Beamforming method and system for train-ground communication of super-high-speed maglev train

Abstract

The present application relates to the technical field of wireless communication, and especially relates to a kind of super high-speed maglev train ground communication beam forming method and system, wherein the method comprises: ground induction loop positioning device sends first train position information to ground base station in real time, vehicle-mounted laser coding positioning device sends second train position information to vehicle-mounted terminal in real time, the ground base station and the vehicle-mounted terminal are configured with antenna array for simulating beam forming structure, the antenna in antenna array is millimeter wave array antenna, the number of antennas in the antenna array of the ground base station is equal to the number of antennas in the antenna array of the vehicle-mounted terminal;The ground base station calculates first beam pointing angle according to first train position information, and the vehicle-mounted terminal calculates second beam pointing angle according to second train position information;According to the first beam pointing angle and the second beam pointing angle, the antenna in the antenna array of the ground base station and the antenna in the antenna array of the vehicle-mounted terminal are subjected to joint beam forming.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to a super-high-speed maglev train train-ground communication beamforming method and system. BACKGROUND

[0002] High-speed flying trains use magnetic suspension to reduce frictional resistance, and the design speed can reach 1000 km / h. In order to reduce air resistance, it runs in a low-vacuum tube. The maintenance of the low-vacuum environment requires the use of metal as the material of the tube.

[0003] Compared with existing rail transit and high-speed rail, the environment of a low-vacuum sealed metal tube is similar to that of a tunnel, but there are still differences, which are embodied in the electromagnetic wave propagation characteristics. Most tunnels are built of concrete, which can absorb electromagnetic wave signals to a large extent, but metal tubes almost reflect electromagnetic wave signals without attenuation. For a high-speed train-ground communication system, this will bring significant multipath effects, which will adversely affect the recovery of the original signal at the receiving end and will also deteriorate the performance of the communication system (bit error rate, transmission rate).

[0004] The above-mentioned multipath effect refers to the fact that after electromagnetic waves propagate through different paths, the components arrive at the receiving end at different times and are superimposed on each other according to their respective phases, causing interference. When the maximum delay spread of multipath transmission is greater than the symbol width, inter-symbol interference occurs, causing the original signal to be distorted or errors to occur, resulting in a decrease in communication quality. For example, electromagnetic waves propagate along two different paths, and the lengths of the two paths differ by exactly half a wavelength. Then the two signals arrive at the terminal at exactly the same time (the wave peak coincides with the wave trough).

[0005] In the rail transit 4G LTE-M system, the orthogonal frequency division multiplexing (OFDM) technology is used to cope with the multipath effect. By increasing the cyclic prefix (CP, which is equivalent to the guard interval GI between adjacent symbols), the multipath delay can be countered. As long as the CP length is greater than the maximum multipath delay, the inter-symbol interference caused can be basically eliminated.

[0006] OFDM belongs to a narrowband communication system. In addition, for a wideband single-carrier communication system, the receiving end performs channel equalization processing. The mechanism is to compensate for the characteristics of the channel or the entire transmission system. According to the constant or variable characteristics of the channel, it is divided into two categories: linear equalization and nonlinear equalization, which are realized by designing filters. The main purpose is to eliminate or weaken the inter-symbol interference of wideband communication.

[0007] In OFDM technology, if the time delay of a certain multipath is greater than the CP length, the previous OFDM symbol will leak into the current OFDM symbol sequence through the path, causing inter-symbol interference. To avoid this, a longer CP is needed, but because the CP occupies part of the OFDM symbol, this will cause a large overhead, reducing the effective data transmission capacity of the system. That is, the length of the CP cannot be increased indefinitely. OFDM technology aims to achieve higher spectral efficiency within a limited spectrum, and if the CP occupies too much resource, it violates the original design intention of OFDM.

