Disclosure of Invention
In view of the above problems, the present invention is proposed to provide a beamforming method and a beamforming apparatus for a 3D-MIMO system that overcome the above problems or at least partially solve the above problems, solving the problem of how to apply a fast beamforming technique in a miniaturized single carrier communication device.
According to an aspect of the present invention, there is provided a beamforming method for a 3D-MIMO system for a circular antenna array, comprising the steps of:
acquiring an autocorrelation matrix of a received signal according to the received signals of a plurality of antennas;
respectively and continuously adjusting an initial horizontal angle and an initial vertical angle within a range of 360 degrees according to the preset horizontal angle coarse granularity and the preset vertical angle coarse granularity to carry out omnibearing coarse scanning on the 3D-MIMO system, acquiring received signal power according to the adjusted initial horizontal angle and initial vertical angle, and taking the maximum received signal power as the coarse horizontal angle and the coarse vertical angle, wherein the preset horizontal angle coarse granularity and the preset vertical angle coarse granularity are determined according to the number of antennas of the circular antenna array;
respectively and continuously adjusting a coarse horizontal angle and a coarse vertical angle within a predetermined small angle range according to predetermined horizontal angle fine granularity and vertical angle fine granularity to perform small-angle high-precision scanning on the 3D-MIMO system, acquiring received signal power according to the adjusted coarse horizontal angle and coarse vertical angle, and taking the maximum received signal power within the predetermined small angle range as a fine horizontal angle and a fine vertical angle, wherein the predetermined horizontal angle fine granularity and the predetermined vertical angle fine granularity are determined according to the predetermined angle range;
and acquiring a beam forming factor according to the precise horizontal angle and the precise vertical angle so as to complete beam forming of the 3D-MIMO system.
Further, the preset horizontal angle coarse granularity and the preset vertical angle coarse granularity are determined according to the number of the antennas of the circular antenna array through the following formulas:
part1=360°/N
part2=180°/N
wherein part1 is the predetermined horizontal angle coarse granularity, part2 is the predetermined vertical angle coarse granularity, and N is the number of antennas of the circular antenna array.
Further, the initial horizontal angle and the initial vertical angle are respectively and continuously adjusted within the range of 360 degrees according to the preset horizontal angle coarse granularity and the preset vertical angle coarse granularity, and the method is specifically realized as follows:
the initial horizontal angle is kept unchanged in the horizontal dimension, and the initial vertical angle is sequentially accumulated in the vertical dimension according to the preset coarse granularity of the vertical angle to complete 360-degree scanning;
accumulating the initial horizontal angle once according to the preset vertical angle coarse granularity, keeping the horizontal angle after the accumulation once unchanged on the horizontal dimension, and sequentially accumulating the initial vertical angle on the vertical dimension according to the preset vertical angle coarse granularity to finish 360-degree scanning;
and obtaining a plurality of groups of adjusted initial horizontal angles and initial vertical angles until the accumulation of the initial horizontal angles is finished by 360 degrees.
Further, the predetermined horizontal angle precision and vertical angle precision are determined according to the predetermined angle range, and the following is specifically realized:
determining a horizontal predetermined angular range of [ theta ]
1-Δθ,θ
1+Δθ]Wherein, theta
1Is a coarse horizontal angle, and delta theta is a coarse horizontal angle error; a vertical predetermined angle range of
Wherein,
the angle is a coarse vertical angle, and the angle is a coarse vertical angle,
is a coarse vertical angle error;
the predetermined horizontal angle fine granularity is 2 delta theta/n
1Where Δ θ is the coarse horizontal angle error, n
1Adjusting times for the coarse horizontal angle; a predetermined vertical angle precision of
Wherein,
for coarse vertical angle error, n
2The number of times of coarse vertical angle adjustment is determined.
