An uplink spectrum sharing method in a satellite-ground fusion network

Abstract

The application provides an uplink spectrum sharing method in a satellite-terrestrial integrated network, which comprises the following steps: a satellite terminal acquires position information of a satellite and position information of a terrestrial communication system in a shared frequency band; the satellite terminal determines spectrum sensing parameters and throughput estimation values in an interleaving mode and transmission power and throughput estimation values in an overlapping mode based on the position information of the satellite and the terrestrial communication system; and the satellite terminal selects one of the two spectrum sharing modes of the interleaving mode and the overlapping mode with a larger throughput estimation value to perform data transmission of the uplink. The uplink spectrum sharing method of the application selects a spectrum sharing mode according to the position information of the satellite and the terrestrial communication system, optimizes spectrum sensing parameters or transmission power, improves the transmission throughput of the satellite terminal, avoids serious interference to the terrestrial system, and effectively improves the spectrum utilization efficiency of the satellite-terrestrial integrated network.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to an uplink spectrum sharing method in a satellite-ground fusion network. Background Art

[0002] Satellite and terrestrial communication systems are highly complementary in terms of coverage and transmission capacity, making satellite-ground converged networks a key development direction for 6G mobile communication systems. However, with the dense deployment of satellite and terrestrial communication systems and the explosive growth in service demand, spectrum scarcity has become a major obstacle to the development of satellite-ground converged networks. Sharing spectrum resources between satellite and terrestrial communication systems is an effective way to alleviate spectrum shortages, but effective spectrum management technologies are required to avoid co-channel interference between systems.

[0003] Consider the uplink spectrum sharing scenario of satellite communication system and ground communication system, wherein the ground communication system is the primary system and the satellite communication system is the secondary system. Due to the limited transmit power and transmit antenna gain of the ground terminal, and the long distance between the ground terminal and the satellite, the interference of the ground terminal to the satellite can be ignored. However, the transmit power and transmit antenna gain of the satellite terminal are usually high, so the interference of the satellite terminal to the ground base station needs to be focused on. When the satellite terminal uses the shared frequency band shared with the ground communication system for uplink transmission, the following two spectrum sharing modes can be used, namely interweave mode or underlay mode. Among them, the interweave mode means that the satellite terminal and the ground terminal can only transmit alternately on the shared frequency band and cannot transmit simultaneously, so for the interweave mode, when the satellite terminal detects that the ground communication system does not occupy the shared frequency band based on the spectrum sensing technology, the satellite terminal can access the frequency band for transmission; when it is detected that the ground communication system occupies the shared frequency band, the satellite terminal cannot access the frequency band. The underlay mode means that the satellite terminal and the ground terminal can transmit simultaneously on the shared frequency band. Therefore, for the underlay mode, the satellite terminal can transmit simultaneously with the ground terminal on the same frequency band, but the interference power to the ground base station needs to be controlled within a certain threshold to avoid causing the communication quality of the ground system to decline. The interweave mode and the underlay mode are two common frequency band access types in cognitive radio networks, see

F. Mehmeti and T. Spyropoulos, "Performance Analysis, Comparison, and Optimization of Interweave and Underlay Spectrum Access in Cognitive Radio Networks," IEEE Transactions on Vehicular Technology, vol. 67, no. 8, pp. 7143-7157, Aug. 2018

[0004] Satellite terminal antennas have high directivity. When the off-axis angle between the satellite terminal antenna and the terrestrial communication system (including the ground base station and the ground terminal) is large, the antenna gain of the satellite terminal antenna in the direction of the terrestrial communication system is low. In this case, when the satellite terminal uses an interleaved mode, to ensure a target detection probability, the satellite terminal needs to use a longer sensing time, resulting in lower satellite terminal throughput. When the satellite terminal uses an overlapping mode, the interference link channel gain of the satellite terminal to the ground base station is small, allowing the satellite terminal to use higher transmit power, thereby achieving higher throughput. Conversely, when the off-axis angle between the satellite terminal antenna and the terrestrial communication system is small, the satellite terminal using the overlapping mode needs to use lower transmit power to avoid severe interference with the ground base station. The interleaved mode effectively utilizes unused frequency bands for efficient transmission. Therefore, the satellite terminal should appropriately select a spectrum sharing mode based on the spatial location of the satellite and the terrestrial communication system to maximize its transmission throughput.