[0008] In addition, because the subcarrier width of OFDM is 15 kHz, it is very sensitive to Doppler shift. At a speed of 1000 km / h, the Doppler shift value when using a 450 MHz frequency band is 416.67 Hz, which is 2.7% of the subcarrier width; the Doppler shift value when using a 1.8 GHz frequency band is 1.67 kHz, which is 10.8% of the subcarrier width. Generally, when the frequency shift value exceeds 2% of the carrier bandwidth, it will have a relatively adverse impact on the communication system and will cause OFDM subcarrier interference. Therefore, the existing OFDM technology is not suitable for application in a super high-speed mobile scenario (i.e., is not suitable for super high-speed maglev trains). SUMMARY

[0009] The application provides a super high-speed maglev train train-ground communication beamforming method and system, which can solve the technical problems in the prior art.

[0010] The application provides a super high-speed maglev train train-ground communication beamforming method, which comprises the following steps:

[0011] The ground induction loop positioning device sends first train position information to a ground base station in real time, and a vehicle-mounted laser coding positioning device sends second train position information to a vehicle-mounted terminal in real time, the ground base station and the vehicle-mounted terminal are provided with an antenna array for simulating a beamforming structure, the antennas in the antenna array are millimeter wave array antennas, and the number of antennas in the antenna array of the ground base station is equal to the number of antennas in the antenna array of the vehicle-mounted terminal.

[0012] The ground base station calculates a first beam pointing angle according to the first train position information, and the vehicle-mounted terminal calculates a second beam pointing angle according to the second train position information.

[0013] The antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle-mounted terminal are subjected to joint beamforming according to the first beam pointing angle and the second beam pointing angle.

[0014] Preferably, the ground base station calculates a first beam pointing angle according to the first train position information, and the vehicle-mounted terminal calculates a second beam pointing angle according to the second train position information.

[0015] determining a first train two-dimensional coordinate of the train in a predetermined angle coordinate system and a first base station two-dimensional coordinate of the ground base station in the predetermined angle coordinate system according to the first train position information, the first train two-dimensional coordinate comprising a first train horizontal coordinate and a first train vertical coordinate, the first base station two-dimensional coordinate comprising a first base station horizontal coordinate and a first base station vertical coordinate,

[0016] calculating a first beam pointing angle according to the first train two-dimensional coordinate and the first base station two-dimensional coordinate;

[0017] calculating a second beam pointing angle according to second train position information by the vehicle terminal comprises:

[0018] determining a second train two-dimensional coordinate of the train in a predetermined angle coordinate system and a second base station two-dimensional coordinate of the ground base station in the predetermined angle coordinate system according to the second train position information, the second train two-dimensional coordinate comprising a second train horizontal coordinate and a second train vertical coordinate, the second base station two-dimensional coordinate comprising a second base station horizontal coordinate and a second base station vertical coordinate,

[0019] calculating a second beam pointing angle according to the second train two-dimensional coordinate and the second base station two-dimensional coordinate.

[0020] Preferably, the first beam pointing angle or the second beam pointing angle is calculated by the following formula:

[0021]

[0022] wherein θ is the first beam pointing angle or the second beam pointing angle, x1 is the first train horizontal coordinate or the second train horizontal coordinate, the first train vertical coordinate or the second train vertical coordinate is 0, x2 is the first base station horizontal coordinate or the second base station horizontal coordinate, and h is the first base station vertical coordinate or the second base station vertical coordinate.

[0023] Preferably, jointly beamforming the antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle terminal according to the first beam pointing angle and the second beam pointing angle comprises:

[0024] obtaining a normalized pointing vector according to the first beam pointing angle and the second beam pointing angle;

[0025] determining a beamforming vector according to the normalized pointing vector;

[0026] jointly beamforming the antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle terminal according to the beamforming vector.

[0027] Preferably, in the case that only one train is running within the coverage range of a single ground base station, the beamforming vector is equal to the normalized pointing vector, and the beamforming vector is represented by the following formula:

[0028]

[0029] wherein w(N, θ) is a beamforming vector, and N is the number of antennas in the antenna array of the ground base station or the number of antennas in the antenna array of the vehicle terminal.

[0030] The application also provides a super-high-speed maglev train vehicle-ground communication beamforming system, wherein the system comprises:

[0031] A ground induction loop positioning device for transmitting first train position information to the ground base station in real time.

[0032] A vehicle-mounted laser coding positioning device for transmitting second train position information to the vehicle terminal in real time.