Further, the coarse horizontal angle and the coarse vertical angle are respectively and continuously adjusted within a predetermined small angle range according to the predetermined horizontal angle precision and the predetermined vertical angle precision, and the method is specifically realized as follows:
the coarse horizontal angle remains constant in the horizontal dimension to
Sequentially accumulating the coarse vertical angles in the vertical dimension by unit, and finishing the angles as
Scanning;
accumulating the coarse horizontal angle once by 2 delta theta/n
1The horizontal angle after one accumulation is kept constant in the horizontal dimension to
Sequentially accumulating the coarse vertical angles in the vertical dimension by unit, and finishing the angles as
Scanning;
and obtaining a plurality of groups of adjusted coarse horizontal angles and coarse vertical angles until the coarse horizontal angles are accumulated to complete 360-degree scanning.
Further, an autocorrelation matrix of the received signal is obtained from the received signals of the plurality of antennas by the following formula:
Ruu=E[U(t)*UH(t)]
wherein R isuuAs an autocorrelation function, E [. cndot.)]For the autocorrelation matrix desired value, U (t) is the received signal matrix, UH(t) is the conjugate matrix of the received signal matrix.
Further, the received signal power is obtained by the following formula:
wherein, P
cbf(theta, phi) is the received signal power,
as a weighting coefficient, R
uuIn order to be a function of the auto-correlation,
is the conjugate of the weighting coefficient.
Further, a beamforming factor is obtained according to the fine horizontal angle and the fine vertical angle by the following formula:
wherein w (theta, phi) is a beam forming factor, R is the radius of the circular antenna array, theta is the horizontal angle of a received signal,
the vertical angle of the received signal is N, N is the number of antennas, N is the total number of antennas of the circular antenna array, and λ is the wavelength of the received signal.
According to another aspect of the present invention, there is provided a beamforming apparatus for a 3D-MIMO system, comprising:
the receiving signal processing module is used for acquiring an autocorrelation matrix of the receiving signals according to the receiving signals of the plurality of antennas;
the system comprises a received signal incidence angle coarse scanning module, a signal receiving module and a signal receiving module, wherein the received signal incidence angle coarse scanning module is used for respectively and continuously adjusting an initial horizontal angle and an initial vertical angle within a range of 360 degrees according to a preset horizontal angle coarse granularity and a preset vertical angle coarse granularity to carry out omnibearing coarse scanning on a 3D-MIMO system, obtaining received signal power according to the adjusted initial horizontal angle and initial vertical angle, and determining the maximum received signal power as a coarse horizontal angle and a coarse vertical angle, wherein the preset horizontal angle coarse granularity and the preset vertical angle coarse granularity are determined according to the number of antennas of a circular antenna array;
the system comprises a receiving signal incidence angle fine scanning module, a signal receiving module and a signal receiving module, wherein the receiving signal incidence angle fine scanning module is used for continuously adjusting a coarse horizontal angle and a coarse vertical angle within a predetermined small angle range according to predetermined horizontal angle fine granularity and vertical angle fine granularity to perform small-angle high-precision scanning on a 3D-MIMO system, acquiring receiving signal power according to the adjusted coarse horizontal angle and coarse vertical angle, and taking the maximum receiving signal power within the predetermined small angle range as a fine horizontal angle and a fine vertical angle, wherein the predetermined horizontal angle fine granularity and the predetermined vertical angle fine granularity are determined according to the predetermined angle range;
and the beam forming module is used for acquiring beam forming factors according to the precise horizontal angle and the precise vertical angle so as to complete beam forming of the 3D-MIMO system.
Further, in the received signal incidence angle coarse scanning module, the predetermined horizontal angle coarse granularity and vertical angle coarse granularity are determined according to the number of antennas of the circular antenna array by the following formulas:
part1=360°/N
part2=180°/N
wherein part1 is the predetermined horizontal angle coarse granularity, part2 is the predetermined vertical angle coarse granularity, and N is the number of antennas of the circular antenna array.
