CN107509203A - A frequency sharing method and system for a fusion satellite-ground system based on dynamic spectrum allocation - Google Patents

Abstract

The invention relates to the technical field of frequency sharing of a fusion satellite-ground system, in particular to a method and system for frequency sharing of a fusion satellite-ground system based on dynamic spectrum allocation. In order to solve the disadvantages that the frequency sharing technology of the existing fusion satellite-ground system needs to keep the density of active users relatively low, and has strong constraints on the fusion satellite-ground system, it proposes a fusion satellite-ground system based on dynamic spectrum allocation The system frequency sharing method and system, including: dividing the total frequency resources into 9 segments of frequency resources from F1 to F9; dividing the satellite beam into regions, and each divided region corresponds to one of the frequency resources from F1 to F9; according to The predetermined rule assigns each terrestrial cell one of the three groups of frequency ranges F1 to F3, F4 to F6, and F7 to F9, and randomly selects physical resource blocks that do not overlap each other in each group and allocates them to users. The invention is applicable to the fusion star-earth system.

Description

A frequency sharing method and system for a fusion satellite-ground system based on dynamic spectrum allocation

technical field

The invention relates to the technical field of frequency sharing of a fusion satellite-ground system, in particular to a method and system for frequency sharing of a fusion satellite-ground system based on dynamic spectrum allocation.

Background technique

With the development of the communication industry, users have higher and higher requirements on the quality and mode of communication. Users hope that they can use handheld terminals to complete high-quality communication no matter when and where. Although cellular mobile communication has good communication quality and its infrastructure has been completed, it is worth noting that more than 70% of the earth's area is covered by ocean deserts, and it is relatively difficult and costly to build base stations in these places. Satellite communication has the advantages of wide coverage and easier global coverage of communications. Then, integrating satellite communication with existing terrestrial cellular mobile communication to build a satellite-ground integrated network to give full play to the advantages of satellite communication and terrestrial cellular mobile communication is more conducive to achieving global coverage of communication.

The so-called "satellite-ground integrated system" has been used since the late 1980s, but it has become more perfect and meaningful with the evolution of the integrated system. ITU also gives the definition of satellite-earth integration, and at the same time, ITU distinguishes between the definitions of the fusion star-earth system and the hybrid star-earth system. Existing literature has done a detailed analysis of the two types of systems, from which we know that the main difference between the two systems is whether they operate in the same frequency band and whether they have the same network management center. The frequency sharing technology is adopted in the integrated satellite-ground system, which greatly improves the spectrum efficiency, improves the system capacity and simplifies the terminal equipment. However, an unavoidable problem in adopting the frequency sharing technology in the integrated satellite-ground network is that it will cause co-channel interference, which will seriously affect the communication quality of users. At present, many scholars have verified the feasibility of the frequency sharing technology of the integrated satellite-earth system, and adopted soft frequency reuse, partial frequency reuse and frequency reuse schemes based on protected areas to solve the interference problem. However, for soft frequency reuse and some frequencies, it is mainly to solve the interference problem between beams, while the frequency reuse scheme based on the protection zone has solved the interference between the satellite network and the ground network, and verified the feasibility. However, the frequency reuse schemes mentioned above are all static frequency assignments to keep the interference level within a tolerable range, but this requires keeping the active user density relatively low, which is a very strong constraint for the integrated satellite-ground system.

Contents of the invention

The purpose of the present invention is to solve the disadvantages that the existing frequency sharing technology of the fusion satellite-ground system needs to keep the density of active users relatively low, and has strong constraints on the fusion satellite-ground system, and proposes a dynamic spectrum allocation-based A frequency sharing method and system for a fusion satellite-earth system.

A frequency sharing method for a fusion satellite-earth system based on dynamic spectrum allocation, comprising:

Step 1. Dividing the total frequency resources into 9 segments of frequency resources from F1 to F9;

Step 2, divide the satellite beam into regions, and each divided region corresponds to one of the frequency resources from F1 to F9;

Step 3. The terrestrial cells covered by satellite beams use a 1/3 multiplexing scheme, specifically: allocate one of the three groups of frequency ranges F1 to F3, F4 to F6, and F7 to F9 for each terrestrial cell according to predetermined rules , randomly select non-repeating physical resource blocks in each group and assign them to users.

