An OBU positioning device and positioning method based on dual receiving channels

Abstract

The invention discloses an OBU positioning device and positioning method based on dual receiving channels. The device comprises: an array antenna for receiving a radio frequency signal sent by an on-board unit (OBU); a selection switch for controlling the connection relationship between each optional antenna unit and a public down-conversion receiving device; a local oscillator signal source for generating a local synchronization signal; a reference down-conversion receiving device for mixing the radio frequency signal received by the reference antenna unit with the local synchronization signal, and performing orthogonal transformation to complete down-conversion processing to obtain a first digital sequence of an I / Q combined baseband signal; a public down-conversion receiving device for obtaining a second digital sequence of the I / Q combined baseband signal; and a positioning device for determining a normalized mutual correlation matrix of two channels when each optional antenna unit is connected, determining an autocorrelation matrix of the array antenna based on the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected, and positioning the OBU based on the autocorrelation matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent transportation and electronic non-stop toll collection, and more particularly to an OBU positioning device and positioning method based on dual receiving channels. Background Art

[0002] The Electronic Toll Collection (ETC) system uses dedicated short-range communication (DSRC) technology to facilitate data exchange between roadside units (RSUs) and on-board units (OBUs). Downlink channels operate at 5.83 GHz and 5.84 GHz, while uplink channels operate at 7.79 GHz and 5.80 GHz. With the widespread adoption of ETC, issues such as interference from adjacent lanes and following vehicles have become increasingly prominent. To address these issues, equipment manufacturers have proposed a variety of solutions. One particularly effective approach is to wirelessly locate the OBU, determining the vehicle's lane and distance from the RSU. This positioning information is then used to guide DSRC transactions.

[0003] In practical applications, two-dimensional positioning methods for OBUs mainly include phased array beam scanning and digital beamforming. Phased array scanning relies on controlling the transmit and receive area of ​​the RF antenna, making it difficult to perform a detailed scan of the lane area in a short period of time. This rough scanning method makes it difficult to achieve high-precision positioning.

[0004] Beamforming-based positioning methods only perform down-conversion reception and A / D conversion on the hardware side, relying on software algorithms for positioning calculations. This method has been used in ETC toll collection systems for many years, but its cost remains the highest in the RSU. Increasing the number of receiving array antenna elements to improve positioning accuracy also increases the number of receiving channels, significantly increasing design complexity and hardware costs, significantly hindering product upgrades.

[0005] Therefore, a dual-receiving channel OBU positioning device and positioning method are needed. Summary of the Invention

[0006] The present invention proposes an OBU positioning device and positioning method based on dual receiving channels to solve the problem of how to complete OBU positioning efficiently.

[0007] In order to solve the above problems, according to one aspect of the present invention, an OBU positioning device based on dual receiving channels is provided, the device comprising: an array antenna, a gating switch, a local oscillator signal source, a reference down-conversion receiving device, a public down-conversion receiving device and a positioning device; wherein,

[0008] The array antenna comprises: at least three antenna units, one antenna unit is selected as a reference antenna unit, and the remaining antenna units are selected as optional antenna units, the reference antenna unit is connected to the reference down-conversion receiving device, the optional antenna unit is connected to the public down-conversion receiving device through the selection switch, and the array antenna is used to receive the radio frequency signal sent by the on-board unit OBU;

[0009] The gating switch is used to control the connection relationship between each optional antenna unit and the public down-conversion receiving device;

[0010] The local oscillator signal source is connected to the reference down-conversion receiving device and the public down-conversion receiving device respectively, and is used to generate local synchronization signals required by the reference down-conversion receiving device and the public down-conversion receiving device;

[0011] The reference down-conversion receiving device is connected to the positioning device and is used to mix the radio frequency signal received by the reference antenna unit and the local synchronization signal, and perform orthogonal transformation to complete down-conversion processing to obtain a first digital sequence of the baseband signal I / Q combination;

[0012] The public down-conversion receiving device is connected to the positioning device and is used to mix the radio frequency signal received by the optional antenna unit and the local synchronization signal, and perform orthogonal transformation to complete down-conversion processing to obtain a second digital sequence of the baseband signal I / Q combination;

[0013] The positioning device is used to determine the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected based on the first digital sequence and the second digital sequence, determine the autocorrelation matrix of the array antenna based on the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected, and locate the OBU based on the autocorrelation matrix.

[0014] Preferably, the array antenna is in an L-shaped, straight-shaped or cross-shaped array.

[0015] Preferably, the reference down-conversion receiving device and the common down-conversion receiving device both comprise: a low noise amplifier LNA, a mixer, a filter, an intermediate frequency amplifier and an analog-to-digital AD conversion module connected in sequence.

[0016] Preferably, the reference down-conversion receiving device and the common down-conversion receiving device obtain the digital sequence in the following manner, including:

[0017] The radio frequency signal is amplified by a low noise amplifier LAN and then mixed with a local synchronization signal, and after mixing, filtered, amplified, A / D converted, and digitally orthogonally transformed in sequence to obtain a digital in-phase component I and a digital quadrature component Q, so as to obtain a digital sequence of a baseband signal I / Q combined after orthogonal transformation based on the digital in-phase component I and the digital quadrature component Q; or

[0018] The RF signal is amplified by a low-noise amplifier LAN and then subjected to orthogonal mixing with a local synchronization signal to obtain an analog in-phase component I and an analog quadrature component Q. The analog in-phase component I and the analog quadrature component Q are filtered, amplified, and A / D converted in sequence to obtain a digital in-phase component I and a digital quadrature component Q. A digital sequence of a baseband signal I / Q merged after orthogonal transformation is obtained based on the digital in-phase component I and the digital quadrature component Q.