Compared with the prior art, the invention has the following advantages:
1. the beam forming method and the beam forming device of the 3D-MIMO system adopt the circular antenna array of the 3D-MIMO to realize horizontal 360-degree and pitching 360-degree three-dimensional rapid beam scanning, and can meet the communication requirement of the whole spherical surface of the unmanned aerial vehicle at 360 degrees;
2. the beam forming method and the beam forming device of the 3D-MIMO system perform two-stage scanning of coarse scanning and fine scanning on the incident angle of the received signal, so that the acquired incident angle of the received signal is more accurate;
3. the beam forming method and the beam forming device of the 3D-MIMO system respectively refine the horizontal scanning granularity and the vertical scanning granularity of the two-stage scanning, can reduce the workload of beam scanning, improve the speed of beam scanning and greatly save the time of beam scanning.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The method and the device are mainly used for solving the problem of how to apply the rapid beam forming technology to communication equipment of a miniaturized single carrier, and particularly, the method and the device provided by the invention need to be capable of meeting the communication requirement of the whole spherical surface of 360 degrees of an unmanned aerial vehicle, so that the method and the device adopt the circular antenna array of the 3D-MIMO shown in FIG. 1 to realize three-dimensional rapid beam scanning of 360 degrees in horizontal and 360 degrees in pitching. In the figure, the direction s is the direction of the received signal, theta is the vertical angle of the received signal,
is the horizontal angle of the received signal.
Taking the center of the circle in fig. 1 as the phase reference point, the phase difference between the nth antenna and the center of the circle can be obtained as
The normalized directional pattern function of the circular array is therefore
When theta is equal to theta
0,
When the temperature of the water is higher than the set temperature,
taking the maximum value.
Direction steering vector to beam former of circular antenna array
Is composed of
The method for calculating the beam weight is a mathematical method for calculating the optimal weight by synthesizing all input information according to a certain criterion. The most important and most common of these criteria include the minimum mean square error criterion (MMSE), the maximum signal-to-noise ratio criterion (MSNR), and the linearly constrained minimum variance criterion (LCMV). Although the three criteria are completely different in principle, in an ideal case, the three criteria are theoretically equivalent, and the obtained optimal weight vectors can be expressed as wiener solutions, namely, the optimal weight is
When the antenna elements have the same characteristics and are all omnidirectional antennas, the matrix R is a diagonal matrix, and the element values on the diagonal are the same.
s (t) is the original transmitted signal, the received signal of the antenna is u
The received signal u uses a Vector Channel Impulse Response (VCIR):
where I is the total number of multipaths, θ
iIs the direction of the i-way multipath,
α
i,τ
irespectively, the direction vector, magnitude and time delay of the received signal. The vector channel impulse response gives the impulse response from transmit to receive (including the antenna array). It is the total response of the propagation space and manifold.
If the transmission signal is s (t), the receiving signal is:
where I is the total number of multipaths, θ
iIs the direction of the i-way multipath,
α
i,τ
irespectively, the direction vector, magnitude and time delay of the received signal.
The basic principle of the method of the invention is as follows: by scanning the angle theta in two dimensions,
the method obtains the incoming wave direction of the signal, thereby completing the beam forming. I.e. continuously varying W
That is to say, the angle theta is constantly changed,
two variables, one being the pitch angle and one being the level angle, when
When the angle of the variation is the same as or close to the angle of the input signal, the output power P is the maximum, and the output power is at this time
Fig. 2 is a diagram of steps of a beamforming method of a 3D-MIMO system according to the present invention, and referring to fig. 2, the beamforming method of the 3D-MIMO system according to the present invention is applied to a circular antenna array, and includes the following steps:
s1, obtaining an autocorrelation matrix of the received signals according to the received signals of the multiple antennas;
specifically, an autocorrelation matrix of the received signal is obtained from the received signals of the plurality of antennas by the following formula:
wherein R is
uuIn order to be a function of the auto-correlation,
in order to receive the vector of signals,
for the conjugate of the received signal vector, E [. cndot]For the autocorrelation matrix desired value, U (t) is the received signal matrix, U
H(t) is the conjugate matrix of the received signal matrix.
