Patent Description:
Radars based on digital and/or analog waveforms and a signal processing are emerging in commercial high-resolution sensing applications. Numerous technologies break-through occurred, for example frequency modulated continuous-wave (FMCW) radar, chirp radar, and synthetic aperture radar. They have been used in mission-critical applications in military and space for surveillance and/or navigation. An example of such technologies is provided in <CIT>, which describes an advanced communication system implementing 3D imaging by means of coherent detection.

From the <NUM>'s, mobile communication technologies saw break-through, resulting in ubiquitous mobile communication coverage and the availability of low-cost mobile devices connecting people in the world. As emerging with <NUM>th generation (<NUM>) systems connecting the world, a major paradigm shift is occurring in a communication system. The most important change is connectivity for all things mobile. This in turn will enable automation foreseen by "Industry <NUM>" by analyzing massive amount of data generated by "intelligent" sensors, wideband, low-latency <NUM> connectivity, edge computing, and the management software located in an enterprise data center.

This disclosure provides systems and methods to produce a time-frequency spread waveform transmission and reception for a high-resolution digital radar system.

In one embodiment, an apparatus of an advanced wireless system is provided, the apparatus comprises a radar circuit including a set of antennas for transmission and reception, a transmitter, a receiver, and a medium access control (MAC) controller. The apparatus further comprises a controller operably connected to the radar circuit, the controller configured to: identify a discrete Fourier transform (DFT) of a long constant amplitude zero autocorrelation (CAZAC) sequence including multiple segments, identify, via the MAC controller, time-frequency resources for the multiple segments, identify a set of time-frequency sub-channels in the time-frequency resources, and sequentially map each of the multiple segments to each of the set of time-frequency sub-channels. The radar circuit is configured to transmit, via the transmitter, a first signal based on the set of time-frequency sub-channels.

In another embodiment, a method of an apparatus of an advanced wireless system is provided. The method comprises: identifying a DFT of a long CAZAC sequence including multiple segments; identifying time-frequency resources for the multiple segments; identifying a set of time-frequency sub-channels in the time-frequency resources; sequentially mapping each of the multiple segments to each of the set of time-frequency sub-channels; and transmitting a first signal based on the set of time-frequency sub-channels.

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 invention in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that the principles of the present invention 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. <FIG> may employ radar technologies including a digital radar, an analog radar, or a hybrid radar, or their related functionalities or operations. 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 g NodeB (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>. 11la/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.

As illustrated in FIGUIRE <NUM>, the gNB <NUM>, <NUM>, and <NUM> may employ a radar system, as shown in <FIG> and <FIG>, as one of communication parts (e.g., circuit, module, interface, function etc.) according to embodiment of the present disclosure. In addition, the UE <NUM> to <NUM> may employ a radar system including a digital radar system, an analog radar system, or a hybrid radar system, as shown in <FIG>, <FIG>, <FIG>, and <FIG>, as one of communication parts (e.g., circuit, module, interface, function etc.) according to embodiment of the present disclosure.

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 RF transceivers 210a-210n downconvert the incoming RF signals to generate IF or baseband signals. 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.

As illustrated in <FIG>, the gNB <NUM> may include a radar system as illustrated in <FIG>, <FIG>, <FIG>, and <FIG>. The controller <NUM> may include <NUM>, <NUM> as illustrated in <FIG> to control the radar <NUM>, or controller <NUM>, <NUM> as illustrated in <FIG> (as also illustrated in a transmitter <NUM> of <FIG>, and receivers of <FIG> and <FIG>). The radar (e.g., digital radar) <NUM> of <FIG> may be implemented independently and/or coexist with the controller <NUM> as illustrated in <FIG> and/or the processor <NUM> as illustrated in <FIG>, in order to control the radar <NUM> as illustrated in <FIG> and the transmitter <NUM> as illustrated in <FIG> and the receivers <NUM> as illustrated in <FIG>, and <NUM> as illustrated in <FIG>.

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).

As illustrated in <FIG>, the UE <NUM> may include a radar system as illustrated in <FIG>, <FIG>, <FIG>, and <FIG>. The processor <NUM> may be configured to control the radar system as illustrated in <FIG>, <FIG>, <FIG>, and <FIG>.

