A method and system for generating a communication and perception integrated signal based on DPIM for a laser radar

Abstract

The application discloses a kind of laser radar communication sensing integration signal generation method and system based on DPIM, and it relates to optical communication and laser radar technical field.The method comprises the following steps: obtaining the channel state level of space sector;According to the channel state level of space sector, the corresponding DPIM parameter is determined;According to the modulation order, the bit grouping rule of communication bit stream is determined, and the grouped communication bit stream is mapped in combination with the basic time slot width, to obtain the initial pulse sequence composed of pulse and space time slot alternately arranged;Each pulse in the initial pulse sequence is converted into a sweep pulse with wideband frequency variation characteristics, to generate a communication sensing integrated signal.The application fully considers the influence of complex environment on signal transmission, and by combining channel state to adaptively adjust DPIM parameter, the signal generation can dynamically fit the current channel condition, thereby improving the communication reliability of integrated system.

Description

Technical Field

[0001] This invention relates to the field of optical communication and lidar technology, specifically to a lidar communication and sensing integrated signal generation method and system based on DPIM. Background Technology

[0002] With the rapid development of autonomous driving and intelligent transportation systems, integrated LiDAR communication and sensing technology has become an important means of environmental perception and data transmission. The demands of various application scenarios are constantly expanding, and the system can simultaneously achieve high-precision ranging and high-speed data communication through integrated signals. As a crucial tool for reducing system hardware complexity and power consumption, the rational design and efficient generation of integrated communication and sensing signals have a significant impact on the overall system performance.

[0003] Currently, the generation method for integrated communication and sensing signals in lidar mainly relies on globally unified fixed DPIM (Digital Pulse Interval Modulation) parameters. By using fixed-parameter DPIM technology to encode communication data, a generation strategy for the integrated signal is determined to meet the basic requirements of target detection and data broadcasting.

[0004] However, relying solely on globally unified fixed DPIM parameters makes it difficult to accurately adapt to the drastic changes in channel states in different spatial directions in complex atmospheric environments. This results in the determination of signal generation strategies being unable to resist channel interference in harsh environments or to make full use of high-quality channels, thereby reducing the communication reliability of the integrated system. Summary of the Invention

[0005] To address the aforementioned shortcomings, a method and system for generating integrated LiDAR communication and sensing signals based on DPIM is provided.

[0006] In a first aspect, the present invention provides a method for generating integrated LiDAR communication and sensing signals based on DPIM, the method comprising: Acquire optical echo signals at different spatial pointing angles generated by lidar scanning and detecting the target space, and extract the channel fading characteristic parameters of the optical echo signals; The atmospheric turbulence intensity index is calculated based on the channel fading characteristic parameters at the corresponding spatial pointing angle, and the target space is divided into multiple spatial sectors with different channel state levels according to the atmospheric turbulence intensity index. When performing a communication task for the currently pointed spatial sector, the communication bit stream to be sent is obtained, and the corresponding DPIM parameters are determined according to the channel state level of the currently pointed spatial sector. The DPIM parameters include the modulation order and the basic time slot width. The bit grouping rule of the communication bit stream to be transmitted is determined according to the modulation order of the corresponding DPIM parameter. The communication bit stream to be transmitted is grouped and mapped according to the basic time slot width of the corresponding DPIM parameter to obtain an initial pulse sequence composed of alternating pulses and empty time slots. Each pulse in the initial pulse sequence is converted into a swept frequency pulse with wideband frequency variation characteristics to generate a communication sensing integrated signal corresponding to the communication bit stream to be transmitted.

[0007] By employing the above technical solution, optical echo signals generated by lidar scanning and detecting the target space at different spatial pointing angles are acquired, and channel fading characteristic parameters are extracted. This allows for the direct quantification of atmospheric turbulence intensity indicators at the corresponding spatial pointing angle using real echo data. Furthermore, based on these atmospheric turbulence intensity indicators, the target space is divided into multiple spatial sectors with different channel state levels, enabling the system to accurately grasp the actual channel conditions at each spatial orientation. When performing communication tasks for the currently pointing spatial sector, the corresponding DPIM parameters are determined according to the channel state level of the spatial sector, ensuring that the modulation order and basic time slot width match the channel conditions of the current sector, avoiding increased bit errors or bandwidth waste caused by a single fixed parameter. The bit grouping rules of the communication bit stream are determined based on the modulation order and mapped using the basic time slot width. The generated initial pulse sequence, composed of alternating pulses and empty time slots, can directly adapt to the transmission environment of the current spatial sector. Each pulse in the initial pulse sequence is converted into a swept-frequency pulse with broadband frequency variation characteristics to generate an integrated communication and sensing signal. The broadband frequency variation characteristics are used to increase the signal bandwidth, enabling the signal to effectively resist channel fading and interference in complex atmospheric environments, ensuring the synchronous and stable transmission of communication data and sensing detection, thereby improving the communication reliability of the integrated system.

