CN112217728A - Satellite channel hybrid access method based on pre-allocation and on-demand reservation - Google Patents
Satellite channel hybrid access method based on pre-allocation and on-demand reservation Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L45/00—Routing or path finding of packets in data switching networks
- H04L45/12—Shortest path evaluation
- H04L45/121—Shortest path evaluation by minimising delays
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L45/00—Routing or path finding of packets in data switching networks
- H04L45/02—Topology update or discovery
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L45/00—Routing or path finding of packets in data switching networks
- H04L45/30—Routing of multiclass traffic
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/08—Access restriction or access information delivery, e.g. discovery data delivery
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/04—Wireless resource allocation
- H04W72/044—Wireless resource allocation based on the type of the allocated resource
- H04W72/0446—Resources in time domain, e.g. slots or frames
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
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- H04W72/30—Resource management for broadcast services
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- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/56—Allocation or scheduling criteria for wireless resources based on priority criteria
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W84/00—Network topologies
- H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
- H04W84/04—Large scale networks; Deep hierarchical networks
- H04W84/06—Airborne or Satellite Networks
Abstract
The invention provides a satellite channel hybrid access method based on pre-allocation and reservation on demand, wherein a node in an air network is accessed to a satellite channel, a time division multiple access and a frequency division multiple access hybrid access mode based on the pre-allocation of the satellite channel and the reservation on demand of resources, and is oriented to a task demand and an air-to-air network access strategy based on node position information, so that the optimal access selection control of the wide area range to the whole network members of the air-to-air network can be realized, and network resources are saved; when the air node moves in a long distance, the topology management of the network can be realized, the blocking rate and the time delay are effectively reduced, the service quality of each service is ensured, and the channel utilization rate is improved.
Description
Technical Field
The invention belongs to the technical field of aerospace information networks, and mainly relates to cross-subnet remote communication of an air node through an access satellite, in particular to a hybrid access technology for accessing a satellite channel based on pre-allocation of a satellite channel and reservation of resources as required, which is used for aerospace information networks.
Background
The air-space information network is an integrated network system of land, sea, air and day, and has autonomous information acquisition, storage, processing and distribution capabilities. The access control technology is a precondition for providing efficient and rapid service for the air information network, and is a key technology for air access. The aerospace access system is a key component of aerospace information networks and is a key place in aerospace information networks for direct connection with terminal users. The aerospace access system aims at various access requirements of aerospace information network terminals, and solves the problems of switching generated in the aerospace information network communication process and dynamic scheduling and allocation of wireless channel resources.
The aerospace information network has multiple characteristics: the network complexity means that the network system is huge, the structure is complex and the integrity is outstanding; high dynamic property, which means that the user terminal and the transfer node move ceaselessly; the sudden event refers to large number of users, high sudden service and short communication time; the performance is unstable, namely the transmission time is prolonged, the error code is high, the uplink and the downlink are asymmetric, and the influence of the environment is large; the heterogeneity of the network structure means that the networking modes of all layers of the aerospace network are different, and the heterogeneity exists in the layers and among the layers. According to the characteristics and the practical application target, the system structure design requirement of the aerospace information network can be summarized as follows: large capacity, requiring a network system with large capacity, ultra high speed and ultra wide band; the safety is high, the overall safety coefficient of the network is required to be high, the interference resistance is strong, and the dynamic survivability and the robustness are good; the network has the characteristic of high intellectualization, namely has the self-organization independent operation capability and the capability of mutual communication and cooperation among various subsystems, and can be quickly linked and seamlessly accessed; and the topology reconstruction performance can carry out rapid network reconstruction according to the reduction of the nodes due to damage and the increase of the nodes due to reissue.
The functions of the existing satellite systems (such as a detection satellite and a navigation satellite) in China are different and are isolated from each other, and the satellite systems are not communicated with each other; and the same type of satellite (such as several reconnaissance satellites) is relatively independent, so that mutual communication and cooperative transmission are difficult to carry out. At present, the satellite reconnaissance system in China usually adopts overhead transmission to transmit observation images back to the ground, so that the response speed is slow, and the aerial dynamic decision is difficult to realize. And real-time interconnection between unmanned aerial vehicle clusters can not be realized due to factors such as high maneuverability, distance and the like, so that the actions are difficult to coordinate and consistent, and dynamic task allocation is completed in time. Therefore, the reasonable and efficient access control technology has great practical significance for aerospace information networks and national defense construction.
The aerospace information network is a huge, complex communication network with high technical and performance requirements, and research on an access network of the aerospace information network only aims at how to obtain the maximum utilization rate of network resources, so that the aerospace information network cannot be understood by using a quality assurance (QoS) concept in a common network. The important point of the aerospace information network access system research is as follows: technically, how to access different types and requirements of user terminals, particularly how to access terminals moving quickly, and how to effectively form an integrated access network by sub access systems in various geographic positions and adjacent space access aircrafts are considered; in terms of strategy, the traditional user access strategy, such as multiple access based on fixed allocation, random access, access based on QoS and the like, is not directly applicable any more, the access strategy must be matched with a unified strategy made by a decision unit according to comprehensive factors of an application scene, and the access strategy is embodied in each access technical link. The integrated management of access points (low orbit constellation, middle orbit constellation and high orbit constellation), the quick access management of high-speed aircrafts and the high intelligent access strategy are the core of the research of the aerospace information network high dynamic intelligent access system. The aerospace information network high dynamic intelligent access system requires that a legal user terminal can access the aerospace information network in time and in the most consistent way on the whole benefits, so as to obtain corresponding services, which is a research target of the aerospace information network access system.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a hybrid access mode that nodes in an air network access satellite channels, time division multiple access and frequency division multiple access based on pre-distributed satellite channels and reserved resources as required under a constellation system of a large elliptic orbit satellite, and an air-to-air network access strategy facing to task requirements and based on node position information, so that the optimal access selection control of the wide area range to the whole network members of the air-to-air network can be realized, and network resources are saved; when the air node moves in a long distance, the topology management of the network can be realized, the blocking rate and the time delay are effectively reduced, the service quality of each service is ensured, and the channel utilization rate is improved.
