CN106603658B - Internet of vehicles data transmission method and device based on software defined network - Google Patents
Internet of vehicles data transmission method and device based on software defined network Download PDFInfo
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- CN106603658B CN106603658B CN201611143296.8A CN201611143296A CN106603658B CN 106603658 B CN106603658 B CN 106603658B CN 201611143296 A CN201611143296 A CN 201611143296A CN 106603658 B CN106603658 B CN 106603658B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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Abstract
The invention provides a software definition-based data transmission method and device for an internet of vehicles, wherein the internet of vehicles comprises an application layer, a control layer and a data forwarding layer; the control layer carries out information interaction with the application layer and the data forwarding layer through the northbound interface and the southbound interface respectively; the method comprises the following steps: the control layer equipment acquires the position information and the future track information of all the data forwarding layer equipment; and when the control layer equipment learns that the data forwarding layer equipment needs to send the data message, the control layer equipment judges whether the data message needs to be transmitted through the long-distance cellular wireless communication network, if so, the control layer equipment instructs the data forwarding layer equipment to forward the data message from the cellular interface, otherwise, a flow table corresponding to the data message is generated according to the position information and the future track information of the data forwarding layer equipment and is issued to the data forwarding layer equipment, so that the data forwarding layer equipment forwards the data message based on the flow table, and the short-distance wireless communication of the data message is realized.
Description
Technical Field
The invention relates to the technical field of wireless communication, in particular to a software defined network-based data transmission method and device for Internet of vehicles.
Background
In recent years, the internet of vehicles technology is considered as one of important technical means for improving vehicle driving safety, improving traffic operation efficiency, reducing traffic energy consumption and reducing traffic pollution, and is receiving increasing attention. In addition, the vehicle is used as an internet entrance, and more information and entertainment services are provided for users in the running vehicle through the internet of vehicles; or the vehicle is used as a sensing node to sense, collect and transmit various data of the urban environment and the vehicle, and the like, and the sensing node is increasingly becoming a new application requirement concerned by people.
Currently widely accepted mainstream internet of vehicles network architectures can be broadly divided into two main categories: the vehicle networking based on the cellular architecture and the vehicle networking based on the short-distance wireless communication technology (such as Wi-Fi, 802.11p, DSRC and the like), wherein the latter is mainly represented by a vehicle ad-hoc network (VANET for short).
The cellular architecture based car networking does not exist as an independent network architecture: the vehicle is used as a type of node in a cellular network, and network access capability is obtained through cellular access. A new generation of cellular network architecture (such as 4G and 5G) adjusts and adapts communication, network protocols and parameters such as air interface protocols of the cellular network architecture according to the particularity of vehicle nodes and the technical requirements of related applications, so that the cellular network can meet the requirements of vehicle node coverage and support various applications such as vehicle driving safety, information entertainment and the like. In a cellular network, when any vehicle needs to send a data packet, it must be sent to the cellular base station via the cellular uplink, and similarly, all downlink data packets are sent to the vehicle via the cellular downlink.
In contrast, a vehicle networking based on short-range wireless communication technology is an ad-hoc network independent of the cellular network, connected to each other by vehicle nodes through short-range wireless communication means, and relying on each vehicle's own routing. In this type of network, long-distance transmission of data packets often has to be done by means of multihop relay, i.e.: the end-to-end path is composed of temporary links formed by meeting of a plurality of vehicles, and data packets can be transmitted from the source node vehicle to the destination node vehicle only through multiple relay transmission among the vehicles.
It can be seen that the cellular architecture internet of vehicles can well support the requirements of relevant applications such as vehicle safety on the real-time performance and reliability of data transmission. The multi-hop transmission mode in the short-distance wireless communication technology car networking architecture brings larger delay and packet loss probability in the data transmission process.
However, with the advent of the big data era, the device operation data of the vehicle itself and the environment, business and other related data in different areas through which the vehicle passes during the driving process are considered to have great application potential and value. Especially, the sensing and collecting means of these data are becoming more and more mature at present, so that the requirement for the transmission and collection of such mass data is becoming an important consideration for the construction of urban networks. From this angle, the characteristics such as free, flexibility, freedom that car networking based on short-range wireless communication technique has make it can occupy a place in the massive data acquisition scene, and its reason is: firstly, the characteristic of free can save huge flow and expense expenses for each user in mass data transmission; secondly, a multi-hop transmission technology is used for transmitting mass non-delay sensitive data, so that the pressure of a cellular network can be greatly relieved, and network resources such as bandwidth and the like are greatly saved for driving safety application; finally, vehicle network access based on short-range wireless communication technology can be accomplished by vehicle enterprises using existing sophisticated technologies (e.g., 802.11p and Wi-Fi), and the generated and transmitted data can also be reasonably confidential through a specific collection manner without having to transmit large amounts of confidential data with high commercial value or related to driving safety through a public operator network. The characteristic has stronger attraction to vehicle production enterprises, especially enterprises with stronger market dominance, thereby increasing the application space of the short-distance access technology.