The beneficial effects of the present invention are: 1. There is no need to maintain a low active user density, and there is no strong constraint on the integrated satellite-ground system; 2. The present invention adopts different multiplexing schemes for the ground network and the satellite network, here On the basis of adopting the mode of dynamic frequency allocation to carry out frequency spectrum allocation, the interference is reduced; 3, the traditional frequency reuse scheme is a static scheme that only considers interference alone, and the present invention reduces interference by analyzing user characteristics, and the reduction of interference The effect is more obvious; 4. When there are 8 users in each ground cell, the interference-to-noise ratio of the frequency strategy based on user potential interference of the present invention can be as low as -13.5dB.

Description of drawings

Fig. 1 is the flowchart of the fusion satellite-earth system frequency sharing method based on dynamic spectrum allocation of the present invention;

Figure 2 Converged star-earth system architecture;

Figure 3 shows the interference scene of the integrated satellite-ground system;

Figure 4 is the seven-color multiplexing scheme of the fusion star-earth system;

Figure 5a) is the interference from the ground base station to the satellite terminal; b) is the interference from the satellite to the ground network terminal; c) is the interference from the satellite terminal to the base station; d) is the interference from the ground terminal to the satellite;

Fig. 6 is frequency resource division;

Fig. 7 is satellite beam frequency division;

Figure 8 is a terrestrial frequency reuse scheme;

Figure 9 is the frequency division of the 1/3 multiplexing scheme of the terrestrial network cell;

Fig. 10 shows the interference simulation results under the dynamic resource allocation scheme.

detailed description

Specific implementation mode one: the frequency sharing method of the integrated satellite-earth system based on dynamic spectrum allocation in this embodiment, as shown in Figure 1, includes:

Step 1: Divide the total frequency resources into 9 segments of frequency resources from F1 to F9.

Step 2: Divide areas for the satellite beams, and each divided area corresponds to one of the frequency resources F1 to F9.

Step 3. The terrestrial cells covered by satellite beams use a 1/3 multiplexing scheme, specifically: allocate one of the three groups of frequency ranges F1 to F3, F4 to F6, and F7 to F9 for each terrestrial cell according to predetermined rules , randomly select non-repeating physical resource blocks in each group and assign them to users.

The method of the present invention is based on the fusion of the satellite network and the ground network. The fusion of the satellite network and the ground network has various forms, and the fusion satellite-ground system model based on the ground auxiliary component (ATC) technology is one of many schemes. The ATC-based integrated satellite-earth system model is shown in Figure 2. The satellite gateway is connected with the base station of the ground cellular mobile communication through ground auxiliary component technology. The satellite part of the fusion satellite-earth system based on ATC technology adopts high-power and large-size antenna design, and at the same time, the introduction of large-aperture multi-beam technology is conducive to improving the effective isotropic radiated power (EIRP) earth station quality factor. At the same time, the various interface technologies used in the ground network are applicable to the ground and space stations, and the auxiliary components of different systems on the ground will run on a core cellular network.

The interference scenario model of the fused satellite-ground system is shown in Figure 3, and the model includes a satellite (SS), a ground base station (TBS) and a terminal (MS). For the convenience of analysis, the terminal is divided into ground terminal (TMS) and satellite terminal (SMS) here. At the same time, satellites, ground base stations, and terminals can communicate directly, so the solid line is a useful signal, and the dotted line is an interference signal. It can be seen that the satellite (SS) receives interference from the ground terminal (TMS). A unified multiplexing scheme is adopted in the entire integrated satellite-ground system, which is applicable to satellite beam cells and ground cellular cells. Figure 4 shows the seven-color frequency reuse scheme, that is, the cell cluster size is 7. In Fig. 4, the big circle represents the cell covered by the satellite beam, the several hexagons inside the big circle are the ground cell, and each color (or gray scale) represents a frequency band. According to the analysis, it is determined that the main interference in the fused satellite-ground system is the interference from the ground terminal to the satellite, as shown in Figures 5a)-5d).

