CN106603658B - Internet of vehicles data transmission method and device based on software defined network - Google Patents

Abstract

The invention provides a software-defined vehicle networking data transmission method and device. The vehicle networking includes an application layer, a control layer and a data forwarding layer; the control layer is connected to the application layer and the data forwarding layer through the northbound interface and the southbound interface respectively performing information exchange; the method includes: the control layer device obtains the location information and future trajectory information of all the data forwarding layer devices; when the control layer device learns that the data forwarding layer device needs to send a data message, judging whether it is necessary to pass the long-distance cellular wireless communication network Transmit data packets, if yes, instruct the data forwarding layer device to forward the data packets from the cellular interface, otherwise, generate a flow table corresponding to the data packets according to the location information and future trajectory information of the data forwarding layer device and send it to the data forwarding layer device, so that the data forwarding layer device forwards the data packet based on the flow table, and realizes the short-distance wireless communication of the data packet.

Description

A method and device for data transmission of Internet of Vehicles based on software-defined network

technical field

The present invention relates to the technical field of wireless communication, in particular to a method and device for data transmission of the Internet of Vehicles based on a software-defined network.

Background technique

In recent years, the Internet of Vehicles technology is considered to be one of the important technical means to improve vehicle driving safety, improve traffic operation efficiency, reduce traffic energy consumption, and reduce traffic pollution, and has received increasing attention. In addition, the vehicle is used as the Internet entrance to provide more information and entertainment services for users in the moving vehicle through the Internet of Vehicles; or the vehicle is used as a sensing node to perceive, collect and transmit various data of the urban environment and the vehicle itself. And so on, it has also increasingly become a new application requirement that attracts attention.

The currently widely accepted mainstream IoV network architectures can be roughly divided into two categories: IoV based on cellular architecture and IoV based on short-range wireless communication technologies (such as Wi-Fi, 802.11p, DSRC, etc.). The main representative is the vehicle ad-hoc network (referred to as VANET).

The Internet of Vehicles based on the cellular architecture does not exist as an independent network system: as a kind of node in the cellular network, the vehicle obtains the network access capability through cellular access. The new-generation cellular network architecture (such as 4G, 5G) adjusts and adapts its own air interface protocol and other communication and network protocols and parameters according to the particularity of vehicle nodes and the technical requirements of related applications, so that the cellular network can meet the requirements of It meets the needs of vehicle node coverage, and supports various applications such as vehicle driving safety and infotainment. 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, the Internet of Vehicles based on short-range wireless communication technology is an ad hoc network independent of the cellular network, in which vehicle nodes are connected to each other through short-range wireless communication, and rely on each vehicle's own route. In this type of network, the long-distance transmission of data packets must often be completed by means of multi-hop relays, that is, the end-to-end path is composed of temporary links formed by several vehicles due to encounters, and data packets must pass through multiple inter-vehicle links. It takes several relay transfers to transmit from the source node vehicle to the destination node vehicle.

It can be seen that the cellular architecture of the Internet of Vehicles can well support the real-time and reliability requirements of data transmission for related applications such as vehicle safety. The multi-hop transmission method in the short-range wireless communication technology vehicle networking architecture will bring greater delay and packet loss probability in the data transmission process.

However, with the advent of the era of big data, the operating data of the vehicle's own equipment and the environment, business and other related data in different areas in the driving process are considered to have huge application potential and value. In particular, the current perception and collection methods for these data are becoming more and more mature, making the demand for such massive data transmission and collection increasingly an important consideration for urban network construction. From this point of view, the free, flexible, and free characteristics of the Internet of Vehicles based on short-range wireless communication technology enable it to occupy a place in massive data collection scenarios. The reasons are: first, its free features can be used in Mass data transmission saves huge traffic and tariff overhead for all users; secondly, the use of multi-hop transmission technology to transmit massive non-delay sensitive data can greatly relieve the pressure on the cellular network, and at the same time greatly save driving safety applications. network resources such as bandwidth; finally, vehicle network access based on short-range wireless communication technology can be completed by vehicle companies using existing mature technologies (such as using 802.11p and Wi-Fi, etc.), and the data generated and transmitted can also be generated and transmitted through specific The collection method is reasonably confidential without necessitating the transmission of large amounts of confidential data of high commercial value or related to driving safety through public operator networks. This feature is attractive to vehicle manufacturers, especially those with a strong market dominance, thus increasing the space for the application of short-distance access technology.