[0008] Secondly, this invention provides a DPIM-based integrated signal generation system for lidar communication and sensing, the system comprising: The signal acquisition and feature extraction module is used to acquire optical echo signals at different spatial pointing angles generated by the lidar scanning and detecting the target space, and to extract the channel fading characteristic parameters of the optical echo signals. The sector partitioning module is used to calculate the atmospheric turbulence intensity index under the corresponding spatial pointing angle based on the channel fading characteristic parameters, and to divide the target space into multiple spatial sectors with different channel state levels according to the atmospheric turbulence intensity index. The parameter determination module is used to obtain the communication bit stream to be sent when performing a communication task for the currently pointed spatial sector, and determine the corresponding DPIM parameters according to the channel state level of the currently pointed spatial sector. The DPIM parameters include the modulation order and the basic time slot width. The sequence mapping module is used to determine the bit grouping rules of the communication bit stream to be transmitted according to the modulation order of the corresponding DPIM parameter, group the communication bit stream to be transmitted, and map the grouped communication bit stream in combination with the basic time slot width of the corresponding DPIM parameter to obtain an initial pulse sequence composed of alternating pulses and empty time slots. The signal generation module is used to convert each pulse in the initial pulse sequence into a swept frequency pulse with wideband frequency variation characteristics, thereby generating a communication sensing integrated signal corresponding to the communication bit stream to be transmitted. Attached Figure Description

[0009] Figure 1 A flowchart illustrating a DPIM-based integrated signal generation method for lidar communication and sensing provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a DPIM signal mapping process for a communication bit stream provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a communication-sensing integrated signal timing structure provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the architecture of a DPIM-based integrated signal generation system for lidar communication and sensing, provided as an embodiment of the present invention. Detailed Implementation

[0010] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0011] Example 1 like Figure 1 As shown, a method for generating integrated communication and sensing signals for lidar based on DPIM is presented. The method includes: Acquire optical echo signals at different spatial pointing angles generated by lidar scanning and detecting the target space, and extract the channel fading characteristic parameters of the optical echo signals; The atmospheric turbulence intensity index is calculated based on the channel fading characteristic parameters at the corresponding spatial pointing angle, and the target space is divided into multiple spatial sectors with different channel state levels according to the atmospheric turbulence intensity index. When performing a communication task for the currently pointed spatial sector, the communication bit stream to be sent is obtained, and the corresponding DPIM parameters are determined according to the channel state level of the currently pointed spatial sector. The DPIM parameters include the modulation order and the basic time slot width. The bit grouping rule of the communication bit stream to be transmitted is determined according to the modulation order of the corresponding DPIM parameter. The communication bit stream to be transmitted is grouped and mapped according to the basic time slot width of the corresponding DPIM parameter to obtain an initial pulse sequence composed of alternating pulses and empty time slots. Each pulse in the initial pulse sequence is converted into a swept frequency pulse with wideband frequency variation characteristics to generate a communication sensing integrated signal corresponding to the communication bit stream to be transmitted.

[0012] Specifically, this embodiment is applied to a vehicle-mounted 1550nm band fiber optic lidar communication and sensing integrated system. The lidar has a horizontal scanning range of 0°~360°, an angular resolution of 0.1°, a maximum detection distance of 200m, and a system sampling rate of 1GSa / s. During operation, the lidar first performs an all-around scan of the target space, with a scan cycle of 100ms. After each full-space scan, the channel status level of the spatial sector is updated synchronously to ensure that the sector division matches the real-time atmospheric turbulence state. During the scanning process, the system receives optical echo signals at different spatial pointing angles through a photodetector with a response bandwidth of no less than 1GHz. By analyzing the amplitude fluctuations and phase distortion of the optical echo signals, channel fading characteristic parameters reflecting channel quality are extracted. Subsequently, using the extracted channel fading characteristic parameters, the atmospheric turbulence intensity index at each spatial pointing angle is calculated. The atmospheric turbulence intensity index directly reflects the degree of atmospheric disturbance affecting optical signal transmission in that direction; the larger the index value, the more severe the channel fading. Based on the calculated atmospheric turbulence intensity index, the system divides the entire target space into multiple spatial sectors and assigns different channel state levels to each sector. For example, areas with high turbulence intensity are classified as low channel state level sectors, while areas with low turbulence intensity are classified as high channel state level sectors. In this embodiment, the channel state levels are divided into three levels from best to worst: Level 1, Level 2, and Level 3.

[0013] When the lidar system prepares to perform a communication task in the currently pointed spatial sector, it first acquires the communication bit stream to be transmitted via the vehicle-mounted Ethernet. The communication bit stream is binary data encoded with CRC checksum. Next, the system reads the channel state level corresponding to the currently pointed spatial sector and adaptively determines the DPIM parameters accordingly. The DPIM parameters mainly include the modulation order and the basic time slot width. In sectors with lower channel state levels, the system selects a lower modulation order and a wider basic time slot width to reduce the bit error rate; while in sectors with higher channel state levels, the system selects a higher modulation order and a narrower basic time slot width to improve the communication rate. After determining the modulation order, the system determines the bit grouping rules of the communication bit stream based on the modulation order, dividing the continuous communication bit stream into multiple fixed-length bit groups. Then, combined with the determined basic time slot width, the grouped communication bit stream is mapped, mapping each bit group to a pulse at a specific position and several empty time slots, thus obtaining an initial pulse sequence composed of alternating pulses and empty time slots.

[0014] To achieve integrated communication and sensing and further enhance the signal's anti-interference capability, the system performs waveform conversion on the generated initial pulse sequence. Specifically, each regular pulse in the initial pulse sequence is converted into a swept-frequency pulse with wideband frequency variation characteristics, including linear frequency-modulated (LFM) pulses and nonlinear frequency-modulated (NFM) pulses. This swept-frequency pulse modulates only the frequency of the laser carrier, completely preserving the original pulse's time-domain rising edge, falling edge, and time width, without changing the pulse's time position in the DPIM symbol. Therefore, it does not affect the receiver's detection of pulse intervals or demodulation of communication information. Simultaneously, the swept-frequency pulse possesses a large bandwidth, providing high-resolution distance and velocity sensing capabilities. The distance resolution is determined by the swept-frequency bandwidth, and the velocity measurement accuracy is determined by the swept-frequency time. After the above conversion, the system finally generates the integrated communication and sensing signal corresponding to the communication bit stream to be transmitted. This signal is amplified by the fiber optic amplifier at the laser transmitter and transmitted to the target space via a scanning galvanometer. This enables reliable data communication in complex atmospheric channels and allows for high-precision target detection and sensing through pulse compression processing of the received echo.