In summary, if different network transmission means can be efficiently coordinated and applied under the same network architecture, for example, on the basis of strong real-time applications such as ensuring traffic safety by using a cellular network, the transmission of delay insensitive data can be shared by fully utilizing network transmission means such as multi-hop transmission by using short-distance peer-to-peer communication as means, so that the transmission pressure brought by mass data transmission to the cellular network can be effectively shared, and the method has strong practical value and practical significance.
Disclosure of Invention
In view of this, the present invention provides a method and an apparatus for implementing car networking based on a software defined network, which can implement management of multiple network transmission means in a car networking environment and enable the management to meet application requirements of mass data acquisition.
In order to achieve the purpose, the invention provides the following technical scheme:
a data transmission method of the Internet of vehicles based on software definition, the Internet of vehicles comprises an application layer, a control layer and a data forwarding layer; the control layer carries out information interaction with the application layer and the data forwarding layer through the northbound interface and the southbound interface respectively; the method comprises the following steps:
the control layer equipment acquires the position information and the future track information of all the data forwarding layer equipment;
and when the control layer equipment learns that the data forwarding layer equipment needs to send the data message, the control layer equipment judges whether the data message needs to be transmitted through the long-distance cellular wireless communication network, if so, the control layer equipment instructs the data forwarding layer equipment to forward the data message from the cellular interface, otherwise, a flow table corresponding to the data message is generated according to the position information and the future track information of the data forwarding layer equipment and is issued to the data forwarding layer equipment, so that the data forwarding layer equipment forwards the data message based on the flow table, and the short-distance wireless communication of the data message is realized.
A data transmission device of the car networking based on software definition, the car networking comprises an application layer, a control layer and a data forwarding layer; the control layer carries out information interaction with the application layer and the data forwarding layer through the northbound interface and the southbound interface respectively; the device is applied to control layer equipment and comprises:
the acquisition unit is used for acquiring the position information and the future track information of all the data forwarding layer devices;
and the decision unit is used for judging whether the data message needs to be transmitted through the long-distance cellular wireless communication network or not when the data message needs to be transmitted by the data forwarding layer equipment, if so, indicating the data forwarding layer equipment to forward the data message from the cellular interface, otherwise, generating a flow table corresponding to the data message according to the position information and the future track information of the data forwarding layer equipment and issuing the flow table to the data forwarding layer equipment so that the data forwarding layer equipment forwards the data message based on the flow table, and realizing the short-distance wireless communication of the data message.
According to the technical scheme, in the car networking architecture based on the software defined network, when the control layer equipment knows that the data forwarding layer equipment needs to send the data message, the control layer equipment decides the network for transmitting the data message, when the data message needs to be transmitted through the long-distance cellular wireless communication network, the control layer equipment instructs the data forwarding layer equipment to forward the data message from the cellular interface, and when the data message needs to be transmitted through the short-distance wireless communication network, the control layer equipment generates the flow table corresponding to the data message according to the position information and the future track information of the data forwarding layer equipment and sends the flow table to the data forwarding layer equipment, so that the data forwarding layer equipment forwards the data message based on the flow table, and short-distance wireless communication of the data message is.
Drawings
FIG. 1 is a schematic diagram of a software defined networking based vehicle networking architecture according to an embodiment of the present invention;
FIG. 2 is a flowchart of a vehicle network data transmission method based on a software defined network according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a vehicle networking data transmission device based on software definition according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are described in detail below with reference to the accompanying drawings according to embodiments.
In the invention, the implementation idea of the software defined network is applied to the Internet of vehicles to realize the Internet of vehicles architecture based on the software defined network. The vehicle network architecture based on the software defined network, as shown in fig. 1, includes three layers, an application layer, a control layer, and a data forwarding layer, wherein,
an application layer:
various types of service applications in the Internet of vehicles are provided, such as traffic flow monitoring, network condition monitoring, acquisition of various sensing data and elements in a sensing application scene, protocol management of a user and the like. Compared with other software defined network architectures, the application layer in the vehicle networking architecture provided by the invention is characterized in that various application modes in the vehicle networking environment are provided, and the normal application of the modes can be ensured by means of the design of other hierarchical structures.
A control layer:
the control layer is composed of control layer devices, and the number of the control layer devices is determined according to the network scale and the specific organizational structure to be adopted, and can be one or a plurality. In the car networking architecture provided by the invention, when more than one control layer device exists, a hierarchical structure can be adopted, namely, one main control layer device exists to coordinate and manage the next control layer device, and the hierarchical structure supports two or more levels. The control layer device performs centralized control on the forwarding behavior and policy of the network data, including but not limited to the following control functions: network flow control, routing control, scheduling control, policy management, and the like; each control module may support the replacement of algorithms, protocols, policies, etc., i.e., support software definitions. The control layer device manages and controls the network by grasping the global information, and makes decisions on resource scheduling, routing, and the like.