The technical scheme adopted by the invention for solving the technical problem comprises the following steps:
step 4, the aerial node occupies the service time slot according to the response message of the large elliptic orbit satellite to send the service packet;
step 5, if the large elliptic orbit satellite has no available idle time slot temporarily, and the aerial node fails to receive a response message of successful reservation in a time frame period, the application is considered to fail; if the sending requirement is still not met, sending a service time slot for applying reservation to the large elliptic orbit satellite in the next frame; and the hybrid access of the air node to the satellite channel based on the pre-allocated satellite channel and the reserved resource according to the requirement is completed.
The air node applies for the reserved service time slot to the large elliptic orbit satellite in the reserved time slot, and the method comprises the following steps: the air node of each sub network occupies a fixed reservation time slot in each frame, and the air node detects the number of data packets in the queue at the moment when the own reservation time slot in each frame arrives; and if the number is not 0, establishing a time slot reservation packet, writing a source address, a destination address, the geographical position information of the node and the priority of the data packet, and sending out the time slot reservation position 1.
The method for dividing the time slot after the large elliptic orbit satellite receives the application of all the nodes comprises the following steps:
(3a) firstly checking the time slot reservation position and the geographical position information of a source node in a time slot reservation package, and then recording the priority of a node applying for reserving a time slot in a specified geographical position into an array according to the ID number of the node;
(3b) when the response time slot arrives, the large elliptic orbit satellite allocates the service time slot according to the time slot allocation algorithm, and the method comprises the following steps:
(3b1) firstly, inquiring an array, recording the number of nodes needing to be reserved in the nodes of the subnet 1, if the number of the nodes is not more than 10, sequentially dividing 10 dynamic time slots into each node according to the sequence of high priority, low priority and reserved node ID number from small to large, wherein each node has 1 time slot;
(3b2) if the number of nodes to be reserved in the subnet 1 is more than 10 and the number of the high-priority nodes is less than 10, the requirement of the high-priority nodes is met, and then the rest time slots are allocated to the low-priority nodes;
(3b3) if the number of the high priorities is more than 10, sequentially dividing 10 dynamic time slots into 10 high-priority nodes according to the descending order of the ID numbers of the nodes;
(3b4) and creating a time slot reservation response packet, sending the time slot reservation response packet to a sender corresponding to the subnet 1, and broadcasting the message to the nodes of the subnet 1.
(3b5) And repeating the steps (3b1) - (3b4), respectively dividing the time slots for other subnets, and respectively broadcasting the response packets to the nodes of other subnets.
The air node occupies the service time slot according to the response message of the large elliptic orbit satellite to send the service packet, and the method comprises the following steps:
(4a) after receiving the time slot reservation response packet, the air node checks whether the response packet has the own node ID number or not, and if the response packet does not indicate that the service time slot is not reserved successfully; if the service time slot reservation is successful, the corresponding service time slot number is continuously checked;
(4b) calculating the time of the node occupying the service time slot according to the service time slot number;
(4c) when the time of occupying the service time slot by the node is calculated in the step (4b), calculating the packet sending quantity of one time slot according to the length of the service time slot and the packet sending rate, then counting the quantity of the packets queued in the queue at the moment, and taking a smaller value as the quantity of the packets sent by occupying the service time slot at this time;
(4d) the packets queued in the queue are sequentially transmitted to the sender on a first-in-first-out basis.
The invention has the beneficial effects that:
1) the invention is based on pre-distributing satellite channel and reserving resource to access satellite channel according to need, that is, when some node has service group to send, it sends the request of reserving service time slot in its own fixed time slot. The method can eliminate the retransmission caused by unsuccessfully sending the reservation request due to collision, reduce the blocking rate, thereby obviously improving the probability of successful delivery of the reservation request and reducing the consumption of network space resources by service transmission, and has no obvious influence on the service transmission requirement of each node and network overhead as far as possible.
2) The invention adopts a hybrid access mode combining time division multiple access and frequency division multiple access, each sub-network respectively occupies a frequency point to communicate with the satellite, and the nodes in each sub-network access the satellite in a time division multiple access mode to transmit packets to carry out cross-sub-network communication. Not only saves network frequency band resources and improves channel utilization rate, but also can realize optimal access selection control of wide area range to all members of the air-space network; and when the air node moves in a long distance, the topology management of the network can be realized, and the end-to-end time delay of various messages is reduced under the condition of not influencing the throughput.
3) Based on the service priority and the node ID number, the invention considers the request with low priority only when meeting the request with high priority as much as possible; the requests with the same priority are divided into time slots from small to large according to the ID numbers of the nodes. Namely, firstly, the method provides guarantee for the service quality of the high-priority service, and can be applied to various emergency environments or emergency situations.
