CN110366205B - Method and device for selecting initial source node in mobile opportunity network traffic unloading - Google Patents
Method and device for selecting initial source node in mobile opportunity network traffic unloading Download PDFInfo
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Abstract
The embodiment of the invention provides a method, a device and electronic equipment for selecting an initial source node in mobile opportunity network flow unloading, wherein a link change relation between nodes in a preset time period in a mobile opportunity network is obtained, and a weighted reachable graph is generated according to the link change relation; based on the weighted reachable graph, dynamically allocating the resource values of the nodes according to a preset resource value allocation strategy; and when the resource value of each node reaches a stable state, selecting an initial source node according to the size relationship of the resource value of each node. By applying the embodiment of the invention, in the process of selecting the initial source node, the link change relation of the mobile opportunity network is considered, and even if the topological structure of the mobile opportunity network changes greatly, the node with strong transmission capability in the mobile opportunity network can be more effectively identified as the initial source node, so that the data transmission efficiency is improved.
Description
Technical Field
The present invention relates to the field of mobile communications, and in particular, to a method and an apparatus for selecting an initial source node in mobile opportunistic network traffic offloading, and an electronic device.
Background
Users usually use mobile networks to acquire various network resources, such as news information, music resources or video resources, so that the traffic pressure of the mobile networks is increasing. Currently, in some traffic offload schemes, part of data of the mobile network may be offloaded to other networks, such as opportunistic networks, WIFI (Wireless-Fidelity, Wireless broadband), and the like, for transmission, so as to reduce traffic pressure of the mobile network.
In a flow unloading scenario, for example: when the opportunistic network is used for transmission, that is, when traffic is unloaded in the mobile opportunistic network, some nodes with higher liveness are generally selected as initial source nodes, and when data resources are transmitted, the content server firstly transmits data to the initial source nodes, and then the initial source nodes further transmit the data to other nodes in the mobile opportunistic network. In the existing scheme, data transmission capability of each node in a network is generally measured by using an importance metric (e.g., degree-centrality, betweenness-centrality, etc.), and a node with a high index value (e.g., degree-centrality index value) of the importance metric is determined as an initial source node.
The importance metric is mainly used for measuring the data transmission capacity of the nodes in the network with a stable topological structure, but for the mobile opportunistic network with a large topological structure change, if the importance metric is directly applied, the data transmission capacity of the nodes cannot be accurately described, so that an initial source node with strong data transmission capacity cannot be effectively determined, and the efficiency of data transmission in the mobile opportunistic network is low.
Disclosure of Invention
The embodiment of the invention aims to provide a method, a device and electronic equipment for selecting an initial source node in mobile opportunity network flow unloading, so as to improve the efficiency of data transmission. The specific technical scheme is as follows:
in a first aspect, an embodiment of the present invention provides a method for selecting an initial source node in mobile opportunistic network traffic offloading, where the method includes:
acquiring a link change relation between nodes in a mobile opportunity network within a preset time period, wherein the mobile opportunity network comprises a preset number of nodes within the preset time period;
generating a weighted reachable graph according to the link change relationship; the weighted reachability graph is a directed network graph formed by nodes and edges, the nodes in the weighted reachability graph represent the nodes contained in the mobile opportunity network, and the edges in the weighted reachability graph represent the link change relationship among the nodes;
based on the weighted reachable graph, dynamically allocating the resource values of the nodes according to a preset resource value allocation strategy;
and when the resource value of each node reaches a stable state, selecting an initial source node according to the size relationship of the resource value of each node.
Further, the step of generating a weighted reachability graph according to the link change relationship includes:
for each node, determining a time sequence path between the node and other nodes in the mobile opportunity network in the preset time period according to the link change relation;
for each node, determining an instantaneous path between the node and other nodes in the mobile opportunity network according to the link change relationship;
a weighted reachability graph is generated based on the determined timing path and transient path.
Further, the step of determining, for each node, a timing path between the node and another node in the mobile opportunistic network within the preset time period according to the link change relationship includes:
acquiring the distance change relation between each node in the preset time period according to the link change relation;
and for each node, determining a time sequence path existing between the node and other nodes in the mobile opportunity network in the preset time period according to the distance change relation.
Further, the step of determining, for each node, an instantaneous path between the node and other nodes in the mobile opportunistic network according to the link change relationship includes:
acquiring the distance between each node at the communication moment in the preset time period according to the link change relation; the communication time is the time point of establishing communication between the nodes;
and determining the instant path existing between the node and other nodes in the mobile opportunity network at the communication moment according to the distance for each node.