[0019] Preferably, the positioning device determines the normalized mutual correlation matrix of two channels when each optional antenna unit is connected according to the first digital sequence and the second digital sequence, including:

[0020]

[0021] Among them, R′ sn is the normalized cross-correlation matrix of the two channels when the nth optional antenna unit is connected; C n is the normalization coefficient; X s is the first digital sequence, X n is the second digital sequence; is the conjugate of the first number sequence; is the conjugate of the second digital sequence; A n is the amplitude of the optional antenna element No. n; is the phase of the optional antenna unit No. n; A s is the amplitude of the reference antenna unit; the phase of the reference antenna unit is the 0 phase point.

[0022] Preferably, the positioning device determines the autocorrelation matrix of the array antenna based on the normalized mutual correlation matrix of the two channels when each optional antenna unit is accessed, and locates the OBU based on the autocorrelation matrix, including:

[0023] Determining the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of the two channels when each optional antenna unit is connected;

[0024] Calculate the power spectrum based on the autocorrelation matrix, and select the angle corresponding to the maximum value of the power spectrum as the incident angle θ of the OBU;

[0025] Locate the OBU according to the installation information of the roadside unit RSU and the incident angle θ, and determine the coordinate information of the OBU;

[0026] Among them, the method for determining the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of two channels when each optional antenna unit is accessed includes:

[0027]

[0028] Among them, R xx is the autocorrelation matrix; the empty element in the i-th row and j-th column of the upper triangular part of the autocorrelation matrix is: 1 ≤ i < j ≤ N; the empty element in the j-th row and i-th column of the lower triangular part of the autocorrelation matrix is: * represents conjugate.

[0029] According to another aspect of the present invention, there is provided an OBU positioning method based on the above-mentioned OBU positioning device based on dual receiving channels, and the method includes:

[0030] Step 1, the array antenna receives the radio frequency signal sent by the on-vehicle unit OBU, and sends it to the reference down-conversion receiving device and the common down-conversion receiving device respectively; among them, the array antenna includes: at least three antenna units, select one antenna unit as the reference antenna unit, and the remaining antenna units as optional antenna units;

[0031] Step 2, initialize i = 1;

[0032] Step 3, the selection switch controls the i-th optional antenna unit to be connected to the common down-conversion receiving device;

[0033] Step 4, the local oscillator signal source generates the local synchronization signals required by the reference down-conversion receiving device and the common down-conversion receiving device;

[0034] Step 5, the reference down-conversion receiving device mixes the radio frequency signal received by the reference antenna unit and the local synchronization signal, and performs orthogonal transformation to complete the down-conversion process to obtain the first digital sequence of the baseband signal I / Q combination; the common down-conversion receiving device mixes the radio frequency signal received by the optional antenna unit and the local synchronization signal, and performs orthogonal transformation to complete the down-conversion process to obtain the second digital sequence of the baseband signal I / Q combination;

[0035] Step 6: The positioning device determines the cross-correlation matrix between the i-th optional antenna unit and the reference antenna unit based on the first digital sequence and the second digital sequence when the i-th optional antenna unit is connected, and determines whether i is less than or equal to N. If so, execute i = i + 1 and return to step 3; otherwise, proceed to step 7; where N is the number of optional antenna units;

[0036] Step 7: The positioning device determines the autocorrelation matrix of the array antenna according to the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected, and locates the OBU based on the autocorrelation matrix.

[0037] Preferably, the reference down-conversion receiving device and the common down-conversion receiving device both comprise: a low noise amplifier LNA, a mixer, a filter, an intermediate frequency amplifier and an analog-to-digital AD conversion module connected in sequence.

[0038] Preferably, the reference down-conversion receiving device and the common down-conversion receiving device obtain the digital sequence in the following manner, including:

[0039] The radio frequency signal is amplified by a low noise amplifier LAN and then mixed with a local synchronization signal, and after mixing, filtered, amplified, A / D converted, and digitally orthogonally transformed in sequence to obtain a digital in-phase component I and a digital quadrature component Q, so as to obtain a digital sequence of a baseband signal I / Q combined after orthogonal transformation based on the digital in-phase component I and the digital quadrature component Q; or

[0040] The RF signal is amplified by a low-noise amplifier LAN and then subjected to orthogonal mixing with a local synchronization signal to obtain an analog in-phase component I and an analog quadrature component Q. The analog in-phase component I and the analog quadrature component Q are filtered, amplified, and A / D converted in sequence to obtain a digital in-phase component I and a digital quadrature component Q. A digital sequence of a baseband signal I / Q merged after orthogonal transformation is obtained based on the digital in-phase component I and the digital quadrature component Q.

[0041] Preferably, the positioning device determines a normalized mutual correlation matrix between the i-th optional antenna unit and the reference antenna unit based on the first digital sequence and the second digital sequence when the i-th optional antenna unit is connected, including:

[0042]

[0043] Among them, R′ sn is the normalized cross-correlation matrix of the two channels when the nth optional antenna unit is connected; C n is the normalization coefficient; X s is the first digital sequence, X n is the second digital sequence; is the conjugate of the first number sequence; is the conjugate of the second digital sequence; A n is the amplitude of the nth optional antenna unit; is the phase of the nth optional antenna unit; A s is the amplitude of the reference antenna unit; the phase of the reference antenna unit is the zero-phase point.