4) The invention adopts the service rule of the depletion system, can send out the newly arrived packet between the appointment period and the transmission period in time, obviously reduce the time delay of each service and save the space resource of the node.
Drawings
FIG. 1 is a schematic overall flow diagram of the present invention;
FIG. 2 is a flow chart of a dynamic time slot allocation algorithm of the present invention;
fig. 3 is a diagram illustrating a superframe format of TDMA in the present invention;
fig. 4 is a diagram illustrating access delay statistics (time averaged) for an air node in an embodiment of the present invention;
fig. 5 is a schematic diagram of end-to-end delay statistics (time-averaged) of traffic in an embodiment of the present invention;
FIG. 6 is a schematic diagram of network throughput statistics for an over-the-air subnet in an embodiment of the invention;
fig. 7 is a schematic diagram of overhead statistics of an air subnet access control protocol in an embodiment of the present invention.
Detailed Description
The present invention will be further described with reference to the following drawings and examples, which include, but are not limited to, the following examples.
The invention relates to a hybrid access technology for accessing a satellite channel based on pre-allocation of the satellite channel and reservation of resources as required, which realizes the technical scheme of the invention and comprises the following steps:
step 4, the aerial node occupies the service time slot according to the response message of the large elliptic orbit satellite to send the service packet;
and 5, if the large oval node has no available idle time slot temporarily, and the air node fails to receive a response message of successful reservation in a time frame period, considering that the application fails. And at the moment, if the sending requirement is still not met, sending the time slot for applying for the reservation service to the large elliptic orbit satellite in the next frame. And the hybrid access of the node to the satellite channel based on pre-allocation of the satellite channel and reservation-on-demand resource is completed.
In order to reduce the influence of blocking and the like caused by collision retransmission, the invention allocates fixed time slots to each air node, when a certain node has service grouping to be sent, the node can send a request for reserving the service time slot in the fixed time slot of the node, thereby obviously improving the probability of success of sending the reservation request and reducing the access time delay of each air node. Compared with the traditional fixed time division multiple access technology, the invention is oriented to the task requirement and saves the network resources. And because the reservation request message is not large, the total length of the fixed time slot subframe is not long, and the access method of the invention reduces the blocking rate and reduces the consumption of network space resources by service transmission as far as possible under the condition of not influencing the service transmission requirement of each node and not obviously increasing the overhead.
The invention is also realized in that: the large elliptic orbit satellite in the step 1 grasps the propagation delay from all nodes in the whole network to the large elliptic orbit satellite, and acquires the propagation delay from each node to each large elliptic satellite through information interaction between the elliptic satellites, comprising the following steps:
(1a) all nodes of the whole network send hello packets to a large elliptic orbit satellite at intervals;
(1b) calculating the propagation delay from each node to the large elliptic orbit satellite according to the hello packet, recording the propagation delay, and establishing a local propagation delay information table;
(1c) after the local information table of the large elliptic orbit satellite is finished, the local information table is respectively sent to other large elliptic orbit satellites, so that a whole network propagation delay information table is established.
For the same air node, the propagation delay to the large elliptic orbit satellite is basically determined by the distance, and the method provides a judgment basis for selecting a path with the shortest propagation delay in the routing decision process.
The invention is also realized in that: when a certain node has a service to be sent in step 2, the node can apply for a reserved service time slot to a large elliptic orbit satellite in the reserved time slot, and the method comprises the following steps:
(2a) the air node of each sub network occupies a fixed reservation time slot in each frame, and the air node detects the number of data packets in the queue at the moment when the own reservation time slot in each frame arrives;
(2b) and if the number is not 0, creating a time slot reservation packet, writing a source address (the ID of the node), a destination address (the selected large elliptic orbit satellite), the geographical position information of the node and the priority of the data packet, and sending out the time slot reservation position 1.
The invention is oriented to task requirements, namely when a certain node has service packets to be sent, a request for reserving service time slots is sent in a fixed time slot of the node. In the traditional access mode of fixed time division multiple access, nodes transmit services in the fixed time slots allocated by the nodes, although the access time delay is reduced, the nodes still occupy the time slots when low traffic or even no services need to be transmitted, and network resources are wasted. In the invention, the node does not transmit the service in the fixed time slot, and only sends the reservation request when needed, thereby greatly shortening the sub-frame length of the fixed time slot; and because each node occupies a fixed time slot, the retransmission caused by unsuccessfully sending the reservation request due to collision can be eliminated, and the blocking rate is reduced, so that the probability of successful sending of the reservation request is obviously improved, the consumption of network space resources by service transmission is reduced, and the service transmission requirements of each node and the network overhead are not obviously influenced as much as possible.
