CN103634842A - Inter-group routing method for distributed satellite network - Google Patents

Abstract

The invention provides an inter-group routing method for a distributed satellite network. The inter-group routing method comprises the following steps: in the case that data in source satellite groups within the distributed satellite network needs to be sent, sending a routing request to main satellites of the respective satellite groups within the distributed satellite network; collecting the information of the satellite and pheromone values in an AODV (Ad Hoc on-demand distance vector) routing protocol once the routing request arrives at the main satellite of each satellite group; calculating the probability of sending the routing request to each satellite according to a next-hop selection algorithm, and selecting the next-hop satellite for sending the routing request from each satellite according to the calculated probability of each satellite; updating partial pheromones according to the time delay and available bandwidth of a link once a satellite is passed, and selecting the next-hop satellite for sending the routing request according to the partial pheromones; and generating a routing reply after the target satellite receives the routing request, thus establishing reverse routing between the source satellite and the target satellite. According to the inter-group routing method provided by the invention, a communication time delay is shortened, the available bandwidth of the link is increased, and the communication quality of the link is improved.

Description

Method for routing between a kind of distributed satellite network group

Technical field

The invention belongs to group of stars networking technology area, relate to method for routing between a kind of distributed satellite network group.

Background technology

At present, existing satellite routing algorithm is divided into virtual topology routing algorithm and dummy node routing algorithm two classes according to topology of networks.These satellite routing algorithms are mostly for low orbit satellite design, and constellation change in topology is very fast, and does not consider the state of link.And the topology of a distributed group of stars is relatively stable, so traditional Routing Protocol can not be directly applied for distributed group of stars network.

Summary of the invention

The present invention is directed to the proposition of above problem, and method for routing between the distributed satellite network group who proposes, solved the problem of distributed group of stars route.

On the one hand, the invention provides method for routing between a kind of distributed satellite network group, comprising:

When source satellite group exists data to send in distributed satellite network, route requests is sent to the primary place of the satellite group separately in distributed network;

During a satellite group primary of the every arrival of described route requests, the information of collecting described satellite, and pheromones value in AODV Routing Protocol;

According to down hop selection algorithm, calculate the probability that described route requests will send to each satellite, from each satellite, according to the probability of each satellite calculating, select to send the down hop satellite of route requests;

Every through a satellite, according to chain-circuit time delay and link available bandwidth, upgrade local message element, according to described local message element, select to send the down hop satellite that route please be asked;

When described object satellite or arrive object Satellite Road by intermediate, satellite receive after described route requests, produce routing reply, thereby set up the reverse route between source satellite and object satellite.

Further, this distributed satellite network method for routing, also comprises:

After the route of setting up between source satellite and object satellite, by hello message packet, realize route maintenance, in described hello message packet, add energy object, dynamically notify the residue situation of neighbor node energy, energy information more is accurately provided during for selection route.

Further, above-mentioned down hop selection algorithm is specially ant algorithm, is specially:

$P_{\mathrm{ij}}^k\left(t\right)=\left\{\begin{array}{cc}\frac{{\left[{\mathrm{\τ}}_{\mathrm{ij}}\left(t\right)\right]}^{\mathrm{\α}}\×{\left[{\mathrm{\η}}_{\mathrm{ij}}\left(t\right)\right]}^{\mathrm{\β}}}{\underset{Z\⋐{\mathrm{allowed}}_k}{\mathrm{\Σ}}{\left[{\mathrm{\τ}}_{\mathrm{iz}}\left(t\right)\right]}^{\mathrm{\α}}\×{\left[{\mathrm{\η}}_{\mathrm{iz}}\left(t\right)\right]}^{\mathrm{\β}}}& j\⊂⃒{\mathrm{tabu}}_k\\ 0& \mathrm{otherwise}\end{array}\right.$

Wherein, in formula

for the t probability that ant k selecting paths (i, j) is advanced constantly; α is the pheromones factor, the significance level of characterization information element; η _ij(t) be heuristic function, equal the inverse of node i and node j distance, characterize the weight in path (i, j), β is the heuristic information factor, characterizes the significance level of heuristic information; Tabu _k(k=1,2 ..., m) be the taboo list of ant k, recorded the node that ant k has passed by; Allowed _k={ c-tabu _knext step allows the node of selecting to be illustrated in t moment ant k.