[0033] A ground base station for calculating a first beam pointing angle according to the first train position information.

[0034] A vehicle terminal for calculating a second beam pointing angle according to the second train position information, wherein the ground base station and the vehicle terminal are configured with an antenna array for simulating a beamforming structure, the antennas in the antenna array are millimeter wave array antennas, the number of antennas in the antenna array of the ground base station is equal to the number of antennas in the antenna array of the vehicle terminal.

[0035] A beamforming device for jointly beamforming the antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle terminal according to the first beam pointing angle and the second beam pointing angle.

[0036] Preferably, the ground base station calculates the first beam pointing angle according to the first train position information, which comprises:

[0037] determining a first train two-dimensional coordinate of the train in a predetermined angle coordinate system and a first base station two-dimensional coordinate of the ground base station in the predetermined angle coordinate system according to the first train position information, wherein the first train two-dimensional coordinate comprises a first train horizontal coordinate and a first train vertical coordinate, and the first base station two-dimensional coordinate comprises a first base station horizontal coordinate and a first base station vertical coordinate,

[0038] calculating the first beam pointing angle according to the first train two-dimensional coordinate and the first base station two-dimensional coordinate.

[0039] The vehicle terminal calculates the second beam pointing angle according to the second train position information, which comprises:

[0040] determining a second train two-dimensional coordinate of the train and a second base station two-dimensional coordinate of the ground base station in a predetermined angle coordinate system according to the second train position information, the second train two-dimensional coordinate comprising a second train horizontal coordinate and a second train vertical coordinate, the second base station two-dimensional coordinate comprising a second base station horizontal coordinate and a second base station vertical coordinate,

[0041] calculating a second beam pointing angle according to the second train two-dimensional coordinate and the second base station two-dimensional coordinate.

[0042] Preferably, the first beam pointing angle or the second beam pointing angle is calculated by the following formula:

[0043]

[0044] wherein θ is the first beam pointing angle or the second beam pointing angle, x1 is the first train horizontal coordinate or the second train horizontal coordinate, the first train vertical coordinate or the second train vertical coordinate is 0, x2 is the first base station horizontal coordinate or the second base station horizontal coordinate, and h is the first base station vertical coordinate or the second base station vertical coordinate.

[0045] Preferably, the beamforming device jointly beamforms the antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle-mounted terminal according to the first beam pointing angle and the second beam pointing angle comprises:

[0046] obtaining a normalized pointing vector according to the first beam pointing angle and the second beam pointing angle;

[0047] determining a beamforming vector according to the normalized pointing vector;

[0048] jointly beamforming the antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle-mounted terminal according to the beamforming vector.

[0049] Preferably, in the case that only one train is running within the coverage range of a single ground base station, the beamforming vector is equal to the normalized pointing vector, and the beamforming vector is represented by the following formula:

[0050]

[0051] wherein w(N, θ) is the beamforming vector, and N is the number of antennas in the antenna array of the ground base station or the number of antennas in the antenna array of the vehicle-mounted terminal.

[0052] Through the technical solution, in the running process of the train, each positioning device constantly provides position information to the ground base station and the vehicle terminal in the train-ground communication system in real time, the ground base station and the vehicle terminal correspondingly also constantly calculate the corresponding beam pointing angle and perform beamforming on the array antenna according to the beam pointing angle, to realize real-time tracking. By using the millimeter wave array antenna at both ends of the transceiver, the beamforming is performed on the direct direction through the beam pointing angle calculated in real time, to form a very high array gain, to reduce the array gain of the non-direct direction to the greatest extent, to reduce the number of reflection paths, and to reduce the complexity of the channel equalization at the receiving end. BRIEF DESCRIPTION OF DRAWINGS

[0053] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. It is apparent that the accompanying drawings are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0054] Figure 1 A flow chart of a super-high-speed maglev train train-ground communication beamforming method according to an embodiment of the application is shown;

[0055] Figure 2 A schematic diagram of a super-high-speed maglev train train-ground communication beamforming system according to an embodiment of the application is shown;

[0056] Figure 3 A beam gain schematic diagram according to an embodiment of the application is shown. DETAILED DESCRIPTION