The invention is also realized in that: the dividing of the time slots after the large elliptic orbit satellite receives the applications of all the nodes comprises the following steps:
(3a) firstly checking the time slot reservation position and the geographical position information of a source node in a time slot reservation package, and then recording the priority of a node applying for reserving a time slot in a specified geographical position into an array according to the ID number of the node;
(3b) when the response time slot arrives, the large elliptic orbit satellite allocates the service time slot according to the time slot allocation algorithm, and the method comprises the following steps:
(3b1) firstly, inquiring an array, recording the number of nodes needing to be reserved in the nodes of the subnet 1, if the number is not more than 10 (only 10 dynamic time slots are available in each frame in the simulation), sequentially dividing 10 dynamic time slots into each node according to the sequence of high priority first and low priority later and the sequence of reserved node ID numbers from small to large, wherein each node has 1 time slot;
(3b2) if the number of nodes to be reserved in the subnet 1 is more than 10 and the number of the high-priority nodes is less than 10, the requirement of the high-priority nodes is met, and then the rest time slots are allocated to the low-priority nodes;
(3b3) if the number of the high priorities is more than 10, sequentially dividing 10 dynamic time slots into 10 high-priority nodes according to the descending order of the ID numbers of the nodes;
(3b4) and creating a time slot reservation response packet, sending the time slot reservation response packet to a sender corresponding to the subnet 1, and broadcasting the message to the nodes of the subnet 1.
(3b5) Repeating the steps (3b1) - (3b4), dividing time slots for other subnets, and broadcasting response packets to nodes of subnet 2 and subnet 3.
In the invention, each aerial subnet is set to occupy different frequency points and large elliptic orbit satellite nodes for communication, so that the communication behavior of each subnet and the large elliptic orbit satellite is 'simultaneous' in time, and as all members in the whole network use unique identification marks (namely the node ID numbers are different), all time slot reservation packets received by the large elliptic orbit satellite in a frame can record the priority of the time slot reservation packets into the same array according to the node ID numbers. When dividing service time slots for each subnet, the large elliptic orbit satellite firstly meets the request with high priority as much as possible and considers the request with low priority based on the service priority and the node ID number; the requests with the same priority are divided into time slots from small to large according to the ID numbers of the nodes. Because the method adopts a mixed access mode of time division multiple access and frequency division multiple access, the access delay and the end-to-end delay of the service are obviously reduced, and all indexes of the high-priority service are ensured to reach the standard at first.
The invention is also realized in that: step 4, the air node occupies the service time slot according to the response message of the large elliptic orbit satellite to send the service packet, which comprises the following steps:
(4a) after receiving the time slot reservation response packet, the air node checks whether the response packet has the own node ID number or not, and if the response packet does not indicate that the service time slot is not reserved successfully; if the service time slot reservation is successful, the corresponding service time slot number is continuously checked;
(4b) calculating the time of the node occupying the service time slot according to the service time slot number;
(4c) when the time of occupying the service time slot by the node is calculated in the step (4b), calculating the packet sending quantity of one time slot according to the length of the service time slot and the packet sending rate, then counting the quantity of the packets queued in the queue at the moment, and taking a smaller value as the quantity of the packets sent by occupying the service time slot at this time;
(4d) the packets queued in the queue are sequentially transmitted to the sender on a first-in-first-out basis.
The invention adopts the service rule of the depletion system, namely, all the arriving packets in the memory are transmitted as far as possible in the service time slot occupied by the node. Therefore, the newly arrived packet between the reservation period and the transmission period can be prevented from being transmitted after waiting for the next frame to reserve the time slot again in the queue, the end-to-end time delay is obviously reduced, and the space resource of the node is saved.
The embodiment illustrates the implementation process of the present invention through simulation of a specific scenario, and refer to fig. 1.
1. Simulation scenario
Suppose the network scenario is 2000km × 2000km, and there are 15 nodes in the network. The satellite communication system comprises 6 large elliptic orbit satellites and three air subnetworks, wherein each subnetwork has 3 nodes. The air subnet members are distributed within a range of 400km x 400 km. The sending rate of the air node is 200kbps, and the receiving rate is 2 Mbps; the corresponding large elliptical orbit satellite transmission rate is 2Mbps and the reception rate is 200 kbps. Different subnetworks communicate with the large elliptic orbit satellite in a frequency division mode, and members in the same subnet access the large elliptic orbit satellite to communicate in a time division mode so as to realize cross-subnet service transmission. The communication frequency point of the subnet I and the large elliptic orbit satellite is 100MHz, and the bandwidth is 10 kHz; the communication frequency point of the subnet II and the large elliptic orbit satellite is 110MHz, and the bandwidth is 10 kHz; the communication frequency point of the subnet III and the large elliptic orbit satellite is 120MHz, and the bandwidth is 10 kHz; the frame length of each frame of time division multiple access is 0.765s, and the format of the superframe is shown in figure 3. The time slot reservation packet is 80 bits, the time slot reservation response packet is 110 bits, and the data packet is 1024 bits. The traffic generates 1 packet every 3 s. Simulation software OPNET-Modeller is used for simulating the access delay of the air node, the end-to-end delay of the service, the packet loss rate of on-satellite processing queuing and scheduling, the network throughput of the air sub-network and the overhead statistics of the air sub-network access control protocol, and the simulation time is 2 hours.
2. Simulation concrete implementation
The invention relates to a hybrid access technology for accessing a satellite channel based on pre-allocation of the satellite channel and reservation of resources according to needs, which comprises the following steps:
(1a) all nodes in the whole network send hello packets to a large elliptic orbit satellite every 5s, and the current time is written in the hello packets as sending time during sending;
(1b) after receiving a hello packet sent by a node, the large elliptic orbit satellite subtracts the sending time in the hello packet from the current time to calculate the propagation delay from each node to the hello packet, records the ID number of the source node and the corresponding propagation delay, and establishes a local propagation delay information table;
(1c) after the local information table of the large elliptic orbit satellite is finished, sending the local information table to other 5 large elliptic orbit satellites for information interaction, and thus establishing a whole network propagation delay information table;
(1d) the large elliptic orbit satellite broadcasts the whole network propagation delay information table, and each node selects a large elliptic satellite with the shortest propagation delay as a subsequent access point for sending service messages.