Further, above-mentioned according to chain-circuit time delay and link available bandwidth, upgrade local message element, be specially:

According to link weight, upgrade formula, calculate local message element

wherein, link weight renewal formula is:

$\mathrm{\Δ}{\mathrm{\τ}}_{\mathrm{ij}}^k\left(t\right)=\left\{\begin{array}{cc}\frac{Q+w_{\mathrm{ij}}}{d_{\mathrm{ij}}}& w_{\mathrm{ij}}\≤w\\ \frac{Q-w_{\mathrm{ij}}}{d_{\mathrm{ij}}}& \mathrm{Else}\end{array}\right.$

Wherein, Q represents the enhancing coefficient of pheromones; W represents the threshold value of link weight, and its initial value is w ₀; d _ijbe illustrated in k the path (i, j) that ant walks in this circulation, w _ijrepresent that node i is to the weight of link (i, j) between neighbor node j, its expression formula is as follows:

$w_{\mathrm{ij}}=\frac{D{(i,j)}^{{\mathrm{\α}}_{\text{1}}}}{\text{B}{(i,j)}^{{\mathrm{\β}}_1}}$

Wherein, D (i, j) represents the time delay on link (i, j), and B (i, j) represents the available bandwidth on link (i, j), α ₁and β ₁the relative significant coefficient that represents respectively bandwidth and time delay.

Effect of the present invention and benefit be, can effectively avoid that Link State is congested and the problems such as wait time delay increase that cause improve router efficiency.

Accompanying drawing explanation

Accompanying drawing 1 is the flow chart of method for routing between a kind of distributed satellite network group provided by the invention;

Accompanying drawing 2 is the flow chart that improved ant group algorithm of the present invention and AODV protocol application arrive satellite network;

The equivalent topologies structure chart of the Samsung group communication that accompanying drawing 3 is taked for emulation of the present invention;

The time slot dividing figure that accompanying drawing 4 is taked for emulation of the present invention;

Accompanying drawing 5 is emulation of the present invention broadband bottleneck comparison diagram;

Accompanying drawing 6 is simulation end to end time delay comparison diagram of the present invention.

Embodiment

Below in conjunction with technical scheme and accompanying drawing, describe the specific embodiment of the present invention in detail.

For existing Satellite Network Routing Algorithms, using path as route evaluation criterion, cause the not necessarily feature in optimum path of nearest path, propose a kind of route selection algorithm rapidly and efficiently.The method is considered the state of link, as available bandwidth, propagation delay time and the error rate etc., and source is driven to Routing Protocol (Ad hoc on-demand distance vector routing, AODV) application wherein, guarantee to reduce the time delay of satellite network communication under the optimal situation of path, with this, reach the optimum object of communication.

As shown in Figure 1, a kind of distributed satellite network group of stars method for routing of the embodiment of the present invention, comprising:

Step 1: when distributed satellite network group Satellite exists data to send, route requests is sent to the primary of the satellite group separately in distributed network, set up route between group by primary.

Step 2: during a satellite group primary of the every arrival of described route requests, the information of collecting described satellite group primary, and pheromones value in AODV Routing Protocol.

Step 3: according to down hop selection algorithm, calculate the probability that described route requests will send to each satellite group primary, from each satellite group primary, according to the probability of each satellite group primary calculating, select to send the down hop satellite of route requests.

Concrete: can utilize ant algorithm, thereby select down hop selection algorithm, concrete process is as follows:

Set constant N, w ₀, Q, ρ, n, α, β, and for every ant, an empty taboo list tabu is set _k.

By following formula (1), provide ant k and in node i, selected to move to the probability of adjacent node j:

$P_{\mathrm{ij}}^k\left(t\right)=\left\{\begin{array}{cc}\frac{{\left[{\mathrm{\&tau;}}_{\mathrm{ij}}\left(t\right)\right]}^{\mathrm{\&alpha;}}\&times;{\left[{\mathrm{\&eta;}}_{\mathrm{ij}}\left(t\right)\right]}^{\mathrm{\&beta;}}}{\underset{Z\&Subset;{\mathrm{allowed}}_k}{\mathrm{\&Sigma;}}{\left[{\mathrm{\&tau;}}_{\mathrm{iz}}\left(t\right)\right]}^{\mathrm{\&alpha;}}\&times;{\left[{\mathrm{\&eta;}}_{\mathrm{iz}}\left(t\right)\right]}^{\mathrm{\&beta;}}}& j\&NotSubset;{\mathrm{<figure-callout\; id="0"\; label="tabu\; k"\; filenames="HDA0000442411130000042.png"\; state="\{\{state\}\}">tabu</figure-callout>}}_k\\ 0& \mathrm{otherwise}\end{array}\right.---\left(1\right)$