[0015] Example 2 As a preferred embodiment of the present invention, based on Example 1, the channel fading characteristic parameters of the optical echo signal are extracted, including: Envelope detection and low-pass filtering are performed on the optical echo signal to obtain the slowly varying envelope signal of the optical intensity; Calculate the light intensity variance and light intensity mean of the slowly varying envelope signal within a preset time window, and use the ratio of the light intensity variance to the square of the light intensity mean as the light intensity scintillation index. Autocorrelation analysis is performed on the slowly varying envelope signal to obtain the time delay corresponding to the decrease of the autocorrelation function to a preset percentage of the peak value, which is used as the channel coherence time. By combining the light intensity scintillation index and the channel coherence time, channel fading characteristic parameters are constructed.

[0016] Specifically, after receiving the optical echo signal, the system first performs signal preprocessing to extract intensity variation information. The system processes the high-frequency optical echo signal using Hilbert transform envelope detection technology to extract the signal amplitude profile. The sampling rate of the envelope detection is consistent with the system sampling rate, at 1 GSa / s. Subsequently, an 8th-order Butterworth low-pass filter with a cutoff frequency of 1 kHz is used to filter out high-frequency noise and carrier remnants in the detected signal, thereby obtaining a slowly varying envelope signal that reflects the intensity fluctuations caused by atmospheric turbulence. The intensity fluctuation frequency caused by atmospheric turbulence is typically within 1 kHz, and this filtering parameter can completely preserve the turbulence characteristics while filtering out irrelevant interference. This processing removes irrelevant high-frequency interference and retains the low-frequency envelope variations affected by the channel environment. After acquiring the slowly varying envelope signal, the system sets a fixed preset time window of 100 ms, consistent with the full-space scanning period of the lidar, and performs statistical analysis on the slowly varying envelope signal within this window. The system calculates the intensity variance and mean intensity of the slowly varying envelope signal within this preset time window. The intensity variance reflects the fluctuation range of the optical signal intensity, while the intensity mean represents the average received optical power. Next, the system divides the calculated intensity variance by the square of the intensity mean to obtain the intensity scintillation index. Specifically, let the instantaneous intensity of the slowly varying envelope signal be... The average light intensity within the preset time window is denoted as The variance of light intensity is denoted as Then the light intensity flicker index The calculation formula is: Formula (1): This embodiment provides a specific calculation example: the average intensity of the slowly varying envelope signal light collected within a 100ms time window of a certain spatial pointing angle. Light intensity variance Substituting into formula (1), the light intensity scintillation index is calculated. This value is consistent with the characteristics of a weakly turbulent channel. If the light intensity variance increases to 0.256V², while the light intensity mean remains unchanged, the light intensity scintillation index is 0.4, which is consistent with the characteristics of a strongly turbulent channel. This index can accurately quantify the scintillation effect of atmospheric turbulence on the light signal intensity. The larger the value, the more severe the light intensity scintillation and the more severe the channel fading.

[0017] At the same time, the system also needs to evaluate the rate at which the channel state changes over time. The system performs autocorrelation analysis on the slowly varying envelope signal and calculates the corresponding autocorrelation function. The formula for calculating the autocorrelation function R(τ) is: Formula (2): in, For time delay, This is a mathematical expectation operation.

[0018] Subsequently, the system searches the autocorrelation function curve for the time delay corresponding to the decrease in its value from the maximum peak to 36.8% of the peak (i.e., 1 / e, where e is the natural constant). This preset ratio is a common standard in optical communication for characterizing channel coherence time. This specific time delay is extracted as the channel coherence time, which intuitively represents the length of time the channel maintains a stable state. The longer the coherence time, the more stable the channel state; the shorter the coherence time, the stronger the time-varying characteristics of the channel. In this embodiment, if the time delay corresponding to the autocorrelation function decreasing from the peak to 36.8% is 5ms, then the channel coherence time for this spatial pointing angle is 5ms.

[0019] Finally, the system combines the light intensity scintillation index, which reflects the amplitude fluctuation, with the channel coherence time, which reflects the time-varying characteristics, to construct a complete channel fading feature parameter in the form of a two-dimensional vector. Through the above process, the system can comprehensively characterize the atmospheric channel fading characteristics under the current spatial pointing angle from both amplitude and time dimensions, providing reliable data support for subsequent accurate assessment of atmospheric turbulence intensity indicators.

[0020] Example 3 As a preferred embodiment of the present invention, based on Example 2, the atmospheric turbulence intensity index at the corresponding spatial pointing angle is calculated based on the channel fading characteristic parameters, and the target space is divided into multiple spatial sectors with different channel state levels according to the atmospheric turbulence intensity index, including: The weighting coefficients corresponding to different channel fading characteristic parameters are obtained, and the light intensity scintillation index and channel coherence time are weighted and fused to obtain the atmospheric turbulence intensity index under the corresponding spatial pointing angle. The atmospheric turbulence intensity indices under all spatial pointing angles in the target space are constructed into a one-dimensional dataset, and the K-means clustering algorithm is used to perform cluster analysis on the one-dimensional dataset to obtain multiple cluster centers; Based on the size relationship of each cluster center, a corresponding channel state level is assigned to each cluster. Scanning regions belonging to the same cluster and with adjacent spatial pointing angles are merged to generate multiple spatial sectors with different channel state levels.

