Reconfigurable multimode multiplexing sensing system

Abstract

The invention belongs to the technical field of wireless communication, and particularly relates to a reconfigurable multimode multiplexing sensing system which comprises a frequency synthesizer with a high-pass signal injection function, N transmitting channels, N receiving channels and an intermediate-frequency signal processing module, N is larger than or equal to 1, and the intermediate-frequency signal processing module is connected with the receiving channels and used for processing intermediate-frequency signals. The intermediate frequency signal processing module comprises a radar signal processing channel and a communication signal processing channel which are mutually independent; the system can be configured into a plurality of working modes, and the working modes at least comprise a communication sensing frequency division multiplexing mode, a communication sensing time division multiplexing mode, an independent communication working mode and an independent sensing working mode. The method for simultaneously realizing communication and radar signal generation by the single frequency synthesizer has the advantages of reconfigurability, high flexibility, high modulation rate and strong anti-interference performance, and the intermediate frequency signal processing method applied to communication and perception integration has the advantages of reconfigurability of signal bandwidth and high conversion rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to a reconfigurable multi-mode multiplexing sensing system. BACKGROUND

[0002] Integrated Sensing And Communication (ISAC) is a technology that deeply integrates communication and sensing functions, and its core goal is to achieve efficient coordination of communication and sensing through shared radio frequency signals, while ensuring the independence between communication and sensing (radar) signals, and having the general performance of advanced radar and communication systems. In recent years, with the rapid development of wireless communication technologies (such as 5G / 6G, Wifi, millimeter wave radar technology, etc.), ISAC technology has attracted widespread attention from academia and industry due to its efficient spectrum utilization and functional integration advantages.

[0003] In early related research, radar systems and communication systems were studied and designed as two independent systems, but in actual applications, many problems such as construction, budget, management, etc. will be encountered, and currently, with the miniaturization of integrated circuit processes, radar signal processing and communication signal processing hardware circuits and software algorithms are gradually approaching, so after that, integrating communication and sensing functions in the same system has become a research hotspot, i.e. Dual-Function Radar-Communication (DFRC) system, which can be divided into radar-centric design method and communication-centric design method according to application requirements. The radar-centric design method mainly introduces radar waveform modulation with different periods or low-speed Frequency-Shift Keying (FSK) or Phase-Shift Keying (PSK) into existing radar systems to modulate the periodic waveforms of Frequency modulation continuous wave (FMCW) or Pulse Radar, which results in extremely slow communication rate. At the same time, due to the fact that the transmit and receive channels need to be opened at the same time during the operation of some radar systems, especially continuous wave radar systems, this may cause a serious feedthrough phenomenon, resulting in a large direct current block in the intermediate frequency signal obtained after receiving and mixing, which limits the design of zero intermediate frequency communication systems in the radar-centric design method. On the other hand, the communication-centric design method has low radar sensing reliability due to the randomness of the communication waveform and the dependence of the radar signal on the corresponding communication signal.

[0004] Currently, to solve the problems encountered in the above research, the research on the integration of communication and sensing mainly focuses on determining the architecture of the communication and sensing integration system, that is, simultaneously achieving accurate sensing of the radar system and efficient communication of the communication system in a single radio frequency transceiver integrated radar and communication system. For example, a related patent (CN11345249B) of Southeast University proposes a single-station full-duplex communication and sensing integration signal design and processing method, which uses a radar signal modulated by slow-time coding for low-rate information transmission, and uses radar echo waiting time to send communication signals, thereby achieving a higher spectrum efficiency. However, the related research uses time division multiplexing technology, and the echo waiting time is still affected by the pulse radar waveform. Moreover, this communication and sensing integration scheme is only suitable for pulse radar systems and is not suitable for frequency-modulated continuous wave systems. Pulse radar is mainly used in long-range sensing, while frequency-modulated continuous wave has obvious advantages in short-range sensing. Therefore, the inability to adapt to frequency-modulated continuous wave radar systems results in a lack of advantages in short-range communication sensing for this patent. Another related patent (CN119828135A) of Kunshan Innovation Research Institute of Xi'an University of Electronic Science and Technology proposes a method of generating a communication waveform through a high-speed digital-analog converter (DAC), and then up-converting through a local oscillator to generate a communication signal. Another DAC is used as the input source of the local oscillator to generate a radar signal. Although this method can generate different communication and radar signals, it requires two intermediate frequency processing systems to process radar and communication signals during the up-conversion process, which makes the system complex. Moreover, using a DAC as the input source of the local oscillator will severely deteriorate the phase noise of the local oscillator, resulting in deterioration of the signal-to-noise ratio performance of the system.

[0005] In summary, the present application proposes a radar and communication signal modulation path close to each other, and a single frequency synthesizer is used to generate radar and communication signals. A multi-mode communication and sensing integrated transceiver system is also proposed, which supports functions such as frequency division multiplexing (FDM), time division multiplexing (TDM), radar mode, communication mode, etc. According to different application scenarios, the system can be configured to operate in the same frequency mode for communication and sensing, and the communication and sensing signals can be processed and separated using a zero intermediate frequency signal processing method at the receiving end. In addition, the system can also use a two-station / multi-station mode to network two or more transceiver systems. In the case of transceiver separation, the system can operate in different frequencies and synchronize the radar in real time according to the communication signal, thereby achieving high-speed non-zero intermediate frequency signal processing to suppress the direct current blocking problem caused by transceiver feedthrough in the radar system. SUMMARY

[0006] (I) Technical problems solved

[0007] In view of the deficiencies of the prior art, the present application provides a reconfigurable multi-mode multiplexing sensing system, which solves the problem that the existing scheme lacks a unified architecture capable of flexibly generating and processing communication and radar signals, and it is difficult to realize efficient communication sensing integration in a single system.