[0044] Preferably, the positioning device determines the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of two channels when each optional antenna unit accesses, and performs positioning of the OBU based on the autocorrelation matrix, including:

[0045] Determine the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of two channels when each optional antenna unit accesses;

[0046] Calculate the power spectrum based on the autocorrelation matrix, and select the angle corresponding to the maximum value of the power spectrum as the incident angle θ of the OBU; perform positioning of the OBU according to the installation information of the roadside unit RSU and the incident angle θ to determine the coordinate information of the OBU;

[0047] Among them, the determining the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of two channels when each optional antenna unit accesses includes:

[0048]

[0049] Among them, R xx is the autocorrelation matrix; the empty element in the i-th row and j-th column of the upper triangular part of the autocorrelation matrix is: 1≤i<j≤N; the empty element in the j-th row and i-th column of the lower triangular part of the autocorrelation matrix is: * represents conjugate.

[0050] The present invention provides an OBU positioning device and positioning method based on dual receiving channels. The device comprises: an array antenna, comprising: at least three antenna units, one antenna unit is selected as a reference antenna unit, and the remaining antenna units are selected as optional antenna units, for receiving radio frequency signals sent by an on-board unit (OBU); a selection switch, for controlling the connection relationship between each optional antenna unit and the common down-conversion receiving device; a local oscillator signal source, for generating a local synchronization signal; a reference down-conversion receiving device, for mixing the radio frequency signal received by the reference antenna unit and the local synchronization signal, and performing orthogonal transformation to complete down-conversion. Processing to obtain a first digital sequence of baseband signal I / Q combination; a public down-conversion receiving device for mixing the radio frequency signal received by the optional antenna unit with the local synchronization signal, and performing orthogonal transformation to complete down-conversion processing to obtain a second digital sequence of baseband signal I / Q combination; a positioning device for determining the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected based on the first digital sequence and the second digital sequence, determining the autocorrelation matrix of the array antenna based on the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected, and locating the OBU based on the autocorrelation matrix. The present invention only requires two down-conversion receiving channels, and synchronous down-conversion and positioning calculation of the array signal can be achieved by switching the antenna units by a gating switch. Compared with the existing technology, the hardware complexity and cost of the receiver can be greatly reduced, it can flexibly adapt to various different array antennas, and the positioning resolution and accuracy can be improved by increasing the number of antenna units. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0052] Figure 1 Schematic diagram of the structure of an OBU positioning device 100 based on dual receiving channels according to an embodiment of the present invention;

[0053] Figure 2 A schematic diagram of the connection relationship of an OBU positioning device according to an embodiment of the present invention;

[0054] Figure 3 Schematic diagram of a linear array antenna including five antenna elements according to an embodiment of the present invention;

[0055] Figure 4 Schematic diagram of an L-shaped array including 9 antenna units according to an embodiment of the present invention.

[0056] Figure 5 is a schematic diagram of a gating switch including seven switches when there are four optional antenna units according to an embodiment of the present invention;

[0057] Figure 6 is a schematic diagram of a gating switch including three switches when there are four optional antenna units according to an embodiment of the present invention;

[0058] Figure 7 A schematic diagram of a process of analog down-conversion processing and obtaining a digital signal according to an embodiment of the present invention;

[0059] Figure 8 A schematic diagram of a process of simulating quadrature down-conversion processing and acquiring a digital signal according to an embodiment of the present invention;

[0060] Figure 9 A schematic diagram of an array antenna receiving a signal according to an embodiment of the present invention;

[0061] Figure 10 Flowchart of an OBU positioning method 1000 based on dual receiving channels according to an embodiment of the present invention. DETAILED DESCRIPTION

[0062] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0063] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0064] Figure 1 FIG. 1 is a schematic structural diagram of an OBU positioning device 100 based on dual receiving channels according to an embodiment of the present invention. Figure 1 As shown, the dual-receiving-channel OBU positioning device provided by the embodiment of the present invention only requires two down-conversion receiving channels. By switching the antenna units through the gating switch, the synchronous down-conversion and positioning calculation of the array signal can be achieved. Compared with the existing technology, the hardware complexity and cost of the receiver can be greatly reduced, and it can be flexibly adapted to various different array antennas. The positioning resolution and positioning accuracy can also be improved by increasing the number of antenna units. The dual-receiving-channel OBU positioning device 100 provided by the embodiment of the present invention includes: an array antenna 101, a gating switch 102, a local oscillator signal source 103, a reference down-conversion receiving device 104, a common down-conversion receiving device 105, and a positioning device 106.

[0065] Preferably, the array antenna 101 includes: at least three antenna units, one antenna unit is selected as a reference antenna unit, and the remaining antenna units are selected as optional antenna units, the reference antenna unit is connected to the reference down-conversion receiving device, and the optional antenna unit is connected to the public down-conversion receiving device through the selection switch, and the array antenna is used to receive the radio frequency signal sent by the on-board unit OBU.

[0066] Preferably, the array antenna is in an L-shaped, straight-shaped or cross-shaped array.

[0067] Combine Figure 2 As shown, in the present invention, the positioning device includes an array antenna, a gate switch, a local oscillator signal source, a down-conversion receiving device, an AD conversion module and a positioning device. The positioning device can process digital signals.