The global information that the control layer device can grasp includes but is not limited to: location information (indicating the current location of the data forwarding layer device, which may be expressed in terms of longitude and latitude, uploaded by the data forwarding layer device itself or acquired by a traffic authority through monitoring means) and trajectory information (including past trajectory information and future trajectory information) of the data forwarding layer device.
Since the control layer device can adopt a global view to make a scheduling decision, the routing and scheduling accuracy (i.e. the probability of ensuring that a data packet can be delivered without being lost) is necessarily much higher than that of a VANET that makes a distributed routing decision only based on local information or even only on information of a single node.
A data forwarding layer:
the data forwarding layer is composed of data forwarding layer devices. There are two types of data forwarding layer devices: the system comprises vehicle nodes and roadside devices (Road-Side Unit, RSU, a device which is built by depending on urban roads and the like, has a wireless communication function, can be used for collecting vehicle networking data, and is a known term in the vehicle networking related research field). The positions of the vehicle nodes are not fixed, the future track information of the vehicle nodes indicates the track to be traveled and is represented by information including a travel road section, a travel direction, a travel speed and the like; the future track information of the vehicle node can be acquired based on means such as uploading of a vehicle-mounted navigator, and the information is not acquired when a user does not allow the uploading. The roadside apparatus is fixed in position, and its future trajectory information is empty.
Because the internet of vehicles has a large network scale, network clustering (also called zoning and the like) management can be implemented on the data forwarding layer equipment, and the condition of no clustering can be regarded as that only one cluster exists in the network. Network clustering may be according to a variety of clustering logic: the division can be performed according to the geographical location area, for example, a city can be divided into 10 × 10 km grids, vehicles in each grid are grouped into a cluster, and corresponding control layer equipment is allocated for management; or may be divided according to the functional attributes of the data forwarding layer devices, for example, all 9 buses in a city may be divided into one cluster, or all taxis of a certain company may be divided into one cluster, and corresponding control layer devices are allocated for management. The management mode of network clustering can reduce the management burden of each control layer device and improve the response speed of each control layer device, and meanwhile, the network resources can be more accurately mastered. When different clusters adopt different control layer devices for management, the different clusters need to be finally managed by one global control layer device, so that the global synchronization of partial information is ensured, and the cross-region switching of vehicle nodes in the data forwarding layer device is coordinated.
In the invention, the control layer carries out information interaction with the application layer through the northbound interface and carries out information interaction with the data forwarding layer through the southbound interface (SBI), and the SBI is responsible for transmitting control and notification messages. The data transmission between the data forwarding layer devices adopts a short-distance wireless communication network to realize peer-to-peer and multi-hop transmission.
In conjunction with the above description of the network architecture of the present invention, the following describes the most critical interface protocol in the software defined architecture, i.e., the southbound interface protocol.
In the embodiment of the present invention, the OpenFlow protocol widely used at present is extended to serve as a southbound interface protocol of the network architecture of the present invention, and an improved version is hereinafter referred to as V-OpenFlow.
In the embodiment of the invention, the southbound interface protocol defines a port (namely a wireless interface), a flow table, a communication channel and a communication flow of a data forwarding layer, and the protocol flow needs 30 message types in total and is used for realizing the functions of communication channel establishment, channel maintenance, port characteristic acquisition, exception packet reporting, flow table issuing, flow table deletion and the like. Most messages still adopt the message types defined by the OpenFlow protocol, and only the changed message types are described below.
Multipart reply message:
when the network is initialized, the control layer device performs network initialization through initialization control signaling and the like and obtains node information, wherein the node information is obtained through interaction of 'Multipart request/reply message'. The OpenFlow protocol uses a "Multipart request/reply message" to obtain port information of a data plane node. And the V-OpenFlow uses the identifier field to extend the V-OpenFlow, so as to describe the port information, the state information, and the like of the data forwarding layer device.