As illustrated in <FIG>, the UE <NUM> may include a radar system as illustrated in <FIG>, <FIG>, <FIG>, and <FIG>. The processor <NUM> may include <NUM>, <NUM> as illustrated in <FIG> to control the radar <NUM>, or controller <NUM>, <NUM> as illustrated in <FIG> (as also illustrated in a transmitter <NUM> of <FIG>, and receivers <NUM>, <NUM> of <FIG> and <FIG>). The radar (e.g., digital radar) <NUM> of <FIG> may be implemented independently and/or coexist with the controller <NUM> as illustrated in <FIG> and/or the processor <NUM> as illustrated in <FIG>, in order to control the radar <NUM> as illustrated in <FIG> and the transmitter <NUM> as illustrated in <FIG> and the receivers <NUM> as illustrated in <FIG>, and <NUM> as illustrated in <FIG>.

Sensors, in particular radar and Lidar are becoming an integral part of any automation, including automotive safety advanced driver assistance system (ADAS) systems and autonomous vehicle (AV) systems, perimeter security, <NUM> smart city, intelligent transportation systems, robotics, a remote surgery, and a smart factory. These sensors provide high-resolution and high-performance sensing such as <NUM>-dimensional (3D) images for computer vision. These sensors may provide massive amounts of real-time data and intelligent, providing insights analyzed by machine learning software located at the edge of the network. High-resolution imaging radars are becoming essential for machine perception in all environmental conditions, such as outdoor harsh environment.

A digital radar waveform brings performance that was not imaginable with an analog waveform in machine perception. The waveform is shaped to provide a low sidelobe level, a sharp range, Doppler resolution, and co-channel interference immunity from other radar users and intentional jamming signal.

Major challenge in a high-resolution radar waveform is its implementation complexity. In a frequency-modulated continuous wave (FMCW) radar, a stretch processing is an innovative way to reduce processing bandwidth of the signal. The resolution of range processing is determined by the bandwidth of the signal, which can be multi-GHz. In practical systems, the digital processing is limited by the sampling rate of the analog-to-digital converters (ADCs).

Phase modulation (PM) radars and orthogonal frequency division multiplexing (OFDM) radars based on a wide bandwidth signal would require a wideband and high bit-rate ADC. For high-resolution imaging radars, many RF channels are required, driving the cost and power consumption of the system. Furthermore, a digital signal processing would need to be done at Nyquist rate of the signal, making the receiver processing challenging, even in today's computation technology. OFDM signal generation and processing are 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 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 not practical. As such, commercially available radar transceivers rely on FMCW signal.

In the present disclosure, a novel radar with time-frequency waveform design is provided. The waveform is designed in a time and frequency domain allowing narrowband processing of digital waveform segments, reducing the burden on analog-to-digital convert/digital-to-analog convert (ADC/DAC) and the baseband processing requirement. The time-frequency waveform enables narrowband processing for a digital waveform with ADC and receiver processing at a slower speed that is feasible with today's technology. This architecture enables use of digital waveform for large bandwidth applications such as <NUM> sensing and imaging radar or emerging tera Hertz sensing and imaging applications.

In the context of coded OFDM radar, the provided waveform preserves the resolution and large processing gain of long sequence. The effect is in a sense similar to stretch processing in analog FMCW radar. A time-frequency waveform design in the present disclosure allows flexible coding, retaining the processing gain of the original wideband signal, without range limitations of conventional analog stretch processing.

The present disclosure provides a time-frequency waveform design, efficient digital transmission, and receiver processing. In the present disclosure, a time-frequency coded waveform with aggregation is provided. The time-frequency coded waveform retains the performance benefits of the wideband signal, while reducing the complexity associated with wide bandwidth signal by processing the signal in parallel at low rate and aggregating the processed signal.

The implementation uses successive transmission of narrow bandwidth in stretched time and processing of the narrow bandwidth signals in parallel to recover high resolution range and Doppler reconstruction of the radar signal. The present disclosure comprises some functions and operation blocks. In one example, the present disclosure comprises a time-frequency waveform design, transmission, and reception. In such example, a coded OFDM signal design and transmission in time-frequency resource is provided, for example, signal coding with long and short sequences for varying processing gain sequence is provided and frequency hopping to randomize interference is provided.