For such interference, the present invention proposes a scheme based on dynamic resource allocation. The overall spectrum allocation is shown in Figure 6. The frequency resource of 15MHz is divided into 9 frequency resources of F1-F9 for the common use of the satellite network and the terrestrial network, and each frequency band is divided into 8 physical resource blocks. During the communication process, each user can be allocated 1 physical resource block for its use. In the simulation, in order to facilitate the allocation of frequency resources for each user, the physical resource blocks of the F1 to F9 frequency bands are numbered 1-72, which is the content of step 1.

The frequency multiplexing scheme adopted for the satellite network is shown in Figure 7. The satellite network adopts a 9-color multiplexing scheme, and each satellite beam can use 8 physical resource blocks. The satellite beam refers to the shape formed on the surface of the earth by the electromagnetic wave emitted by the satellite antenna (such as the beam emitted by a flashlight to a dark place), and its shape is determined by the transmitting antenna. There are cell clusters composed of 57 ground network cells in each satellite beam. The center of the cell cluster is randomly set. Each cell can have a maximum of 72 users, and the corresponding cell cluster can have a maximum of 4104 users. The frequency resources used by satellites are shown in Figure 7. In order to avoid interference between satellite network beams, adjacent satellite beams cannot use the same frequency band. F1-F9 represent the frequencies used by the satellite beams. That is the content of step two.

For ground cells, multiple schemes can be used to allocate frequencies to users in the ground cells. In the present invention, in order to obtain the effects of these two strategies on reducing interference, the strategy of randomly allocating frequencies to users is simulated at the same time. Figure 8 and Figure 9 are the frequency allocation diagrams of ground network cells under the 1/3 multiplexing scheme of the ground network. The same pattern in Figure 8 represents the same frequency, and (1), (2), and (3) in Figure 9 represent respectively The ground cell can use the frequency resources of F1-F3, F4-F6, and F7-F9.

It should be noted that the hexagonal area in Figure 9 is different from the hexagonal area in Figure 7. The hexagonal area in Figure 7 is the satellite cell in the satellite beam, that is, the area formed by satellite electromagnetic waves on the surface of the earth. shape, and the hexagon in Figure 9 is a ground cell, and the satellite cell may cover many ground cells. What frequency F1 to F9 in the hexagon among Fig. 7 represents is the frequency that satellite uses, take the first hexagon area 32 (2) as example in Fig. 9, and 32 represents that the serial number of this ground sub-district is 32, (2 ) indicates that it uses frequencies in the range of F4-F6, and when the total number of physical resource blocks is 72, the available physical resource block numbers corresponding to this frequency range are 25-48.

The purpose of step 3 is to select a frequency range for each ground cell, which is one of the three ranges of F1-F3, F4-F6, and F7-F9. There are various selection rules, After selection, which resource block in the frequency range is assigned to the user is random. For example, for the ground cell numbered 17, frequency resources F4-F6 are allocated to it according to the selected rules (corresponding to the (2)), and when the total number of physical resource blocks is 72, the resource block numbers of F4-F6 are 25-48, assuming that there are 8 users in the cell, then randomly select 8 from the resource blocks of 25-48 Resource blocks with different numbers are assigned to 8 users.

Specific implementation mode two: the difference between this implementation mode and specific implementation mode one is: in step two:

The division of satellite beams is as follows: determine the number of regions that can be divided according to the satellite parameters; allocate one of the frequency resources from F1 to F9 for each region, and ensure the sum of the distances of the regions where the same frequency resources are located during allocation higher than the preset value.

This embodiment is the process of allocating F1-F9 frequencies to each satellite cell in Figure 7. The principle of allocation is to make the physical distance of the same frequency as far as possible. are separated by at least two satellite cells. In actual operation, the sum of the distances in the same frequency area can be calculated. If the sum of the distances is the largest, the isolation is considered to be the largest. It can also be allocated through artificial settings or calculation of variance. The advantage of this setting is that it can reduce interference as much as possible.

Other steps and parameters are the same as those in Embodiment 1.

Embodiment 3: This embodiment differs from Embodiment 1 or Embodiment 2 in that: in step 3, the predetermined rule is a random selection rule. That is, when one of the three frequency ranges is selected for the ground cell, random selection is adopted.

