CN114978432B - Rate adaptive modulation method for radar communication integration - Google Patents
Rate adaptive modulation method for radar communication integration Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
- H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/715—Interference-related aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
- H04L1/0013—Rate matching, e.g. puncturing or repetition of code symbols
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
- H04L1/0056—Systems characterized by the type of code used
- H04L1/0061—Error detection codes
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
- H04L1/0056—Systems characterized by the type of code used
- H04L1/0071—Use of interleaving
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/715—Interference-related aspects
- H04B2001/7152—Interference-related aspects with means for suppressing interference
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a rate self-adaptive modulation method for radar communication integration, and relates to the field of radar communication integration modulation methods. In the method, user data is RS-encoded, interleaved and then grouped, wherein the grouping comprisespBit map set sumqA bit modulation group; based on long spherical wave function generationNA transmission waveform for loading data; according to the mapping relation, each data combination of the mapping group is respectively mapped to be the slave data combinationNSelected from the transmission waveformqA waveform combination consisting of a plurality of transmission waveforms; using waveform amplitude modulation, modulating saidqEach bit of the bit modulation group is loaded to the bit modulation groupqOn a transmit waveform; the RS encoding method, the waveform combination and the data packet size are dynamically adjusted along with the change of the channel interference detection value. The technical scheme disclosed by the invention improves the spectrum efficiency and the anti-interference capability of the modulation signal, and the transmission rate can be adaptively changed along with the channel quality.
Description
Technical Field
The invention relates to the field of radar communication integrated modulation methods, in particular to a rate adaptive modulation method for radar communication integration.
Background
In the existing modulation method in the field of radar communication integration, information modulation is usually realized by one or a combination of three parameters of amplitude, frequency or phase of sine and cosine carrier waves, which also limits the exploration space for improving the frequency spectrum utilization rate in the communication field to a certain extent. Further, in the prior art, OFDM has a high spectrum utilization rate, so that it is widely used in the field of radar communication integration. The essence of the OFDM technology is to modulate information by a plurality of subcarriers that are orthogonal by two and whose frequency spectrums are overlapped by 50% to save frequency spectrum resources. However, the high sidelobe amplitude and the high peak-to-average power ratio of the OFDM reduce the power utilization efficiency of the system, and also limit the OFDM in some application scenarios.
For the field of radar communication integration, whether smooth transmission of an integrated modulation signal can be ensured in a complex electromagnetic environment is a problem which needs to be mainly solved. In order to improve the reliability of information transmission, a channel coding technique with strong error correction capability is usually adopted to reduce the error rate, the method usually trades the effectiveness of the system for reliability, and the coding method with strong error correction capability improves the reliability of information transmission and simultaneously reduces the information transmission rate of the system. The transmission channel environment is constantly changing, however, in the prior art, the adopted error correction coding mode is not changed, and the data transmission rate of the system is also not changed, which is obviously unreasonable.
Therefore, how to further improve the spectrum utilization rate of the system, and the data transmission rate can be adapted to the channel environment, is a difficult problem to be solved in the existing radar communication integration field.
Disclosure of Invention
The invention aims to disclose a rate adaptive modulation method for radar communication integration, so as to further improve the frequency spectrum utilization rate of a system.
In order to achieve the purpose of the invention, the invention provides a rate adaptive modulation method for radar communication integration. In the method, in the first stepkThe radar communication integrated modulation signal in each data code element period is as follows:
wherein the content of the first and second substances,f c is the carrier frequency and is,a j (t) Is as followsjThe bits are used for waveform amplitude modulated data to be transmitted,qis a positive integer and represents the number of radar communication integrated transmission waveforms participating in waveform amplitude modulation,ξ j (c,t) Is as followsjA transmission waveform for waveform amplitude modulation,cis a time-bandwidth product factor;
the design method of the radar communication integrated transmission waveform comprises the following steps: according to the sequence of the energy accumulation of the frequency domain from big to smallNEven order or odd order long spherical wave function; respectively intercepting the long spherical surface wave function according to the frequency spectrum symmetry of the long spherical surface wave functionNHalf frequency spectrums of even-order or odd-order long spherical wave functions are converted into time-domain waveforms according to the conversion relation from the frequency domain to the time domainξ j (c,t)，j=1，2，…，NForm aNA transmission waveform for integration of radar communication, saidqAndNthe relationship of (1) is:qis greater than or equal to 1 and less thanNIs a positive integer of (1).
