Patent Description:
A design of the antenna array in a wireless communication system is one of the most important factors that provide higher performance, for example, in <NUM>-dimensional (3D) imaging, localization, and positioning. A synthetic aperture antenna array based on multiple-input multiple-output (MIMO) employs multiple antennas to transmit and receive orthogonal waveforms. Such synthetic aperture antenna array and beamforming may be applied for radar and lidar image processing, imaging/positioning/localization for industrial automation, robotic vision, localization and positioning for communication systems, and antenna array designs for mobile devices and communication systems. <NPL>, discloses a synchronization algorithm for Filter Bank Multi-carrier (FBMC) by using Constant Amplitude Zero Auto Correlation (CAZAC) sequencing. <CIT> discloses a joint communication and radar system, in which pilot signals are re-used as radar probe pulses.

This disclosure provides new waveforms such as orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA), MIMO antennas with analog/digital beamforming, beam and carrier assignment, 3D/4D imaging, and simultaneous communication and radar for next generation radar systems.

The present disclosure provides sub-band coded OFDM for high-resolution radar.

In one embodiment, a sub-band or multi-band coded OFDM radar apparatus is provided. The sub-band or multi-band coded OFDM radar apparatus comprises: a set of antennas; an analog circuit; an analog-to-digital converter (ADC) and digital-to-analog converter (DAC); a digital circuit; a medium access control (MAC) controller; a processor operably connected to the set of antennas, the analog circuit, the digital circuit, and the MAC controller, the processor configured to; decompose wideband waveform signals into a time-frequency waveform based on a sequence of sub-band signals, generate a time-frequency radar waveform based on the decomposed wideband waveform signals, map, based on the time-frequency radar waveform, a constant amplitude zero auto-correlation (CAZAC) sequence into orthogonal frequency division multiplexing (OFDM) sub-carriers to generate a first radar signal. The sub-band or multi-band coded OFDM radar apparatus further comprises a transceiver operably connected to the processor, the transceiver configured to: transmit, to a target object via a transmit antenna of the set of antennas, the first radar signal; and receive, via a receive antenna of the set of antennas, a second signal that is reflected or backscattered from the target object. The processor is further configured to: determine each of the sub-band signals based on the first radar signal and the second signal; obtain a third signal by processing each of the sub-band signals in a frequency domain; aggregate each of the sub-band signals based on the third signals; and generate a correlation output in a time domain based on each of the aggregated sub-band signals.

In another embodiment, a method of a sub-band or multi-band coded OFDM radar apparatus is provided. The method comprises: decomposing wideband waveform signals into a time-frequency waveform based on a sequence of sub-band signals; generating a time-frequency radar waveform based on the decomposed wideband waveform signals; mapping, based on the time-frequency radar waveform, a constant amplitude zero auto-correlation (CAZAC) sequence into orthogonal frequency division multiplexing (OFDM) sub-carriers to generate a first radar signal; transmitting, to a target object via a transmit antenna of a set of antennas, the first radar signal; and receiving, via a receive antenna of the set of antennas, a second signal that is reflected or backscattered from the target object, determining each of the sub-band signals based on the first radar signal and the second signal; obtaining a third signal by processing each of the sub-band signals in a frequency domain; aggregating each of the sub-band signals based on the third signals; and generating a correlation output in a time domain based on each of the aggregated sub-band signals.

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> 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.

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.

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>. 11a/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 FIGURES <NUM>, <NUM>, and <NUM> 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.

In one example, power consumption is considered. Power consumption analysis of state-of-art mmWave OFDM system is shown in <FIG>.

<FIG> illustrate an example power dissipation of mmWave transceiver per transmit and receive path <NUM> in accordance with the present disclosure. The embodiment of the power dissipation of mmWave transceiver per transmit and receive path <NUM> illustrated in <FIG> is for illustration only. <FIG> do not limit the scope of this disclosure to any particular implementation.

As illustrated in <FIG>, a 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 transceiver design.