In one example, the present disclosure comprises: a receiver processing of sub-channel signal; a processing for normal range and extended range; a time-frequency waveform design and aggregation for contiguous and non-contiguous frequency bands with un-equal bandwidth; a scheduling and configuration of the radar signal in dedicated carriers; and scheduling and configuration of the radar signal in communication system such as <NUM>/<NUM>/<NUM> and WiFi/WiGig systems.

A time-frequency waveform with aggregation solves the implementation challenge of digital radars: (<NUM>) reducing transceiver complexity by reducing DAC/ADC bandwidth and bit width, sampling rate and receiver processing complexity, while retaining the high-resolution of the wide bandwidth signal by coherently processing sub-channels; (<NUM>) obtaining processing gain corresponding to the original long sequence is obtained by aggregating sub-channels; (<NUM>) scaling to very large bandwidth signal such as in Tera Hz and Lidars by processing of narrow bandwidth signals and achieving high resolution by aggregating sub-channels; and (<NUM>) processing a time-frequency waveform that is applicable to contiguous band or non-contiguous spectrum allocation and non-consecutive OFDM symbols for embedding digital radar signals in existing communication spectrum (e.g., in <NUM> band, <NUM>~<NUM> spectrum is divided into <NUM> spectrum chunks).

The time-frequency waveform with aggregation would allow range resolution up to <NUM> by aggregating the available spectrum. A linear FMCW/chirp signal spanning <NUM> bandwidth would not fit in <NUM> spectrum grid, limiting the achievable resolution <NUM>.

The time-frequency waveform design enables avoidance and cancellation of narrowband interference and jamming by processing sub-band signals; and received signal from multiple sub-bands can be combined flexibly, depending on the targeted range resolution and operation environments. The signal can be coherently combined for an increased processing gain or non-coherently combined for diversity and robustness.

A sequence is generated from a CAZAC sequence such as Zadoff-Chu or generalized chirp-like (GCL) sequences with a zero-correlation zone, generated from one or several root Zadoff-Chu or GCL sequences. The sequence can be either directly mapped to OFDM symbols or transformed by DFT before mapping to OFDM symbols.

Time-frequency OFDM signal is constructed by encoding each sub-carrier with a CAZAC sequence symbol. DFT of CAZAC sequence is mapped to time-frequency domain. Each coded OFDM signal occupies time-frequency resource, comprising multiple OFDM symbols and multiple frequency resources. Each time-frequency resource may be a "sub-channel.

In the present disclosure, the method and apparatus provide: 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 according to configured contiguous or non-contiguous time-frequency resources; 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 and aggregating contiguous or non-contiguous time-frequency resources.

<FIG> illustrates an example time-frequency coded OFDM waveform for a long sequence <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency coded OFDM waveform for a long sequence <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates an example time-frequency waveform with sequential sequence mapping.

<FIG> illustrates an example time-frequency coded OFDM waveform for a long sequence <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency coded OFDM waveform for a long sequence <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates an example time-frequency waveform with frequency hopping.

<FIG>, and <FIG> illustrate time-frequency waveforms for OFDM radar signal with a long sequence. <FIG>, and <FIG> show time-frequency resources with <NUM> OFDM symbols and <NUM> sub-bands. In the present disclosure, a time-frequency resource may be a "time-frequency channel. " A sequence is divided into <NUM> segments for transmission within the time-frequency resource. The sub-bands may be contiguous frequency resources or non-contiguous frequency resources, where there is gap between frequency sub-bands.

<FIG> show coded OFDM waveforms with a sequential sequence mapping. A long CAZAC sequence CAZAC1 is mapped to the time-frequency resources. The CAZAC sequence CAZAC1 is divided into <NUM> segments denoted as CAZAC1-<NUM> to CAZAC1-<NUM>. The first segment of the selected CAZAC sequence CAZAC1-<NUM> is mapped to the first "sub-channel" of time-frequency resource. The second segment of the selected CAZAC sequence CAZAC1-<NUM> is mapped to the second "sub-channel" of time-frequency resource. Similar mapping is applied for the third and fourth sub-channels.

