CN113179484B - IDNC network coding method based on Internet of vehicles model - Google Patents

IDNC network coding method based on Internet of vehicles model Download PDF

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CN113179484B
CN113179484B CN202110466583.7A CN202110466583A CN113179484B CN 113179484 B CN113179484 B CN 113179484B CN 202110466583 A CN202110466583 A CN 202110466583A CN 113179484 B CN113179484 B CN 113179484B
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rsuc
vehicle
ijk
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CN113179484A (en
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梅中辉
周根
徐礼建
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Nanjing University of Posts and Telecommunications
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Nanjing University of Posts and Telecommunications
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/02—Services making use of location information
    • H04W4/021—Services related to particular areas, e.g. point of interest [POI] services, venue services or geofences
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/06—Testing, supervising or monitoring using simulated traffic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/0226—Traffic management, e.g. flow control or congestion control based on location or mobility
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/0231—Traffic management, e.g. flow control or congestion control based on communication conditions
    • H04W28/0236—Traffic management, e.g. flow control or congestion control based on communication conditions radio quality, e.g. interference, losses or delay
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/06—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/02—Services making use of location information
    • H04W4/025—Services making use of location information using location based information parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/40—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P]
    • H04W4/44—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P] for communication between vehicles and infrastructures, e.g. vehicle-to-cloud [V2C] or vehicle-to-home [V2H]

Abstract

The application provides an IDNC network coding method based on an Internet of vehicles model, which comprises the following steps that (1) each RSU estimates the probability that each vehicle node in the coverage area of a transmitting signal is in different coverage areas at the position of the transmitting time slot of the next data packet; each RSU constructs an IDNC coding relation diagram corresponding to the RSU; constructing a maximum weight group by each RSU based on data packets required to be received by all vehicle nodes in the coverage area of the signal transmitted by each RSU; step (3): each RSU carries out IDNC coding according to the data packet corresponding to the node in the maximum weight group, and the node which participates in the coding is deleted from the IDNC coding relation diagram; step (4): if the node set in the IDNC coding relation diagram is a non-empty subset, the step (1) is switched to iterative operation until the node set in the IDNC coding relation diagram is empty. The application can improve the throughput of the data of the Internet of vehicles and reduce the network decoding time delay.

Description

IDNC network coding method based on Internet of vehicles model
Technical Field
The application relates to an IDNC network coding method based on a car networking model, and belongs to the field of car networking and network coding.
Background
The internet of vehicles (Internet of Vehicles) is a vast interactive network consisting of information on vehicle location, speed, route, etc. The internet of vehicles communication includes communication (V2I) between infrastructure (RSU) and vehicles, communication (V2V) between vehicles, communication (V2P) between vehicles and pedestrians, and the like. The internet of vehicles can realize an integrated network of intelligent traffic management, intelligent dynamic information service and intelligent control of vehicles.
Compared with the traditional routing technology, the network coding technology carries out forwarding after coding the data packet at the intermediate node, and can correspondingly utilize redundant information in the network to improve the network data throughput. For the traditional deterministic network coding technology and random network coding technology, a receiving end must receive enough data packets with coding coefficients not linearly related to complete network decoding, so that network decoding delay exists and the real-time transmission performance of the data packets is affected.
Because of special application scenes of the Internet of vehicles, particularly application scenes of communication (V2I) between infrastructure (RSU) and vehicles, considering that a plurality of RSUs send data packets to a plurality of vehicles and that the RSU transmits signals to cross and cover the vehicles, different coding modes have great influence on the transmission performance and throughput of the system, so how to select the network coding mode of the RSU end to reduce network transmission delay and improve the throughput of the system is a technical problem to be solved in the field.
Disclosure of Invention
The application aims to provide a network coding method based on a car networking model, which reduces network transmission delay and improves system throughput.
In order to achieve the technical purpose, the application adopts the following technical scheme.