Wherein the Multipart request message does not need to be extended; the "Multipart reply message" is sent by the data forwarding layer device, and it should carry the port information and the status information of the data forwarding layer device, so the "Multipart reply message" is extended by using the ofp _ identifier _ structure, and the structure is as follows:
struct ofp_experimenter_structure{
uint32_t experimenter；
uint32_t exp_type；
uint8_t experimenter_data[0]；
}；
wherein, the identifier field is ID of the message;
the exp _ type field identifies the type of structure, which can be identified by a preset string;
the identifier _ data [0] is an extensible content field, and information such as a position, a driving speed, a cache capacity and the like is added to the field, and as a preferred implementation mode, the name and the structure of the identifier _ data [0] can be implemented as follows:
struct ofp_port_desc_prop_vehicle{
uint16_t type；
uint16_t length；
uint8_t moving_speed；
uint8_t caching_capacity；
unit8_t pad[2]；
struct location；
}；
wherein, type is OFPPDPT _ extension, which means that the structure is an extension message;
length represents the length of the structure;
moving _ speed represents the current vehicle speed;
the caching _ capacity represents the residual cache capacity of the node;
pad [2] is a padding bit;
the location represents the vehicle position and is represented by longitude and latitude, and the specific structure is as follows:
struct location{
uint8_t altitude；
uint8_t longitude；
}
echo request message:
in the OpenFlow protocol, after a control communication channel is established between a control layer device and a data forwarding layer device, the communication channel is maintained through an "Echo request/reply message", and meanwhile, the control of a short-range wireless link is realized by using the information, that is, a command is issued through the "Echo request message" to allow or prohibit the sending of a Hello message.
When the data forwarding layer device has a data message to be sent, firstly, a Packet _ In message is sent to the control layer device, the control layer device determines a next hop node (set) of the data Packet according to address information and the like In a message body, the whole situation of the network is combined, the current determined routing rule is used, and a Flow table decision of the next hop node (set) is issued through a Flow _ Mod message. After the data forwarding layer device obtains the flow table, it knows the next hop node of the data packet and waits for the establishment of the short-distance wireless link. When the node is considered to meet the appointed next hop in the future road section according to the currently adopted judgment rule through the global position information of the node, the control layer equipment issues a command through a link keeping message 'Echo message' to start the sending of a short-distance Hello message (namely authorizing the establishment of a short-distance wireless link); the data forwarding layer equipment can establish a short-distance wireless link with the selected next hop node by using the Hello message and complete the delivery of the data packet.
In V-OpenFlow, an "Echo request message" needs to be extended to implement communication channel maintenance and link establishment command issue, which is introduced as follows:
the Echo request message structure is as follows:
struct ofp_echo{
struct ofp_header；
uint8_t echo_data[0]；
}
as a preferred implementation, the name and structure of echo _ data [0] can be implemented as follows:
struct opportunistic_link_switch{
struct opf_port；
boolean switch；
}
wherein opf _ port represents the ID of the port that allows the establishment of the peer opportunistic link;
the switch represents whether to start sending the Hello message between the nodes of the data forwarding layer, and the value is on or off.
The car networking architecture based on the software defined network and the southbound interface protocol therein of the present application are described in detail above, and the data transmission method of the present invention is implemented based on the architecture, which is described in detail below with reference to fig. 2.
Referring to fig. 2, fig. 2 is a flowchart of a data transmission method in a car networking based on a software defined network according to an embodiment of the present invention, where the car networking includes an application layer, a control layer, and a data forwarding layer; the control layer carries out information interaction with the application layer and the data forwarding layer through the northbound interface and the southbound interface respectively; as shown in fig. 2, the method comprises the steps of:
The data forwarding layer equipment comprises a vehicle node and a roadside device.
The control layer equipment can acquire the position information and the future track information of all vehicle nodes and roadside devices when the vehicle network is initialized. Because the vehicle node is mobile and the position is not fixed, the position information and the future track information of the vehicle node need to be reported to the control layer equipment periodically, so that the control layer equipment can update the position information and the future track information of the vehicle node in time, and the global information can be mastered accurately.
When the data forwarding layer device generates a data message of a data flow or receives a data message of a data flow and needs to forward, the data forwarding layer device sends an RTS (Ready to Send) message to the control layer device, and the control layer device receives the RTS message and determines/learns that the data forwarding layer device needs to Send the data message. The RTS message corresponds to the Packet _ In message described above.
In practical application, the data message cannot be forwarded without limit, so that the forwarding hop count is limited. In this embodiment, the short-range wireless communication network (i.e. the network using the short-range wireless technology) is preferentially used to transmit the data packet, that is, the short-range wireless technology is used to perform peer-to-peer and multi-hop transmission of the data packet between the data forwarding layer devices. However, if the data packet has been forwarded for multiple times and still fails to reach the target device (the target device in the present invention is a roadside device, and the roadside device can transmit the data packet back to the server via a wired or wireless network), it is necessary to consider abandoning the short-range wireless communication network to transmit the data packet, and then choose to use the long-range cellular wireless communication network (i.e. cellular network) to transmit the data packet.
Therefore, in the invention, a maximum forwarding hop count is preset, and a field carrying the transmission hop count (namely the forwarded hop count/times) of the data message is set in the RTS message. After the control layer device receives the RTS message sent by the data forwarding layer device, a subsequent forwarding control action can be determined according to a comparison result between the transmission hop count of the data message carried in the RTS message and the preset maximum forwarding hop count, specifically, if the transmission hop count of the data message carried in the RTS message is greater than the preset maximum forwarding hop count, it can be determined that the data message needs to be transmitted through the long-distance cellular wireless communication network, otherwise, it can be determined that the data message continues to be transmitted through the short-distance wireless communication network.