[0068] In the present invention, the array antenna is composed of multiple identical antenna units, one of which is a reference antenna unit connected to a reference down-conversion receiving device, and the other optional antenna units are connected to a selection switch and share a common down-conversion receiving device. The reference antenna unit is fixedly connected to the reference down-conversion receiving device, and the multiple optional antenna units are connected to the common down-conversion receiving device via the selection switch. The array antenna is capable of receiving radio frequency signals transmitted by an on-board unit (OBU). The array antenna includes at least three antenna units, and the array can be in a straight line, L-shaped, cross-shaped, or any other arbitrary shape.

[0069] like Figure 3 As shown, the array antenna is a one-dimensional uniform linear array with 5 elements and an antenna spacing of d, where antenna s is the reference antenna element and antennas 1-4 are optional antenna elements. Figure 4 As shown, the array antenna consists of 9 antenna units, the horizontal optional antenna units are antennas 1-4, the vertical optional antenna units are antennas 5-8, the point antenna s is the reference antenna unit, and the horizontal and vertical spacing is d.

[0070] Preferably, the selection switch 102 is used to control the connection relationship between each optional antenna unit and the public down-conversion receiving device.

[0071] In the present invention, the gating switch can be composed of an RF switch or an RF switch and a combiner. The gating switch is used to control the optional antenna units to be connected to a common down-conversion receiving device, so as to sequentially perform down-conversion processing and A / D conversion. Based on the converted signals, the normalized cross-correlation matrix of the two channels when each optional antenna unit is connected is calculated for positioning the OBU.

[0072] like Figure 5Figure 2 shows a schematic diagram of a seven-switch selection switch for four selectable antenna units. The selection switch consists of two selectable RF switches, S1-S7. One input of S4-S7 is connected to an optional antenna unit, and the other input is connected to ground. At any given time, only one of S4-S7 switches is selected for selection. The other three switches are connected to ground to prevent interference between the signals received by the antenna units and improve isolation between the input antenna units.

[0073] like Figure 6 Figure 2 shows a schematic diagram of a three-switch gating switch for four selectable antenna units. If the isolation of the two-to-one RF switch is good, only S1-S3 can be used to implement the gating switch, with the antenna units connected to the inputs of S2 and S3.

[0074] Preferably, the local oscillator signal source 103 is connected to the reference down-conversion receiving device and the public down-conversion receiving device respectively, and is used to generate local synchronization signals required by the reference down-conversion receiving device and the public down-conversion receiving device.

[0075] In the present invention, the local oscillator signal source can generate local synchronization signals required by two down-conversion receiving devices.

[0076] Preferably, the reference down-conversion receiving device 104 is connected to the positioning device, and is used to mix the radio frequency signal received by the reference antenna unit and the local synchronization signal, and perform orthogonal transformation to complete the down-conversion processing to obtain the first digital sequence of the baseband signal I / Q combination.

[0077] Preferably, the public down-conversion receiving device 105 is connected to the positioning device and is used to mix the radio frequency signal received by the optional antenna unit and the local synchronization signal, and perform orthogonal transformation to complete the down-conversion processing to obtain a second digital sequence of the baseband signal I / Q combination.

[0078] Preferably, the reference down-conversion receiving device 104 and the common down-conversion receiving device 105 both include: a low noise amplifier LNA, a mixer, a filter, an intermediate frequency amplifier and an analog-to-digital AD conversion module connected in sequence.

[0079] In the present invention, down-conversion processing is performed by a reference down-conversion receiving device and a common down-conversion receiving device to convert the radio frequency signal into an intermediate frequency signal, or into an orthogonal zero intermediate frequency signal for use in AD conversion and positioning calculation.

[0080] In the present invention, two analog-to-digital AD conversion modules are used to convert the low-frequency analog signal (intermediate frequency signal or zero intermediate frequency signal) generated by the down-conversion receiving device into a digital signal, and the AD conversion clocks of the two down-conversion receiving devices are synchronized.

[0081] In the present invention, both the reference down-conversion receiving device and the common down-conversion receiving device are composed of a low noise amplifier (LNA), a mixer, a filter, an intermediate frequency amplifier, and an analog-to-digital (AD) conversion module.

[0082] Figure 7 FIG. 1 is a schematic diagram of a process for analog down-conversion processing and obtaining a digital signal according to an embodiment of the present invention. Figure 7 As shown, the down-conversion receiving device only completes the down-conversion processing. The down-conversion receiving device is composed of a low-noise amplifier LNA, mixing, filtering, amplification and analog-to-digital AD conversion module. The RF signal coming from the antenna unit is first mixed with the local synchronization signal, and then filtered to obtain the intermediate frequency signal. The intermediate frequency signal is then amplified and sent to the AD converter for collection. An orthogonal transformation is performed in a digital signal processor such as FPGA or DSP to obtain the in-phase component I and the orthogonal component Q, which form a complex digital sequence and are input to the positioning device for positioning.

[0083] Figure 8 FIG. 1 is a schematic diagram of a process for simulating orthogonal down-conversion processing and obtaining a digital signal according to an embodiment of the present invention. Figure 8 As shown, the down-conversion receiving device completes the down-conversion processing and orthogonal transformation of the signal. The down-conversion device consists of a low-noise amplifier (LNA), orthogonal mixing, filtering, and amplification. The signal coming from the antenna unit is first orthogonally mixed with the local synchronization signal to obtain analog in-phase component I and orthogonal component Q. After filtering, it is sent to AD conversion for collection, forming a complex digital sequence that enters a digital signal processor such as FPGA or DSP (i.e., positioning device) for positioning.