Compared with the air subnetworks, the large elliptic orbit satellite is far away from the ground, so that the members of the three air subnetworks basically select the same large elliptic orbit satellite at the same time. In the step 1, the shortest time delay priority principle is adopted to select the accessed satellite, so that the access time delay and the end-to-end time delay can be reduced.
And step 2, dividing one frame into a reserved time slot subframe, a response time slot subframe and a service time slot subframe, and when a certain node has a service to be sent, the node can apply for a reserved service time slot to the large elliptic orbit satellite selected in the step 1 in the reserved time slot. The method specifically comprises the following steps:
(2a) each air node of each sub network occupies a fixed reserved time slot in each frame, the reserved time slot is calculated by a node ID, and the method specifically realizes the following steps:
(2a1) in the scene, each air subnet is set to contain 10 nodes at most, the ID of each node is different and is a continuous number of 10, and the simulation only randomly places 3 nodes for each subnet;
(2a2) the fixed reservation time slot number of each node in the subnet is the relative size of the current node ID number to the minimum ID number in the subnet, namely, the fixed reservation time slot number is obtained by taking the remainder of the minimum ID number in the subnet according to the node ID number;
(2a3) the node is the remainder obtained in the last step and multiplied by the length of the reserved time slot in the fixed reserved time slot of a frame, and the length of each reserved time slot is set to be 0.0005s in the simulation;
(2b) the air node detects the number of data packets in the queue at the moment when the reserved time slot of the air node arrives in each frame;
(2c) if the number is not 0, a time slot reservation packet is created, a source address (the ID of the node), a destination address (a selected large elliptic orbit satellite), geographical position information of the node and the priority of a data packet are written, and the time slot reservation position 1 is sent out; if the number is 0, no processing is performed, and (2b) and (2c) are repeated when the fixed reservation slot of the next frame arrives, and the packet format of the slot reservation packet is shown in table 1.
Table 1 packet format for slot reservation packets
In the simulation, when a certain node has a service packet to be sent, a request for reserving a service time slot is sent in a fixed time slot of the node. Because the node does not transmit service in the fixed time slot, and only sends a reservation request when needed, the length of the sub-frame of the fixed time slot can be greatly shortened; and because each node occupies a fixed time slot, the retransmission caused by unsuccessfully sending the reservation request due to collision can be eliminated, and the blocking rate is reduced, so that the probability of successful delivery of the reservation request is obviously improved, the consumption of network space resources by service transmission is reduced, and the service transmission requirements of each node are not obviously influenced as much as possible.
And 3, after receiving the applications of all the nodes, the large elliptic orbit satellite judges whether the own time slot resource can meet the request, and broadcasts a message to inform the air nodes after dividing the time slots. The method specifically comprises the following steps:
(3a) firstly checking the time slot reservation position and the geographical position information of a source node in a time slot reservation package, and then recording the priority of a node applying for reserving a time slot in a specified geographical position into an array according to the ID number of the node;
(3b) when the response time slot arrives, the large elliptic orbit satellite allocates the service time slot according to the time slot allocation algorithm, and preferentially meets the requirement of high-priority service, referring to fig. 2, the method comprises the following steps:
(3b1) firstly, inquiring an array, recording the number of nodes needing to be reserved in the nodes of the subnet 1, if the number is not more than 10 (only 10 dynamic time slots are available in each frame in the simulation), sequentially dividing 10 dynamic time slots into each node according to the sequence of high priority first and low priority later and the sequence of reserved node ID numbers from small to large, wherein each node has 1 time slot;
(3b2) if the number of nodes to be reserved in the subnet 1 is more than 10 and the number of the high-priority nodes is less than 10, the requirement of the high-priority nodes is met, and then the rest time slots are allocated to the low-priority nodes;
(3b3) if the number of the high priorities is more than 10, sequentially dividing 10 dynamic time slots into 10 high-priority nodes according to the descending order of the ID numbers of the nodes;
(3b4) creating a time slot reservation response packet, writing the ID number of the application node and the corresponding dynamic time slot number into a packet domain, sending the packet to a sender corresponding to the subnet 1, broadcasting the message to the nodes of the subnet 1, and referring to table 2 for the packet format of the time slot reservation response packet.
Table 2 packet format for slot reservation reply packet
(3b5) Repeating the steps (3b1) - (3b4), dividing time slots for other subnets, and broadcasting response packets to nodes of subnet 2 and subnet 3.
In the simulation, only 3 nodes are placed in each subnet, so that the condition that the number of reserved nodes is more than 10 does not occur. In the invention, each aerial subnet is set to occupy different frequency points and large elliptic orbit satellite nodes for communication, so that the communication behavior of each subnet and the large elliptic orbit satellite is 'simultaneous' in time, and as all members in the whole network use unique identification marks (namely the node ID numbers are different), all time slot reservation packets received by the large elliptic orbit satellite in a frame can record the priority of the time slot reservation packets into the same array according to the node ID numbers. When dividing service time slots for each subnet, the large elliptic orbit satellite firstly meets the request with high priority as much as possible and considers the request with low priority based on the service priority and the node ID number; the requests with the same priority are divided into time slots from small to large according to the ID numbers of the nodes. Because the method adopts a mixed access mode of time division multiple access and frequency division multiple access, the access delay and the end-to-end delay of the service are obviously reduced, and all indexes of the high-priority service are ensured to reach the standard at first.
