MIMO radar reactance detection excitation signal generation method

Abstract

The invention discloses an MIMO radar reactance detection excitation signal generation method. In the method, detection data are grouped, and the group comprises a habit pulse mapping frame, an hbbit transmission sequence frame, an hcbit keying selection frame and an hdbit antenna control frame; and according to a one-to-one mapping relationship, through pulse mapping, transmission sequence determination, keying selection and antenna selection, data packets are loaded to pulses to form radar reactance detection excitation signals. According to the technical scheme disclosed by the invention, the data transmission efficiency of the excitation signal is improved, the peak-to-average ratio is reduced, and the power utilization rate of the system is improved.

Description

Technical Field

[0001] This invention relates to the field of radar, and more particularly to a method for generating excitation signals for reactance detection in MIMO radar. Background Technology

[0002] Radar is an electronic device that uses electromagnetic waves to detect and locate targets. It emits electromagnetic waves to illuminate a target and receives its echo, thereby obtaining information such as the distance from the target to the electromagnetic wave emission point, the rate of change of distance (radial velocity), azimuth, and altitude. The advent of Integrated Pulse Aperture Radar (SIAR) and the development of Multiple-Input Multiple-Output (MIMO) technology in the communications field led to the emergence of MIMO radar. MIMO radar applies MIMO technology and space-time coding to radar systems. Compared to traditional PAR, MIMO radar exhibits superior performance in target parameter estimation, detection and identification, and tracking. For MIMO radar, in most cases, the transmitted signals must be independent. Mathematically, this requires that the waveforms be orthogonal, thus forming a wide transmission beam. This is the essential difference in signal form between MIMO and traditional phased array and bistatic / multistatic radars. Radar reactance testing refers to the testing of the basic electrical parameters, detection performance, and related characteristic parameters of radar equipment during the research, development, production, and use of the equipment. This testing provides a basis for performance evaluation, ensuring the smooth progress of radar development, effectively shortening development time, and improving equipment efficiency. With the rapid development of integrated radar and navigation design, higher requirements have been placed on the generation of excitation signals. In order to adapt to complex electromagnetic environments, expand the instantaneous dynamic range of receivers, and enhance the ability to extract small targets, excitation signals are required to have higher performance in terms of data transmission capability and power utilization efficiency.

[0003] In existing technologies, there are two main types of excitation signal design. One type involves loading a linear frequency modulated (LFM) signal after BPSK or MSK modulation and combining it with the radar signal to form the excitation signal. The advantages of this method are: constant signal envelope, long detection range, and high system power efficiency. The disadvantage is: low data transmission capability, making it suitable only for low-speed systems. The other type is based on OFDM-based excitation signal waveform design, utilizing the high spectral efficiency of OFDM modulation to improve data transmission rate. The advantages of this method are: strong data transmission capability, suitability for high-speed systems, large time-bandwidth product, and high target resolution. The disadvantage is: the signal has a high peak-to-average power ratio (PAPR), leading to a significant decrease in system power efficiency, thus reducing target detection performance.

[0004] Therefore, how to improve the data transmission capability of the excitation signal, while reducing the peak-to-average power ratio of the excitation signal, and improving the power utilization and detection capability of the system, is a difficult problem that needs to be solved in the generation of excitation signals for reactive detection in existing MIMO radars. Summary of the Invention

[0005] The purpose of this invention is to disclose a technical solution that improves the data transmission capability of the excitation signal, while reducing the peak-to-average power ratio of the excitation signal, thereby improving the power utilization and detection capability of the system.

[0006] To achieve the objectives of this invention, a method for generating an excitation signal for MIMO radar reactance detection is provided. This method includes the following steps:

[0007] Step 1: Group the detection data, the grouping including h a bit pulse mapping frame, h b bit transmission sequence frame, h c Bit keying selects frames and h d bit antenna control frame;

[0008] Step 2: Generate a pulse set, which contains N time-domain orthogonal pulses;

[0009] Step 3: Perform pulse mapping: According to the one-to-one mapping relationship, map the h... a Each data combination of the bit pulse mapping frame is respectively mapped to select M pulses from the pulse set for transmitting data packets;

[0010] Step 4: Determine the transmission order: According to the one-to-one mapping relationship, transfer the h... b Each data combination of the bit transmission sequence frame is mapped to the h. a The sequence of serial transmission of M pulses mapped by the bit pulse mapping frame.