Further, in the technical solution disclosed in the present invention, generating the modulation signal includes the steps of:
the method comprises the following steps: data to be transmitted by a userD(t) After RS encoding, encoded data is formedK(t)；
Step two: the coded dataK(t) Interleaving by an interleaving method to generate an interleaved signalZ(t)；
Step three: interleaving the signalZ(t) Performing a grouping, the grouping comprisingpBit map setY(t)=
Andqbit modulation setA(t)=
；
Based on long spherical wave function generationNA transmission waveform for radar communication integrationξ 1 (c,t)、ξ 2 (c,t)、…、ξ N (c,t)；
The above-mentionedpAndq、Nsatisfy the relation:
symbol of
Represents rounding down;
step four: according to a one-to-one mapping relation, the method comprises the following steps ofpEach of the bit mapping groupsA data combination is mapped to be respectively from theNA transmission waveform for integrating radar communication is selected fromqA waveform combination consisting of a plurality of transmission waveforms; the above-mentionedpEach data combination in the bit mapping group can only correspond to one waveform combination, and the waveform combinations corresponding to any two data combinations are different;
step five: using waveform amplitude modulation, modulating saidqEach bit of the bit modulation group is loaded to the bit modulation groupqOn the transmission waveform, a time domain waveform is formed by overlapping the time domain waveform and then the carrier signal
And multiplying to form a modulation signal for radar communication integration.
Further, in the technical solution disclosed in the present invention, the carrier signal
Frequency of (2)f c And pseudo-randomly selecting the preset frequency points in the working frequency band of radar communication integration, and changing according to a frequency hopping mode.
Another object of the present invention is to enable a data transmission rate to be adapted to a channel environment to improve adaptability of a modulated signal to the channel environment.
In order to achieve the purpose of the invention, the invention provides a rate adaptive modulation method for radar communication integration. In the technical scheme disclosed by the invention, the slaveNSelection from transmission waveforms for radar communication integrationqA transmit waveform to form a waveform combination, saidqIs detected as a function of the channel interferenceσDynamically adjusted by changes in;
if the channel interference detection value is in the current statistical periodσWhen the value of the previous statistical period is increased, the value of the previous statistical period is increasedqIs decreased by 1, ifqIf the value of (1) is 1 before the adjustment, the adjustment is not performed; if the channel interference detection value is in the current statistical periodσCompared with the value of the previous statistical periodWhen reduced, saidqIs added by 1, ifqBefore the value adjustment is changed isN-1, no more adjustment; the above-mentionedqIs initially of
Symbol of
Indicating a rounding down.
Further, in the technical solution disclosed in the present invention, the channel interference detection value isσThe statistical method comprises the following steps:
wherein the content of the first and second substances,Mthe number of frequency hopping points is represented,Bindicating the modulated signal bandwidth for radar communication integration,T s which represents the size of the statistical period,f i indicating the frequency of the frequency hopping bins,
、
respectively expressed in the statistical periodT s Internal frequency hopping frequency pointf i The number of impulse interferers and the number of continuous interferers received,
、
respectively expressed in the statistical periodT s Internal frequency hopping frequency pointf i The spectral bandwidth of the impulse interference and the spectral bandwidth of the continuous interference received,
、
respectively expressed in the statistical periodT s Internal frequency hopping frequency pointf i The time period of the above received impulse interference and the time period of the continuous interference.
Further, in the technical solution disclosed in the present invention, the data to be transmitted by the user is describedD(t) RS encoded to form encoded dataK(t) The RS is encoded as RS (30 +)r30), whereinrA supervisory bit number inserted for RS encoding, saidrIs detected as a function of the channel interferenceσDynamically adjusted by changes in;
if the channel interference detection value is in the current statistical periodσWhen the value of the previous statistical period is increased, the value of the previous statistical period is increasedrIs added by 1, ifrIf the value of (1) is 30 before the adjustment change, the adjustment is not carried out; if the channel interference detection value is in the current statistical periodσSaid value decreases compared to the value of the previous statistical periodrIs decreased by 1, ifrIf the value of (1) is 10 before the adjustment change, the adjustment is not carried out; the above-mentionedrIs initially ofr=20。
Preferably, in the technical solution disclosed in the present invention, the modulation signal for radar communication integration is transmitted in the form of a pulse, a cycle of the pulse includes a pulse transmission period and a pulse stop period, the time length of the pulse transmission period is 6.6 microseconds, and the time length of the pulse stop period is 6.6 microseconds.
Preferably, in the technical solution disclosed in the present invention, the transmission waveform for radar communication integration is a transmission waveform designed based on a prolate spheroid wave function, and 0 order, 2 order, 4 order and 6 order prolate spheroid wave functions are respectively selected in the order of frequency domain energy aggregation from large to small.
Preferably, in the technical solution disclosed in the present invention, the interleaving method is convolutional interleaving.
Compared with the prior art, the invention has the following beneficial effects:
(1) The information transmission rate is improved.
In the technical scheme disclosed by the invention, the traditional mode of loading information only by adopting amplitude parameters is abandoned, the way of transmitting waveform loading information is expanded, and information is loaded simultaneously by adopting two modes of waveform mapping and waveform amplitude modulation; furthermore, the transmission waveform for loading the information only uses a half of the frequency spectrum based on the symmetrical characteristic of the frequency spectrum, so that the utilization rate of the frequency spectrum is effectively improved, and the information transmission rate of the system is improved.
(2) Has rate adaptation capability.
In the technical scheme disclosed by the invention, the channel quality is measured by counting the channel interference detection value, and the number of transmission waveforms participating in amplitude modulation and the coding mode (code rate) of RS (Reed-Solomon) coding are adjusted according to the channel interference detection value, so that the transmission rate can be adapted to the channel interference condition, and the self-adaptive capacity of the system is improved.