In one embodiment, a sub-channel coded OFDM with aggregation retaining the performance benefits of the wideband OFDM system is provided, while reducing the complexity associated with wide bandwidth signal, with low-power PA.

Compared with FMCW or chirp-sequence radars, a sub-channel phase-coded OFDM system with aggregation includes the following performance advantage: unlike FMCW system range-Doppler ambiguity, the sub-channel phase-coded OFDM system with aggregation can independently estimate range and Doppler; interference suppression by sequence coding; no need to generate highly linear frequency sweep in FMCW by analog circuitry; fast frequency ramp compared with FMCW; multiple sub-channels can be realized in time or frequency, allowing flexible design tradeoff between hardware complexity and acquisition time; flexible MIMO/beamforming design; and massive MIMO/BF gain allows systems with low-power PA, resulting in low-cost, scalable implementation with a complementary metal-oxide-semiconductor (CMOS) design that can be integrated with baseband circuitry.

<FIG> illustrates an example CAZAC sequence format <NUM> in accordance with the present disclosure. The embodiment of the CAZAC sequence format <NUM> illustrated in <FIG> is for illustration only. <FIG> does not limit the scope of this disclosure to any particular implementation.

In one embodiment, the CAZAC sequence format <NUM> may be used by a transmitter that is an electronic device. In one embodiment, the electron device may be a base station (e.g., <NUM>-<NUM> as illustrated in <FIG>) or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>).

As illustrated in <FIG>, the signal structure may be a reference signal. A reference signal is composed of cyclic prefix (CP), CAZAC sequence, and guard time (GT). The GT is added depending on the required sequence length, and the range of interest for the target scene. As illustrated in <FIG>, in a Format <NUM>, only one sequence period is shown. When targeting longer range, or in operations involving inclement weather conditions, where high signal degradation is expected, repeated sequence may be used such as Formats <NUM> and <NUM> as illustrated in <FIG>. With the Format <NUM>, the SINR at the receiver may be doubled, while in the Format <NUM>, the SINR is quadrupled. The time unit occupied by the reference signal is called "slot.

A polyphase sequence is generated from Zadoff-Chu sequences with a zero-correlation zone, generated from one or several root Zadoff-Chu sequences. Each radar unit is configured with a set of sequences that is allowed to use. For example, there are up to two sets of <NUM> sequences available in a root sequence. Each radar unit randomly chooses the sequence from the set at the time of transmission. Sequence hopping may be used to randomize the interference. A Zadoff-Chu sequence or binary sequences such as m-sequence can be used. Zadoff-Chu sequence is ideally suited for OFDM design due to constant envelope property of the signal in both frequency and time domains.

The uth root Zadoff-Chu sequence is defined by: <MAT>, <NUM>≤n≤NZC - <NUM> where the length NZC of the Zadoff-Chu sequence is given by TABLE <NUM>.

From the uth root Zadoff-Chu sequence, the polyphase sequence with zero correlation zones of length NCS - <NUM> is defined by cyclic shifts according to xu,v(n) = xu((n + Cv ) mod NZC ).

The parameter Ncs value is selected from the set described in TABLE <NUM>.

A coded OFDM signal is constructed by encoding each sub-carrier with the polyphase sequence, which is Zadoff-Chu CAZAC sequence in the present disclosure. Each coded OFDM signal occupies time-frequency resource called slot and sub-channel. Each time-frequency resource can be interpreted as a sub-band. In each sub-band, the same or mutually orthogonal CAZAC sequences may be used. Other sequences such as Generalized Chirp-Like (GCL) sequence may be used to generate a set of CAZAC sequences.

Multi-channel coded OFDM signal is generated by sending the reference signal in multiple carriers. For a <NUM> automotive radar with <NUM> bandwidth, the channel may comprise <NUM> sub-channels (e.g., carriers) starting from <NUM> as a center frequency and separated by <NUM> spacing. The carrier bandwidth may be <NUM>/<NUM>/<NUM>/<NUM>, resulting in <NUM>/<NUM>/<NUM>/<NUM> sub-channels, comprising a <NUM> wideband signal. Transmission works simultaneously for all channels.