[0008] (II) Technical solutions

[0009] In order to achieve the above purpose, the present application specifically adopts the following technical solutions: a reconfigurable multi-mode multiplexing sensing system, comprising: a frequency synthesizer with high communication signal injection function, for generating radio frequency signals according to the working mode, to generate continuous frequency modulation wave superimposed on frequency control key shift modulation wave;

[0010] N transmitting channels, wherein N≥1, connected with the frequency synthesizer, for transmitting the radio frequency signals generated by the frequency synthesizer, the transmitting channels do not include an up-conversion module;

[0011] N receiving channels, wherein N≥1, for receiving radio frequency signals containing communication signals and / or radar sensing echo signals, and performing a down-conversion processing, to output intermediate frequency signals;

[0012] An intermediate frequency signal processing module connected with the receiving channel, for processing the intermediate frequency signals, the intermediate frequency signal processing module includes a radar signal processing path and a communication signal processing path which are independent of each other;

[0013] Wherein, the system can be configured in multiple working modes, the working modes at least include: communication sensing frequency division multiplexing mode, communication sensing time division multiplexing mode, communication working mode and sensing working mode.

[0014] Further, the frequency synthesizer comprises: a controlled oscillator;

[0015] A phase-locked loop (PLL) connected with the controlled oscillator, for providing frequency locking function;

[0016] A frequency modulator configured to generate radar modulation signals and communication modulation signals;

[0017] The output of the frequency modulator is connected to the control end of the controlled oscillator through at least one modulation path, so that the radar modulation signals and the communication modulation signals can directly modulate the output frequency of the controlled oscillator, realizing high communication signal injection.

[0018] Further, the radar modulation signals generated by the frequency modulator are used to generate frequency modulation continuous wave (FMCW) signals, and the communication modulation signals generated by the frequency modulator are used to generate frequency shift keying (FSK) signals;

[0019] The modulation path is equipped with a dedicated digital-to-analog converter (DAC) for the induction system. The digital modulation signal output by the frequency modulator is converted into an analog signal by the DAC and then injected into the controlled oscillator.

[0020] Furthermore, it also includes a digital-to-analog converter (DAC) calibration module for performing nonlinear calibration and / or signal mismatch calibration on the DAC, wherein the calibration method employs a lookup table-based digital predistortion LUT-DPD technique; when performing nonlinear calibration of the radar modulation signal, the DAC calibration module is configured to:

[0021] Disconnect the loop of the PLL;

[0022] Scan the DAC control word and use a phase frequency detector to detect the deviation between the output frequency of the controlled oscillator and the target frequency;

[0023] The weighted matrix is ​​iteratively updated based on the deviation until the deviation meets the predetermined norm requirement, and the final weighted matrix is ​​used as the calibration lookup table.

[0024] Furthermore, the generation of the communication modulation signal adopts frequency domain on / off keying (F-OOK) technology, which modulates the baseband binary data onto a high-frequency carrier, so that the spectrum of the communication signal is far away from the spectrum of the radar signal, thereby ensuring the independence between signals and the stability of the system.

[0025] Furthermore, the intermediate frequency signal output after downconversion by the receiving channel is a zero intermediate frequency signal or a non-zero intermediate frequency signal;

[0026] When the system is operating in single-station same-frequency transceiver mode, it is configured to operate in zero intermediate frequency signal mode;

[0027] When the system operates in multi-station networking mode, it is configured to operate in non-zero intermediate frequency signal mode, where there is a fixed difference between the carrier frequencies of the transmitting station and the receiving station, so that the center frequency of the intermediate frequency signal after down-conversion is far away from the DC region.

[0028] Furthermore, in the non-zero intermediate frequency signal operating mode, the system achieves clock and trigger synchronization between multiple radio frequency transceiver systems through communication signals.

[0029] Furthermore, the intermediate frequency signal processing module includes an ultra-high-speed analog-to-digital converter (ADC);

[0030] In zero-IF signal operating mode, the ADC employs noise shaping technology;

[0031] In the non-zero intermediate frequency signal operating mode, digital domain bandpass filtering technology is used to process the signal.

[0032] A reconfigurable multimodal multiplexing synesthesia method includes the following steps:

[0033] Mode configuration steps: Based on the application scenario, configure the system to any one of the following: communication sensing frequency division multiplexing, communication sensing time division multiplexing, communication working mode, or sensing working mode;

[0034] Signal generation steps: The required radar RF signal and / or communication RF signal are directly generated using a single-frequency synthesizer and high-pass signal injection technology.

[0035] Signal transmission steps: The radio frequency signal is transmitted through the transmission channel, which does not involve an up-conversion process;

[0036] Signal reception and down-conversion steps: Receive the signal through the receiving channel and perform a down-conversion to obtain the intermediate frequency signal;

[0037] Signal processing steps: The intermediate frequency signal is separated and processed by the intermediate frequency signal processing module to obtain the sensing target information and communication data respectively.

[0038] Furthermore, it also includes: achieving synchronization between the transmitting station and at least one receiving station through trigger information carried by the communication signal; and maintaining a fixed deviation between the carrier frequencies of the transmitting station and the receiving station to ensure that a non-zero intermediate frequency signal is obtained after downconversion at the receiving end.