(3) The anti-interference capability of the modulation signal is improved.
In the technical scheme disclosed by the invention, the transmission waveform is designed based on the long spherical wave function, compared with the sine and cosine function adopted by OFDM in the prior art, the designed transmission waveform has smaller side lobe amplitude, and generates smaller signal distortion when being filtered by an antenna, thereby improving the anti-interference capability of the modulation signal in the channel transmission process. Furthermore, the number of the supervision bits inserted in the RS codes can be automatically adjusted according to the channel interference condition, when the channel interference is severe, the number of the supervision bits is increased, the error detection and correction capability is enhanced, the RS codes can adapt to the channel environment, and the reliability of information transmission is improved.
Additional advantages and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
Fig. 1 is a schematic diagram of spectrum truncation according to an embodiment of the present invention, where (a) is an odd symmetric spectrum, (b) is a half-truncated spectrum, (c) is an even symmetric spectrum, and (d) is a half-truncated spectrum.
Fig. 2 is a schematic diagram of modulation signal generation according to an embodiment of the present invention.
Detailed Description
The principles and features of the present invention will be described with reference to fig. 1-2, which are provided for illustration only and are not intended to limit the scope of the invention.
In the prior art, the OFDM has the characteristic of high spectrum utilization rate, so that the OFDM is widely applied to the field of radar communication integration. The essence of the OFDM technology is that information is modulated by a plurality of subcarriers which are orthogonal pairwise and have 50 percent of overlapped frequency spectrums, and amplitude parameters are adopted to carry the information. The existing modulation method generally realizes information loading through one or a combination of three parameters of amplitude, frequency or phase of sine and cosine carrier waves, and the method has a dominant position, however, the method also limits the exploration space for improving the spectrum efficiency in the communication field to a certain extent. Furthermore, the OFDM technology adopts sine and cosine functions with a plurality of frequency spectrums overlapped by 50% to carry information, and the sine and cosine functions have large side lobes, so that the energy of the side lobes of the modulated signals is large, and the filtered side lobes can cause the modulated signals to generate serious distortion when the modulated signals are sent to an antenna for filtering, thereby reducing the anti-interference capacity of the modulated signals in channel transmission.
Long spherical Wave Functions (PSWFs) in a given time interval [ -T s /2，T s /2]In the following, the following integral equation is satisfied:
wherein the content of the first and second substances,
is composed ofnThe characteristic value corresponding to the order spherical wave function is used for representing the energy concentration factor,nin order of the steps,
is angular frequency，cIs a time bandwidth product factor. The radar antenna has the characteristic of optimal energy gathering performance, so that the radar antenna has wide application in the field of radar communication. Under the condition of a certain time bandwidth product factor, a plurality of orders of long spherical wave functions which are orthogonal pairwise and have mutually overlapped frequency spectrums can also exist at the same time, and the frequency spectrum overlapping is more than 50 percent. The inventor designs a transmission waveform by taking the orthogonality and the frequency spectrum overlapping of the function as starting points, and adopts a plurality of long spherical wave functions with mutually overlapped frequency spectrums as information carriers to modulate information so as to achieve the purpose of improving the frequency spectrum utilization rate. The orthogonality can be used for separation at a receiving end, so that the intersymbol interference is eliminated, and the information is demodulated. Compared with sine and cosine functions adopted by OFDM modulation, the long spherical wave function has more advantages in the aspect of energy aggregation, the side lobe of the signal is small, the generated waveform distortion is small when antenna filtering is carried out, and the long spherical wave function has strong anti-jamming capability when used for channel transmission. Therefore, compared with the sine and cosine function, the transmission waveform is designed based on the prolate spherical wave function, and better performance is brought.
The inventor can find out by analyzing the spectrum characteristics of the long spherical wave function that the spectrum of the even-order or odd-order long spherical wave function has the following characteristics:
therefore, the odd-order long spherical wave function has the frequency spectrum odd symmetry characteristic in the frequency domain, and the even-order long spherical wave function has the frequency spectrum even symmetry characteristic in the frequency domain. Based on the characteristics, when a transmission waveform is designed by adopting an odd-order or even-order long spherical wave function, the transmission waveform can be designed by utilizing the symmetrical characteristic of the frequency spectrum, the frequency spectrum is intercepted, a half of the frequency spectrum is intercepted, the conversion relation from the frequency domain to the time domain is utilized, the time domain waveform is converted, and then information loading is carried out, so that the frequency spectrum utilization rate can be greatly improved, and the information transmission rate is improved. The method comprises the steps of carrying out frequency domain transformation on odd-order or even-order long spherical wave functions, intercepting a half frequency spectrum according to the symmetrical characteristic of the frequency spectrum, and respectively converting the frequency spectrum into time domain waveforms according to the transformation relation from the frequency domain to the time domain to form transmission waveforms for loading data. As shown in (a) and (c) of fig. 1, the spectrums of the prolate spherical wave function with odd symmetry characteristic and even symmetry characteristic are respectively, and the spectrums after being cut by half are shown in (b) and (d) of fig. 1 according to the spectrum symmetry characteristic. When the receiving end demodulates the information, firstly, according to the time period length of the data code element, the received signal is subjected to spectrum symmetry copying according to the spectrum symmetry, the whole spectrum of the transmission waveform is recovered, then, the time domain orthogonality is utilized to carry out signal separation, and the information extraction is completed.
