CN105979557A - Node satellite communication method based on sequential decision route handover - Google Patents

Abstract

The invention provides a node satellite communication method based on sequential decision route handover. The method is characterized in that optimal satellite handover is carried out on a low-earth-orbit satellite constellation through sequential decision route handover by making use of the signal strength of service provided by the node satellites of the low-earth-orbit satellite constellation for mobile terminals and the orientation of spot-beam service in order to reflect the continuity and uncertainty of route handover between the node satellites of the low-earth-orbit satellite constellation. All state variables, decision variables and adopted policies of mobile terminals at the node satellites in a time period t constitute a state variable set, a decision variable set and a policy set respectively, a sequential decision is made based on the data sets to get a feasible route handover policy set, and finally, an optimal route handover policy is decided based on a route handover objective function F. The method considers the route handover state in the mobile terminal service process of the node satellites. Secure and stable communication of a space network system is realized through the node satellite communication method based on sequential decision route handover.

Description

A kind of node satellite communication method based on sequential decision route handoff

Technical field

The present invention relates to a kind of node satellite communication method based on sequential decision route handoff, particularly relate at satellite high-speed motion And operational coverage area is when dynamically changing, use the node satellite conversion communication of sequential decision, it is achieved telex network Seriality and safety.

Background technology

Satellite communication system is to realize the important component part in global communication, and its medium and low earth orbit satellites (LEO) communication system covers with it The features such as area is wide, propagation delay time is little, low in energy consumption and high survivability, have important effect in modern communications field.

Low orbit satellite (LEO) system refers generally to run the satellite constellation that orbit altitude is about 500～1500km.Its single satellite is over the ground Area coverage little, with the speed more than 25000km/h relative to ground high-speed mobile, and the network topology of LEO constellation is at any time Between be continually changing.Therefore, LEO satellite constellation is often by tens of, and the most up to a hundred satellites form.But due to low orbit satellite system Unite relative to synchronizing stationary orbit, for the highest rail satellite (GEO), it is provided that shorter propagation delay time, and less path Loss.

In LEO mobile satellite communication system, due to satellite relative to ground translational speed quickly, this results in single satellite and is User provides time of service the shortest, is the time of about ten minutes.Thus, during telex network, can constantly defend Inter-satellite handover.According to the protocol hierarchy of switching, satellite network switching can be divided into link switching and network layer handoff.Link layer is cut Change and can be divided into spot beam switching, satellite switching and inter-satellite link switching.Satellite switching refers to owing to satellite is relative to the height on ground Speed is run, and mobile terminal changes to satellite B overlay area from satellite A overlay area.Wherein stars many for Constellation of Low Earth Orbit Satellites cover The situation of lid, according to which kind of criterion selectes and accesses the major issue that satellite is node satellite route handoff.Node satellite route handoff The quality of strategy directly influences the systematic functions such as call blocking rate, handover overhead and system channel utilization rate.Consider joint Point satellite state of route handoff in for mobile terminal service process, makes the most efficient satellite Routing Handover Strategy the heaviest Want.

Summary of the invention

The quality of node satellite Routing Handover Strategy directly influences call blocking rate, handover overhead and system channel utilization rate etc. Systematic function.Consider node satellite state of route handoff in for mobile terminal service process, make and rationally defending efficiently Star Routing Handover Strategy is extremely important.

For reaching above-mentioned purpose, the present invention provides a kind of node satellite methods based on sequential decision route handoff, the skill used Art scheme is:

As a kind of node satellite communication method based on sequential decision route handoff, it is characterised in that:

With seriality and the uncertainty of reflection Constellation of Low Earth Orbit Satellites node inter-satellite route handoff, Constellation of Low Earth Orbit Satellites is utilized to save Service signal power and spot beam that point satellite provides for mobile terminal service orientation, use sequential decision route handoff to defend low rail Star seat carries out optimization satellite switching.

As a kind of node satellite communication method based on sequential decision route handoff, the seriality of route handoff between low orbit satellite star Reflect with uncertainty:

The signal intensity of mobile terminal institute recipient node satellite service, the load of node satellite and covering are defended by low rail service time The impact of the translational speed of star, has successional change, additionally, Constellation of Low Earth Orbit Satellites is made up of numerous node satellites, accepts The position of the mobile terminal of service also changes constantly so that in node Satellite Road is by handoff procedure, next step may switch Node satellite is the most uncertain.