When the data message needs to be transmitted through the long-distance cellular wireless communication network, the control layer equipment informs the data forwarding layer equipment to send the data message out through the cellular interface. When data messages need to be transmitted through the short-distance wireless communication network, the control layer device firstly generates a flow table corresponding to the data messages according to the position information and the future track information of the data forwarding layer device, and issues the flow table to the data forwarding layer device, so that the data forwarding layer device forwards the data messages based on the flow table. Wherein the flow table includes one or more next hop information therein.
The short-distance wireless communication is applied between the devices with close distances, in the invention, the current data forwarding layer device realizes the short-distance wireless communication by sending the data message to other nearby data forwarding layer devices, therefore, other data forwarding layer devices with close distances to the current data forwarding layer device can be used as the next hop of the data message. However, since the location information of the vehicle nodes in the data forwarding layer devices changes with the change of the future trajectory, the data forwarding layer devices with close distances may gradually get closer, and the data forwarding layer devices with far distances may gradually get closer. Therefore, when determining the next hop of the data packet, the location information and the future trajectory information of the data forwarding layer device need to be considered, and only other data forwarding layer devices which are closer to the current data forwarding layer device and are in a shortening trend in the future are suitable for being used as the next hop of the data packet.
In this embodiment, the method for generating the flow table corresponding to the data packet according to the position information and the future trajectory information of the data forwarding layer device may specifically be: determining a first data forwarding layer device set with the distance to the data forwarding layer device within a preset distance range according to the position information of the data forwarding layer device; determining a second data forwarding layer equipment set with a shortening trend of the distance between the second data forwarding layer equipment and the data forwarding layer equipment based on the future track information of the data forwarding layer equipment; and calculating the intersection of the first data forwarding layer equipment set and the second data forwarding layer equipment set, and writing all the data forwarding layer equipment information in the intersection operation result into a flow table corresponding to the data message as next-hop information.
It should be noted that the above is only one specific method for generating the flow table, and actually, other implementation methods may also be used, as long as it is ensured that the next hop in the flow table is closer to the current data forwarding layer device and the distance from the current data forwarding layer device is in a decreasing trend.
In the present invention, data forwarding between data forwarding layer devices depends on a short-range wireless communication technology, before communication, a wireless link between data forwarding layer devices needs to be established first, and the establishment process of the wireless link between the data forwarding layer devices is significantly different from the establishment process of the wireless link in any other architecture:
in the car networking environment, the establishment of wireless links between nodes (in the present invention, data forwarding layer devices) under other network architectures is divided into two categories: pure certainty and pure opportunity; wherein the content of the first and second substances,
the pure certainty means that the control layer device authorizes the two nodes to establish a communication link when knowing that the positions of the two nodes are within the communication radius of each other by means of the GPS information by means of mastering the positions of the nodes in the global information, and at the moment, the two nodes can initiate a link establishment process or directly broadcast and send a data packet;
the pure opportunity means that under the condition of no global information, the Hello message is continuously broadcasted among vehicles, and a link is established with a node which can receive and feed back the Hello message.
The drawbacks of the above two are very obvious: the former is centralized control, and needs to acquire real-time information such as GPS and perform global computation very frequently by control layer equipment, and such behavior needs a lot of overhead, and at the same time, has the following problems: 1) it is impossible to use in large-scale networks; 2) the loss or delay of some frames will cause the loss of transmission efficiency, and the frame loss and delay are very common. In contrast, although the disadvantage of centralized control is avoided in the latter completely distributed control, such a setup process requires massive HELLO message broadcasting, which easily causes resource waste, and in an area with tight communication opportunities, such as an intersection or other dense area of vehicles, the resource is unreasonably used due to collision of HELLO messages, channel contention, and the like.
Firstly, control layer equipment is required to master position information of data forwarding layer equipment, vehicle nodes in the data forwarding layer equipment are required to report the position information of the control layer equipment periodically (the time length of one period is T), the value of T can be determined according to network scale and the like and can be far larger than the reporting interval required in a pure certainty method; secondly, the data forwarding layer device does not continuously broadcast the Hello message, but starts to send the Hello message when receiving the authorization of the control layer device, and establishes wireless connection with the next hop node in the flow table.
The specific connection authorization process of the control layer device is as follows: the control layer device first generates a flow table corresponding to the data packet according to the position information and the future track information of the data forwarding layer device, and then judges whether a connection authorization condition is met between the data forwarding layer device and each next hop in the flow table (authorization is realized by using Echo request message), if the connection authorization condition is met, the data forwarding layer device is authorized to establish a connection with the next hop, so that the data forwarding layer device starts to execute the operation data forwarding layer device for establishing the connection with the next hop after receiving the authorization of the control layer device.
