CN113573177A - Deep space optical communication network channel directional access method - Google Patents
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Abstract
The invention provides a deep space optical communication network channel directional access method, and relates to the field of communication methods. A deep space optical communication network channel directional access method comprises the following steps that a multi-interface model of deep space optical communication is configured in an NS2 simulation environment; establishing a deep-space optical communication channel transmission model according to a mathematical transmission model of a deep-space optical communication link, and adding the deep-space optical communication link transmission model in a Two-Rayground model in NS2 simulation software; the method comprises the steps that a plurality of nodes are configured through NS2 simulation software, each node is initialized, each node is configured with 1 detector and a plurality of laser transmitters, the detectors are used for detecting and receiving signals sent by the laser transmitters, the laser transmitters are uniformly distributed around the circumference of the node, and when the nodes communicate, the closer laser transmitters are selected to send the signals.
Description
Technical Field
The invention relates to the field of communication methods, in particular to a deep space optical communication network channel directional access method.
Background
Deep space Communication (Deep-space Communication) is a foundation and a support for Deep space exploration, and plays a key role in Deep space exploration engineering. Compared with the traditional microwave communication, the laser communication has the advantages of large capacity, strong confidentiality, portability, miniaturization and the like, and is known as one of the transmission technologies with great prospects in a deep space communication system. With the continuous maturation of the space laser communication technology and the development of the deep space detector technology, the deep space optical communication network is expected to become an important infrastructure of the future deep space communication, and the trend of inevitable development is achieved. In addition, the deep space optical communication network is a strategic infrastructure for realizing a deep space high-speed information channel, and a strategic system for realizing seamless coverage in the global or even space range based on the deep space optical communication network provides powerful technical support for navigation positioning, deep space exploration, remote sensing and telemetering and the like. However, the characteristics of angle sensitivity, line-of-sight transmission, long transmission distance of deep space communication and the like of laser communication provide higher challenges for the access method of the deep space optical communication backbone network.
Although deep space optical communication has the characteristics of high capacity, strong confidentiality, portability, miniaturization and the like which are superior to deep space radio communication, the transmission distance is far, the receiving signal-to-noise ratio is low due to serious path attenuation, and errors are easy to occur in the transmission process. The deep space optical communication is different from the wireless radio frequency communication, and has the characteristics of narrow transmission beam and line-of-sight communication, and the coverage range has certain directivity. Therefore, the directional access method for deep space optical communication has practical application value, and reasonable distribution and management of channel resources are one of the key problems of the deep space optical communication network.
Disclosure of Invention
The invention aims to provide a deep space optical communication network channel directional access method which can realize reasonable distribution and management of channel resources.
The embodiment of the invention is realized by the following steps:
the embodiment of the application provides a deep space optical communication network channel directional access method, which comprises the following steps,
step 1-1: configuring a multi-interface model of deep space optical communication in an NS2 simulation environment;
step 1-2: establishing a deep-space optical communication channel transmission model according to a mathematical transmission model of a deep-space optical communication link, and adding the deep-space optical communication link transmission model in a Two-Rayground model in NS2 simulation software;
step 1-3: the method comprises the steps that a plurality of nodes are configured through NS2 simulation software, each node is initialized, each node is configured with 1 detector and a plurality of laser transmitters, the detectors are used for detecting and receiving signals sent by the laser transmitters, the laser transmitters are uniformly distributed around the circumference of the node, and when the nodes communicate, the closer laser transmitters are selected to send the signals.
In some embodiments of the present invention, the above method for directionally accessing a deep space optical communication network channel further includes the following steps, step 2, the node performs communication: all nodes are in a scanning mode, a source node A and a destination node B are set, whether a channel is in an idle state or not is judged, if not, the node A sends data to the node B, and if not, the scanning mode is returned.
In some embodiments of the present invention, the determining whether the channel is idle includes the following steps: and configuring a directional network allocation vector value for each interface of the laser transmitter and the detector, wherein the directional network allocation vector value is used for setting the predicted occupation time of node transmission, and judging whether the channel is in an idle state or not according to the directional network allocation vector value.
In some embodiments of the present invention, when the directional network allocation vector value of the interface is zero, it is determined that the channel is in an idle state, otherwise, the opposite is true.
In some embodiments of the present invention, the above method for directionally accessing a channel of a deep space optical communication network further includes the following steps, step 3 exchanges RTS/CTS: if the channel is in idle state, judging whether the node A belongs to the vicinity of the node B, if so, selecting an interface with a zero network allocation vector value to send an RTS frame to the node B, otherwise, selecting an interface with a zero network allocation vector value and close to the node B, and sending the RTS frame to the node B through an intermediate node C of the interface.