The IDNC network coding method based on the Internet of vehicles model comprises the following steps:
estimating the probability that each vehicle node in the coverage area of a transmitting signal of each RSU is in different coverage areas at the position of the next data packet transmitting time slot; each RSU constructs an IDNC coding relation diagram corresponding to the RSU according to the probability that the positions of the vehicle nodes are in different coverage areas, the data packet information which the vehicle nodes need to receive and the IDNC network coding conditions;
constructing a maximum weight group by each RSU based on data packet information required to be received by all vehicle nodes in the coverage area of the signal transmitted by each RSU and an IDNC coding relation diagram;
step (3): each RSU carries out IDNC coding according to the data packet corresponding to the node in the maximum weight group, and the node which participates in the coding is deleted from the IDNC coding relation diagram;
step (4): if the node set in the IDNC coding relation diagram is a non-empty subset, the step (1) is switched to iterative operation until the node set in the IDNC coding relation diagram is empty.
Further, the method for constructing the IDNC coding relation diagram corresponding to each RSU specifically comprises the following steps: determining a node, an IDNC interference edge and a transmitting signal interference edge; if the vehicle node v j From RSUc i Receiving data packet a k With vehicle node v j' From RSUc i Receiving data packet a k' If the IDNC coding condition is not satisfied, node n ijk And node n ij'k' IDNC interference edges exist between the two; vehicle node v j Fall to RSUc i With RSUc i' Cross coverage area, node n ijk And node n i'jk' A transmitting signal interference side exists between the two; vehicle node v j Fall to RSUc i With RSUc i' Cross coverage area, vehicle node v j' Fall on RSUc only i' Within the coverage area, node n ijk And node n i'j'k' A transmitting signal interference side exists between the two; vehicle node v j With vehicle node v j' All fall on RSUc i With RSUc i' Cross coverage area, node n ijk And node n i'j'k' Between which there are transmitting signal interference edges, node n i'jk And node n ij'k' A transmitting signal interference side exists between the two; wherein node n ijk Indicating that it falls on RSUc i Vehicle node v within coverage area j The data packet a needs to be received k Node n ij'k' Indicating that it falls on RSUc i Vehicle node v within coverage area j' The data packet a needs to be received k' ；n i'jk' Indicating that it falls on RSUc i' Vehicle node v within coverage area j The data packet a needs to be received k' The method comprises the steps of carrying out a first treatment on the surface of the Node n i'jk Indicating that it falls on RSUc i' Vehicle node v within coverage area j The data packet a needs to be received k Node n i'j'k' Indicating that it falls on RSUc i' Vehicle node v within coverage area j' The data packet a needs to be received k' 。
Further, step (2) includes:
step 201: each RSU constructs a corresponding maximum weight group based on data packet information which is only required to be received by a vehicle node covered by an own transmitting signal in an IDNC coding relation diagram;
step 202: based on the data packet information which is required to be received by all vehicle nodes corresponding to all vehicles in the cross coverage area of the self-transmitted signal and other RSU transmitted signals in the IDNC coding relation diagram, each RSU sequentially selects the node with the largest node weight in each cross coverage area, and classifies the node into the largest weight group corresponding to each RSU.
Still further, the specific method of step 201 includes:
by RSUc i The IDNC coding relation diagram corresponding to the data packet required to be received by the covered vehicle node is G, and G is taken s ＝G，Representing a certain RSUc i Selecting a maximum weight group from the corresponding IDNC graph;
iterative operation: updating node weight and taking the node with the maximum weightUpdate->
Node is connected withFrom G s Delete and will be associated with node->Node n with connecting edges i'j'k' Has a deletion probability of alpha ijk,i'j'k' The method comprises the steps of carrying out a first treatment on the surface of the If->Continuing the iterative operation, wherein α ijk,i'j'k' Representing node n ijk And node n ij'k' Indian IDNC trunkScrambling edge weight, node n according to IDNC coding condition ijk And node n ij'k' With connecting edges between them, alpha ijk,i'j'k' =1, otherwise α ijk,i'j'k' ＝0。
Still further, the vehicle node v j Fall on only one RSUc i The product of the probability in coverage and the number of packets that the vehicle node needs to receive is taken as n ijk Node weight of (2), node n ijk The node weights of (a) are expressed as: w (w) ijk ＝x ij ·|ψ j |；x ij Representing vehicle node v j Fall on only one RSUc i Probability in coverage, |ψ j I represents the vehicle node v j The number of packets required to be received.
