Phased array terminal intelligent beam reconstruction method based on air interface

Abstract

The invention discloses a phased array terminal intelligent beam reconstruction method based on an air interface, and belongs to the technical field of satellite communication. The method comprises the following steps: issuing ephemeris through an air interface; resolving an angle; calculating a pencil beam weight; initializing a weight vector; carrying out pencil-shaped wave beam splicing to realize wave beam reconstruction; calculating the gain of each pointing angle; updating the weight vector; repeating the iteration process; and outputting a beam reconstruction weight. According to the invention, a plurality of beams can be formed to respectively align with a plurality of satellites, the gain fluctuation of each pointing angle is suppressed, the calculation complexity is low, and the increase of cost, volume and power consumption caused by configuring a plurality of sets of weights for a simulated phased array is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite communications, and in particular relates to an intelligent beam reconstruction method for a phased array terminal based on an air interface. Background Art

[0002] Phased array antennas are antenna arrays composed of multiple antenna units distributed at different locations in space. The transmit / receive signals of each antenna unit are processed with amplitude and phase weighting, which can improve antenna gain, perform flexible beam control and interference suppression. Thanks to the above advantages, phased array antenna technology has been widely used in satellite communication terminal stations in recent years.

[0003] Traditional satellite communication terminal antennas can only form a single beam and can only point to one satellite at a time. When faced with complex services, they need to switch between multiple satellites, causing communication interruptions. In order to solve this problem and improve the efficiency and flexibility of the system, multi-beam technology can be used for beam reconstruction: through the existing satellite communication link and air interface protocol, the gateway station can send the ephemeris of multiple target satellites to the terminal station. The terminal station calculates the corresponding pointing angles of multiple satellites based on the ephemeris, adjusts the amplitude and phase weighting of the terminal phased array antenna unit, and simultaneously forms multiple beams with different directions to aim at multiple satellites, realizing intelligent beam reconstruction of the phased array terminal.

[0004] There are three common implementation methods of multi-beam technology:

[0005] (1) Configure multiple sets of weights, each set of weights forms a beam;

[0006] (2) Use open-loop adaptive algorithms such as linear constrained minimum variance and orthogonal projection to calculate weights;

[0007] (3) Use convex optimization, particle swarm and other algorithms to iteratively optimize the directional graph.

[0008] Among them, for digital phased arrays, method (1) can use different digital weights to perform spatial filtering on the signal in the digital domain, which is easy to implement. For analog phased arrays, multiple sets of phase shifters and attenuators need to be configured, which increases the hardware cost and also increases the volume and power consumption of the system. The computational complexity of methods (2) and (3) is relatively high, and they are not suitable for application scenarios with limited computing resources and high real-time requirements. Among them, method (2) involves matrix inversion, and its computational complexity increases significantly with the increase of array size. Summary of the invention

[0009] The purpose of the present invention is to address the problems existing in the above-mentioned analog phased array forming multiple beams, and propose an intelligent beam reconstruction method for phased array terminals based on air interfaces. The present invention sends the ephemeris of the target satellite through the air interface, solves multiple pointing angles, performs pencil beam splicing iterative calculations, forms multiple beams that are respectively aimed at multiple satellites, and suppresses the gain fluctuation of each pointing angle, with low computational complexity, and avoids the increase in cost, volume, and power consumption caused by configuring multiple sets of weights.