Wherein, in formula

for the t probability that ant k selecting paths (i, j) is advanced constantly; α is the pheromones factor, the significance level of characterization information element; η _ij(t) be heuristic function, equal the inverse of node i and node j distance, i.e. η _ij(t)=1/d _ij, the weight in sign path (i, j), for ant k, d _ijless, η _ijit is (t) larger,

also just larger; The β heuristic information factor, the significance level of sign heuristic information; Tabu _k(k=1,2 ..., m) be the taboo list of ant k, recorded the node that ant k has passed by; Allowed _k={ c-tabu _knext step allows the node of selecting to be illustrated in t moment ant k.

Step 4: every through a satellite group primary, according to chain-circuit time delay and link available bandwidth, upgrade local message element, when described route requests arrive object satellite or arrive object Satellite Road by intermediate, satellite till.

Concrete process is as follows: As time goes on, when all ants complete after an iteration, the pheromones that pass by path to ant is upgraded.First original pheromones of volatilizing, then increases ant through the pheromones in path, and the more new formula of pheromones is as follows:

τ _ij(t+Δt)=(1-ρ)τ _ij(t)+τ _ij(Δt) (2)

${\mathrm{\&tau;}}_{\mathrm{ij}}\left(\mathrm{\&Delta;t}\right)=\underset{k=1}{\overset{m}{\mathrm{\&Sigma;}}}{\mathrm{\&tau;}}_{\mathrm{ij}}^k\left(\mathrm{\&Delta;t}\right)---\left(3\right)$

Wherein: the volatility coefficient of pheromones on ρ (0≤ρ <1) delegated path, what (1-ρ) represented is the residual factor of pheromones, τ _ijthe size of the pheromones increment of (Δ t) representative on path (i, j), initial time τ _ij(Δ t)=0.

If only consider 2 kinds of weight types of bandwidth and time delay in the embodiment of the present invention, node i is to the weight w of link between neighbor node j _ijbe calculated as follows:

$w_{\mathrm{ij}}=\frac{D{(i,j)}^{{\mathrm{\&alpha;}}_{\text{1}}}}{\text{B}{(i,j)}^{{\mathrm{\&beta;}}_1}}---\left(4\right)$

Wherein D (i, j) represents the time delay on link (i, j), and B (i, j) represents the available bandwidth on link (i, j).α ₁and β ₁the relative importance that represents respectively bandwidth and time delay, can be according to the specific requirement of bandwidth and time delay is regulated.

Group's routing algorithm is to make routing decision according to the size of pheromones on path, so can, using the state of link as the factor that affects pheromones increment, increase or reduce pheromones increment according to the congestion situation of link.When algorithm starts, set an initial link weight threshold w ₀, when the link weight of process while being less than this threshold value, pheromones intensity Q just adds the weight of this link, otherwise just deducts this link weight.The pheromones that the link that weight is less like this increases is just larger, thereby the possibility of being chosen by follow-up ant is just larger.

pheromones according to link weight update rule, by formula (5), represented.

$\mathrm{\&Delta;}{\mathrm{\&tau;}}_{\mathrm{ij}}^k\left(t\right)=\left\{\begin{array}{cc}\frac{Q+w_{\mathrm{ij}}}{d_{\mathrm{ij}}}& w_{\mathrm{ij}}\&le;w\\ \frac{Q-w_{\mathrm{ij}}}{d_{\mathrm{ij}}}& \mathrm{Else}\end{array}\right.---\left(5\right)$

Wherein Q represents the enhancing coefficient of pheromones; w _ijthe weight that represents link (i, j); W represents the threshold value of link weight, and its initial value is w ₀; d _ijbe illustrated in k the path (i, j) that ant walks in this circulation.

