Frequency spectrum sharing method of satellite carrying phased-array antenna

Abstract

The invention discloses a spectrum sharing method for a satellite carrying a phased-array antenna, and the method mainly comprises the steps: determining a main lobe signal and a side lobe signal in a received signal according to a spectrum sensing result and a wave beam coverage range; setting a blocking matrix, and suppressing a main lobe signal; calculating a covariance matrix and completing decomposition by using the blocked signal; independently setting a virtual interference matrix for each side lobe signal; and reconstructing a covariance matrix, and carrying out antenna weight calculation. According to the method, an asymmetric interference notch with any width can be independently generated for each interference source on a satellite, the receiving of normal main lobe signals is not influenced, the method is suitable for a same-frequency sharing scene in which main lobe communication users and side lobe spectrum sharing users are densely distributed, and the spectrum sharing of a low-orbit constellation is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite communications, and mainly relates to a spectrum sharing method for a satellite equipped with a phased array antenna. Background Art

[0002] In the future, large-scale low-orbit constellations will be the main development direction of space-based information systems. Starlink, OneWeb, Kuiper, and AST constellations in Europe and the United States have been successively constructed, and my country's low-orbit Internet, Qianfan G60 and other constellations are also accelerating their development, which has brought about significant frequency and orbit resource shortages. At the same time, the evolutionary trend of satellite-ground integration has brought about new application scenarios for mobile phones to connect directly to satellites. With the emergence of new terminal equipment, new communication systems, and new business models, large-scale satellite-ground connections have further exacerbated the problem of satellite-ground and inter-satellite spectrum sharing.

[0003] Traditional interference avoidance methods can be roughly divided into three categories: power control, spectrum sharing, and spatial isolation. Power control methods are often based on the interference criteria defined by the ITU. By controlling the transmit power of LEO satellites and ground stations, the transmit power is dynamically adjusted according to the actual interference situation, thereby reducing interference to other systems; spatial isolation refers to adjusting the satellite pointing of ground stations of different systems to avoid the co-linear receiving pointing of different satellite systems, thereby reducing the worst co-linear interference and achieving the purpose of interference mitigation; spectrum sharing technology is currently an important means to solve the problem of co-frequency interference between satellite systems. By flexibly configuring spectrum resources at a specific time or location, the probability of interference between different systems sharing the same frequency band is minimized.

[0004] At present, relevant scholars and institutions have carried out research on LEO constellation frequency interference avoidance strategies. Existing literature has conducted a detailed analysis of the causes of interference problems between LEO communication constellations, but there is still a lack of further in-depth research on frequency sharing strategies between LEO constellations. The relative position of LEO satellites to the ground is time-varying, and the beam pointing of LEO ground stations requires high-frequency switching, so the selection of isolation angles requires further analysis. Secondly, the large-scale characteristics of the LEO constellation mean that even if there is no mainlobe interference signal in the received signal of the ground station, the aggregate interference signal leaked from the sidelobe may cause harmful interference. In the scenario of direct connection between satellites and ground mobile phones, for the satellite receiving beam, there are a large number of interference signals in both the mainlobe area and the sidelobe area. Directly using traditional spatial interference suppression methods will cause the mainlobe beam to be distorted and unable to work normally. Summary of the invention

[0005] The object of the present invention is to provide a spectrum sharing method for satellites equipped with phased array antennas, which can effectively suppress sidelobe interference and improve the capacity of satellite systems.

[0006] To achieve the above object, the present invention adopts the following technical solutions, including:

[0007] Step 1: Determine the main lobe signal and the side lobe signal in the received signal according to the spectrum sensing result of the uplink received signal X(t) and the coverage range of the satellite receiving beam;

[0008] Step 2: Set the blocking matrix B, suppress the main lobe signal, and obtain the blocked signal Y(t);

[0009] Step 3: Calculate the covariance matrix Z using the blocked signal Y(t) and decompose the covariance matrix Z to obtain the eigenvectors [u1,u2,…,u K ];

[0010] Step 4: independently setting a virtual interference matrix V for each of the sidelobe signals;

[0011] Step 5: Reconstruct the covariance matrix And calculate the antenna weights.

[0012] As a further improvement of the present invention, in step 1, the spectrum sensing result is The satellite receiving beam coverage range is [θ 3dB,low ,θ 3dB,high ]、 in, are the elevation angle and azimuth angle corresponding to the center direction of the beam respectively, and N is the total number of signals received.