Further, each RSU estimates the next data packet transmission time slot vehicle node v according to the current position of each vehicle node and the vehicle running speed in the coverage area of the transmission signal j Fall on only one RSUc i Probability x within coverage ij The expression is as follows:
wherein RSUc i The coordinate position in the plane isVehicle node v j The coordinate position of (b) x ,b y ) The running speed was ∈ x ,ε y )，R i Representing RSUc i The radius of the communication range area which can be covered, t represents the length of the transmission time slot of the data packet.
Further, the formula for updating the node weights is expressed as:
wherein alpha is ijk,i'j'k' Representing node n ijk And node n i'j'k' Inter IDNC interference side weightsHeavy, node n ijk Indicating that it falls on RSUc i Vehicle node v within coverage area j The data packet a needs to be received k Node n i'j'k' Indicating that it falls on RSUc i' Vehicle node v within coverage area j' The data packet a needs to be received k' ，w ijk Representing node n ijk Weights, w i ' jk Representing node n ijk Updated weights, w i'j'k' Representing node n i'j'k' Node weight of (2), node n ijk And node n i'j'k' With connecting edges between them, alpha ijk,i'j'k' =1, otherwise α ijk,i'j'k' ＝0。
Further, the specific method in step 202 is as follows:
determining node weights of nodes in the cross coverage positions;
according to IDNC coding conditions, if all nodes in the node with the largest weight in the cross coverage area and the maximum weight group corresponding to the RSU covering the node do not have IDNC interference connection edges or transmitting signal interference connection edges, the node can be classified into the maximum weight group corresponding to the RSU;
if the node with the greatest weight in the intersection location cannot be categorized into the largest weight group in any RSU covering it, that node constitutes an independent weight maximum group.
Further, the weight of the node in the cross-over position is denoted as w ii'jk ＝y ii'j ·|ψ j I, wherein w ii'jk Representing node n ii'jk Weight of node n ii'jk Indicating that it falls on RSUc i With RSUc i' Vehicle node v in cross coverage j The data packet a needs to be received k ，y ii'j Representing vehicle node v j Fall to RSU c i With RSUc i' Probability in cross coverage, |ψ j I represents the vehicle node v j The number of data packets required.
Still further, y ii'j Representing vehicle node v j Fall to RSUc i With RSUc i' Probability in cross coverage, expressed as follows:
wherein RSUc i' The coordinate position in the plane isR i' Representing RSUc i' Radius of communication range area that can be covered.
The application also provides a computer readable storage medium storing a computer program which when executed by a processor implements the steps of the network coding method based on the internet of vehicles model as provided in any one of the possible embodiments of the technical scheme.
The beneficial technical effects obtained by the application are as follows:
the method fully considers the condition that a plurality of RSUs send data packets to a plurality of vehicles, provides the network coding method for the vehicle networking model, is suitable for the application scene of communication (V2I) between an infrastructure (RSU) and the vehicles, and can reduce network decoding delay while improving the vehicle networking data throughput.
Drawings
Fig. 1 is a schematic flow chart of constructing a maximum weight group of a network coding method based on an internet of vehicles model according to an embodiment;
FIG. 2 is a diagram of a conventional IDNC;
FIG. 3 is a diagram of an example system of embodiments;
fig. 4 is a weight-based IDNC diagram constructed by the network coding method based on the car networking model according to the embodiment.
Detailed Description
The application is further described below with reference to the drawings and specific examples.
Because of special application scenes of the Internet of vehicles, particularly application scenes of communication (V2I) between infrastructure (RSU) and vehicles, the condition that the RSU transmits signals to cover vehicles in a crossing way is considered to send data packets to a plurality of vehicles by a plurality of RSUs, and different coding modes have great influence on the transmission performance and throughput of the system. The instantaneous decoding network coding (Instantly decodable network coding, IDNC) method selects corresponding data packets to carry out network coding according to the received and to-be-received data packet information fed back from the receiving end, thereby ensuring that the receiving end can immediately carry out network decoding, reducing network decoding delay and improving the real-time transmission performance of data. The IDNC real-time decoding characteristic can be utilized in the technical field of the Internet of vehicles, so that the decoding delay is reduced, and the time slot required by data transmission of the system can be reduced, thereby improving the data throughput of the system. However, there is no application example of the internet of vehicles to which the IDNC is applied, and how to implement network coding of the internet of vehicles based on the IDNC to reduce network transmission delay and improve system throughput is a technical problem to be solved in the art.