In this principle, the satellite and ground parts are uncoordinated, and the resources in the ground system are allocated randomly according to the allocation pattern established in the ground system, regardless of the cell location or ground user conditions in the satellite frequency pattern. The terrestrial network cell adopts 1/3 color multiplexing, and randomly allocates available frequencies to users in the cell in the terrestrial network. As can be seen in Figure 9, the terrestrial network cell numbered 17 can use the frequency resources of F4-F6 (physical resource block numbers are 25-48). If there are 8 users in each cell, then any The 8 physical resource blocks with non-duplicate numbers are allocated to the 8 users.

The advantage of this setting is that the execution efficiency is relatively high and no complicated calculations are involved.

Other steps and parameters are the same as those in Embodiment 1 or Embodiment 2.

Embodiment 4: This embodiment differs from Embodiment 1 to Embodiment 3 in that: in step 3, the predetermined rule is: select the frequency resource with the highest degree of isolation relative to the location of the user; The sum of the distances from the location to the centers of all satellite cells of the same frequency; the satellite cell of the same frequency refers to the area after the division of the satellite beam, and the area where the ground cell where the user is located uses the same frequency.

Since the satellite cell is a part of the satellite beam, it is the projection of electromagnetic waves on the ground, and the ground cell is an area divided on the ground, so the location of the user can be in the satellite cell and the ground cell at the same time. The isolation calculated in this embodiment is the sum of the distances from the geographic location of the user to the centers of all co-frequency satellite cells. In the specific calculation, first assume that the user uses the F1 frequency, and then calculate the sum of the distances between the user's current position and the center of all F1 satellite cells with the same frequency in this case, where the center refers to the geometric center; then calculate F2, F3, etc. For the isolation of other frequencies, after calculating all the isolations, select the frequency resource with the highest isolation, and then allocate the corresponding frequency range for the ground cell.

This principle corresponds to the concept based on the protection area, the frequency allocation of terrestrial cells will depend on the location of the cells isolated under each beam in the satellite frequency pattern, and then allocate frequencies according to their maximum possible isolation from the satellite. This principle is the first level of coordination with the satellite. The terrestrial network cell adopts 1/3 multiplexing, and allocates the available frequency resource with the highest isolation degree to the user according to the location of the user. For example, users in the terrestrial network cell numbered 17 can only be allocated frequency resources with the highest isolation degree among F4-F6 (physical resource blocks numbered 25-48).

Other steps and parameters are the same as those in Embodiments 1 to 3.

Specific implementation mode five: the difference between this implementation mode and one of specific implementation modes one to four is:

In step 3, the predetermined selection rules are:

The interference power is calculated for the users of each terrestrial cell, and the calculation formula is:

IPP(e _l ) _dB ＝EIRP(e _l ) _dB -PL _sat (e _l ) _dB

＝I _sat (e _l ) _dB -G _rx,sat (e _l ) _dB

Among them, IPP(e _l ) _dB is the interference power of user e _l in the ground cell; EIRP(e _l ) _dB is the transmit power gain, PL _sat (e _l ) _dB is the path loss; I _sat (e _l ) _dB is the interference value ; G _rx,sat (e _l ) _dB is the gain value.

Then both the interference power and the isolation degree of the users are sorted, and according to the order of the interference power, the frequency of the isolation degree corresponding to the order is allocated to the user.

This principle goes a step further than the fourth embodiment, in the same manner as the frequency allocation strategy based on the location of the base station, the frequencies are sorted according to the order of isolation from the satellite. Users with the most satellite interference) are assigned frequencies with the least interference, and vice versa. To this end, we define a new parameter: potential interference power. The higher the potential interference power, the more serious the user interference. At the time of resource allocation, the interference power (IPP) is evaluated for all users. Users with higher IPP are then assigned the frequency with the best isolation.

This parameter denoted IPP is specific to each terrestrial user e _l . Its formula is as follows:

IPP(e _l ) _dB ＝EIRP(e _l ) _dB -PL _sat (e _l ) _dB

＝I _sat (e _l ) _dB -G _rx,sat (e _l ) _dB

It corresponds to the power of the interference transmitted by the user and received by the satellite at its antenna. It is a function of user-related factors: EIRP and propagation loss (of path loss) of the satellite. For path loss, the direct loss of propagation in free space is considered independent of the user. However, the satellite-only masking factor is user-dependent. Alternatively, IPP is the received interference power minus the satellite antenna gain.

