CN107819709A - A kind of method and device of Moving target detection - Google Patents
A kind of method and device of Moving target detection Download PDFInfo
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- CN107819709A CN107819709A CN201711024002.4A CN201711024002A CN107819709A CN 107819709 A CN107819709 A CN 107819709A CN 201711024002 A CN201711024002 A CN 201711024002A CN 107819709 A CN107819709 A CN 107819709A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/0222—Estimation of channel variability, e.g. coherence bandwidth, coherence time, fading frequency
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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
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/04—Systems determining presence of a target
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/0224—Channel estimation using sounding signals
- H04L25/0228—Channel estimation using sounding signals with direct estimation from sounding signals
- H04L25/023—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols
- H04L25/0232—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols by interpolation between sounding signals
Abstract
The embodiments of the invention provide a kind of method and apparatus of Moving target detection, for improving the accuracy of detection of mobile target, reduce the hardware and software cost of detection.Methods described includes：Receive the data signal of radio-frequency module transmitting, the data signal is converted into time-domain digital baseband signal, wherein, the data signal is to carry out OTFS modulation to pre-set delay Doppler domain symbol, again by one-dimensional inverse fourier transform after, the signal after digital-to-analogue conversion by the radio-frequency module to indoor transmitting；OTFS signal demodulation is carried out to the time-domain digital baseband signal, obtains the channel estimation of delay Doppler domain；Based on the channel estimation, it is determined that the quantity of mobile target.
Description
Technical field
The present invention relates to technical field of steel rolling, more particularly to a kind of method and device of Moving target detection.
Background technology
In the prior art, the non-contact detection of indoor multiple mobile objects, generally use are realized by wireless signal
Receiver based on OFDM (Orthogonal Frequency Division Multiplexing, OFDM) technology
RSSI (Reference Signal Strength Indicator, the reference signal strength) changes of transmission signal are detected, and then
Mobile target is determined whether there is, deviation is very big within a period of time due to RSSI values, is mainly moved by target, channel declines
Fall, the influence of multiple factors such as block, reference signal strength RSSI randomized jitter, nothing can not also be eliminated using the method for difference
Method accurately detects whether multiple mobile targets be present, so, higher false drop rate be present in this detection mode.
Mobile target can also be detected by Active Radar imaging technique in the prior art, emitter is actively launched
The signal of radar, receiver carry out multi-movement target number by receiving the radar return that mobile object and stationary object reflect
Detection, because the operating carriers of conventional radar signal are generally operational in more than ten GHz or even tens GHz, through-wall performance is poor.Pass through
The mode of increase power or the multiple transmitting reception antennas of assembling can realize preferable through-wall performance, but can not realize radio frequency mould
The target of miniaturization and the low-power consumption of block.Also, radar signal needs stronger digital signal processor or FPGA processing, soft
Hardware implementation cost is high.
So the presence of Moving target detection mode can not have accuracy of detection height and software and hardware cost of implementation concurrently in the prior art
Low technical problem.
The content of the invention
The embodiments of the invention provide a kind of method and device of Moving target detection, for improving the detection of mobile target
Precision, reduce the hardware and software cost of detection.
In a first aspect, the invention provides a kind of method of Moving target detection, methods described includes：
The data signal of radio-frequency module transmitting is received, the data signal is converted into time-domain digital baseband signal, wherein,
The data signal be to pre-set delay Doppler domain symbol carry out OTFS (Orthogonal Time Frequency Space,
Orthogonal space) modulation, then by one-dimensional inverse fourier transform after, by the radio-frequency module to room after digital-to-analogue conversion
The signal of interior transmitting；
OTFS signal demodulation is carried out to the time-domain digital baseband signal, obtains the channel estimation of delay Doppler domain；
Based on the channel estimation, it is determined that the quantity of mobile target.
Optionally, it is described that the data signal is converted into time-domain digital baseband signal, including：
After carrying out down-converted and analog-to-digital conversion to the data signal, time-domain digital baseband signal is obtained.
Optionally, the data signal is described that the time-domain digital baseband signal is carried out also added with default frame head
OTFS signals demodulate, and specifically include：
Preamble detecting is carried out to the time-domain digital baseband signal by matched filter；
When detecting frame head, the time-domain digital baseband signal is alignd；
The time-domain digital baseband signal of alignment is subjected to OTFS signal demodulation.
Optionally, it is described to be based on the channel estimation, it is determined that the quantity of mobile target, including：
Related operation is carried out to the channel estimation, obtains correlation matrix；
Eigenvalues Decomposition is carried out to the correlation matrix, obtains at least one characteristic value；
Based at least one characteristic value, it is determined that the quantity of mobile target.
Optionally, it is described to be based on the characteristic value, it is determined that the quantity of mobile target, including：
Obtain the quantity for the characteristic value for being more than predetermined threshold value at least one characteristic value；
Determine the quantity that the quantity for being more than the characteristic value of predetermined threshold value at least one characteristic value is mobile target.