[0057] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0058] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" 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, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0059] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples are not intended to limit the scope of the application unless otherwise specifically stated. It is to be understood that the drawings are not necessarily to scale as the dimensions of the parts shown are for the purpose of illustration and description only and not to limit the scope of the application. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail but are intended to be understood as a part of the specification when appropriate. In all examples shown and discussed herein, any specific values are to be interpreted as illustrative only and not as a limitation. Thus, other examples of example embodiments can have different values. It is noted that like numbers and letters on the figures identify like parts throughout the several views, and thus, once an item is defined in one figure, it is not necessary to discuss it further in connection with other figures.

[0060] Figure 1 A flow chart of a method for beamforming of train-ground communication of a maglev train is shown according to an embodiment of the application.

[0061] As shown in Figure 1 An embodiment of the application provides a method for beamforming of train-ground communication of a maglev train, wherein the method comprises:

[0062] S100, a ground induction loop positioning device sends first train position information to a ground base station in real time, and a vehicle-mounted laser coding positioning device sends second train position information to a vehicle-mounted terminal in real time, the ground base station and the vehicle-mounted terminal are configured with an antenna array for simulating a beamforming structure, the antennas in the antenna array are millimeter wave array antennas, and the number of antennas in the antenna array of the ground base station is equal to the number of antennas in the antenna array of the vehicle-mounted terminal;

[0063] S102, the ground base station calculates a first beam pointing angle according to the first train position information, and the vehicle-mounted terminal calculates a second beam pointing angle according to the second train position information;

[0064] Wherein, the beam pointing angle is defined as the cosine value of the linear value of the angle.

[0065] S104, jointly beamforming the antennas in the ground base station antenna array and the antennas in the vehicle terminal antenna array according to the first beam pointing angle and the second beam pointing angle.

[0066] By the above technical solution, in the process of train running, each positioning device provides position information to the ground base station and the vehicle terminal in the train-ground communication system in real time, and the ground base station and the vehicle terminal correspondingly calculate the corresponding beam pointing angle and perform beamforming on the array antenna according to the beam pointing angle, so that real-time tracking is realized. By using the millimeter wave array antenna at both the transmitting end and the receiving end, the beamforming is performed in the direct direction based on the real-time calculated beam pointing angle to form a very high array gain, the array gain in the non-direct direction is reduced to the maximum extent, the number of reflection paths is reduced, and the complexity of channel equalization at the receiving end is reduced. That is, the joint beamforming technology at both the transmitting end and the receiving end can be used to weaken the multipath effect and reduce the number of multipaths.

[0067] In addition, there is a deep fading area directly below the traditional base station antenna, but the millimeter wave array antenna used in the present application does not have the risk of deep fading. When the train runs directly below the base station antenna, the beam pointing angle θ = 0, and the beamforming can still be performed to align the array gains at both the transmitting end and the receiving end.

[0068] In the present application, for each antenna array, one radio frequency chain, N antennas and N phase shifters are included; all antennas are connected to the radio frequency chain, each antenna branch is connected to a phase shifter and a power amplifier, and each phase shifter has a constant modulus.

[0069] For example, the antenna array can be a uniform linear array (ULA), and the number of antennas is N, which is consistent with the number of phase shifters. For the array antenna of the vehicle terminal (vehicle array antenna) side, the running positive direction is defined as 180°, and the running negative direction is defined as 0°; for the array antenna of the ground base station (base station array antenna) side, the running positive direction is defined as 0°, and the running negative direction is defined as 180°, as shown in FIG. 1. Figure 2

[0070] According to an embodiment of the present application, the ground base station calculates the first beam pointing angle according to the first train position information, which includes:

[0071] According to the first train position information, the first train two-dimensional coordinate of the train in a predetermined angle coordinate system and the first base station two-dimensional coordinate of the ground base station in the predetermined angle coordinate system are determined, the first train two-dimensional coordinate includes a first train horizontal coordinate and a first train vertical coordinate, and the first base station two-dimensional coordinate includes a first base station horizontal coordinate and a first base station vertical coordinate,