To sum up, if different network transmission methods can be efficiently coordinated and applied under the same network architecture, for example, on the basis of real-time applications such as ensuring traffic safety with cellular networks, short-distance peer-to-peer communication can be fully utilized. It can effectively share the transmission pressure brought by massive data transmission to the cellular network, which has strong practical value and practical significance.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a method and device for realizing the Internet of Vehicles based on a software-defined network, which can realize the management of various network transmission means in the Internet of Vehicles environment and make it meet the application requirements of mass data collection.

In order to achieve the above object, the present invention provides the following technical solutions:

A software-defined Internet of Vehicles data transmission method, the Internet of Vehicles includes an application layer, a control layer and a data forwarding layer; the control layer exchanges information with the application layer and the data forwarding layer through a northbound interface and a southbound interface respectively; the method include:

The control layer device obtains the location information and future trajectory information of all data forwarding layer devices;

When the control layer device learns that the data forwarding layer device needs to send a data packet, it determines whether the data packet needs to be transmitted through the long-distance cellular wireless communication network. If so, it instructs the data forwarding layer device to forward the data packet from the cellular interface, otherwise, according to The location information and future trajectory information of the data forwarding layer device generates a flow table corresponding to the data packet and sends it to the data forwarding layer device, so that the data forwarding layer device forwards the data packet based on the flow table, and realizes the short-range wireless transmission of the data packet. communication.

A software-defined Internet of Vehicles data transmission device, the Internet of Vehicles includes an application layer, a control layer and a data forwarding layer; the control layer exchanges information with the application layer and the data forwarding layer through a northbound interface and a southbound interface respectively; the device Applied to control plane devices, including:

an acquisition unit for acquiring the location information and future trajectory information of all data forwarding layer devices;

The decision-making unit is used to determine whether the data packet needs to be transmitted through the long-distance cellular wireless communication network when the device at the data forwarding layer needs to send a data packet, and if so, instruct the device at the data forwarding layer to forward the data packet from the cellular interface, otherwise , according to the location information and future trajectory information of the data forwarding layer device, generate a flow table corresponding to the data packet and send it to the data forwarding layer device, so that the data forwarding layer device forwards the data packet based on the flow table and realizes the shortening of the data packet. Distance wireless communication.

It can be seen from the above technical solutions that in the present invention, in the IoV architecture based on the software-defined network, when the control layer device learns that the data forwarding layer device needs to send data packets, it decides the network to transmit the data packets, and when it needs to pass the long When transmitting data packets from the cellular wireless communication network, the data forwarding layer device is instructed to forward the data packets from the cellular interface. A flow table corresponding to the data message is generated and sent to the data forwarding layer device, so that the data forwarding layer device forwards the data message based on the flow table, and realizes short-distance wireless communication of the data message.

Description of drawings

1 is a schematic diagram of an Internet of Vehicles architecture based on a software-defined network according to an embodiment of the present invention;

2 is a flowchart of a method for transmitting vehicle network data based on a software-defined network according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a software-defined Internet of Vehicles data transmission device according to an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

In the present invention, the realization idea of the software-defined network is applied to the Internet of Vehicles to realize the architecture of the Internet of Vehicles based on the software-defined network. The vehicle network architecture based on software-defined network, as shown in Figure 1, includes three layers: application layer, control layer, and data forwarding layer.