Wherein the content of the first and second substances,
after the control layer device generates a flow table corresponding to the data packet, the method for judging whether the connection authorization condition is met between the data forwarding layer device and each next hop in the flow table is as follows: if the next hop is the roadside device, determining that the data forwarding layer equipment and the roadside device accord with a connection authorization condition; if the data forwarding layer equipment and the next hop are located on the same driving road section and the driving directions of the data forwarding layer equipment are opposite, determining that the data forwarding layer equipment and the next hop meet the connection authorization condition; otherwise, determining that the data forwarding layer equipment does not accord with the connection authorization condition with the next hop, wherein the same driving road section refers to a road section for vehicles to drive away only at two intersections.
After receiving the authorization of the control layer device to the connection between the data forwarding layer device and a certain next hop, the data forwarding layer device starts to execute the operation of establishing the connection between the data forwarding layer device and the certain next hop, and the specific method is as follows: and broadcasting the Hello message outwards, and establishing connection with the next hop after receiving a response message returned by the next hop. And after the connection with the next hop is established, stopping broadcasting the Hello message outwards until receiving the connection authorization between the data forwarding layer equipment and other next hops.
In this embodiment, after the control layer device generates a flow table corresponding to the data packet and issues the flow table to the data forwarding layer device, the data forwarding layer device may forward the data packet based on the flow table, and since the roadside device is a target device of the data packet, if the roadside device exists in the next hop, the packet is preferentially sent to the roadside device, and therefore, the specific forwarding method is as follows: and determining all next hops which have established connection with the data forwarding layer equipment, if one next hop exists as a roadside device, forwarding the data message to the next hop through the established connection with the next hop, otherwise, selecting one next hop from the next hop, and forwarding the data message to the next hop through the established connection with the next hop.
In this embodiment, since the roadside apparatus is a target device of the data packet, once the roadside apparatus receives the data packet, it is not necessary to continue transmitting the data packet in the network, and for this reason, a field carrying data packet information is set in the RTS packet, where the data packet information can represent the data packet. When the data forwarding layer equipment receives the data message sent by other data forwarding layer equipment, if the data forwarding layer equipment is a roadside device, the received data message is reported to the control layer equipment, at this time, the control layer equipment can set a rule for discarding the data message, and when an RTS message carrying the data message information is received again, the data forwarding layer equipment sending the RTS message is informed to discard the data message according to the rule for discarding the data message, so that the data message cannot be continuously transmitted in the network.
The invention also provides a vehicle networking data transmission device based on software definition, which is described in detail with reference to fig. 3.
Referring to fig. 3, fig. 3 is a schematic structural diagram of a data transmission device in a car networking based on software definition according to an embodiment of the present invention, where the car networking includes an application layer, a control layer, and a data forwarding layer; the control layer carries out information interaction with the application layer and the data forwarding layer through the northbound interface and the southbound interface respectively; the device is applied to control layer equipment and comprises:
an obtaining unit 301, configured to obtain location information and future trajectory information of all data forwarding layer devices;
a decision unit 302, configured to determine whether data packets need to be transmitted through a long-distance cellular wireless communication network when it is known that a data forwarding layer device needs to send data packets, if so, instruct the data forwarding layer device to forward the data packets from a cellular interface, otherwise, generate a flow table corresponding to the data packets according to the position information and future trajectory information of the data forwarding layer device and send the flow table to the data forwarding layer device, so that the data forwarding layer device forwards the data packets based on the flow table, and implement short-distance wireless communication of the data packets.
In the device shown in figure 3 of the drawings,
the data forwarding layer equipment comprises vehicle nodes and roadside devices;
the obtaining unit 301 is configured to obtain position information and future track information of all vehicle nodes and roadside devices when the internet of vehicles is initialized, and update the position information and the future track information of each vehicle node according to the position information and the future track information periodically reported by each vehicle node.
In the device shown in figure 3 of the drawings,
the decision unit 302, when receiving an RTS message ready to be sent from a data forwarding layer device, learns that the data forwarding layer device needs to send a data message;
after receiving the RTS message sent by the data forwarding layer device, the decision unit 302 determines whether the transmission hop count of the data message carried in the RTS message is greater than a preset maximum forwarding hop count, and if so, determines that the data message needs to be transmitted through the long-distance cellular wireless communication network, otherwise, determines that the data message does not need to be transmitted through the long-distance cellular wireless communication network.
In the device shown in figure 3 of the drawings,
the future track information of the vehicle node comprises: a travel section, a travel direction, and a travel speed of the vehicle node; the future trajectory information of the wayside device is null;
the flow table includes next hop information;
the method for generating the flow table corresponding to the data packet according to the position information and the future trajectory information of the data forwarding layer device by the decision unit 302 is as follows: determining a first data forwarding layer device set with the distance to the data forwarding layer device within a preset distance range according to the position information of the data forwarding layer device; determining a second data forwarding layer equipment set with a shortening trend of the distance between the second data forwarding layer equipment and the data forwarding layer equipment based on the future track information of the data forwarding layer equipment; and calculating the intersection of the first data forwarding layer equipment set and the second data forwarding layer equipment set, and writing all the data forwarding layer equipment information in the intersection operation result into a flow table corresponding to the data message as next-hop information.