[0021] Specifically, after obtaining the light intensity scintillation index and channel coherence time, the system needs to comprehensively evaluate the overall turbulence situation by combining these two parameters. The system first obtains the weighting coefficients corresponding to different pre-set channel fading characteristic parameters. In this embodiment, through offline simulation optimization of the vehicle-mounted LiDAR communication scenario, the weighting coefficient corresponding to the light intensity scintillation index is determined to be 0.7, and the weighting coefficient corresponding to the channel coherence time is 0.3. This weighting allocation adapts to the dominant influence of light intensity scintillation on the bit error rate in the vehicle-mounted scenario. Since the light intensity scintillation index and channel coherence time have different degrees of influence on communication quality, the system uses these weighting coefficients to perform a weighted fusion calculation of the light intensity scintillation index and channel coherence time.

[0022] Specifically, the formula for calculating the atmospheric turbulence intensity index C is: Formula (3): in, This is the weighting coefficient for the light intensity scintillation index. The weighting coefficients for the channel coherence time. The light intensity flicker index, Channel coherence time (in milliseconds). Using... The reason is that the shorter the coherence time, the stronger the channel time variation, the more severe the turbulence, and the larger the corresponding index value, which is consistent with the trend of the light intensity scintillation index.

[0023] This embodiment provides a specific calculation example: the scintillation index of a certain spatial pointing angle. Channel coherence time Substituting into formula (3), the atmospheric turbulence intensity index C is calculated as C = 0.7 × 0.08 + 0.3 × (1 / 5) = 0.056 + 0.06 = 0.116; if the light intensity scintillation index of another spatial pointing angle... Channel coherence time Therefore, the atmospheric turbulence intensity index C = 0.7 × 0.4 + 0.3 × (1 / 1) = 0.28 + 0.3 = 0.58. Through this weighted fusion method, the system can accurately calculate the atmospheric turbulence intensity index at the corresponding spatial pointing angle. This index comprehensively reflects the channel severity in that direction; the larger the value, the worse the channel quality.

[0024] After the lidar completes scanning of the entire target space, the system collects the atmospheric turbulence intensity indices calculated at all spatial pointing angles within the target space, constructing a one-dimensional dataset. In this embodiment, the lidar scans horizontally from 0° to 360° with an angular resolution of 0.1°, therefore the one-dimensional dataset contains 3600 data points. To effectively classify the complex channel environment, the system employs the K-means clustering algorithm to perform cluster analysis on this one-dimensional dataset. The number of clusters is pre-set to 3, consistent with the number of channel state levels. The initial cluster centers are set to equal intervals of 0.1, 0.3, and 0.5, the maximum number of iterations is set to 100, and the convergence threshold is set to 1e-5. Through iterative calculation, the K-means clustering algorithm groups data points with similar atmospheric turbulence intensity indices into the same cluster, ultimately obtaining three stable cluster centers.

[0025] Subsequently, the system assigns a corresponding channel status level to each cluster based on the size relationship of the cluster centers: the cluster with the smallest cluster center value is assigned a level 1 channel status level (excellent channel); the cluster with the middle cluster center value is assigned a level 2 channel status level (medium channel); and the cluster with the largest cluster center value is assigned a level 3 channel status level (poor channel). For example, if the three cluster centers obtained after iteration are 0.12, 0.35, and 0.6, then they are assigned level 1, level 2, and level 3 channel status levels respectively.

[0026] After completing the level allocation, the system needs to transform the discrete angle data into continuous spatial physical regions. The system traverses the spatial angle domain from 0° to 360°, merging scan areas belonging to the same cluster and with adjacent spatial pointing angles. The adjacency determination rule is: two scan points with an angle difference ≤ 0.5° and belonging to the same cluster are considered adjacent regions. For example, if continuous pointing angles from 30° to 45° all belong to the same Level 1 channel state cluster, the system will merge these adjacent angle regions into a complete spatial sector with an angle range of 30°~45° and a channel state level of 1. Through this merging operation, the system ultimately generates multiple continuous spatial sectors with different channel state levels. This not only simplifies the spatial scheduling complexity of subsequent communication tasks but also ensures that the lidar can use unified and optimally matched communication parameters when performing tasks within a specific sector.

[0027] Example 4 As a preferred embodiment of the present invention, based on Embodiment 1, the corresponding DPIM parameters are determined according to the channel state level of the currently pointed spatial sector, including: A mapping table between channel state levels and target bit error rates is pre-constructed, and the corresponding target bit error rate is obtained by querying the channel state level of the currently pointed spatial sector. Based on the target bit error rate and the system signal-to-noise ratio of the lidar, calculate the maximum usable modulation order that meets the communication reliability requirements; Based on the sensing distance resolution requirements of the lidar, the upper limit of the pulse width is determined, and the corresponding basic time slot width is calculated in combination with the maximum available modulation order; The maximum available modulation order and the corresponding basic time slot width are used as the DPIM parameters for the current spatial sector.

[0028] Specifically, when determining DPIM parameters, the system first needs to clarify the performance requirements under the current channel environment. The system pre-constructs a mapping table between channel state levels and target bit error rates. This table records in detail the bit error rate thresholds that the system can tolerate under different channel severity levels. The mapping table is shown below: When the lidar is pointed at a specific spatial sector, the system queries a mapping table based on the current channel state level of that sector to accurately determine the target bit error rate (BER) for the current environment. For example, in a Level 3 adverse channel environment, the system retrieves the target BER as follows: To ensure basic communication reliability through strong constraints; in a Level 1 high-quality channel environment, the target bit error rate queried by the system is To ensure highly reliable communication while maximizing transmission speed.