Application layer:

Provide various types of business applications in the Internet of Vehicles, such as traffic flow monitoring, network condition monitoring, acquisition of various sensing data and elements in sensing application scenarios, and user management of protocols. Compared with other software-defined network architectures, in the Internet of Vehicles architecture proposed by the present invention, the application layer is characterized in that it provides various application modes in the Internet of Vehicles environment, and can rely on the design of other hierarchical structures to ensure the normal application of these modes. .

control layer:

The control layer is composed of control layer devices. The number of control layer devices is determined according to the network scale and the specific organizational structure to be adopted. It can be one or several. In the Internet of Vehicles architecture proposed by the present invention, when there is more than one control layer device, a hierarchical structure can be adopted, that is, there is a main control layer device to coordinate and manage its lower level control layer devices. Type structure supports two levels and above. The control layer device centrally controls the forwarding behavior and policies of network data, including but not limited to the following control functions: network flow control, routing control, scheduling control, policy management, etc.; each control module can support algorithms, protocols, policies The replacement of etc., that is, support for software definition. The control layer equipment uses the global information to manage and control the network, and make decisions on resource scheduling and routing.

The global information that the control layer device can grasp includes but is not limited to: the location information of the data forwarding layer device (indicating the current location of the data forwarding layer device, which can be expressed in longitude and latitude, uploaded by the data forwarding layer device itself or passed by the traffic management agency) monitoring means) and trajectory information (including past trajectory information and future trajectory information).

Since the control layer equipment can make scheduling decisions from a global perspective, the accuracy of routing and scheduling (referring to the probability of ensuring that data packets can be delivered without loss) must be much higher than only relying on local information or even only relying on single-node information. VANET for distributed routing decisions.

Data forwarding layer:

The data forwarding layer is composed of data forwarding layer devices. There are two types of data forwarding layer devices: vehicle nodes and network-related roadside units (Road-Side Unit, RSU, which refers to a device built on urban roads, with wireless communication functions, and used to collect data from the Internet of Vehicles). , which is a well-known term in the research field related to the Internet of Vehicles). Among them, the position of the vehicle node is not fixed, and its future trajectory information indicates the trajectory to be driven, which is represented by information including the driving section, driving direction, driving speed, etc.; This information is not obtained when the user does not allow such uploads. The location of the roadside device is fixed, and its future trajectory information is empty.

Due to the large network scale of the Internet of Vehicles, network clustering (also called partitioning, etc.) management can be implemented for the data forwarding layer devices, and the case of no clustering can be regarded as a network with only one cluster. Network clustering can be based on a variety of clustering logic: it can be divided according to geographical areas, for example, cities can be divided into 10 × 10 km grids, and the vehicles in each grid can be grouped into a cluster and assigned The corresponding control layer equipment is managed; it can also be divided according to the functional attributes of the data forwarding layer equipment, for example, all 9 buses in the city can be divided into one cluster, or all taxis of a company can be divided into one cluster. And assign the corresponding control layer equipment for management. The management method of network clustering can reduce the management burden of each control layer device and improve its response speed, and is also conducive to more accurate control of network resources. When different clusters are managed by different control layer devices, they need to be finally managed by a global control layer device, so as to ensure the global synchronization of some information and coordinate the cross-region handover of vehicle nodes in the data forwarding layer device.

In the present invention, the control layer exchanges information with the application layer through the northbound interface, and exchanges information with the data forwarding layer through the southbound interface (SBI). The SBI is responsible for transmitting control and notification messages, because such messages have high real-time performance. requirements, can be transmitted over a long-range cellular wireless communication network. The data transmission between the data forwarding layer devices adopts the short-distance wireless communication network to realize peer-to-peer and multi-hop transmission.

In combination with the above description of the network architecture of the present invention, the most critical interface protocol in the software-defined architecture, that is, the southbound interface protocol, will be specifically introduced below.

In the embodiment of the present invention, the currently widely used OpenFlow protocol is extended to serve as the southbound interface protocol of the network architecture of the present invention, and the improved version is hereinafter referred to as V-OpenFlow for short.

In the embodiment of the present invention, the southbound interface protocol defines the port (that is, the wireless interface), the flow table, the communication channel, and the communication process at the data forwarding level. The protocol process requires a total of 30 message types, which are used to implement communication channel establishment and channel maintenance. , port feature acquisition, abnormal packet reporting, issuing flow table, deleting flow table and other functions. Among them, most of the messages still use the message types defined by the OpenFlow protocol, and only the changed message types are described below.