Further, a unidirectional edge between nodes in the weighted reachability graph represents a temporal path, and a bidirectional edge between nodes in the weighted reachability graph represents a temporal path;
the step of dynamically allocating the resource values of the nodes according to a preset resource value allocation strategy based on the weighted reachable graph comprises the following steps:
adding background nodes in the weighted reachable graph, and establishing transient paths between the background nodes and each node in the weighted reachable graph;
setting the initial resource value of the background node to be 0, and setting the initial resource value of each node except the background node in the weighted reachable graph to be a unit resource value;
and dynamically allocating the resource value of each node according to the following formula:
wherein, the node viIs a node vjA neighbor node of vj(t) denotes the node v at time tjResource value of vi(t +1) represents the node v at time t +1iResource value of, wjiRepresenting a slave node vjTo node viWeight on directed edges, wjiIs equal to the node v within the preset time periodjAnd node viSum of the number of time-series paths and transient paths existing in between, sumw (j) represents the node vjThe sum of the weights of all the outgoing edges, wherein N represents the number of nodes for generating the weighted reachable graph in the mobile opportunity network;
when the resource value of each node reaches a stable state, the step of selecting an initial source node according to the magnitude relation of the resource values of each node comprises the following steps:
when the resource value of each node reaches a stable state, the resource value of the background node is averagely distributed to each node except the background node in the weighted reachable graph, and the final resource value of each node except the background node in the weighted reachable graph is obtained;
and selecting an initial source node according to the magnitude relation of the final resource values of all nodes except the background node in the weighted reachable graph.
In a second aspect, an embodiment of the present invention provides an apparatus for selecting an initial source node in mobile opportunistic network traffic offloading, where the apparatus includes:
the mobile opportunity network comprises an acquisition module, a processing module and a processing module, wherein the acquisition module is used for acquiring a link change relation between nodes in a preset time period in the mobile opportunity network, and the mobile opportunity network comprises a preset number of nodes in the preset time period;
the weighted reachability graph generation module is used for generating a weighted reachability graph according to the link change relation; the weighted reachability graph is a directed network graph formed by nodes and edges, the nodes in the weighted reachability graph represent the nodes contained in the mobile opportunity network, and the edges in the weighted reachability graph represent the link change relationship among the nodes;
the resource value allocation module is used for dynamically allocating the resource values of the nodes according to a preset resource value allocation strategy based on the weighted reachable graph;
and the initial source node selection module is used for selecting the initial source node according to the size relationship of the resource values of the nodes when the resource values of the nodes reach a stable state.
Further, the weighted reachability graph generation module includes: a time sequence path determining submodule, an instantaneous path determining submodule and a weighted reachability graph generating submodule;
the time sequence path determining submodule is used for determining a time sequence path between each node and other nodes in the mobile opportunity network in the preset time period according to the link change relation;
the instantaneous path determining submodule is used for determining an instantaneous path between each node and other nodes in the mobile opportunity network according to the link change relation;
and the weighted reachability graph generation submodule is used for generating a weighted reachability graph according to the determined time sequence path and the determined instantaneous path.
Further, the time sequence path determining submodule is specifically configured to obtain a distance change relationship between nodes in the preset time period according to the link change relationship; and for each node, determining a time sequence path existing between the node and other nodes in the mobile opportunity network in the preset time period according to the distance change relation.
Further, a unidirectional edge between nodes in the weighted reachability graph represents a temporal path, and a bidirectional edge between nodes in the weighted reachability graph represents a temporal path;
the resource value allocation module includes: a background node adding submodule, an initial resource value setting submodule and a resource value dynamic allocation submodule;
the background node adding submodule is used for adding background nodes in the weighted reachable graph and establishing instantaneous paths between the background nodes and each node in the weighted reachable graph;
the initial resource value setting submodule is configured to set the initial resource value of the background node to 0, and set the initial resource value of each node except the background node in the weighted reachability graph to a unit resource value;
the resource value dynamic allocation submodule is configured to dynamically allocate the resource value of each node according to the following formula:
wherein, the node viIs a node vjA neighbor node of vj(t) denotes the node v at time tjResource value of vi(t +1) represents the node v at time t +1iResource value of, wjiRepresenting a slave node vjTo node viWeight on directed edges, wjiIs equal to the node v within the preset time periodjAnd node viSum of the number of time-series paths and transient paths existing in between, sumw (j) represents the node vjThe sum of the weights of all the outgoing edges, wherein N represents the number of nodes for generating the weighted reachable graph in the mobile opportunity network;
the initial source node selection module is specifically configured to: when the resource value of each node reaches a stable state, the resource value of the background node is averagely distributed to each node except the background node in the weighted reachable graph, and the final resource value of each node except the background node in the weighted reachable graph is obtained; and selecting an initial source node according to the magnitude relation of the final resource values of all nodes except the background node in the weighted reachable graph.
In a third aspect, an embodiment of the present invention provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, where the processor and the communication interface complete communication between the memory and the processor through the communication bus;
a memory for storing a computer program;
and the processor is used for realizing the steps of the selection method of the initial source node in any mobile opportunity network flow unloading when the program stored on the memory is executed.
In a fourth aspect, embodiments of the present invention further provide a computer-readable storage medium, where a computer program is stored, and when the computer program runs on a computer, the computer is caused to execute any one of the methods for selecting an initial source node in mobile opportunistic network traffic offloading described above.