Step 5: described object satellite or arrive object Satellite Road by intermediate, satellite receive after described route requests, produce routing reply, thereby set up the reverse route between source satellite and object satellite.

Step 6: after the route of setting up between initial satellite and object satellite, by hello message packet, realize route maintenance, in described hello message packet, add energy object, dynamically notify the residue situation of neighbor node energy, energy information more is accurately provided during for selection route.

As shown in Figure 2, the ant group algorithm of the embodiment of the present invention and AODV protocol application are to satellite network flow chart, and concrete process is as follows: when a node is received Front ant for the first time, it can create a record in its routing table.This record comprises destination node address, next hop address, the parameters such as pheromone concentration.Wherein, in the renewal process of pheromone concentration, link weight is heavily taken into account.Node can be selected according to the concentration of pheromones the next-hop node of this Front ant, the value of while lastest imformation element, and Front ant can join this address of node in the route information table of oneself.Front ant is afterwards determined the next-hop node of oneself according to ant above through the pheromones value staying later, after Front ant arrives destination node, by its entrained routing iinformation, give destination node, destination node compares this routing iinformation and existing routing iinformation, finds best route.Destination node will send a backward successful ant to source node, and backward successful ant will get back to destination node through the optimal path being found by Front ant, and upgrade the pheromones value of the route of passing through.Like this, by source node, to the route of destination node, just set up for one.The node if Front ant misses one's aim within the rational time, the intermediate node by its process sends successively backward failed ant and discharges successively link.Use backward failed ant to avoid the unreachable problem in path of using reverse path life span to cause.

The equivalent topologies structure chart of the Samsung group communication that accompanying drawing 3 is taked for emulation of the present invention, the artificial network in scheme is the common ground network that adopts wire link to connect.As ground cable network, it is changeless in normal condition lower network, between each routing node, whether being communicated with, and the topology of network is changeless, and this is mainly that planning due to the networking initial stage determines.In simulation process, by artificial intervention, control each routing node to the break-make of circuit, thereby reach the topological object of controlling and changing network.In NS2, set up simulation mobile-satellite net, the condition of network is as follows: three mutual traffic models of constellation that 1. in network using, rail is combined with low rail.2. low rail is 5 780 kilometers of high pole orbits, 5 satellites of every track.3. middle rail is two constellations, and each constellation is 4 10350 kilometers of high pole orbits, 2 satellites of every track.4. in low rail layer, every star only keeps inter-satellite link with four adjacent stars all around; In high rail layer, every star only keeps inter-satellite link with three adjacent satellites.5. the switching of inter-satellite link mainly occurs in interlayer, between low rail and middle rail star, and low rail star with the shortest principle of distance, select in rail star set up inter-satellite link.6. can choose according to the requirement of emulation the length of time slot.In this emulation, in order to improve simulation velocity, set each time slot long 5 minutes.

Fig. 4 is the time slot dividing figure that emulation of the present invention is taked, concrete grammar is: in emulation, be divided into the timeslice that several length are Δ t the whole system cycle, be divided into N time slot, the size of timeslice depends on the simulation accuracy that requirement reaches, the less scheme that timeslice is chosen is better to the emulation degree of truth, and the precision of final simulation result is just high.In simulation process, take the initial renewal network topology at each time slot.

During emulation, setting source node is a group of stars 1, and destination node is a group of stars 2, iterations N=60, pheromones intensity Q=10, volatility coefficient ρ=0.5, heuristic factor-alpha=1, β=5, ant number n=20.Pheromone concentration during beginning on every link is identical, ant is selecting paths randomly, after a node of each selection, to link between two of process nodes according to the time delay in path, bandwidth situation is carried out pheromones renewal, after this ant selecting paths can be subject to the impact of former generation ant, and process n is for alternating and then finding optimal path.

Finally the satellite network of setting up has been carried out to simple performance simulation and assessment, accompanying drawing 5 emulation of the present invention broadband bottleneck comparison diagram, and accompanying drawing 6 is simulation end to end time delay comparison diagram of the present invention.

By distributed satellite network method for routing of the present invention, by by AODV protocol application in the improved ant group algorithm based on link weight, the realistic demand of this routing algorithm, there is very strong communication Route Selection meaning, and overcome the shortcoming of traditional ignorance link weight, reduce satellite network Route establishment time delay, improved satellite network communication efficiency.