Optionally, the pre-set delay Doppler domain symbol is correspondingly arranged on pre-set delay Doppler domain pilot tone, described pre-
If postpone number of the Doppler domain pilot tone based on Doppler's positive number frequency deviation | v | and the number of channel latency | l | set, it is described default
Postpone in delay Doppler domain corresponding to Doppler domain symbol, real number A and-A be interleaved alternately with delay Doppler domain position x (v,
L) place, wherein, x (0,0)=A, x (v, 1)=- x (v-1,1), x (1, l)=- x (1, l-1), remaining position is defined as 0.
Second aspect, the embodiment of the present invention provide a kind of Moving target detection device, and described device includes：
Radio-frequency module, for receiving the data signal of the radio-frequency module transmitting, the data signal is converted into time domain
Digital baseband signal, wherein, the data signal is that the radio-frequency module carries out OTFS tune to pre-set delay Doppler domain symbol
System, then by one-dimensional inverse fourier transform after, to the signal of indoor transmitting after digital-to-analogue conversion；
Channel estimation module, for carrying out OTFS signal demodulation to the time-domain digital baseband signal, how general obtain delay
Strangle the channel estimation in domain；
Determining module, for based on the channel estimation, it is determined that the quantity of mobile target.
Optionally, the radio-frequency module is specifically used for when the data signal is converted into time-domain digital baseband signal：
After carrying out down-converted and analog-to-digital conversion to the data signal, time-domain digital baseband signal is obtained.
Optionally, the data signal is also added with default frame head, and the channel estimation module is to the time-domain digital base
Band signal be specifically used for during the demodulation of OTFS signals：
Preamble detecting is carried out to the time-domain digital baseband signal by matched filter；
When detecting frame head, the time-domain digital baseband signal is alignd；
The time-domain digital baseband signal of alignment is subjected to OTFS signal demodulation.
Optionally, the determining module is based on the channel estimation, it is determined that being specifically used for during the quantity of mobile target：
Related operation is carried out to the channel estimation, obtains correlation matrix；
Eigenvalues Decomposition is carried out to the correlation matrix, obtains at least one characteristic value；
Based at least one characteristic value, it is determined that the quantity of mobile target；
Wherein, it is described to be based on the characteristic value, it is determined that the quantity of mobile target, including：
Obtain the quantity for the characteristic value for being more than predetermined threshold value at least one characteristic value；
Determine the quantity that the quantity for being more than the characteristic value of predetermined threshold value at least one characteristic value is mobile target.
Optionally, the pre-set delay Doppler domain symbol is correspondingly arranged on pre-set delay Doppler domain pilot tone, described pre-
If postpone number of the Doppler domain pilot tone based on Doppler's positive number frequency deviation | v | and the number of channel latency is set, described preset is prolonged
In delay Doppler domain corresponding to slow Doppler domain symbol, real number A and-A are interleaved alternately with delay Doppler domain position x (v, l)
Place, wherein, x (0,0)=A, x (v, 1)=- x (v-1,1), x (1, l)=- x (1, l-1), remaining position is defined as 0.
Said one or multiple technical schemes in the embodiment of the present application, at least there is following one or more technology effects
Fruit：
In the technical scheme of the embodiment of the present invention, radio-frequency module modulates pre-set delay Doppler domain symbol through OTFS,
Transmitting to the interior space, is reflected in the signal of transmitting through mobile target after one-dimensional inverse fourier transform and digital-to-analogue conversion again
Afterwards, radio-frequency module receives corresponding data signal, then passes through OTFS after converting digital signals into time-domain digital baseband signal
Signal is demodulated, channel estimation corresponding to acquisition, then the channel estimation of acquisition is analyzed, you can determines mobile target in space
Quantity.Scheme in the application, require relatively low for radio-frequency module, the transmission of signal only can be achieved by single antenna with connecing
To receive, the digital signal structure that radio-frequency module is sent is simple, while has permanent envelope trait, can simplify the design of radio circuit,
Reduce the design requirement of radio circuit.And it is possible to being operated in the free frequency ranges of 2.4GHz and 5.8GHz has well through walls
Performance, it can be ensured that higher accuracy of detection.So the accuracy of detection of mobile target can be effectively improved, the soft of detection is reduced
Hardware cost.
Brief description of the drawings
Fig. 1 is the flow chart for the Detection of Moving Objects that the application first embodiment provides；
Fig. 2 is that the OTFS that the application first embodiment provides modulates schematic diagram；
Fig. 3 is the frame format schematic diagram that the application first embodiment provides；
Fig. 4 is the complete example schematic diagram for the Detection of Moving Objects that the application first embodiment provides；
Fig. 5 is the structural representation for the Moving target detection device that the application second embodiment provides.