Multipart reply message:

During network initialization, the control layer device initializes the network through initialization control signaling and obtains node information, wherein the acquisition of node information is completed by the interaction of "Multipart request/reply message". In the OpenFlow protocol, the "Multipart request/reply message" is used to obtain the port information of the data plane node. V-OpenFlow uses the experimenter field to extend it to describe the port information and status information of the data forwarding layer device.

Among them, the "Multipart request message" does not need to be expanded; and the "Multipart reply message" is sent by the data forwarding layer device, which should carry the port information and status information of the data forwarding layer device. Therefore, the ofp_experimenter_structure structure is used for expansion, and the structure is as follows :

struct ofp_experimenter_structure{

uint32_t experimenter;

uint32_t exp_type;

uint8_t experimenter_data[0];

};

Among them, the experimenter field is the ID of the message;

The exp_type field identifies the type of structure, which can be identified by a preset string;

experimenter_data[0] is an extensible content field. In the present invention, information such as location, driving speed, and cache capacity are added to this field. As a preferred implementation, its name and structure 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;

};

Among them, type=OFPPDPT_EXPERIMENTER, indicating that this structure is an extended message;

length represents the length of the structure;

moving_speed represents the current speed;

caching_capacity represents the remaining cache capacity of the node;

pad[2] is the padding bit;

location represents the location of the vehicle, which is represented by latitude and longitude. The specific structure is as follows:

struct location{

uint8_t altitude;

uint8_t longitude;

}

Echo request message:

In the OpenFlow protocol, after the control layer device and the data forwarding layer device establish a control communication channel, the communication channel is maintained through the "Echo request/reply message", and at the same time, the information is used to control the short-range wireless link. That is, the sending of the Hello message is allowed or prohibited by issuing commands through the "Echo Request Message".

When the data forwarding layer device has a data packet that needs to be sent, it first sends a "Packet_In message" to the control layer device. The control layer device, according to the address information in the message body, combined with the overall situation of the network, according to the currently determined routing rules, Determine the next hop node (set) of the data packet, and send its flow table decision through the "Flow_Mod message". After obtaining the flow table, the data forwarding layer device knows the next hop node of the data packet, and waits for the establishment of the short-distance wireless link. The control layer device uses the global location information of the node and according to the currently adopted judgment rules, when it is believed that the node can meet its designated next hop in the future section, it sends a command through the link hold message "Echo message" to enable the short-distance Hello message. Sending the message (that is, authorizing the establishment of a short-distance wireless link); the data forwarding layer device can use the Hello message to establish a short-distance wireless link with its selected next-hop node, and complete the delivery of the data packet.

In V-OpenFlow, it is necessary to extend the "Echo request message" to implement communication channel maintenance and link establishment command delivery. The following is an introduction:

The structure of the echo request message is as follows:

struct ofp_echo{

struct ofp_header;

uint8_t echo_data[0];

}

Among them, 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;

}

Among them, opf_port represents the ID of the port that is allowed to establish a peer-to-peer opportunity link;

switch represents whether to enable the sending of Hello messages between data forwarding layer nodes. The value is on or off.

The software-defined network-based IoV architecture of the present application and the southbound interface protocol therein have been described in detail above. The data transmission method of the present invention is implemented based on this architecture, and is described in detail below with reference to FIG. 2 .

Referring to FIG. 2, FIG. 2 is a flowchart of a method for data transmission in the Internet of Vehicles based on a software-defined network according to an embodiment of the present invention. The Internet of Vehicles includes an application layer, a control layer, and a data forwarding layer; the control layer passes through the northbound interface and the southbound interface respectively. Carry out information exchange with the application layer and the data forwarding layer; as shown in Figure 2, the method includes the following steps:

Step 201: The control layer device acquires the location information and future trajectory information of all data forwarding layer devices.

The data forwarding layer equipment includes vehicle nodes and roadside devices.

The control layer equipment can obtain the location information and future trajectory information of all vehicle nodes and roadside devices when the vehicle network is initialized. Since the vehicle node is mobile and the location is not fixed, it is necessary to regularly report its own location information and future trajectory information to the control layer device, so that the control layer device can update the vehicle node's location information and future trajectory information in time, so as to accurately control the global information.