The above; this is preferably embodiment of the present invention; but protection scope of the present invention is not limited to this; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses; according to technical scheme of the present invention and inventive concept thereof, be equal to replacement or changed, within all should being encompassed in protection scope of the present invention.

Claims (4)

1. a method for routing between distributed satellite network group, is characterized in that, comprising:

When source satellite group exists data to send in distributed satellite network, route requests is sent to the primary place of the satellite group separately in distributed network;

During a satellite group primary of the every arrival of described route requests, the information of collecting described satellite, and pheromones value in AODV Routing Protocol;

According to down hop selection algorithm, calculate the probability that described route requests will send to each satellite, from each satellite, according to the probability of each satellite calculating, select to send the down hop satellite of route requests;

Every through a satellite, according to chain-circuit time delay and link available bandwidth, upgrade local message element, according to described local message element, select to send the down hop satellite that route please be asked;

When described object satellite or arrive object Satellite Road by intermediate, satellite receive after described route requests, produce routing reply, thereby set up the reverse route between source satellite and object satellite.

2. method for routing between a kind of distributed satellite network group as claimed in claim 1, is characterized in that, also comprises:

After the route of setting up between source satellite and object satellite, by hello message packet, realize route maintenance.

3. method for routing between a kind of distributed satellite network group as claimed in claim 1, is characterized in that, described down hop selection algorithm is specially ant algorithm, is specially:

$P_{\mathrm{ij}}^k\left(t\right)=\left\{\begin{array}{cc}\frac{{\left[{\mathrm{\&tau;}}_{\mathrm{ij}}\left(t\right)\right]}^{\mathrm{\&alpha;}}\&times;{\left[{\mathrm{\&eta;}}_{\mathrm{ij}}\left(t\right)\right]}^{\mathrm{\&beta;}}}{\underset{Z\&Subset;{\mathrm{allowed}}_k}{\mathrm{\&Sigma;}}{\left[{\mathrm{\&tau;}}_{\mathrm{iz}}\left(t\right)\right]}^{\mathrm{\&alpha;}}\&times;{\left[{\mathrm{\&eta;}}_{\mathrm{iz}}\left(t\right)\right]}^{\mathrm{\&beta;}}}& j\&NotSubset;{\mathrm{tabu}}_k\\ 0& \mathrm{otherwise}\end{array}\right.$

Wherein, in formula

for the t probability that ant k selecting paths (i, j) is advanced constantly; α is the pheromones factor, the significance level of characterization information element; η _ij(t) be heuristic function, equal the inverse of node i and node j distance, characterize the weight in path (i, j), β is the heuristic information factor, characterizes the significance level of heuristic information; Tabu _k(k=1,2 ..., m) be the taboo list of ant k, recorded the node that ant k has passed by; Allowed _k={ c-tabu _knext step allows the node of selecting to be illustrated in t moment ant k.

4. method for routing between a kind of distributed satellite network group as claimed in claim 1, is characterized in that, described according to chain-circuit time delay and link available bandwidth, upgrades local message element, is specially:

According to link weight, upgrade formula, calculate local message element

wherein, link weight renewal formula is:

$\mathrm{\&Delta;}{\mathrm{\&tau;}}_{\mathrm{ij}}^k\left(t\right)=\left\{\begin{array}{cc}\frac{Q+w_{\mathrm{ij}}}{d_{\mathrm{ij}}}& w_{\mathrm{ij}}\&le;w\\ \frac{Q-w_{\mathrm{ij}}}{d_{\mathrm{ij}}}& \mathrm{Else}\end{array}\right.$

Wherein, Q represents the enhancing coefficient of pheromones; W represents the threshold value of link weight, and its initial value is w ₀; d _ijbe illustrated in k the path (i, j) that ant walks in this circulation, w _ijrepresent that node i is to the weight of link (i, j) between neighbor node j, its expression formula is as follows:

$w_{\mathrm{ij}}=\frac{D{(i,j)}^{{\mathrm{\&alpha;}}_{\text{1}}}}{\text{B}{(i,j)}^{{\mathrm{\&beta;}}_1}}$

Wherein, D (i, j) represents the time delay on link (i, j), and B (i, j) represents the available bandwidth on link (i, j), α ₁and β ₁the relative significant coefficient that represents respectively bandwidth and time delay.

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