Therefore, in the technical scheme disclosed by the embodiment of the invention, the transmission waveform is designed based on the prolate spheroidal wave function, only the spectrum signal within a half spectrum range is transmitted, the spectrum is copied at the receiving end according to the spectrum symmetry, the full spectrum signal is recovered, and the information is demodulated, so that the spectrum utilization efficiency is greatly improved. Moreover, at the receiving end, the spectrum is copied according to the spectrum symmetry, so that the symmetric distortion of the modulation signal caused by interference in the transmission process can be further corrected, and the anti-interference capability of signal transmission can be improved. Therefore, according to the technical scheme disclosed by the embodiment of the invention, the transmission waveform of the loading information is designed by adopting the half-spectrum prolate spheroidal wave function, so that the improvement of the spectrum utilization rate of the system is facilitated.
In the prior art, when a long spherical wave function is used for information transmission in the communication field, information is only loaded through an amplitude parameter, and although the long spherical wave function has certain advantages compared with an OFDM modulation mode, the improved space is greatly restricted by the information loading mode.
In order to further improve the frequency band utilization rate of the system, the inventor abandons the traditional mode of only adopting amplitude parameters to load information and expands the way of transmitting waveform loading information. And information is loaded simultaneously by adopting two modes of waveform mapping and amplitude modulation so as to further improve the spectral efficiency of the system.
Further, in the present invention,in the technical solution disclosed in the embodiment of the present invention, the waveform mapping is to select a part of transmission waveforms from a plurality of transmission waveforms to form a waveform combination, and the selected waveform combination is unknown and has a certain probability, so that information can be carried. For example, 3 kinds of transmission waveforms are selected from 4 kinds of transmission waveforms to constitute a waveform combination, and the probability of occurrence of any one group of waveform combinations consisting of 3 kinds of transmission waveforms is one fourth, and as can be seen from the information theory, two bits of information can be carried, that is, information of two bits can be carried
bit; then each waveform in the selected 3 waveforms adopts amplitude parameter loading information, namely the forward amplitude and the reverse amplitude of the transmission waveform are utilized to represent two states of 1-bit binary digital information, so that the amplitude parameter of each waveform can load 1-bit information, and 3 waveforms can load 3-bit information. Therefore, 2bit +3bit =5bit information can be loaded in the two modes of waveform mapping and amplitude parameter; however, if the traditional method of loading information by using a single amplitude parameter is adopted, only 4 bits of information can be loaded by 4 transmission waveforms. Therefore, compared with the prior art, the method and the device adopt two modes of waveform mapping and amplitude parameter loading to load information, and can effectively improve the information transmission capability. When loading information, the information to be transmitted by the user is processed according to the following formulap+q) The bit size is grouped, the grouping comprisingpBit map set sumqA bit modulation group, saidpThe data combination of the bit mapping group is mapped into a waveform combination according to a one-to-one mapping relation by adopting a waveform mapping mode, so that information loading is realized; the above-mentionedqAnd the data in the bit modulation group is loaded by adopting waveform amplitude modulation. At a receiving end, a received signal is extracted according to the mapping relation between the waveform combination and the data combinationpMapping the data of the group, and then demodulating the data according to the corresponding relation between the amplitude of the waveform amplitude modulation signal and the informationqThe bits modulate the block data. Therefore, the technical scheme disclosed by the embodiment of the invention adopts the waveform mapping and the amplitude parameter to carry information at the same time, and improves the information transmission capability compared with the traditional mode of loading information by using a single amplitude parameter.
Further, in the technical solution disclosed in the embodiment of the present invention, in order to improve reliability of information transmission, data to be transmitted by a user is first subjected to RS coding, so as to improve the random interference resistance of a modulation signal; further, in order to combat the burst interference, the RS-encoded signal is interleaved by an interleaving method to generate an interleaved signal, so as to enhance the capability of combating the burst interference, and the burst interference is scattered and converted into random interference, thereby enhancing the reliability of information transmission.
Furthermore, in the technical solution disclosed in the embodiment of the present invention, in the second embodimentkThe radar communication integrated modulation signal in each data code element period is as follows:
wherein the content of the first and second substances,f c is the carrier frequency and is,a j (t) Is as followsjThe bits are used for waveform amplitude modulated data to be transmitted,qis a positive integer and represents the number of radar communication integrated transmission waveforms participating in waveform amplitude modulation,ξ j (c,t) Is as followsjA transmission waveform for waveform amplitude modulation,cis a time-bandwidth product factor;
the design method of the radar communication integrated transmission waveform comprises the following steps: according to the sequence of the energy accumulation of the frequency domain from big to smallNEven order or odd order long spherical wave function; respectively intercepting the long spherical surface wave function according to the frequency spectrum symmetry of the long spherical surface wave functionNHalf frequency spectrums of even-order or odd-order long spherical wave functions are converted into time-domain waveforms according to the conversion relation from the frequency domain to the time domainξ j (c,t)，j=1，2，…，NForm aNA transmission waveform, saidqAndNthe relationship of (c) is:qis greater than or equal to 1 and less thanNIs a positive integer of (1).