In the device shown in figure 3 of the drawings,
the decision unit 302, after generating a flow table corresponding to the data packet of the data forwarding layer device, is further configured to: and judging whether the connection authorization condition is met between the data forwarding layer equipment and each next hop in the flow table, if so, authorizing the data forwarding layer equipment to establish the connection with the next hop so as to enable the data forwarding layer equipment to execute the operation of establishing the connection with the next hop.
In the device shown in figure 3 of the drawings,
the decision unit 302, when determining whether the connection authorization condition is met between the data forwarding layer device and each next hop in the flow table, is configured to: if the next hop is the roadside device, determining that the data forwarding layer equipment and the roadside device accord with a connection authorization condition; if the data forwarding layer equipment and the next hop are located on the same driving road section and the driving directions of the data forwarding layer equipment are opposite, determining that the data forwarding layer equipment and the next hop meet the connection authorization condition; otherwise, determining that the data forwarding layer equipment does not accord with the connection authorization condition with the next hop, wherein the same driving road section refers to a road section for vehicles to drive away only at two intersections.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (12)
1. The software definition-based data transmission method of the Internet of vehicles is characterized in that the Internet of vehicles comprises an application layer, a control layer and a data forwarding layer; the control layer carries out information interaction with the application layer and the data forwarding layer through the northbound interface and the southbound interface respectively; the method comprises the following steps:
the control layer equipment acquires the position information and the future track information of all the data forwarding layer equipment;
when the control layer equipment learns that the data forwarding layer equipment needs to send the data message, the control layer equipment judges whether the data message needs to be transmitted through a long-distance cellular wireless communication network, if so, the control layer equipment instructs the data forwarding layer equipment to forward the data message from a cellular interface, otherwise, a flow table corresponding to the data message is generated according to the position information and the future track information of the data forwarding layer equipment and is issued to the data forwarding layer equipment, so that the data forwarding layer equipment forwards the data message based on the flow table, and short-distance wireless communication of the data message is realized;
wherein the content of the first and second substances,
when the control layer equipment receives a ready-to-send RTS message sent by the data forwarding layer equipment, the control layer equipment learns that the data forwarding layer equipment needs to send a data message;
after receiving the RTS message sent by the data forwarding layer equipment, the control layer equipment judges whether the transmission hop count of the data message carried in the RTS message is greater than the preset maximum forwarding hop count, if so, the control layer equipment determines that the data message needs to be transmitted through the long-distance cellular wireless communication network, otherwise, the control layer equipment determines that the data message does not need to be transmitted through the long-distance cellular wireless communication network.
2. The method of claim 1,
the data forwarding layer equipment comprises vehicle nodes and roadside devices;
the control layer equipment acquires the position information and the future track information of all vehicle nodes and roadside devices when a vehicle network is initialized, and updates the position information and the future track information of the vehicle nodes according to the position information and the future track information periodically reported by each vehicle node.
3. The method of claim 2,
the future track information of the vehicle node comprises: a travel section, a travel direction, and a travel speed of the vehicle node; the future trajectory information of the wayside device is null;
the flow table includes next hop information;
the method for generating the flow table corresponding to the data message according to the position information and the future track information of the data forwarding layer device comprises the following steps: determining a first data forwarding layer device set with the distance to the data forwarding layer device within a preset distance range according to the position information of the data forwarding layer device; determining a second data forwarding layer equipment set with a shortening trend of the distance between the second data forwarding layer equipment and the data forwarding layer equipment based on the future track information of the data forwarding layer equipment; and calculating the intersection of the first data forwarding layer equipment set and the second data forwarding layer equipment set, and writing all the data forwarding layer equipment information in the intersection operation result into a flow table corresponding to the data message as next-hop information.
4. The method of claim 2,
after the control layer device generates the flow table corresponding to the data packet of the data forwarding layer device, the method further includes: judging whether the connection authorization condition is met between the data forwarding layer equipment and each next hop in the flow table, if the connection authorization condition is met, authorizing the data forwarding layer equipment to establish the connection with the next hop so that the data forwarding layer equipment executes the operation of establishing the connection with the next hop;
the method for forwarding the data message by the data forwarding layer equipment based on the flow table comprises the following steps: and determining all next hops which have established connection with the data forwarding layer equipment, if one next hop exists as a roadside device, forwarding the data message to the next hop through the established connection with the next hop, otherwise, selecting one next hop from the next hop, and forwarding the data message to the next hop through the established connection with the next hop.