The ordering and mapping of CAZAC sequence segments may be changed within the same time-frequency resource. <FIG> shows a coded OFDM waveform with a frequency hopping. A long CAZAC sequence CAZAC1 is mapped to the time-frequency resources. The CAZAC sequence CAZAC1 is divided into <NUM> segments denoted as CAZAC1-<NUM> to CAZAC1-<NUM>. The first segment of the selected CAZAC sequence CAZAC1-<NUM> is mapped to the first "sub-channel" of time-frequency resource. The third segment of the selected CAZAC sequence CAZAC1-<NUM> is mapped to the second "sub-channel" of time-frequency resource. The second segment of the sequence CAZAC1-<NUM> is mapped to the third sub-channel. The fourth segment of the sequence CAZAC1-<NUM> is mapped to the fourth sub-channel. In the next time-frequency channel, the ordering of CAZAC sequences are changed randomly.

The carrier frequency is changed randomly within a time-frequency resource unit. A frequency hopping pattern in shown in <FIG>.

<FIG> illustrates an example time-frequency coded OFDM waveform for a short sequence <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency coded OFDM waveform for a short sequence <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates a time-frequency waveform with single sequence mapping.

<FIG> illustrates an example time-frequency coded OFDM waveform for a short sequence <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency coded OFDM waveform for a short sequence <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates a time-frequency waveform with sequential sequence mapping.

<FIG> illustrates an example time-frequency coded OFDM waveform for a short sequence <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency coded OFDM waveform for a short sequence <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates a sequence hopping.

<FIG> illustrates an example time-frequency coded OFDM waveform for a short sequence <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency coded OFDM waveform for a short sequence <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates a time-frequency waveform with frequency hopping.

<FIG>, <FIG>, <FIG>, and <FIG> illustrate examples time-frequency waveform for OFDM radar signal with a short sequence. <FIG>, <FIG>, <FIG>, and <FIG> show time-frequency resource with <NUM> OFDM symbols and <NUM> sub-bands. A short sequence is mapped to each sub-band for each carrier. In the example, <NUM> root sequences are used as the radar signal.

<FIG> shows a coded OFDM waveform with a single sequence mapping. A first CAZAC sequence CAZAC1 is mapped to the time-frequency resource for all OFDM symbols within a time frequency resources.

<FIG> shows a coded OFDM waveform with multiple sequence mappings. A first CAZAC sequence CAZAC1 is mapped to the first time-frequency resources. A second segment of the selected CAZAC sequence CAZAC2 is mapped to the second "sub-channel" of time-frequency resource. Similar mapping is applied for the third and fourth sub-channels. The sequence selection is configured by a MAC entity. In the special case, same sequence may be used for the entire time-frequency resource.

The ordering and mapping of CAZAC sequences may be changed within the same time-frequency resource. <FIG> shows a coded OFDM waveform with sequence hopping. The first CAZAC sequence CAZAC1 is mapped to the first "sub-channel" of time-frequency resource. The third CAZAC sequence CAZAC3 is mapped to the second "sub-channel" of time-frequency resource. The second CAZAC sequence CAZAC2 is mapped to the third Sub-Channel. The fourth CAZAC sequence CAZAC4 is mapped to the fourth Sub-Channel. In the next time-frequency channel, the ordering of CAZAC sequences are changed again randomly.

<FIG> illustrates an example transmitter for a time-frequency waveform <NUM> according to embodiments of the present disclosure. An embodiment of the transmitter for a time-frequency 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.

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

At each transmission interval, a CAZAC sequence is mapped into a frequency domain, for each carrier frequency. The signal is transformed to a time domain by IFFT, and cyclic-prefix (CP) and guard time (GT) are appended. The I/Q signal is converted to analog domain by DAC and modulated by a carrier frequency before transmission.

RADAR MAC is an entity assigning time-frequency resources of the reference signal. Time-frequency resources are configured based on a targeted range, a transmit power, a beamforming method, and a noise and interference measured at a receiver. The resources can be re-assigned semi-statically or dynamically real-time during operation. The time-frequency channel is configured by the configuration module in the controller. A CAZAC sequence is selected by MAC resource allocation. For each OFDM symbol, one carrier frequency is selected. At next time-frequency resource unit, the modulated symbol(s) modulates another carrier, making up a sub-channel.