[0072] The first beam pointing angle is calculated according to the first train two-dimensional coordinate and the first base station two-dimensional coordinate; ​

[0073] The vehicle terminal calculates a second beam pointing angle according to second train position information, and the second beam pointing angle comprises:

[0074] According to the second train position information, a second train two-dimensional coordinate of the train in a predetermined angle coordinate system and a second base station two-dimensional coordinate of the ground base station in the predetermined angle coordinate system are determined, the second train two-dimensional coordinate comprises a second train horizontal coordinate and a second train vertical coordinate, and the second base station two-dimensional coordinate comprises a second base station horizontal coordinate and a second base station vertical coordinate,

[0075] The second beam pointing angle is calculated according to the second train two-dimensional coordinate and the second base station two-dimensional coordinate.

[0076] The predetermined angle coordinate system can be set according to actual conditions, and the present application does not limit this.

[0077] According to an embodiment of the present application, the first beam pointing angle or the second beam pointing angle is calculated by the following formula:

[0078]

[0079] Wherein, θ is the first beam pointing angle or the second beam pointing angle, x1 is the first train horizontal coordinate or the second train horizontal coordinate, the first train vertical coordinate or the second train vertical coordinate is 0, x2 is the first base station horizontal coordinate or the second base station horizontal coordinate, and h is the first base station vertical coordinate or the second base station vertical coordinate.

[0080] That is, the first base station two-dimensional coordinate or the second base station two-dimensional coordinate can be represented as (x2, h), and the first train two-dimensional coordinate or the second train two-dimensional coordinate can be represented as (x1, 0).

[0081] In an ideal state, the position information output by the ground positioning device and the vehicle positioning device is consistent, so the first beam pointing angle and the second beam pointing angle calculated by the ground base station and the vehicle terminal respectively are equal in the ideal state.

[0082] In the present application, the array antenna does not generate gain on the back of the radiation surface, so θ ∈ (-1, 1) (the range corresponds to the angle linear value (0°, 180°) one by one).

[0083] According to an embodiment of the present application, the antennas in the ground base station antenna array and the antennas in the vehicle terminal antenna array are jointly beamformed according to the first beam pointing angle and the second beam pointing angle, and the joint beamforming comprises:

[0084] A normalized pointing vector is obtained according to the first beam pointing angle and the second beam pointing angle;

[0085] A beamforming vector is determined according to the normalized pointing vector.

[0086] The antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle-mounted terminal are jointly beamformed according to the beamforming vector.

[0087] For example, the normalized pointing vector is as shown in the following formula:

[0088]

[0089] By performing normalization, the pointing vector is averaged on each antenna, and the gain is not affected by the number of antennas when calculating the gain.

[0090] According to an embodiment of the present application, in the case where only one train runs in the coverage range of a single ground base station (i.e., only one user), the beamforming vector is equal to the normalized pointing vector, and the beamforming vector is represented by the following formula:

[0091]

[0092] wherein w(N, θ) is the beamforming vector, and N is the number of antennas in the antenna array of the ground base station or the number of antennas in the antenna array of the vehicle-mounted terminal.

[0093] In the present application, each element of the beamforming vector corresponds to a phase shifter.

[0094] Figure 2 A schematic diagram of a beamforming system for train-ground communication of a super-high-speed maglev train according to an embodiment of the present application is shown.

[0095] As shown in Figure 2 The present application provides a beamforming system for train-ground communication of a super-high-speed maglev train, wherein the system comprises:

[0096] A ground induction loop positioning device 10 is configured to transmit first train position information to a ground base station 12 in real time.

[0097] A vehicle-mounted laser coding positioning device 14 is configured to transmit second train position information to a vehicle-mounted terminal 16 in real time.

[0098] The ground base station 12 is configured to calculate a first beam pointing angle according to the first train position information.

[0099] The vehicle-mounted terminal 16 is configured to calculate a second beam pointing angle according to the second train position information, and the ground base station 12 and the vehicle-mounted terminal 16 are configured with an antenna array for simulating a beamforming structure, the antennas in the antenna array are millimeter wave array antennas, and the number of antennas in the antenna array of the ground base station 12 is equal to the number of antennas in the antenna array of the vehicle-mounted terminal 16.