[0010] The technical solution adopted by the present invention is:

[0011] An intelligent beam reconstruction method for a phased array terminal based on an air interface comprises the following steps:

[0012] Step 1: The gateway sends the ephemeris of N target satellites to the terminal station through the satellite communication link and air interface protocol;

[0013] Step 2: The terminal station calculates N pointing angles through ephemeris

[0014] Step 3: Calculate the pencil beam weights w1, w2, ..., w at each pointing angle N ;

[0015] Step 4: Initialize the weight vector: s = [s1, s2, ..., s N ]=[1,1,...,1];

[0016] Step 5: Perform pencil beam splicing to achieve beam reconstruction. The calculation method of beam reconstruction weight w is as follows:

[0017]

[0018] Step 6: Calculate the gain G1, G2, ..., G of the beam reconstruction pattern at each pointing angle N , and find the maximum value G max ;

[0019] Step 7: Update the weight vector as follows:

[0020]

[0021] Wherein, Δ is the gain difference threshold, μ is the iteration step, n=1,2,…,N;

[0022] Step 8: Repeat steps 5 to 7 until the iteration stop condition is met;

[0023] Step 9: Output the beam reconstruction weight w to complete the beam reconstruction.

[0024] Furthermore, among the pointing angles described in step 2, the nth pointing angle Q n and are the off-axis angle and azimuth angle of the terminal phased array antenna pointing to the nth target satellite, n=1,2,…,N.

[0025] Furthermore, the pencil beam weights described in step 3 are calculated as follows:

[0026] Assume that the number of array elements of the phased array antenna is M, and the coordinates of the mth array element are (x m ,y m ), m=1,2,…,M, the carrier frequency is f, and the speed of light is c; for the nth pointing angle, n=1,2,…,N, the phase difference of the mth array element relative to the zero reference point is:

[0027]

[0028] The steering vector corresponding to the nth pointing angle is:

[0029]

[0030] Where, j is the imaginary unit;

[0031] The pencil beam weight of the nth pointing angle is equal to the steering vector corresponding to the angle, that is:

[0032] w n =v n .

[0033] Furthermore, the gain of the beam reconstruction pattern at each pointing angle described in step 6 is calculated as follows:

[0034] The gain G of the directivity pattern at the nth pointing angle n for:

[0035]

[0036] The superscript H represents conjugate transpose, and * represents conjugation.

[0037] Furthermore, the condition for stopping iteration in step 8 is:

[0038] Gains at various pointing angles G1, G2, ..., G N With the maximum value G max The difference is no greater than the gain difference threshold Δ;

[0039] Or, the number of iterations reaches the upper limit.

[0040] The beneficial effects of the present invention are:

[0041] 1. In the iterative process, the present invention updates the weight vector according to the difference between the gain of the directional pattern at each directional angle and the maximum value thereof, so that the gain fluctuation at each directional angle is suppressed.

[0042] 2. The present invention only calculates the sampling points of the directional pattern at each pointing angle in a single iteration, without calculating the entire directional pattern; when updating the weight vector, only a fixed iteration step value is added or remains unchanged. In summary, the method provided by the present invention has low computational complexity.

[0043] 3. The present invention only requires one set of weights to form multiple beams, thus avoiding the increase in cost, volume, and power consumption caused by configuring multiple sets of weights for analog phased arrays. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The present invention provides a flow chart of a phased array terminal intelligent beam reconstruction method.

[0045] Figure 2 It is the array surface adopted in the specific embodiment.

[0046] Figure 3 It is the gain fluctuation decreasing curve during the iteration process.

[0047] Figure 4 It is the 3D direction map after the iteration is completed.

[0048] Figure 5 It is the comparison of 2D directional images before and after iteration. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below in conjunction with specific embodiments and drawings.

[0050] An intelligent beam reconstruction method for a phased array terminal based on an air interface comprises the following steps:

[0051] Step 1: The gateway sends the ephemeris of N target satellites to the terminal station through the satellite communication link and air interface protocol;

[0052] Step 2: The terminal station calculates N pointing angles (q1, j1), (q2, j2), ..., (q N ,j N ); where the nth pointing angle (q n ,j n ) n and j n are the off-axis angle and azimuth angle of the terminal phased array antenna pointing to the nth target satellite (n=1,2,…,N);

[0053] Step 3: Calculate the pencil beam weights w1, w2, ..., w at each pointing angleN ; The calculation method of pencil beam weight is as follows:

[0054] Assume that the number of array elements of the phased array antenna is M, and the coordinates of the mth (m=1,2,…,M)th array element are (x m ,y m ), the carrier frequency is f, and the speed of light is c. For the nth pointing angle, the phase difference of the mth array element relative to the zero reference point is:

[0055]

[0056] The steering vector corresponding to the nth pointing angle is:

[0057]

[0058] The pencil beam weight of the nth pointing angle is equal to the steering vector corresponding to the angle, that is:

[0059] w n =v n ;

[0060] Step 4: Initialize the weight vector: s = [s1, s2, ..., s N ]=[1,1,...,1];

[0061] Step 5: Perform pencil beam splicing to achieve beam reconstruction. The beam reconstruction weight calculation method is as follows:

[0062]

[0063] Step 6: Calculate the gain G1, G2, ..., G of the beam reconstruction pattern at each pointing angle N , and find the maximum value G max ; The gain calculation method is as follows:

[0064] The gain of the directivity pattern at the nth pointing angle is:

[0065]

[0066] Step 7: Update the weight vector as follows:

[0067]

[0068] Where Δ is the gain difference threshold, μ is the iteration step size;

[0069] Step 8: Repeat steps 5 to 7 until the stop iteration condition is met; the stop iteration condition can be set as "the gain G1, G2, ..., G N With the maximum value G maxThe difference is not greater than the gain difference threshold Δ" or "the number of iterations reaches the upper limit";

[0070] Step 9: Output the beam reconstruction weight w.

[0071] Here is a more specific example:

[0072] An intelligent beam reconstruction method for phased array terminal based on air interface, the array surface used is as follows Figure 2 As shown in the figure, the array is arranged in a rectangular array, the number of array elements M = 4096, and the distance between adjacent array elements is 10 mm. The carrier frequency f is set to 15 GHz. Figure 1 As shown, the specific embodiment includes the following steps:

[0073] Step 1: There are four target satellites, all of which are synchronous orbit satellites, with longitudes of 90°E, 91°E, 92°E, and 100°E. The gateway sends the ephemeris of the four target satellites to the terminal station through the satellite communication link and air interface protocol;

[0074] Step 2: Assume that the attitude angle of the terminal station carrier platform is 120° yaw angle, 30° pitch angle, and 0° roll angle. The four pointing angles can be calculated using the attitude angle and the satellite longitude in the ephemeris:

[0075]

[0076] Step 3: Calculate the pencil beam weights w1, w2, w3, w4 at each pointing angle. The calculation method is as follows:

[0077] The coordinates (x m ,y m ) can be calculated through the array layout and the array element spacing, and the speed of light c is 3×10 8 m / s. For the nth pointing angle (n=1,2,3,4), the phase difference of the mth array element relative to the zero reference point is:

[0078]

[0079] The steering vector corresponding to the nth pointing angle is:

[0080]

[0081] The pencil beam weight of the nth pointing angle is equal to the steering vector corresponding to the angle, that is:

[0082] w n =v n

[0083] Step 4: Initialize the weight vector: s = [s1, s2, s3, s4] = [1, 1, 1, 1];

[0084] Step 5: Perform pencil beam splicing to achieve beam reconstruction. The beam reconstruction weight calculation method is as follows:

[0085]

[0086] Step 6: Calculate the gains G1, G2, G3, and G4 of the beam reconstruction pattern at each pointing angle. The calculation method is as follows:

[0087] The gain of the directivity pattern at the nth pointing angle is:

[0088]

[0089] After calculating the gain of each pointing angle, let G max Equal to the maximum value among G1, G2, G3, G4;

[0090] Step 7: Set the gain difference threshold D = 1dB, and the iteration step length m = 0.1. Update the weight vector as follows:

[0091]

[0092] Step 8: Repeat steps 5 to 7 until the gains G1, G2, G3, G4 of each pointing angle are equal to the maximum value G max The difference is no greater than the gain difference threshold of 1dB;

[0093] Step 9: Output the beam reconstruction weight w.

