Communication method suitable for complex scene of adjacent space

Abstract

The invention relates to a communication method suitable for an adjacent space complex scene. A communication system combining two working modes of one-to-many communication and point-to-point communication is adopted for adjacent space communication. In an adjacent space one-to-many communication scene, a single spacecraft is set as A, a plurality of spacecrafts are set as B1, B2,..., Bn, the signal-to-noise ratio of a received signal is improved at an A end by adopting a sliding window related joint maximum ratio combination method, and meanwhile, the signal-to-noise ratio of the received signal is improved at a Bi end by adopting an RAKE receiving joint maximum ratio combination method; a and Bi are respectively designed with a bandwidth adaptive working mode and a power adaptive working mode, and a corresponding working mode is selected according to scene requirements; and realizing large-scale spacecraft adjacent space communication by adopting an ad hoc network adjacent space communication method based on resource balance. According to the invention, the requirement of simultaneous communication between a single spacecraft and multiple spacecrafts is met, the problems of near-far effect and multipath effect are solved, and the power and bandwidth utilization rate of adjacent space communication and the system reliability are improved.

Description

Technical Field

[0001] The present invention belongs to the field of spacecraft measurement, control and communication, and relates to a communication method suitable for complex scenes in adjacent space. Background Art

[0002] With the development of aerospace technology and the expansion of business areas, flight missions involving the coordinated work of multiple spacecraft in adjacent space have begun to appear, such as the rendezvous and docking missions of manned space projects, deep space exploration missions, and constellation cluster flight missions. In the above missions, it is impossible to complete the work quickly and autonomously by relying solely on the interactive communication between the ground station and each spacecraft. It is necessary to adopt a communication method suitable for adjacent space to achieve autonomous interactive communication and coordinated autonomous work between each spacecraft in adjacent space.

[0003] The existing adjacent space communication methods realize time-division multiplexing point-to-point communication, but lack design considerations for complex scenarios in adjacent space. With the complexity of adjacent space missions, there is a need for multiple tracking spacecraft to communicate with the same target aircraft at the same time. If the point-to-point communication mode is still used, the following problems will arise: First, different tracking aircraft generally use the same communication system, that is, the same frequency, bandwidth, modulation and coding method, which can only guarantee the communication between one spacecraft and another at the same time, and cannot support one-to-many communication scenarios. Second, due to the different relative distances between different tracking aircraft and target aircraft, the energy of the power signals emitted by different tracking aircraft to reach the target aircraft is different, and the target aircraft receives abnormal signals due to the influence of the near-far effect. Third, with the increase in the number of spacecraft in the adjacent space and the increase in the size and complexity of the spacecraft configuration, such as the large-scale configuration of the spacecraft assembly and the large-scale solar panels, the multipath effect will inevitably occur, and as a result, the spacecraft receiving the signal cannot correctly demodulate the received data. Fourth, in the existing point-to-point communication mode, the transmission power of the spacecraft is generally a fixed value or a small number of adjustable fixed gears. Although the fixed communication system can ensure the establishment of links within the adjacent space range, it has the disadvantages of low power and bandwidth utilization. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to propose a communication method suitable for complex scenarios in adjacent space, to meet the needs of simultaneous communication between a single spacecraft and multiple spacecraft in adjacent space, and to solve the problem of near-far effect caused thereby, and to solve the problem of multipath effect caused by the complex configuration of large spacecraft, and finally to improve the power and bandwidth utilization of adjacent space communications and the system reliability through the method of software radio.

[0005] The solution of the present invention is:

[0006] A communication method applicable to complex scenes in adjacent spaces, comprising:

[0007] The adjacent space communication adopts a communication system that combines two working modes: one-to-many communication and point-to-point communication.

[0008] It is stipulated that in the one-to-many communication scenario in adjacent space, the transmission direction from a single spacecraft to multiple spacecraft is the forward direction, and the transmission direction from multiple spacecraft to a single spacecraft is the return direction. The forward and return links adopt the one-to-many communication working mode by default. If there is a temporary high-bandwidth transmission demand, the working mode will be switched to the point-to-point communication mode. After completing the high-bandwidth data transmission task, the one-to-many communication working mode will be restored.

[0009] In the one-to-many communication scenario in adjacent space, let the single spacecraft be A and the multiple spacecraft be B1, B2, …, B n At the A end, a sliding window-based joint maximum ratio combining method is used to improve the signal-to-noise ratio of the received signal. i The end uses the RAKE receiving joint maximum ratio combining method to improve the signal-to-noise ratio of the received signal, i=1,…,n,n≥1;

[0010] A and B i Design two working modes: bandwidth adaptation and power adaptation, and select the corresponding working mode according to the scenario requirements;

[0011] According to the above design, large-scale spacecraft adjacent space communication is realized by the self-organizing network adjacent space communication method based on resource balancing.

[0012] Preferably, the one-to-many communication working mode adopts a code division multiple access communication system, allocates different spread spectrum codes to different spacecraft, and maintains a suitable distance between codes. The spread spectrum code rate is determined according to the effective data bandwidth, transmission bandwidth and spread spectrum ratio requirements.