For example, U is a received signal of N-8 antennas, and each antenna receives symbol data of L-128 symbols as acquired physical layer data. Therefore, U (t) is a matrix of N L, UHAnd (t) multiplying the two matrixes of L and N to obtain an autocorrelation matrix of N and N.
S2, respectively and continuously adjusting an initial horizontal angle and an initial vertical angle within a range of 360 degrees according to the preset horizontal angle coarse granularity and the preset vertical angle coarse granularity to carry out omnibearing coarse scanning on the 3D-MIMO system, acquiring received signal power according to the adjusted initial horizontal angle and initial vertical angle, and taking the maximum received signal power as a coarse horizontal angle and a coarse vertical angle, wherein the preset horizontal angle coarse granularity and the preset vertical angle coarse granularity are determined according to the number of antennas of the circular antenna array;
specifically, the received signal power is obtained by the following formula:
wherein, P
cbf(theta, phi) is the received signal power,
as a weighting coefficient, R
uuIn order to be a function of the auto-correlation,
is the conjugate of the weighting coefficient.
The derivation of the formula for obtaining the received signal power is as follows:
to obtain main lobe directional alignment
The beam of (2), the signal actually received by the multiple antennas of the drone is a signal from a well-defined direction as follows
Wherein s (t) is the original transmitting signal, and the receiving signal of the antenna is
The spatial matching weight W for this direction can be expressed as
The aim of the invention is to maximize the mean square power of the signal Z after the weighting is completed, if Z is the maximum mean square power, it means that the incoming wave direction is found by adjusting the weighting coefficient W
That is, let P
cbfThe power is maximum, so the output power of this conventional beamformer can be expressed as:
wherein Ruu is the autocorrelation function (covariance matrix) of the received signal of the array,
σs=E[s(t)2]
σn=E[n(t)2]
specifically, the predetermined horizontal angle coarse granularity and the predetermined vertical angle coarse granularity are determined according to the number of antennas of the circular antenna array by the following formulas:
part1=360°/N
part2=180°/N
wherein part1 is the predetermined horizontal angle coarse granularity, part2 is the predetermined vertical angle coarse granularity, and N is the number of antennas of the circular antenna array.
Specifically, the initial horizontal angle and the initial vertical angle are respectively and continuously adjusted within a range of 360 degrees according to the preset horizontal angle coarse granularity and the preset vertical angle coarse granularity, and the method is specifically realized as follows:
the initial horizontal angle is kept unchanged in the horizontal dimension, and the initial vertical angle is sequentially accumulated in the vertical dimension according to the preset coarse granularity of the vertical angle to complete 360-degree scanning;
accumulating the initial horizontal angle once according to the preset vertical angle coarse granularity, keeping the horizontal angle after the accumulation once unchanged on the horizontal dimension, and sequentially accumulating the initial vertical angle on the vertical dimension according to the preset vertical angle coarse granularity to finish 360-degree scanning;
and obtaining a plurality of groups of adjusted initial horizontal angles and initial vertical angles until the accumulation of the initial horizontal angles is finished by 360 degrees.
Respectively substituting the initial horizontal angles and the initial vertical angles into a formula
In (1) obtaining
Then theta
1The angle is a coarse horizontal angle, and the angle is a coarse horizontal angle,
is a coarse vertical angle.