<FIG> illustrates an example <NUM>-channel coded OFDM <NUM> in accordance with the present disclosure. The embodiment of the <NUM>-channel coded OFDM <NUM> illustrated in <FIG> is for illustration only. <FIG> does not limit the scope of this disclosure to any particular implementation.

In one embodiment, the <NUM>-channel coded OFDM <NUM> may be used by a transmitter that is an electronic device. In one embodiment, the electron device may be a base station (e.g., <NUM>-<NUM> as illustrated in <FIG>) or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>).

In one embodiment, a sub-set of multiple channels may be transmitted at a time. Illustration of multi-channel coded OFDM signal is shown in <FIG>. A sub-channel coded OFDM signal is generated by sending the reference signal at different sub-channels sequentially in time. The sub-channels may be generated sequentially or randomly by frequency hopping. Illustration of sub-channel coded OFDM signal is shown in <FIG>.

<FIG> illustrates an example sub-channel coded OFDM with uniform stepped carrier frequency <NUM> in accordance with the present disclosure. The embodiment of the sub-channel coded OFDM with uniform stepped carrier frequency <NUM> illustrated in <FIG> is for illustration only. <FIG> does not limit the scope of this disclosure to any particular implementation.

In one embodiment, the sub-channel coded OFDM with uniform stepped carrier frequency <NUM> may be used by a transmitter that is an electronic device. In one embodiment, the electron device may be a base station (e.g., <NUM>-<NUM> as illustrated in <FIG>) or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>).

<FIG> illustrates an example sub-channel coded OFDM with carrier frequency hopping <NUM> in accordance with the present disclosure. The embodiment of the sub-channel coded OFDM with carrier frequency hopping <NUM> illustrated in <FIG> is for illustration only. <FIG> does not limit the scope of this disclosure to any particular implementation.

In one embodiment, the sub-channel coded OFDM with carrier frequency hopping <NUM> may be used by a transmitter that is an electronic device. In one embodiment, the electron device may be a base station (e.g., <NUM>-<NUM> as illustrated in <FIG>) or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>).

<FIG> illustrates an example spectrum of multi-channel coded OFDM (<NUM>-channel case) <NUM> in accordance with the present disclosure. The embodiment of the spectrum of multi-channel coded OFDM (<NUM>-channel case) <NUM> illustrated in <FIG> is for illustration only. <FIG> does not limit the scope of this disclosure to any particular implementation.

Spectrum of constructed wideband signal is shown in <FIG>. For a multi-channel or a sub-channel OFDM signal, a signal is converted to a narrow band signal at the receiver and goes through a narrow-band (sub-band) signal processing for each path. Correlation and coherent accumulation of the resulting statistics generates statistic equivalent to wideband signal.

RADAR MAC controller is an entity assigning time-frequency resource and the code of the reference signal. Time-frequency resources are configured based on a targeted range, a transmit power, a beamforming method, and/or an interference level measured at a receiver. The frequency and the code resource hop between multiple sequences and frequency sub-bands randomly. The resource can be reassigned semi-statically or dynamically real-time during operation.

<FIG> illustrates an example transmitter architecture for multi-channel coded OFDM system <NUM> in accordance with the present disclosure.

In one embodiment, the transmitter architecture for multi-channel coded OFDM system <NUM> may be implemented at a base station (e.g., <NUM>-<NUM> as illustrated in <FIG>) or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>). The embodiments in <NUM> generates transmit signal composed of multiple sub-band channels modulating carriers f<NUM>,. A CZAC sequence <NUM> generates a sub-band CAZAC sequence by DFT pre-coding of a Zadoff-Chu sequence. An S/P <NUM> converts the serial data to parallel stream. An IFFT <NUM> takes the parallel pre-coded CAZAC sequence and converts the parallel stream of pre-coded CAZAC sequence to time-domain signal. A P/S and cyclic prefix <NUM> converts the time domain signal to serial stream and adds cyclic-prefix. Optional guard time is added. IF/DACs <NUM> and <NUM> take the in-phase and quadrature components of the output of <NUM> and converts them to analog data in-phase and quadrature signal. A phase shift <NUM> takes the output in-phase and quadrature analog signals of the outputs of <NUM> and <NUM> and modulates the carrier frequency. In block shaping filter and Amp <NUM>, the modulated carrier is further processed by a shaping filter and amplified and sent to the antenna(s). A MAC controller <NUM> configures and assigns time-frequency and code resources of the transmitter.