As a kind of node satellite communication method based on sequential decision route handoff, its low orbit satellite (LEO) constellation node satellite base Route handoff in sequential decision can be described as:

Currently provide service node satellitosis variable for mobile terminal, X (t) is t period able state collection；

Currently provide service node satellite decision variable for mobile terminal, U (t) is t period feasible decision variable collection；

Currently provide a strategy of service node satellite t period for mobile terminal, Z (t) is t period possible strategy collection；

D (κ) is a possible strategy collection of sequential decision problem, and wherein X, U, Z are followed successively by mobile terminal and currently provide service joint The point state space of satellite, decision space and policy space；

For feasible constraint collection；

Definition f be node Satellite Road by switching state transfer function, F is node satellite route handoff object function, it is assumed that ensure joint The shortest time of some satellite route handoff, reliability is the highest and the cycle of node satellite route handoff continuously and random, sequential certainly The optimization of plan route handoff is described as:

Sequential decision route handoff state transition equation:

Pass throughQuickly can go out lower a period of time according to the state variable of present node satellite, decision variable and the policy calculation taked The state of section, and the state of route handoff posterior nodal point satellite and former state onrelevant, so far, provide for mobile terminal The node satellite of service proceeds by the decision-making of route handoff next time.

The present invention has a following Advantageous Effects:

Than other Constellation of Low Earth Orbit Satellites node satellite switchover policy, the method considers node satellite for mobile terminal service During the state of route handoff, by a kind of method of node satellite communication strategy based on sequential decision route handoff, it is achieved A set of tight to spatial network security of system, stable communication means.

Accompanying drawing explanation

For the technical scheme in the clearer explanation embodiment of the present invention, below in conjunction with the accompanying drawings with specific embodiments to the present invention It is described further:

Fig. 1 is that LEO satellite constellation satellite switches schematic diagram.

Fig. 2 is the flow chart of node satellite communication method based on sequential decision route handoff.

Detailed description of the invention

The present invention is described in further detail below in conjunction with the accompanying drawings.

Satellite switching problem in Constellation of Low Earth Orbit Satellites network can be briefly described owing to high-speed mobile and the user of low orbit satellite move The movement of dynamic terminal, moves to the region that satellite B covers from the overlay area of satellite A.In this handoff procedure, mobile terminal By analyzing the pilot strength data that the follow-up all node satellites in the range of switching that will switch are sent, as from satellite A Overlay area move to satellite B cover region process in also have a satellite C overlay area, now need optimal joint Point satellite carries out channel switching, and after finishing switching, the interactive instruction of protosatellite is switched on follow-up node satellite, continues The service that mobile terminal is carried out.

As a kind of node satellite communication method based on sequential decision route handoff, it is characterised in that:

With seriality and the uncertainty of reflection Constellation of Low Earth Orbit Satellites node inter-satellite route handoff, Constellation of Low Earth Orbit Satellites is utilized to save Service signal power and spot beam that point satellite provides for mobile terminal service orientation, use sequential decision route handoff to defend low rail Star seat carries out optimization satellite switching.

As a kind of node satellite communication method based on sequential decision route handoff, the seriality of route handoff between low orbit satellite star Reflect with uncertainty:

The signal intensity of mobile terminal institute recipient node satellite service, the load of node satellite and covering are defended by low rail service time The impact of the translational speed of star, has successional change, additionally, Constellation of Low Earth Orbit Satellites is made up of numerous node satellites, accepts The position of the mobile terminal of service also changes constantly so that in node Satellite Road is by handoff procedure, next step may switch Node satellite is the most uncertain.

Between this low orbit satellite star, the process of sequential decision route handoff is in all states of node satellite by the mobile terminal t period Composition state variable collection, decision variable collection and the set of strategies of variable, decision variable and strategy used, according to these data sets Sequential decision obtains feasible Routing Handover Strategy collection, is finally made route handoff optimal switching strategy by route handoff object function F.