[0100] a beamforming device (not shown) for jointly beamforming antennas in the ground base station antenna array and antennas in the vehicle terminal antenna array according to the first beam pointing angle and the second beam pointing angle.

[0101] wherein the ground inductive loop positioning device is connected to the ground base station, and the vehicle laser coding positioning device is connected to the vehicle terminal.

[0102] Through the above technical solution, in the process of train running, each positioning device continuously provides real-time position information to the ground base station and the vehicle terminal in the train-ground communication system, and the ground base station and the vehicle terminal correspondingly continuously calculate the corresponding beam pointing angle and perform beamforming on the array antenna according to the beam pointing angle, to realize real-time tracking. By using the millimeter wave array antenna at both the transmitting end and the receiving end, the beamforming is performed in the direct direction through the beam pointing angle calculated in real time, to form a very high array gain, to reduce the array gain in the non-direct direction to the greatest extent, to reduce the number of reflection paths, and to reduce the complexity of channel equalization at the receiving end.

[0103] According to an embodiment of the present application, the ground base station 12 calculates the first beam pointing angle according to the first train position information, which includes:

[0104] determining a first train two-dimensional coordinate of the train in a predetermined angle coordinate system and a first base station two-dimensional coordinate of the ground base station in the predetermined angle coordinate system according to the first train position information, the first train two-dimensional coordinate including a first train horizontal coordinate and a first train vertical coordinate, and the first base station two-dimensional coordinate including a first base station horizontal coordinate and a first base station vertical coordinate,

[0105] calculating the first beam pointing angle according to the first train two-dimensional coordinate and the first base station two-dimensional coordinate;

[0106] The vehicle terminal 16 calculates the second beam pointing angle according to the second train position information, which includes:

[0107] determining a second train two-dimensional coordinate of the train in a predetermined angle coordinate system and a second base station two-dimensional coordinate of the ground base station in the predetermined angle coordinate system according to the second train position information, the second train two-dimensional coordinate including a second train horizontal coordinate and a second train vertical coordinate, and the second base station two-dimensional coordinate including a second base station horizontal coordinate and a second base station vertical coordinate,

[0108] calculating the second beam pointing angle according to the second train two-dimensional coordinate and the second base station two-dimensional coordinate.

[0109] According to an embodiment of the present application, the first beam pointing angle or the second beam pointing angle is calculated by the following formula:

[0110]

[0111] wherein θ is the first beam pointing angle or the second beam pointing angle, x1 is the first train horizontal coordinate or the second train horizontal coordinate, the first train vertical coordinate or the second train vertical coordinate is 0, x2 is the first base station horizontal coordinate or the second base station horizontal coordinate, and h is the first base station vertical coordinate or the second base station vertical coordinate.

[0112] According to an embodiment of the present application, the joint beamforming of the antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle-mounted terminal according to the first beam pointing angle and the second beam pointing angle comprises:

[0113] obtaining a normalized pointing vector according to the first beam pointing angle and the second beam pointing angle;

[0114] determining a beamforming vector according to the normalized pointing vector;

[0115] jointly beamforming the antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle-mounted terminal according to the beamforming vector.

[0116] According to an embodiment of the present application, in the case that only one train runs in the coverage range of the single ground base station, the beamforming vector is equal to the normalized pointing vector, and the beamforming vector is represented by the following formula:

[0117]

[0118] wherein w(N, θ) is the beamforming vector, and N is the number of antennas in the antenna array of the ground base station or the number of antennas in the antenna array of the vehicle-mounted terminal.

[0119] Figure 2 The described system corresponds to the described method, and specific examples can refer to the description of the described method, which will not be described here again. Figure 1 The described method corresponds to the described system, and specific examples can refer to the description of the described system, which will not be described here again. Figure 1 The described method corresponds to the described system, and specific examples can refer to the description of the described system, which will not be described here again.

[0120] Figure 3 A beam gain diagram according to an embodiment of the present application is shown.

[0121] At different angles The beam gain can be calculated by the following formula (that is, the gain can be calculated by selecting angles with a predetermined granularity in the corresponding angle range):

[0122]

[0123] As Figure 3As shown, wherein taking theta =-0.35 as an example, the beam gain diagrams of different numbers of array antennas N = 4, 8, 16 are shown.