[0005] Based on this, it is necessary to propose a new uplink spectrum sharing method in the satellite-ground fusion network to improve the spectrum utilization efficiency of the satellite-ground fusion network. Summary of the Invention

[0006] The object of the present invention is to provide an uplink spectrum sharing method in a satellite-ground fusion network to improve the spectrum utilization efficiency of the satellite-ground fusion network.

[0007] To achieve the above-mentioned object, the present invention provides an uplink spectrum sharing method in a satellite-ground fusion network, which involves a terrestrial communication system and a satellite communication system that use a shared frequency band for uplink transmission, the terrestrial communication system including a ground terminal and a ground base station, and the satellite communication system including a satellite terminal and a satellite. The uplink spectrum sharing method includes:

[0008] S1: The satellite terminal obtains the location information of the satellite and the location information of the ground communication system sharing the frequency band;

[0009] S2: The satellite terminal determines the spectrum sensing parameters and throughput estimation value of the satellite terminal when the interleaving mode is adopted based on the satellite position information and the position information of the ground communication system;

[0010] S3: The satellite terminal determines the estimated transmit power and throughput of the satellite terminal when the overlap mode is used based on the satellite position information and the position information of the ground communication system;

[0011] S4: The satellite terminal selects a spectrum sharing mode with a larger throughput estimation value from the two spectrum sharing modes, the interleaved mode and the overlapped mode, to perform uplink data transmission.

[0012] Preferably, in the step S2, the spectrum sensing parameters include sensing time and energy detection threshold.

[0013] Preferably, the step S2 specifically includes:

[0014] S21: The satellite terminal calculates the maximum off-axis angle θ ter between the satellite terminal receiving antenna main lobe and the ground terminal, and the maximum distance d ter between the satellite terminal and the ground terminal based on the position information of the satellite and the position information of the ground communication system;

[0015] S22: The satellite terminal determines the worst sensing link signal-to-noise ratio estimate γ between the satellite terminal and the ground terminal based on the maximum off-axis angle θ ter and the maximum distance d ter ;

[0016] S23: The satellite terminal determines the relationship between the throughput estimate and the sensing time τ when the interleaving mode is used based on the worst sensing link signal-to-noise ratio estimate γ;

[0017] S24: The sensing time τ and the throughput estimate when the interleaving mode is used are determined with the objective of maximizing the throughput estimate ;

[0018] S25: The energy detection threshold ε of the satellite terminal when the interleaving mode is used is determined according to the sensing time τ.

[0019] Preferably, in the step S1, the position information of the satellite includes but is not limited to the orbital parameters of the satellite or the three-dimensional spatial coordinates of the satellite; and the position information of the ground communication system includes the position of the ground base station and the service range of the ground base station and / or the position of the ground terminal.

[0020] In the step S21, if the position information of the ground communication system obtained by the satellite terminal in the step S1 only includes the position and service range of the ground base station, the satellite terminal takes the position in the service range of the ground base station with the largest included angle with the main lobe of its receiving antenna as the reference point to determine the maximum off-axis angle θ ter between the main lobe of the receiving antenna of the satellite terminal and the ground terminal, and takes the position in the service range of the ground base station with the largest distance from it as the reference point to determine the maximum distance d ter between the satellite terminal and the ground terminal.

[0021] If the position information of the ground communication system acquired by the satellite terminal in step S1 includes the position of the ground terminal, the satellite terminal uses the position of the ground terminal with the largest angle between the main axis of its receiving antenna as a reference point to determine the maximum off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground terminal. ter The maximum distance d between the satellite terminal and the ground terminal is determined by taking the position of the ground terminal farthest from it as the reference point. ter .