[0084] Preferably, the positioning device 106 is used to determine the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected based on the first digital sequence and the second digital sequence, determine the autocorrelation matrix of the array antenna based on the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected, and locate the OBU based on the autocorrelation matrix.

[0085] Preferably, the positioning device 106 determines the normalized mutual correlation matrix of two channels when each optional antenna unit is connected according to the first digital sequence and the second digital sequence, including:

[0086]

[0087] Among them, R′ sn is the normalized cross-correlation matrix of the two channels when the nth optional antenna unit is connected; C n is the normalization coefficient; X s is the first digital sequence, X n is the second digital sequence; is the conjugate of the first number sequence; is the conjugate of the second digital sequence; A n is the amplitude of the nth optional antenna unit; is the phase of the nth optional antenna unit; A s is the amplitude of the reference antenna unit; the phase of the reference antenna unit is the zero-phase point.[[ID=...]] [[ID=...]]

[0088] Preferably, the positioning device determines the autocorrelation matrix of the array antenna based on the normalized cross-correlation matrix of two channels when each optional antenna unit accesses, and performs the positioning of the OBU based on the autocorrelation matrix, including:

[0089] Determine the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of two channels when each optional antenna unit accesses;

[0090] Calculate the power spectrum based on the autocorrelation matrix, and select the angle corresponding to the maximum value of the power spectrum as the incident angle θ of the OBU; perform the positioning of the OBU according to the installation information of the roadside unit RSU and the incident angle θ, and determine the coordinate information of the OBU;

[0091] Among them, the determining the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of two channels when each optional antenna unit accesses includes:

[0092]

[0093] Among them, R xx is the autocorrelation matrix; the empty element in the i-th row and j-th column of the upper triangular part of the autocorrelation matrix is: 1 ≤ i < j ≤ N; the empty element in the j-th row and i-th column of the lower triangular part of the autocorrelation matrix is: * represents the conjugate.

[0094] In the present invention, the positioning device is mainly used to complete algorithm processing and OBU positioning, and output positioning results. The positioning device can also control the selection switch to sequentially collect the signals of each optional antenna unit, and configure the local oscillator signal source to generate a suitable mixing signal.

[0095] Combined with Figure 9 As shown, in the present invention, the array antenna is a uniform linear array composed of 1 reference antenna unit and N optional antenna units, and the received signal is X s 、X1、X2、…、X N , the incident angle of the target OBU is θ, the distance between antenna units is d, and the distance differences between the incident signal and the N optional antenna units and the reference antenna unit are L1, L2, …, L N .

[0096] Let the phase of the reference antenna unit is the 0 phase point, and the phases of the optional antenna units are Then we have:

[0097]

[0098] The signal received by the antenna unit is converted into a complex digital sequence of orthogonal zero intermediate frequency after analog and digital processing. The phase difference caused by the line between each antenna unit and the orthogonal transformation is eliminated by delay calibration. Suppose the signal sequence of the reference down-conversion receiving device is X s , the signal sequence of the public down-conversion receiving device is X1-X N , then the digital sequence of each antenna unit can be expressed as:

[0099]

[0100] Among them, a(k) is the baseband waveform coefficient of ASK modulation. At the same time, all receiving antenna units are the same, A s , A1, A2, …, A N is the amplitude of each receiving antenna element.

[0101] Control the selection switch to allow the signal of the nth optional antenna unit to enter the public down-conversion receiving device, synchronously collect the data of the K-point reference down-conversion receiving device and the public down-conversion receiving device, and obtain the cross-correlation matrix of the two channels:

[0102]

[0103]

[0104] make R sn Perform normalization to obtain the normalized cross-correlation matrix:

[0105]

[0106] In practical applications, the normalized cross-correlation matrix obtained based on the n optional antenna units can be expressed as:

[0107]

[0108] Among them, a n 、b n 、r nn The signal sent by the OBU will last for a certain period of time, quickly switch the selection switch, and calculate the normalized cross-correlation matrix R' of all optional antenna units and the reference antenna unit. s1 , R′ s2 ,…,R′ sN .

[0109] Then use N second-order cross-correlation matrices to form the autocorrelation matrix R of the entire array antenna xx :

[0110]

[0111] Directly composed R xx Only the elements in the first row, first column, and diagonal have values, and the rest are empty. In the case of a good signal-to-noise ratio, the elements in other places can be deduced from the known elements. The calculation method for the empty elements in the upper triangle is:

[0112]

[0113] Since R xx The conjugate transpose of is equal to itself, so the empty element in the lower triangle is the conjugate of its symmetric element, that is:

[0114]

[0115] set up The weighting coefficient of the direction is

[0116]

[0117] The power spectrum is obtained by using the delay-and-add beamforming algorithm:

[0118]

[0119] Select the value corresponding to the maximum value of the power spectrum That is the incident angle θ of the target OBU.

[0120] Finally, combined with the RSU installation information, the coordinates of the target OBU can be calculated to achieve positioning.

[0121] In the present invention, in addition to the delay-and-add method, algorithms with higher resolutions such as Capon and Music can also be used to calculate the incident angle of the target OBU.