Step 202: When the control layer device learns that the data forwarding layer device needs to send a data message, it determines whether the data message needs to be transmitted through the long-distance cellular wireless communication network, and if so, instructs the data forwarding layer device to forward the data message from the cellular interface, Otherwise, a flow table corresponding to the data packet is generated according to the location information and future trajectory information of the data forwarding layer device and sent to the data forwarding layer device, so that the data forwarding layer device forwards the data packet based on the flow table, and realizes the transmission of the data packet. Short-range wireless communication.

When the data forwarding layer device generates a data packet of a data stream or receives a data packet of a data stream and needs to forward it, it sends an RTS (Ready to Send) packet to the control layer device, and the control layer device receives it. At this RTS message, it is determined/learned that the data forwarding layer device needs to send a data message. The RTS message is equivalent to the aforementioned Packet_In message.

In practical applications, data packets cannot be forwarded without limit, so there is a limit on the number of forwarding hops. In this embodiment, the short-range wireless communication network (that is, the network using the wireless short-range technology) is preferentially used to transmit data packets, that is, the wireless short-range technology is used to peer the data packets among the data forwarding layer devices, Multi-hop transmission. However, if the data packet has been forwarded for many 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 send the data packet back to the server via a wired or wireless network), at this time It is necessary to consider giving up using a short-range wireless communication network to transmit data packets, and then choose to use a long-distance cellular wireless communication network (ie, a cellular network) to transmit data packets.

Therefore, in the present invention, a maximum forwarding hop count is preset, and a field carrying the transmission hop count of the data message (ie, the forwarded hop count/number of times) is set in the RTS message. After the control layer device receives the RTS packet sent by the data forwarding layer device, it can determine the subsequent forwarding control behavior according to the comparison result between the transmission hop count of the data packet carried in the RTS packet and the preset maximum forwarding hop count Specifically, if the number of transmission hops of the data message carried in the RTS message is greater than the preset maximum number of forwarding hops, 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 to continue to pass the short-distance Wireless communication networks transmit data packets.

When the data packet needs to be transmitted through the long-distance cellular wireless communication network, the control layer device may notify the data forwarding layer device to send the data packet through the cellular interface. When a data packet needs to be transmitted through a short-distance wireless communication network, the control layer device must first generate a flow table corresponding to the data packet according to the location information and future trajectory information of the data forwarding layer device, and deliver the flow table to the data forwarding layer device. , so that the data forwarding layer device forwards data packets based on the flow table. Wherein, the flow table includes one or more next hop information.

Short-range wireless communication is applied between devices with similar distances. In the present invention, the current data forwarding layer device realizes short-range wireless communication by sending data packets to other nearby data forwarding layer devices. Other data forwarding layer devices that are close to the forwarding layer device can be used as the next hop of the data packet. However, since the location information of the vehicle nodes in the data forwarding layer device changes with the future trajectory, the data forwarding layer devices that are currently close in distance may gradually become more distant, while the data forwarding layer that is far away equipment, it may also gradually approach. Therefore, when determining the next hop of a data packet, it is necessary to take into account the location information and future trajectory information of the data forwarding layer device. Only other data forwarding layer devices that are relatively close to the current data forwarding layer device and tend to shorten in the future are more suitable as The next hop of the data packet.

In this embodiment, the method for generating a flow table corresponding to a data packet according to the location information and future trajectory information of the data forwarding layer device may specifically be: determining the distance to the data forwarding layer device according to the location information of the data forwarding layer device a first data forwarding layer device set within a preset distance range; a second data forwarding layer device set whose distance from the data forwarding layer device tends to be shortened is determined based on the future trajectory information of the data forwarding layer device; the first set of data forwarding layer devices is calculated For the intersection of the data forwarding layer device set and the second data forwarding layer device set, all the data forwarding layer device information in the intersection operation result is written into the flow table corresponding to the data packet as next hop information.

It should be noted that the above is only a specific method for generating a flow table. In fact, other implementation methods can also be used, as long as the next hop in the flow table can be guaranteed to be closer to the current data forwarding layer device and to the current data forwarding layer. The distance between the devices tends to decrease.