As illustrated in <FIG>, the circuit <NUM> includes all components such as <NUM>-<NUM> and circuits <NUM> and <NUM> may includes the same components as included in the circuit <NUM>. In one embodiment, additional circuit may be added into the transmitter architecture for multi-channel coded OFDM system <NUM>.

As illustrated in <FIG> of the transmitter, the analog circuit receives the output of the DAC, modulates the carrier, amplifies and filters the signal and feeds the signal to the antenna. As illustrated in <FIG> of the receiver, the analog circuit receives the signal from the antenna, filters and amplifies the signal, demodulates the carrier to baseband and sends it to ADC. The DAC converts the digital baseband signal to analog signal. The analog circuit may implement analog beamforming for multiple antennas by combining power amplifier (PA), filters and phase shifters. The ADC converts the analog signal to digital signal. The digital circuit in the transmitter generates digital waveform by baseband processing algorithm from sequences and symbol modulation and multiplexing. The digital circuit in the receiver processes the baseband signal and generates output signal such as decision statistic.

<FIG> illustrates an example transmitter architecture for sub-channel coded OFDM system <NUM> in accordance with the present disclosure. As illustrated in <FIG>, the transmitter architecture for sub-channel coded OFDM system <NUM> generates transmit sub-band channel signals modulating carriers f<NUM>,. The sub-band signal is generated sequentially in time. A CAZAC sequence <NUM> generates a sub-band CAZAC sequence by DFT pre-coding of a Zadoff-Chu sequence. An S/P <NUM> converts the serial data to parallel stream. An IFFT <NUM> takes the parallel pre-coded CAZAC sequence and converts the parallel stream of pre-coded CAZAC sequence to time-domain signal. A P/S and cyclic prefix <NUM> converts the time domain signal to serial stream and adds cyclic-prefix. An optional guard time is added. IF/DACs <NUM> and <NUM> take in-phase and quadrature components of the output of <NUM> and converts them to analog data in-phase and quadrature signal. A phase shift <NUM> takes the output in-phase and quadrature analog signals of the outputs of <NUM> and <NUM>, and modulates the carrier frequency. In a shaping filter and amp <NUM>, the modulated carrier is further processed by shaping filter, and amplified and send to the antenna. A MAC controller <NUM> configures and assigns time-frequency and code resources of the transmitter.

In one embodiment, the transmitter architecture for sub-channel coded OFDM system <NUM> may be implemented at a base station (e.g., <NUM>-<NUM> as illustrated in <FIG>) or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>).

A transmitter architecture for a sub-band coded OFDM system is shown in <FIG> and <FIG>. In a multi-channel coded OFDM system, multiple instances of transmit chain are implemented and processed in parallel. In a sub-channel coded OFDM system, a coded sub-band OFDM signal is modulated with a carrier frequency corresponding to a sub-channel for each slot.

<FIG> illustrates an example receiver architecture for multi-channel coded OFDM radar system <NUM> in accordance with the present disclosure.

In one embodiment, the receiver architecture for multi-channel coded OFDM radar system <NUM> may be implemented at a base station (e.g., <NUM>-<NUM> as illustrated in <FIG>) or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>).

A receiver architecture for a sub-band coded OFDM system is shown in <FIG>. For each sub-band, a signal is demodulated followed by a sub-band ADC. After CP removal, a correlation is computed in a frequency domain, by taking a fast Fourier transform (FFT) of a baseband signal, multiplication with the complex conjugate of the reference signal, followed by an inverse fast Fourier transform (IFFT).