Embodiment
The embodiments of the invention provide a kind of method of Moving target detection, for improving the accuracy of detection of mobile target,
Reduce the hardware and software cost of detection.Methods described includes：The data signal of radio-frequency module transmitting is received, the data signal is turned
Time-domain digital baseband signal is changed to, wherein, the data signal is that OTFS modulation is carried out to pre-set delay Doppler domain symbol, then
After one-dimensional inverse fourier transform, the signal after digital-to-analogue conversion by the radio-frequency module to indoor transmitting；To described
Time-domain digital baseband signal carries out OTFS signal demodulation, obtains the channel estimation of delay Doppler domain；Based on the channel estimation,
It is determined that the quantity of mobile target.
Technical solution of the present invention is described in detail below by accompanying drawing and specific embodiment, it should be understood that the application
Specific features in embodiment and embodiment are the detailed description to technical scheme, rather than to present techniques
The restriction of scheme, in the case where not conflicting, the technical characteristic in the embodiment of the present application and embodiment can be mutually combined.
The terms "and/or", only a kind of incidence relation for describing affiliated partner, expression may have three kinds of passes
System, for example, A and/or B, can be represented：Individualism A, while A and B be present, these three situations of individualism B.In addition, herein
Middle character "/", it is a kind of relation of "or" to typically represent forward-backward correlation object.
Fig. 1, the method for Moving target detection provided by the invention are refer to, methods described comprises the following steps：
S101：The data signal of radio-frequency module transmitting is received, the data signal is converted into time-domain digital baseband signal,
Wherein, the data signal is to carry out OTFS modulation to pre-set delay Doppler domain symbol, then passes through one-dimensional inverse fourier transform
Afterwards, the signal after digital-to-analogue conversion by the radio-frequency module to indoor transmitting；
S102：OTFS signal demodulation is carried out to the time-domain digital baseband signal, the channel for obtaining delay Doppler domain is estimated
Meter；
S103：Based on the channel estimation, it is determined that the quantity of mobile target.
Wherein, the pre-set delay Doppler domain symbol is correspondingly arranged on pre-set delay Doppler domain pilot tone, described default
Postpone number of the Doppler domain pilot tone based on Doppler's positive number frequency deviation | v | and the number of channel latency | l | set, described preset is prolonged
In delay Doppler domain corresponding to slow Doppler domain symbol, real number A and-A are interleaved alternately with delay Doppler domain position x (v, l)
Place, wherein, x (0,0) A, x (v, 1)=- x (v-1,1), x (1, l)=- x (1, l-1), remaining position is defined as 0.
After the radio-frequency module carries out down-converted and analog-to-digital conversion to the data signal, time-domain digital baseband is obtained
Signal.
Specifically, in this embodiment, the transmitting antenna and reception antenna of radio-frequency module work simultaneously, radio-frequency module is to default
Time-domain digital baseband signal is converted to by one-dimensional inverse fourier transform after the symbol progress OTFS modulation of delay Doppler domain, then passed through
It is data signal to cross digital-to-analogue conversion, launches the data signal to interior by the transmitting antenna of radio-frequency module, if indoor presence
Mobile target, can reflect the data signal, and then the reception antenna of radio-frequency module receives the data signal of reflection, radio frequency mould
After block carries out down-converted and analog-to-digital conversion to the data signal received again, time-domain digital baseband signal is obtained.
Pre-set delay Doppler domain symbol in the present embodiment is that the symbol for needing to carry out OTFS modulation is mapped into delay
The symbol obtained after Doppler domain, pre-set delay Doppler domain symbol are correspondingly arranged on pre-set delay Doppler domain pilot tone, preset
Postpone number of the Doppler domain pilot tone based on Doppler's positive number frequency deviation | v | and channel latency number | l | set, by real number A and-
A is interleaved alternately with the delay corresponding position x (v, l) of Doppler domain, wherein, x (0,0)=A, x (v, 1)=- x (v-1,1) and x
(1, l)=- x (1, l-1), remaining position are defined as 0.Work as v=5, during l=5, pilot design schematic diagram is as shown in Figure 2.The pilot tone
Static channel (channel of non-moving target) effectively can be influenceed effectively to eliminate by design method, be reformed using simplest two
After inverse fourier transform, you can the channel estimation that the static channel that is eliminated influences.
Further, the present embodiment is modulated using OTFS to pre-set delay Doppler domain symbol, and OTFS modulation is the U.S.