[0022] Preferably, in step S22, the worst perceived link signal-to-noise ratio estimation value γ is:

[0023]

[0024] in, represents the transmitting antenna gain of the ground terminal, Indicates that the satellite terminal is at the maximum off-axis angle θ ter The receiving antenna gain in the direction of represents the transmission power of the ground terminal, represents the noise power when the satellite terminal performs spectrum sensing, represents the maximum path loss between the satellite terminal and the ground terminal, is the maximum distance d ter function;

[0025] In step S23, the throughput estimation value The relationship between it and the perception time τ is:

[0026]

[0027] Where T represents the frame duration, which includes the satellite terminal’s perception time and data transmission time; Q(·) is the complementary distribution function of the standard Gaussian distribution, Q -1 (·) is the inverse function of Q(·); represents the target detection probability; f s represents the carrier frequency of the shared frequency band; P1 represents the frequency band occupancy probability of the shared frequency band; C S It indicates the transmission capacity that can be achieved when a satellite terminal performs data transmission on a shared frequency band;

[0028] Preferably, in step S25, the energy detection threshold ε adopted by the satellite terminal is:

[0029]

[0030] Among them, σ 2 represents the variance of the satellite terminal noise, γ is the worst perception link signal-to-noise ratio estimate, τ is the perception time, Q(·) is the complementary distribution function of the standard Gaussian distribution, Q-1 (·) is the inverse function of Q(·); represents the target detection probability, f s Indicates the shared band carrier frequency.

[0031] Preferably, the step S3 specifically includes:

[0032] S31: The satellite terminal calculates the off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground base station based on the satellite position information and the ground base station position information. BS , and the distance d between the satellite terminal and the ground base station BS ;

[0033] S32: Based on the interference power threshold I th , determine the transmission power of the satellite terminal when using the overlapping mode To ensure that the interference power received by the ground base station is at most the interference power threshold I th ;

[0034] S33: Based on the transmit power of satellite terminals Determine the throughput estimate for the satellite terminal when using overlap mode.

[0035] Preferably, in step S32, the transmission power of the satellite terminal for:

[0036]

[0037] in, Indicates that the satellite terminal is at an angle θ BS Transmitting antenna gain in direction; Indicates the receiving antenna gain of the ground base station; Indicates the maximum transmit power of the satellite terminal; Indicates the path loss between the satellite terminal and the ground base station, the path loss between the satellite terminal and the ground base station is the distance d between the satellite terminal and the ground base station BS function;

[0038] Estimated throughput of satellite terminals using overlapping mode for:

[0039]

[0040] Where W represents the transmission bandwidth of the shared frequency band, T represents the frame duration, represents the peak gain of the satellite terminal transmitting antenna, represents the satellite receiving antenna gain, is the transmission power of the satellite terminal, is the noise power of the satellite, c is the speed of light, d S represents the distance between the satellite terminal and the satellite, f s Indicates the shared band carrier frequency.

[0041] Preferably, when the interleaving mode is selected, the satellite terminal uses the corresponding spectrum sensing parameters to perform spectrum sensing on the ground communication system and performs data transmission according to the spectrum sensing results; when the overlapping mode is selected, the satellite terminal uses the corresponding transmission power to perform data transmission.

[0042] Preferably, when selecting the interleaving mode, if the satellite terminal detects that the energy on the shared frequency band is less than or equal to the energy detection threshold within the perception time, the satellite terminal may perform uplink data transmission on the frequency band; otherwise, the satellite terminal suspends uplink data transmission on the frequency band.

[0043] Preferably, in step S1, the satellite terminal obtains the satellite's location information by receiving satellite broadcast signaling or querying the satellite ephemeris database; the satellite terminal obtains the ground communication system's location information by querying the database of the satellite-ground fusion network control center.

[0044] The uplink spectrum sharing method in the satellite-ground fusion network of the present invention is a method in which the satellite terminal selects a spectrum sharing mode based on the location information of the satellite and the ground communication system, and optimizes the spectrum sensing parameters or transmission power. Compared with a spectrum sharing scheme that only adopts a single mode, the transmission throughput of the satellite terminal is improved, while avoiding serious interference with the ground system, effectively improving the spectrum utilization efficiency of the satellite-ground fusion network. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic diagram of an uplink spectrum sharing scenario in a satellite-ground fusion network.