A correlation value is interpolated by up-sampling followed by a low pass filet (LPF). Each processed sub-band signal is added. Detection statistic is formed by taking the amplitude or amplitude square, followed by a constant false alarm rate (CFAR) detector. A post-processing is achieved to remove the artefacts. Also, the correlation output is stored in a memory for Doppler estimation.

In a multi-channel coded OFDM system, multiple instances of a receiver chain are implemented and processed in parallel. In a sub-channel coded OFDM system, each sub-channel output is accumulated over time for detection and post-processing.

As illustrated in <FIG>, a phase shift <NUM> and ADC S/P and CP removal <NUM> describe sub-band signal processing. The phase shift <NUM>, received signal from the antenna is demodulated to generate in-phase and quadrature components of the analog signal. In ADC S/P and CP removal <NUM>, the analog signal is converted to digital signal by ADC, converted to parallel stream by serial-to-parallel (S/P) converter, and cyclic-prefix is removed. In FFT <NUM>, the output of <NUM> is further converted to frequency domain signal by FFT. In complex multiplication <NUM>, output signal of the IFT <NUM> is multiplied by complex conjugate <NUM> of the transmitted reference signal <NUM>. In IFFT <NUM>, the output of the complex multiplication1108 is converted to time-domain signal by IFFT. The signal is upsampled in an up-sampling <NUM> and filtered in a filter <NUM>.

The embodiment <NUM> takes amplitude or amplitude square. The embodiment <NUM> applies threshold according to CFAR criterion for detection of the result.

The embodiment <NUM> stores the combiner output in memory over multiple symbols. The embodiment <NUM> processes stored symbols and estimates Doppler.

In <NUM>, the detected result and Doppler processed signal is further processed in post processing.

In one embodiment, the combiner <NUM> combines the output signals of <NUM> in the circuit <NUM> with the output signals of circuit <NUM> and <NUM> in order to generate a wideband correlation output. The circuit <NUM> and <NUM> may include the same or similar component of the circuit <NUM> including <NUM> to <NUM>.

In one embodiment, an additional circuit or circuits may be added and combined with the output signals of the circuit <NUM>, <NUM>, and <NUM>.

A waveform for each sub-channel can be a filter-bank multi-carrier (FBMC) or a single-carrier (SC) without changing the overall architecture of the system. A sub-band OFDM signal can be a cyclic-prefix free signal.

A radar system can be built as a 3D radar for range, angle-of-arrival, and Doppler estimation or 4D imaging radar for Azimuth, elevation, range and Doppler images.

<FIG> illustrates an example hybrid beamforming architecture at the transmitter <NUM> in accordance with the present disclosure. The embodiment of the hybrid beamforming architecture at the transmitter <NUM> illustrated in <FIG> is for illustration only. <FIG> does not limit the scope of this disclosure to any particular implementation.

In one embodiment, the hybrid beamforming architecture at the transmitter <NUM> may be implemented at a base station (e.g., <NUM>-<NUM> as illustrated in <FIG>) or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>).

As illustrated in <FIG>, a digital beamforming is applied after IFFT, followed by an analog beamforming. In a multi-channel architecture, a digital beamforming is applied for each sub-band while analog beamforming is applied for the entire bandwidth, after combining multiple sub-bands. In a sub-channel architecture, both digital beamforming and analog beamforming may be applied for a sub-band. Receiver processing is applied per band and per antenna path.

As illustrated in <FIG>, in sequence generation and modulation <NUM>, one or multiple MIMO sequences are generated from CAZAC sequence. In a layer mapping <NUM>, the sequences are mapped to MIMO layers. In sub-band precoding <NUM>, each layer of the MIMO coding is applied to the MIMO layer sub-band signals with a Walsh-Hadamard code or a DFT code. In RE mappings <NUM> and <NUM>, the sequences are mapped to frequency domain by resource element (RE) mapping for each of the MIMO layers. In IFFT/CPs <NUM> and <NUM>, the RE mapped signal for each MIMO layer is transformed to time-domain by IFFT and cyclic prefix is added to the domain signal. A digital BF <NUM> performs digital beamforming by applying time-domain beamforming weights to the time-domain signal. In an IF/DAC <NUM>, the output of <NUM> is converted to analog signal by IF and ADC. In a combiner and analog BF <NUM>, the output signals of <NUM> of the circuit <NUM> is combined with the output signals of circuit <NUM> and <NUM>. The circuit <NUM> and <NUM> may include the same or similar component of the circuit <NUM> including <NUM> to <NUM>. In one embodiment, and further processed with analog beamformer.