[0122] by Figure 5 Taking the array antenna as an example, control the selection switch so that antennas 1-4 pass through the public down-conversion receiving device in turn, and calculate the cross-correlation matrix R' of each optional antenna unit and the reference antenna unit s1 -R′ s4 , and get the autocorrelation matrix of the entire array antenna:

[0123]

[0124] Weighting coefficient for:

[0125]

[0126] Compute the power spectrum using a beamforming algorithm: The angle corresponding to the maximum value of the power spectrum is selected as the desired direction angle.

[0127] by Figure 6 Taking the array antenna as an example, switch the selection switch to make antennas 1-8 enter the public down-conversion receiving device respectively, and calculate 8 second-order cross-correlation matrices R′ s1 -R′ s8 , and find the autocorrelation matrix of the entire array antenna:

[0128]

[0129] Assume the horizontal scanning angle is The longitudinal scanning angle is β, let The weighting coefficient is:

[0130]

[0131] The power spectrum of the beamforming algorithm is:

[0132]

[0133] Angle corresponding to the maximum value of the power spectrum β is the lateral and longitudinal incident angle of the target OBU. Combined with the actual installation parameters of the RSU, the direction angle is converted into lane coordinates to obtain the two-dimensional coordinates of the OBU and achieve positioning.

[0134] In the present invention, the positioning step of OBU is:

[0135] 1. Wait to receive the signal transmitted by the OBU. When the preamble and frame header are decoded, the positioning process begins.

[0136] 2. Control the selection switch to connect the first optional antenna unit to the public down-conversion receiving device.

[0137] 3. Synchronously collect the signals output by the reference down-conversion receiving device and the common down-conversion receiving device, and calculate the normalized cross-correlation matrix of the two channels.

[0138] 4. Repeat step 3 to complete down-conversion and AD conversion for all optional antenna units, and calculate the normalized cross-correlation matrix.

[0139] 5. The N optional antenna units obtain N second-order normalized cross-correlation matrices, and then the autocorrelation matrix of the entire array antenna is calculated and positioning calculations are performed to obtain the direction angle of the target OBU.

[0140] 6. According to the actual installation parameters of the RSU, the direction angle is converted into lane coordinates and the positioning result is output.

[0141] Figure 10 Flowchart of the OBU positioning method based on dual receiving channels according to an embodiment of the present invention. Figure 10 As shown, the OBU positioning method 1000 based on the dual receiving channel of the OBU positioning device based on the above-mentioned dual receiving channel provided in an embodiment of the present invention starts from step 1001. In step 1001, the array antenna receives the radio frequency signal sent by the on-board unit OBU and sends it to the reference down-conversion receiving device and the public down-conversion receiving device respectively; wherein, the method includes: at least three antenna units, one antenna unit is selected as the reference antenna unit, and the remaining antenna units are selected as optional antenna units.

[0142] In step 1002, i=1 is initialized.

[0143] In step 1003, the selection switch controls the i-th optional antenna unit to be connected to the public down-conversion receiving device.

[0144] In step 1004, a local oscillator signal source generates a local synchronization signal required by the reference down-conversion receiving device and the common down-conversion receiving device.

[0145] In step 1005, the reference down-conversion receiving device mixes the radio frequency signal received by the reference antenna unit and the local synchronization signal, and performs orthogonal transformation to complete the down-conversion processing to obtain a first digital sequence of the baseband signal I / Q combination; the public down-conversion receiving device mixes the radio frequency signal received by the optional antenna unit and the local synchronization signal, and performs orthogonal transformation to complete the down-conversion processing to obtain a second digital sequence of the baseband signal I / Q combination.

[0146] Preferably, the reference down-conversion receiving device and the common down-conversion receiving device both comprise: a low noise amplifier LNA, a mixer, a filter, an intermediate frequency amplifier and an analog-to-digital AD conversion module connected in sequence.

[0147] Preferably, the reference down-conversion receiving device and the common down-conversion receiving device obtain the digital sequence in the following manner, including:

[0148] The radio frequency signal is amplified by a low noise amplifier LAN and then mixed with a local synchronization signal, and after mixing, filtered, amplified, A / D converted, and digitally orthogonally transformed in sequence to obtain a digital in-phase component I and a digital quadrature component Q, so as to obtain a digital sequence of a baseband signal I / Q combined after orthogonal transformation based on the digital in-phase component I and the digital quadrature component Q; or

[0149] The RF signal is amplified by a low-noise amplifier LAN and then subjected to orthogonal mixing with a local synchronization signal to obtain an analog in-phase component I and an analog quadrature component Q. The analog in-phase component I and the analog quadrature component Q are filtered, amplified, and A / D converted in sequence to obtain a digital in-phase component I and a digital quadrature component Q. A digital sequence of a baseband signal I / Q merged after orthogonal transformation is obtained based on the digital in-phase component I and the digital quadrature component Q.

[0150] In step 1006, the positioning device determines the cross-correlation matrix between the i-th optional antenna unit and the reference antenna unit based on the first digital sequence and the second digital sequence when the i-th optional antenna unit is connected, and determines whether i is less than or equal to N. If so, execute i=i+1 and return to step 1003; otherwise, enter step 1007; where N is the number of optional antenna units.

[0151] Preferably, the positioning device determines the mutual correlation matrix between the i-th optional antenna unit and the reference antenna unit based on the first digital sequence and the second digital sequence when the i-th optional antenna unit is connected, including:

[0152] Among them, R′ sn is the normalized cross-correlation matrix of the two channels when the nth optional antenna unit is connected; C n is the normalization coefficient; X s is the first digital sequence, X n is the second digital sequence; is the conjugate of the first number sequence; is the conjugate of the second digital sequence; A n is the amplitude of the optional antenna element No. n; is the phase of the optional antenna unit No. n; A s is the amplitude of the reference antenna unit; the phase of the reference antenna unit is the 0 phase point.