The embodiment of the invention provides a method, a device and electronic equipment for selecting an initial source node in mobile opportunity network flow unloading, which are used for obtaining a link change relation between nodes in a preset time period in a mobile opportunity network, wherein the mobile opportunity network comprises a preset number of nodes in the preset time period; generating a weighted reachable graph according to the link change relationship; the weighted reachability graph is a directed network graph formed by nodes and edges, the nodes in the weighted reachability graph represent the nodes contained in the mobile opportunity network, and the edges in the weighted reachability graph represent the link change relationship among the nodes; based on the weighted reachable graph, dynamically allocating the resource values of the nodes according to a preset resource value allocation strategy; and when the resource value of each node reaches a stable state, selecting an initial source node according to the size relationship of the resource value of each node. In the embodiment of the invention, in the process of selecting the initial source node, the link change relation of the mobile opportunity network is considered, and even if the topological structure of the mobile opportunity network changes greatly, the resource value can be distributed based on the weighted reachable graph generated by the link change relation of the mobile opportunity network, so that the initial source node with strong data transmission capability is selected according to the stabilized resource value of each node, and the data transmission efficiency is improved.
Of course, not all of the advantages described above need to be achieved at the same time in the practice of any one product or method of the invention.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart illustrating a method for selecting an initial source node in mobile opportunistic network traffic offloading according to an embodiment of the present invention;
fig. 2 is another flowchart illustrating a method for selecting an initial source node in mobile opportunistic network traffic offloading according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a generated weighted reachable graph according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of an initial source node selection apparatus according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to improve the efficiency of data transmission in a mobile network, embodiments of the present invention provide a method, an apparatus, and an electronic device for selecting an initial source node in mobile opportunistic network traffic offloading.
As shown in fig. 1, fig. 1 is a flowchart illustrating a method for selecting an initial source node in mobile opportunistic network traffic offloading according to an embodiment of the present invention, where the method may include:
step 101: acquiring a link change relation between nodes in a mobile opportunity network within a preset time period, wherein the mobile opportunity network comprises a preset number of nodes within the preset time period.
For example, the mobile opportunistic network may be a communication network formed by mobile terminals; alternatively, the mobile opportunity network may be a vehicle-mounted network, that is, a communication network formed by vehicle-mounted devices; the particular form of the mobile opportunistic network is not limited.
For example, before step 101, the mobile opportunistic network may be modeled, which may be used
It is shown that, among others,
representing the set of all nodes in the mobile opportunistic network,
wherein v is1,v2,…,vnRepresenting nodes, representing a set of links existing between nodes,
wherein e is1,e2,…emAnd representing links between nodes, wherein n is the number of nodes in the mobile opportunity network, and m is the number of links existing between the nodes in the mobile opportunity network.
When the distance between two nodes is less than the preset wirelessWhen the distance R is communicated, the two nodes can communicate with each other, and the link relationship between the two nodes is changed from the link relationship not existing to the link relationship existing. For any link e ∈ is represented by a quadruple (u, v, t, λ), where
Representing the two nodes that establish the link, t is the meeting time of u and v, λ is the duration of the link, and t + λ is the end time of the link. The start time and duration of edge e are denoted by t (e) and λ (e), respectively.
And 102, generating a weighted reachable graph according to the link change relationship.
The weighted reachability graph is a directed network graph formed by nodes and edges, the nodes in the weighted reachability graph represent the nodes included in the mobile opportunity network, and the edges in the weighted reachability graph represent the link change relationship among the nodes.
Further, for each node, according to the link change relationship, a timing path between the node and another node in the mobile opportunity network and an instantaneous path between the node and another node in the mobile opportunity network within the preset time period are determined, and then, according to the determined timing path and instantaneous path, a weighted reachable graph is generated, where the timing path is a communication path established between the nodes within the preset time period, and the instantaneous path is a communication path established between the nodes at each communication time within the preset time period, where the communication time may be a time point at which communication is established between the nodes.
In particular, a timing path
Is a sequential set of a series of nodes
For any 1. ltoreq. i. ltoreq.k,
representing a timing path
The ith ordered edge of (c), and (t) is to be satisfiedi+λi)≤ti+1. By using
And
respectively representing time-sequential paths
At the start time t1And an end time tk+λk. The timing path actually represents a path of opportunistic communication from a source node to a destination node. Timing path
Is defined as
It represents the delay in opportunistic communication from the source node to the destination node; time t slave node viTo node vjMay also be represented as a sequential set of a series of nodes
Where a path between any two nodes is established at time t.
Further, for each node, according to the link change relationship, a specific implementation manner of determining a timing path between the node and another node in the mobile opportunistic network within the preset time period may be:
acquiring a distance change relation between nodes in a preset time period according to the link change relation; and for each node, determining a time sequence path existing between the node and other nodes in the mobile opportunity network in the preset time period according to the distance change relation between the nodes.
Further, for each node, according to the link change relationship, a specific implementation manner of determining an instantaneous path between the node and other nodes in the mobile opportunity network may be:
acquiring the distance between each node at the communication moment in the preset time period according to the link change relation; the communication time is the time point of establishing communication between the nodes;
and determining the instant path existing between the node and other nodes in the mobile opportunity network at the communication moment according to the distance for each node.