[0013] Preferably, the point-to-point communication working mode adopts a time division multiplexing communication system to divide the working time slices for different spacecraft. Only two spacecraft communicate with each other in the same time slice. A non-spread spectrum system is adopted, and all the transmission bandwidth is used to transmit valid data.

[0014] Preferably, the forward return link adopts an automatic power control method that resists near-far effect, and the specific implementation method is as follows:

[0015] a) A adopts a constant power design, and the transmission power is P At ; B1, B2, …, B n The transmission power is P Bt1 , P Bt2 ,…,P Btn , and B1, B2, …, B n Transmit power adjustable, B1, B2, ..., Bn According to the received power signal P of A Br1 , P Br2 ,…,P Brn Complete channel evaluation and calculate A to B1, B2, ..., B respectively. n The channel transmission loss L1, L2, ..., L n ;

[0016] b) According to the requirements of the adjacent space communication scenario, the optimal receiving power of A is specified as P Ar , according to the channel evaluation result of step a), set B1, B2, ..., B n The transmission power P Bt1 , P Bt2 ,…,P Btn , where P Bti =P Ar +L i +M, i=1,…,n, n≥1, M is the reserved margin, and the initial value is 0;

[0017] c) If A successfully receives B i The transmission signal is then replied to B i The access is successful. If it fails, B i Increase P by 3dB. Bti , until A successfully receives B i The transmitting signal and the access success message are sent;

[0018] d) After the return link is established, A and B i Business data interaction begins. A periodically collects statistics on the bit error rate P of business data. e , calculate the theoretical value of the signal-to-noise ratio Eb / N0 required to complete the normal business data transmission T , the statistical period is T;

[0019] e) Within the statistical period T, A actually measures the channel and obtains B i The actual measured value of the signal-to-noise ratio of the return link is Eb / N0 Ri , and Eb / N0 Ri and Eb / N0 T Compare and feed back the comparison result to B via message i , B i According to the news, P Bti Dynamically adjust in a step-by-step manner with a step length of 1dB to make Eb / N0 Ri Track and get close to Eb / N0 T , ultimately achieving the goal of equal power of each signal received by A and eliminating the near-far effect.

[0020] Preferably, Li =P At -P Bri ,i=1,…,n,n≥1.

[0021] Preferably, a sliding window correlation combined maximum ratio combining method is used at the A end to improve the signal-to-noise ratio of the received signal, and at the B end i The end uses the RAKE receiving joint maximum ratio combining method to improve the signal-to-noise ratio of the received signal and realize anti-multipath communication. The specific implementation method is as follows:

[0022] a) Using MIMO, m pairs of transceiver antennas are installed at equal intervals around the wall of A, B i Only one transceiver antenna is installed on the bulkhead, m≥3;

[0023] b) User B of A's internal storage i The return synchronization PN code, that is, PN i , receiving B through m antennas respectively i Return signal; i=1,…,n,n≥1;

[0024] c) For each antenna receiving user B i The return signal, A uses the internally stored PN code PN i Perform sliding window correlation to obtain the peak value;

[0025] d) A receives user B from all antennas i The data is combined with the maximum ratio according to the peak value obtained by sliding window correlation to obtain the highest signal-to-noise ratio, thus completing the return link data reception;

[0026] e) A sends forward signals through m antennas in time division, with a sending time interval of t;

[0027] f)B i The Rake receiver design is adopted, and the PN code of A stored internally is used to perform sliding window correlation on the received forward signal to obtain the peak value. By utilizing the property of A's multi-antenna staggered transmission, another two peak values ​​are found in the time slots t before and after the first peak value is obtained, and finally the multipath signals are separated for despreading and merging.

[0028] Preferably, A and B i , i=1,…,n,n≥1, respectively design bandwidth adaptive and power adaptive working modes, and select the corresponding working mode according to the scene requirements. The specific steps are as follows:

[0029] a) For scenarios that prioritize the energy constraints of spacecraft, select the power adaptive working mode:

[0030] A and B iThe signal-to-noise ratio of the received signal is evaluated respectively, and compared with the threshold signal-to-noise ratio of the receiving demodulation, and the link margin is calculated. Under the premise of ensuring the minimum link margin of 3dB, A and B i According to the link margin, the transmission power can be appropriately reduced to improve the energy efficiency of the spacecraft;

[0031] b) For scenarios where transmission bandwidth utilization is a priority, select the bandwidth adaptive working mode:

[0032] A and Bi evaluate the signal-to-noise ratio of the received signal respectively, and compare it with the threshold signal-to-noise ratio of the receiving demodulation to calculate the link margin; set the decision threshold of the receiver C / N0 to J1, J2…Ju;

[0033] Let the initial value of w be 1 and perform the following steps:

[0034] b1) If Jw≤C / N0≤Jw+1, then the decision threshold of C / N0 = Jw, otherwise go to b2);

[0035] b2) Determine whether w is u-1. If not, add 1 to the value of w and repeat b1); if w = u-1, the decision threshold of C / N0 = Jw, and the process ends;

[0036] Update the transmission bandwidth B and modulation mode according to the decision threshold of C / N0 to maintain the link margin M at 3dB;

[0037] c) By means of software radio, the modulation and demodulation working modes are switched according to the current link margin and the threshold signal-to-noise ratio of different demodulation modes.

