CN-122026988-A - Contact plan construction and multi-hop relay path selection method for earth-Mars communication

CN122026988ACN 122026988 ACN122026988 ACN 122026988ACN-122026988-A

Abstract

The invention relates to a contact plan construction and multi-hop relay path selection method for earth-Mars communication, and belongs to the technical field of deep space communication. According to the method, a contact plan is generated based on orbit dynamics and geometric visibility, the availability of a link is judged by integrating planetary shielding and solar synthetic day constraint, the achievable bit rate of the link is estimated, a time-varying weighted communication network is constructed, and a simultaneous or continuous communication strategy is selected to perform optimal path searching according to the parallel transceiving capacity of a relay node. The method solves the problem of communication interruption caused by link time variability, shielding and solar interference in the ground fire communication, and remarkably improves the usability, continuity and end-to-end transmission efficiency of the communication.

Inventors

XU GUANJUN
LI CHUQING
GAO MIN
ZHU LINA

Assignees

杭州电子科技大学

Dates

Publication Date: 20260512
Application Date: 20260127

Claims (10)

1. The contact plan construction and multi-hop relay path selection method for the earth-Mars communication is characterized by comprising the following steps of: S1, generating a contact plan between any communication nodes on a discrete time sequence based on orbit dynamics and geometric visibility; s2, in each time step, comprehensively judging the availability of the link by the satellite shielding and sun-closing constraint, and quantitatively evaluating the achievable bit rate of the available link; s3, constructing a time-varying communication network with weight according to the link performance evaluation result; and S4, executing optimal path search by adopting a simultaneous communication strategy or a continuous communication strategy according to whether the relay node has parallel transceiving capability, and outputting an optimal multi-hop forwarding path from the source node to the destination node, and corresponding communication availability and end-to-end equivalent bit rate.
2. The contact plan construction and multi-hop relay path selection method for earth-spark communications of claim 1, wherein in S2, said determining link availability comprises: For the situation that the communication node is not positioned on the surface of the shielding celestial body, calculating a shielding time window of a third celestial body to sight links of the two communication nodes based on STK software, and determining that the link in the time window is unavailable; For links between a ground station or lander and other nodes, adopting a determination mode based on elevation constraint, taking a minimum elevation threshold value as a system parameter, obtaining an elevation communicable time window when the elevation angle meets a threshold value condition, and defining a final utilizable communication window as an intersection of the elevation communicable time window and a celestial body shielding time window; The sun's effect is included in the contact plan's unavailable decision, specifically comprises calculating the included angle SEP of sun-earth-detector, and setting the sun total-day judgment threshold As a system parameter, when When the link is determined to be in the sun-resultant interference area, the link visibility is set to 0.
3. The method for contact planning construction and multi-hop relay path selection for earth-spark communications of claim 1, wherein in S2 said quantitatively evaluating achievable bit rates for available links is based on a signal-to-noise ratio SNR calculation expressed as: Where P t is the transmit power, G t is the transmit antenna gain, G r is the receive antenna gain, L is the product of free space path loss, antenna hardware loss, polarization loss, and pointing loss, B is the channel bandwidth, k B is the Boltzmann constant, and T sys is the system equivalent noise temperature; determining a maximum bandwidth B max given a minimum acceptable signal-to-noise ratio SNR min , and deriving a maximum allowed symbol rate S and a maximum bit rate R max based on the modulation scheme; For quadrature phase shift keying, QPSK, modulation, the relationship of bit rate R to symbol rate S is r=2s; When the local fire communication channel sets the maximum bandwidth Bchannel, the maximum bit rate R max is limited to B channel , i.e. if B max ＞B channel , R max =2B channel .
4. The method for constructing a contact plan and selecting a multi-hop relay path for earth-spark communications according to claim 1, wherein in S4, the simultaneous communication strategy is applied to a case where the relay node has parallel transceiving capability, and the equivalent bit rate RT of the path is defined as a minimum value of achievable bit rates of each hop of the path: where M is the number of hops in the path; The continuous communication strategy is suitable for the situation that the relay node does not have parallel receiving and transmitting capability, and the equivalent bit rate R T of the path is defined as the transmission data quantity D and the total time of end-to-end transmission Wherein the total time of end-to-end transmission The sum of the transmission time of each hop is: the equivalent bit rate R T satisfies: Where R i is the achievable bit rate of the ith hop.
5. The contact planning construction and multi-hop relay path selection method for earth-spark communications of claim 1, wherein in S4, said performing an optimal path search comprises: Modeling path search as a maximum bottleneck problem for a simultaneous communication strategy, and solving an optimal path by adopting a widest path algorithm; for a continuous communication strategy, the cost of a single-hop link is defined as time consumption for transmission, and a Di Jie Tesla algorithm is adopted to solve the minimum total cost path.
6. The method for contact planning construction and multi-hop relay path selection for earth-spark communications of claim 1 further comprising introducing virtual nodes to support a scenario of multiple source nodes and/or multiple destination nodes, wherein the virtual nodes are connected only to the set of candidate nodes they represent and set an equivalent bit rate or zero cost that is large enough to ensure that no additional bottlenecks are introduced.
7. An earth-spark communication oriented contact plan construction and multi-hop relay path selection system, characterized in that the system comprises: The contact plan construction module is used for generating a contact plan between any communication nodes on a discrete time sequence based on orbit dynamics and geometric visibility information; The link performance evaluation module is used for comprehensively judging the availability of the link by the planetary shielding and solar total-day constraint in each time step and quantitatively evaluating the transmission performance of the available link; the forwarding strategy selection module is used for selecting a simultaneous communication strategy or a continuous communication strategy according to whether the relay node communication load has parallel receiving and transmitting capability or not; the time-varying network construction module is used for constructing a corresponding time-varying weighted communication network according to the selected communication strategy; And the path searching module is used for searching the optimal multi-hop forwarding path from the source node to the destination node on the time-varying weighted communication network and outputting corresponding end-to-end communication performance indexes.
8. The earth-spark communication-oriented contact plan construction and multi-hop relay path selection of claim 7, wherein the system comprises a ground segment and a space segment, wherein the ground segment comprises a set of ground station nodes, and the space segment comprises a set of spark detectors and relay nodes for constructing an earth-fire relay network; The relay node set is arranged near the Lagrange point of the sun-earth system L3, L4 or L5, or on a circular or round-the-sun orbit between the earth and the Mars.
9. The earth-spark communication oriented contact plan construction and multi-hop relay path selection of claim 8, wherein the set of ground station nodes comprises deep space measurement and control stations of a China deep space measurement and control network CDSN, the deep space measurement and control stations comprising a Canon deep space measurement and control station, a Keshen deep space measurement and control station and an Argentina overseas deep space measurement and control station.
10. The earth-spark communication-oriented contact plan construction and multi-hop relay path selection of claim 7 wherein said relay node employs regenerative relaying to demodulate, decode and perform error detection and correction EDAC of the received signal prior to forwarding, and then re-encode, modulate and send to the next communication node.