[0039] (III) Beneficial Effects

[0040] Compared with the prior art, the present invention provides a reconfigurable multimode multiplexing sensing system, which has the following beneficial effects:

[0041] The method for simultaneously generating communication and radar signals using a single frequency synthesizer in this invention features reconfigurability, high flexibility, fast modulation rate, and strong anti-interference capabilities. The radar and communication DAC calibration scheme offers advantages such as low hardware cost, fast calibration speed, and high calibration accuracy. The scheme for generating communication signals in integrated sensing and communication using frequency domain on / off keying technology offers advantages such as not affecting the stability of the phase-locked loop, high communication rate, and strong anti-interference capabilities. The integrated communication and sensing multi-mode switching method offers advantages such as high flexibility and high adaptability to different application scenarios.

[0042] The non-frequency technology of multi-station transceiver systems in non-zero intermediate frequency mode and its trigger synchronization technology based on communication signals have the advantages of strong anti-interference, strong adaptability and high configuration flexibility; applied to the intermediate frequency signal processing method of communication and sensing integration, it has the advantages of reconfigurable signal bandwidth and high conversion rate. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the integrated inductive radio frequency transceiver system of the present invention;

[0044] Figure 2This is a schematic diagram of the four operating modes of the transmission channel end of the present invention;

[0045] Figure 3 This is a schematic diagram of two working modes of the receiving channel end of the present invention;

[0046] Figure 4 This is a schematic diagram of the frequency synthesizer with high-pass signal injection function of the present invention;

[0047] Figure 5 This is a schematic diagram of the high-pass signal injection technology of the present invention;

[0048] Figure 6 This is a schematic diagram illustrating the high-pass signal injection stability of the present invention;

[0049] Figure 7 The transfer function of the radar modulation signal to the phase difference in this invention is the Bode. Figure 1 Schematic diagram;

[0050] Figure 8 The transfer function of the communication modulation signal to the phase difference in this invention is the Baud rate. Figure 2 Schematic diagram;

[0051] Figure 9 This is a schematic diagram of the frequency domain on / off key control technology of the present invention;

[0052] Figure 10 This is a schematic diagram illustrating the effect of radar modulation signal nonlinearity on the system according to the present invention;

[0053] Figure 11 This is a schematic diagram illustrating the impact of communication modulation signal mismatch on the system according to the present invention;

[0054] Figure 12 This is a flowchart of the radar modulation signal calibration process of the present invention;

[0055] Figure 13 This is a flowchart of the communication modulation signal calibration process of the present invention;

[0056] Figure 14 This is a schematic diagram of the process method of the present invention. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] Example

[0059] likeFigures 1-14 As shown in the figure, an embodiment of the present invention proposes a reconfigurable multimode multiplexing sensing system, comprising: a frequency synthesizer with high-pass signal injection function, used to generate radio frequency signals according to the working mode, which can generate a continuous frequency modulated wave superimposed with a frequency control key shift modulation wave; N transmit channels connected to the frequency synthesizer, used to transmit the radio frequency signals generated by the frequency synthesizer, wherein the transmit channels do not include an up-conversion module; and N receive channels, where N is an integer greater than or equal to 1, used to receive radio frequency signals containing communication signals and / or radar sensing echo signals, and perform one down-conversion processing to output an intermediate frequency signal.

[0060] The transmitting channel does not involve an up-conversion process, thus avoiding the impact of up-conversion on system linearity and noise. The receiving channel uses a single down-conversion to obtain a zero-IF signal or a non-zero-IF signal. Here, the non-zero-IF signal refers to the fact that the center frequency of the radar signal and communication signal obtained by down-conversion is not the DC frequency, but a higher frequency, thus avoiding the DC blocking region and eliminating the need for a second down-conversion operation. In communication systems, the term corresponding to zero-IF generally refers to a superheterodyne signal, which mainly refers to the need for two down-conversions from radio frequency signal to intermediate frequency signal. This is not the non-zero-IF signal mentioned in this invention. To avoid ambiguity and conceptual confusion, this explanation is provided here. Furthermore, the transmitting and receiving radio frequency signal functions under various specific functions can be switched on and off according to different communication or sensing modes, thereby realizing the multi-mode multiplexing function of the transceiver system.

[0061] The intermediate frequency (IF) signal output after down-conversion by the receiving channel is either a zero IF signal or a non-zero IF signal. When the system operates in single-station same-frequency transceiver mode, it is configured as a zero IF signal operating mode; when the system operates in multi-station network mode, it is configured as a non-zero IF signal operating mode, wherein there is a fixed difference between the carrier frequencies of the transmitting and receiving stations, so that the center frequency of the down-converted IF signal is far from the DC region. In the non-zero IF signal operating mode, the system achieves clock and trigger synchronization between multiple RF transceiver systems through communication signals. The IF signal processing module includes an ultra-high-speed analog-to-digital converter (ADC). In the zero IF signal operating mode, the ADC uses noise shaping technology; in the non-zero IF signal operating mode, digital domain bandpass filtering technology is used to process the signal.

[0062] The intermediate frequency (IF) signal processing module includes two IF signal processing paths connected to the receiving channel for processing the IF signal. The IF signal processing module includes independent radar signal processing and communication signal processing paths. The radar signal processing path primarily processes the IF signal corresponding to the target object obtained by mixing the radar reflection signal reflected by the target object through the receiving channel. The communication signal processing path primarily processes the communication IF signal from the outside obtained by mixing the communication signal transmitted by other users through other transceiver systems with the same communication function or another RF transceiver system as described in this embodiment through the receiving channel. The processing includes amplification and demodulation of the required radar or communication signal, as well as filtering, attenuation, and noise reduction of non-target signals, thereby obtaining a radar or communication signal that meets the system's required signal-to-noise ratio. Furthermore, in this embodiment, the two processing paths in the IF signal processing module may share a front-end submodule with the high-speed ADC submodule, but the final terminal still requires two independent radar communication signals or information. Therefore, the two processing paths described in this embodiment still have universality.