A kind of new type of modulation mode available for 5G communications that cohere companies proposed in 2016.Adjusted with the OFDM used in traditional 4G
Mode processed is different, and OTFS modulation is that the symbol for needing to modulate has been first mapped into delay Doppler domain, rather than traditional OFDM
The frequency domain that modulation system is mapped.The symbol that will be mapped to first on delay Doppler domain is by the pungent Fourier transform mapping of two dimension
Onto whole time-frequency domain.Then by traditional one-dimensional fast fourier inverse transformation, time-domain signal is transformed it into.Finally, will
The time-domain signal is gone out after digital-to-analogue conversion is changed into analog signal by radio-frequency transmissions.Whole process is adjusted with traditional OFDM
The main distinction of system is exactly that with the addition of a new two-dimentional pungent Fourier transform module, complete OTFS modulated process such as Fig. 3
It is shown.
The pungent Fourier transform of two dimension can use equation below (1) to describe：
Wherein, v is expressed as causing integer Doppler shift by time change channel, and l is expressed as l-th of channel latency, N tables
The number of OFDM symbol is shown as, K is expressed as OFDM subcarrier numbers, and n is expressed as the OFDM symbol moment, and k is expressed as k-th
OFDM subcarriers.X (n, k) is expressed as the signal of n-th of moment, k-th of subcarrier, and it is whole that x (v, l) is expressed as the ν Doppler's frequency
The symbol of the need modulation of number l-th of channel latency of frequency deviation.The symbol can be constellation symbol such as BPSK, the QPSK of any modulation,
QAM etc..
One-dimensional inverse fourier transform can use equation below (2) to describe：
Wherein, x (n, t) is expressed as the signal at t-th of moment within n-th of OFDM symbol time.By formula (1) and public affairs
Formula (2), modulation symbol have transformed to time domain from delay Doppler domain.OTFS is demodulated into the inverse process of OTFS modulation, therefore can
After being demodulated by above-mentioned inverse processSignal.
Further, in order to accurately receive data signal, in the present embodiment, radio-frequency module is more by pre-set delay
After general Le domain symbol carries out OTFS modulation, then after being converted to time-domain digital baseband signal by one-dimensional inverse fourier transform, also need
Default frame head is added to the time-domain baseband data signal.The default frame head of addition is mainly used in frame detection, is used in the present embodiment
Frame format as shown in figure 3, can use a variety of sequences Designs preset frame head, can be according to actual need in specific implementation process
Set, here, the application is not limited.
And then the data signal that the time-domain baseband data signal for adding default frame head obtains after analog-to-digital conversion is with pre-
If frame head, when carrying out the demodulation of OTFS signals to the time-domain digital baseband signal, can be achieved by the steps of：
Preamble detecting is carried out to the time-domain digital baseband signal by matched filter；
When detecting frame head, the time-domain digital baseband signal is alignd；
The time-domain digital baseband signal of alignment is subjected to OTFS signal demodulation.
Specifically, after time-domain digital baseband signal is converted digital signals into, by matched filter to the time domain number
Word baseband signal carries out preamble detecting, mathematic(al) representation equation below (3) description of matched filter：
R (t) represents the digital baseband signal received, c*(t) conjugation of time domain header signal is represented,Represent theIt is individual
The output of the matched filter at moment.Therefore work asDuring more than certain pre-determined threshold B, it is believed that default frame head it has been detected that
Follow-up digital baseband transmission system can be carried out after alignment, here with routine signal of communication processing unlike and need not pair
Frequency deviation compensates.So carrying out OTFS signal demodulation after time-domain digital baseband signal is alignd again, OTFS signals are demodulated into
The inverse process of OTFS modulation, therefore after being demodulated by above-mentioned inverse processSignal.
Further, in the present embodiment, due to the particular design method of default pilot tone, simple pungent Fu of two dimension can be passed through
Vertical leaf inverse transformation obtains a kind of channel estimation of the delay Doppler domain comprising effective v and l number.Assuming that corresponding to reception antenna
Digital baseband signal is y (n, t), first by one-dimensional Fourier transform, digital baseband signal corresponding to reception antenna when
Shown in mathematic(al) representation such as formula (4) on frequency domain：
Then the time-frequency domain signal in formula (4) is subjected to two-dimension fourier symplectic transformation and obtains equation below (5),
The channel estimation of the delay Doppler domain as obtained, after as reducing
Further, after channel estimation corresponding to the data signal received is obtained, the channel estimation can be based on, it is determined that
The quantity of mobile target, specifically may include following steps：
Related operation is carried out to the channel estimation, obtains correlation matrix；
Eigenvalues Decomposition is carried out to the correlation matrix, obtains at least one characteristic value；
Based at least one characteristic value, it is determined that the quantity of mobile target.
Wherein, it is described to be based on the characteristic value, it is determined that the quantity of mobile target, including：
Obtain the quantity for the characteristic value for being more than predetermined threshold value at least one characteristic value；
Determine the quantity that the quantity for being more than the characteristic value of predetermined threshold value at least one characteristic value is mobile target.