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 CAZAC sequence <NUM> generates a sub-band CAZAC sequence by DFT pre-coding of a Zadoff-Chu or a GCL 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 signals. A phase shifter <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 amplifier (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 include the same components as included in the circuit <NUM>. In one embodiment, additional circuitry may be added into the transmitter architecture for multi-channel coded OFDM system <NUM>.

<FIG> illustrates an example time-domain signal format <NUM> according to embodiments of the present disclosure. An embodiment of the time-domain signal format <NUM> shown in <FIG> is for illustration only.

<FIG> shows the signal structure which may be interpreted to a reference signal. A reference signal is composed of cyclic-prefix (CP), a polyphase sequence, and a guard time (GT). The polyphase sequence is the OFDM waveform generated by taking the IFFT of the time-frequency signal. The GT is added based on a sequence length, and the range of interest for the target scene and the hardware settling time. In 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>.

<FIG> illustrates an example receiver for a time-frequency waveform <NUM> according to embodiments of the present disclosure. An embodiment of the receiver for a time-frequency 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 N sub-channels. For each sub-channel, received signal is down-converted and converted by ADC to digital baseband signal. After CP removal, the received signal is converted to frequency-domain sub-band signals. After OFDM symbol-level phase offset compensation and sub-band mapping to a wideband signal, a range correlation is computed in the frequency domain. This is achieved by multiplication with the complex conjugate of the reference signal. The reference signal is either a short CAZAC sequence or sequences, or in case of long sequence, segments of CAZAC sequences. These reference signals are the original frequency-domain sequences that were transmitted. The correlation output is stored in a memory for Doppler estimation.

In one embodiment, the receiver as illustrated in <FIG> may be implemented at a base station (e.g., <NUM>-<NUM> as illustrated in <FIG>) and/or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>).

Detection statistic is formed by taking the amplitude or amplitude square of the correlator output, followed by a CFAR detector, resulting in range and doppler estimates. Depending on targeted maximum range, one or multiple receiver processing chain may be instantiated.

As illustrated in <FIG>, a signal is processed at a <NUM> degree phase shift block <NUM>. An output of the <NUM> degree phase shift block <NUM> is transmitted to an ADC S/P and CP removal block <NUM>. An output of FFT N point block <NUM> is transmitted to a phase offset compensation according to the phase compensation factor ( <MAT>) and complex multiplication block <NUM>. An output of DFT and complex conjugate block <NUM> receiving a reference CAZAC sequences is transmitted to the phase offset compensation and complex multiplication block <NUM>. A buffer and sub-band mapping block <NUM> receives an output signal of the phase offset compensation and complex multiplication block <NUM> and transmits an output signal of the phase offset compensation and complex multiplication block <NUM> to IFFT 4N point block <NUM>. An output of IFFT 4N point block <NUM> is transmitted to block <NUM>. An output of block <NUM> is transmitted to a CFAR detector block <NUM> and memory <NUM>. The memory <NUM> transmits an output signal to the CFAR detector block <NUM> through a Doppler estimation block <NUM>.

By mapping the sequences or sequence segments, a wideband signal is reconstructed. <FIG> illustrates an example sub-band to wideband signal mapping <NUM> according to embodiments of the present disclosure. An embodiment of the sub-band to wideband signal mapping <NUM> shown in <FIG> is for illustration only. <FIG> shows the reconstructed wideband signal from multiple sub-band signal.

A conventional OFDM radar would be limited by the length of the signal. With a time-frequency waveform, range extension beyond the OFDM symbol length is achieved, by receiver processing without modification of transmit signal.

<FIG> illustrates an examples time-frequency waveform structure <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency waveform structure <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates an examples time-frequency waveform structure for a normal range.

<FIG> illustrates an examples time-frequency waveform structure <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency waveform structure <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates an examples time-frequency waveform structure for an extended range.

<FIG> shows the waveform for normal range. In case of normal range, the length of the guard time (GT) is set as the OFDM symbol duration. The maximum range is determined by the duration of the guard time. At the receiver, signal is received up to the GT and sub-channel multiplication is computed.