Further, in the technical solution disclosed in the embodiment of the present invention, as shown in fig. 2, generating the modulation signal includes the following steps:
the method comprises the following steps: data to be transmitted by a userD(t) After RS encoding, form the encoded dataK(t)；
Step two: the coded dataK(t) Interleaving by an interleaving method to generate an interleaved signalZ(t)；
Step three: interleaving the signalZ(t) Performing a grouping, the grouping comprisingpBit map setY(t)=
Andqbit modulation setA(t)=
；
Based on long spherical wave function generationNA transmission waveform for radar communication integrationξ 1 (c,t)、ξ 2 (c,t)、…、ξ N (c,t)；
The above-mentionedpAndq、Nsatisfy the relation:
symbol of
Represents rounding down;
step four: according to a one-to-one mapping relation, the method comprises the following steps ofpEach data combination of the bitmap group is mapped to be respectively mapped from the bit map groupNA transmission waveform for integrating radar communication is selected fromqA waveform combination consisting of a plurality of transmission waveforms; the above-mentionedpEach data combination in the bit mapping group can only correspond to one waveform combination, and the waveform combinations corresponding to any two data combinations are different;
step five: using waveform amplitude modulation, modulating saidqEach bit of the bit modulation group is loaded to the bit modulation groupqOn a transmission waveform, then a time domain waveform is superposed to form a time slotThe domain waveform, and then the carrier signal
And multiplying to form a modulation signal for radar communication integration.
Preferably, the interleaving method is convolutional interleaving. Regarding the implementation of convolutional interleaving, it is obvious to those skilled in the art that the interleaving method can be implemented based on the prior knowledge and conventional means, and will not be described here.
Further, in the technical solution disclosed in the embodiment of the present invention, the carrier signal is
Frequency of (2)f c Pseudo-random selection is carried out in preset frequency points in a working frequency band of radar communication integration, namely a plurality of frequency points are preset in the working frequency band, and when signals are transmitted, the carrier signals are transmitted
Frequency of (2)f c And pseudo-randomly selecting from the preset frequency points, and changing according to a frequency hopping mode to resist tracking interference. It will be apparent to those skilled in the art that the frequency hopping can be implemented based on prior knowledge and conventional means, and will not be described in detail herein.
Preferably, in the technical solution disclosed in the embodiment of the present invention, the first 4 even-order prolate spheroidal wave functions are taken in the order of the frequency domain energy aggregation from large to small
、
、
And
designing a transmission waveform, intercepting a frequency spectrum in a half frequency spectrum range according to even-order long spherical wave function frequency spectrum even symmetry characteristics in a frequency domain, and respectively converting the frequency spectrum into a time domain waveform according to a conversion relation from the frequency domain to the time domainξ 0 (c,t)、ξ 2 (c,t)、ξ 4 (c,t) Andξ 6 (c,t) 4 transmission waveforms are formed. And after RS coding and interweaving information to be transmitted by a user, grouping the information according to the size of 5 bits, wherein the grouping comprises a 2-bit mapping group and a 3-bit modulation group. And the 2-bit mapping group respectively maps each data combination of the 2-bit mapping group into a waveform combination consisting of 3 transmission waveforms selected from the 4 transmission waveforms according to a one-to-one mapping relationship, and the corresponding relationship between the data combination of the mapping group and the transmission waveform combination is shown in table 1.
TABLE 1 one-to-one correspondence of mapping group data combinations to waveform combinations
In the technical solution disclosed in the embodiment of the present invention, the one-to-one mapping relationship between the data combinations and the waveform combinations in the mapping group is not limited to table 1, as long as it can be satisfied that each data combination in the mapping group has only one waveform combination corresponding to it, and the waveform combinations corresponding to any two data combinations are different from each other.
Preferably, in the embodiments of the present invention,p=2，Nand =4. And after the mapping between the data combination and the waveform combination is finished, each waveform in the mapped waveform combination is subjected to waveform amplitude modulation respectively to finish the second information loading. For example, the waveform combination mapped by data combination 00 described in Table 1 isξ 2 (c,t)、ξ 4 (c,t)、ξ 6 (c,t) Each waveform in the waveform combination is then respectively subjected to waveform amplitude modulation, namely, the forward amplitude and the reverse amplitude of the waveform are respectively used for representing 1-bit binary signalsAnd (4) two states, thereby completing the loading of the 3-bit data in the modulation group. The transmission waveform after information loading is completed, and then a time domain waveform is formed by overlapping the time domain waveform and then is mixed with the carrier signal
The multiplication is performed to form a modulated signal.