[0011] Step 5: Carrier modulation: Amplitude modulation is used to multiply the M pulses confirming the transmission order by a sinusoidal carrier signal to form a carrier signal;

[0012] Step Six: Perform keying selection: based on the h c Bit keying selects the state of each data bit in the frame, and controls the keying switch state of the M pulse carrier modulation signals respectively, forming a radar reactance detection excitation signal. In the i-th repetition frequency period, the excitation signal is:

[0013] When (i-1)T s <t≤(i-1)T s +T c hour,

[0014]

[0015] When (i-1)T s +T c <t≤(i-1)T s +2T c hour,

[0016]

[0017] …,

[0018] When (i-1)T s +(j-1)T c <t≤(i-1)T s +jT c hour,

[0019]

[0020] …,

[0021] When (i-1)T s +(M-1)T c <t≤(i-1)T s +MT c hour,

[0022]

[0023] When (i-1)T s +MT c <t≤iT s At that time, s i (t) = 0;

[0024] Among them, a1, a2, ..., a j ... a M Each represents the h c Bit keying selects each bit of data in a frame. The M pulses, T, represent the confirmation of the transmission order. s T represents the repetition frequency period. c ω represents the pulse period. c Indicates the carrier angular frequency;

[0025] Step 7: Perform antenna selection control: According to the one-to-one mapping relationship, select the h... d Each data combination of the bit antenna control frame is mapped to selecting W antennas from K antennas for radiation.

[0026] Furthermore, in the technical solution disclosed in this invention, the h c Bit keying selects the number of data bits per frame (h) cThe relationship between the number of pulses M used to transmit data packets and the pulse number M is as follows:

[0027] h c =M.

[0028] Furthermore, in the technical solution disclosed in this invention, the h d The number of data bits in the bit antenna control frame h d The number of antennas K and the number of antennas W selected for radiation satisfy the following relationship:

[0029]

[0030] Preferably, in the technical solution disclosed in this invention, the grouping includes a 2-bit pulse mapping frame, a 2-bit transmission sequence frame, a 3-bit keying selection frame, and a 2-bit antenna control frame.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) Improved data transmission capability

[0033] In the technical solution disclosed in this invention, the traditional method of loading detection data using only amplitude parameters is abandoned. Instead, the method of loading data using excitation signals is expanded. Four methods are used simultaneously to load data: pulse mapping, pulse sequence selection, keying selection, and antenna control. This effectively improves the utilization rate of pulse waveforms and thus enhances the data transmission capability of the system.

[0034] (2) Improved power utilization

[0035] In the technical solution disclosed in this invention, the pulses used to transmit data packets are transmitted serially, avoiding the peak-to-average power ratio (PAPR) characteristic caused by multi-carrier technology, thereby reducing the PAPR of the excitation signal and enabling the power amplifier system to operate in the linear operating region. Therefore, compared with the prior art, the power utilization rate of the system can be effectively improved.

[0036] Other advantages and features of the present invention will be apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0038] In existing technologies, there are two main types of excitation signal design. One type involves loading a linear frequency modulated signal (LFM) after BPSK or MSK modulation, and then combining it with radar or reactive signals to form the excitation signal. The advantages of this method are: constant signal envelope, long detection range, and high system power efficiency; the disadvantage is: low data transmission capability, making it suitable only for low-speed systems. The other type is based on OFDM excitation signal design, utilizing the high spectral efficiency of OFDM modulated signals to improve data transmission rate. The advantages of this method are: strong data transmission capability, suitability for high-speed systems, and high target resolution; the disadvantage is: the signal has a high peak-to-average power ratio (PAPR), leading to a significant decrease in system power efficiency, thereby reducing target detection performance.

[0039] Therefore, in existing technologies, excitation signal design methods struggle to simultaneously achieve both high data transmission and low peak-to-average power ratio (PAPR). Typically, one aspect of performance must be sacrificed to gain the other, making it difficult to achieve a balance between both. In current radar and communication fields, data transmission is limited to loading data through parameters such as the amplitude, frequency, and phase of pulse waveforms, significantly restricting the potential for improvement due to limitations imposed by the information loading method.