[0029] After obtaining the target bit error rate, the system performs parameter calculations based on the hardware performance of the lidar. The system then obtains the current system signal-to-noise ratio (SNR) of the lidar (denoted as...). (Unit: dB, converted to linear value for calculation), and based on the target bit error rate obtained from the query (denoted as...). The maximum usable modulation order (denoted as ) that meets current communication reliability requirements is calculated using communication theory formulas based on the system signal-to-noise ratio and the system signal-to-noise ratio. Specifically, the theoretical constraint relationship of the bit error rate of DPIM modulation approximately satisfies: Formula (4): in, For complementary error functions, The scintillation index of the current spatial sector. It is a natural exponential function. Let L be the logarithm of the modulation order with base 2, representing the number of bits carried by each DPIM symbol. This formula is suitable for the atmospheric turbulence channel scenario targeted by this invention. Compared with the Gaussian channel formula, it can more accurately calculate the bit error rate under turbulent conditions, ensuring the rationality of the modulation order selection.

[0030] The system internally pre-sets a selectable set of modulation orders as L∈{2,4,8,16,32}, where all modulation orders are integer powers of 2, facilitating the block mapping of binary bit streams. The system then uses the current channel... , Substituting into formula (4), the selectable modulation order is calculated from largest to smallest, and the largest L value that makes the inequality true is selected as the maximum available modulation order.

[0031] This embodiment provides a specific calculation example: Signal-to-noise ratio of a lidar system. (Linearity value is 100), Light intensity scintillation index of a Class 1 high-quality channel Target bit error rate Substitute into formula (4) and iterate through the calculations: When L=32, The calculated BER ≈ 1.2e−8 > 1e−9, which does not meet the requirements; When L=16, The calculation shows that BER≈3.5e−10≤1e−9, which meets the requirements; Therefore, the maximum available modulation order under a Level 1 channel is 16.

[0032] Light intensity scintillation index of a Level 3 poor channel Target bit error rate Substitute into formula (4) and iterate through the calculations: When L=8 The calculated BER ≈ 2.1e−3 > 1e−3, which does not meet the requirements; When L=4 The calculated BER ≈ 4.2e−4 ≤ 1e−3, which meets the requirements; therefore, the maximum available modulation order under the 3rd level channel is 4.

[0033] The maximum available modulation order determines the maximum amount of information that each pulse can carry. Under the premise of ensuring that the target bit error rate is not exceeded, the system will choose the largest possible modulation order to improve transmission efficiency.

[0034] At the same time, the system also needs to consider the sensing function of the lidar. Based on the lidar's target detection range resolution requirements, the system determines the upper limit of the emitted pulse width. The lidar range resolution calculation formula is: Formula 5: in, For distance resolution, The speed of light in a vacuum. Atmospheric refractive index, This refers to the transmit pulse width. Narrower pulses provide higher range resolution.

[0035] In this embodiment, the target range resolution of the lidar is 0.15m. Substituting this into formula (5), the upper limit of the pulse width is calculated. This value represents the theoretically limiting pulse width corresponding to the distance resolution. Subsequently, the system combines the calculated maximum usable modulation order and the upper limit of the pulse width to calculate the corresponding basic time slot width through a timing mapping relationship. Specifically, to ensure that the optical pulse can be transmitted completely without causing severe crosstalk between symbols, the system sets the basic time slot width... It must be less than or equal to the upper limit of the pulse width. In actual configuration, the system directly takes... Alternatively, based on the system clock period of the lidar transmitter (1ns in this embodiment), The data is rounded down to determine the final base time slot width. In this embodiment, the base time slot width is fixed at 1 ns, consistent with the upper limit of the pulse width, ensuring that the distance resolution meets the design requirements. The base time slot width is the smallest time unit of DPIM modulation and directly affects the balance between communication rate and sensing accuracy.

[0036] Finally, the system uses the calculated maximum available modulation order and the corresponding basic time slot width as the DPIM parameters for the current spatial sector. Through this adaptive parameter determination mechanism, the system can dynamically achieve the optimal match between communication reliability and sensing resolution in different spatial sectors.

[0037] Example 5 As a preferred embodiment of the present invention, based on Embodiment 1, the bit grouping rule of the communication bit stream to be transmitted is determined according to the modulation order of the corresponding DPIM parameter, the communication bit stream to be transmitted is grouped, and the grouped communication bit stream is mapped in combination with the basic time slot width of the corresponding DPIM parameter to obtain an initial pulse sequence composed of alternating pulses and empty time slots, including: Calculate the logarithm of the modulation order of the DPIM parameter with base 2 as the target packet length, and divide the communication bit stream to be transmitted into multiple bit packets according to the target packet length; Convert each bit group from binary to decimal to obtain the decimal value corresponding to each bit group; For each bit group, a light pulse with a width equal to the base time slot width of the corresponding DPIM parameter is generated, and an empty time slot is added after the light pulse. The number of the added empty time slots is equal to the decimal value, thereby obtaining the DPIM symbol corresponding to each bit group. A fixed-width guard time slot is inserted between two adjacent DPIM symbols, and all DPIM symbols with inserted guard time slots are spliced ​​together to obtain the initial pulse sequence.

[0038] Specifically, during signal mapping, the system first determines the standard for dividing the communication bit stream based on the defined modulation order. The system calculates the logarithm of the modulation order (base 2) and uses this result as the target packet length. Where L is the modulation order. Subsequently, the system truncates the continuous communication bit stream to be transmitted into multiple fixed-length bit packets according to the calculated target packet length. If the total length of the communication bit stream is not an integer multiple of the target packet length, zeros are padded to the end of the bit stream until the total length is an integer multiple of the target packet length, ensuring that all bit packets have the same length.

[0039] For example, if the modulation order of the current spatial sector is 16, the system calculates the logarithm of 16 to the base 2, which is 4. The target packet length is then 4, and the system divides the communication bitstream into groups of 4 bits each. This embodiment provides a specific example: the communication bitstream to be transmitted is 101001100011, with a total length of 12 bits. It is divided into 3 bit groups of 4 bits each: 1010, 0110, and 0011, thus preparing data for subsequent pulse position modulation. If the bitstream to be transmitted is 1010011, with a total length of 7 bits, a 0 is added to the end, resulting in 10100110, which is then divided into two 4-bit groups.