More specifically, θ is from [ -180 °, 180 ° according to the angle of part1 [ -360/N [ -180 ° ]]The data are accumulated in sequence and then are added,
from-180 DEG, 180 DEG according to the
angle 180 DEG/N of part2]And sequentially accumulating to realize large-scale full-angle scanning of horizontal dimension and vertical dimension. For example, when N is 8, the initial horizontal angle is 0 ° and the initial vertical angle is 0 °, the coarse scanning process is: keeping the initial horizontal angle at 0 degree, adjusting the initial vertical angle at 0 degree, 22.5 degree, 45 degree, 67.5 degree, 90 degree, 112.5 degree, 135 degree, 157.5 degree, 180 degree, 22.5 degree, 45 degree, 67.5 degree, 90 degree, 112.5 degree, 135 degree, 157.5 degree and 180 degree; the initial horizontal angle is adjusted to be 45 degrees, the initial vertical angle is adjusted to be 0 degrees, 22.5 degrees, 45 degrees, 67.5 degrees, 90 degrees, 112.5 degrees and 135 degrees respectively157.5 degrees, -180 degrees, -22.5 degrees, -45 degrees, -67.5 degrees, -90 degrees, -112.5 degrees, -135 degrees, -157.5 degrees, 180 degrees; and by analogy, respectively adjusting the initial horizontal angles to be 90 degrees, 135 degrees, 180 degrees, -45 degrees, -90 degrees, -135 degrees and-180 degrees, and acquiring the adjusted initial vertical angles under different adjusted initial horizontal angles.
S3, continuously adjusting a coarse horizontal angle and a coarse vertical angle within a predetermined small angle range according to predetermined horizontal angle precision and vertical angle precision to perform small-angle high-precision scanning on the 3D-MIMO system, acquiring received signal power according to the adjusted coarse horizontal angle and coarse vertical angle, and taking the maximum received signal power within the predetermined small angle range as a fine horizontal angle and a fine vertical angle, wherein the predetermined horizontal angle precision and the predetermined vertical angle precision are determined according to the predetermined angle range;
specifically, the predetermined horizontal angle precision and the predetermined vertical angle precision are determined according to the predetermined angle range, and the following is specifically realized:
determining a horizontal predetermined angular range of [ theta ]
1-Δθ,θ
1+Δθ]Wherein, theta
1Is a coarse horizontal angle, and delta theta is a coarse horizontal angle error; a vertical predetermined angle range of
Wherein,
the angle is a coarse vertical angle, and the angle is a coarse vertical angle,
is a coarse vertical angle error;
the predetermined horizontal angle fine granularity is 2 delta theta/n
1Where Δ θ is the coarse horizontal angle error, n
1Adjusting times for the coarse horizontal angle; a predetermined vertical angle precision of
Wherein,
for coarse vertical angle error, n
2The number of times of coarse vertical angle adjustment is determined.
Specifically, the coarse horizontal angle and the coarse vertical angle are respectively and continuously adjusted within a predetermined small angle range according to the predetermined horizontal angle precision and the predetermined vertical angle precision, and the method is specifically realized as follows:
the coarse horizontal angle remains constant in the horizontal dimension to
Sequentially accumulating the coarse vertical angles in the vertical dimension by unit, and finishing the angles as
Scanning;
accumulating the coarse horizontal angle once by 2 delta theta/n
1The horizontal angle after one accumulation is kept constant in the horizontal dimension to
Sequentially accumulating the coarse vertical angles in the vertical dimension by unit, and finishing the angles as
Scanning;
and obtaining a plurality of groups of adjusted coarse horizontal angles and coarse vertical angles until the coarse horizontal angles are accumulated to complete 360-degree scanning.
For example, when Δ θ is 3 °, n
1When the granularity is 10 times, the preset horizontal angle fine granularity is 0.6 degrees; when in use
Is 3 DEG, n
2At 10 times, the predetermined vertical angle fine particle size was 0.6 °.
Respectively substituting the multiple groups of adjusted rough horizontal angles and rough vertical angles into a formula
In (1) obtaining
Then theta
2The angle of the horizontal line is accurate,
is a precise vertical angle.
And S4, acquiring a beam forming factor according to the precise horizontal angle and the precise vertical angle so as to complete beam forming of the 3D-MIMO system.