[0038] Preferably, the method for communicating in adjacent spaces in a self-organizing network based on resource balancing comprises the following specific steps:

[0039] a) First, all spacecraft in the adjacent space communication scenario are numbered as: S1, S2, ..., Sq, q ≥ 3; S1, S2, ..., Sq are respectively equipped with relative positioning devices, and the relative distances between them are measured by the relative positioning devices;

[0040] b) S1, S2, ..., Sq calculate the relative distance measurement results respectively, and cluster the spacecraft according to the relative distance measurement results. The clustering method is as follows:

[0041] Set the distance threshold to Ds, and divide the spacecraft whose relative distance measurement results are less than or equal to Ds into the same cluster. Divide all spacecraft in the adjacent space into p clusters: C1, C2, ..., Cp, p≤q;

[0042] c) The spacecraft in each cluster are divided into two categories according to their different working roles, namely cluster head spacecraft and ordinary spacecraft. The ordinary spacecraft stores the number information and location information of the cluster head spacecraft. When there is a need for data transmission, the measured value dm of the relative distance to the cluster head spacecraft is calculated. According to the comparison result of dm and the forwarding distance threshold dt, if dm≤dt, the data is directly transmitted to the cluster head spacecraft, otherwise, it is forwarded to the cluster head spacecraft through the intermediate spacecraft, that is, other ordinary spacecraft; the cluster head spacecraft summarizes the data information of all spacecraft in the cluster, and determines whether the target spacecraft is in the cluster according to the number information of the target spacecraft contained in the data information. If it is in the cluster, the measured value dn of the relative distance between the target spacecraft and the cluster head spacecraft is calculated and compared with the forwarding distance threshold dt. If dn≤dt, the data is directly forwarded to the target spacecraft, otherwise, it is forwarded to the target spacecraft through the intermediate spacecraft;

[0043] If it is not in the cluster, it is transmitted to the cluster head spacecraft of the cluster where the target spacecraft is located. Finally, according to the measured value dn' of the relative distance between the target spacecraft and the cluster head spacecraft of its cluster, if dn'≤dt, the data is directly forwarded to the target spacecraft, otherwise, it is forwarded to the target spacecraft through the intermediate spacecraft;

[0044] d) Regularly evaluate the resources of each spacecraft in the cluster so that the spacecraft with the most resources can serve as the cluster head spacecraft, that is, dynamically generate a new cluster head spacecraft regularly;

[0045] The method for generating cluster head spacecraft is as follows:

[0046] d1) Calculate the current remaining battery energy, the power generation capacity of the solar panels and the current workload of each spacecraft in the cluster in real time, and obtain the comprehensive energy Ej of the spacecraft Sj, Ej = Xj + Fj - Pj * T', where Xj is the remaining battery energy, Fj is the power generation of the solar panels, Pj is the current load power of the spacecraft, T' is the working cycle, j = 1, 2, ..., p, j ≤ p; compare the comprehensive energy of each spacecraft, obtain the spacecraft with the most abundant comprehensive energy in the current evaluation cycle, and give the comprehensive energy resource ranking of all spacecraft in the cluster;

[0047] d2) Calculate the RF channel resources and occupancy of each spacecraft in the cluster in real time, find the spacecraft with the best channel resources in the current evaluation period, and give the channel resource ranking of all spacecraft in the cluster;

[0048] d3) Combining the evaluation results of steps d1) and d2), a cluster head spacecraft is obtained through comprehensive evaluation, which is required to meet both energy optimization and channel optimization.

[0049] Preferably, the relative positioning device configured by S1, S2, ..., Sq includes a differential GNSS compatible machine, a laser radar, and a microwave radar.

[0050] The beneficial effects of the present invention compared with the prior art are:

[0051] (1) The near-space communication of the present invention adopts a communication system that combines two working modes: one-to-many communication and point-to-point communication. On the one hand, it supports the scenario of simultaneous communication between a single spacecraft and multiple spacecraft, and on the other hand, it supports the scenario of high-bandwidth data transmission between two spacecraft.

[0052] (2) The present invention adopts an automatic power control method to solve the problem of near-far effect on return link communication in the scenario of simultaneous communication between a single spacecraft and multiple spacecraft.

[0053] (3) In the adjacent space communication scenario of the present invention, the large and complex spacecraft used as the base station adopts MIMO design, combined with the design method of maximum ratio combining of multi-antenna received signals, to improve the signal-to-noise ratio of the return link received signal and eliminate and reduce the multipath effect.

[0054] (4) In the adjacent space communication scenario of the present invention, an ordinary spacecraft as a user receives the signal sent by a large and complex spacecraft as a base station through multiple antennas at staggered times, and improves the signal-to-noise ratio of the forward link received signal through Rake reception processing and maximum ratio combining methods, thereby eliminating and reducing the multipath effect.