[0040] To address this problem, this invention discloses a method for generating an excitation signal for MIMO radar reactance detection. This method includes the following steps:

[0041] Step 1: Group the detection data, the grouping including h a bit pulse mapping frame, h b bit transmission sequence frame, h c Bit keying selects frames and h d bit antenna control frame;

[0042] Step 2: Generate a pulse set, which contains N time-domain orthogonal pulses;

[0043] Step 3: Perform pulse mapping: According to the one-to-one mapping relationship, map the h... a Each data combination of the bit pulse mapping frame is respectively mapped to select M pulses from the pulse set for transmitting data packets;

[0044] Step 4: Determine the transmission order: According to the one-to-one mapping relationship, transfer the h... b Each data combination of the bit transmission sequence frame is mapped to the h. a The sequence of serial transmission of M pulses mapped by the bit pulse mapping frame.

[0045] Step 5: Carrier modulation: Amplitude modulation is used to multiply the M pulses confirming the transmission order by a sinusoidal carrier signal to form a carrier signal;

[0046] Step Six: Perform keying selection: based on the h c Bit keying selects the state of each data bit in the frame, and controls the keying switch state of the M pulse carrier modulation signals respectively, forming a radar reactance detection excitation signal. In the i-th repetition frequency period, the excitation signal is:

[0047] When (i-1)T s <t≤(i-1)T s +T c hour,

[0048]

[0049] When (i-1)T s +T c <t≤(i-1)T s +2T c hour,

[0050]

[0051] …,

[0052] When (i-1)T s +(j-1)T c <t≤(i-1)T s +jT c hour,

[0053]

[0054] …,

[0055] When (i-1)T s +(M-1)T c <t≤(i-1)T s +MT c hour,

[0056]

[0057] When (i-1)T s +MT c <t≤IT s At that time, s i (t) = 0;

[0058] Among them, a1, a2, ..., a j ... a M Each represents the h c Bit keying selects each bit of data in a frame. The M pulses, T, represent the confirmation of the transmission order. s T represents the repetition frequency period. c ω represents the pulse period. c Indicates the carrier angular frequency;

[0059] Step 7: Perform antenna selection control: According to the one-to-one mapping relationship, select the h... d Each data combination of the bit antenna control frame is mapped to selecting W antennas from K antennas for radiation.

[0060] In this embodiment of the invention, the inventors abandoned the traditional method of loading data using parameters and expanded the ways to load data using pulse waveforms. A multi-parameter mapping method is used to load data. This multi-parameter mapping method includes four modes: pulse mapping, pulse sequence selection, keying selection, and antenna control.

[0061] Furthermore, in this embodiment of the invention, pulse mapping involves selecting a portion of pulse waveforms from multiple pulse waveforms to transmit data, utilizing the diversity of pulse waveform combinations generated by pulse waveform selection to transmit data, that is, mapping the combined state of multi-bit data to a pulse waveform combination. Pulse sequence selection refers to using the diversity of pulse order in serial transmission to carry data when multiple pulse waveforms are transmitted serially, mapping the combined state of multi-bit data to a pulse transmission order combination; keying selection refers to mapping the state of data bits to the keying state of the modulation signal; antenna control refers to selecting a portion of antennas from multiple antennas for radiation, utilizing the diversity of antenna combinations generated by antenna selection to represent data, that is, mapping the combined state of multi-bit data to an antenna combination. In this way, the four parameters of pulse mapping, pulse transmission order, keying selection, and antenna control can be fully utilized to carry data simultaneously, thereby improving the data transmission efficiency of pulse waveforms. Furthermore, in order to reduce the peak-to-average power ratio (PAPR) of the excitation signal, this invention abandons the method of time-domain superposition of multiple pulse waveforms, and uses a serial transmission method for pulse waveforms to reduce the PAPR of the excitation signal, improve the power utilization of the system, and thus improve the detection performance. Furthermore, the pulse waveform employs a serial transmission method, which not only reduces the peak-to-average power ratio (PAPR) of the signal but also effectively reduces inter-symbol interference (ISI) between pulses, thereby improving the reliability of signal transmission. Therefore, the technical solution disclosed in this invention is beneficial for improving the system's data transmission performance, power amplifier performance, and detection capabilities.

[0062] Furthermore, in the technical solutions disclosed in the embodiments of the present invention, the h a The number of data bits in the bit pulse mapping frame h a The relationship between the number of time-domain orthogonal pulses N contained in the pulse set and the number of pulses M selected for transmitting data packets is as follows:

[0063]

[0064] in, This constraint relation makes h a The number of data combinations in a bit pulse mapping frame is less than or equal to the number of combinations of selecting M pulses from N pulses. This enables a one-to-one mapping between data combinations and pulse selection combinations, avoiding ambiguity in the mapping between data combinations and pulse selection combinations.