[0063] The system can be configured to multiple operating modes, including at least: communication sensing frequency division multiplexing mode, communication sensing time division multiplexing mode, communication operating mode, and sensing operating mode.

[0064] like Figure 2 As shown, the multi-mode multiplexing of the transceiver system can be divided into at least four working modes based on the type of output signal from the transmitting channel: communication-sensing frequency division multiplexing mode, communication-sensing time division multiplexing mode, communication working mode, and sensing (radar) working mode. Among these, the communication-sensing time division multiplexing mode, communication working mode, and sensing working mode have been implemented in previous similar inventions. Therefore, the present invention can switch between these three modes, which can be compatible with such related inventions and has the ability to adapt to more application scenarios. Therefore, the main feature of the present invention in terms of the output working mode of the transmitting channel is that it supports frequency division multiplexing mode, that is, at the same time, only one radio frequency transceiver system can be used to perform efficient simultaneous communication and sensing. Moreover, the non-overlapping nature of the communication signal and the sensing signal (radar signal) sensing different frequency bandwidths ensures the independence of the two signals. In addition, it can also be based on the signal processing method of the receiving channel and the intermediate frequency signal processing module.

[0065] like Figure 3As shown, the operating modes are divided into zero-IF signal mode and non-zero-IF signal mode. Zero-IF signal mode is used when a single transceiver system simultaneously transmits and receives radar signals. In this mode, because the frequency of the signal generated by the frequency synthesizer is the same when it enters the transmit and receive paths, the received communication / sensing signal, after down-conversion, becomes a zero-IF signal with a minimum bandwidth of 0. Non-zero-IF signal mode is used when two or more RF transceiver systems are networked in a multi-site configuration. In this case, it can be used as follows... Figure 3 As shown, transceiver system 1 transmits communication and radar signals, which are then received by transceiver systems 2, 3, ... at the same or other locations. The carrier frequency of transceiver system 1 for transmission has a fixed difference from the carrier frequency of transceiver systems 2, 3, ... for reception. Therefore, after down-conversion in the receiving channel, the resulting intermediate frequency (IF) signal will no longer use the DC frequency as its lowest frequency, thus avoiding the effects of DC blocking. To address the issue of asynchronous radar signal triggering in multi-station transceiver systems, this invention proposes a multi-station radar communication clock synchronization scheme. Since radar and communication signals can be transmitted simultaneously in this system, specific communication signals can be transmitted during multi-station radar sensing. These specific communication signals contain trigger information and other signals, and the hardware layer implements a fast response to these specific trigger signals, thereby achieving trigger signal synchronization. For the integrated design of zero-IF signal processing and non-zero-IF signal processing, this invention employs an ultra-high-speed reconfigurable ADC. When using the zero-IF signal operating mode, due to the extremely high oversampling rate, this invention uses noise shaping. The system employs a shaded ADC to achieve ultra-low noise signal conversion. When using a non-zero intermediate frequency (IF) signal operating mode, a digital domain bandpass filter is used to effectively filter out high-frequency mixing interference and DC blocking, thereby improving sensing accuracy and range. It should be noted that the various modes described above can be switched in real time. Furthermore, it should be pointed out that… Figure 2 and Figure 3 In the schematic diagrams drawn in the diagrams, only the corresponding signal paths and functional modules for starting the operation are marked in different working modes for ease of explanation. This does not mean that the transceiver system only contains these signal paths and functional modules for starting the operation.

[0066] like Figure 4As shown, a frequency synthesizer with high-pass signal injection capability includes: a controlled oscillator (VCO); the VCO is either a voltage-controlled oscillator (VCO) or a digital-controlled oscillator (DCO), and the DAC module can be removed when using a DCO; a phase-locked loop (PLL) connected to the VCO to provide frequency locking; and a frequency modulator configured to generate radar and communication modulation signals. The output of the frequency modulator is connected to the control terminal of the VCO through at least one modulation path, enabling the radar and communication modulation signals to directly modulate the output frequency of the VCO, thus achieving high-pass signal injection. The communication modulation signal is generated using frequency domain on / off keying (F-OOK) technology, which modulates baseband binary data onto a high-frequency carrier, making the spectrum of the communication signal far from the spectrum of the radar signal to ensure signal independence and system stability.

[0067] The radar modulation signal generated by the frequency modulator is used to generate a frequency-modulated continuous wave (FMCW) signal, and the resulting communication modulation signal is used to generate a frequency shift keying (FSK) signal. A dedicated digital-to-analog converter (DAC) for the inductive system is installed on the modulation path. The digital modulation signal output by the frequency modulator is converted into an analog signal by the DAC and then injected into the controlled oscillator. A DAC calibration module is also included for performing nonlinear calibration and / or signal mismatch calibration on the DAC. The calibration method employs a lookup table-based digital predistortion (LUT-DPD) technique. When performing nonlinear calibration of the radar modulation signal, the DAC calibration module is configured to: disconnect the loop of the PLL; scan the DAC control word and use a phase-frequency detector to detect the deviation between the output frequency of the controlled oscillator and the target frequency; iteratively update the weighting matrix according to the deviation until the deviation meets a predetermined norm requirement, and use the final weighting matrix as the calibration lookup table.

[0068] The controlled oscillator has at least two frequency control paths, one of which is connected to the voltage output or digital control word output of the PLL to build a complete PLL loop, thereby realizing the frequency locking function. The other at least one path is connected to the DAC or directly connected to the frequency modulator for high-pass signal injection.