Specifically, in the present embodiment, it is necessary to channel estimation to acquisitionRelated operation is carried out, computing is using public
Formula (6)：
According to the R in formula (6)μ, φReconstruct correlation matrix Ξ.Eigenvalues Decomposition is carried out to above-mentioned matrix Ξ and obtains formula (7)：
Ξvi=λivi (7)
viRepresent ith feature vector, λiRepresent ith feature value.Above-mentioned Eigenvalues Decomposition can by channel estimation and
Noise is effectively separated on two domains.Secondly as special pilot design has eliminated the influence of static channel, therefore
Remaining channel estimation is the channel of mobile target reflection, and it is larger to move characteristic value corresponding to the launch channel of target, and
Characteristic value corresponding to noise is smaller.Therefore, if eigenvalue λi＞ η, η are predetermined threshold value, then it is assumed that the channel is mobile mesh
The reflected channel of mark, then can confirm that and detect a mobile target.By i=0,1 ..., | v | -1 all characteristic values with
Predetermined threshold value η is compared to obtain final detection target number.It should be noted that DC component causes λ0Be worth it is larger, therefore most
Whole number, which calculates, need to subtract the DC component.
A complete embodiment of Detection of Moving Objects in the present embodiment is given below, refer to Fig. 4, first, hair
Penetrate antenna and reception antenna while work.After radio-frequency module carries out OTFS modulation to pre-set delay Doppler domain symbol, pass through one
Dimension inverse fourier transform is converted to time-domain digital baseband signal, and the time-domain baseband data signal then is added into default frame head, warp
Digital-to-analogue conversion is crossed after data signal, to launch by radio-frequency module to interior.
Indoor mobile target carries out the data signal to reflex to reception antenna, and reception antenna receives the data signal
Afterwards, down-converted and analog-to-digital conversion are carried out to the data signal by radio-frequency module, obtains time-domain digital baseband signal, and will
The time-domain digital baseband signal carries out preamble detecting by matched filter.After frame head is detected, data signal is alignd.
And then the data signal of alignment is carried out to the channel estimation of OTFS signals demodulation acquisition delay Doppler domain, to obtaining
The channel estimation obtained carries out related operation with the conjugation of its own, obtains correlation matrix, and carry out characteristic value to correlation matrix and divide
Solution, finally obtains characteristic value.
Finally, carried out judging the number for moving target according to characteristic value thresholding.When characteristic value is more than predetermined threshold value, i.e. λi
＞ η, it is determined that mobile target be present, and then, if N number of characteristic value is more than predetermined threshold value η, then N number of mobile target be present.
By such mode, by setting special pilot tone, the influence of static channel is eliminated, it is anti-to obtain mobile target
The accurate channel estimation penetrated, and then when carrying out Eigenvalues Decomposition to the matrix of channel estimation reconstruct, can by channel estimation and
Noise is effectively separated on two domains, and then the accurate channel estimation reflected according to mobile target can accurately determine room
The quantity of interior mobile target.Scheme in the present embodiment, require relatively low for radio-frequency module, letter only can be achieved by single antenna
Number transmission and reception, the digital signal structure that radio-frequency module is sent is simple, while has permanent envelope trait, can simplify radio frequency
The design of circuit, reduce the design requirement of radio circuit.And it is possible to being operated in the free frequency ranges of 2.4GHz and 5.8GHz has
Good through-wall performance, it can be ensured that higher accuracy of detection.So the accuracy of detection of mobile target can be effectively improved, drop
The hardware and software cost of low detection.
Fig. 5 is refer to, the second embodiment of the present invention provides a kind of Moving target detection device, and described device includes：
Radio-frequency module 501, for receiving the data signal of the radio-frequency module transmitting, when the data signal is converted to
Domain digital baseband signal, wherein, the data signal is that the radio-frequency module carries out OTFS to pre-set delay Doppler domain symbol
Modulation, then by one-dimensional inverse fourier transform after, to the signal of indoor transmitting after digital-to-analogue conversion；
Channel estimation module 502, for carrying out OTFS signal demodulation to the time-domain digital baseband signal, it is more to obtain delay
The general channel estimation for strangling domain；
Determining module 503, for based on the channel estimation, it is determined that the quantity of mobile target.
Wherein, the pre-set delay Doppler domain symbol is correspondingly arranged on pre-set delay Doppler domain pilot tone, described default
Postpone number of the Doppler domain pilot tone based on Doppler's positive number frequency deviation | ν | and the number of channel latency | l | set, described preset is prolonged
In delay Doppler domain corresponding to slow Doppler domain symbol, real number A and-A are interleaved alternately with delay Doppler domain position x (v, l)
Place, wherein, x (0,0)=A, x (v, 1)=- x (v-1,1), x (1, l)=- x (1, l-1), remaining position is defined as 0.
After the radio-frequency module carries out down-converted and analog-to-digital conversion to the data signal, time-domain digital baseband is obtained
Signal.