And 103, dynamically allocating the resource values of the nodes according to a preset resource value allocation strategy based on the weighted reachable graph.
Further, the step of dynamically allocating resource values of each node may be:
adding background nodes in the weighted reachable graph, and establishing transient paths between the background nodes and each node in the weighted reachable graph;
setting the initial resource value of the background node to be 0, and setting the initial resource value of each node except the background node in the weighted reachable graph to be a unit resource value;
and dynamically allocating the resource value of each node according to the following formula:
wherein, the node viIs a node vjA neighbor node of vj(t) denotes the node v at time tjResource value of vi(t +1) represents the node v at time t +1iResource value of, wjiRepresenting a slave node vjTo node viWeight on directed edges, wjiIs equal to the node v within the preset time periodjAnd node viSum of the number of time-series paths and transient paths existing in between, sumw (j) represents the node vjThe sum of the weights of all outgoing edges, N denotesThe number of nodes generating a weighted reachability graph in the mobile opportunity network;
for example, after a weighted reachable graph including E links at N nodes is generated, a background node (group node) is added in the weighted reachable graph, and unidirectional links from the background node to the N nodes and unidirectional links from the N nodes to the background node are respectively added between the background node and the N nodes in the weighted reachable graph, thereby obtaining a strong connectivity graph including N +1 nodes and E +2N links, where a link exists between any two nodes in the strong connectivity graph. In an initial state, defining the resource value of a background node to be 0, wherein the resource value of each node is 1 for other N nodes, and then calculating the resource value of the node, which needs to be allocated to an adjacent node from the own resource values at the current moment, for each node in N +1 nodes through the formula, so that the resource value of the adjacent node is updated to the sum of the resource values allocated to the adjacent node at the next moment of the current moment.
And 104, when the resource value of each node reaches a stable state, selecting an initial source node according to the size relationship of the resource value of each node.
In step 103, the process of allocating resource values to each node is an iterative process, and in this step, the manner of determining whether the resource values of each node reach a stable state may be: judging whether the resource value of each node after the last iteration is the same as the resource value of each node after the current iteration or whether the change value of the resource value of each node after the last iteration and the resource value of each node after the current iteration is within a preset threshold range; if yes, the resource value of each node reaches a stable state.
Further, in this step, the initial source node may be selected according to the size relationship of the resource values of the nodes in the following manner:
when the resource value of each node reaches a stable state, the resource value of the background node is averagely distributed to each node except the background node in the weighted reachable graph, and the final resource value of each node except the background node in the weighted reachable graph is obtained;
and selecting an initial source node according to the magnitude relation of the final resource values of all nodes except the background node in the weighted reachable graph.
For example, if at tcAt the moment, each node reaches a stable state, and the resource value v of the background node is setg(tc) The final resource value V of each node in the steady state is obtained by averagely distributing the resource values to other N nodes except the background nodei(tc) The sum of the resource value of each node in the steady state and the obtained resource value allocated to each node in the steady state of the background node can be expressed as the following formula:
wherein, tcIndicates the time, V, at which each node has reached a steady statei(tc) Final resource value, v, representing each node in steady statei(tc) Resource value, v, representing each node in steady stateg(tc) And the resource value of the background node in a stable state is shown, i represents the serial number of the node, and N represents the number of the nodes for generating the weighted reachable graph in the mobile opportunity network.
Specifically, when selecting the initial source node, the node with the largest final resource value in the steady state may be selected as the initial source node, for example, for the weighted reachable graph shown in fig. 3, resource value allocation is performed according to the resource value allocation policy in step 103, and when the resource value of each node reaches the steady state, if v is the case1Has a final resource value of 1.1713, v2Has a final resource value of 1.2824, v3Has a final resource value of 1.3935, v4Has a final resource value of 1.0046, v5Has a final resource value of 1.2546, v6Is 0.8935, v may be selected3As the initial source node.
When selecting the initial source node, the nodes may be arranged in the order of resource values from large to small, and a preset number of nodes are selected from the nodes as the initial source node, or according to a certain preset percentage of the total number of nodes, for example: 5% from which the node is selected as the initial source node. The specific manner of selecting the initial source node according to the size relationship of the final resource value of each node is not limited herein.
By applying the embodiment shown in fig. 1, in the process of selecting the initial source node, the link change relationship of the mobile opportunity network is considered, and even if the topology structure of the mobile opportunity network changes greatly, the resource value can be allocated based on the weighted reachable graph generated by the link change relationship of the mobile opportunity network, so that the initial source node with strong data transmission capability is selected according to the stabilized resource value of each node, and the data transmission efficiency is improved.
Referring to fig. 2, fig. 2 is another schematic flow chart of a method for selecting an initial source node in mobile opportunistic network traffic offloading according to an embodiment of the present invention, which specifically includes the following steps:
The content of step 201 is the same as that of step 101, and is not described herein again.
The timing path between nodes is directional, e.g. from node v during a predetermined time period1To node vk+1May be denoted as slave node v1To node vk+1A sequential set of a series of nodes [ v ]1,v2,…,vk,vk+1]Wherein v is1Is the starting node of the timing path, vk+1K +1 is the number of nodes constituting the timing path, and k is the number of links formed by the nodes constituting the timing path.