Description

Contact plan construction and multi-hop relay path selection method for earth-Mars communication Technical Field The invention belongs to the technical field of deep space communication, and relates to a contact plan construction and multi-hop relay path selection method for earth-spark communication. Background The Mars detection task is an important component in the field of deep space detection, and is also a key link of future interplanetary detection and manned deep space tasks. In the earth and spark communications scenario, the communications link spans very long distances and the relative positions of the earth and spark change over time, resulting in significant dynamics in latency, path loss, and availability of the communications link. The distance between the earth and the mars varies widely during the mars convergence period with a maximum distance to minimum distance ratio of about seven to three, which causes the data transmission rate and available time window of the communication link to fluctuate dramatically with track position. Meanwhile, the Mars detection task, especially the future manned Mars task, has higher requirements on the communication system, and needs to support large-capacity data transmission and stable services such as voice, video and the like. The direct communication link between earth and spark may be interrupted or severely degraded over a significant period of time due to sun-and-planet shielding and ground station back-facing factors. Thus, a single direct link is difficult to meet the reliability and continuity requirements of a ground fire communication task. A multi-hop relay mechanism is introduced, and a communication network between the earth and the Mars is constructed by utilizing a plurality of relay satellites or planetary orbiters, so that the communication network becomes an effective means for improving the usability of communication and the robustness of the system. However, in an inter-planetary communication network in which multiple relay nodes participate, the availability of links has obvious time variability, the communicable time between different nodes presents discrete contact characteristics, and the communication system needs to plan a contact plan in advance and perform multi-hop path selection. Meanwhile, different links have significant differences in propagation distance, channel condition, system load and the like, so that how to perform efficient multi-hop relay path selection on the premise of meeting communication constraint becomes a key technical problem in the design of a ground fire communication system. The prior art lacks a systematic method, can accurately evaluate the link performance under the time-varying topology condition, and realizes the dynamic selection of the optimal path, thereby limiting the overall performance of the communication network. Therefore, it is necessary to propose a contact plan construction and multi-hop relay path selection method for earth and spark communication, so as to solve the above problems and improve the communication availability and the end-to-end transmission performance of the deep space communication network. Disclosure of Invention In view of the above, the present invention aims to provide a contact plan construction and multi-hop relay path selection method for earth-spark communication. In order to achieve the above purpose, the present invention provides the following technical solutions: A contact plan construction and multi-hop relay path selection method for earth-spark communication, the method comprising the steps of: S1, generating a contact plan between any communication nodes on a discrete time sequence based on orbit dynamics and geometric visibility; S2, in each time step, comprehensively judging the availability of the link by the satellite shielding and sun-closing constraint, and quantitatively evaluating the achievable bit rate of the available link; S3, constructing a time-varying communication network with weight according to the link performance evaluation result; And S4, executing optimal path search by adopting a simultaneous communication strategy or a continuous communication strategy according to whether the relay node has parallel transceiving capability, and outputting an optimal multi-hop forwarding path from the source node to the destination node, and corresponding communication availability and end-to-end equivalent bit rate. Further, in S2, the determining the link availability includes: For the situation that the communication node is not positioned on the surface of the shielding celestial body, calculating a shielding time window of a third celestial body to sight links of the two communication nodes based on STK software, and determining that the link in the time window is unavailable; For links between a ground station or lander and other nodes, adopting a determination mode based on elevation constraint, taking a minimum elevation threshold val