[0046] Figure 2 It is a flow chart of the uplink spectrum sharing method in the satellite-ground fusion network of the present invention. DETAILED DESCRIPTION

[0047] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process. However, the protection scope of the present invention is not limited to the following embodiment.

[0048] In response to the shortcomings of the existing technology, the present invention proposes an uplink spectrum sharing method in a satellite-ground fusion network. The satellite terminal selects a spectrum sharing mode according to the location information of the satellite and the ground system, and optimizes the spectrum sensing parameters or transmission power, thereby improving the transmission throughput of the satellite terminal while avoiding serious interference with the ground system, effectively improving the spectrum utilization efficiency of the satellite-ground fusion network.

[0049] The uplink spectrum sharing scenario in the satellite-ground fusion network considered by the present invention is as follows: Figure 1 As shown. Figure 1 As shown, the uplink spectrum sharing method in a satellite-ground integrated network of the present invention involves a terrestrial communication system 100 and a satellite communication system 200 using a shared frequency band for uplink transmission. The terrestrial communication system 100 is a primary system and includes a ground terminal 101 and a ground base station 102. The ground terminals are located at different locations within the service range of the ground base station. The uplink from the ground terminal 101 to the ground base station 102 is a primary user link. The satellite communication system 200 is a secondary system and includes a satellite terminal 201 and a satellite 202. The uplink from the satellite terminal 201 to the satellite 202 is a secondary user link. When the satellite terminal 201 uses the shared frequency band with the terrestrial communication system 100 for uplink transmission, if the interleaving mode is used, the satellite terminal 201 should use spectrum sensing technology to detect the transmission signal of the ground terminal 101; if the overlapping mode is used, the satellite terminal 201 should ensure that the interference power received by the ground base station 102 from the satellite terminal 201 is below the interference power threshold.

[0050] like Figure 2 As shown, the uplink spectrum sharing method in the satellite-ground integrated network of the present invention involves a terrestrial communication system 100 and a satellite communication system 200 using a shared frequency band for uplink transmission, and the specific steps are as follows:

[0051] Step S1: The satellite terminal 201 obtains the location information of the satellite 202 and the location information of the terrestrial communication system 100 sharing the frequency band;

[0052] The location information of the satellite 202 includes but is not limited to the orbital parameters of the satellite 202 (such as the six orbit numbers of the satellite 202 ) or the three-dimensional spatial coordinates of the satellite 202 .

[0053] The satellite terminal 201 may obtain the position information of the satellite 202 by receiving broadcast signaling from the satellite 202 or querying a satellite ephemeris database.

[0054] The location information of the ground communication system 100 should at least include the location of the ground base station 102 , and may also include the service range of the ground base station 102 , and / or the location of the ground terminal 101 .

[0055] The satellite terminal 201 can obtain the location information of the ground communication system 100 in the shared frequency band by querying the database of the satellite-ground fusion network control center. The satellite-ground fusion network control center can be set up on the ground.

[0056] The location and service range of ground base stations generally do not change, but the location of ground terminals may change. If the location information of the ground communication system 100 includes the location of the ground terminal, it needs to be acquired in real time. Otherwise, the location information of the ground communication system 100 only needs to be acquired once. For geosynchronous orbit satellites, the satellites are stationary relative to the ground, so frequent location acquisition is not required. For medium-orbit or low-orbit satellites, the satellites move at high speed relative to the ground, so the satellite location information needs to be updated in real time.

[0057] Step S2: The satellite terminal 201 determines the spectrum sensing parameters and throughput estimation value of the satellite terminal 201 when the interleaving mode is adopted based on the position information of the satellite 202 and the position information of the ground communication system 100.

[0058] Spectrum sensing parameters include but are not limited to sensing time and energy detection threshold.

[0059] The step S2 specifically includes:

[0060] Step S21: The satellite terminal 201 calculates the maximum off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground terminal based on the position information of the satellite 202 and the position information of the ground communication system 100. ter , and the maximum distance d between the satellite terminal and the ground terminal ter .