[0153] In step 1007, the positioning device determines the autocorrelation matrix of the array antenna according to the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected, and locates the OBU based on the autocorrelation matrix.

[0154] Preferably, the positioning device determines the autocorrelation matrix of the array antenna according to the normalized mutual correlation matrix of the two channels when each optional antenna unit is accessed, and locates the OBU based on the autocorrelation matrix, including:

[0155] Determining the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of the two channels when each optional antenna unit is connected;

[0156] Calculate the power spectrum based on the autocorrelation matrix, and select the angle corresponding to the maximum value of the power spectrum as the incident angle θ of the OBU;

[0157] Locate the OBU according to the installation information of the roadside unit RSU and the incident angle θ, and determine the coordinate information of the OBU;

[0158] Among them, the method for determining the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of two channels when each optional antenna unit is accessed includes:

[0159]

[0160] Among them, R xx is the autocorrelation matrix; the empty element in the i-th row and j-th column of the upper triangular part of the autocorrelation matrix is: 1 ≤ i < j ≤ N; the empty element in the j-th row and i-th column of the lower triangular part of the autocorrelation matrix is: * represents conjugation.

[0161] The OBU positioning method 1,000 based on dual receiving channels in the embodiments of the present invention corresponds to the OBU positioning device 100 based on dual receiving channels in another embodiment of the present invention, and will not be elaborated here.

[0162] The present invention has been described by referring to a few embodiments. However, as is well known to those skilled in the art, as defined by the appended patent claims, other embodiments equivalent to those disclosed above of the present invention equally fall within the scope of the present invention.

[0163] Generally, all terms used in the claims are construed according to their ordinary meanings in the technical field, unless otherwise clearly defined therein. All references to "a / the [device, component, etc.]" are to be construed openly as at least one instance of the device, component, etc., unless otherwise clearly stated. The steps of any method disclosed herein need not be performed in the exact order disclosed, unless clearly stated.

[0164] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

[0165] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0166] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0167] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0168] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. An OBU positioning device based on dual receiving channels, characterized in that: The device comprises: an array antenna, a gating switch, a local oscillator signal source, a reference down-conversion receiving device, a public down-conversion receiving device and a positioning device; wherein, The array antenna comprises: at least three antenna units, one antenna unit is selected as a reference antenna unit, and the remaining antenna units are selected as optional antenna units, the reference antenna unit is connected to the reference down-conversion receiving device, the optional antenna unit is connected to the public down-conversion receiving device through the selection switch, and the array antenna is used to receive the radio frequency signal sent by the on-board unit OBU; The gating switch is used to control the connection relationship between each optional antenna unit and the public down-conversion receiving device; The local oscillator signal source is connected to the reference down-conversion receiving device and the public down-conversion receiving device respectively, and is used to generate local synchronization signals required by the reference down-conversion receiving device and the public down-conversion receiving device; The reference down-conversion receiving device is connected to the positioning device and is used to mix the radio frequency signal received by the reference antenna unit and the local synchronization signal, and perform orthogonal transformation to complete down-conversion processing to obtain a first digital sequence of the baseband signal I / Q combination; The public down-conversion receiving device is connected to the positioning device and is used to mix the radio frequency signal received by the optional antenna unit and the local synchronization signal, and perform orthogonal transformation to complete down-conversion processing to obtain a second digital sequence of the baseband signal I / Q combination; The positioning device is used to determine the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected based on the first digital sequence and the second digital sequence, determine the autocorrelation matrix of the array antenna based on the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected, and locate the OBU based on the autocorrelation matrix.

2. The device according to claim 1, characterized in that The array antenna is in an L-shaped, straight-shaped or cross-shaped array.

3. The device according to claim 1, characterized in that The reference down-conversion receiving device and the common down-conversion receiving device both include: a low noise amplifier LNA, a mixer, a filter, an intermediate frequency amplifier and an analog-to-digital AD conversion module connected in sequence.

4. The device according to claim 3, characterized in that The reference down-conversion receiving device and the common down-conversion receiving device obtain the digital sequence in the following manner, including: The radio frequency signal is amplified by a low noise amplifier LAN and then mixed with a local synchronization signal, and after mixing, filtered, amplified, A / D converted, and digitally orthogonally transformed in sequence to obtain a digital in-phase component I and a digital quadrature component Q, so as to obtain a digital sequence of a baseband signal I / Q combined after orthogonal transformation based on the digital in-phase component I and the digital quadrature component Q; or The RF signal is amplified by a low-noise amplifier LAN and then subjected to orthogonal mixing with a local synchronization signal to obtain an analog in-phase component I and an analog quadrature component Q. The analog in-phase component I and the analog quadrature component Q are filtered, amplified, and A / D converted in sequence to obtain a digital in-phase component I and a digital quadrature component Q. A digital sequence of a baseband signal I / Q merged after orthogonal transformation is obtained based on the digital in-phase component I and the digital quadrature component Q.

5. The device according to claim 1, characterized in that The positioning device determines, according to the first digital sequence and the second digital sequence, a normalized mutual correlation matrix of two channels when each optional antenna unit is connected, including: Among them, R′ sn is the normalized cross-correlation matrix of the two channels when the nth optional antenna unit is connected; C n is the normalization coefficient; X s is the first digital sequence, X n is the second digital sequence; is the conjugate of the first number sequence; is the conjugate of the second digital sequence; A n is the amplitude of the optional antenna element No. n; is the phase of the optional antenna unit No. n; A s is the amplitude of the reference antenna unit; the phase of the reference antenna unit is the 0 phase point.