[0065] Furthermore, in the technical solutions disclosed in the embodiments of the present invention, the h b The number of data bits in the bit transmission sequence frame h b The relationship between the number of sequential combinations of M pulses in serial transmission and the following formula is satisfied:

[0066]

[0067] in, This constraint relationship makes h b The number of data combinations in a bit transmission sequence frame is less than or equal to the number of permutations of M pulse serial transmission sequences, thus enabling a one-to-one mapping between data combinations and permutations of pulse serial transmission sequences, avoiding ambiguity in the mapping between data combinations and pulse serial transmission sequences.

[0068] Furthermore, in the technical solutions disclosed in the embodiments of the present invention, the h c Bit keying selects the number of data bits per frame (h) c The relationship between h and the number of pulses M used to transmit data packets is: c =M. This constraint relationship makes h c The number of data bits in the bit keying selection frame is equal to the number of modulation signal keying bits, thus enabling a one-to-one mapping between data combinations and modulation signal keying.

[0069] Furthermore, in the technical solutions disclosed in the embodiments of the present invention, the h d The number of data bits in the bit antenna control frame h d The number of antennas K and the number of antennas W selected for radiation satisfy the following relationship:

[0070]

[0071] in, This constraint relation makes h d The number of data combinations in a bit antenna control frame is less than or equal to the number of combinations of selecting W antennas from K antennas. This enables a one-to-one mapping between data combinations and antenna selection combinations, avoiding ambiguity in the mapping between data combinations and antenna selection combinations.

[0072] To better enable those skilled in the art to understand the embodiments of the present invention, examples are provided below. Typically, in the technical solutions disclosed in the embodiments of the present invention, each pulse set contains four time-domain orthogonal pulses, and there are four transmit antennas. The detection data is divided into multiple data groups in 9-bit units, and each 9-bit data group includes a 2-bit pulse mapping frame, a 2-bit transmission sequence frame, a 3-bit keying selection frame, and a 2-bit antenna control frame.

[0073] Pulse mapping is performed according to pulse mapping rules. Following a one-to-one mapping relationship, each data combination of the 2-bit pulse mapping frame is mapped to three pulses selected from four pulses in the pulse set for data transmission. The pulse set includes four pulse waveforms, denoted as follows: Then, according to the pulse mapping rule, three pulses are selected from the four pulse waveforms in the pulse set for data transmission. At this point, there are a total of... A pulse combination state. Typically, a 2-bit pulse mapping frame data combination of 00 is mapped to a pulse selected from 4 pulses as follows: The data combination 01 is mapped to a pulse selected from 4 pulses. Data combination 10 is mapped to a pulse selected from 4 pulses. Data combination 11 is mapped to a pulse selected from 4 pulses. Assuming the current data combination of the 2-bit pulse mapping frame is 00, then the mapping is to select a pulse from the 4 pulses as follows: Used for transmitting data.

[0074] The pulse serial transmission order is determined according to the transmission order mapping rule. Following a one-to-one mapping relationship, each data combination of the 2-bit transmission order frame is mapped to... The serial transmission sequence of a pulse; according to the formula for the number of permutations, the number of permutations can be calculated. The constraints are met: Typically, a 2-bit transmission sequence frame of data, consisting of 00 bits, is mapped to a serial transmission sequence of... Data combination 01 is mapped to serial transmission sequence as follows Data combination 10 is mapped to a serial transmission sequence of: Data combination 11 is mapped to a serial transmission sequence of: Other serial transmission sequence combinations were not adopted. Assuming the current data combination of the 2-bit transmission sequence frame is 01, the mapped serial transmission sequence is:

[0075] According to the keying selection rules, control is performed based on the data state of each bit in the 3-bit keying selection frame. The keying switch states of these three pulse carrier modulation signals form the radar reactance detection excitation signal. When the data bit state in the 3-bit keying selection frame is 1, the keying state is transmit; when the data bit state is 0, the keying state is not transmit. Assuming the current data in the 3-bit keying selection frame is 101, the excitation signal in the i-th repetition frequency period is:

[0076] When (i-1)T s <t≤(i-1)T s +T c hour,

[0077]

[0078] When (i-1)T s +T c <t≤(i-1)T s +2T c hour,

[0079] s i (t) = 0,

[0080] When (i-1)T s +2T c <t≤(i-1)T s +3T c hour,

[0081]

[0082] When (i-1)T s +3T c <t≤iT s At that time, s i (t) = 0.