[0061] Among them, the maximum off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground terminal ter The orientation of the satellite's transmit or receive antenna is irrelevant, and only the orientation of the receive antenna of satellite terminal 201 is relevant. Satellite terminal 201 knows the orientation of its own receive antenna (usually continuously pointing toward the satellite), so based on the position information of the satellite and the ground communication system, satellite terminal 201 can determine the off-axis angle between the main axis of the satellite terminal's receive antenna and the ground terminal.

[0062] by Figure 1 For example, when the receiving antenna of satellite terminal 201 points to the satellite, the angle between the line connecting satellite terminal 201 and satellite 202 and the line connecting satellite terminal 201 and ground terminal 101 is the off-axis angle between the main axis of the satellite terminal receiving antenna and the ground terminal. When there may be multiple ground terminals, satellite terminal 201 needs to find the maximum off-axis angle θ among them. ter (See below for details).

[0063] The position coordinates of satellite terminal 201 are (x1, y1), the position coordinates of ground terminal 101 are (x2, y2), and the distance between the satellite terminal and the ground terminal is When there may be multiple ground terminals, the satellite terminal needs to find the maximum distance d between the satellite terminal and the ground terminal. ter (See below for details).

[0064] If the location information of the ground communication system 100 acquired by the satellite terminal 201 in step S1 only includes the location and service range of the ground base station 102, the satellite terminal 201 uses the location in the service range of the ground base station 102 where the angle between the main axis of its receiving antenna is the largest as a reference point to determine the maximum off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground terminal. ter The maximum distance d between the satellite terminal and the ground terminal is determined by taking the farthest position in the service range of the ground base station 102 as the reference point. ter .

[0065] If the position information of the ground communication system 100 acquired by the satellite terminal 201 in step S1 includes the position of the ground terminal 101, the satellite terminal 201 uses the position of the ground terminal with the largest angle between the main axis of its receiving antenna as a reference point to determine the maximum off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground terminal. ter The maximum distance d between the satellite terminal and the ground terminal is determined by taking the position of the ground terminal farthest from it as the reference point. ter .

[0066] Step S22: Based on the maximum off-axis angle θ ter and the maximum distance d ter , the satellite terminal determines the worst perceived link signal-to-noise ratio estimation value γ between the satellite terminal and the ground terminal;

[0067] The worst perceived link signal-to-noise ratio estimate γ can be expressed as:

[0068]

[0069] in, represents the transmitting antenna gain of the ground terminal, Indicates that the satellite terminal is at the maximum off-axis angle θ ter The receiving antenna gain in the direction of represents the transmission power of the ground terminal, represents the noise power when the satellite terminal performs spectrum sensing, represents the maximum path loss between the satellite terminal and the ground terminal, is the maximum distance d ter Functions in different scenarios The expressions are different.

[0070] The satellite terminal can obtain the noise power when performing spectrum sensing by using the noise estimation algorithm in existing literature. For example, [Y.Wang, X.Ding, J.Li, T.Hong and G.Zhang,"Blind Noise FloorEstimation aided Spectrum Sensing for Satellite Communication Systems,"2022International Symposium on Networks,Computers and Communications(ISNCC),Shenzhen,China,2022,pp.1-5]. The maximum path loss between the satellite terminal and the ground terminal Reference may be made to existing literature (eg, 3GPP Technical Report TR38.901) to obtain path loss models applicable to different scenarios.

[0071] Step S23: Determine the throughput estimate when using the interleaving mode based on the worst perceived link signal-to-noise ratio estimate γ The relationship between it and the perceived time τ;

[0072] Throughput estimates The relationship between it and the perception time τ can be expressed as:

[0073]

[0074] Where T represents the frame duration, which includes the satellite terminal’s perception time and data transmission time; Q(·) is the complementary distribution function of the standard Gaussian distribution, Q -1 (·) is the inverse function of Q(·); represents the target detection probability, which is predefined or configured by the control center; f s represents the carrier frequency of the shared frequency band; P1 represents the frequency band occupancy probability of the shared frequency band, which can be obtained by statistically analyzing the historical data of spectrum sensing results in the interleaved mode; C S It indicates the transmission capacity that can be achieved when a satellite terminal transmits data on a shared frequency band.