[0055] (5) In the adjacent space communication scenario of the present invention, two working modes, bandwidth adaptation and power adaptation, are supported, which improve the effective data transmission bandwidth based on the original working frequency band, and ultimately improve the bandwidth utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A flow chart of an automatic power control method for resisting near-far effect;

[0057] Figure 2 A flow chart of a return link communication method for resisting multipath effects;

[0058] Figure 3 A flow chart of a forward link communication method for resisting multipath effects;

[0059] Figure 4 The flowchart of link carrier-to-noise ratio decision threshold calculation is shown below;

[0060] Figure 5 This is the principle block diagram of a receiver based on software radio;

[0061] Figure 6 Flowchart of the method for clustering spacecraft in adjacent space;

[0062] Figure 7 Clustering communication flow chart for neighboring spacecraft;

[0063] Figure 8 Flowchart for cluster head screening of spacecraft in neighboring space. DETAILED DESCRIPTION

[0064] The present invention will be further described below in conjunction with the accompanying drawings.

[0065] The present invention proposes a communication method suitable for complex scenes in adjacent space, which meets the needs of simultaneous communication between a single spacecraft and multiple spacecraft in adjacent space, solves the problem of near-far effect caused by this, and solves the multipath effect problem caused by the complex configuration of large spacecraft. Finally, through the method of software radio, the power and bandwidth utilization of adjacent space communication are improved. The present invention is divided into the following five steps:

[0066] In the first step, the adjacent space communication adopts a communication system that combines the two working modes of one-to-many communication and point-to-point communication. The one-to-many communication working mode is suitable for the scenario of simultaneous communication between a single spacecraft and multiple spacecraft, and the transmission bandwidth requirement is low. The point-to-point communication working mode is suitable for the communication scenario of one spacecraft to another spacecraft, and the transmission bandwidth requirement is high. The spacecraft supports both working modes at the same time, and switches the working mode according to the mission requirements to adapt to different working scenarios.

[0067] a) One-to-many communication working mode, using code division multiple access communication system, assigning different GOLD codes to different spacecraft for code division, PN sequence generation polynomial requires different pseudo codes to be assigned to different spacecraft, and maintaining appropriate code intervals. PN sequence code rate is determined according to the effective data bandwidth, transmission bandwidth and spread spectrum ratio requirements.

[0068] b) Point-to-point communication working mode, using time division multiplexing communication system, divides working time slices for different spacecraft, and only two spacecraft communicate with each other in the same time slice. It adopts non-spread spectrum system, and the transmission bandwidth is all used to transmit valid data, which is suitable for high-bandwidth data transmission occasions.

[0069] The second step is to define the transmission direction from a single spacecraft to multiple spacecraft in the one-to-many communication scenario in the adjacent space as forward, and the transmission direction from multiple spacecraft to a single spacecraft as return. Define the single spacecraft as A, and the multiple spacecraft as B1, B2, ..., B n The forward and return links adopt the one-to-many working mode proposed in the first step by default. If there is a temporary large-bandwidth transmission demand, the working mode is switched to the point-to-point communication mode. After completing the large-bandwidth data transmission task, the one-to-many working mode is restored. In the adjacent space scenario, A transmits at a constant power to ensure that B1, B2, ..., B nWithin the range of activity, normal reception can be achieved. B1, B2, …, B n The distances from A are different. If B1, B2, ..., B n Using a constant transmission power will result in different strengths of the return signals received by A, mutual interference between the signals, and a near-far effect, which will eventually cause abnormal return data reception.

[0070] a) A adopts a constant power design, and the transmission power is P At B1, B2, …, B n The design method adopts adjustable transmission power, the transmission power is P Bt1 , P Bt2 ,…,P Btn B1, B2, …, B n According to the received power signal P of A Br1 , P Br2 ,…,P Brn Complete channel estimation and calculate A to B1, B2, ..., B n The channel transmission loss L1, L2, ..., L n , where L i =P At -P Bri ,i=1,…,n,n≥1.

[0071] b) According to the requirements of the adjacent space communication scenario, the optimal receiving power of A is specified as P Ar , according to the channel evaluation result of step a), set B1, B2, ..., B n The transmission power P Bt1 , P Bt2 ,…,P Btn , where P Bti =P Ar +L i +M, i=1,…,n,n≥1, M is the reserved margin, the initial value is 0, and the design of the variation range is related to the dynamic range of receiver A, which is generally 30dB.

[0072] c) If A successfully receives B i (i=1,…,n,n≥1) transmission signal, then reply B i The access is successful. If it fails, B i Increase P by 3dB. Bti , until A successfully receives B i (i=1,…,n,n≥1) transmission signal and send access success message.

[0073] d) After the return link is established, A and B i(i=1,…,n,n≥1) starts the service data interaction. A periodically counts the bit error rate P of the service data. e , calculate the Eb / N0 required to complete the normal business data transmission T , the statistical period is T.

[0074] e) Within the statistical period T, A actually measures the channel and obtains B i (i=1,…,n,n≥1) Eb / N0 of the return link Ri , and Eb / N0 Ri and Eb / N0 T Compare and feed back the comparison result to B via message i (i=1,…,n,n≥1), B i (i=1,…,n,n≥1) according to the message pair P Bti Dynamically adjust in a step-by-step manner with a step length of 1dB to make Eb / N0 Ri Track and get close to Eb / N0 T , and finally the power of each signal received by A is equal, eliminating the near-far effect. For the specific process, see Figure 1 .