5. The method of claim 4,
the method for judging whether the connection authorization condition is met between the data forwarding layer device and each next hop in the flow table is as follows: if the next hop is the roadside device, determining that the data forwarding layer equipment and the roadside device accord with a connection authorization condition; if the data forwarding layer equipment and the next hop are located on the same driving road section and the driving directions of the data forwarding layer equipment are opposite, determining that the data forwarding layer equipment and the next hop meet the connection authorization condition; otherwise, determining that the data forwarding layer equipment does not accord with the connection authorization condition with the next hop, wherein the same driving road section refers to a road section for vehicles to drive away only at two intersections.
6. The method of claim 4,
the method for the data forwarding layer device to establish the connection with the next hop comprises the following steps: and the data forwarding layer equipment broadcasts a Hello message outwards, and establishes connection with the next hop after receiving a response message returned by the next hop.
7. The method of claim 2,
when the data forwarding layer equipment receives data messages sent by other data forwarding layer equipment, if the data forwarding layer equipment is a roadside device, the received data messages are reported to the control layer equipment, so that the control layer equipment sets rules for discarding the data messages, and when RTS messages carrying the data message information are received again, the data forwarding layer equipment sending the RTS messages is informed to discard the data messages according to the rules for discarding the data messages.
8. The software definition-based data transmission device for the Internet of vehicles is characterized in that the Internet of vehicles comprises an application layer, a control layer and a data forwarding layer; the control layer carries out information interaction with the application layer and the data forwarding layer through the northbound interface and the southbound interface respectively; the device is applied to control layer equipment and comprises:
the acquisition unit is used for acquiring the position information and the future track information of all the data forwarding layer devices;
the decision unit is used for judging whether the data message needs to be transmitted through the long-distance cellular wireless communication network when the data message needs to be transmitted by the data forwarding layer equipment, if so, the data forwarding layer equipment is instructed to forward the data message from the cellular interface, otherwise, a flow table corresponding to the data message is generated according to the position information and the future track information of the data forwarding layer equipment and is issued to the data forwarding layer equipment, so that the data forwarding layer equipment forwards the data message based on the flow table, and the short-distance wireless communication of the data message is realized;
wherein the content of the first and second substances,
the decision unit is used for acquiring that the data forwarding layer equipment needs to send the data message when receiving the RTS message to be sent on the data forwarding layer equipment;
the decision unit receives an RTS message sent by the data forwarding layer device, judges whether the transmission hop count of the data message carried in the RTS message is greater than a preset maximum forwarding hop count, if so, determines that the data message needs to be transmitted through the long-distance cellular wireless communication network, otherwise, determines that the data message does not need to be transmitted through the long-distance cellular wireless communication network.
9. The apparatus of claim 8,
the data forwarding layer equipment comprises vehicle nodes and roadside devices;
the acquisition unit is used for acquiring the position information and the future track information of all vehicle nodes and roadside devices when the internet of vehicles is initialized, and updating the position information and the future track information of the vehicle nodes according to the position information and the future track information periodically reported by each vehicle node.
10. The apparatus of claim 9,
the future track information of the vehicle node comprises: a travel section, a travel direction, and a travel speed of the vehicle node; the future trajectory information of the wayside device is null;
the flow table includes next hop information;
the method for the decision unit to generate the flow table corresponding to the data message according to the position information and the future track information of the data forwarding layer device is as follows: determining a first data forwarding layer device set with the distance to the data forwarding layer device within a preset distance range according to the position information of the data forwarding layer device; determining a second data forwarding layer equipment set with a shortening trend of the distance between the second data forwarding layer equipment and the data forwarding layer equipment based on the future track information of the data forwarding layer equipment; and calculating the intersection of the first data forwarding layer equipment set and the second data forwarding layer equipment set, and writing all the data forwarding layer equipment information in the intersection operation result into a flow table corresponding to the data message as next-hop information.
11. The apparatus of claim 9,
the decision unit, after generating the flow table corresponding to the data packet of the data forwarding layer device, is further configured to: and judging whether the connection authorization condition is met between the data forwarding layer equipment and each next hop in the flow table, if so, authorizing the data forwarding layer equipment to establish the connection with the next hop so as to enable the data forwarding layer equipment to execute the operation of establishing the connection with the next hop.
12. The apparatus of claim 11,
the decision unit, when determining whether the connection authorization condition is met between the data forwarding layer device and each next hop in the flow table, is configured to: if the next hop is the roadside device, determining that the data forwarding layer equipment and the roadside device accord with a connection authorization condition; if the data forwarding layer equipment and the next hop are located on the same driving road section and the driving directions of the data forwarding layer equipment are opposite, determining that the data forwarding layer equipment and the next hop meet the connection authorization condition; otherwise, determining that the data forwarding layer equipment does not accord with the connection authorization condition with the next hop, wherein the same driving road section refers to a road section for vehicles to drive away only at two intersections.
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