[0094] The gain fluctuation decrease curve during the iteration process is as follows Figure 3 As shown, it can be seen that during the iteration process, the gain fluctuation continuously decreases until it is less than the gain difference threshold of 1 dB. Figure 4 It is the 3D radiation pattern after the iteration is completed. The four cross-marked points in the figure are the pointing angles of the four target satellites relative to the terminal phased array antenna. It can be seen that the radiation pattern forms a main lobe at the four pointing angles. Figure 5 It is a comparison of the 2D directional diagrams before and after iteration. The horizontal axis is longitude and there are 4 dotted lines perpendicular to the horizontal axis marking the longitudes of the 4 target satellites. It can be seen that the gain fluctuation corresponding to each satellite before iteration is greater than 16 dB, and the gain fluctuation after iteration is less than 1 dB.

[0095] In summary, the present invention can form multiple beams to aim at multiple satellites respectively, the gain fluctuation of each pointing angle is suppressed, the calculation complexity is low, and the increase in cost, volume and power consumption caused by configuring multiple sets of weights for analog phased arrays is avoided.

Claims

1. An intelligent beam reconstruction method for a phased array terminal based on an air interface, characterized in that: The following steps are involved: Step 1: The gateway sends the ephemeris of N target satellites to the terminal station through the satellite communication link and air interface protocol; Step 2: The terminal station calculates N pointing angles through ephemeris Step 3: Calculate the pencil beam weights w1, w2, ..., w at each pointing angle N ; Step 4: Initialize the weight vector: s = [s1, s2, ..., s N ]=[1,1,...,1]; Step 5: Perform pencil beam splicing to achieve beam reconstruction. The calculation method of beam reconstruction weight w is as follows: Step 6: Calculate the gain G1, G2, ..., G of the beam reconstruction pattern at each pointing angle N , and find the maximum value G max ; Step 7: Update the weight vector as follows: Wherein, Δ is the gain difference threshold, μ is the iteration step, n=1,2,…,N; Step 8: Repeat steps 5 to 7 until the iteration stop condition is met; Step 9: Output the beam reconstruction weight w to complete the beam reconstruction.

2. According to the air interface-based phased array terminal intelligent beam reconstruction method according to claim 1, it is characterized in that: Among the pointing angles described in step 2, the nth pointing angle Q n and are the off-axis angle and azimuth angle of the terminal phased array antenna pointing to the nth target satellite, n=1,2,…,N.

3. The method for intelligent beam reconstruction of a phased array terminal based on an air interface according to claim 1, characterized in that: The pencil beam weights described in step 3 are calculated as follows: Assume that the number of array elements of the phased array antenna is M, and the coordinates of the mth array element are (x m ,y m ), m=1,2,…,M, the carrier frequency is f, and the speed of light is c; for the nth pointing angle, n=1,2,…,N, the phase difference of the mth array element relative to the zero reference point is: The steering vector corresponding to the nth pointing angle is: Where, j is the imaginary unit; The pencil beam weight of the nth pointing angle is equal to the steering vector corresponding to the angle, that is: w n =v n 。 4. The method for intelligent beam reconstruction of a phased array terminal based on an air interface according to claim 3, characterized in that: The gain of the beam reconstruction pattern at each pointing angle described in step 6 is calculated as follows: The gain G of the directivity pattern at the nth pointing angle n for: The superscript H represents conjugate transpose, and * represents conjugation.

5. The method for intelligent beam reconstruction of a phased array terminal based on an air interface according to claim 1, characterized in that: The stop iteration condition described in step 8 is: Gains at various pointing angles G1, G2, ..., G N With the maximum value G max The difference is no greater than the gain difference threshold Δ; Or, the number of iterations reaches the upper limit.

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