[0040] After completing the bit grouping, the system performs numerical conversion and physical signal mapping on each bit group. The system performs an unsigned binary-to-decimal conversion on each bit group to accurately obtain the corresponding decimal value. The decimal value ranges from 0 to L-1, matching the modulation order. Next, the system generates an optical pulse for each bit group with a width equal to the defined base time slot width. The amplitude of the optical pulse is the system's rated transmission amplitude, and both the rise and fall times do not exceed 1 / 10 of the base time slot width, ensuring the integrity of the pulse's time-domain waveform and serving as the signal's start marker. Following the generation of this optical pulse, the system immediately appends a series of zero-power empty time slots. The number of these empty time slots is strictly equal to the previously obtained decimal value, and the width of each empty time slot is exactly the same as the base time slot width. In this way, the system fully carries the digital information within the number of empty time slots following the pulse (i.e., the pulse interval), thus obtaining the DPIM symbol corresponding to each bit group.

[0041] This embodiment provides a specific example of symbol generation: basic time slot width. With modulation order L=16, bit block 1010 is converted to decimal value 10, and the system will generate a 1ns wide optical pulse, followed by 10 consecutive 1ns wide space slots. The total duration of this DPIM symbol is 1×1ns + 10×1ns = 11ns. Bit block 0110 is converted to decimal value 6, which corresponds to generating a 1ns optical pulse + 6 1ns space slots, with a total symbol duration of 7ns. Bit block 0011 is converted to decimal value 3, which corresponds to generating a 1ns optical pulse + 3 1ns space slots, with a total symbol duration of 4ns.

[0042] To prevent inter-symbol interference caused by multipath effects, hardware response delays, or channel dispersion, the system also needs to protect the generated symbols. The system inserts a fixed-width guard slot between two adjacent DPIM symbols, with the guard slot width set to one base slot width (i.e., 1 ns). This ensures sufficient time interval between consecutive symbols, preventing the pulse tail of the previous symbol from affecting the pulse detection of the subsequent symbol. Finally, the system seamlessly splices all DPIM symbols with inserted guard slots in chronological order, ultimately obtaining an initial pulse sequence composed of alternating pulses and empty time slots.

[0043] This embodiment provides a complete example of initial pulse sequence splicing, such as... Figure 2As shown: The above three DPIM symbols, with 1ns guard slots inserted between adjacent symbols, have a total duration of 11ns + 1ns + 7ns + 1ns + 4ns = 24ns after splicing. The sequence structure is: [1ns pulse + 10ns empty slot] + [1ns guard slot] + [1ns pulse + 6ns empty slot] + [1ns guard slot] + [1ns pulse + 3ns empty slot]. Through the above complete process, combined with... Figure 2 The mapping process shown demonstrates how the system successfully converts the original communication bitstream into a physical pulse sequence suitable for LiDAR transmission and capable of resisting interference, effectively ensuring the generation quality of the integrated communication and sensing signal.

[0044] Example 6 As a preferred embodiment of the present invention, based on Example 1, each pulse in the initial pulse sequence is converted into a swept frequency pulse with wideband frequency variation characteristics to generate a communication sensing integrated signal corresponding to the communication bit stream to be transmitted, including: Extract the rising edge and falling edge times of each pulse in the initial pulse sequence to determine the time window of each pulse; Based on the channel state level of the currently pointed spatial sector, the corresponding nonlinear frequency modulation function is adaptively selected. The nonlinear frequency modulation function is used to control the nonlinear change of instantaneous frequency over time. Within the time window of each pulse, the laser carrier is frequency modulated using a nonlinear frequency modulation function to generate a nonlinear sweep pulse; By maintaining the empty time slots in the initial pulse sequence at zero power output, a communication sensing integrated signal corresponding to the communication bit stream to be transmitted, composed of nonlinear sweep pulses and empty time slots, is obtained.

[0045] Specifically, after acquiring the initial pulse sequence, the system needs to modify the waveform of the pulses in the sequence to enhance sensing performance. This modification process only changes the instantaneous frequency of the laser carrier, completely preserving the original pulse's rising edge, falling edge, time width, and time position in the time domain. Therefore, it does not change the pulse interval information of the DPIM symbol and will not affect the communication demodulation at the receiving end. The system first performs time-domain analysis on the initial pulse sequence, accurately extracting the rising edge time (the moment when the amplitude reaches 10% of the rated amplitude) and falling edge time (the moment when the amplitude drops to 10% of the rated amplitude) of each pulse in the initial pulse sequence through an edge detection algorithm. By calculating the difference between the rising edge time and the falling edge time, the system can accurately determine the time window of each pulse and the width of the pulse time window. With base time slot width The timing of the modulated sweep pulses is completely equal to that of the DPIM symbols, ensuring a perfect match. This time window defines the effective time range for subsequent frequency modulation operations.

[0046] Subsequently, the system obtains the channel state level of the currently pointed spatial sector and adaptively selects the parameters of the corresponding nonlinear frequency modulation function based on the channel state level of the currently pointed spatial sector. The nonlinear frequency modulation function is used to control the nonlinear change of instantaneous frequency over time. Specifically, the system adopts a nonlinear frequency modulation mathematical model based on the tangent function, whose instantaneous frequency... The expression is: Formula (6): In order to adapt to the positive time series of DPIM pulses, the time variable is modified to t∈[0,T], where T is the width of the pulse time window (i.e. the basic time slot width). The center frequency of the laser carrier is used in this embodiment. (Corresponding to the 1550nm communication band) In this embodiment, the sweep bandwidth is set to 2GHz, corresponding to a range resolution of 0.075m for the lidar, which meets the design requirements. An adjustment factor to control the degree of nonlinearity.