<FIG> shows the waveform for extended range where GT is twice the length of the OFDM symbol. Range is extended by a factor of two. In the receiver, a signal is received up to the extended guard time. In this example, a receiver processing is extended to <NUM> OFDM symbols.

In a <NUM>-subchannel time-frequency waveform, range extension up to factor of <NUM> is achieved without increasing the transmit signal time-frequency resource. For a radar signal design having <NUM> range, the range extension up to <NUM> is achieved by receiver implementation within the same time-frequency resource. Range beyond <NUM> is provided by configuring longer guard time.

<FIG> illustrates an example receiver with range extension <NUM> according to embodiments of the present disclosure. An embodiment of the receiver with range extension <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, the receiver architecture with range extension as illustrated inf <FIG> may be implemented at a base station (e.g., <NUM>-<NUM> as illustrated in <FIG>) and/or a UE (e.g., <NUM>-<NUM> as illustrated in <FIG>).

As illustrated in <FIG>, the receiver <NUM> includes two chains of blocks <NUM> and <NUM>. The block <NUM> includes a <NUM> degree phase shift block <NUM>, an ADC, S/P and CP removal block <NUM>, an FFT N point block <NUM>, a phase offset compensation according to the phase compensation factor ( <MAT>) and complex multiplication block <NUM>, and a DFT and complex conjugate block <NUM>. Similar to the block <NUM>, the block <NUM> includes a <NUM> degree phase shift block <NUM>, an ADC, S/P and CP removal block <NUM>, an FFT N point block <NUM>, a phase offset compensation and complex multiplication block <NUM>, and a DFT and complex conjugate block <NUM>. Output signals of block <NUM> and <NUM> are transmitted to buffer and sub-band mapping block <NUM>. The buffer and sub-band mapping block <NUM> transmit an output signal to an IFFT 4N point <NUM>. An output signal of the IFFT 4N point block <NUM> transmits an output signal to a block <NUM>. The block <NUM> transmits an output signal to a memory <NUM> and a CFAR detector block <NUM>. The memory <NUM> transmits an output signal to the CFAR detector block <NUM> through a Doppler estimation block <NUM>. Block diagram of the receiver for range extension generalized for N sub-channels is shown in <FIG>.

A first sub-channel receives and processes a signal for N OFDM symbol periods. Similarly, each receiver continues to receive and processes time-domain signal for N OFDM symbol periods. The entire signal is processed for N OFDM symbols and the peak value is computed, generating range profile for (N-<NUM>) OFDM symbol periods. This extends the range by a factor of (N-<NUM>). Hardware complexity of the receiver is increased from <NUM> for normal range to N for range extension.

Depending on spectrum allocation, the available spectrum for radar imaging may be non-contiguous. This arises in existing communication bands and unlicensed <NUM> spectrum, where a spectrum grid is divided into multiple chunks. For an automotive radar frequency in <NUM> to <NUM>, the contiguous spectrum is available. In a V-Band, spanning <NUM> to <NUM>, <NUM> bands each with <NUM> bandwidth is available with <NUM> frequency grids, with a gap between the sub-bands. A length of the sequences in each sub-channel does not need to be identical. As long as the aggregated bandwidth of the signal are the same, sub-channel bandwidth and the length of the sequence mapped to the sub-channel can be different without affecting the range resolution of the resulting image.

The time-frequency waveform mapping is described below for both contiguous and non-contiguous spectrum allocations.

<FIG> illustrates an examples time-frequency signal mapping <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency signal mapping <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates an example time-frequency signal mapping for contiguous sub-band mapping.

<FIG> illustrates an examples time-frequency signal mapping <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency signal mapping <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates an example time-frequency signal mapping for non-contiguous sub-band mapping.

<FIG> shows a time-frequency mapping for a contiguous spectrum, where the difference between the carriers is equal to the bandwidth of the sub-channel, i.e., Δf = f<NUM> - f<NUM> = BW. <FIG> shows a time-frequency mapping for a non-contiguous spectrum, where the difference between the carriers is larger than the bandwidth of the sub-channel, i.e., Δf = f<NUM> - f<NUM> > BW.