Specifically, in this embodiment, the transmitting antenna and reception antenna of radio-frequency module work simultaneously, radio-frequency module is to default
Time-domain digital baseband signal is converted to by one-dimensional inverse fourier transform after the symbol progress OTFS modulation of delay Doppler domain, then passed through
It is data signal to cross digital-to-analogue conversion, launches the data signal to interior by the transmitting antenna of radio-frequency module, if indoor presence
Mobile target, can reflect the data signal, and then the reception antenna of radio-frequency module receives the data signal of reflection, radio frequency mould
After block carries out down-converted and analog-to-digital conversion to the data signal received again, time-domain digital baseband signal is obtained.
Pre-set delay Doppler domain symbol in the present embodiment is that the symbol for needing to carry out OTFS modulation is mapped into delay
The symbol obtained after Doppler domain, pre-set delay Doppler domain symbol are correspondingly arranged on pre-set delay Doppler domain pilot tone, preset
Postpone number of the Doppler domain pilot tone based on Doppler's positive number frequency deviation | v | and channel latency number | l | set, by real number A and-
A is interleaved alternately with the delay corresponding position x (v, l) of Doppler domain, wherein, x (0,0)=A, x (v, 1)=- x (v-1,1) and x
(1, l)=- x (1, l-1), remaining position are defined as 0.Work as v=5, during l=5, pilot design schematic diagram is as shown in Figure 2.The pilot tone
Static channel (channel of non-moving target) effectively can be influenceed effectively to eliminate by design method, be reformed using simplest two
After inverse fourier transform, you can the channel estimation that the static channel that is eliminated influences.
Further, the present embodiment is modulated using OTFS modulator approaches to pre-set delay Doppler domain symbol, and OTFS is adjusted
System is a kind of new type of modulation mode available for 5G communications that cohere companies of the U.S. proposed in 2016.With being used in traditional 4G
OFDM modulation systems it is different, OTFS modulation is that the symbol for needing to modulate has been first mapped into delay Doppler domain, rather than
The frequency domain that conventional OFDM modulation mode is mapped.The symbol that will be mapped to first on delay Doppler domain is by the pungent Fourier of two dimension
Transformed mappings are on whole time-frequency domain.Then by traditional one-dimensional fast fourier inverse transformation, time-domain signal is transformed it into.
Finally, the time-domain signal is gone out after digital-to-analogue conversion is changed into analog signal by radio-frequency transmissions.Whole process with it is traditional
The main distinction of OFDM modulation is exactly that with the addition of a new two-dimentional pungent Fourier transform module, complete OTFS modulated process
As shown in Figure 3.
The pungent Fourier transform of two dimension can use equation below (1) to describe：
Wherein, v is expressed as causing integer Doppler shift by time change channel, and l is expressed as l-th of channel latency, N tables
The number of OFDM symbol is shown as, K is expressed as OFDM subcarrier numbers, and n is expressed as n-th of OFDM symbol moment, and k is expressed as kth
Individual OFDM subcarriers.X (n, k) is expressed as the signal of n-th of moment, k-th of subcarrier, and x (v, l) is expressed as the ν Doppler's frequency
The symbol of the need modulation of l-th of channel latency of integer frequency bias.The symbol can be the constellation symbol such as BPSK of any modulation,
QPSK, QAM etc..
One-dimensional inverse fourier transform can use equation below (2) to describe：
Wherein, x (n, t) is expressed as the signal at t-th of moment within n-th of OFDM symbol time.By formula (1) and public affairs
Formula (2), modulation symbol have transformed to time domain from delay Doppler domain.OTFS is demodulated into the inverse process of OTFS modulation, therefore believes
After road estimation module 502 can be demodulated by above-mentioned inverse processSignal.
Further, in order to accurately receive data signal, in the present embodiment, radio-frequency module is more by pre-set delay
After general Le domain symbol carries out OTFS modulation, then after being converted to time-domain digital baseband signal by one-dimensional inverse fourier transform, also need
Default frame head is added to the time-domain baseband data signal.The default frame head of addition is mainly used in frame detection, is used in the present embodiment
Frame format as shown in figure 3, can use a variety of sequences Designs preset frame head, can be according to actual need in specific implementation process
Set, here, the application is not limited.
And then the data signal that the time-domain baseband data signal for adding default frame head obtains after analog-to-digital conversion is with pre-
If preamble channel estimation module 502 is specifically used for when carrying out the demodulation of OTFS signals to the time-domain digital baseband signal：
Preamble detecting is carried out to the time-domain digital baseband signal by matched filter；
When detecting frame head, the time-domain digital baseband signal is alignd；
The time-domain digital baseband signal of alignment is subjected to OTFS signal demodulation.