In the allocation algorithm of the base station, channels are allocated according to the IPP of each user. We know the path loss for each user, but not the EIRP at the time of allocation. In fact, when we apply power control, it depends on the channel allocated to the user. Therefore, this allocation is based on an estimate of IPP based on an estimate of EIRP given in the formula below.

EIRP _est (e _l ) _dB ＝f(PL _ter (e _l ) _dB ,G _rx,BS (e _l ) _dB )

The estimated EIRP corresponds to the user's EIRP calculated in open loop such that the latter achieves the desired signal-to-noise ratio. It is a function of the path loss between the base station and the user and the antenna gain of the base station in the direction of the user.

That is, the terrestrial network cell adopts 1/3 multiplexing, detects the location of the user and the potential interference of the user, and assigns the frequency with the highest isolation to the user with the largest potential interference in the available frequency resources of the cell.

Other steps and parameters are the same as in one of the specific embodiments 1 to 4.

Specific Embodiment Six: This embodiment provides a frequency sharing system based on dynamic spectrum allocation for a fusion satellite-ground system, as shown in Figures 2 and 3, including satellites, ground base stations, ground terminals, satellite terminals, and gateways, wherein satellites, The ground base station, ground terminal, and satellite terminal can communicate directly, and the gateway is connected to the ground base station; the carrier frequency is 2GHz, the bandwidth is 15MHz, the number of physical resource blocks is 72, the satellite antenna is a GEO multi-beam satellite antenna, and the satellite channel model is Perez- In the Fontan model, the diameter of the satellite beam is 200km, the latitude of the ground cell cluster is 45 degrees, the coverage radius of the ground cell is 1/3km, the antenna gain of the ground base station is 20dB, the maximum power of the ground terminal and satellite terminal is 24Bm, and the minimum power is -30Bm. The terrestrial channel model is WINNER II; the total frequency resources are divided into F1 to F9 frequency bands; each satellite beam has a cell cluster composed of 57 terrestrial network cells, the center of the cell cluster is randomly set, and each cell has at most 72 user.

The satellite terminal is used to divide the satellite beams into regions, and each divided region corresponds to one of the frequency resources F1 to F9.

The ground terminal is used to allocate one of the three groups of frequency ranges F1 to F3, F4 to F6, and F7 to F9 for each ground cell according to predetermined rules, and randomly select non-repeating physical resource blocks in each group to allocate to users .

Embodiment 7. The difference between this embodiment and Embodiment 6 is that: the satellite terminal is specifically used to determine the number of regions that can be divided according to the satellite parameters; assign one of the frequency resources in F1 to F9 for each region, During allocation, it is ensured that the sum of distances of areas where the same frequency resources are located is higher than a preset value.

This embodiment is similar to the second embodiment, and the satellite terminal in this embodiment is used to implement the functions in the second embodiment, which will not be described in detail here.

Other steps and parameters are the same as those in Embodiment 6.

Embodiment 8. This embodiment is different from Embodiment 6 or 7 in that: in the ground terminal, the predetermined rule is a random selection rule.

This embodiment is similar to the third embodiment, and the ground terminal in this embodiment is used to implement the functions in the third embodiment, which will not be described in detail here.

Other steps and parameters are the same as those in Embodiment 6 or 7.

Specific embodiment nine, the difference between this embodiment and one of specific embodiment six to eight is:

In the ground terminal, the predetermined rule is: select the physical resource block with the largest isolation degree relative to the user's position in each group; the isolation degree is the sum of the distances from the user's position in the ground cell to the centers of all satellite cells of the same frequency; The same-frequency satellite cell refers to the area where the same frequency is selected as the ground cell where the user is located in the area after the satellite beam is divided.

This embodiment is similar to Embodiment 4, and the ground terminal in this embodiment is used to implement the functions in Embodiment 4, which will not be described in detail here.

Other steps and parameters are the same as those in Embodiment 6 to Embodiment 8.