[0069] The frequency modulator described herein has at least two frequency modulation functions: radar and communication. In terms of radar modulation, it can generate a continuous frequency modulated wave (FMCW) modulated signal, and the parameters such as the segmented waveform, slope, duration, and modulation frequency bandwidth of the FMCW modulated signal can be adjusted. In terms of communication modulation, it can at least implement a frequency-shift keying (FSK) modulated wave function, and the FSK rate is variable. Furthermore, the FMCW and FSK functions should be performed without affecting the stability of the PLL. Therefore, this invention introduces a high-pass signal injection technology.

[0070] like Figure 5 As shown, the high-pass signal injection function is characterized by: directly modulating the frequency of the controlled oscillator at the input terminal of the controlled oscillator through a frequency modulator or a frequency modulator via a DAC, and the modulation signal does not affect the stability of the PLL itself, thereby realizing the injection of a higher frequency modulation signal;

[0071] like Figure 5 As shown, the frequency synthesizer in the embodiment can be approximated using the complex frequency domain linear time-invariant system in the figure, where Kvco1 is the frequency conversion rate from PLL to controlled oscillator, Kvco2 is the frequency conversion rate from radar modulation signal output from frequency modulator to controlled oscillator, Kvco3 is the frequency conversion rate from communication modulation signal output from frequency modulator to controlled oscillator, M is the reciprocal of the feedback coefficient of PLL, which is an integer greater than or equal to 1, Kpd is the phase detection gain of PLL, Z(s) is the complex frequency domain transfer function of PLL loop filter, Z2(s) is the complex frequency domain transfer function of filter on radar modulation signal path, Z3(s) is the complex frequency domain transfer function of high-pass, band-pass, or all-pass filter on communication modulation signal path, XO is the external reference source input, and a crystal oscillator circuit is used in this embodiment. Oscillator (XO); Assuming that under a specific condition, the communication frequency modulation signal output by the frequency modulator is Vin_Comm, the input radar frequency modulation signal is Vin_Radar, and the corresponding oscillator frequency is Fvco_out, then the following formula holds:

[0072] Fvco_out=(Z2(s)*Kvco2*Vin_Radar+Z3(s)*Kvco3*Vin_Comm)*(s*M / (s*M-Kpd*Z(s)* Kvco1))+Z2(s)*Kvco2 / s*(s*M*Kpd*Z(s)*Kvco1 / (s*M-Kpd*Z(s)*Kvco1))*Vin_Radar.

[0073] After simplification, we have: Fvco_out = Z2(s)*Kvco2*(1+Kpd*Z(s)*Kvco1 / s)*Hc(s) *Vin_Radar+ Z3(s)*Kvco3*Hc(s)*Vin_Comm.

[0074] Where Hc(s) is the equivalent loop gain:

[0075] Hc(s) = s*M / (s*M-Kpd*Z(s)*Kvco1).

[0076] First, in the model used in this embodiment, the output is frequency, not phase as in a typical phase-locked loop (PLL) model. Therefore, the actual loop equivalent gain differs in form from that of a typical PLL model, but they are equivalent, which is specifically noted here. From the above derivation, it can be seen that the radar modulation signal passes through two signal paths, namely Z2(s)*Kvco2 and Z2(s)*Kvco2 / s*Kpd*Z(s)*Kvco1*Hc(s). Z2(s) can be configured as a low-pass, band-pass, or high-pass filter depending on the application scenario. Therefore, the first signal path can be configured as a high-pass control path, while the second signal path is a low-pass control path used for locking a specific frequency. Similarly, from the above derivation, it can be seen that the communication modulation signal only passes through one high-pass control path, thus the communication modulation signal undergoes high-pass signal injection. In summary, the high-pass signal injection function can directly modulate the oscillator with high-speed, high-bandwidth communication signals or radar signals, thereby generating high-speed, high-bandwidth communication sensing modulation radio frequency signals.

[0077] like Figure 6 As shown, the high-pass signal injection function features include: further including technologies related to ensuring the stability of the phase-locked loop during high-pass signal injection.

[0078] Figure 6 In this context, Φerror represents the phase difference detected by the phase detector. Assuming a specific condition, the communication frequency modulation signal output by the frequency modulator is Vin_Comm, the input radar frequency modulation signal is Vin_Radar, and the corresponding oscillator frequency is Φerror, then the following formula applies:

[0079] Φerror = (Z2(s)*Kvco2 / (s*M)+Ho(s) / s) / (1+Ho(s))*Vin_Radar

[0080] + Z3(s)*Kvco3 / (s*M) / (1+Ho(s))*Vin_Comm + Φoffset.

[0081] Where Ho(s) is the open-loop gain of the phase-locked loop:

[0082] Ho(s) = Kpd*Z(s)*Kvco1 / (s*M).

[0083] Φoffset represents the phase deviation of the system itself.

[0084] Under stable conditions, we need to ensure that the phase difference detected by the phase detector is essentially equal to or equal to 0 over any number of sampling repetition periods. Otherwise, the final PLL frequency output will change due to the phase change, thus causing frequency error. Therefore, we assume that under stable conditions, Φerror(n*T) = Φerror((n+1)*T), where n is any integer and T is the sampling period of the phase detector. To satisfy the stability condition and the independence of radar and communication signals, the radar modulation signal path and the communication modulation signal path are analyzed separately below:

[0085] First, to ensure that radar and communication signals are independent of each other, the following can be achieved:

[0086] Φerror_Radar(n*T) = 0;

[0087] Φerror_Comm(n*T) = 0;

[0088] That is, the phase difference of the system comes only from the phase deviation of the system itself, and the radar and communication modulation signals do not introduce accumulated phase difference in any period;

[0089] Next, analyzing the radar modulation signal separately, the cumulative phase difference within any period is:

[0090] Φerror_Radar(n*T) = IL[(Z2(s)*Kvco2 / (s*M)+Ho(s) / s) / (1+Ho(s))] (Conv)Vin_Radar(nT),

[0091] (s<2*π / T).