[0075] Historical spectrum sensing results are obtained as follows: In interleaved mode, the satellite terminal performs spectrum sensing in each frame. The spectrum sensing result indicates whether the frequency band is occupied (that is, the energy in the shared frequency band is greater than the energy detection threshold ε) or not occupied (that is, the energy in the shared frequency band is less than or equal to the energy detection threshold ε). The satellite terminal collects the spectrum sensing results for the shared frequency band over a period of time and obtains the frequency band occupancy probability P1 of the shared frequency band.

[0076] Step S24: Maximizing the throughput estimate For the goal, that is To determine the perception time τ and throughput estimation value when using the interleaving mode

[0077] The calculation method of the perception time τ can adopt the classic convex optimization algorithm.

[0078] Step S25: Determine the energy detection threshold ε of the satellite terminal when the interleaving mode is adopted according to the sensing time τ.

[0079] After determining the sensing time τ, the energy detection threshold ε used by the satellite terminal is:

[0080]

[0081] Among them, σ 2 represents the variance of the satellite terminal noise, γ is the worst perception link signal-to-noise ratio estimate, τ is the perception time, Q(·) is the complementary distribution function of the standard Gaussian distribution, Q -1 (·) is the inverse function of Q(·); represents the target detection probability, f s Indicates the shared band carrier frequency.

[0082] Therefore, through the above method, the satellite terminal can obtain the perception time τ, energy detection threshold ε and throughput estimation value when using the interleaving mode

[0083] Step S3: The satellite terminal 201 determines the transmission power and throughput estimation value of the satellite terminal 201 when the overlapping mode is adopted based on the position information of the satellite 202 and the position information of the ground communication system 100.

[0084] The step S3 specifically includes:

[0085] Step S31: The satellite terminal 201 calculates the off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground base station based on the position information of the satellite 202 and the position information of the ground base station. BS , and the distance d between the satellite terminal and the ground base station BS ;

[0086] Step S32: According to the interference power threshold I th , determine the transmission power of the satellite terminal when using the overlapping mode To ensure that the interference power received by the ground base station is at most the interference power threshold I th ;

[0087] In order to ensure that the interference power received by the ground base station is not greater than the interference power threshold I th , the satellite terminal's transmission power p t S for:

[0088]

[0089] in, Indicates that the satellite terminal is at an angle θ BS Transmitting antenna gain in direction; Indicates the receiving antenna gain of the ground base station; Indicates the maximum transmit power of the satellite terminal; Indicates the path loss between the satellite terminal and the ground base station, the path loss between the satellite terminal and the ground base station is the distance d between the satellite terminal and the ground base station BS Functions in different scenarios The expression of can be referred to existing literature.

[0090] Step S33: Based on the transmission power of the satellite terminal Determine the throughput estimate for the satellite terminal when using overlap mode.

[0091] Estimated throughput of satellite terminals using overlapping mode for:

[0092]

[0093] Where W represents the transmission bandwidth of the shared frequency band, T represents the frame duration, represents the peak gain of the satellite terminal transmitting antenna, represents the satellite receiving antenna gain, is the transmission power of the satellite terminal, is the noise power of the satellite, c is the speed of light, d S represents the distance between the satellite terminal and the satellite, f s Indicates the shared band carrier frequency.

[0094] Step S4: The satellite terminal 201 selects the one with the larger throughput estimation value from the two spectrum sharing modes, the interleaved mode and the overlapped mode, to perform uplink data transmission.

[0095] That is, the throughput estimate when using interleaved mode is Throughput estimates when using overlapping mode When , the satellite terminal selects the interleaving mode; when , the satellite terminal selects overlay mode.

[0096] Among them, when the interleaving mode is selected, the satellite terminal uses the corresponding spectrum sensing parameters to perform spectrum sensing on the ground communication system and performs data transmission according to the spectrum sensing results; when the overlapping mode is selected, the satellite terminal uses the corresponding transmission power for data transmission.

[0097] When selecting the interleaving mode, if the satellite terminal detects that the energy on the shared frequency band is less than or equal to the energy detection threshold ε within the sensing time τ, the satellite terminal can perform uplink data transmission on the frequency band; otherwise, the satellite terminal suspends uplink data transmission on the frequency band.