[0075] The third step is to use a one-to-many communication scenario in adjacent space. A is usually a complex spacecraft, similar to a base station, and B i (i=1,…,n,n≥1) is an ordinary spacecraft, similar to a user. In order to reduce and eliminate the multipath effect caused by complex configuration and large size on adjacent space communications, a sliding window correlation joint maximum ratio combining method is used at the A end to improve the signal-to-noise ratio of the received signal. i The (i=1,…,n,n≥1) end adopts the RAKE receiving joint maximum ratio combining method to improve the signal-to-noise ratio of the received signal. The specific steps are as follows:

[0076] a) Using MIMO, m (m ≥ 3) pairs of transceiver antennas are installed at equal intervals around the wall of A, B i Only one transmitting and receiving integrated antenna is installed on the bulkhead of (i=1,…,n,n≥1).

[0077] b) A stores all users' return synchronization PN codes internally, B i The PN code (i=1,…,n,n≥1) is denoted as PN i (i=1,…,n,n≥1), receive B through m pairs of antennas respectively i (i=1,…,n,n≥1) return signal.

[0078] c) For each antenna receiving B i The return signal of A uses the internally stored PNi The code is subjected to sliding window correlation to obtain the peak value.

[0079] d) A receives B from all antennas i The return data is combined according to the maximum ratio of the synchronization sequence peak to obtain the highest signal-to-noise ratio and improve the data reception success rate. The return link data reception is now completed. For the specific process, see Figure 2 .

[0080] e) A sends forward signals through m antennas in time-sharing mode, with a sending time interval of t.

[0081] f)B i (i=1,…,n,n≥1) Rake receiver design is adopted, and the internally stored PN code is used for sliding window correlation to obtain the peak value. Taking advantage of the staggered transmission of multiple antennas of A, two more peaks are found in the time slots t before and after the first peak is obtained, and finally the multipath signals are separated for despreading and merging, which effectively improves the signal-to-noise ratio of the received signal and improves the demodulation performance. The specific process is shown in Figure 3 .

[0082] Step 4: To improve the bandwidth and power utilization in adjacent space communication scenarios, A and B i (i=1,…,n,n≥1) Two working modes, bandwidth adaptation and power adaptation, are designed respectively, and the corresponding working mode is selected according to the scene requirements. The specific steps are as follows:

[0083] a) For scenarios that prioritize the energy constraints of the spacecraft, select the power adaptive working mode. A and B i (i=1,…,n,n≥1) respectively evaluate the signal-to-noise ratio of the received signal and compare it with the threshold signal-to-noise ratio of the receiving demodulation to calculate the link margin. Under the premise of ensuring the minimum link margin of 3dB, A and B i (i=1,…,n,n≥1) According to the link margin, the transmission power is appropriately reduced to improve the energy efficiency of the spacecraft.

[0084] b) For scenarios that prioritize transmission bandwidth utilization, select the bandwidth adaptive working mode. A and Bi (i=1,…,n,n≥1) respectively evaluate the signal-to-noise ratio of the received signal, and compare it with the threshold signal-to-noise ratio of the receiving demodulation to calculate the link margin. In order to maximize the use of channel capacity, the decision threshold of the receiver C / N0 is set to J1, J2…Ju. If Jw≤C / N0≤Jw+1(w=1,2…u-1), the transmission bandwidth B and modulation mode are updated accordingly to keep the link margin M basically at around 3dB. See the specific process. Figure 4 Through software radio, the modulation and demodulation working mode is switched according to the current link margin and the threshold signal-to-noise ratio of different demodulation modes. The working principle is shown in Figure 5, based on the original working frequency band, the effective data transmission bandwidth is increased, and the bandwidth utilization rate is ultimately improved.

[0085] The fifth step is to propose a self-organizing network neighboring space communication method based on resource balancing for large-scale spacecraft neighboring space communication scenarios, improve the system flexibility and system robustness of neighboring space communication, and solve the shortcomings of poor system robustness of the neighboring space communication method with traditional fixed network topology. The specific steps are as follows:

[0086] a) First, all spacecraft in the adjacent space communication scenario are numbered as: S1, S2, ..., Sq, q ≥ 3; S1, S2, ..., Sq are respectively equipped with differential GNSS compatible machines, laser radars, microwave radars and other relative positioning devices, and the relative distances between them are measured through the relative positioning devices.

[0087] b) S1, S2, ..., Sq calculate the relative distance measurement results respectively. For example, the relative distances of S1 from S2, ..., Sq are D12, ..., D1q respectively. S1, S2, ..., Sq perform spacecraft clustering design based on their respective measured relative distances. Set the distance threshold to Ds, and several spacecraft with relative distances less than or equal to Ds are divided into the same cluster. All spacecraft in the adjacent space are divided into p clusters: C1, C2, ..., Cp, p≤q. The workflow is shown in Figure 6 shown.