It can be known from the above analysis that, in the technical solution disclosed in the embodiment of the present invention, information is loaded simultaneously through two ways of waveform mapping and amplitude modulation, and the designed 4 transmission waveforms can transmit 5bit (2bit + 3bit) information, whereas in the prior art, if only waveform amplitude modulation is adopted, 4 transmission waveforms can only transmit 4bit information. Therefore, the technical scheme disclosed by the embodiment of the invention improves the information transmission rate. Furthermore, in the technical scheme disclosed by the embodiment of the invention, the transmission waveform sent to the channel is only a half frequency spectrum, so that the frequency spectrum resource is saved, and the frequency spectrum utilization rate is improved; and the peak value of the transmission waveform sidelobe is small, the generated waveform distortion is small when the antenna filtering is carried out, and the anti-interference capability is strong when the antenna filtering is used for channel transmission.
In the prior art, the transmission rate of the system is usually not changed, in order to resist human interference and guarantee smooth communication in a complex electromagnetic environment, a channel coding technology with strong error correction capability is usually adopted to perform error detection and correction, and the information transmission rate is reduced due to the insertion of additional supervisory bit data, namely, the method usually trades the effectiveness of the system for reliability. The transmission channel environment is constantly changing, however, in the prior art, the adopted error correction coding mode is not changed, the error detection and correction capability of the system is not changed, and the data transmission rate of the system is also not changed, which is obviously unreasonable.
In order to solve the problems in the prior art, the technical scheme disclosed by the embodiment of the invention discloses a statistical calculation method for a channel interference detection value. The channel interference detection valueσThe statistical calculation method comprises the following steps:
wherein the content of the first and second substances,Mthe number of frequency hopping points is represented,Brepresents the bandwidth of the radar communication integrated modulation signal,T s which represents the size of the statistical period,f i indicating the frequency of the frequency hopping bins,
、
respectively expressed in the statistical periodT s Internal frequency hopping frequency pointf i The number of impulse interferers and the number of continuous interferers received,
、
respectively expressed in the statistical periodT s Internal frequency hopping frequency pointf i The spectral bandwidth of the impulse interference and the spectral bandwidth of the continuous interference received,
、
respectively expressed in the statistical periodT s Internal frequency hopping frequency pointf i The time period of the above received impulse interference and the time period of the continuous interference. In the technical scheme disclosed by the embodiment of the invention, in the statistical periodT s In the method, parameters such as the occurrence frequency of pulse interference and continuous interference, interference bandwidth, interference duration and the like are counted to realize the detection of the current channel environment quality, and the parameters are used as the basis for adjusting the coding mode and the transmission rate.
Further, in the technical solution disclosed in the embodiment of the present invention, the transmission waveforms for loading information are orthogonal in time domain and overlapped in frequency spectrum, and when the channel interference is serious, the orthogonality between the transmission waveforms is affected by the interference signal in the channel, thereby affecting the information demodulation at the receiving end, and causing the error rate to rise. Therefore, when the channel interference is serious, the number of transmission waveforms for loading information should be reduced, and the information transmission rate should be reduced to improve the reliability of information transmission. On the contrary, when the channel environment is better, the number of transmission waveforms for loading information can be increased appropriately to increase the information transmission rate of the system.
Furthermore, in the technical scheme disclosed by the embodiment of the invention, the slave unitNSelection from a transmission waveformqA transmission waveform to form a waveform combination, saidqIs detected as a function of the channel interferenceσDynamically adjusted by changes in;
if the channel interference detection value is in the current statistical periodσWhen the value of the previous statistical period is increased, i.e. the channel interference is deteriorated, the value of the previous statistical period is increasedqIs decreased by 1, the number of transmission waveforms used for loading information is decreased, ifqIf the value of (1) is 1 before the adjustment change, the adjustment is not performed; if the channel interference detection value is in the current statistical periodσThe channel environment is improved when the value is reduced compared with the previous statistical period, the methodqAdding 1 to the value of (b), increasing the number of transmission waveforms used to load the information, ifqBefore the value adjustment is changed isN-1, no more adjustment; the describedqIs initially of
Symbol of
Indicating a rounding down.