6. The device according to claim 1, characterized in that The positioning device determines the autocorrelation matrix of the array antenna based on the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected, and locates the OBU based on the autocorrelation matrix, including: Determining the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of the two channels when each optional antenna unit is connected; Calculate the power spectrum based on the autocorrelation matrix, and select the angle corresponding to the maximum value of the power spectrum as the incident angle θ of the OBU; Positioning the OBU according to the installation information of the roadside unit RSU and the incident angle θ to determine the coordinate information of the OBU; The step of determining the autocorrelation matrix of the array antenna according to the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected includes: Among them, R xx is the autocorrelation matrix; the empty element in the upper triangle of the i-th row and j-th column in the autocorrelation matrix is: The empty element in the jth row and ith column of the lower triangle of the autocorrelation matrix is: * indicates conjugation.

7. An OBU positioning method based on a dual receiving channel based on the OBU positioning device based on a dual receiving channel according to any one of claims 1 to 6, characterized in that: The method comprises: Step 1: The array antenna receives the radio frequency signal sent by the on-board unit (OBU) and sends it to a reference down-conversion receiving device and a common down-conversion receiving device respectively; wherein, the array antenna includes at least three antenna units, one antenna unit is selected as a reference antenna unit, and the remaining antenna units are selected as optional antenna units; Step 2, initialize i=1; Step 3, controlling the selection switch to connect the i-th optional antenna unit to the public down-conversion receiving device; Step 4: a local oscillator signal source generates a local synchronization signal required by the reference down-conversion receiving device and the common down-conversion receiving device; Step 5: The reference down-conversion receiving device mixes the radio frequency signal received by the reference antenna unit with the local synchronization signal, and performs an orthogonal transform to complete the down-conversion process to obtain a first digital sequence of the I / Q combined baseband signal; the public down-conversion receiving device mixes the radio frequency signal received by the optional antenna unit with the local synchronization signal, and performs an orthogonal transform to complete the down-conversion process to obtain a second digital sequence of the I / Q combined baseband signal; Step 6: The positioning device determines the cross-correlation matrix between the i-th optional antenna unit and the reference antenna unit based on the first digital sequence and the second digital sequence when the i-th optional antenna unit is connected, and determines whether i is less than or equal to N. If so, execute i = i + 1 and return to step 3; otherwise, proceed to step 7; where N is the number of optional antenna units; Step 7: The positioning device determines the autocorrelation matrix of the array antenna according to the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected, and locates the OBU based on the autocorrelation matrix.

8. The method according to claim 7, characterized in that The reference down-conversion receiving device and the common down-conversion receiving device obtain the digital sequence in the following manner, including: The radio frequency signal is amplified by a low noise amplifier LAN and then mixed with a local synchronization signal, and after mixing, filtered, amplified, A / D converted, and digitally orthogonally transformed in sequence to obtain a digital in-phase component I and a digital quadrature component Q, so as to obtain a digital sequence of a baseband signal I / Q combined after orthogonal transformation based on the digital in-phase component I and the digital quadrature component Q; or The RF signal is amplified by a low-noise amplifier LAN and then subjected to orthogonal mixing with a local synchronization signal to obtain an analog in-phase component I and an analog quadrature component Q. The analog in-phase component I and the analog quadrature component Q are filtered, amplified, and A / D converted in sequence to obtain a digital in-phase component I and a digital quadrature component Q. A digital sequence of a baseband signal I / Q merged after orthogonal transformation is obtained based on the digital in-phase component I and the digital quadrature component Q.

9. The method according to claim 7, characterized in that The positioning device determines a normalized mutual correlation matrix between the i-th optional antenna unit and the reference antenna unit based on a first digital sequence and a second digital sequence when the i-th optional antenna unit is connected, including: Among them, R′ sn is the normalized cross-correlation matrix of the two channels when the nth optional antenna unit is connected; C n is the normalization coefficient; X s is the first digital sequence, X n is the second digital sequence; is the conjugate of the first number sequence; is the conjugate of the second digital sequence; A n is the amplitude of the optional antenna element No. n; is the phase of the optional antenna unit No. n; A s is the amplitude of the reference antenna unit; the phase of the reference antenna unit is the 0 phase point.

10. The method according to claim 7, characterized in that The positioning device determines the autocorrelation matrix of the array antenna according to the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected, and locates the OBU based on the autocorrelation matrix, including: Determining the autocorrelation matrix of the array antenna according to the normalized cross-correlation matrix of the two channels when each optional antenna unit is connected; Calculate the power spectrum based on the autocorrelation matrix, and select the angle corresponding to the maximum value of the power spectrum as the incident angle θ of the OBU; Positioning the OBU according to the installation information of the roadside unit RSU and the incident angle θ to determine the coordinate information of the OBU; The step of determining the autocorrelation matrix of the array antenna according to the normalized mutual correlation matrix of the two channels when each optional antenna unit is connected includes: Among them, R xx is the autocorrelation matrix; the empty element in the upper triangle of the i-th row and j-th column in the autocorrelation matrix is: The empty element in the jth row and ith column of the lower triangle of the autocorrelation matrix is: * indicates conjugation.

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