Specifically, after radio-frequency module 501 converts digital signals into time-domain digital baseband signal, channel estimation module
502 carry out preamble detecting by matched filter to the time-domain digital baseband signal, and the mathematic(al) representation of matched filter is as follows
Formula (3) describes：
R (t) represents the digital baseband signal received, c*(t) conjugation of time domain header signal is represented,Represent theIt is individual
The output of the matched filter at moment.Therefore work asDuring more than certain pre-determined threshold B, it is believed that default frame head it has been detected that
Follow-up digital baseband transmission system can be carried out after alignment, here with routine signal of communication processing unlike and need not pair
Frequency deviation compensates.So channel estimation module 502 carries out OTFS signal demodulation again after time-domain digital baseband signal is alignd,
OTFS signals are demodulated into the inverse process of OTFS modulation, therefore after being demodulated by above-mentioned inverse processSignal.
Further, in the present embodiment, due to the particular design method of default pilot tone, simple pungent Fu of two dimension can be passed through
Vertical leaf inverse transformation obtains a kind of channel estimation of the delay Doppler domain comprising effective v and l number.Assuming that reception antenna numeral base
Band signal is y (n, t), passes through one-dimensional Fourier transform, mathematics of the reception antenna digital baseband signal on time-frequency domain first
Shown in expression formula such as formula (4)：
Then the time-frequency domain signal in formula (4) is subjected to two-dimension fourier symplectic transformation and obtains equation below (5),
The channel estimation of the delay Doppler domain as obtained, after as reducing
Further, after channel estimation corresponding to the data signal received is obtained, determining module 503 can be based on the letter
Road is estimated, it is determined that the quantity of mobile target, determining module 503 are specifically used for：
Related operation is carried out to the channel estimation, obtains correlation matrix；
Eigenvalues Decomposition is carried out to the correlation matrix, obtains at least one characteristic value；
Based at least one characteristic value, it is determined that the quantity of mobile target.
Wherein, it is described to be based on the characteristic value, it is determined that the quantity of mobile target, including：
Obtain the quantity for the characteristic value for being more than predetermined threshold value at least one characteristic value；
Determine the quantity that the quantity for being more than the characteristic value of predetermined threshold value at least one characteristic value is mobile target.
Specifically, in the present embodiment, determining module 503 needs the channel estimation to acquisitionCarry out related operation,
Computing uses formula (6)：
According to the R in formula (6)μ, φReconstruct correlation matrix Ξ.Eigenvalues Decomposition is carried out to above-mentioned matrix Ξ and obtains formula (7)：
Ξvi=λivi (7)
viRepresent ith feature vector, λiRepresent ith feature value.Above-mentioned Eigenvalues Decomposition can by channel estimation and
Noise is effectively separated on two domains.Secondly as special pilot design has eliminated the influence of static channel, therefore
Remaining channel estimation is the channel of mobile target reflection, and it is larger to move characteristic value corresponding to the launch channel of target, and
Characteristic value corresponding to noise is smaller.Therefore, if it is determined that module 503 determines eigenvalue λi＞ η, η are predetermined threshold value, then it is assumed that
The channel that the channel is reflected for mobile target, then can confirm that and detect a mobile target.By all characteristic values with presetting
Threshold value η is compared to obtain final detection target number.It should be noted that DC component causes λ0It is worth larger therefore final individual
Number calculating need to subtract the DC component.
Said one or multiple technical schemes in the embodiment of the present application, at least there is following one or more technology effects
Fruit：
In the technical scheme of the embodiment of the present invention, radio-frequency module modulates pre-set delay Doppler domain symbol through OTFS,
Transmitting to the interior space, is reflected in the signal of transmitting through mobile target after one-dimensional inverse fourier transform and digital-to-analogue conversion again
Afterwards, radio-frequency module receives corresponding data signal, then passes through OTFS after converting digital signals into time-domain digital baseband signal
Signal is demodulated, channel estimation corresponding to acquisition, then the channel estimation of acquisition is analyzed, you can determines mobile target in space
Quantity.Scheme in the application, require relatively low for radio-frequency module, the transmission of signal only can be achieved by single antenna with connecing
To receive, the digital signal structure that radio-frequency module is sent is simple, while has permanent envelope trait, can simplify the design of radio circuit,
Reduce the design requirement of radio circuit.And it is possible to being operated in the free frequency ranges of 2.4GHz and 5.8GHz has well through walls
Performance, it can be ensured that higher accuracy of detection.So the accuracy of detection of mobile target can be effectively improved, the soft of detection is reduced
Hardware cost.
Although preferred embodiments of the present invention have been described, but those skilled in the art once know basic creation
Property concept, then can make other change and modification to these embodiments.So appended claims be intended to be construed to include it is excellent
Select embodiment and fall into having altered and changing for the scope of the invention.
Obviously, those skilled in the art can carry out the essence of various changes and modification without departing from the present invention to the present invention
God and scope.So, if these modifications and variations of the present invention belong to the scope of the claims in the present invention and its equivalent technologies
Within, then the present invention is also intended to comprising including these changes and modification.