For example, the transmission waveform designed based on the prolate spherical wave function isξ 0 (c,t)、ξ 2 (c,t)、ξ 4 (c,t) Andξ 6 (c,t) I.e. N =4.In the previous statistical period, grouping is carried out according to the size of 5 bits, the grouping comprises a 2-bit mapping group and a 3-bit modulation group, the mapping group data combination and the waveform combination have one-to-one correspondence as shown in table 1, and 3 transmission waveforms participate in amplitude modulation, namely 3 transmission waveforms participate in amplitude modulationqAnd =3. When the channel transmission environment changes, the channel interference detection value is detected in the current statistical periodσThe value of the previous statistical period is increased, namely the channel environment interference is serious, the value of the previous statistical period is increasedqIs decreased by 1, i.e.qThe change is adjusted from 3 to 2, and 2 transmission waveforms are selected from 4 transmission waveforms to form a waveform combination. From the abovepAndq、Nsatisfied relational expression
In a clear view of the above, it is known that,pand (2). Namely, in the previous statistical period, grouping is carried out according to the size of 4 bits, and the grouping comprises a 2-bit mapping group and a 2-bit modulation group. And according to a one-to-one mapping relationship, mapping each data combination of the 2-bit mapping group into a waveform combination consisting of 2 transmission waveforms selected from the 4 transmission waveforms, wherein the corresponding relationship between the data combination of the mapping group and the transmission waveform combination is shown in table 2. Then, each waveform in the waveform combination is subjected to waveform amplitude modulation respectively so as to complete the loading of 2-bit data in the modulation group. At this time, the information carrying capacity of the transmission waveform is changed from 5 bits to 4 bits in the last statistical period, so that the information transmission rate is changed, the number of the waveforms participating in amplitude modulation is also adjusted from 3 transmission waveforms to 2 transmission waveforms, the mutual influence among the transmission waveforms is also reduced, and the capacity of resisting channel interference is stronger.
Table 2 one-to-one correspondence relationship between mapping group data combinations and waveform combinations after channel environment changes
In the prior art, in order to combat human interference and ensure smooth transmission of a modulation signal in a complex electromagnetic environment, a channel coding technology with strong error correction capability is generally adopted to perform error detection and correction. The information transmission rate is reduced due to the insertion of additional supervisory bit data by channel coding techniques, i.e., this approach usually trades off system efficiency for reliability. However, the transmission channel environment is constantly changing, the error correction coding method adopted in the prior art is fixed, the error detection and correction capability is also fixed, the same error correction coding method is adopted no matter the channel environment is good, the same number of supervision bits are inserted, and the same information transmission rate is sacrificed, which is obviously unreasonable.
In order to solve the problems in the prior art, in the technical scheme disclosed by the embodiment of the invention, the data to be transmitted by the user is transmittedD(t) RS encoded to form encoded dataK(t) The RS is encoded as RS (30 +)r30) a coding scheme whereinrA parity number inserted for RS encoding to implement error detection and correction, the coderIs detected as a function of the channel interferenceσDynamically adjusted by changes in;
if the channel interference detection value is in the current statistical periodσWhen the value of the previous statistical period is increased, the value of the previous statistical period is increasedrAdding 1 to the value of (A), increasing the number of supervisory bits to enhance error detection and correction capability and reduce information transmission rate, if so, adding 1 to the value of (A), otherwise, adding more supervisory bits to enhance error detection and correction capabilityrIf the value of (1) is 30 before the adjustment change, the adjustment is not carried out; if the channel interference detection value is in the current statistical periodσWhen the value of the previous statistical period is reduced, the value of the previous statistical period is reducedrThe numerical value of (1) is reduced, the number of supervision bits is reduced, the error detection and correction capability is reduced, and the information transmission capability is increased if the numerical value is less than 1rIf the value of (1) is 10 before the adjustment change, the adjustment is not carried out; the above-mentionedrIs at an initial value ofr=20. For those skilled in the art, the implementation method of coding and decoding of RS can be implemented based on the prior art and conventional methods, and will not be described herein again.
Further, in the technical solution disclosed in the embodiment of the present invention, the modulation signal is transmitted in a pulse form. The pulse form is transmitted, so that the frequency spectrum bandwidth of a modulation signal can be further expanded, the power spectrum density of the signal is reduced, and the concealment capability of the signal is improved; further, the modulation signal for radar communication integration is transmitted in a pulse form, the pulse period comprises a pulse transmitting period and a pulse stop period, the time length of the pulse transmitting period is 6.6 microseconds, and the time length of the pulse stop period is 6.6 microseconds, so that the anti-forwarding interference capability of the modulation signal is further enhanced.
While embodiments of the invention have been disclosed above, it is not intended to be limited to the uses set forth in the specification and examples. It can be applied to all kinds of fields suitable for the present invention. Additional modifications will readily occur to those skilled in the art. It is therefore intended that the invention not be limited to the exact details and illustrations described and illustrated herein, but fall within the scope of the appended claims and equivalents thereof.