The application provides a method for instantaneous decoding network coding (Instantly decodable network coding, IDNC) based on a vehicle networking system, which considers that a plurality of RSUs send data packets to a plurality of vehicle nodes at the same time, and the vehicle nodes can be divided into: covered by a single RSU, covered by two adjacent RSUs, and not covered by RSUs. Vehicles covered by two adjacent RSUs cannot simultaneously receive signals sent by the two RSUs, and data received from the corresponding RSUs is selected according to the condition that the time slot required for overall data transmission is minimum.
Constructing an IDNC coding diagram according to IDNC coding conditions and signal conditions that a vehicle covered by two adjacent RSUs cannot simultaneously receive data transmitted by the two RSUs, firstly selecting a maximum weight group corresponding to the condition that the vehicle nodes in the coverage area of a single RSU receive data in the diagram according to the diagram, and then selecting the nodes corresponding to the vehicle nodes covered by the two adjacent RSUs in the IDNC diagram according to the connecting edges in the diagram to be added into the maximum weight group. And finally, the data packet corresponding to the node in the maximum weight group is the IDNC network coding data packet.
Example 1: an instantaneous decoding network coding method based on an internet of vehicles model comprises the following steps:
estimating the probability that each vehicle node in the coverage area of a transmitting signal of each RSU is in different coverage areas at the position of the next data packet transmitting time slot;
constructing an IDNC coding relation diagram corresponding to the RSU according to the probability that the positions of the vehicle nodes are in different coverage areas, the data packet information which the vehicle nodes need to receive and the IDNC network coding conditions;
the different coverage areas include: vehicle node v j Fall on only one RSUc i In-coverage, vehicle node v j Fall to RSUc i With RSUc i' Cross-coverage in-and-vehicle node v j Is not covered by any RSU. Considering the probability that the locations of the vehicle nodes are in different coverage areas includes:
each RSU estimates the next data packet sending time slot vehicle node v according to the current position of each vehicle node and the vehicle running speed in the coverage area of the transmitting signal j Fall on only one RSUc i Probability x within coverage ij ，RSUc i The coordinate position in the plane isVehicle node v j The coordinate position of (b) x ,b y ) The running speed was ∈ x ,ε y )，R i Representing a preset RSU c i Coverage of communication range area radius, i.e. with RSUc i Less than R apart i Can correspondingly receive the data transmitted by the RSU, then +.>
The IDNC coding condition is that the coded data packet can be immediately subjected to network decoding at the receiving end. The method for constructing the corresponding IDNC coding relation diagram of the RSU comprises the following steps:
each RSU considers the vehicle nodes within the coverage area of its own transmitted signal, i.e. including both vehicle nodes covered by the RSU only and also by the RSU transmitted signal at the same timeA cover and a vehicle node in another adjacent RSU transmitting signal cross coverage area construct a corresponding IDNC coding relation diagram, wherein a certain RSUc i The method for specifically constructing the IDNC coding relation diagram comprises the following steps:
(1) Node n ijk : indicating that it falls on RSUc i Vehicle node v within coverage area j The data packet a needs to be received k ；
(2) IDNC interference edge: if the IDNC coding conditions are met, vehicle node v j From RSUc i Receiving data packet a k With vehicle node v j' From RSUc i Receiving data packet a k' Cannot be performed simultaneously, node n ijk And node n ij'k' Interference connecting edges exist between the two connecting edges;
(3) Connecting edges: vehicle node v j Fall to RSUc i With RSUc i' Cross coverage area, node n ijk And node n i'jk' A connecting edge exists between the two connecting edges;
(4) Transmitting signal interference side: vehicle node v j With vehicle node v j' All fall on RSUc i With RSUc i' Cross coverage area, node n ijk And node n i'j'k' Between which there are transmitting signal interference edges, node n i'jk And node n ij'k' A transmitting signal interference side exists between the two; vehicle node v j Fall to RSUc i And RSU c i' Cross coverage area, vehicle node v j' Fall on RSUc only i' Within the coverage area, node n ijk And node n i'j'k' There is a transmit signal interference edge between. Vehicle node v j Fall to RSUc i With RSUc i' Cross coverage area, node n ijk And node n i'jk' There is a transmit signal interference edge between.