Step 4, the aerial node occupies the service time slot according to the response message of the large elliptic orbit satellite to send the service packet;
(4a) after receiving the time slot reservation response packet, the air node checks whether the response packet has the own node ID number or not, and if the response packet does not indicate that the service time slot is not reserved successfully; if the service time slot reservation is successful, the corresponding service time slot number is continuously checked;
(4b) calculating the time of the node occupying the service time slot according to the service time slot number; the specific calculation method is as follows:
(4b1) if a frame is 0.765s, the current starting time of the frame and the current frame can be calculated;
(4b2) setting the length of each dynamic service time slot to be 0.026s in the simulation, and calculating the 0.505s of the service time slot subframe in each frame after the frame starts if 10 dynamic time slots are provided;
(4b3) the time that the node occupies the service time slot is the sum of the starting time of the frame plus 0.505s and the sum of the service time slot number multiplied by the length of the dynamic service time slot;
(4c) when the time of occupying the service time slot by the node is calculated in the step (4b), calculating the packet sending quantity of one time slot according to the length of the service time slot and the packet sending rate, then counting the quantity of the packets queued in the queue at the moment, taking a smaller value as the quantity of sending the packets occupying the service time slot at the moment, and referring to a table 3 for the packet format of the data packet;
table 3 packet format for data packets
(4d) The packets queued in the queue are sequentially transmitted to the sender on a first-in-first-out basis.
The invention adopts the service rule of the depletion system, namely, all the arriving packets in the memory are transmitted as far as possible in the service time slot occupied by the node. Therefore, the newly arrived packet between the reservation period and the transmission period can be prevented from being transmitted after waiting for the next frame to reserve the time slot again in the queue, the end-to-end time delay is obviously reduced, and the space resource of the node is saved.
And 5, if the large oval node has no available idle time slot temporarily, and the air node fails to receive a response message of successful reservation in a time frame period, considering that the application fails. And at the moment, if the sending requirement is still not met, sending the time slot for applying for the reservation service to the large elliptic orbit satellite in the next frame. And the hybrid access of the node to the satellite channel based on pre-allocation of the satellite channel and reservation-on-demand resource is completed.
Simulation results and analysis
Fig. 4 is the access delay statistics (time averaged) for the air node in this example. Wherein the abscissa is time, and the ordinate is access delay of the air node. The access delay refers to the time required by a node which needs to send data service from the initiation of an access request to the time when the node sends service data. As can be seen from the figure: the access time delay of the air node tends to 0.88s under the time average, is less than 1 second and is very short.
Figure 5 is the end-to-end delay statistics (time averaged) for the traffic in this example. Wherein the abscissa is time and the ordinate is end-to-end delay of the service. End-to-end latency refers to the time required for a message to originate from an air node to successfully arrive at another air node. As can be seen from the figure: the end-to-end delay of the message tends to be 0.4s, less than 0.5 s, on time average, and is very short.
Fig. 6 is a network throughput statistics for the over-the-air subnets in this example. Wherein the abscissa is time, the ordinate is the network throughput of the air subnet, and the unit is bit/s. As can be seen from the figure: the network throughput of the over-the-air subnets tends to 9200 bit/s.
Figure 7 is an overhead statistic of the air subnet access control protocol in this example. Wherein the abscissa is time and the ordinate is the ratio. The overhead of the access control protocol refers to the ratio of the number of bits of the reservation packet plus the response packet to the total number of bits of all packets (including the reservation packet, the response packet, and the data packet) in a frame. As can be seen from the figure: overhead of the air subnet access control protocol tends to be 16%.
The advantages of the access method are mainly embodied in five aspects: 1. the invention adopts the shortest time delay priority principle to select the accessed large elliptic orbit satellite, can reduce the propagation time delay of the message, and further reduce the access time delay of the air node and the end-to-end time delay of the service; 2. the invention is oriented to task requirements, namely when a certain node has service packets to be sent, a request for reserving service time slots is sent in a fixed time slot of the node. Not only can eliminate retransmission caused by unsuccessfully sending the reservation request due to collision, and reduce the blocking rate, but also reduce the consumption of resources such as network time, space and the like by service transmission; 3. the invention adopts a hybrid access mode combining time division multiple access and frequency division multiple access, each sub-network respectively occupies a frequency point to communicate with the satellite, and the nodes in each sub-network access the satellite in a time division multiple access mode to transmit packets to carry out cross-sub-network communication. The time and frequency band resources of the network are fully utilized, the channel utilization rate is improved, and no waste is caused; 4. the invention meets the request of high priority as much as possible, only considers the request of low priority, namely provide the guarantee for the service quality of the high priority business at first, can apply to all kinds of emergency environment or under the emergency situation; 5. the invention adopts the service rule of the depletion system, can send out the newly arrived packet between the appointment period and the transmission period in time, obviously reduce the time delay of each service and save the space resource of the network.