For example, the distance between the nodes in the preset time period is obtained according to the distance change relationship between the nodes, and the nodes v at each moment in the preset time period are respectively judged1And v2Node v2And v3… is less than a preset wireless communication distance R, if at t5Time of day, node v1And v2Is less than R, node v2And v3Is greater than R, then the indication is at t5Time of day, node v1And v2Can communicate between, node v1Information can be delivered to node v2Node v2And v3Can not communicate with each other, and the information reaches the node v2Thereafter, it cannot be transferred to node v3(ii) a And at t5After time, λ has elapsed for a long time, at t6Time of day, node v2And v3Is less than R, at which point node v2And v3Can communicate with each other, node v2Passing information to node v3Then, during the lambda period, i.e. at [ t5,t6]Within a time period, node v1To v3There is a timing path between: v. of1->v2->v3Through the time-sequential path, node v1Can pass its information to node v3。
Or, at t5Time of day, node v1And v2Greater than R, node v2And v3Is less than R, node v1And v2Cannot communicate with each other, node v2And v3Can communicate between, node v3Information can be delivered to node v2Node v2And v1Can not communicate with each other, and the information reaches the node v2Thereafter, it cannot be transferred to node v1(ii) a And at t5After time, λ has elapsed for a long time, at t6Time of day, node v1And v2Is less than R, at which point node v1And v2Can communicate between, node v2Information can be delivered to node v1Then, during the lambda period, i.e. at [ t5,t6]Within a time period, node v3To v1There is a timing path between: v. of3->v2->v1Through the time-sequential path, node v3Can pass its information to node v1。
Furthermore, in [ t5,t6]In time period, if node v1To v3There is a timing path in between, not represented at t5,t6]Within a time period, the slave node v3To v1There must also be a timing path in between.
And step 205, determining the instant path existing between the node and other nodes in the mobile opportunity network at the communication moment according to the distance for each node.
The instantaneous path between nodes being bidirectional, e.g. at the moment of communication, from node viTo node vjCan be represented as a slave node viTo node vjA sequential set of a series of nodes [ v ]i,vi+1,…,vj]Wherein v isiIs the starting node of the transient path, vjIs the termination node of the transient path.
For example, the distance between the nodes in the preset time period is obtained according to the distance change relationship between the nodes, and the nodes v at each moment in the preset time period are respectively judged1And v2Node v2And v3… is less than a preset wireless communication distance R, if at t5Time of day, node v1And v2Is less than R, node v2And v3Also the distance betweenLess than R indicates at t5Time of day, node v1And v2There is a transient path between: v. of1←→v2Through the transient path, node v1And v2Can carry out information transmission between the nodes, and similarly, the node v2And v3There is a transient path between: v. of2←→v3Node v1And v3There is a transient path between: v. of1←→v2←→v3。
And step 206, generating a weighted reachable graph according to the determined time sequence path and the determined transient path.
After the time sequence path and the instantaneous path are determined, generating a weighted reachable graph according to the determined time sequence path and the instantaneous path; wherein, the unidirectional connecting lines among the nodes in the weighted reachable graph represent time sequence paths, and the bidirectional connecting lines among the nodes in the weighted reachable graph represent transient paths.
For example, the predetermined time period is set as [ t ]1,tk]According to mobile opportunistic network model
Definition of
For the mobile opportunistic network model during the time period t1,tk]Weighted reachability graph in which nodes are aggregated
Is that
Represents a mobile opportunistic network model over a preset time period
Node in, and collection of links
Indicating a preset timeIntra-segment mobile opportunistic network model
A collection of timing paths and transient paths present in (a). That is, if
Node u may opportunistically communicate with node v along a time-sequential path or nodes u and v may be able to establish a transient path at a certain time. How to construct a given time period
The reachability graph of (a) then requires computation of the temporal and instantaneous paths between any two mobile nodes within a given time period. If a timing path exists between two nodes u and v, then two nodes u and v are added to the reachability graph, along with an edge from u to v, until all pairs of nodes for which a timing path exists are added to the reachability graph. If a transient path exists between nodes, a bidirectional edge is added between the two nodes.
For ease of understanding, a specific embodiment for generating a weighted reachability graph is described below by way of specific examples:
let us assume at t5Time of day, node v1To v2Is less than R, node v is connected1And node v2Added to the weighted reachability graph and at node v1And node v2Adds a bidirectional edge between them, and assumes node v2And v3The distance between the nodes is greater than R, the node v is not added3(ii) a If at t5T after the moment6Time of day, node v2And v3Is less than R, node v is connected3Also added to the weighted reachability graph and at node v2And node v3A bidirectional edge is added between the two edges, since at t5,t6]Within a time period, the slave node v1To v3There is a timing path between them, therefore, one slave node v is added1To node v3Has a directed edge. In this manner, the user can easily and accurately select the desired target,until all nodes with time sequence paths and instantaneous paths in a preset time period in the mobile opportunity network are added into the weighted reachable graph, a preset time period [ t ] is generated5,t6]A weighted reachability graph within that contains the timing path, transient path, and all nodes where the timing path and transient path exist.