In one embodiment, additional circuit may be added and combined with the output signals of the circuit <NUM>, <NUM>, and <NUM>.

In one embodiment, the hybrid beamforming architecture at the transmitter <NUM> further processes with analog beamforming.

As illustrated in <FIG>, beam (spatial), a sub-band (frequency), and a slot (time) can be selected independently, resulting in improvement in an acquisition time while avoiding interference.

<FIG> illustrates a flow chart of a method <NUM> for sub-band coded OFDM for high-resolution radar in accordance with the present disclosure, as may be performed by an advanced radio apparatus (e.g., <NUM>-<NUM> as illustrated in <FIG>) or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>).

In one embodiment, the method <NUM> may be performed by a stand-alone radar system that is implemented at a vehicle, a portable electronic device, a fixed electronic device, and any type of electronic devices.

As shown in <FIG>, the method <NUM> begins at step <NUM>.

In step <NUM>, the advanced radar apparatus decomposes wideband waveform signals into a time-frequency waveform based on a sequence of sub-band signals.

In one embodiment, the time-frequency radar waveform is an OFDM, a filter bank multi-carrier (FBMC), or a DFT pre-coded single carrier waveform.

Subsequently, in step <NUM>, the advanced radar apparatus generates a time-frequency radar waveform based on the decomposed wideband waveform signals;.

Subsequently, in step <NUM>, the advanced radar apparatus maps, based on the time-frequency radar waveform, a constant amplitude zero auto-correlation (CAZAC) sequence into orthogonal frequency division multiplexing (OFDM) sub-carriers to generate a first radar signal;.

Next, in step <NUM>, the advanced radar apparatus transmits, to a target object via a transmit antenna of a set of antennas, the first radar signal.

Finally, in step <NUM>, the advanced radar apparatus receives, via a receive antenna of the set of antennas, a second signal that is reflected or backscattered from the target object.

In some embodiments, various functions described in the present disclosure are implemented or supported by a computer program that is formed from computer readable program code and that is embodied in a computer readable medium.

Claim 1:
A sub-band or multi-band coded OFDM radar apparatus (<NUM>), comprising:
a set of antennas (<NUM>);
an analog circuit (<NUM>);
a digital circuit (<NUM>);
a medium access control (MAC) controller (<NUM>, <NUM>);
a processor (<NUM>) operably connected to the set of antennas (<NUM>), the analog circuit (<NUM>), the digital circuit (<NUM>), and the MAC controller (<NUM>, <NUM>), the processor (<NUM>) configured to:
decompose wideband waveform signals into a time-frequency waveform (<NUM>) based on a sequence of sub-band signals;
generate a time-frequency radar waveform (<NUM>) based on the decomposed wideband waveform signals;
map, based on the time-frequency radar waveform, a constant amplitude zero auto-correlation (CAZAC) sequence into orthogonal frequency division multiplexing (OFDM) sub-carriers (<NUM>) to generate a first radar signal; and
a transceiver (<NUM>, <NUM>) operably connected to the processor (<NUM>), the transceiver (<NUM>, <NUM>) configured to:
transmit, to a target object via a transmit antenna of the set of antennas (<NUM>), the first radar signal (<NUM>); and
receive, via a receive antenna of the set of antennas (<NUM>), a second signal (<NUM>) that is reflected or backscattered from the target object;
wherein the processor is further configured to:
determine each of the sub-band signals based on the first radar signal and the second signal;
obtain a third signal by processing each of the sub-band signals in a frequency domain;
aggregate each of the sub-band signals based on the third signals; and
generate a correlation output in a time domain based on each of the aggregated sub-band signals.