Claims (8)
1. A rate adaptive modulation method for radar communication integration is characterized in that,
generating the modulated signal comprises the steps of:
the method comprises the following steps: data to be transmitted by a userD(t) RS encoded to form encoded dataK(t) The RS is encoded as RS (30 +)r30), whereinrA supervisory bit number inserted for RS encoding, saidrIs detected as a function of the channel interferenceσDynamically adjusted by changes in;
step two: the coded dataK(t) Interleaving by an interleaving method to generate an interleaved signalZ(t)；
Step three: interleaving the signalZ(t) Performing a grouping, the grouping comprisingpBit map setY(t)= 
Andqbit modulation setA(t)= 
；
Based on long spherical wave function generationNA transmission waveform for radar communication integrationξ 1 (c,t)、ξ 2 (c,t)、…、ξ N (c,t)；
The above-mentionedpAndq、Nsatisfy the relation:
symbol of
Represents rounding down;
step four: according to a one-to-one mapping relation, the method comprises the following steps ofpEach data combination of the bitmap group is respectively the slaveNA transmission waveform for integrating radar communication is selected fromqA waveform combination consisting of a plurality of transmission waveforms; the above-mentionedpEach data combination in the bit mapping group can only correspond to one waveform combination, and the waveform combinations corresponding to any two data combinations are different;
step five: using waveform amplitude modulation, modulating saidqEach bit of the bit modulation group is loaded to the bit modulation groupqOn a transmission waveform, a time domain waveform is formed by overlapping the time domain waveform and then the time domain waveform and a carrier signal
Multiplying to form a modulation signal for radar communication integration;
in the first placekThe radar communication integrated modulation signal in each data code element period is as follows:
wherein the content of the first and second substances,f c is the carrier frequency and is,a j (t) Is as followsjThe bits are used for waveform amplitude modulated data to be transmitted,qis a positive integer and represents the number of radar communication integrated transmission waveforms participating in waveform amplitude modulation, theqIs a value ofDetecting value of interference with channelσIs dynamically adjusted by the change of the pressure sensor,ξ j (c,t) Is as followsjA transmission waveform for waveform amplitude modulation,cis a time-bandwidth product factor;
the design method of the radar communication integrated transmission waveform comprises the following steps: according to the sequence of the energy accumulation of the frequency domain from big to smallNEven order or odd order long spherical wave function; respectively intercepting the long spherical surface wave function according to the frequency spectrum symmetry of the long spherical surface wave functionNHalf frequency spectrums of even-order or odd-order long spherical wave functions are converted into time-domain waveforms according to the conversion relation from the frequency domain to the time domainξ j (c,t)，j=1，2，…，NForm aNA transmission waveform for integration of radar communication, saidqAndNthe relationship of (1) is:qis greater than or equal to 1 and less thanNIs a positive integer of (1).
2. The adaptive rate modulation method for radar communication integration according to claim 1, wherein the carrier signal is
Frequency of (2)f c And pseudo-randomly selecting the preset frequency points in the working frequency band of radar communication integration, and changing according to a frequency hopping mode.
3. The method of claim 2, wherein the rate adaptive modulation is derived from the modulation of the radar communication integrationNSelection from transmission waveforms for radar communication integrationqA plurality of transmit waveforms to form a waveform combination;
if the channel interference detection value is in the current statistical periodσWhen the value of the previous statistical period is increased, the value of the previous statistical period is increasedqIs decreased by 1, ifqIf the value of (1) is 1 before the adjustment change, the adjustment is not performed; if the channel interference detection value is in the current statistical periodσWhen the value of the previous statistical period is reduced, the value of the previous statistical period is reducedqIs added by 1, ifqNumber ofBefore the value is adjusted and changed areN-1, no more adjustment; the above-mentionedqIs initially of
Symbol of
Indicating a rounding down.
4. The adaptive rate modulation method according to claim 3, wherein the channel interference detection value is detected by a rate adaptive modulation methodσThe statistical method comprises the following steps:
wherein the content of the first and second substances,Mthe number of frequency hopping points is represented,Bindicating the modulated signal bandwidth for radar communication integration,T s which represents the size of the statistical period,f i indicating the frequency of the frequency hopping bins,
、
respectively expressed in the statistical periodT s Internal frequency hopping frequency pointf i The number of impulse interferers and the number of continuous interferers received,
、
respectively expressed in the statistical periodT s Internal frequency hopping frequency pointf i The spectral bandwidth of the impulse interference and the spectral bandwidth of the continuous interference received,
、
respectively expressed in the statistical periodT s Internal frequency hopping frequency pointf i The time period of the above received impulse interference and the time period of the continuous interference.
5. The adaptive rate modulation method as claimed in claim 4, wherein the channel interference detection value is detected if the channel interference detection value is within the current statistic periodσWhen the value of the previous statistical period is increased, the value of the previous statistical period is increasedrIs added by 1, ifrIf the value of (1) is 30 before the adjustment change, the adjustment is not carried out; if the channel interference detection value is in the current statistical periodσWhen the value of the previous statistical period is reduced, the value of the previous statistical period is reducedrIs decreased by 1, ifrIf the value of (1) is 10 before the adjustment change, the adjustment is not carried out; the above-mentionedrIs initially ofr=20。
6. The method according to claim 5, wherein the modulation signal for radar communication integration is transmitted in the form of a pulse, a period of the pulse includes a pulse transmission period and a pulse stop period, the pulse transmission period is 6.6 microseconds in length, and the pulse stop period is 6.6 microseconds in length.
7. The adaptive rate modulation method according to claim 5, wherein the transmission waveform for radar communication integration is a transmission waveform designed based on a prolate spheroidal wave function with 0 th order, 2 nd order, 4 th order and 6 th order in descending order of frequency domain energy aggregation.
8. The rate adaptive modulation method for radar communication integration according to claim 5, wherein the interleaving method is convolutional interleaving.
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