FIG. 3 is a diagram of a weighted reachability graph generated from 6 nodes and 12 directed links, where v is1～v6Indicating nodes where a timing path and an instantaneous path exist, a unidirectional edge between two nodes indicating a link in the timing path existing between the two nodes, a bidirectional edge indicating an instantaneous path existing between the two nodes, numbers on the unidirectional edge and the bidirectional edge indicating a weight which is the sum of the number of timing paths and instantaneous paths existing between the two nodes of the link within a preset time period.
And step 207, dynamically allocating the resource values of the nodes according to a preset resource value allocation strategy based on the weighted reachable graph.
And 208, when the resource value of each node reaches a stable state, selecting an initial source node according to the size relationship of the resource value of each node.
The contents of step 207 and step 208 are the same as those of step 103 and step 104, respectively, and are not described again here.
By applying the embodiment shown in fig. 2, in the process of selecting the initial source node, the link change relationship of the mobile opportunistic network is considered, and even if the topology structure of the mobile opportunistic network changes greatly, the resource value can be allocated based on the weighted reachable graph generated by the link change relationship of the mobile opportunistic network, so that the initial source node with strong data transmission capability is selected according to the stabilized resource value of each node, and the data transmission efficiency is improved.
Further, corresponding to the above method embodiment, the present invention also provides a device for selecting an initial source node in mobile opportunistic network traffic offloading, as shown in fig. 4, where the device may include:
an obtaining module 401, configured to obtain a link change relationship between nodes in a preset time period in a mobile opportunity network, where in the preset time period, the mobile opportunity network includes a preset number of nodes;
a weighted reachability graph generation module 402, configured to generate a weighted reachability graph according to the link change relationship; the weighted reachability graph is a directed network graph formed by nodes and edges, the nodes in the weighted reachability graph represent the nodes contained in the mobile opportunity network, and the edges in the weighted reachability graph represent the link change relationship among the nodes;
a resource value allocation module 403, configured to dynamically allocate a resource value of each node according to a preset resource value allocation policy based on the weighted reachability graph;
an initial source node selecting module 404, configured to select an initial source node according to a size relationship of the resource values of the nodes when the resource values of the nodes reach a stable state.
Further, the weighted reachability graph generation module 402 includes: a time sequence path determining submodule, an instantaneous path determining submodule and a weighted reachability graph generating submodule;
the time sequence path determining submodule is used for determining a time sequence path between each node and other nodes in the mobile opportunity network in the preset time period according to the link change relation;
the instantaneous path determining submodule is used for determining an instantaneous path between each node and other nodes in the mobile opportunity network according to the link change relation;
and the weighted reachability graph generation submodule is used for generating a weighted reachability graph according to the determined time sequence path and the determined instantaneous path.
Further, the time sequence path determining submodule is specifically configured to obtain a distance change relationship between nodes in the preset time period according to the link change relationship; and for each node, determining a time sequence path existing between the node and other nodes in the mobile opportunity network in the preset time period according to the distance change relation.
Further, a unidirectional edge between nodes in the weighted reachability graph represents a temporal path, and a bidirectional edge between nodes in the weighted reachability graph represents a temporal path;
the resource value allocation module 403 includes: a background node adding submodule, an initial resource value setting submodule and a resource value dynamic allocation submodule;
the background node adding submodule is used for adding background nodes in the weighted reachable graph and establishing instantaneous paths between the background nodes and each node in the weighted reachable graph;
the initial resource value setting submodule is configured to set the initial resource value of the background node to 0, and set the initial resource value of each node except the background node in the weighted reachability graph to a unit resource value;
the resource value dynamic allocation submodule is configured to dynamically allocate the resource value of each node according to the following formula:
wherein, the node viIs a node vjA neighbor node of vj(t) denotes the node v at time tjResource value of vi(t +1) represents the node v at time t +1iResource value of, wjiRepresenting a slave node vjTo node viWeight on directed edges, wjiIs equal to the node v within the preset time periodjAnd node viSum of the number of time-series paths and transient paths existing in between, sumw (j) represents the node vjThe sum of the weights of all the outgoing edges, wherein N represents the number of nodes for generating the weighted reachable graph in the mobile opportunity network;
the initial source node selection module 404 is specifically configured to: when the resource value of each node reaches a stable state, the resource value of the background node is averagely distributed to each node except the background node in the weighted reachable graph, and the final resource value of each node except the background node in the weighted reachable graph is obtained; and selecting an initial source node according to the magnitude relation of the final resource values of all nodes except the background node in the weighted reachable graph.
By applying the embodiment described in fig. 4, in the process of selecting the initial source node, the link change relationship of the mobile opportunistic network is considered, and even if the topology structure of the mobile opportunistic network changes greatly, the resource value can be allocated based on the weighted reachable graph generated by the link change relationship of the mobile opportunistic network, so that the initial source node with strong data transmission capability is selected according to the stabilized resource value of each node, and the data transmission efficiency is improved.