As a kind of node satellite communication method based on sequential decision route handoff, its low orbit satellite (LEO) constellation node satellite base Route handoff in sequential decision can be described as:

$X\left(t\right)=\{x_t^0,x_t^1,...,x_t^l\}$

Currently provide service node satellitosis variable for mobile terminal, X (t) is t period able state collection；

$U\left(t\right)=\{u_t^0,u_t^1,...,u_t^m\}$

Currently provide service node satellite decision variable for mobile terminal, U (t) is t period feasible decision variable collection；

$Z\left(t\right)=\{z_t^0,z_t^1,...,z_t^n\}$

Currently provide a strategy of service node satellite t period for mobile terminal, Z (t) is t period possible strategy collection；

$D\left(\mathrm{\κ}\right)=\{d_1^k,d_2^k,...,d_N^k\}$

D (κ) is a possible strategy collection of sequential decision problem, and wherein X, U, Z are followed successively by mobile terminal and currently provide service joint The point state space of satellite, decision space and policy space；

$\hat{u}=\{{\hat{u}}_1,{\hat{u}}_2,\mathrm{...},{\hat{u}}_v\}$

For feasible constraint collection；

Definition f be node Satellite Road by switching state transfer function, F is node satellite route handoff object function, it is assumed that ensure joint The shortest time of some satellite route handoff, reliability is the highest and the cycle of node satellite route handoff continuously and random, sequential certainly The optimization of plan route handoff is described as:

$optF\left(t\right)=F(t,x_t^l,u_t^m,z_t^n)(t=1,2,...,N)$

Sequential decision route handoff state transition equation:

$x_{t+1}^n=f(t,x_t^l,u_t^m,z_t^n)$

Pass throughQuickly can go out lower a period of time according to the state variable of present node satellite, decision variable and the policy calculation taked The state of section, and the state of route handoff posterior nodal point satellite and former state onrelevant, so far, provide for mobile terminal The node satellite of service proceeds by the decision-making of route handoff next time.

The LEO satellite communication systems being made up of multi-satellite has that area coverage is wide, propagation delay time is little, low in energy consumption and high anti-ruin The features such as property, play an important role in modern communications field.Nowadays, low orbit satellite as the backbone node of communication system, Its high-speed mobile over the ground, causes satellite network topological structure Rapid Variable Design, and frequently, this allows for communicating in satellite-ground link switching In journey, the probability of data packet disorder is greatly increased, and the safety of the process of communication is also produced by the opening of space communication system Give birth to the biggest impact.The present invention relates to a kind of node satellite communication method based on sequential decision route handoff, particularly relate to When satellite high-speed motion and operational coverage area dynamically change, use the node satellite conversion communication of sequential decision, protect Demonstrate,prove the stability of communication process, and malicious attack has been had certain Initiative Defense, it is achieved the stability of telex network, company Continuous property and safety.

Claims (3)

1. a node satellite communication method based on sequential decision route handoff, it is characterised in that:

With seriality and the uncertainty of reflection Constellation of Low Earth Orbit Satellites node inter-satellite route handoff, Constellation of Low Earth Orbit Satellites is utilized to save Service signal power and spot beam that point satellite provides for mobile terminal service orientation, use sequential decision route handoff to defend low rail Star seat carries out optimization satellite switching.

A kind of node satellite communication method based on sequential decision route handoff the most according to claim 1, it is characterised in that:

The seriality of route handoff and uncertain reflection between low orbit satellite star:

The signal intensity of mobile terminal institute recipient node satellite service, the load of node satellite and covering are defended by low rail service time The impact of the translational speed of star, has successional change, additionally, Constellation of Low Earth Orbit Satellites is made up of numerous node satellites, accepts The position of the mobile terminal of service also changes constantly so that in node Satellite Road is by handoff procedure, next step may switch Node satellite is the most uncertain.

A kind of node satellite communication method based on sequential decision route handoff the most according to claim 1, it is characterised in that:

Low orbit satellite (LEO) constellation node satellite route handoff based on sequential decision can be described as:

Currently provide service node satellitosis variable for mobile terminal, X (t) is t period able state collection；

Currently provide service node satellite decision variable for mobile terminal, U (t) is t period feasible decision variable collection；

Currently provide a strategy of service node satellite t period for mobile terminal, Z (t) is t period possible strategy collection；

D (κ) is a possible strategy collection of sequential decision problem, and wherein X, U, Z are followed successively by mobile terminal and currently provide service joint The point state space of satellite, decision space and policy space；

For feasible constraint collection；

Definition f be node Satellite Road by switching state transfer function, F is node satellite route handoff object function, it is assumed that ensure joint The shortest time of some satellite route handoff, reliability is the highest and the cycle of node satellite route handoff continuously and random, sequential certainly The optimization of plan route handoff is described as:

Sequential decision route handoff state transition equation:

Pass throughQuickly can go out lower a period of time according to the state variable of present node satellite, decision variable and the policy calculation taked The state of section, and the state of route handoff posterior nodal point satellite and former state onrelevant, so far, provide for mobile terminal The node satellite of service proceeds by the decision-making of route handoff next time.