(5) Node weight: alternatively, in the embodiment, the node weight is defined as the product of the number of data packets required by the vehicle node and the link reliability, that is, the number of data packets required by the vehicle node and the vehicle node v j Fall on only one RSUc i The product of probabilities within the coverage area, node n ijk The weight is w ijk ＝x ij ·|ψ j |；Defining node weight in the IDNC as the number of data packets required to be received by the vehicle nodes, namely, the vehicle nodes with more data packets to be received have larger weight and are preferentially considered to receive the data, so that the data transmission time slot is reduced;
(6) IDNC interference edge weight: node n according to IDNC coding conditions ijk And node n ij'k' With connecting edges between them, alpha ijk,i'j'k' =1; otherwise alpha ijk,i'j'k' =0; and (2) constructing a maximum weight group by each RSU based on the data packets which all vehicle nodes in the coverage area of the self-transmitted signal need to receive, wherein the RSU comprises the following steps: each RSU considers vehicle nodes covered by the self-transmitted signals in the IDNC coding relation diagram, and does not consider nodes and connecting edges corresponding to the vehicle nodes in the cross coverage area, so as to construct a maximum weight group; and (2) sequentially selecting nodes with the largest weight for the nodes corresponding to the data packets which are needed to be received by the vehicle nodes in the cross coverage area in the IDNC graph, and classifying the nodes into the largest weight groups corresponding to the RSUs obtained in the step (2).
Each RSU considers vehicle nodes covered by the self-transmitted signals in the IDNC coding relation diagram, and does not consider nodes and connecting edges corresponding to the vehicle nodes in the cross coverage area, so as to construct the maximum weight group. Consider a certain RSUc therein i The corresponding IDNC diagram selects the maximum weight groupThe flow chart is shown in fig. 1, and the specific method comprises the following steps:
the first step: initializing;
assuming to be RSUc i The corresponding IDNC diagram of the covered vehicle node is G, and G is taken out s ＝G；
Recording the selected node set asAnd initialize +.>
And a second step of: performing iterative operation;
updating node weights:
weight-taking maximum nodeUpdate->
Node is connected withFrom G s Delete and will be associated with node->Node n with connecting edges i'j'k' Has a deletion probability of alpha ijk,i'j'k' ；
If it isContinuing the iterative operation until ++>
Sequentially selecting nodes with the largest weight for the nodes corresponding to the vehicle nodes in the cross coverage area in the IDNC graph, and classifying the nodes into the largest weight groups corresponding to the RSUs obtained in the step (2), wherein the specific method comprises the following steps:
the weight of a node in a cross-over position may be defined as w ii'jk ＝y ii'j ·|ψ j I (I); wherein the method comprises the steps ofWherein RSUc i' The coordinate position in the plane is +.>R i' Representing RSUc i' Coverage area of communication rangeDomain radius.
Suppose vehicle node v j The position is simultaneously covered by RSUc i And RSUc i' Covered, consider vehicle node v j Data packet a needs to be received k Since the vehicle node can be selected from RSUc i The data packet is received, or from RSUc i' Receiving the packet, i.e. in IDNC diagram can be expressed as n ijk May also be expressed as n i'jk . If n ijk And ball(s)None of the intermediate nodes has a connecting edge, which can be expressed as n ijk And n is as follows ijk Adding radix et caulis Periplocae Calophyllae>Similarly, if n i'jk With (1) block->None of the intermediate nodes has a connecting edge, which can be expressed as n i'jk And n is as follows i'jk Adding radix et caulis Periplocae Calophyllae>If n i'jk With (1) block->None of the nodes has a connecting edge, and n ijk With (1) block->The nodes have no connecting edges, and the group +.>Or (1) group->Adding; if n i'jk With (1) block->The middle node has a connecting edge, and n ijk With (1) block->And if the middle node has a connecting edge, discarding the classification of the node in the cross coverage area, and continuously considering the next node in the cross coverage area to classify.
Step (3): each RSU selects a subset of the vehicle nodes with the maximum weight from the maximum weight group to carry out IDNC coding, and deletes the nodes which participate in the coding from the IDNC coding relation diagram;
step (4): if the node set in the IDNC coding relation diagram is a non-empty subset, the step (1) is switched to iterative operation until the node set in the IDNC coding relation diagram is empty.