Claims (10)
- A kind of 1. Detection of Moving Objects, it is characterised in that including：The data signal of radio-frequency module transmitting is received, the data signal is converted into time-domain digital baseband signal, wherein, it is described Data signal is the data signal that pre-set delay Doppler domain symbol is generated based on OTFS modulation conversions；OTFS signal demodulation is carried out to the time-domain digital baseband signal, obtains the channel estimation of delay Doppler domain；Based on the channel estimation, it is determined that the quantity of mobile target.
- 2. the method as described in claim 1, it is characterised in that described that the data signal is converted into time-domain digital baseband letter Number, including：After carrying out down-converted and analog-to-digital conversion to the data signal, time-domain digital baseband signal is obtained.
- 3. the method as described in claim 1, it is characterised in that the data signal is described to institute also added with default frame head State time-domain digital baseband signal and carry out OTFS signal demodulation, specifically include：Preamble detecting is carried out to the time-domain digital baseband signal by matched filter；When detecting frame head, the time-domain digital baseband signal is alignd；The time-domain digital baseband signal of alignment is subjected to OTFS signal demodulation.
- 4. the method as described in any claim in claim 1-3, it is characterised in that it is described to be based on the channel estimation, It is determined that the quantity of mobile target, including：Related operation is carried out to the channel estimation, obtains correlation matrix；Eigenvalues Decomposition is carried out to the correlation matrix, obtains at least one characteristic value；Based at least one characteristic value, it is determined that the quantity of mobile target.
- 5. method as claimed in claim 4, it is characterised in that it is described to be based on the characteristic value, it is determined that the quantity of mobile target, Including：Obtain the quantity for the characteristic value for being more than predetermined threshold value at least one characteristic value；Determine the quantity that the quantity for being more than the characteristic value of predetermined threshold value at least one characteristic value is mobile target.
- 6. the method as described in any claim in claim 1-3, it is characterised in that the pre-set delay Doppler domain symbol Number pre-set delay Doppler domain pilot tone is correspondingly arranged on, the pre-set delay Doppler domain pilot tone is based on Doppler's positive number frequency deviation Number | v | and the number of channel latency | l | set, in delay Doppler domain corresponding to the pre-set delay Doppler domain symbol, Real number A and-A is interleaved alternately with delay Doppler domain position x (v, l) place, wherein, x (0,0)=A, x (v, l)=- x (v-1, l), X (1, l)=- x (1, l-1), remaining position is defined as 0.
- 7. a kind of Moving target detection device, it is characterised in that described device includes：Radio-frequency module, for receiving the data signal of the radio-frequency module transmitting, the data signal is converted into time-domain digital Baseband signal, wherein, the data signal is the numeral letter that pre-set delay Doppler domain symbol is generated based on OTFS modulation conversions Number；Channel estimation module, for carrying out OTFS signal demodulation to the time-domain digital baseband signal, obtain delay Doppler domain Channel estimation；Determining module, for based on the channel estimation, it is determined that the quantity of mobile target.
- 8. device as claimed in claim 7, it is characterised in that the data signal is also added with default frame head, the channel Estimation module carries out being specifically used for during the demodulation of OTFS signals to the time-domain digital baseband signal：Preamble detecting is carried out to the time-domain digital baseband signal by matched filter；When detecting frame head, the time-domain digital baseband signal is alignd；The time-domain digital baseband signal of alignment is subjected to OTFS signal demodulation.
- 9. device as claimed in claim 7 or 8, it is characterised in that the determining module based on the channel estimation, it is determined that It is specifically used for during the quantity of mobile target：Related operation is carried out to the channel estimation, obtains correlation matrix；Eigenvalues Decomposition is carried out to the correlation matrix, obtains at least one characteristic value；Based at least one characteristic value, it is determined that the quantity of mobile target；Wherein, it is described to be based on the characteristic value, it is determined that the quantity of mobile target, including：Obtain the quantity for the characteristic value for being more than predetermined threshold value at least one characteristic value；Determine the quantity that the quantity for being more than the characteristic value of predetermined threshold value at least one characteristic value is mobile target.
- 10. device as claimed in claim 7 or 8, it is characterised in that the pre-set delay Doppler domain symbol is correspondingly arranged on Pre-set delay Doppler domain pilot tone, the number of the pre-set delay Doppler domain pilot tone based on Doppler's positive number frequency deviation | v | and letter The number of road delay | l | set, in delay Doppler domain corresponding to the pre-set delay Doppler domain symbol, real number A and-A are handed over Postpone Doppler domain position x (v, l) place for being inserted in, wherein, x (0,0)=A, x (v, 1)=- x (v-1,1), x (1, l)=- x (1, l-1), remaining position are defined as 0.
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