In some embodiments of the invention, step 3 further comprises the steps of: after node A sends RTS frame to node B, waiting for node B to reply CTS frame in short frame interval, when node A and node B exchange RTS frame and CTS frame successfully, channel reservation succeeds, otherwise, repeating step 2.
In some embodiments of the present invention, the above method for directionally accessing a deep space optical communication network channel further includes the following steps, step 4, data exchange: step 4-1: after the channel reservation is successful, the node a sends data to the node B through an interface close to the node B.
In some embodiments of the invention, step 4 further comprises the steps of: and when the node B receives the data, selecting an interface close to the node A to reply the ACK frame, when the node A receives the ACK frame, successfully transmitting the data, otherwise, repeating the step 3 if the data transmission fails.
In some embodiments of the present invention, each node creates a neighbor table, stores interfaces with close distances to other nodes in the neighbor table, and searches for an interface close to a node according to the neighbor table.
In some embodiments of the present invention, the above method for directionally accessing a deep space optical communication network channel further includes the following steps, step 5: and analyzing the simulation result by using the throughput, the fairness, the time delay and the space division multiplexing rate of the channel.
Compared with the prior art, the embodiment of the invention has at least the following advantages or beneficial effects:
the embodiment of the application provides a deep space optical communication network channel directional access method, which comprises the following steps of 1, network initialization: step 1-1: configuring a multi-interface model of deep space optical communication in an NS2 simulation environment; step 1-2: establishing a deep-space optical communication channel transmission model according to a mathematical transmission model of a deep-space optical communication link, and adding the deep-space optical communication link transmission model in a Two-Rayground model in NS2 simulation software; step 1-3: the method comprises the steps that a plurality of nodes are configured through NS2 simulation software, each node is initialized, each node is configured with 1 detector and a plurality of laser transmitters, the detectors are used for detecting and receiving signals sent by the laser transmitters, the laser transmitters are uniformly distributed around the circumference of the node, and when the nodes communicate, the closer laser transmitters are selected to send the signals.
According to the method, the deep space optical communication network channel directional access method is provided by configuring the multi-interface model of the deep space optical communication in the NS2 simulation environment, aiming at the sensitive characteristics of the deep space optical communication to angles and directions, the plurality of laser transmitters are uniformly distributed around the circumference of each node, so that the laser transmitters closest to the receiving nodes are used for transmitting signals during communication, the detectors of different nodes are used for detecting and receiving the signals, and the space division multiplexing and the frequency division multiplexing are combined. The invention allocates wireless channel resources for different nodes, namely, controls how a medium accesses a channel to transmit data. A plurality of transceivers covering a certain range are configured for different nodes, so that adjacent interfaces are selected for communication, and reasonable distribution and management of channel resources are realized. The directional working antenna is adopted for sending and receiving signals, and compared with the omnidirectional antenna, the MAC protocol supporting the directional antenna can effectively solve the problem of terminal exposure, and meanwhile, the problem of terminal hiding is greatly reduced. The directional antennas actually separate the space, and separate the possible collisions in the omnidirectional mode in the transmission direction, so that not only can the interference area be reduced, thereby improving the space division multiplexing rate of the channel, but also the transmission hop count and the grouping collision of the data packets can be reduced, the network performance is improved, and the node throughput is effectively improved. And part of nodes are supported to utilize multi-hop routing transmission, so that the non-directivity and blindness of an omnidirectional routing method are avoided, and more energy is saved. In addition, the deep space optical communication and the wireless network are combined, so that the advantage of sensitive sensing of the deep space optical communication can be exerted, and the communication distance can be enlarged through multi-hop transmission.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic diagram of a deep space optical communication node multi-interface model according to the present invention;
FIG. 2 is a communication scenario diagram of a directional routing method according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a chain topology of the present invention;
FIG. 4 is a diagram illustrating the throughput comparison of different node numbers of the DMAC method and the NDMAC method according to the present invention;
FIG. 5 is a schematic diagram illustrating a chain topology multi-hop throughput comparison between a DMAC method and an NDMAC method according to the present invention;
FIG. 6 is a schematic diagram illustrating a chain topology multi-hop delay comparison between a DMAC method and an NDMAC method according to the present invention;
FIG. 7 is a mesh topology of the present invention;
FIG. 8 is a graph illustrating the throughput comparison between the DMAC method and the NDMAC method in mesh topology;
fig. 9 is a schematic diagram illustrating mesh topology time delay comparison between the DMAC method and the NDMAC method in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the description of the present application, it is also to be noted that, unless otherwise explicitly specified or limited, the terms "disposed" and "connected" are to be interpreted broadly, e.g., as being either fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.
Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The embodiments described below and the individual features of the embodiments can be combined with one another without conflict.
Examples
Referring to fig. 1 to 9, fig. 1 to 9 are schematic flow charts illustrating a deep space optical communication network channel directional access method according to an embodiment of the present application. The channel directional access method for the deep space optical communication network comprises the following steps,
step 1-1: configuring a multi-interface model of deep space optical communication in an NS2 simulation environment;
step 1-2: establishing a deep-space optical communication channel transmission model according to a mathematical transmission model of a deep-space optical communication link, and adding the deep-space optical communication link transmission model in a Two-Rayground wireless transmission model in NS2 simulation software;
step 1-3: the method comprises the steps that a plurality of nodes are configured through NS2 network simulation software, each node is initialized, each node is configured with 1 detector and a plurality of laser transmitters, the detectors are used for detecting and receiving signals sent by the laser transmitters, the laser transmitters are uniformly distributed around the circumference of the node, and when the nodes communicate, the closer laser transmitters are selected to send the signals.
The network simulation environment is set first and is sent to the positions of nearby neighbor nodes through nodes in the network, and multiple sets of transceivers are configured for each node. Each node can store the positions of the neighbor nodes, and the target node is convenient to select. In detail, the transceiver comprises a plurality of laser transmitters for transmitting information from the node and a detector for receiving and detecting the information. Thus, each node can send multiple messages simultaneously, and different nodes can only receive messages from one node at a time. Each transceiver has a coverage area within a certain range, so that an interface corresponding to a neighbor node can be selected for communication during communication.
In step 1-1, corresponding configuration is mainly performed on an ns-lib.tcl file, an ns-mobilen.tcl file, and an Address Resolution Protocol (ARP).
Step 1-2: the deep space optical communication channel transmission model is established according to the deep space optical communication link mathematical transmission model, and when deep space optical communication is carried out, signals are not influenced by atmospheric turbulence in the transmission process. In a deep space inter-satellite optical communication system, signal light power emitted by a laser is subjected to attenuation of a transmitting optical system, transmitting antenna gain, deep space channel fading, background noise influence such as solar wind corona, tracking error attenuation, receiving optical system attenuation and receiving antenna gain, and finally the communication light power is received by a detector.
The received power of the deep space optical communication link transmission model can be expressed as:
PR＝PTηTηRGTGRLTLR(λ/4πd)2；
the known parameters and variables involved therein are defined as follows: pRRepresents the received power of the system; pTRepresents a transmit power; etaTRepresenting the transmission efficiency of the system; etaRRepresenting the reception efficiency of the system; gRRepresents the receive gain of the system; gTRepresenting the transmit gain of the system; l isRRepresenting a receive aiming error factor; l isTRepresenting a firing sighting error factor; λ represents a communication wavelength; d represents a communication distance.
Optionally, in step 1-3, the NS2 simulation software configures a plurality of nodes in a certain area (e.g., 1200 × 1200), the initial energy for initializing each node is 10J, the transmitting equipment of each node configures 6 laser transmitters, and the areas covered by the 6 laser transmitters are all sectors, the field angle of the sector is 60 °, and a laser transmitter in a closer direction may be selected for transmitting a signal during communication.
In detail, each node is also configured with 1 detector for detecting and receiving signals, and the parameters thereof may be set as: the bit rate is 2Mbps, the wavelength of the laser is 1550nm, the node energy is 10J, the aperture of each transmitting antenna and the aperture of each receiving antenna are both 15cm, and the transmitting efficiency and the receiving efficiency of each antenna are both 0.8.
In summary, the DMAC method proposed by the present invention fully combines space division multiplexing and frequency division multiplexing based on a multi-interface deep space node model design for the sensitive characteristics of deep space optical communication to angles and orientations, and the design supports a directional access method, and simulation results show that, compared with the NDMAC method, the DMAC method proposed in the present invention can greatly improve network throughput, reduce transmission delay, effectively improve network performance, and fully utilize network link resources, thereby saving network resources and improving the lifetime of the entire deep space optical network.