[0092] Where IL[*] is the inverse Laplace transform, and (Conv) is the convolution operation between the preceding and following terms. Analyzing the above formula, we can see that if the transfer function term IL[(Z2(s)*Kvco2 / (s*M)+Ho(s) / s) / (1+Ho(s))] is not 0, since the system has a pole at s=0, the phase difference will be infinite when s approaches 0, i.e., when the input signal is a DC signal. When s starts to approach infinity from 0, i.e., when the input signal frequency gradually increases, the phase difference will gradually decrease, and it will be inversely proportional to the frequency to a certain power. Furthermore, since the input of the radar modulation signal is generally a periodic pulse signal, triangular wave signal, or sawtooth wave signal with a period in the range of microseconds to milliseconds, corresponding to a bandwidth below 1MHz, if the transfer function term is not 0 within the radar modulation signal bandwidth, it will inevitably cause a large phase difference, leading to system instability. Therefore, under this condition, the condition for system stability is that the transfer function term should approach 0 within the radar modulation signal bandwidth, i.e.:

[0093] (Z2(s)*Kvco2 / (s*M)+Ho(s) / s) / (1+Ho(s)) -> 0,s ->0.

[0094] like Figure 7 As shown, a feasible approach is to make Z2(s)*Kvco2 / M = - Ho(s) = Kpd*Z(s)*Kvco1 / (s*M), meaning the gains of the two paths of the radar modulation signal input are exactly equal and opposite, thereby suppressing the phase difference caused by the radar modulation signal at low frequencies. Figure 7 The Bode plot of the transfer function from Vin_Radar to error_Radar in this embodiment is given under a certain parameter, and the in-band phase error is small.

[0095] Finally, the communication signal is analyzed separately. Similarly, the cumulative phase difference of the communication signal within one cycle is:

[0096] Φerror_Comm(n*T) = IL[(Z3(s)*Kvco3 / (s*M)* / (1+Ho(s))] (Conv) Vin_Comm(nT),

[0097] (s<2*π / T).

[0098] like Figure 8As shown, firstly, the transfer function term (Z3(s)*Kvco3 / (s*M) / (1+Ho(s)) is analyzed. When s approaches 0, there exists both an infinitely large quantity 1 / (s*M) and an infinitesimal quantity 1 / (1+Ho(s)). Therefore, the zero-pole characteristic of the transfer function depends on the order of the infinitely large and infinitesimal quantities. The infinitely large quantity 1 / (s*M) is a first-order pole, and 1 / (1+Ho(s)) is generally a zero of order 2 or higher, which depends on the order of the phase-locked loop. Therefore, it ultimately exhibits zero-point characteristics when s approaches 0, that is, the transfer function approaches 0. When s approaches infinity, 1 / (s*M) approaches 0, and 1 / (1+Ho(s)) approaches 1. The Z3(s)*Kvco3 term depends on the zero of the filter Z3(s). Regarding pole characteristics, in order to ensure wide bandwidth communication, a high-pass signal injection technique was introduced earlier. Therefore, high-pass, band-pass, or all-pass filters are required. This means that within the available communication bandwidth, Z3(s) does not contribute poles and can therefore be considered a constant term. When s approaches infinity, the transfer function of the communication modulation signal exhibits a low-order low-pass characteristic. In summary, the overall phase difference transfer function exhibits band-pass characteristics. This means that to ensure system stability, the bandwidth of the communication modulation signal should be selected in the low-frequency or high-frequency region to avoid the band-pass characteristic of the phase difference transfer function. Since the radar modulation signal in the previous example already used the low-frequency region, to ensure the independence of the two modulation signals and the wide bandwidth of the communication modulation signal, a higher frequency is selected as the bandwidth for the communication modulation signal in this embodiment. Figure 8 The Bode plot of the transfer function from Vin_Comm to error_Comm in this embodiment is given under a certain parameter, and the in-band phase error is small.

[0099] like Figure 9 As shown, the FSK modulation function is characterized by further including Frequency-domain On-off Keying (F-OOK) technology. Its function is to generate a corresponding modulation signal waveform based on the binary data provided by the communication baseband system. According to the above stability analysis, it is necessary to shift the binary data with a starting frequency of 0 provided by the baseband system to a higher frequency bandwidth. This embodiment employs... Figure 9Modulation is performed as shown. First, a fixed-frequency modulation clock provided by the system serves as the carrier wave. Its time-domain signal is a square wave signal with a period of Tm, and the maximum and minimum values ​​are opposite in direction (for simplicity, only one side of the bilateral spectrum is shown, and will not be elaborated further below). Its spectrum is the Dirac function at odd harmonic frequencies. The input signal is a random binary signal with a variation period of Tm, so its spectrum is a rectangular spectrum symmetrical about the 0 frequency with a single-sided spectral bandwidth of 1 / 2Tm. Next, the time-domain signal is multiplied, and the frequency-domain signal is convolved to obtain the communication modulation signal in both the time and frequency domains. The result in the time domain is that when the input signal is 0, the output modulation signal is 0, and when the input signal is 1, the output signal is the carrier waveform. In the frequency domain, it is an up-conversion shift of the signal rectangular spectrum, so that the low-frequency radar bandwidth does not contain the communication modulation signal, thus ensuring the independence between the communication signal and the radar signal and the stability of the PLL.