[0088] c) The spacecraft in each cluster are divided into two categories according to their different working roles, namely cluster head spacecraft and ordinary spacecraft. The ordinary spacecraft stores the number information and location information of the cluster head spacecraft. When there is a need for data transmission, the data is directly transmitted to the cluster head spacecraft, or forwarded to the cluster head spacecraft through an intermediate spacecraft, that is, other ordinary spacecraft. The cluster head spacecraft collects the data information of all spacecraft in the cluster, and transmits it to the cluster head spacecraft of the cluster where the target spacecraft is located according to the number information of the target spacecraft contained in the data information, and finally forwards it to the target spacecraft. The workflow is shown in Figure 7 shown.

[0089] Specifically, the spacecraft in each cluster is divided into two categories according to different working roles, namely cluster head spacecraft and ordinary spacecraft, wherein the ordinary spacecraft stores the number information and location information of the cluster head spacecraft, and when there is a need for data transmission, the measured value dm of the relative distance to the cluster head spacecraft is calculated, and according to the comparison result of dm and the forwarding distance threshold dt, if dm≤dt, the data is directly transmitted to the cluster head spacecraft, otherwise, it is forwarded to the cluster head spacecraft through the intermediate spacecraft, that is, other ordinary spacecraft; the cluster head spacecraft summarizes the data information of all spacecraft in the cluster, and determines whether the target spacecraft is in the cluster according to the number information of the target spacecraft contained in the data information, and if it is in the cluster, calculates the measured value dn of the relative distance between the target spacecraft and the cluster head spacecraft, and compares it with the forwarding distance threshold dt, and if dn≤dt, directly forwards the data to the target spacecraft, otherwise, forwards it to the target spacecraft through the intermediate spacecraft;

[0090] If it is not in the cluster, it is transmitted to the cluster head spacecraft of the cluster where the target spacecraft is located. Finally, based on the measured value dn' of the relative distance between the target spacecraft and the cluster head spacecraft of its cluster, if dn'≤dt, the data is directly forwarded to the target spacecraft, otherwise, it is forwarded to the target spacecraft through the intermediate spacecraft.

[0091] d) Regularly evaluate the resources of each spacecraft in the cluster so that the spacecraft with the most resources can serve as the cluster head spacecraft, that is, regularly generate new cluster head spacecraft dynamically so that each spacecraft in the cluster can take turns to serve as the cluster head spacecraft, thereby avoiding the phenomenon that a certain spacecraft serves as the cluster head for a long time, which causes the spacecraft to be unable to work or even malfunction after the resources are exhausted. The evaluation object is the resources of the spacecraft. For the adjacent space communication scenario, the resources are concretized as the energy balance and bandwidth resources of the spacecraft. Due to the differences in the current orbit and operating attitude of each spacecraft, the illumination degree and power generation capacity of the solar wing sails are different. At the same time, each spacecraft is equipped with battery packs of different capacities, and the current discharge depth and remaining energy of the battery are also different. In addition, the workload of each spacecraft at the same time is also different. Based on this, a cluster head screening method based on energy balance optimization of neighboring spacecraft network is proposed. The current battery remaining energy of each spacecraft in the cluster, the power generation capacity of the solar wing sailboard and the current workload of the spacecraft are calculated in real time to obtain the comprehensive energy Ej of the spacecraft Sj, Ej = Xj + Fj - Pj * T', where Xj is the remaining energy of the battery, Fj is the power generation of the solar wing sailboard, Pj is the current load power of the spacecraft, T' is the working cycle, j = 1, 2, ..., p, j ≤ p; the comprehensive energy of each spacecraft is compared to obtain the spacecraft with the most abundant comprehensive energy in the current evaluation period, and the comprehensive energy resource ranking of all spacecraft in the cluster is given.

[0092] e) Regularly evaluate the bandwidth resources of each spacecraft in the cluster. The resource configurations of the RF transmitter, RF receiver, and RF antenna of each spacecraft are different. At the same time, the occupancy of the RF transmission channel resources of each spacecraft at the current moment is different. Based on this, an optimized cluster head screening method based on the RF channel resources of the adjacent spacecraft network is proposed. The RF channel resources and occupancy of each spacecraft in the cluster are calculated in real time, and the spacecraft with the best channel resources in the current evaluation period is obtained, and the bandwidth resource ranking of all spacecraft in the cluster is given.

[0093] f) Combine the evaluation results of steps d) and e) to obtain the cluster head spacecraft through comprehensive evaluation. The cluster head spacecraft is required to meet both energy optimization and bandwidth optimization. This method can effectively save the energy of a single spacecraft, balance the energy consumption of the spacecraft network, and extend the life cycle of the spacecraft network. The workflow is shown in Figure 8 shown.

[0094] The present invention meets the needs of simultaneous communication between a single spacecraft and multiple spacecraft in adjacent space, and solves the problem of near-far effect caused by this, while also solving the problem of multipath effect caused by the complex configuration of large spacecraft. Finally, through the method of software radio, the power and bandwidth utilization of adjacent space communications are improved.