[0083] According to the antenna selection control rules and a one-to-one mapping relationship, each data combination of the 2-bit antenna control frame is mapped to selecting 3 antennas from 4 antennas for radiation. These 4 transmitting antennas are denoted as Antenna 1, Antenna 2, Antenna 3, and Antenna 4. Therefore, according to the antenna selection control rules, 3 antennas are selected from the 4 transmitting antennas for signal transmission. At this point, there are a total of... The antenna combination states are as follows. Typically, data combination 00 in a 2-bit antenna control frame maps to the antenna combination selected from the four transmit antennas: Antenna 1, Antenna 2, and Antenna 3; data combination 01 maps to the antenna combination selected from the four transmit antennas: Antenna 1, Antenna 2, and Antenna 4; data combination 10 maps to the antenna combination selected from the four transmit antennas: Antenna 2, Antenna 3, and Antenna 4; and data combination 11 maps to the antenna combination selected from the four transmit antennas: Antenna 1, Antenna 3, and Antenna 4. Assuming the current data combination of the 2-bit antenna control frame is 00, then the antenna combination selected from the four transmit antennas, Antenna 1, Antenna 2, and Antenna 3, is used for transmitting signals.

[0084] According to the above rules, when the 9-bit data block of the detection data is 000110100, the corresponding mapping state is shown in Table 1.

[0085] Table 1. Examples of data grouping mapping states

[0086]

[0087] In the technical solutions disclosed in the embodiments of the present invention, the correspondence between pulse mapping, pulse transmission order, keying selection and antenna selection and mapping state is not limited to Table 1, as long as a one-to-one mapping can be satisfied.

[0088] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be readily implemented by those skilled in the art. Therefore, the present invention is not limited to the specific details without departing from the general concept defined by the claims and their equivalents.

Claims

1. A method for generating an excitation signal for MIMO radar reactive detection, characterized in that The generating the excitation signal comprises the following steps: Step one: Grouping the test data, the grouping comprising h a bit pulse mapping frames, h b bit transmission order frames, h c bit keying selection frames, and h d bit antenna control frames; Step two: generating a pulse set, the pulse set contains N time domain orthogonal pulses; Step three: pulse mapping: according to one-to-one mapping relationship, each data combination of the h a bit pulse mapping frame is respectively mapped to M pulses selected from the pulse set for transmitting data packet; Step four: determining the transmission order: according to a one-to-one mapping relationship, each data combination of the h b bit transmission order frame is respectively mapped to a certain serial transmission order of M pulses mapped by the h a bit pulse mapping frame; Step five: carrier modulation: using amplitude modulation, multiplying the M pulses of the confirmation transmission sequence with a sinusoidal carrier signal respectively to form a carrier signal; Step six: Key selection: according to the h c bit key selection frame of each bit data state, the key switch state of the M pulse carrier modulation signal is controlled respectively, the radar reactance detection excitation signal is formed, and the excitation signal is: when (i-1)T s t ≤ (i-1)T s + T c when when (i-1)T s + T c < t ≤ (i-1)T s + 2T c when …， when (i-1)T s +(j-1)T c < t ≤ (i-1)T s + jT c then, …， when (i-1)T s +(M-1)T c t ≤ (i-1)T s + MT c then, when (i - 1)T s + MT c < t < iT s s i (t) = 0; wherein a1, a2,..., a j ,..., a M respectively represent the h c bit keying selection frame, respectively represent the M pulses of the confirmation transmission sequence, T s represents the repetition frequency period, T c represents the pulse period, ω c represents the carrier angular frequency; Step seven: antenna selection control is performed: each data combination of the h d bit antenna control frame is respectively mapped to select W antennas from K antennas for radiation according to a one-to-one mapping relationship.

2. The MIMO radar reactive detection excitation signal generation method of claim 1, wherein, The h c The number of data bits h of the frame selected by the bit keying c Both the number of pulses M used to transmit the data packet and the number of data bits h satisfy the relationship: h c = M.

3. The MIMO radar reactive detection excitation signal generation method of claim 1, wherein, The h d The data bit number h of the antenna control frame d The number of antennas K and the number of antennas selected for radiation W satisfy the relationship:

4. The MIMO radar reactive detection excitation signal generation method of claim 1, wherein, The packet includes a 2bit pulse mapping frame, a 2bit transmission sequence frame, a 3bit key selection frame and a 2bit antenna control frame.

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