[0013] As a further improvement of the present invention, in step 2,

[0014] The blocking matrix B is:

[0015]

[0016] in, represents the Coronavirus product,

[0017]

[0018] As a further improvement of the present invention, in step 2,

[0019] The blocked signal Y(t) is:

[0020] Y(t)=B H X(t),

[0021] in,[] H represents the conjugate transpose.

[0022] As a further improvement of the present invention, in step 3,

[0023] The covariance matrix Z is eigendecomposed into:

[0024]

[0025] where λ k and u k are the kth eigenvalue and kth eigenvector respectively.

[0026] As a further improvement of the present invention, the kth eigenvector is:

[0027]

[0028] in, refers to the guidance vector of the qth influence, b qk is the weight.

[0029] As a further improvement of the present invention, in step 4, the virtual interference matrix V is:

[0030] [V] α,β =sinc((m x -n x )d x W x / λ)·sinc((m y -n y )d y W y / λ),

[0031] in, m y =α mod M, n y =β mod M, represents rounding to the nearest negative infinity integer, mod is the modulus after division, [V] α,β represents the element of the matrix at row α and column β.

[0032] As a further improvement of the present invention, in step 5, the covariance matrix is ​​reconstructed

[0033] The ideal covariance matrix is ​​composed of:

[0034]

[0035] After adding the interference matrix, the reconstructed covariance matrix becomes:

[0036]

[0037] where ⊙ is the Hadamard product.

[0038] As a further improvement of the present invention, in step 5, according to the estimated covariance matrix and blocking vector Get the antenna weight ω:

[0039]

[0040] Among them, θ0 and are the elevation and azimuth angles corresponding to the beam center direction, respectively.

[0041] Beneficial effects:

[0042] The present invention discloses a spectrum sharing method for a satellite equipped with a phased array antenna. According to the spectrum sensing result and the beam coverage, the main lobe and side lobe receiving signals are determined, a blocking matrix is ​​set, the main lobe receiving signal in the receiving signal is suppressed, the covariance matrix is ​​calculated and decomposed, and a virtual interference matrix is ​​independently set for each side lobe signal. Then, the covariance matrix is ​​reconstructed, and antenna weight calculation is performed. The present invention can generate an interference notch of arbitrary width and asymmetry for each interference source on the satellite, and does not affect the reception of normal main lobe signals. It is suitable for the same frequency sharing scenario where the main lobe communication users and the side lobe spectrum sharing users are densely distributed, and the spectrum sharing of the low-orbit constellation is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is an implementation flow chart of an embodiment of the present invention;

[0044] Figure 2 is a characteristic value distribution diagram of an embodiment of the present invention;

[0045] Figure 3 The antenna pattern after the notch is generated according to the embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0048] 1. Experimental scenario:

[0049] refer to Figure 1 The specific implementation steps of the present invention are as follows:

[0050] Step 1: According to the spectrum sensing result of the uplink received signal X(t) and the coverage range of the satellite receiving beam, the main lobe signal and the side lobe signal in the received signal are determined.

[0051] The spectrum sensing result is The coverage of the satellite receiving beam is [θ 3dB,low ,θ 3dB,high ]、 in, are the elevation angle and azimuth angle corresponding to the center direction of the beam respectively, and N is the total number of signals received.

[0052] Step 2: Set the blocking matrix B, suppress the main lobe signal, and obtain the blocked signal Y(t).

[0053] The blocking matrix B is:

[0054]

[0055] in, represents the Coronavirus product,

[0056]

[0057] The signal Y(t) after blocking is:

[0058] Y(t)=B H X(t),

[0059] in,[] H represents the conjugate transpose.

[0060] Step 3: Use the blocked signal Y(t) to calculate the covariance matrix Z and decompose the covariance matrix Z to obtain the eigenvectors [u1,u2,…,u K ].

[0061] The covariance matrix Z eigendecomposition is:

[0062]

[0063] where λ k and u k are the kth eigenvalue and kth eigenvector respectively.

[0064] The kth eigenvector is:

[0065]

[0066] in, refers to the guidance vector of the qth influence, b qk is the weight.

[0067] Step 4: Set the virtual interference matrix V independently for each sidelobe signal.

[0068] Virtual interference matrix V:

[0069] [V] α,β =sinc((m x -n x )d x W x / λ)·sinc((m y -n y )d y W y / λ),

[0070] in, m y =α mod M, n y =β mod M, represents rounding to the nearest negative infinity integer, mod is the modulus after division, [V] α,β represents the element of the matrix at row α and column β.

[0071] Step 5: Reconstruct the covariance matrix And calculate the antenna weights.

[0072] The ideal covariance matrix is ​​composed of:

[0073]

[0074] After adding the interference matrix, the reconstructed covariance matrix becomes:

[0075]

[0076] where ⊙ is the Hadamard product.