Specifically, the beamforming factor is obtained according to the fine horizontal angle and the fine vertical angle by the following formula:
wherein w (theta, phi) is a beam forming factor, R is the radius of the circular antenna array, and theta
2The angle of the horizontal line is accurate,
the angle is a precise vertical angle, N is the number of antennas, N is the total number of antennas of the circular antenna array, and λ is the wavelength of the received signal.
The beam forming method of the 3D-MIMO system adopts the circular antenna array of the 3D-MIMO to realize horizontal 360-degree and pitching 360-degree three-dimensional rapid beam scanning, and can meet the communication requirement of the whole spherical surface of 360 degrees of the unmanned aerial vehicle.
The beam forming method of the 3D-MIMO system performs two-stage scanning of coarse scanning and fine scanning on the incident angle of the received signal, and the acquired incident angle of the received signal is more accurate.
The beam forming method of the 3D-MIMO system respectively refines the horizontal scanning granularity and the vertical scanning granularity of two-stage scanning, can reduce the workload of beam scanning, simultaneously improves the speed of beam scanning, and greatly saves the time of beam scanning. For example, in the prior art, if both level and pitch are one degree scans in terms of 360 degree granularity, NALL 360 x 129600 scan times are required. With the invention, for example, 8 antennas, coarse scanning 8 × 16 times, and accurate scanning: 10 x 10, only NTWO 228 scans are needed in total, which is only 500 times of a full scan, which greatly saves the time of beam scanning, making the angular scanning of 2D-MIMO a solution that can be realized by the product.
For simplicity of explanation, the method embodiments are described as a series of acts or combinations, but those skilled in the art will appreciate that the embodiments are not limited by the order of acts described, as some steps may occur in other orders or concurrently with other steps in accordance with the embodiments of the invention. Further, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred and that no particular act is required to implement the invention.
Fig. 3 is a flowchart of a specific implementation of a beamforming method of a 3D-MIMO system according to the present invention, and referring to fig. 3, the specific implementation of the method according to the present invention includes: receiving uplink channel data u (t) (a) (t) s (t) by the unmanned aerial vehicle; forming an autocorrelation matrix Ruu from the received signals, Ruu being the autocorrelation function (covariance matrix) of the array received signals; according to the number N of the antennas of the circular array, determining the horizontal angle granularity and the vertical angle granularity of the first-stage coarse scanning, and starting the omnibearing first-stage scanning of the 3D-MIMO; according to the following formula
![Figure GDA0002888062550000161](https://patentimages.storage.***apis.com/10/4e/c5/ff9c94d608b55d/GDA0002888062550000161.png)
The large granularity continuously adjusts the horizontal angle and the vertical angle, the maximum power value is searched, and the angle corresponding to the maximum power value is the angle of the opposite userApproximate incoming wave directions, i.e., a coarse horizontal angle and a coarse vertical angle; according to the rough horizontal angle and the rough vertical angle found by the first-stage scanning, second-stage high-precision scanning is carried out near the two angles, the maximum power value is found, the angle corresponding to the maximum power value is the found accurate angle, namely the accurate direction of the incoming wave of the user, the incoming wave direction of the user can be quickly positioned by finding the angles at two stages, so that the scanning of the 3D-MIMO signal angle is quickly completed, the weighting factor of the user is finally determined, and the beam forming and the direction determination of the unmanned aerial vehicle can be quickly completed by the method.