[0095] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A communication method suitable for complex scenes in adjacent spaces, characterized in that: include: The adjacent space communication adopts a communication system that combines two working modes: one-to-many communication and point-to-point communication. It is stipulated that in the one-to-many communication scenario in adjacent space, the transmission direction from a single spacecraft to multiple spacecraft is the forward direction, and the transmission direction from multiple spacecraft to a single spacecraft is the return direction. The forward and return links adopt the one-to-many communication working mode by default. If there is a temporary high-bandwidth transmission demand, the working mode will be switched to the point-to-point communication mode. After completing the high-bandwidth data transmission task, the one-to-many communication working mode will be restored. In the one-to-many communication scenario in adjacent space, let the single spacecraft be A and the multiple spacecraft be B1, B2, …, B n At the A end, a sliding window-based joint maximum ratio combining method is used to improve the signal-to-noise ratio of the received signal. i The end uses the RAKE receiving joint maximum ratio combining method to improve the signal-to-noise ratio of the received signal, i = 1, ..., n, n ≥ 1; A and B i Design two working modes: bandwidth adaptation and power adaptation, and select the corresponding working mode according to the scenario requirements; According to the above design, large-scale spacecraft adjacent space communication is realized by the self-organizing network adjacent space communication method based on resource balancing.

2. A communication method applicable to complex scenes in adjacent spaces according to claim 1, characterized in that: The one-to-many communication working mode adopts the code division multiple access communication system, assigns different spread spectrum codes to different spacecraft, and maintains an appropriate distance between codes. The spread spectrum code rate is determined according to the effective data bandwidth, transmission bandwidth and spread spectrum ratio requirements.

3. A communication method applicable to complex scenes in adjacent spaces according to claim 1, characterized in that: The point-to-point communication working mode adopts a time-division multiplexing communication system to divide the working time slices for different spacecraft. Only two spacecraft communicate with each other in the same time slice. A non-spread spectrum system is adopted, and all the transmission bandwidth is used to transmit valid data.

4. A communication method applicable to complex scenes in adjacent spaces according to claim 1, characterized in that: The forward return link adopts an automatic power control method that resists the near-far effect. The specific implementation method is as follows: a) A adopts a constant power design, and the transmission power is P At ; B1, B2, …, B n The transmission power is P Bt1 , P Bt2 ,…,P Btn , and B1, B2, …, B n Transmit power adjustable, B1, B2, ..., B n According to the received power signal P of A Br1 , P Br2 ,…,P Brn Complete channel evaluation and calculate A to B1, B2, ..., B respectively. n The channel transmission loss L1, L2, ..., L n ; b) According to the requirements of the adjacent space communication scenario, the optimal receiving power of A is specified as P Ar , according to the channel evaluation result of step a), set B1, B2, ..., B n The transmission power P Bt1 , P Bt2 ,…,P Btn , where P Bti =P Ar +L i +M, i=1,…,n, n≥1, M is the reserved margin, and the initial value is 0; c) If A successfully receives B i The transmission signal is then replied to B i The access is successful. If it fails, B i Increase P by 3dB. Bti , until A successfully receives B i The transmitting signal and the access success message are sent; d) After the return link is established, A and B i Business data interaction begins. A periodically collects statistics on the bit error rate P of business data. e , calculate the theoretical value of the signal-to-noise ratio Eb / N0 required to complete the normal business data transmission T , the statistical period is T; e) Within the statistical period T, A actually measures the channel and obtains B i The actual measured value of the signal-to-noise ratio of the return link is Eb / N0 Ri , and Eb / N0 Ri and Eb / N0 T Compare and feed back the comparison result to B via message i , B i According to the news, P Bti Dynamically adjust in a step-by-step manner with a step length of 1dB to make Eb / N0 Ri Track and get close to Eb / N0 T , ultimately achieving the goal of equal power of each signal received by A and eliminating the near-far effect.

5. A communication method applicable to complex scenes in adjacent spaces according to claim 4, characterized in that: L i =P At -P Bri ,i=1,…,n,n≥1。 6. A communication method applicable to complex scenes in adjacent spaces according to claim 1, characterized in that: At the A end, a sliding window correlation-based joint maximum ratio combining method is used to improve the signal-to-noise ratio of the received signal. i The end uses the RAKE receiving joint maximum ratio combining method to improve the signal-to-noise ratio of the received signal and realize anti-multipath communication. The specific implementation method is as follows: a) Using MIMO, m pairs of transceiver antennas are installed at equal intervals around the wall of A, B i Only one transceiver antenna is installed on the bulkhead, m≥3; b) User B of A's internal storage i The return synchronization PN code, that is, PN i , receiving B through m antennas respectively i Return signal; i=1,…,n,n≥1; c) For each antenna receiving user B i The return signal, A uses the internally stored PN code PN i Perform sliding window correlation to obtain the peak value; d) A receives user B from all antennas i The data is combined with the maximum ratio according to the peak value obtained by sliding window correlation to obtain the highest signal-to-noise ratio, thus completing the return link data reception; e) A sends forward signals through m antennas in time division, with a sending time interval of t; f)B i The Rake receiver design is adopted, and the PN code of A stored internally is used to perform sliding window correlation on the received forward signal to obtain the peak value. By utilizing the property of A's multi-antenna staggered transmission, another two peak values ​​are found in the time slots t before and after the first peak value is obtained, and finally the multipath signals are separated for despreading and merging.

