>. 5dB, resulting in reduction in SINR by <NUM>.

In the present disclosure, computationally efficient radar receiver architecture is provided for real-time implementation of an OFDM radar with CAZAC sequence coding. The compressed range-processing that is provide in the present disclosure uses cyclic addition and symbol-accumulation processing, resulting in drastic reduction in complex FFT/complex multiply/IFFT processing for efficient real-time implementation with state-of-art FPGA/DSP hardware or low-power, low-complexity ASIC implementation.

In aforementioned embodiments, the complexity is reduced up to <NUM>-fold compared with state-of-art efficient frequency-domain range-processing algorithms. Compared with time-domain processing from conventional PM radars, the complexity of computation is saved more than <NUM> times.

The present disclosure may apply to 4D imaging radars with MIMO and beamforming straightforward by processing per channel at a receiver. The present disclosure may apply to a time domain radar code such as a PM coded radar as long as underlying PM radar waveform has a similar frame structure and the code possessed cyclic correlation property.

In one embodiment of the present disclosure, the <NUM>-D imaging sensor comprises a transmitter, a receiver, and an array coupled to the transmitter and receiver, said array having one or more energy emitter elements and energy detector elements wherein the array is configured to emit a transmit signal generated by the transmitter.

In such embodiment, the transmit signal comprises a digitally beam formed orthogonal digital waveform modulated by a MIMO processed frequency domain PN sequence, said digitally beam formed orthogonal digital waveform is converted to an analog waveform signal caused to modulate an energy source resulting in a modulated signal (i.e., the modulated energy) analog beam formed to obtain the transmit signal applied to the one or more energy emitter elements of the array.

The receiver is configured to perform operations using computational imaging comprising at least an image formation algorithm to generate <NUM>-D images of a far field scene being illuminated by the <NUM>-D imaging sensor of the present disclosure. The image formation algorithm first makes adjustments to resultant phase shifts experienced by signals transmitted from the <NUM>-D imaging sensor and reflected or backscattered by a far field scene. Further, the image formation algorithm performs a <NUM>-D FFT (Fast Fourier Transform) of the reflectivity density of the reflected signals to generate a <NUM>-D image of the scene from which the transmit signals are reflected or backscattered.

Referring now to <FIG>, there is shown another embodiment of the present disclosure. Although not shown, the embodiment of <FIG> may also be operated, controlled or otherwise directed by a processor in a similar fashion as the embodiment of the present disclosure. That is, the processor controlling of the embodiment of <FIG> comprises microprocessors, microcontrollers, a master processor in control of one or a multiple of processors including digital signal processors (DSP), or processors implemented as or are part of field programmable gate arrays (FPGA), application specific integrated circuits (ASICs) or other similar circuitry. Further, the processor may reside on a circuit board that forms part of the image sensor or the processor may be remotely located while still being able to operate, control or otherwise direct any of the modules of <FIG>.

In the embodiment of <FIG>, the <NUM>-D imaging sensor <NUM> comprises a transmitter (modules <NUM> to 3502A inclusive), a receiver (modules 3524B to <NUM> inclusive), and an array <NUM> coupled to the transmitter and receiver, with said array <NUM> having one or more energy emitter elements and energy detector elements wherein the array <NUM> is configured to emit a transmit signal generated by the transmitter.

The Array <NUM> of <FIG> is configured to emit energy in various frequency bands or regions and/or wavelength ranges. For example, the array <NUM> of <FIG> is configured to emit or detect optical signals in the wavelength range of <NUM> to <NUM> inclusive belonging to Near Infrared (NIR) and <NUM> to <NUM> inclusive belonging to short-wave infrared (SWIR). Also, arrays <NUM> are configured to emit or detect electromagnetic signals in one of a high frequency (HF) region or band, a very high frequency (VHF) region, ultra high frequency (UHF), super high frequency (SHF) band, extremely high frequency (EHF) region and a tera hertz (THz) region. The EHF region is particularly suited for simultaneous broad band communications and high-resolution imaging. The term "frequency region" and "frequency band" are used interchangeably.

The front view of array <NUM> is shown in <FIG> depicting array <NUM> comprising four (<NUM>) sub-arrays 3526A, 3526B, 3526C, and 3526D. In general, the array <NUM> may be subdivided into any number of sub-arrays where each sub-array comprises a certain number of array elements. Each sub-array may have the same number of array energy emitter elements and energy detector elements. Also, certain sub-arrays may have different number of elements depending on the location of said sub-arrays within the entire array. For example, a sub-array located at or near the center of the array may have more array elements than any other sub-arrays.

The transmit signal comprises a digitally beam formed orthogonal digital waveform (output of digital beam former Tx <NUM>). Prior to being digitally beam formed, the orthogonal digital waveform is generated by the combination of resource element (RE) mapping modules <NUM> <NUM>,. , <NUM>L coupled to corresponding inverse fast Fourier transform (IFFT) cyclic prefix (CP) modules <NUM><NUM>,. Also, said orthogonal digital waveform is modulated by a multiple input multiple output (MIMO) processed frequency domain pseudo noise (PN) sequence (output of MIMO pre-coding module <NUM>). Thus, the digitally beam formed orthogonal digital waveform is obtained by applying the orthogonal digital waveform to the digital beam former <NUM>.

The digitally beam formed orthogonal digital waveform is converted to an analog waveform by DAC <NUM> (i.e., signal at output of DAC <NUM>). The resulting analog waveform is applied to an input of modulator <NUM> module to modulate an energy source <NUM> resulting in a modulated analog signal that is analog beam formed by Beam Former 3524A to obtain the transmit signal (output of Analog Beam Former 3524A) applied to the one or more energy emitter elements of the Array. The one or more energy emitter elements of the Array <NUM> emit the transmit signals applied to them.