In one embodiment, for contiguous spectrum, range resolution corresponding to Nyquist sampling rate is obtained in the reconstructed signal.

In one embodiment, for non-contiguous spectrum, range resolution of the reconstructed signal is reduced due to the unused band between the sub-bands.

<FIG> illustrates an example time-frequency signal mapping with non-consecutive OFDM symbols <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency signal mapping with non-consecutive OFDM symbols <NUM> shown in <FIG> is for illustration only. Specifically, <FIG> illustrates an example of the time-frequency signal mapping with non-consecutive OFDM symbols for contiguous sub-band mapping.

<FIG> illustrates an example time-frequency signal mapping with non-consecutive OFDM symbols <NUM> according to embodiments of the present disclosure. An embodiment of the time-frequency signal mapping with non-consecutive OFDM symbols <NUM> shown in <FIG> is for illustration only. Specifically, FIGRE 13B illustrates an example of the time-frequency signal mapping with non-consecutive OFDM symbols for non-contiguous sub-band mapping.

As illustrated in <FIG>, not all OFDM symbols are used for radar signal transmission. <FIG> shows a time-frequency mapping for a contiguous spectrum, where Δf = f<NUM> - f<NUM>. <FIG> shows a time-frequency mapping for a non-contiguous spectrum, where the difference between the carriers is larger than the bandwidth of the sub-channel.

Range resolution of the signals as illustrated in <FIG>, and <FIG> are the same. A phase compensation factor corresponding to the OFDM symbol index is applied when computing the correlation in the receiver described in <FIG>.

<FIG> illustrates an example resolution of reconstructed signal <NUM> according to embodiments of the present disclosure. An embodiment of the example resolution of reconstructed signal <NUM> shown in <FIG> is for illustration only.

<FIG> shows the impact of spectrum mapping on the resolution of the signal. If the signal is reconstructed from a full bandwidth such as in contiguous sub-band mapping, a signal is reconstructed at Nyquist rate as illustrated in <FIG>.

A sample period is <MAT> where ABW is the aggregate bandwidth of the signal. For non-contiguous allocation, with the available bandwidth is smaller than the total bandwidth, signal resolution is reduced. Due to sub-Nyquist sampling, aliasing occurs in time (as such in range) domain as shown in <FIG>.

<FIG> illustrates an example radar and controller architecture <NUM> according to embodiments of the present disclosure. An embodiment of radar and controller 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 radar and controller architecture <NUM> includes a radar circuit <NUM> (e.g., digital radar) and a controller <NUM>. The digital radar <NUM> includes a Tx antenna DAC and RF <NUM>, an Rx antenna ADC and RF <NUM>, a transmitter <NUM>, a receiver <NUM>, and a MAC <NUM>. The controller <NUM> includes a MAC (controller) <NUM> and a configuration block <NUM>. The MAC (controller) <NUM> includes a power control <NUM>, a scheduler <NUM>, and interference management <NUM>. The configuration block <NUM> includes a signal configuration block <NUM>, a measurement configuration block <NUM>, and a power saving configuration block <NUM>. The Tx antenna DAC and RF <NUM> includes a set of antennas for transmission of signals and the Rx antenna ADC and RF <NUM> includes a set of antennas for reception of signals.

A controller has a configuration entity and a medium access control (MAC) entity. The configuration entity is responsible for setting signal configuration, measurement configuration, and power saving configurations. The MAC entity inside the controller is responsible for dynamically managing radio resources and comprises a power control function, a scheduler, and interference management circuits.

A scheduler in a MAC controller determines time-frequency resources and a sequence configuration.

As illustrated in <FIG>, in one example of Step <NUM>, device capability such as transmit power and maximum RF bandwidth is reported from the digital radar <NUM> to the controller <NUM>. In one example of Step <NUM>, a measurement configuration is sent from the controller <NUM> to the digital radar <NUM> for such as noise and interference measurements. In one example of Step <NUM>', a power control configuration is sent from the controller <NUM> to the digital radar <NUM>. In one example of Step <NUM>, a measurement result is reported from the digital radar <NUM> to the controller <NUM>. This may be periodic or aperiodic. In one example of Step <NUM>, a MAC configuration block and the scheduler sets a time-frequency channel, a sequence mapping, a long/short sequence selection, a sequence hopping and frequency hopping pattern, and MIMO and beamforming configurations.