Based on the same inventive concept, the method for selecting an initial source node in mobile opportunistic network traffic offloading provided by the above embodiment of the present invention correspondingly provides an electronic device, as shown in fig. 5, including a processor 501, a communication interface 502, a memory 503 and a communication bus 504, where the processor 501, the communication interface 502 and the memory 503 complete communication with each other through the communication bus 504,
a memory 503 for storing a computer program;
the processor 501 is configured to, when executing the program stored in the memory 503, implement the method for selecting an initial source node in mobile opportunistic network traffic offloading provided by the embodiment of the present invention.
For example, the following steps may be included:
acquiring a link change relation between nodes in a mobile opportunity network within a preset time period, wherein the mobile opportunity network comprises a preset number of nodes within the preset time period;
generating a weighted reachable graph according to the link change relationship; the weighted reachability graph is a directed network graph formed by nodes and edges, the nodes in the weighted reachability graph represent the nodes contained in the mobile opportunity network, and the edges in the weighted reachability graph represent the link change relationship among the nodes;
based on the weighted reachable graph, dynamically allocating the resource values of the nodes according to a preset resource value allocation strategy;
and when the resource value of each node reaches a stable state, selecting an initial source node according to the size relationship of the resource value of each node.
Further, other processing flows in the method for selecting an initial source node in mobile opportunistic network traffic offloading provided by the embodiment of the present invention may also be included, and are not described in detail herein.
The communication bus mentioned in the electronic device may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The communication bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown, but this does not mean that there is only one bus or one type of bus.
The communication interface is used for communication between the electronic equipment and other equipment.
The Memory may include a Random Access Memory (RAM) or a Non-Volatile Memory (NVM), such as at least one disk Memory. Optionally, the memory may also be at least one memory device located remotely from the processor.
The Processor may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; but may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component.
In yet another embodiment of the present invention, there is also provided a computer-readable storage medium having stored therein instructions, which when run on a computer, cause the computer to perform the method for selecting an initial source node in mobile opportunistic network traffic offloading as described in any of the above embodiments.
In yet another embodiment of the present invention, there is also provided a computer program product containing instructions which, when run on a computer, cause the computer to perform the method for initial source node selection in mobile opportunistic network traffic offloading as described in any of the above embodiments.
In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. The procedures or functions described above in accordance with the embodiments of the invention may be generated, in whole or in part, when the computer program instructions described above are loaded and executed on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wirelessly (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that includes one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the device and electronic apparatus embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference may be made to some descriptions of the method embodiments for relevant points.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. A method for selecting an initial source node in mobile opportunistic network traffic offloading, the method comprising:
acquiring a link change relationship between nodes in a preset time period in a mobile opportunity network, wherein the mobile opportunity network comprises a preset number of nodes in the preset time period, the mobile opportunity network is a communication network formed by mobile terminals, or the mobile opportunity network is a vehicle-mounted network, when the distance between two nodes is smaller than a preset wireless communication distance, the two nodes are communicated with each other, and the link relationship between the two nodes is changed from the link relationship not existing to the link relationship existing;
generating a weighted reachable graph according to the link change relationship; the weighted reachability graph is a directed network graph formed by nodes and edges, the nodes in the weighted reachability graph represent the nodes contained in the mobile opportunity network, and the edges in the weighted reachability graph represent the link change relationship among the nodes;
based on the weighted reachable graph, dynamically allocating the resource values of the nodes according to a preset resource value allocation strategy;
when the resource value of each node reaches a stable state, selecting an initial source node according to the magnitude relation of the resource value of each node;
wherein, the step of dynamically allocating the resource value of each node according to a preset resource value allocation strategy based on the weighted reachable graph comprises:
adding background nodes in the weighted reachable graph, and establishing transient paths between the background nodes and each node in the weighted reachable graph;
setting the initial resource value of the background node to be 0, and setting the initial resource value of each node except the background node in the weighted reachable graph to be a unit resource value;
and dynamically allocating the resource value of each node according to the following formula:
wherein, the node viIs a node vjA neighbor node of vj(t) denotes the node v at time tjResource value of vi(t +1) represents the node v at time t +1iResource value of, wjiRepresenting a slave node vjTo node viWeight on directed edges, wjiIs equal to the node v within the preset time periodjAnd node viSum of the number of time-series paths and transient paths existing in between, sumw (j) represents the node vjThe sum of the weights of all the outgoing edges, wherein N represents the number of nodes for generating the weighted reachable graph in the mobile opportunity network;
when the resource value of each node reaches a stable state, the step of selecting an initial source node according to the magnitude relation of the resource values of each node comprises the following steps:
when the resource value of each node reaches a stable state, the resource value of the background node is averagely distributed to each node except the background node in the weighted reachable graph, and the final resource value of each node except the background node in the weighted reachable graph is obtained;
and selecting an initial source node according to the magnitude relation of the final resource values of all nodes except the background node in the weighted reachable graph.