[0077] According to the estimated covariance matrix and blocking vector Get the antenna weight ω:

[0078]

[0079] Among them, θ0 and are the elevation and azimuth angles corresponding to the beam center direction, respectively.

[0080] 2. Experimental content and results:

[0081] Measure the signals received in all directions at the satellite position, set the azimuth and elevation angle range of its main lobe. Set an interference source at a random position, set the interference-to-noise ratio to -10dB, and point the receiving antenna pattern to the side lobe position of the satellite.

[0082] like Figure 2 As shown, a curve of characteristic value change is obtained.

[0083] like Figure 3 As shown in Figure 1, the antenna pattern after the notch is generated is obtained. Figure 3 It can be seen that by blocking the main lobe signal and injecting virtual signals into the side lobe to achieve complete spectrum sharing, a notch of a specified width can be generated on the side lobe without affecting the main lobe signal.

[0084] In summary, the present invention provides a spectrum sharing method for a satellite equipped with a phased array antenna, which determines the main lobe and side lobe receiving signals according to the spectrum sensing results and the beam coverage, sets a blocking matrix, suppresses the main lobe receiving signal in the receiving signal, calculates the covariance matrix and completes the decomposition, and independently sets a virtual interference matrix for each side lobe signal, then reconstructs the covariance matrix, and performs antenna weight calculation. The present invention generates an interference notch of arbitrary width and asymmetry for each interference source on the satellite, and does not affect the reception of normal main lobe signals. It is suitable for the same-frequency sharing scenario where the main lobe communication users and the side lobe spectrum sharing users are densely distributed, and realizes the spectrum sharing of the low-orbit constellation.

[0085] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A spectrum sharing method for a satellite equipped with a phased array antenna, characterized in that: include: Step 1: Determine the main lobe signal and the side lobe signal in the received signal according to the spectrum sensing result of the uplink received signal X(t) and the coverage range of the satellite receiving beam; Step 2, setting a blocking matrix B, suppressing the main lobe signal, and obtaining a blocked signal Y(t); Step 3: Calculate the covariance matrix Z using the blocked signal Y(t) and decompose the covariance matrix Z to obtain the eigenvectors [u1,u2,…,u K ]; Step 4: independently setting a virtual interference matrix V for each of the sidelobe signals; Step 5: Reconstruct the covariance matrix And calculate the antenna weights.

2. The spectrum sharing method for a satellite equipped with a phased array antenna according to claim 1, characterized in that: In step 1, the spectrum sensing result is The satellite receiving beam coverage range is [θ 3dB,low ,θ 3dB,high ]、 in, are the elevation angle and azimuth angle corresponding to the center direction of the beam, and N is the total number of signals received.

3. The spectrum sharing method for a satellite equipped with a phased array antenna according to claim 1, characterized in that: In the step 2, The blocking matrix B is: in, represents the Coronavirus product, 4. The spectrum sharing method for a satellite equipped with a phased array antenna according to claim 1, characterized in that: In the step 2, The blocked signal Y(t) is: Y(t)=B H X(t), in,[ ] H represents the conjugate transpose.

5. The spectrum sharing method for a satellite equipped with a phased array antenna according to claim 1, characterized in that: In step 3, The covariance matrix Z is eigendecomposed into: where λ k and u k are the kth eigenvalue and kth eigenvector respectively.

6. The spectrum sharing method for a satellite equipped with a phased array antenna according to claim 5, characterized in that: The kth eigenvector is: in, refers to the guidance vector of the qth influence, b qk is the weight.

7. The spectrum sharing method for a satellite equipped with a phased array antenna according to claim 1, characterized in that: In step 4, the virtual interference matrix V is: [V] α，β =sinc(m x -n x )d x W x / λ)·sinc((m y -n y )d y W y / λ), in m y =α mod M, n y =β mod M, represents rounding to the nearest negative infinity integer, mod is the modulus after division, [V] α,β represents the element of the matrix at row α and column β.

8. The spectrum sharing method for a satellite equipped with a phased array antenna according to claim 1, characterized in that: In step 5, the covariance matrix is ​​reconstructed The ideal covariance matrix is ​​composed of: After adding the interference matrix, the reconstructed covariance matrix becomes: where ⊙ is the Hadamard product.

9. The spectrum sharing method for a satellite equipped with a phased array antenna according to claim 8, characterized in that: In step 5, according to the estimated covariance matrix and blocking vector Get the antenna weight ω: Among them, θ0 and are the elevation and azimuth angles corresponding to the beam center direction, respectively.

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