Briefly, the present invention discloses a hybrid access method for accessing a node in an air network to a satellite channel, a time division multiple access and a frequency division multiple access based on pre-allocated satellite channels and resources reserved as required under a constellation system of a large elliptic orbit satellite, which comprises the following steps: the time slot is divided into a fixed time slot, a response time slot and a dynamic time slot, different air subnets communicate with the large elliptic orbit satellite in a frequency division mode, and members in the same subnet access the large elliptic orbit satellite in a time division mode to communicate; each aerial node selects a large elliptic satellite with the shortest propagation delay as an access point for subsequently sending service messages according to the shortest delay priority principle, and when the node generates service packets, a time slot reservation packet can be sent to the large elliptic orbit satellite in a fixed time slot; after receiving the time slot reservation packet, the large elliptic orbit satellite allocates service time slots to reservation nodes of each sub-network according to a time slot allocation algorithm (based on priority and node ID), writes a time slot reservation response packet and broadcasts the packet to each sub-network; and finally, the aerial node occupies the service time slot according to the response message of the large elliptic orbit satellite to send the service packet. The invention belongs to the technical field of aerospace information networks, and can realize optimal access selection control of wide-area-range air-space network members; when the air node moves in a long distance, the topology management of the network can be realized, the blocking rate is effectively reduced, various time delays are reduced, the service quality of each service is ensured, the channel utilization rate is improved, and the method can be used for an air-to-air information network.
Claims (4)
1. A satellite channel hybrid access method based on pre-allocation and on-demand reservation is characterized by comprising the following steps:
step 1, the large elliptic orbit satellite grasps the propagation delay from all air nodes of the whole network to the large elliptic orbit satellite, acquires the propagation delay from each air node to each large elliptic orbit satellite through information interaction between the large elliptic orbit satellites, then broadcasts the information, and each air node selects one large elliptic orbit satellite with the shortest propagation delay as an access point for subsequently sending service information;
step 2, dividing a frame into a reserved time slot subframe, a response time slot subframe and a service time slot subframe, and when a certain air node has a service to be sent, applying for a reserved service time slot for the large elliptic orbit satellite selected in the step 1 in the reserved time slot by the air node;
step 3, after receiving the applications of all the nodes, the large elliptic orbit satellite judges whether the own time slot resources can meet the requests, and broadcasts a message to inform the air nodes after dividing the time slots;
step 4, the aerial node occupies the service time slot according to the response message of the large elliptic orbit satellite to send the service packet;
step 5, if the large elliptic orbit satellite has no available idle time slot temporarily, and the aerial node fails to receive a response message of successful reservation in a time frame period, the application is considered to fail; if the sending requirement is still not met, sending a service time slot for applying reservation to the large elliptic orbit satellite in the next frame; and the hybrid access of the air node to the satellite channel based on the pre-allocated satellite channel and the reserved resource according to the requirement is completed.
2. The pre-allocation and on-demand reservation-based satellite channel hybrid access method of claim 1, wherein: the air node applies for the reserved service time slot to the large elliptic orbit satellite in the reserved time slot, and the method comprises the following steps: the air node of each sub network occupies a fixed reservation time slot in each frame, and the air node detects the number of data packets in the queue at the moment when the own reservation time slot in each frame arrives; and if the number is not 0, establishing a time slot reservation packet, writing a source address, a destination address, the geographical position information of the node and the priority of the data packet, and sending out the time slot reservation position 1.
3. The hybrid access method of satellite channels based on pre-allocation and on-demand reservation according to claim 1, wherein the large elliptic orbit satellite divides the time slot after receiving the application of all nodes, comprising the steps of:
(3a) firstly checking the time slot reservation position and the geographical position information of a source node in a time slot reservation package, and then recording the priority of a node applying for reserving a time slot in a specified geographical position into an array according to the ID number of the node;
(3b) when the response time slot arrives, the large elliptic orbit satellite allocates the service time slot according to the time slot allocation algorithm, and the method comprises the following steps:
(3b1) firstly, inquiring an array, recording the number of nodes needing to be reserved in the nodes of the subnet 1, if the number of the nodes is not more than 10, sequentially dividing 10 dynamic time slots into each node according to the sequence of high priority, low priority and reserved node ID number from small to large, wherein each node has 1 time slot;
(3b2) if the number of nodes to be reserved in the subnet 1 is more than 10 and the number of the high-priority nodes is less than 10, the requirement of the high-priority nodes is met, and then the rest time slots are allocated to the low-priority nodes;
(3b3) if the number of the high priorities is more than 10, sequentially dividing 10 dynamic time slots into 10 high-priority nodes according to the descending order of the ID numbers of the nodes;
(3b4) and creating a time slot reservation response packet, sending the time slot reservation response packet to a sender corresponding to the subnet 1, and broadcasting the message to the nodes of the subnet 1.
(3b5) And repeating the steps (3b1) - (3b4), respectively dividing the time slots for other subnets, and respectively broadcasting the response packets to the nodes of other subnets.