In such example, the sequence and the time-frequency resource are determined as follows: the sequence may be fixed throughout the transmission interval; the selected sequence may be changed randomly for each time-frequency channel; and the selected sequence may be scheduled by "scheduler" entity in a radar MAC, depending on noise and interference estimation for each sub-channel. Based on the allocated radio resource, radar constructs the signal for transmission.

In <NUM>, <NUM>, or WiFi communication system, a scheduler allocates time-frequency resource for a radar signal transmission and reception. Alternatively, a configuration circuit determines the time-frequency resources for radar signal transmission.

<FIG> illustrates a flowchart of a method <NUM> for a time-frequency spread waveform for high-resolution digital radar according to embodiments of the present disclosure, as may be performed by a UE (e.g., <NUM>-<NUM>), a BS (e.g., <NUM>-<NUM>), or a stand-alone system, not installed on a UE or base station, such as an individual and independent radar system. An embodiment of 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>, an apparatus identifies a discrete Fourier transform (DFT) of a long constant amplitude zero autocorrelation (CAZAC) sequence including multiple segments.

Subsequently, the apparatus in step <NUM> identifies, via a MAC controller, time-frequency resources for the multiple segments.

Subsequently, the apparatus in step <NUM> identifies a set of time-frequency sub-channels in the time-frequency resources.

Next, the apparatus in step <NUM> sequentially maps each of the multiple segments to each of the set of time-frequency sub-channels.

Finally, the apparatus in step <NUM> transmits a first signal based on the set of time-frequency sub-channels.

In one embodiment, the apparatus performs a sequence hopping operation to randomly map each of the multiple segments to each of the set of time-frequency sub-channels and/or performs a frequency hopping operation to map each of the multiple segments to each of the set of time-frequency sub-channels that is randomly selected.

In one embodiment, the apparatus identifies a DFT of a set of short CAZAC sequences and identifies the time-frequency resources for the set of short CAZAC sequences, the time-frequency resources comprising contiguous time-frequency resources or non-contiguous time-frequency resources in a time-frequency domain.

In one embodiment, the apparatus identifies the set of time-frequency sub-channels in the time-frequency resources and sequentially maps each of the set of short CAZAC sequences to each of the set of time-frequency sub-channels.

In one embodiment, the apparatus performs a sequence hopping operation to randomly map each of the set of short CAZAC sequences to each of the set of time-frequency sub-channels and/or performs a frequency hopping operation to map each of the set of short CAZAC sequences to each of the set of time-frequency sub-channels that is randomly selected.

In one embodiment, the apparatus receives a second signal in one of multiple guard symbol periods, the second signal being a reflected signal of the first signal, performs a frequency domain conversion operation for the second signal, and performs a phase offset compensation operation for the frequency domain converted second signal, the phase offset compensation operation corresponding to the set of time-frequency sub-channels in a frequency domain.

In one embodiment, the apparatus performs the phase offset compensation operation for the second signal in a time domain before performing a fast Fourier transform (FFT) operation or during a computation operation of the FFT operation.

In such embodiments, the time-frequency resources comprise contiguous time-frequency resources and non-contiguous time-frequency resources in a time-frequency domain.

In such embodiments, radio resources are configured by a medium access control (MAC) controller for a transmitter to transmit the first signal.

Claim 1:
An apparatus of an advanced wireless system, the apparatus comprising:
a radar circuit including a set of antennas for transmission and reception, a transmitter, a receiver, and a medium access control, MAC, controller; and
a controller operably connected to the radar circuit, the controller configured to:
identify a discrete Fourier transform, DFT, of a long constant amplitude zero autocorrelation, CAZAC, sequence including multiple segments,
identify, via the MAC controller, time-frequency resources for the multiple segments,
identify a set of time-frequency sub-channels in the time-frequency resources, and
sequentially map each of the multiple segments to each of the set of time-frequency sub-channels,
wherein the radar circuit is configured to transmit, via the transmitter, a first signal based on the set of time-frequency sub-channels.