[0047] The system adaptively adjusts according to the channel state level. The values ​​can be selected, and the specific mapping rules are shown in the table below: In a Level 3 adverse channel sector with low channel status and severe Doppler shift interference, the system selects a larger... The value of this value makes the nonlinear frequency modulation function exhibit a slow rate of change at both ends and a sharp rate of change in the middle, thereby effectively suppressing the increase in range sidelobes caused by Doppler shift, thus improving the signal's anti-interference capability and velocity measurement accuracy in complex environments; while in the high-quality channel sector of level 1 with a higher channel state level, the system selects a smaller value. The value is adjusted so that its instantaneous frequency change approaches that of conventional linear frequency modulation, maximizing bandwidth utilization.

[0048] After determining the modulation function and time range, the system enters the physical signal generation stage. Within the time window of each pulse, the system uses a selected nonlinear frequency modulation function to modulate the laser carrier frequency. Frequency modulation is achieved through an electro-optic modulator at the lidar transmitter, with a modulation bandwidth of no less than 3 GHz to meet the sweep bandwidth requirement. During this process, the laser carrier frequency no longer remains constant but changes continuously within the time window according to the rule set by the nonlinear frequency modulation function, thereby generating nonlinear sweep pulses.

[0049] This embodiment provides a specific example of frequency modulation: basic time slot width Pulse time window width Level 3 poor channel conditions Laser carrier center frequency Sweep bandwidth Substituting into formula (6), we get: at t=0, At t=0.5ns, At t=1ns, Within a 1ns pulse time window, the instantaneous frequency of the laser carrier increases from 193.409THz to 193.411THz in a nonlinear sweep, with a total sweep bandwidth of 2GHz. This transforms the original single-frequency pulse into a sweep pulse with broadband frequency variation characteristics, significantly improving the range resolution of the lidar while completely preserving the time-domain edges of the original pulse, without affecting the detection of DPIM symbols.

[0050] While processing all pulses, the system also needs to strictly control the no-signal portion of the initial pulse sequence. The system maintains zero-power output in both the empty time slots and guard time slots of the initial pulse sequence, ensuring that the laser does not emit any energy during the pulse-free periods. This approach not only reduces the overall power consumption of the system but also avoids background noise interference at the communication receiver. Finally, the system combines the frequency-modulated pulses with the zero-power empty and guard time slots according to their original timing sequence to obtain the integrated communication sensing signal corresponding to the communication bit stream to be transmitted, composed of nonlinear swept pulses and empty time slots. Its timing structure is as follows: Figure 3 As shown. Through the above process, combined with Figure 3 The waveform characteristics shown demonstrate that the system successfully integrates the pulse position information from digital communication with the broadband sweep waveform from radar sensing, achieving efficient sharing of communication and sensing functions on the same physical signal.

[0051] Example 7 like Figure 4 As shown, a DPIM-based integrated signal generation system for lidar communication and sensing includes: The signal acquisition and feature extraction module is used to acquire optical echo signals at different spatial pointing angles generated by the lidar scanning and detecting the target space, and to extract the channel fading characteristic parameters of the optical echo signals. The sector partitioning module is used to calculate the atmospheric turbulence intensity index under the corresponding spatial pointing angle based on the channel fading characteristic parameters, and to divide the target space into multiple spatial sectors with different channel state levels according to the atmospheric turbulence intensity index. The parameter determination module is used to obtain the communication bit stream to be sent when performing a communication task for the currently pointed spatial sector, and determine the corresponding DPIM parameters according to the channel state level of the currently pointed spatial sector. The DPIM parameters include the modulation order and the basic time slot width. The sequence mapping module is used to determine the bit grouping rules of the communication bit stream to be transmitted according to the modulation order of the corresponding DPIM parameter, group the communication bit stream to be transmitted, and map the grouped communication bit stream in combination with the basic time slot width of the corresponding DPIM parameter to obtain an initial pulse sequence composed of alternating pulses and empty time slots. The signal generation module is used to convert each pulse in the initial pulse sequence into a swept frequency pulse with wideband frequency variation characteristics, thereby generating a communication sensing integrated signal corresponding to the communication bit stream to be transmitted.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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 method for generating integrated communication and sensing signals for lidar based on DPIM, characterized in that, The method includes: Acquire optical echo signals at different spatial pointing angles generated by lidar scanning and detecting the target space, and extract the channel fading characteristic parameters of the optical echo signals; The atmospheric turbulence intensity index is calculated based on the channel fading characteristic parameters at the corresponding spatial pointing angle, and the target space is divided into multiple spatial sectors with different channel state levels according to the atmospheric turbulence intensity index. When performing a communication task for the currently pointed spatial sector, the communication bit stream to be sent is obtained, and the corresponding DPIM parameters are determined according to the channel state level of the currently pointed spatial sector. The DPIM parameters include the modulation order and the basic time slot width. The bit grouping rule of the communication bit stream to be transmitted is determined according to the modulation order of the corresponding DPIM parameter. The communication bit stream to be transmitted is grouped and mapped according to the basic time slot width of the corresponding DPIM parameter to obtain an initial pulse sequence composed of alternating pulses and empty time slots. Each pulse in the initial pulse sequence is converted into a swept frequency pulse with wideband frequency variation characteristics to generate a communication sensing integrated signal corresponding to the communication bit stream to be transmitted.