Fig. 3 is an exemplary diagram. In this example there are two RSUs, RSUc 1 With RSUc 2 5 data packets a 1 ,a 2 ,a 3 ,a 4 ,a 5 Broadcast to 6 vehicles v 1 ,v 2 ,v 3 ,v 4 ,v 5 ,v 6 For simplicity, it is assumed that the specific location of each vehicle, x, can be accurately determined 11 ＝x 12 ＝x 13 ＝1，x 25 ＝x 26 ＝1，y 12,4 =1. And presumes the vehicle node v 1 Data packet a has not been received 3 Vehicle node v 2 Data packet a has not been received 1 Vehicle node v 3 Data packet a has not been received 1 Vehicle node v 4 Data packet a has not been received 2 And a 3 Vehicle node v 5 Data packet a has not been received 4 Vehicle node v 6 Data packet a has not been received 5 And it is assumed that this information can be accurately fed back to the RSU through a feedback channel.
According to the conventional IDNC coding method, the corresponding IDNC diagram is shown in FIG. 2, in which node n ijk Representing vehicle node v j To be from RSUc i Receiving data packet a k . Node n 254 And node n 142 And n 143 Between which there are transmitting signal interference connecting edges, node n 265 And noden 142 And n 143 There is also a transmit signal interference connection edge between. Node n 142 And n 143 There is an IDNC interference connection edge between them.
Based on the IDNC diagram of the traditional IDNC coding mode, node n in a dotted line frame 113 ，n 121 ，n 131 ，n 254 ，n 265 The maximum coding subset (the maximum coding subset is the maximum weight group) can be formed, and the corresponding coding mode is as follows:
first time slot: RSUc 1 Transmitting coded data packetsRSUc 2 Transmitting coded data packet->Then vehicle v 1 ,v 2 ,v 3 ,v 5 ,v 6 All can obtain the data packet required by oneself through network decoding, because RSUc 1 Transmitting signal and RSUc 2 Transmitting signals at vehicle node v 4 End forming disturbance, vehicle v 4 The data packet required by the user cannot be acquired;
second time slot: RSUc 1 Or RSUc 2 Transmitting data packet a 2 Vehicle v 4 Acquiring a data packet a required by oneself 2 ；
Third time slot: RSUc 1 Or RSUc 2 Transmitting data packet a 3 Vehicle v 4 Acquiring a data packet a required by oneself 3 ；
The following will describe the IDNC encoding scheme of this patent:
nodes in non-intersecting overlay locations update node weights according to a weight-based IDNC graph. Node n in IDNC diagram corresponding to non-cross coverage position vehicle node 113 ，n 121 ，n 131 ，n 254 ，n 265 ，
The calculation formula of the node weight is utilized: node n ijk The weight is w ijk ＝x ij ·|ψ j I, the corresponding node weight w can be calculated’ 113 ＝w’ 121 ＝w’ 131 ＝2，w’ 254 ＝w’ 265 ＝1；RSUc 1 Node n in IDNC graph (i.e., IDNC coding relationship graph) corresponding to vehicle node in coverage area 113 ，n 121 ，n 131 Interference connection edges are not existed between the two, and an independent coding node subset (namely an independent maximum weight group) can be formed; RSUc is similarly provided 2 Node n in IDNC diagram corresponding to vehicle node in coverage area 254 ，n 265 Independent subsets of encoding nodes may be formed.
And sequentially selecting the nodes with the largest weights in the cross coverage positions, and classifying the nodes into the node subset selected by the non-cross positions. Due to node n 143 And node n 113 ，n 121 ，n 131 No IDNC interference connection edge exists, and the node can be classified into n 113 ，n 121 ，n 131 A subset of the nodes that are formed; similarly, node n may be 242 Classification into n 254 And n 265 And the node subsets are formed.
The corresponding IDNC diagram is shown in fig. 4.
Each RSU selects a node subset with the greatest weight for IDNC coding, and deletes the nodes participating in the coding from the IDNC diagram.