The modulator <NUM> of <FIG> may be configured as any one of the following: binary phase shift keying (BPSK) modulator, quadrature phase shift keying (QPSK) modulator, on off keying (OOK) modulator, amplitude shift keying (ASK) modulator, frequency shift keying (FSK) modulator, pulse position modulation (PPM), phase shift keying (PSK) modulator, and differential phase shift keying (DPSK) modulator.

Still referring to <FIG>, the manufacture of the transmit signal starts with PN sequence generator <NUM>, which generates a time domain PN sequence: S<NUM>, S<NUM>, S<NUM>,. SN-I, which is transformed via discrete Fourier transform (DFT) module <NUM> to a frequency domain PN sequence: X<NUM>, X<NUM>, X<NUM>,. , XN-<NUM> as shown in <FIG>.

The DFT module <NUM> is a circuit or module that performs a Discrete Fourier Transform on a time domain sequence to convert said sequence to a frequency domain sequence. A time domain PN sequence obtained from a CAZAC sequence is one example of a PN sequence that is generated by PN sequence generator <NUM>. A CAZAC sequence is a type of PN sequence having a Constant Amplitude Zero Auto-Correlation (CAZAC) property. The uth root of a Zadoff-Chu sequence, a CAZAC sequence is given by the equation: <MAT>, <NUM> ≤ n ≤ NZC - <NUM> where NZC is the length of the length of the Zadoff-Chu sequence. The frequency domain PN sequence is then MIMO processed.

<FIG> illustrates a flow chart of a method <NUM> for multi-stream MIMO/Beamforming radar in accordance with the present disclosure, as may be performed by a system (e.g., <NUM>-<NUM> and/or <NUM>-<NUM> as illustrated in <FIG>). An embodiment of the method <NUM> shown in <FIG> is for illustration only. One or more of the components illustrated in <FIG> can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions. Other embodiments are used without departing from the scope of the present disclosure.

As illustrated in <FIG>, the method <NUM> begins at step <NUM>. In step <NUM>, the system identifies a set of orthogonal multiple-input-multiple-output (MIMO) signals.

Subsequently, in step <NUM>, the system generates a first set of beams.

Subsequently, in step <NUM>, the system maps the set of orthogonal MIMO signals into each of the generated set of beams.

Next, in step <NUM> the system transmits, to a target scene, a first signal based on the first set of beams.

Finally, in step <NUM>, the system receives a second signal based on a second set of beams that is reflected or backscattered from the target scene.

In one embodiment, the system generates the set of orthogonal MIMO signals including a set of CAZAC sequences based on a set of cyclically shifted CAZAC sequences.

In one embodiment, the system generates the set of orthogonal MIMO signals including a set of MIMO coded signals based on a set of different root CAZAC sequences.

In one embodiment, the system identifies a set of reference signal candidates and calculate a correlation for the set of reference signal candidate.

In one embodiment, the system illuminates, using the set of orthogonal MIMO signals, an entire scene with a same transmit beam of the first set of beams.

In one embodiment, the system identifies signal using range/Doppler process that is computed for the set of orthogonal MIMO signals and performs a spatial process for the identified signal to generate an image.

In one embodiment, the system identifies, based on a targeted range, an operation mode comprising a MIMO operation mode, a hybrid of MIMO and beamforming operation mode, or a beamforming operation mode, transmits, the first signal based on the identified operation mode, and receives, the second signal based on the identified operation mode.

In one embodiment, the system constructs a signal corresponding to an OFDM radar waveform repeating a set of orthogonal frequency division multiplexing (OFDM) symbols; accumulates, in a slot, the set of OFDM symbols using a same code over multiple symbols of the set of OFDM symbols; generates combined signals based on the accumulated set of OFDM symbols; and computes a range correlation for the generated combined signals.

In such embodiment, the system computes the range correlation based on: calculating FFT of the combined signal; computing a complex multiplication of the combined signal and a reference signal; and computing an IFFT of the computed complex multiplicated combined signal to obtain a range correlation.

Claim 1:
A system, the system comprising:
a set of antennas including a set of transmit antennas and a set of receive antennas;
a digital beamformer (<NUM>);
a processor (<NUM>) operably connected to the set of antennas and the digital beamformer (<NUM>), the processor (<NUM>) configured to:
identify a set of orthogonal multiple-input-multiple-output (MIMO) signals,
generate a first set of beams via the digital beamformer (<NUM>), and
map the set of orthogonal MIMO signals into each of the generated set of beams, and
a transceiver (<NUM>) operably connected to the processor (<NUM>), the transceiver (<NUM>) configured to:
transmit, to a target scene via the set of transmit antenna of the set of antennas, a first signal based on the first set of beams;
characterized in that the processor (<NUM>) is further configured to:
illuminate, using the set of orthogonal MIMO signals, the target scene with a same transmit beam of the first set of beams; and
receive, via the set of receive antennas of the set of antennas, a second signal that is reflected or backscattered from the target scene based on a second set of beams
wherein the processor (<NUM>) is further configured to:
identify, based on a targeted range, an operation mode comprising a MIMO operation mode, a hybrid of MIMO and beamforming operation mode, or a beamforming operation mode;
transmit, the first signal based on the identified operation mode; and
receive, the second signal based on the identified operation mode;
and wherein the processor (<NUM>) is further configured to apply the MIMO operation mode and the beamforming operation mode at alternating dwell times for simultaneous short-range and long-range operation.