[0098] Different spectrum sharing modes require different amounts of data to be transmitted per frame. Therefore, the satellite terminal must pre-encapsulate, modulate, and encode the buffered data according to the different modes. If the overlap mode is temporarily switched because the energy in the shared frequency band within a frame exceeds the energy detection threshold, the satellite terminal must re-encapsulate, modulate, and encode the data. This introduces a certain delay and is therefore not recommended for practical systems.

[0099] In overlap mode, the satellite terminal uses transmit power Data transmission is performed to ensure that the interference power received by the ground base station from the satellite terminal is less than or equal to the interference power threshold I th .

[0100] The above descriptions are merely typical embodiments of the present invention and are not intended to limit the scope of the present invention. Various variations are possible in the above embodiments of the present invention. In other words, any simple, equivalent variations and modifications made in accordance with the claims and description of the present invention are within the scope of protection of the patent claims. Anything not fully described in this invention constitutes conventional technology.

Claims

1. A method for sharing uplink spectrum in a satellite-ground fusion network, involving a terrestrial communication system and a satellite communication system using a shared frequency band for uplink transmission, wherein the terrestrial communication system includes a ground terminal and a ground base station, and the satellite communication system includes a satellite terminal and a satellite, characterized in that: The uplink spectrum sharing method includes: Step S1: The satellite terminal obtains the location information of the satellite and the location information of the ground communication system sharing the frequency band; Step S2: The satellite terminal determines a spectrum sensing parameter and a throughput estimation value of the satellite terminal when the interleaving mode is adopted based on the satellite position information and the position information of the ground communication system; Step S3: The satellite terminal determines the estimated transmit power and throughput of the satellite terminal when the overlap mode is adopted based on the satellite position information and the position information of the ground communication system; Step S4: The satellite terminal selects a spectrum sharing mode with a larger throughput estimation value from the two spectrum sharing modes, the interleaved mode and the overlapped mode, to perform uplink data transmission.

2. The uplink spectrum sharing method in a satellite-ground fusion network according to claim 1, characterized in that: In step S2, the spectrum sensing parameters include sensing time and energy detection threshold.

3. The uplink spectrum sharing method in a satellite-ground fusion network according to claim 2, characterized in that: The step S2 specifically includes: Step S21: The satellite terminal calculates the maximum off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground terminal based on the satellite position information and the position information of the ground communication system. ter , and the maximum distance d between the satellite terminal and the ground terminal ter ; Step S22: Based on the maximum off-axis angle θ ter and the maximum distance d ter , the satellite terminal determines the worst perceived link signal-to-noise ratio estimation value γ between the satellite terminal and the ground terminal; Step S23: Determine the throughput estimate when using the interleaving mode based on the worst perceived link signal-to-noise ratio estimate γ The relationship between it and the perceived time τ; Step S24: Maximizing the throughput estimate For the goal, that is To determine the perception time τ and throughput estimation value when using the interleaving mode Step S25: Determine the energy detection threshold ε of the satellite terminal when the interleaving mode is adopted according to the sensing time τ.

4. The uplink spectrum sharing method in a satellite-ground fusion network according to claim 3, characterized in that: In step S1, the satellite location information includes but is not limited to the satellite's orbital parameters or the satellite's three-dimensional spatial coordinates; and the location information of the ground communication system includes the location of the ground base station, and the service range of the ground base station and / or the location of the ground terminal; In step S21, if the location information of the ground communication system obtained by the satellite terminal in step S1 only includes the location and service range of the ground base station, the satellite terminal uses the position in the service range of the ground base station with the largest angle with the main axis of its receiving antenna as a reference point to determine the maximum off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground terminal. ter The maximum distance d between the satellite terminal and the ground terminal is determined by taking the farthest position in the service range of the ground base station as the reference point. ter ; If the position information of the ground communication system acquired by the satellite terminal in step S1 includes the position of the ground terminal, the satellite terminal uses the position of the ground terminal with the largest angle between the main axis of its receiving antenna as a reference point to determine the maximum off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground terminal. ter The maximum distance d between the satellite terminal and the ground terminal is determined by taking the position of the ground terminal farthest from it as the reference point. ter .