Based on the method, the selected node subsets are sequentially n 113 ，n 121 ，n 131 ，n 143 Composed node subset and n 242 ，n 254 ，n 265 And the node subset is composed. The corresponding IDNC network coding mode is as follows:
first time slot: RSUc 1 Transmitting coded data packetsVehicle node v 1 ,v 2 ,v 3 All can obtain the data packet required by the user through network decoding, and the vehicle node v 4 Can obtain the required data packet a through network decoding 3 ；
Second time slot: RSUc 2 Transmitting coded data packetsThen vehicle node v 5 ,v 6 All can obtain the data packet required by the user through network decoding, and the vehicle node v 4 Can obtain the required data packet a through network decoding 2 。
Therefore, according to the weight-based IDNC coding mode, only two time slots are needed to complete data transmission, and fewer time slots can be used to complete data packet transmission.
The application provides an instantaneous decoding network coding method based on the Internet of vehicles, which constructs an IDNC graph based on node weights and interference weights, and according to the graph, an IDNC coding mode is selected at an RSU end, so that the network data throughput can be correspondingly improved, and the network decoding time delay of a data packet can be reduced.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The embodiments of the present application have been described above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present application and the scope of the claims, which are all within the protection of the present application.

Claims (8)

1. An IDNC network coding method based on an Internet of vehicles model is characterized by comprising the following steps:
estimating the probability that each vehicle node in the coverage area of a transmitting signal of each RSU is in different coverage areas at the position of the next data packet transmitting time slot; each RSU constructs an IDNC coding relation diagram corresponding to the RSU according to the probability that the positions of the vehicle nodes are in different coverage areas, the data packet information which the vehicle nodes need to receive and the IDNC network coding conditions;
constructing a maximum weight group by each RSU based on data packet information required to be received by all vehicle nodes in the coverage area of the signal transmitted by each RSU and an IDNC coding relation diagram;
step (3): each RSU carries out IDNC coding according to the data packet corresponding to the node in the maximum weight group, and the node which participates in the coding is deleted from the IDNC coding relation diagram;
step (4): if the node set in the IDNC coding relation diagram is a non-empty subset, the step (1) is switched to iterative operation until the node set in the IDNC coding relation diagram is empty;
the method for constructing the IDNC coding relation diagram corresponding to each RSU specifically comprises the following steps:
determining a node, an IDNC interference edge and a transmitting signal interference edge; if the vehicle node v j From RSUc i Receiving data packet a k With vehicle node v j' From RSUc i Receiving data packet a k' If the IDNC coding condition is not satisfied, node n ijk And node n ij'k' IDNC interference edges exist between the two; vehicle node v j Fall to RSUc i With RSUc i' Cross coverage area, node n ijk And node n i'jk' A transmitting signal interference side exists between the two; vehicle node v j Fall to RSUc i With RSUc i' Cross coverage area, vehicle node v j' Fall on RSUc only i' Within the coverage area, node n ijk And node n i'j'k' A transmitting signal interference side exists between the two; vehicle node v j With vehicle node v j' All fall on RSUc i With RSUc i' Cross coverage area, node n ijk And node n i'j'k' Between which there are transmitting signal interference edges, node n i'jk And node n ij'k' A transmitting signal interference side exists between the two; wherein node n ijk Indicating that it falls on RSUc i Vehicle node v within coverage area j The data packet a needs to be received k Node n ij'k' Indicating that it falls on RSUc i Vehicle node v within coverage area j' The data packet a needs to be received k' ；n i'jk' Indicating that it falls on RSUc i' Vehicle node v within coverage area j The data packet a needs to be received k' The method comprises the steps of carrying out a first treatment on the surface of the Node n i'jk Indicating that it falls on RSUc i' Vehicle node v within coverage area j The data packet a needs to be received k Node n i'j'k' Indicating that it falls on RSUc i' Vehicle node v within coverage area j' The data packet a needs to be received k' ；
The step (2) comprises:
step 201: each RSU constructs a corresponding maximum weight group based on data packet information which is only required to be received by a vehicle node covered by an own transmitting signal in an IDNC coding relation diagram;
step 202: based on the data packet information which is required to be received by all vehicle nodes corresponding to all vehicles in the cross coverage area of the self-transmitted signal and other RSU transmitted signals in the IDNC coding relation diagram, each RSU sequentially selects the node with the largest node weight in each cross coverage area, and classifies the node into the largest weight group corresponding to each RSU.