4. The hybrid access method of satellite channels based on pre-allocation and on-demand reservation according to claim 1, wherein the air node performs service slot occupation according to the response message of the large elliptic orbit satellite to transmit the service packet, comprising the steps of:
(4a) after receiving the time slot reservation response packet, the air node checks whether the response packet has the own node ID number or not, and if the response packet does not indicate that the service time slot is not reserved successfully; if the service time slot reservation is successful, the corresponding service time slot number is continuously checked;
(4b) calculating the time of the node occupying the service time slot according to the service time slot number;
(4c) when the time of occupying the service time slot by the node is calculated in the step (4b), calculating the packet sending quantity of one time slot according to the length of the service time slot and the packet sending rate, then counting the quantity of the packets queued in the queue at the moment, and taking a smaller value as the quantity of the packets sent by occupying the service time slot at this time;
(4d) the packets queued in the queue are sequentially transmitted to the sender on a first-in-first-out basis.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113365339A (en) * | 2021-04-25 | 2021-09-07 | 北京遥测技术研究所 | Satellite access method based on reservation application time slot |
| CN114449668A (en) * | 2022-04-12 | 2022-05-06 | 希诺麦田技术（深圳）有限公司 | Time slot expansion method, system and equipment |
| CN116506950A (en) * | 2023-06-27 | 2023-07-28 | 南京控维通信科技有限公司 | Dynamic time slot allocation method based on QoS strategy |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090003306A1 (en) * | 2005-10-31 | 2009-01-01 | Israel Aerospace Industries, Ltd. | Dynamic time-slot allocation and QoS priority access in a mobile ad hoc network |
| US7940714B1 (en) * | 2003-11-26 | 2011-05-10 | Vt Idirect, Inc. | Method, apparatus, and system for transmitting control information in a communication network |
| CN102264116A (en) * | 2011-09-01 | 2011-11-30 | 哈尔滨工程大学 | Node network access method based on distributed time division multiple access wireless ad hoc network |
| CN103929818A (en) * | 2014-04-22 | 2014-07-16 | 北京航空航天大学 | Time slot allocation protocol of aircraft autonomous formation supporting network |
| CN104244257A (en) * | 2014-09-03 | 2014-12-24 | 北京航空航天大学 | Self-adaptation reservation and dynamic time slot distribution method and device |
| CN104601363A (en) * | 2014-12-03 | 2015-05-06 | 上海交通大学 | Orbit and domain partition type double-layer satellite network system and management method |
| CN105743562A (en) * | 2016-03-21 | 2016-07-06 | 南京邮电大学 | Satellite network access method based on predicted dynamic bandwidth allocation |
| CN108430111A (en) * | 2018-01-26 | 2018-08-21 | 西安电子科技大学 | Mixed type time slot reservation method in Distributed T DMA agreements |
| CN110166108A (en) * | 2019-04-30 | 2019-08-23 | 中国人民解放军军事科学院国防科技创新研究院 | Low orbit satellite time division multiple acess cut-in method |
-
2020
- 2020-10-15 CN CN202011101119.XA patent/CN112217728A/en active Pending
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7940714B1 (en) * | 2003-11-26 | 2011-05-10 | Vt Idirect, Inc. | Method, apparatus, and system for transmitting control information in a communication network |
| US20090003306A1 (en) * | 2005-10-31 | 2009-01-01 | Israel Aerospace Industries, Ltd. | Dynamic time-slot allocation and QoS priority access in a mobile ad hoc network |
| CN102264116A (en) * | 2011-09-01 | 2011-11-30 | 哈尔滨工程大学 | Node network access method based on distributed time division multiple access wireless ad hoc network |
| CN103929818A (en) * | 2014-04-22 | 2014-07-16 | 北京航空航天大学 | Time slot allocation protocol of aircraft autonomous formation supporting network |
| CN104244257A (en) * | 2014-09-03 | 2014-12-24 | 北京航空航天大学 | Self-adaptation reservation and dynamic time slot distribution method and device |
| CN104601363A (en) * | 2014-12-03 | 2015-05-06 | 上海交通大学 | Orbit and domain partition type double-layer satellite network system and management method |
| CN105743562A (en) * | 2016-03-21 | 2016-07-06 | 南京邮电大学 | Satellite network access method based on predicted dynamic bandwidth allocation |
| CN108430111A (en) * | 2018-01-26 | 2018-08-21 | 西安电子科技大学 | Mixed type time slot reservation method in Distributed T DMA agreements |
| CN110166108A (en) * | 2019-04-30 | 2019-08-23 | 中国人民解放军军事科学院国防科技创新研究院 | Low orbit satellite time division multiple acess cut-in method |
Non-Patent Citations (3)
| Title |
|---|
| A.M. LEWIS，等: ""Quality of service for tactical data links: TDMA with dynamic scheduling"", 《MILCOM 2005 - 2005 IEEE MILITARY COMMUNICATIONS CONFERENCE》 * |
| 王雪: ""基于业务状态的飞行器网络混合多址接入方案研究"", 《中国优秀硕士学位论文全文数据库信息科技辑》 * |
| 郑繁繁: ""一种动态时分复用接入协议设计"", 《科学技术创新》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113365339A (en) * | 2021-04-25 | 2021-09-07 | 北京遥测技术研究所 | Satellite access method based on reservation application time slot |
| CN114449668A (en) * | 2022-04-12 | 2022-05-06 | 希诺麦田技术（深圳）有限公司 | Time slot expansion method, system and equipment |
| CN116506950A (en) * | 2023-06-27 | 2023-07-28 | 南京控维通信科技有限公司 | Dynamic time slot allocation method based on QoS strategy |
| CN116506950B (en) * | 2023-06-27 | 2023-09-15 | 南京控维通信科技有限公司 | Dynamic time slot allocation method based on QoS strategy |
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