[0100] like Figure 10 As shown, the DAC includes a radar path and a communication path, as well as its calibration algorithm and calibration circuit. In the actual circuit, coefficients such as Kvco2 and Kvco3 change with the DAC's voltage output, which leads to nonlinearity in the actual radar modulation signal and mismatch in the communication modulation signal. For the radar modulation signal, Figure 10 As shown, due to the existence of a low-pass modulation path, when a phase difference is caused by nonlinearity, the phase of the PLL can be compensated by loop filtering. However, the output range of the loop filter is limited, so calibration methods are needed to limit the nonlinearity of the DAC to a certain range.

[0101] like Figure 11 As shown, for communication modulation signals, if the DAC has signal mismatch, that is, the maximum and minimum values ​​of the output modulation signal are not completely opposite and equal, or the duty cycle of the modulation carrier is not 50%, it can be equivalent to the amplitude and duty cycle mismatch of the modulation carrier. This will cause the frequency domain signal to have a DC component, which will cause the spectrum of the final convolutional communication modulation signal to have a component that falls within the radar bandwidth, resulting in signal aliasing and PLL instability. Therefore, the communication modulation signal also needs to be compensated by calibration algorithms and circuits.

[0102] like Figure 12As shown, the calibration algorithm and circuit of the DAC are characterized by the following: for radar modulation signals, the nonlinearity mainly originates from the nonlinearity of the DAC circuit itself and the nonlinearity of the DAC-to-VCO conversion rate Kvco2. Therefore, it is mainly addressed through a lookup table (LUT) – digital predistortion technology. The calibration of the DAC (Digital Frequency Divider) is performed as follows: First, the PLL loop is disconnected. Then, the DAC scans its control word and multiplies it by the initial weighting matrix, which is an identity matrix with only diagonal elements equal to 1. All voltage signals and their corresponding frequency modulation frequencies are output. During the scan, the phase frequency detector detects the relationship between the current output frequency divided by the target frequency division ratio and the reference frequency, thereby determining the relationship between the output frequency and the target frequency. After one scan, all control words and their corresponding discrimination vectors for the relationship between the output frequency and the target frequency are determined. The discrimination vectors are then used to modify the values ​​of the diagonal elements in the weighting matrix, and the DAC output is scanned again to obtain new discrimination vectors. This process is repeated until the discrimination vectors meet specific norm requirements, at which point the calibration can be stopped, thus obtaining the output frequency of the DAC with better linearity. The weighting matrix B is the corresponding lookup table.

[0103] like Figure 13 As shown, for communication modulation signals, the mismatch mainly comes from the mismatch between the maximum and minimum values, as well as the duty cycle mismatch. The method also uses the LUT-DPD method. In radar modulation signal calibration, we have obtained a relatively linear lookup table after calibration, that is, we have obtained the linear relationship between the control word and the output frequency. Therefore, we disconnect the PLL loop and initialize the required maximum value Amax, minimum value Amin, and intermediate value A0 when FSK is 0. At the same time, we also know that the frequency relationship corresponding to A0 is Fref*M. Then, we make all FSK input signals 1, thereby generating a modulation frequency of several cycles. Then, we detect the relationship between the output frequency divided by M and the reference frequency through the phase frequency detector, so that we can know the mismatch between Amax and Amin. The discrimination vector P composed of the discrimination elements of each discrimination is quantized. Then we determine whether the discrimination vector meets the specific norm requirement. If it does not meet the requirement, we update the values ​​of Amax and Amin through the discrimination vector and perform discrimination again until the discrimination requirement is met, then the calibration ends. Thus, we obtain the Amax and Amin values ​​corresponding to the specific control word A0.

[0104] like Figure 14 As shown, a reconfigurable multimodal multiplexing synesthesia method includes the following steps:

[0105] Mode configuration steps: Based on the application scenario, configure the system to any one of the following: communication sensing frequency division multiplexing, communication sensing time division multiplexing, communication working mode, or sensing working mode;

[0106] Signal generation steps: The required radar RF signal and / or communication RF signal are directly generated using a single-frequency synthesizer and high-pass signal injection technology.

[0107] Signal transmission steps: The radio frequency signal is transmitted through the transmission channel, which does not involve an up-conversion process;

[0108] Signal reception and down-conversion steps: Receive the signal through the receiving channel and perform a down-conversion to obtain the intermediate frequency signal;

[0109] Signal processing steps: The intermediate frequency signal is separated and processed by the intermediate frequency signal processing module to obtain the sensing target information and communication data respectively.

[0110] Specifically, it also includes: achieving synchronization between the transmitting station and at least one receiving station through trigger information carried by the communication signal; and maintaining a fixed deviation between the carrier frequencies of the transmitting station and the receiving station to ensure that a non-zero intermediate frequency signal is obtained after downconversion at the receiving end.

[0111] Specifically, in this embodiment, the controlled oscillator is a voltage-controlled oscillator, but in some embodiments, a digitally controlled oscillator can be used, and the DAC module can also be removed when using a DCO.

[0112] Specifically, the two processing paths described in the intermediate frequency signal processing module may share a previous sub-module before a certain sub-module, and may even share it at the output end for further processing at the back end.

[0113] Specifically, the DAC calibration method can be replaced, such as using a real-time calibration scheme instead of the LUT-DPD scheme, which can still achieve the calibration function.

[0114] Specifically, the control circuitry for the multiple transmit / receive antenna array may be implemented off-chip in alternative embodiments.