Fig. 4 is a block diagram of a beamforming system of a 3D-MIMO system of the present invention, and referring to fig. 4, a beamforming apparatus of a 3D-MIMO system provided by the present invention includes:
the receiving signal processing module is used for acquiring an autocorrelation matrix of the receiving signals according to the receiving signals of the plurality of antennas;
the system comprises a received signal incidence angle coarse scanning module, a signal receiving module and a signal receiving module, wherein the received signal incidence angle coarse scanning module is used for respectively and continuously adjusting an initial horizontal angle and an initial vertical angle within a range of 360 degrees according to a preset horizontal angle coarse granularity and a preset vertical angle coarse granularity to carry out omnibearing coarse scanning on a 3D-MIMO system, obtaining received signal power according to the adjusted initial horizontal angle and initial vertical angle, and determining the maximum received signal power as a coarse horizontal angle and a coarse vertical angle, wherein the preset horizontal angle coarse granularity and the preset vertical angle coarse granularity are determined according to the number of antennas of a circular antenna array;
the system comprises a receiving signal incidence angle fine scanning module, a signal receiving module and a signal receiving module, wherein the receiving signal incidence angle fine scanning module is used for continuously adjusting a coarse horizontal angle and a coarse vertical angle within a predetermined small angle range according to predetermined horizontal angle fine granularity and vertical angle fine granularity to perform small-angle high-precision scanning on a 3D-MIMO system, acquiring receiving signal power according to the adjusted coarse horizontal angle and coarse vertical angle, and taking the maximum receiving signal power within the predetermined small angle range as a fine horizontal angle and a fine vertical angle, wherein the predetermined horizontal angle fine granularity and the predetermined vertical angle fine granularity are determined according to the predetermined angle range;
and the beam forming module is used for acquiring beam forming factors according to the precise horizontal angle and the precise vertical angle so as to complete beam forming of the 3D-MIMO system.
For the device embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, refer to the partial description of the method embodiment.
The beam forming device of the 3D-MIMO system adopts the circular antenna array of the 3D-MIMO to realize horizontal 360-degree and pitching 360-degree three-dimensional rapid beam scanning, and can meet the communication requirement of the whole spherical surface of 360 degrees of the unmanned aerial vehicle.
Further, in the received signal incidence angle coarse scanning module, the predetermined horizontal angle coarse granularity and vertical angle coarse granularity are determined according to the number of antennas of the circular antenna array by the following formulas:
part1=360°/N
part2=180°/N
wherein part1 is the predetermined horizontal angle coarse granularity, part2 is the predetermined vertical angle coarse granularity, and N is the number of antennas of the circular antenna array.
The invention simulates two-stage 3D-NINO beam scanning:
simulation of theta in 8-antenna circular array
2=30°,
The beam in time, see fig. 5, actually comes out 4 directional signals due to the mapping of the quadrants, and the beamforming factors are the same, in this case, in the known beam DOA diagram, X is 31, Y is 60, and Z is 7.993. Wherein the horizontal direction beam scanning is performed at 60 DEG in the horizontal directionAs shown in fig. 6, the vertical beam scanning pattern at a vertical direction of 30 ° is shown in fig. 7.
Coarse scanning: a 3D-MIMO beam scan pattern of a 30 ° coarse scan of an 8-antenna circular array was simulated, and as a result, as shown in fig. 8, in the DOA pattern of the beams obtained by the method and apparatus of the present invention, X is 30, Y is 60, and Z is 7.488, which are closer to known beams. Wherein, the schematic diagram of coarse scanning with 30 ° granularity in the horizontal direction is shown in fig. 9, and the schematic diagram of coarse scanning with 30 ° granularity in the vertical direction is shown in fig. 10.
Fine scanning: a 3D-MIMO beam scan pattern with a 3 ° granularity fine scan of an 8-antenna circular array was simulated, and the result is shown in fig. 11. Fig. 12 shows a schematic diagram of coarse scanning with a granularity of 3 ° in the horizontal direction, and fig. 13 shows a schematic diagram of coarse scanning with a granularity of 3 ° in the vertical direction.
Certain error exists in the actual angle testing process, the angle error is generally controlled within 3 degrees, and the signal loss is less than 0.3 dB. This is because the number of antennas is small, the angle is not very sharp, and the performance is less affected by the angle difference. Therefore, the beamforming algorithm at this time is less affected by noise. The invention simulates a beam contrast diagram with an angle error of 3 degrees, and referring to fig. 14 and 15, the two directional diagrams are almost coincident.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.