Specific Embodiments Ten. The difference between this embodiment and one of the specific embodiments six to nine is that:

In the ground terminal, the predetermined rules are:

The interference power is calculated for the users of each terrestrial cell, and the calculation formula is:

IPP(e _l ) _dB ＝EIRP(e _l ) _dB -PL _sat (e _l ) _dB

＝I _sat (e _l ) _dB -G _rx,sat (e _l ) _dB

Among them, IPP(e _l ) _dB is the interference power of user e _l in the ground cell; EIRP(e _l ) _dB is the transmit power gain, PL _sat (e _l ) _dB is the path loss; I _sat (e _l ) _dB is the interference value ; G _rx,sat (e _l ) _dB is the gain value;

Both the interference power and the isolation degree of the users are sorted, and according to the order of the interference power, the frequency of the isolation degree corresponding to the order is allocated to the user.

This embodiment is similar to the fifth embodiment, and the ground terminal in this embodiment is used to implement the functions in the fifth embodiment, and will not be described in detail here.

Other steps and parameters are the same as one of the sixth to ninth specific embodiments.

<Example>

Carry out the simulation according to the specific implementation method, and the simulation parameters in the simulation process are set as follows: the carrier frequency is 2GHz, the bandwidth is 15MHz, the number of physical resource blocks is 72, the satellite antenna is a GEO multi-beam satellite antenna, and the satellite channel model is a Perez-Fontan model. The diameter of the satellite beam is 200km, the latitude of the ground cell cluster is 45 degrees, the coverage radius of the ground cell is 1/3km, and the antenna gain of the ground base station is The minimum/maximum power of the terminal is -30/24dBm, and the terrestrial channel model is WINNER II (C2).

The simulation environment is: matlab R2016a

The simulation results are shown in Fig. 5 and Fig. 10 , where the allocation of 1/3 multiplexing according to the location of the base station and the allocation of 1/3 multiplexing according to the content shown in Fig. 10 are the content of the invention.

When the ground network cell adopts the 1/3 frequency reuse scheme, the maximum number of users in each cell is 24. It can be seen that the frequency strategy based on the user's potential interference that allocates frequencies to users has the least interference on satellites, and the random frequency allocation strategy has the largest interference. The interference power increases with the number of users in the terrestrial network cell. In Figure 10, when the number of users is 8, the frequency allocation strategy based on the location of the base station and the frequency strategy scheme based on the potential interference of users have the same amount of interference on the satellite beam. This is because if the number of users in each cell is 8, only when the frequency with the highest isolation degree of a certain cell is the F1 frequency band, the 8 PRB frequency resources of F1 will be allocated to a user in the cell. In this case, regardless of whether the potential interference of users in the cell to the satellite is large or small, these 8 users will be allocated frequency resources of F1. Therefore, when the number of users is 8, the frequency allocation strategy based on the location of the base station and the frequency strategy based on the user's potential interference cause the same interference to the satellite. It can be seen that the proposed strategy reduces the interference to an allowable range, and the frequency allocation strategy based on the location of the base station and the frequency strategy based on the user's potential interference further reduce the interference.

The present invention can also have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations are all Should belong to the scope of protection of the appended claims of the present invention.

Claims (10)