According to the method, the deep space optical communication network channel directional access method is provided by configuring the multi-interface model of the deep space optical communication in the NS2 simulation environment, aiming at the sensitive characteristics of the deep space optical communication to angles and directions, the plurality of laser transmitters are uniformly distributed around the circumference of each node, so that the laser transmitters closest to the receiving nodes are used for transmitting signals during communication, the detectors of different nodes are used for detecting and receiving the signals, and the space division multiplexing and the frequency division multiplexing are combined. The invention allocates wireless channel resources for different nodes, namely, controls how a medium accesses a channel to transmit data. A plurality of transceivers covering a certain range are configured for different nodes, so that adjacent interfaces are selected for communication, and reasonable distribution and management of channel resources are realized. In addition, the deep space optical communication and the wireless network are combined, so that the advantage of sensitive sensing of the deep space optical communication can be exerted, and the communication distance can be enlarged through multi-hop transmission.
Space Division Multiplexing (SDM) is a Multiplexing system in which a plurality of pairs of wires or optical fibers share 1 cable. Frequency Division Multiplexing (FDM) is the Division of the total bandwidth for a transmission channel into several sub-bands (or sub-channels), each of which transmits 1 channel of signals.
As shown in fig. 2, in some embodiments of the present invention, the above-mentioned deep space optical communication network channel directional access method further includes the following steps, step 2, the node performs communication: all nodes are in a scanning mode, a source node A and a destination node B are set, whether a channel is in an idle state or not is judged, if not, the node A sends data to the node B, and if not, the scanning mode is returned.
In detail, whether the node is healthy or not can be determined through scanning by the scanning mode, the node is generally broadcast in the network by each node, and the node broadcasts outside to make other nodes in the local area network know that the node is still early and the state is healthy, so that the accuracy of selecting the node is improved. And judging whether the channel between the node A and the node B is stored in an idle state or not so as to carry out data transmission.
In some embodiments of the present invention, the determining whether the channel is idle includes the following steps: and configuring a directional network allocation vector value for each interface of the laser transmitter and the detector, wherein the directional network allocation vector value is used for setting the predicted occupation time of node transmission, and judging whether the channel is in an idle state or not according to the directional network allocation vector value.
In detail, node a has 6 interfaces, and each interface has a sector angle of 60 °. Thus, each interface maintains a Directed Network Allocation Vector (DNAV) value, which corresponds to a timer, that specifies the time that the medium is expected to be occupied.
In some embodiments of the present invention, when the directional network allocation vector value of the interface is zero, it is determined that the channel is in an idle state, otherwise, the opposite is true.
When the value of DNAV is not zero, the state of the medium is busy, and the virtual carrier monitoring function is realized. Otherwise, if the DNAV value of the node B interface corresponding to the node A is zero, the channel is in an idle state, and the node A returns to the scanning mode at the moment.
In some embodiments of the present invention, the above method for directionally accessing a channel of a deep space optical communication network further includes the following steps, step 3 exchanges RTS/CTS: if the channel is in idle state, judging whether the node A belongs to the vicinity of the node B, if so, selecting an interface with a zero network allocation vector value to send an RTS frame to the node B, otherwise, selecting an interface with a zero network allocation vector value and close to the node B, and sending the RTS frame to the node B through an intermediate node C of the interface.
During configuration, all nodes judge whether to be adjacent to other nodes by using transmitting interfaces distributed circumferentially, so that adjacent nodes of each interface are stored in a neighbor table. Assuming that the channel between node a and node B is idle, node a may then look up whether node B is in its neighbor table. If so, selecting an interface with a value of zero in the DNAV table, and sending an RTS frame to the node B. Otherwise, when node a detects that node B is not in its neighbor table, it sends RTS frame to the intermediate node using the interface direction where DNAV values in other DNAV tables are zero and beneficial for sending to destination node B, which aims to reduce the number of hops required for transmission as much as possible.
In some embodiments of the invention, step 3 further comprises the steps of: after node A sends RTS frame to node B, waiting for node B to reply CTS frame in short frame interval, when node A and node B exchange RTS frame and CTS frame successfully, channel reservation succeeds, otherwise, repeating step 2.
After the node a sends the RTS frame, it waits for the node B to reply to the CTS frame within a Short Interframe Space (SIFS). And the node B receives the RTS frame of the node A, selects an interface which has a DNAV value of zero and corresponds to the direction of the node A and sends a CTS frame. When RTS/CTS is successfully exchanged between the node A and the node B, the channel reservation is successful; otherwise, the channel reservation is failed, and at this time, the step 2 is repeated to judge whether the channel is idle and restart the channel reservation.