5. The uplink spectrum sharing method in a satellite-ground fusion network according to claim 3, characterized in that: In step S22, the worst perceived link signal-to-noise ratio estimate γ is: in, represents the transmitting antenna gain of the ground terminal, Indicates that the satellite terminal is at the maximum off-axis angle θ ter The receiving antenna gain in the direction of represents the transmission power of the ground terminal, represents the noise power when the satellite terminal performs spectrum sensing, represents the maximum path loss between the satellite terminal and the ground terminal, is the maximum distance d ter function; In step S23, the throughput estimation value The relationship between it and the perception time τ is: Where T represents the frame duration, which includes the satellite terminal’s perception time and data transmission time; Q(·) is the complementary distribution function of the standard Gaussian distribution, Q -1 (·) is the inverse function of Q(·); represents the target detection probability; f s represents the carrier frequency of the shared frequency band; P1 represents the frequency band occupancy probability of the shared frequency band; C S It indicates the transmission capacity that can be achieved when a satellite terminal performs data transmission on a shared frequency band; In step S25, the energy detection threshold ε used by the satellite terminal is: Among them, σ 2 represents the variance of the satellite terminal noise, γ is the worst perception link signal-to-noise ratio estimate, τ is the perception time, Q(·) is the complementary distribution function of the standard Gaussian distribution, Q -1 (·) is the inverse function of Q(·); represents the target detection probability, f s Indicates the shared band carrier frequency.

6. The uplink spectrum sharing method in a satellite-ground fusion network according to claim 1, characterized in that: The step S3 specifically includes: Step S31: The satellite terminal calculates the off-axis angle θ between the main axis of the satellite terminal receiving antenna and the ground base station based on the satellite position information and the ground base station position information. BS , and the distance d between the satellite terminal and the ground base station BS ; Step S32: According to the interference power threshold I th , determine the transmission power of the satellite terminal when using the overlapping mode To ensure that the interference power received by the ground base station is at most the interference power threshold I th ; Step S33: Based on the transmission power of the satellite terminal Determine the throughput estimate for the satellite terminal when using overlap mode.

7. The uplink spectrum sharing method in a satellite-ground fusion network according to claim 6, characterized in that: In step S32, the transmission power of the satellite terminal for: in, Indicates that the satellite terminal is at an angle θ BS Transmitting antenna gain in direction; Indicates the receiving antenna gain of the ground base station; Indicates the maximum transmit power of the satellite terminal; Indicates the path loss between the satellite terminal and the ground base station, the path loss between the satellite terminal and the ground base station is the distance d between the satellite terminal and the ground base station BS function; Estimated throughput of satellite terminals using overlapping mode for: Where W represents the transmission bandwidth of the shared frequency band, T represents the frame duration, represents the peak gain of the satellite terminal transmitting antenna, represents the satellite receiving antenna gain, is the transmission power of the satellite terminal, is the noise power of the satellite, c is the speed of light, d S represents the distance between the satellite terminal and the satellite, f s Indicates the shared band carrier frequency.

8. The uplink spectrum sharing method in a satellite-ground fusion network according to claim 1, characterized in that: When the interleaving mode is selected, the satellite terminal uses the corresponding spectrum sensing parameters to perform spectrum sensing on the ground communication system and performs data transmission based on the spectrum sensing results; when the overlapping mode is selected, the satellite terminal uses the corresponding transmission power for data transmission.

9. The uplink spectrum sharing method in a satellite-ground fusion network according to claim 2, characterized in that: When selecting the interleaving mode, if the satellite terminal detects that the energy on the shared frequency band is less than or equal to the energy detection threshold within the sensing time, the satellite terminal may perform uplink data transmission on the frequency band; otherwise, the satellite terminal suspends uplink data transmission on the frequency band.

10. The uplink spectrum sharing method in a satellite-ground fusion network according to claim 1, characterized in that: In step S1, the satellite terminal obtains the satellite's location information by receiving satellite broadcast signaling or querying the satellite ephemeris database; the satellite terminal obtains the ground communication system's location information by querying the database of the satellite-ground fusion network control center.

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