7. The communication method applicable to complex scenes in adjacent spaces according to claim 1, characterized in that: A and B i , i=1,…,n,n≥1, respectively design bandwidth adaptive and power adaptive working modes, and select the corresponding working mode according to the scene requirements. The specific steps are as follows: a) For scenarios that prioritize the energy constraints of spacecraft, select the power adaptive working mode: A and B i The signal-to-noise ratio of the received signal is evaluated respectively, and compared with the threshold signal-to-noise ratio of the receiving demodulation, and the link margin is calculated. Under the premise of ensuring the minimum link margin of 3dB, A and B i According to the link margin, the transmission power can be appropriately reduced to improve the energy efficiency of the spacecraft; b) For scenarios where transmission bandwidth utilization is a priority, select the bandwidth adaptive working mode: A and Bi evaluate the signal-to-noise ratio of the received signal respectively, and compare it with the threshold signal-to-noise ratio of the receiving demodulation to calculate the link margin; set the decision threshold of the receiver C / N0 to J1, J2…Ju; Let the initial value of w be 1 and perform the following steps: b1) If Jw≤C / N0≤Jw+1, then the decision threshold of C / N0 = Jw, otherwise go to b2); b2) Determine whether w is u-1. If not, add 1 to the value of w and repeat b1); if w = u-1, the decision threshold of C / N0 = Jw, and the process ends; Update the transmission bandwidth B and modulation mode according to the decision threshold of C / N0 to maintain the link margin M at 3dB; c) By means of software radio, the modulation and demodulation working modes are switched according to the current link margin and the threshold signal-to-noise ratio of different demodulation modes.

8. The communication method applicable to complex scenes in adjacent spaces according to claim 1, characterized in that: The specific steps of the self-organizing network adjacent space communication method based on resource balancing are as follows: a) First, all spacecraft in the adjacent space communication scenario are numbered as: S1, S2, ..., Sq, q ≥ 3; S1, S2, ..., Sq are respectively equipped with relative positioning devices, and the relative distances between them are measured by the relative positioning devices; b) S1, S2, ..., Sq calculate the relative distance measurement results respectively, and cluster the spacecraft according to the relative distance measurement results. The clustering method is as follows: Set the distance threshold to Ds, and divide the spacecraft whose relative distance measurement results are less than or equal to Ds into the same cluster. Divide all spacecraft in the adjacent space into p clusters: C1, C2, ..., Cp, p≤q; c) The spacecraft in each cluster are divided into two categories according to their different working roles, namely cluster head spacecraft and ordinary spacecraft. The ordinary spacecraft stores the number information and location information of the cluster head spacecraft. When there is a need for data transmission, the measured value dm of the relative distance to the cluster head spacecraft is calculated. According to the comparison result of dm and the forwarding distance threshold dt, if dm≤dt, the data is directly transmitted to the cluster head spacecraft, otherwise, it is forwarded to the cluster head spacecraft through the intermediate spacecraft, that is, other ordinary spacecraft; the cluster head spacecraft summarizes the data information of all spacecraft in the cluster, and determines whether the target spacecraft is in the cluster according to the number information of the target spacecraft contained in the data information. If it is in the cluster, the measured value dn of the relative distance between the target spacecraft and the cluster head spacecraft is calculated and compared with the forwarding distance threshold dt. If dn≤dt, the data is directly forwarded to the target spacecraft, otherwise, it is forwarded to the target spacecraft through the intermediate spacecraft; If it is not in the cluster, it is transmitted to the cluster head spacecraft of the cluster where the target spacecraft is located. Finally, according to the measured value dn' of the relative distance between the target spacecraft and the cluster head spacecraft of its cluster, if dn'≤dt, the data is directly forwarded to the target spacecraft, otherwise, it is forwarded to the target spacecraft through the intermediate spacecraft; d) Regularly evaluate the resources of each spacecraft in the cluster so that the spacecraft with the most resources can serve as the cluster head spacecraft, that is, dynamically generate a new cluster head spacecraft regularly; The method for generating cluster head spacecraft is as follows: d1) Calculate the current remaining battery energy, the power generation capacity of the solar panels and the current workload of each spacecraft in the cluster in real time, and obtain the comprehensive energy Ej of the spacecraft Sj, Ej = Xj + Fj - Pj * T', where Xj is the remaining battery energy, Fj is the power generation of the solar panels, Pj is the current load power of the spacecraft, T' is the working cycle, j = 1, 2, ..., p, j ≤ p; compare the comprehensive energy of each spacecraft, obtain the spacecraft with the most abundant comprehensive energy in the current evaluation cycle, and give the comprehensive energy resource ranking of all spacecraft in the cluster; d2) Calculate the RF channel resources and occupancy of each spacecraft in the cluster in real time, find the spacecraft with the best channel resources in the current evaluation period, and give the channel resource ranking of all spacecraft in the cluster; d3) Combining the evaluation results of steps d1) and d2), a cluster head spacecraft is obtained through comprehensive evaluation, which is required to meet both energy optimization and channel optimization.

9. A communication method applicable to complex scenes in adjacent spaces according to claim 8, characterized in that: The relative positioning device configured by S1, S2, ..., Sq includes a differential GNSS compatible machine, a laser radar, and a microwave radar.

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