In some embodiments of the present invention, the above method for directionally accessing a deep space optical communication network channel further includes the following steps, step 4, data exchange: step 4-1: after the channel reservation is successful, the node a sends data to the node B through an interface close to the node B.
After the channel reservation is successful, the node A selects the nearest 1 interface corresponding to the node B to send data to the contact B. Thereby reducing the number of hops required for transmission.
In some embodiments of the invention, step 4 further comprises the steps of: and when the node B receives the data, selecting an interface close to the node A to reply the ACK frame, when the node A receives the ACK frame, successfully transmitting the data, otherwise, repeating the step 3 if the data transmission fails.
After receiving the data, the node B selects an ACK (Acknowledgement) Acknowledgement frame corresponding to the 4 interfaces of the node a from the neighbor table of each interface of the node B. When the node a receives the ACK frame, this indicates that the data is successfully transmitted this time, otherwise, the data transmission fails, and at this time, step 3 is repeated to reselect the data transmission interface to exchange the RTS/CTS frame.
In some embodiments of the present invention, each node creates a neighbor table, stores interfaces with close distances to other nodes in the neighbor table, and searches for an interface close to a node according to the neighbor table.
The neighbor tables are respectively created and stored through different nodes, so that the interfaces corresponding to the different nodes are conveniently searched for information transmission when the information is transmitted.
In some embodiments of the present invention, the above method for directionally accessing a deep space optical communication network channel further includes the following steps, step 5: and analyzing the simulation result by using the throughput, the fairness, the time delay and the space division multiplexing rate of the channel.
Optionally, the simulation result data is analyzed by using throughput, fairness, time delay and channel space division multiplexing rate, so that the processing efficiency of the deep space communication access protocol can be obtained, and thus the optimal scheme is determined.
As shown in fig. 3, optionally, the node number is n, the simulation time is 100s, and the length of the transmitted data packet is 1000 bytes. In the topological range of 2000 × 2000km, when the topological nodes are 3, 4, 5 and 6 respectively. As shown in fig. 4, the DMAC method compares the throughput with the NDMAC method at different bit stream transmission rates. When 3 and 4, the throughput of the network of the NDMAC method is dominant, and particularly when the value is 3, the advantage is more significant. This is because the number of network topology nodes is small, the network structure is simple, the number of forwarding times of the intermediate node is small, and most of the two nodes can directly communicate with each other. Therefore, the throughput of the network under the NDMAC method is relatively good. This advantage gradually disappears as the number of network nodes increases. When the values are 5 and 6 respectively, the network throughput under the DMAC method is gradually greater than that under the NDMAC method, and when the values are 6, the DMAC method has more obvious advantages, mainly because when the node 0 communicates with the node 6, 6-hop transmission needs to be performed in the middle, and when the DMAC method is used, the laser transmitter faces the direction beneficial to the node 6, the transmission distance is increased through adjusting the power of the transmitter, so that the target receiving node can be reached without 6-hop transmission, and higher throughput and lower time delay are effectively obtained.
As shown in fig. 5 and 6, when the value of the node number is 6, the present application may simulate network throughput and delay at different bit stream transmission rates and different hop counts, and when the transmission hop count is greater than or equal to 3, both the throughput and the delay do not change significantly. In addition, as the number of transmission hops increases, the network throughput gradually decreases and the latency gradually increases. Although the delay and throughput of 1-hop transmission are maximum values, this communication method is not preferable in practical deep space optical communication because the most significant characteristic of deep space optical communication is that the transmission distance is long and the signal is attenuated greatly during the link transmission. Therefore, a relay multi-hop method is required for communication. Taken together, when the value is 6, 2-hop and 3-hop transmissions are preferred and less preferred, respectively.
As shown in fig. 7, in an ideal state, when the simulation time is 100s, the data streams are transmitted simultaneously during the simulation. As shown in fig. 8 and fig. 9, under different data bit stream transmission rates, the obtained network throughput is higher than that of the NDMAC method, and the delay is also significantly lower than that of the NDMAC method. This is mainly because, under the DMAC method, the space division multiplexing rate of the channel is significantly increased, thereby effectively reducing the occurrence of hidden terminals and greatly improving the performance of the entire network. It is clear that the use of the DMAC method in mesh topology is more effective in exploiting the superiority of the method.