[0124] From Figure 3 It can be seen that the greater N is, the narrower the beam width is, and there is a significant normalized main lobe array gain at the beam pointing angle theta =-0.35, and the sidelobe array gain at other angles can also be further reduced as N increases. For the omnidirectional single antenna, the gain in almost all directions is 1, that is to say, there will be a direct path, a one-time reflection path, and a plurality of multiple reflection paths between the transmitting and receiving ends; for the array antenna with analog beamforming, the antenna gain will concentrate the transmitting power on the direct path angle, and the power in other directions is very small, 1 / 5 or even lower than the direct path direction, and the number of generated multipaths can be far less than that using the omnidirectional antenna.

[0125] Considering the configuration cost of the antennas at the transmitting and receiving ends, the beam width of 16 antennas can meet the demand, and there is no need to be too narrow, that is, the ground base station and the vehicle-mounted terminal both preferably use 16 antennas to form an array.

[0126] In the description of the present application, it should be understood that the orientation words such as "front, rear, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and in the absence of contrary indications, these orientation words do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0127] For the convenience of description, spatial relative terms such as "above", "upper", "on", "upper surface", "upper", etc. can be used herein to describe the spatial positional relationship of one device or feature with respect to other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the devices described in the drawings. For example, if the devices in the drawings are inverted, the device described as "above" or "above" other devices or structures will be positioned "below" or "below" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0128] In addition, it should be noted that the use of "first", "second", and the like words to qualify parts is merely for the convenience of distinguishing the corresponding parts, and the above words have no special meaning unless otherwise stated, and therefore cannot be understood as limiting the scope of protection of the present application.

[0129] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made by those skilled in the art based on the spirit and principles of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for beamforming of train-ground communication of a super high-speed maglev train, characterized in that, The method comprises: The ground inductive loop positioning device sends the first train position information to the ground base station in real time, and the vehicle-mounted laser coding positioning device sends the second train position information to the vehicle-mounted terminal in real time, the ground base station and the vehicle-mounted terminal are provided with an antenna array for simulating a beamforming structure, the antennas in the antenna array are millimeter wave array antennas, the number of antennas in the antenna array of the ground base station is equal to the number of antennas in the antenna array of the vehicle-mounted terminal; The ground base station calculates a first beam pointing angle according to the first train position information, and the vehicle-mounted terminal calculates a second beam pointing angle according to the second train position information; The antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle-mounted terminal are jointly beamformed according to the first beam pointing angle and the second beam pointing angle.

2. The method of claim 1, wherein, The ground base station calculates a first beam pointing angle according to the first train position information, and the vehicle-mounted terminal calculates a second beam pointing angle according to the second train position information; The first train two-dimensional coordinates of the train in a predetermined angle coordinate system and the first base station two-dimensional coordinates of the ground base station in the predetermined angle coordinate system are determined according to the first train position information, the first train two-dimensional coordinates include a first train horizontal coordinate and a first train vertical coordinate, and the first base station two-dimensional coordinates include a first base station horizontal coordinate and a first base station vertical coordinate, The first beam pointing angle is calculated according to the first train two-dimensional coordinates and the first base station two-dimensional coordinates; The second train two-dimensional coordinates of the train in a predetermined angle coordinate system and the second base station two-dimensional coordinates of the ground base station in the predetermined angle coordinate system are determined according to the second train position information, the second train two-dimensional coordinates include a second train horizontal coordinate and a second train vertical coordinate, and the second base station two-dimensional coordinates include a second base station horizontal coordinate and a second base station vertical coordinate, The second beam pointing angle is calculated according to the second train two-dimensional coordinates and the second base station two-dimensional coordinates. The first beam pointing angle or the second beam pointing angle is calculated by the following formula:

3. The method of claim 2, wherein, Wherein, θ is the first beam pointing angle or the second beam pointing angle, x1 is the first train horizontal coordinate or the second train horizontal coordinate, the first train vertical coordinate or the second train vertical coordinate is 0, x2 is the first base station horizontal coordinate or the second base station horizontal coordinate, and h is the first base station vertical coordinate or the second base station vertical coordinate. The antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle-mounted terminal are jointly beamformed according to the first beam pointing angle and the second beam pointing angle, which comprises:

4. The method of claim 3, wherein, A normalized pointing vector is obtained according to the first beam pointing angle and the second beam pointing angle; A beamforming vector is determined according to the normalized pointing vector; The antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle-mounted terminal are jointly beamformed according to the beamforming vector. In the case that only one train runs in the coverage range of a single ground base station, the beamforming vector is equal to the normalized pointing vector, and the beamforming vector is represented by the following formula:

5. The method of claim 4, wherein, ​ Wherein, w(n, θ) is a beamforming vector, and N is the number of antennas in the antenna array of the ground base station or the number of antennas in the antenna array of the vehicle terminal.

6. A kind of super high-speed maglev train ground communication beamforming system, characterized by, The system comprises: A ground inductive loop positioning device configured to transmit first train position information to the ground base station in real time; A vehicle laser coding positioning device configured to transmit second train position information to the vehicle terminal in real time; A ground base station configured to calculate a first beam pointing angle based on the first train position information; A vehicle terminal configured to calculate a second beam pointing angle based on the second train position information, wherein the ground base station and the vehicle terminal are provided with an antenna array for simulating a beamforming structure, the antennas in the antenna array are millimeter wave array antennas, the number of antennas in the antenna array of the ground base station is equal to the number of antennas in the antenna array of the vehicle terminal; A beamforming device configured to perform joint beamforming on the antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle terminal based on the first beam pointing angle and the second beam pointing angle.

7. The system of claim 6, wherein, The ground base station calculates the first beam pointing angle based on the first train position information, which comprises: determining a first train two-dimensional coordinate of the train in a predetermined angle coordinate system and a first base station two-dimensional coordinate of the ground base station in the predetermined angle coordinate system based on the first train position information, wherein the first train two-dimensional coordinate comprises a first train horizontal coordinate and a first train vertical coordinate, and the first base station two-dimensional coordinate comprises a first base station horizontal coordinate and a first base station vertical coordinate, calculating the first beam pointing angle based on the first train two-dimensional coordinate and the first base station two-dimensional coordinate. The vehicle terminal calculates the second beam pointing angle based on the second train position information, which comprises: determining a second train two-dimensional coordinate of the train in a predetermined angle coordinate system and a second base station two-dimensional coordinate of the ground base station in the predetermined angle coordinate system based on the second train position information, wherein the second train two-dimensional coordinate comprises a second train horizontal coordinate and a second train vertical coordinate, and the second base station two-dimensional coordinate comprises a second base station horizontal coordinate and a second base station vertical coordinate, calculating the second beam pointing angle based on the second train two-dimensional coordinate and the second base station two-dimensional coordinate.

8. The system of claim 7, wherein, The first beam pointing angle or the second beam pointing angle is calculated by the following formula: wherein θ is the first beam pointing angle or the second beam pointing angle, x1 is the first train horizontal coordinate or the second train horizontal coordinate, the first train vertical coordinate or the second train vertical coordinate is 0, x2 is the first base station horizontal coordinate or the second base station horizontal coordinate, and h is the first base station vertical coordinate or the second base station vertical coordinate.

9. The system of claim 8, wherein, The beamforming device performs joint beamforming on the antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle terminal based on the first beam pointing angle and the second beam pointing angle, which comprises: obtaining a normalized pointing vector based on the first beam pointing angle and the second beam pointing angle; determining a beamforming vector based on the normalized pointing vector; performing joint beamforming on the antennas in the antenna array of the ground base station and the antennas in the antenna array of the vehicle terminal based on the beamforming vector.

10. The system of claim 9, wherein, In the case that only one train runs in the coverage range of the single ground base station, the beamforming vector is equal to the normalized pointing vector, and the beamforming vector is represented by the following formula: wherein w(n, θ) is the beamforming vector, and N is the number of antennas in the antenna array of the ground base station or the number of antennas in the antenna array of the vehicle-mounted terminal.

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