[0115] Specifically, in alternative embodiments, the on-chip crystal oscillator circuit may use the following approach: an off-chip active crystal oscillator chip is used, and the on-chip start-up circuit is no longer designed; only the drive circuit is used.

[0116] Specifically, the downconversion operation of the receiving path may be directly replaced by an ultra-high-speed ADC, at which point the receiving path will become a complete amplification path.

[0117] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A reconfigurable multimode multiplexing sensing system, characterized in that, include: A frequency synthesizer with high-pass signal injection function is used to generate radio frequency signals according to the working mode, and generate a continuous frequency modulated wave superimposed with a frequency control keyshift modulation wave. N transmission channels, where N≥1, are connected to the frequency synthesizer and are used to transmit the radio frequency signals generated by the frequency synthesizer. The transmission channels do not include the upconversion module. N receiving channels, where N≥1, are used to receive radio frequency signals containing communication signals and / or radar sensing echo signals, and perform one down-conversion process to output intermediate frequency signals; An intermediate frequency signal processing module, connected to the receiving channel, is used to process the intermediate frequency signal. The intermediate frequency signal processing module includes independent radar signal processing paths and communication signal processing paths. The system can be configured to multiple operating modes, including at least: communication sensing frequency division multiplexing mode, communication sensing time division multiplexing mode, communication operating mode, and sensing operating mode.

2. The reconfigurable multimode multiplexing sensing system according to claim 1, characterized in that: The frequency synthesizer includes: Controlled oscillator; A phase-locked loop (PLL) is connected to the controlled oscillator to provide frequency locking functionality; A frequency modulator configured to generate radar modulated signals and communication modulated signals; The output of the frequency modulator is connected to the control terminal of the controlled oscillator through at least one modulation path, so that the radar modulation signal and the communication modulation signal can directly modulate the output frequency of the controlled oscillator to achieve high-pass signal injection.

3. The reconfigurable multimode multiplexing sensing system according to claim 2, characterized in that: The radar modulation signal generated by the frequency modulator is used to generate a frequency modulated continuous wave (FMCW) signal, and the communication modulation signal generated by it is used to generate a frequency shift keying (FSK) signal. The modulation path is equipped with a dedicated DAC for the induction system. The digital modulation signal output by the frequency modulator is converted into an analog signal by the DAC and then injected into the controlled oscillator.

4. A reconfigurable multimode multiplexing sensing system according to claim 3, characterized in that: It also includes a DAC calibration module for performing nonlinear calibration and / or signal mismatch calibration on the DAC, wherein the calibration method employs lookup table-based digital predistortion (LUT-DPD) technology. When the DAC calibration module performs nonlinear calibration of the radar modulation signal, it is configured to disconnect the loop of the PLL. Scan the DAC control word and use a phase frequency detector to detect the deviation between the output frequency of the controlled oscillator and the target frequency; The weighted matrix is ​​iteratively updated based on the deviation until the deviation meets the predetermined norm requirement, and the final weighted matrix is ​​used as the calibration lookup table.

5. A reconfigurable multimode multiplexing sensing system according to claim 2, characterized in that: The communication modulation signal is generated using frequency domain on / off keying (F-OOK) technology, which modulates baseband binary data onto a high-frequency carrier, making the spectrum of the communication signal far away from the spectrum of the radar signal.

6. A reconfigurable multimode multiplexing sensing system according to claim 1, characterized in that: The intermediate frequency signal output after downconversion by the receiving channel is either a zero intermediate frequency signal or a non-zero intermediate frequency signal. When the system is operating in single-station same-frequency transceiver mode, it is configured to operate in zero intermediate frequency signal mode; When the system operates in multi-station networking mode, it is configured to operate in non-zero intermediate frequency signal mode, where there is a fixed difference between the carrier frequencies of the transmitting station and the receiving station, so that the center frequency of the intermediate frequency signal after down-conversion is far away from the DC region.

7. A reconfigurable multimode multiplexing sensing system according to claim 6, characterized in that: In the non-zero intermediate frequency signal operating mode, the system achieves clock and trigger synchronization between multiple radio frequency transceiver systems through communication signals.

8. A reconfigurable multimode multiplexing sensing system according to claim 1, characterized in that: The intermediate frequency signal processing module includes an ultra-high-speed analog-to-digital converter (ADC). In zero-IF signal operating mode, the ADC employs noise shaping technology; In the non-zero intermediate frequency signal operating mode, digital domain bandpass filtering technology is used to process the signal.

9. A reconfigurable multimode multiplexing sensing method, the method being used based on a reconfigurable multimode multiplexing sensing system according to any one of claims 1-8, characterized in that: Includes the following steps: Mode configuration steps: Based on the application scenario, configure the system to any one of the following: communication sensing frequency division multiplexing, communication sensing time division multiplexing, communication working mode, or sensing working mode; Signal generation steps: The required radar RF signal and / or communication RF signal are directly generated using a single-frequency synthesizer and high-pass signal injection technology. Signal transmission steps: The radio frequency signal is transmitted through the transmission channel, which does not involve an up-conversion process; Signal reception and down-conversion steps: Receive the signal through the receiving channel and perform a down-conversion to obtain the intermediate frequency signal; Signal processing steps: The intermediate frequency signal is separated and processed by the intermediate frequency signal processing module to obtain the sensing target information and communication data respectively.

10. The reconfigurable multimode multiplexing synesthesia method according to claim 1, characterized in that: Also includes: Synchronization between the transmitting station and at least one receiving station is achieved by using trigger information carried by communication signals; To ensure that the carrier frequencies of the transmitting and receiving stations are kept at a fixed deviation, a non-zero intermediate frequency signal is obtained after downconversion at the receiving end.

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