To sum up, the method for directionally accessing a deep space optical communication network channel provided by the embodiment of the present application:
the method for directionally accessing the channel of the deep space optical communication network mainly comprises four steps of network initialization, channel idle judgment, Request To Send/Clear To Send (RTS/CTS) and data exchange. In the NS2 simulation environment, MAC protocol experiments are applied to allocate radio channel resources to users competing with each other, that is, how to control a medium to access a channel for data transmission.
The invention designs a deep space optical communication backbone network DMAC access method by combining the deep space optical communication wireless Mesh network structure design and the multi-interface design of nodes, namely, a directional working antenna is adopted to send and receive signals. Compared with an omnidirectional antenna, the MAC protocol supporting the directional antenna can effectively solve the problem of terminal exposure, and meanwhile, the problem of terminal hiding is greatly reduced. The directional antennas actually separate the space, and separate the possible collisions in the omnidirectional mode in the transmission direction, so that not only can the interference area be reduced, thereby improving the space division multiplexing rate of the channel, but also the transmission hop count and the grouping collision of the data packets can be reduced, the network performance is improved, and the node throughput is effectively improved.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. The apparatus embodiments described above are merely illustrative, and for example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, functional modules in the embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.
The above-described functions, if implemented in the form of software functional modules and sold or used as a separate product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the above-described method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
It will be evident to those skilled in the art that the present application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Claims (10)
1. A method for directionally accessing a deep space optical communication network channel is characterized by comprising the following steps,
step 1, network initialization:
step 1-1: configuring a multi-interface model of deep space optical communication in an NS2 simulation environment;
step 1-2: establishing a deep space optical communication channel transmission model according to a mathematical transmission model of a deep space optical communication link, and adding the deep space optical communication link transmission model in a Two-Rayground model in NS2 simulation software;
step 1-3: the method comprises the steps that a plurality of nodes are configured through NS2 simulation software, each node is initialized, each node is configured with 1 detector and a plurality of laser transmitters, the detectors are used for detecting and receiving signals sent by the laser transmitters, the laser transmitters are uniformly distributed around the circumference of the node, and when the nodes communicate, the closer laser transmitters are selected to transmit the signals.
2. The deep space optical communication network channel directional access method according to claim 1, further comprising the following steps, step 2, the node performs communication: all nodes are in a scanning mode, a source node A and a destination node B are set, whether a channel is in an idle state or not is judged, if not, the node A sends data to the node B, and if not, the scanning mode is returned.
3. The deep space optical communication network channel directional access method according to claim 2, wherein the step of judging whether the channel is idle comprises the following steps: and configuring a directional network distribution vector value for each interface of the laser emitter and the detector, wherein the directional network distribution vector value is used for setting the expected occupied time of node transmission, and judging whether the channel is in an idle state or not according to the directional network distribution vector value.
4. A deep space optical communication network channel directional access method as claimed in claim 2, characterized in that, when the directional network allocation vector value of the interface is zero, the channel is determined to be in idle state, otherwise, the opposite is true.
5. The deep space optical communication network channel directional access method according to claim 2, further comprising the following steps, step 3 exchanges RTS/CTS: if the channel is in idle state, judging whether the node A belongs to the vicinity of the node B, if so, selecting an interface with a zero network allocation vector value to send an RTS frame to the node B, otherwise, selecting an interface with a zero network allocation vector value and close to the node B, and sending the RTS frame to the node B through an intermediate node C of the interface.
6. The deep space optical communication network channel directional access method as claimed in claim 2, wherein the step 3 further comprises the steps of: after node A sends RTS frame to node B, waiting for node B to reply CTS frame in short frame interval, when node A and node B exchange RTS frame and CTS frame successfully, channel reservation succeeds, otherwise, repeating step 2.
7. The deep space optical communication network channel directional access method according to claim 6, further comprising the following steps, step 4 data exchange: step 4-1: after the channel reservation is successful, the node a sends data to the node B through an interface close to the node B.
8. The deep space optical communication network channel directional access method of claim 7, wherein the step 4 further comprises the steps of: and when the node B receives the data, selecting an interface close to the node A to reply the ACK frame, when the node A receives the ACK frame, successfully transmitting the data, otherwise, repeating the step 3 if the data transmission fails.
9. A deep space optical communication network channel directional access method according to any one of claims 5 to 8, characterized in that each node creates a neighbor table, stores the interfaces of other nodes with close distance to the neighbor table, and looks up the interface close to the node according to the neighbor table.
10. The deep space optical communication network channel directional access method according to claim 2, further comprising the steps of, step 5: and analyzing the simulation result by using the throughput, the fairness, the time delay and the space division multiplexing rate of the channel.
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