1. A fusion satellite-earth system frequency sharing method based on dynamic spectrum allocation, characterized in that it comprises: Step 1. Dividing the total frequency resources into 9 segments of frequency resources from F1 to F9; Step 2, divide the satellite beam into regions, and each divided region corresponds to one of the frequency resources from F1 to F9; Step 3. The terrestrial cells covered by satellite beams use a 1/3 multiplexing scheme, specifically: allocate one of the three groups of frequency ranges F1 to F3, F4 to F6, and F7 to F9 for each terrestrial cell according to predetermined rules , randomly select non-repeating physical resource blocks in each group and assign them to users. 2. the fusion satellite-earth system frequency sharing method based on dynamic spectrum allocation according to claim 1, is characterized in that, in step 2: The division of satellite beams is as follows: determine the number of regions that can be divided according to the satellite parameters; allocate one of the frequency resources from F1 to F9 for each region, and ensure the sum of the distances of the regions where the same frequency resources are located during allocation higher than the preset value. 3. The frequency sharing method of the integrated satellite-earth system based on dynamic spectrum allocation according to claim 1, characterized in that, in step 3, the predetermined rule is a random selection rule. 4. the fusion satellite-earth system frequency sharing method based on dynamic spectrum allocation according to claim 1, is characterized in that, in step 3, described predetermined rule is: select the frequency resource that is maximum with respect to user position isolation degree; It is the sum of the distances from the location of the user in the ground cell to the centers of all satellite cells of the same frequency; the satellite cell of the same frequency is the area where the same frequency as the ground cell where the user is located is selected in the area after the satellite beam is divided. 5. the fusion satellite-earth system frequency sharing method based on dynamic spectrum allocation according to claim 1, is characterized in that, in step 3, described predetermined selection rule is: The interference power is calculated for the users of each terrestrial cell, and the calculation formula is: IPP(e _l ) _dB ＝EIRP(e _l ) _dB -PL _sat (e _l ) _dB ＝I _sat (e _l ) _dB -G _rx,sat (e _l ) _dB Among them, IPP(e _l ) _dB is the interference power of user e _l in the ground cell; EIRP(e _l ) _dB is the transmit power gain, PL _sat (e _l ) _dB is the path loss; I _sat (e _l ) _dB is the interference value ; G _rx,sat (e _l ) _dB is the gain value; Both the interference power and the isolation degree of the users are sorted, and according to the order of the interference power, the frequency of the isolation degree corresponding to the order is allocated to the user. 6. A fusion satellite-ground system frequency sharing system based on dynamic spectrum allocation, characterized in that it includes satellites, ground base stations, ground terminals, satellite terminals and gateways, wherein satellites, ground base stations, ground terminals, and satellite terminals can communicate directly , the gateway is connected to the ground base station; the carrier frequency is 2GHz, the bandwidth is 15MHz, the number of physical resource blocks is 72, the satellite antenna is a GEO multi-beam satellite antenna, the satellite channel model is the Perez-Fontan model, the satellite beam diameter is 200km, and the ground cell cluster The latitude is 45 degrees, the coverage radius of the ground cell is 1/3km, the antenna gain of the ground base station is 20dB, the maximum power of the ground terminal and satellite terminal is 24Bm, the minimum power is -30Bm, the ground channel model is WINNER II; the total frequency resources are divided into It is the F1 to F9 frequency band; each satellite beam has a cell cluster composed of 57 ground network cells, the center of the cell cluster is randomly set, and each cell has at most 72 users; The satellite terminal is used to divide the satellite beam into areas, and each divided area corresponds to one of the frequency resources from F1 to F9; The ground terminal is used to allocate one of the three groups of frequency ranges F1 to F3, F4 to F6, and F7 to F9 for each ground cell according to predetermined rules, and randomly select non-repeating physical resource blocks in each group to allocate to users . 7. The frequency sharing method of the integrated satellite-earth system based on dynamic spectrum allocation according to claim 6, wherein the satellite terminal is specifically used to determine the number of regions that can be divided according to the satellite parameters; assign F1 to F9 for each region One of the frequency resources in , the allocation ensures that the sum of the distances of the areas where the same frequency resources are located is higher than the preset value. 8. The frequency sharing method of the integrated satellite-ground system based on dynamic spectrum allocation according to claim 6, wherein, in the ground terminal, the predetermined rule is a random selection rule. 9. The frequency sharing method of the integrated satellite-ground system based on dynamic spectrum allocation according to claim 6, wherein, in the ground terminal, the predetermined rule is: in each group, select the physical resource with the largest degree of isolation relative to the user position block; the isolation is the sum of the distances from the user's location on the ground cell to the centers of all satellite cells of the same frequency; the satellite cell of the same frequency is the same frequency as the ground cell where the user is located in the area after the satellite beam is divided. area. 10. The frequency sharing method of the integrated satellite-ground system based on dynamic spectrum allocation according to claim 6, wherein, in the ground terminal, the predetermined rule is: The interference power is calculated for the users of each terrestrial cell, and the calculation formula is: IPP(e _l ) _dB ＝EIRP(e _l ) _dB -PL _sat (e _l ) _dB ＝I _sat (e _l ) _dB -G _rx,sat (e _l ) _dB Among them, IPP(e _l ) _dB is the interference power of user e _l in the ground cell; EIRP(e _l ) _dB is the transmit power gain, PL _sat (e _l ) _dB is the path loss; I _sat (e _l ) _dB is the interference value ; G _rx,sat (e _l ) _dB is the gain value; Both the interference power and the isolation degree of the users are sorted, and according to the order of the interference power, the frequency of the isolation degree corresponding to the order is allocated to the user.