2. The IDNC network coding method based on the internet of vehicles model of claim 1, wherein the specific method of step 201 comprises:
by RSUc i The IDNC coding relation diagram corresponding to the data packet required to be received by the covered vehicle node is G, and G is taken s ＝G，Representing a certain RSUc i Selecting a maximum weight group from the corresponding IDNC graph;
iterative operation: updating node weight and taking the node with the maximum weightUpdate->
Node is connected withFrom G s Delete and will be associated with node->Node n with connecting edges i'j'k' Has a deletion probability of alpha ijk,i'j'k' The method comprises the steps of carrying out a first treatment on the surface of the If it isContinuing the iterative operation, wherein α ijk,i'j'k' Representing node n ijk And node n ij'k' inter-IDNC interference edge weight, node n according to IDNC coding condition ijk And node n ij'k' With connecting edges between them, alpha ijk,i'j'k' =1, otherwise α ijk,i'j'k' ＝0。
3. The IDNC network coding method based on the internet of vehicles model according to claim 2, wherein the vehicle node v is j Fall on only one RSUc i The product of the probability in coverage and the number of packets that the vehicle node needs to receive is taken as n ijk Node weight of (2), node n ijk The node weights of (a) are expressed as: w (w) ijk ＝x ij ·|ψ j |；x ij Representing vehicle node v j Fall on only one RSUc i Probability in coverage, |ψ j I represents the vehicle node v j The number of packets required to be received.
4. The IDNC network coding method according to claim 1, wherein each RSU estimates a next packet transmission slot vehicle node v based on the current position of each vehicle node in the coverage area of its transmission signal and the vehicle traveling speed j Fall on only one RSUc i Probability x within coverage ij The expression is as follows:
wherein RSUc i The coordinate position in the plane isVehicle node v j The coordinate position of (b) x ,b y ) The running speed is(ε x ,ε y )，R i Representing RSUc i The radius of the communication range area which can be covered, t represents the length of the transmission time slot of the data packet.
5. The IDNC network coding method based on the internet of vehicles model of claim 2, wherein the formula of updating the node weight is expressed as:
wherein alpha is ijk,i'j'k' Representing node n ijk And node n i'j'k' inter-IDNC interference edge weight, node n ijk Indicating that it falls on RSUc i Vehicle node v within coverage area j The data packet a needs to be received k Node n i'j'k' Indicating that it falls on RSUc i' Vehicle node v within coverage area j' The data packet a needs to be received k' ，w ijk Representing node n ijk Weight, w' ijk Representing node n ijk Updated weights, w i'j'k' Representing node n i'j'k' Node weight of (2), node n ijk And node n i'j'k' With connecting edges between them, alpha ijk,i'j'k' =1, otherwise α ijk,i'j'k' ＝0。
6. The IDNC network coding method based on the internet of vehicles model of claim 1, wherein the specific method of step 202 is:
determining node weights of nodes in the cross coverage positions;
if all nodes in the maximum weight group corresponding to the node weight and the RSU covering the node in the cross coverage area do not have IDNC interference connection edges or transmitting signal interference connection edges, the node can be classified into the maximum weight group corresponding to the RSU;
if the node with the greatest weight in the intersection location cannot be categorized into the largest weight group in any RSU covering it, that node constitutes an independent weight maximum group.
7. The IDNC network coding method based on the internet of vehicles model of claim 6, wherein the weight of the node in the cross coverage position is expressed as w ii'jk ＝y ii'j ·|ψ j I, wherein w ii'jk Representing node n ii'jk Weight of node n ii'jk Indicating that it falls on RSUc i With RSUc i' Vehicle node v in cross coverage j The data packet a needs to be received k ，y ii'j Representing vehicle node v j Fall to RSUc i With RSUc i' Probability in cross coverage, |ψ j I represents the vehicle node v j The number of data packets required.
8. The internet of vehicles model-based IDNC network coding method of claim 7, wherein y ii'j Representing vehicle node v j Fall to RSUc i With RSUc i' Probability in cross coverage, expressed as follows:wherein RSUc i' The coordinate position in the plane is +.>R i' Representation->Radius of communication range area that can be covered.
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