2. The method of claim 1, wherein the step of generating a weighted reachability graph based on the link change relationship comprises:
for each node, determining a time sequence path between the node and other nodes in the mobile opportunity network in the preset time period according to the link change relation;
for each node, determining an instantaneous path between the node and other nodes in the mobile opportunity network according to the link change relationship;
a weighted reachability graph is generated based on the determined timing path and transient path.
3. The method according to claim 2, wherein the step of determining, for each node, a timing path between the node and other nodes in the mobile opportunistic network within the preset time period according to the link change relationship comprises:
acquiring the distance change relation between each node in the preset time period according to the link change relation;
and for each node, determining a time sequence path existing between the node and other nodes in the mobile opportunity network in the preset time period according to the distance change relation.
4. The method of claim 3, wherein the step of determining, for each node, the instantaneous path between the node and other nodes in the mobile opportunity network based on the link change relationship comprises:
acquiring the distance between each node at the communication moment in the preset time period according to the link change relation; the communication time is the time point of establishing communication between the nodes;
and determining the instant path existing between the node and other nodes in the mobile opportunity network at the communication moment according to the distance for each node.
5. The method of claim 2, wherein the unidirectional edges between nodes in the weighted reachability graph represent temporal paths and the bidirectional edges between nodes in the weighted reachability graph represent temporal paths.
6. An apparatus for selecting an initial source node in mobile opportunistic network traffic offloading, the apparatus comprising:
an obtaining module, configured to obtain a link change relationship between nodes in a preset time period in a mobile opportunity network, where in the preset time period, the mobile opportunity network includes a preset number of nodes, and the mobile opportunity network is a communication network formed by mobile terminals, or the mobile opportunity network is a vehicle-mounted network, and when a distance between two nodes is smaller than a preset wireless communication distance, the two nodes perform communication with each other, and a link relationship between the two nodes is changed from an absence of the link relationship to an existence of the link relationship;
the weighted reachability graph generation module is used for generating a weighted reachability graph according to the link change relation; the weighted reachability graph is a directed network graph formed by nodes and edges, the nodes in the weighted reachability graph represent the nodes contained in the mobile opportunity network, and the edges in the weighted reachability graph represent the link change relationship among the nodes;
the resource value allocation module is used for dynamically allocating the resource values of the nodes according to a preset resource value allocation strategy based on the weighted reachable graph;
the initial source node selection module is used for selecting an initial source node according to the size relationship of the resource values of the nodes when the resource values of the nodes reach a stable state;
wherein the resource value allocation module includes: a background node adding submodule, an initial resource value setting submodule and a resource value dynamic allocation submodule;
the background node adding submodule is used for adding background nodes in the weighted reachable graph and establishing instantaneous paths between the background nodes and each node in the weighted reachable graph;
the initial resource value setting submodule is configured to set the initial resource value of the background node to 0, and set the initial resource value of each node except the background node in the weighted reachability graph to a unit resource value;
the resource value dynamic allocation submodule is configured to dynamically allocate the resource value of each node according to the following formula:
wherein, the node viIs a node vjA neighbor node of vj(t) denotes the node v at time tjResource value of vi(t +1) represents the node v at time t +1iResource value of, wjiRepresenting a slave node vjTo node viWeight on directed edges, wjiIs equal to the node v within the preset time periodjAnd node viSum of the number of time-series paths and transient paths existing in between, sumw (j) represents the node vjThe sum of the weights of all the outgoing edges, wherein N represents the number of nodes for generating the weighted reachable graph in the mobile opportunity network;
the initial source node selection module is specifically configured to: when the resource value of each node reaches a stable state, the resource value of the background node is averagely distributed to each node except the background node in the weighted reachable graph, and the final resource value of each node except the background node in the weighted reachable graph is obtained; and selecting an initial source node according to the magnitude relation of the final resource values of all nodes except the background node in the weighted reachable graph.
7. The apparatus of claim 6, wherein the weighted reachability graph generation module comprises: a time sequence path determining submodule, an instantaneous path determining submodule and a weighted reachability graph generating submodule;
the time sequence path determining submodule is used for determining a time sequence path between each node and other nodes in the mobile opportunity network in the preset time period according to the link change relation;
the instantaneous path determining submodule is used for determining an instantaneous path between each node and other nodes in the mobile opportunity network according to the link change relation;
and the weighted reachability graph generation submodule is used for generating a weighted reachability graph according to the determined time sequence path and the determined instantaneous path.
8. The apparatus according to claim 7, wherein the timing path determining submodule is specifically configured to obtain, according to the link change relationship, a distance change relationship between nodes in the preset time period; and for each node, determining a time sequence path existing between the node and other nodes in the mobile opportunity network in the preset time period according to the distance change relation.
9. The apparatus of claim 7, wherein unidirectional edges between nodes in the weighted reachability graph represent timing paths and bidirectional edges between nodes in the weighted reachability graph represent transient paths.
10. An electronic device is characterized by comprising a processor, a communication interface, a memory and a communication bus, wherein the processor and the communication interface are used for realizing mutual communication by the memory through the communication bus;
a memory for storing a computer program;
a processor for implementing the method steps of any one of claims 1 to 5 when executing a program stored in the memory.
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