2. The method for generating integrated LiDAR communication and sensing signals based on DPIM according to claim 1, characterized in that, The extracted channel fading characteristic parameters of the optical echo signal include: Envelope detection and low-pass filtering are performed on the optical echo signal to obtain the slowly varying envelope signal of the optical intensity; Calculate the light intensity variance and light intensity mean of the slowly varying envelope signal within a preset time window, and use the ratio of the light intensity variance to the square of the light intensity mean as the light intensity scintillation index. Autocorrelation analysis is performed on the slowly varying envelope signal to obtain the time delay corresponding to the decrease of the autocorrelation function to a preset percentage of the peak value, which is used as the channel coherence time. By combining the light intensity scintillation index and the channel coherence time, channel fading characteristic parameters are constructed.

3. The method for generating integrated LiDAR communication and sensing signals based on DPIM according to claim 2, characterized in that, The atmospheric turbulence intensity index is calculated based on the channel fading characteristic parameters at the corresponding spatial pointing angle, and the target space is divided into multiple spatial sectors with different channel state levels according to the atmospheric turbulence intensity index, including: The weighting coefficients corresponding to different channel fading characteristic parameters are obtained, and the light intensity scintillation index and channel coherence time are weighted and fused to obtain the atmospheric turbulence intensity index under the corresponding spatial pointing angle. The atmospheric turbulence intensity indices under all spatial pointing angles in the target space are constructed into a one-dimensional dataset, and the K-means clustering algorithm is used to perform cluster analysis on the one-dimensional dataset to obtain multiple cluster centers; Based on the size relationship of each cluster center, a corresponding channel state level is assigned to each cluster. Scanning regions belonging to the same cluster and with adjacent spatial pointing angles are merged to generate multiple spatial sectors with different channel state levels.

4. The method for generating integrated LiDAR communication and sensing signals based on DPIM according to claim 1, characterized in that, The step of determining the corresponding DPIM parameters based on the channel state level of the currently pointed spatial sector includes: A mapping table between channel state levels and target bit error rates is pre-constructed, and the corresponding target bit error rate is obtained by querying the channel state level of the currently pointed spatial sector. Based on the target bit error rate and the system signal-to-noise ratio of the lidar, calculate the maximum usable modulation order that meets the communication reliability requirements; Based on the sensing distance resolution requirements of the lidar, the upper limit of the pulse width is determined, and the corresponding basic time slot width is calculated in combination with the maximum available modulation order; The maximum available modulation order and the corresponding basic time slot width are used as the DPIM parameters for the current spatial sector.

5. The method for generating integrated LiDAR communication and sensing signals based on DPIM according to claim 1, characterized in that, The step involves determining the bit grouping rule of the communication bit stream to be transmitted based on the modulation order of the corresponding DPIM parameters, grouping the communication bit stream to be transmitted into groups, and mapping the grouped communication bit stream to the basic time slot width of the corresponding DPIM parameters to obtain an initial pulse sequence composed of alternating pulses and empty time slots, including: Calculate the logarithm of the modulation order of the DPIM parameter with base 2 as the target packet length, and divide the communication bit stream to be transmitted into multiple bit packets according to the target packet length; Convert each bit group from binary to decimal to obtain the decimal value corresponding to each bit group; For each bit group, a light pulse with a width equal to the base time slot width of the corresponding DPIM parameter is generated, and an empty time slot is added after the light pulse. The number of the added empty time slots is equal to the decimal value, thereby obtaining the DPIM symbol corresponding to each bit group. A fixed-width guard time slot is inserted between two adjacent DPIM symbols, and all DPIM symbols with inserted guard time slots are spliced ​​together to obtain the initial pulse sequence.

6. The method for generating integrated LiDAR communication and sensing signals based on DPIM according to claim 1, characterized in that, The step of converting each pulse in the initial pulse sequence into a swept-frequency pulse with wideband frequency variation characteristics to generate a communication sensing integrated signal corresponding to the communication bit stream to be transmitted includes: Extract the rising edge and falling edge times of each pulse in the initial pulse sequence to determine the time window of each pulse; Based on the channel state level of the currently pointed spatial sector, the corresponding nonlinear frequency modulation function is adaptively selected. The nonlinear frequency modulation function is used to control the nonlinear change of instantaneous frequency over time. Within the time window of each pulse, the laser carrier is frequency modulated using a nonlinear frequency modulation function to generate a nonlinear sweep pulse; By maintaining the empty time slots in the initial pulse sequence at zero power output, a communication sensing integrated signal corresponding to the communication bit stream to be transmitted, composed of nonlinear sweep pulses and empty time slots, is obtained.

7. A DPIM-based integrated signal generation system for lidar communication and sensing, characterized in that, The system includes: The signal acquisition and feature extraction module is used to acquire optical echo signals at different spatial pointing angles generated by the lidar scanning and detecting the target space, and to extract the channel fading characteristic parameters of the optical echo signals. The sector partitioning module is used to calculate the atmospheric turbulence intensity index under the corresponding spatial pointing angle based on the channel fading characteristic parameters, and to divide the target space into multiple spatial sectors with different channel state levels according to the atmospheric turbulence intensity index. The parameter determination module is used to obtain the communication bit stream to be sent when performing a communication task for the currently pointed spatial sector, and determine the corresponding DPIM parameters according to the channel state level of the currently pointed spatial sector. The DPIM parameters include the modulation order and the basic time slot width. The sequence mapping module is used to determine the bit grouping rules of the communication bit stream to be transmitted according to the modulation order of the corresponding DPIM parameter, group the communication bit stream to be transmitted, and map the grouped communication bit stream in combination with the basic time slot width of the corresponding DPIM parameter to obtain an initial pulse sequence composed of alternating pulses and empty time slots. The signal generation module is used to convert each pulse in the initial pulse sequence into a swept frequency pulse with wideband frequency variation characteristics, thereby generating a communication sensing integrated signal corresponding to the communication bit stream to be transmitted.

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