In the present invention, data forwarding between data forwarding layer devices relies on short-distance wireless communication technology, and before communication, a wireless link between data forwarding layer devices needs to be established, and the wireless link between data forwarding layer devices needs to be established. The establishment process is significantly different from that of a wireless link in any other architecture:

In the Internet of Vehicles environment, the establishment of wireless links between nodes (data forwarding layer devices in the present invention) under other network architectures can be divided into two categories: pure deterministic and pure opportunistic; among them,

Pure determinism means that the control layer device relies on the mastery of the node position in the global information. When the two nodes are within the communication radius of each other through GPS information, they are authorized to establish a communication link. At this time, the two nodes will initiate Link establishment process or direct broadcast to send data packets;

Pure opportunistic means that in the absence of global information, vehicles continuously broadcast Hello packets and establish links with nodes that can receive Hello packets and feedback.

The defects of the above two are very obvious: the former is centralized control, which requires the control layer equipment to obtain and globally calculate real-time information such as GPS very frequently. While such behavior requires a lot of overhead, there are also the following problems: 1) Impossible It is used for large-scale networks; 2) the loss or delay of some frames will cause the loss of transmission efficiency, and the situation of frame loss and delay is very common. Relatively speaking, although the latter's fully distributed control avoids the drawbacks of centralized control, such a setup process requires massive HELLO message broadcasts, which is prone to waste of resources. In other densely populated areas, resources may be unreasonably used due to the collision of Hello packets and channel contention.

In the present invention, a method for establishing a wireless link combining deterministic and opportunistic is adopted. First, the control layer device is required to grasp the position information of the data forwarding layer device, and the vehicle nodes in the data forwarding layer device are required to be periodically (the time length of one cycle) For T) to report its own location information, the value of T can be determined according to the network scale, etc., and can be much larger than the reporting interval required in the purely deterministic method; Only when the control layer device is authorized will it start sending Hello packets, and only establish a 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 location information and future trajectory information of the data forwarding layer device, and then judges the data forwarding layer device and each flow table in the flow table. Whether the connection authorization conditions are met between the next hops (using the Echo request message to achieve authorization), if the connection authorization conditions are met, the data forwarding layer device is authorized to establish a connection with the next hop, so that the data forwarding layer device receives After being authorized by the control layer device, the operation data forwarding layer device that establishes the connection with the next hop starts to be executed.

in,

After the control layer device generates the flow table corresponding to the data message, 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 a roadside device, determine the The data forwarding layer device and the roadside device meet the connection authorization conditions; if the data forwarding layer device and the next hop are located in the same driving section, and the driving direction of the data forwarding layer device is opposite to each other, then the data forwarding layer device is determined. The connection authorization condition is met between the device and the next hop; otherwise, it is determined that the connection authorization condition is not met between the data forwarding layer device and the next hop, where the same driving section means that there are only two intersections for vehicles to drive on a road away.

After the data forwarding layer device receives the authorization of the connection between the data forwarding layer device and a certain next hop from the control layer device, it starts to establish a connection with a certain next hop. The specific method is: broadcast Hello packets to the outside. , and after receiving the response packet returned by the next hop, establish a connection with the next hop. And after establishing the connection with the next hop, stop broadcasting Hello packets to the outside until the connection authorization between the data forwarding layer device and other next hops is received.

In this embodiment, after the control layer device generates the flow table corresponding to the data packet and delivers the flow table to the data forwarding layer device, the data forwarding layer device can forward the data packet based on the flow table. Therefore, if there is a roadside device in the next hop, the packet will be sent to the roadside device preferentially. Therefore, the specific forwarding method is: determine all the downstream devices that have established a connection with the data forwarding layer device. One hop, if the next hop is a roadside device, the data packet is forwarded to the next hop through the established connection with the next hop, otherwise, the next hop is selected, and the established connection with the next hop A hop connection forwards data packets to the next hop.

In this embodiment, since the roadside device is the target device of the data message, once the roadside device receives the data message, it does not need to continue to transmit the data message in the network. Therefore, in the RTS message Set the field that carries the data packet information, where the data packet information can represent the data packet. When the data forwarding layer device receives a data packet sent by other data forwarding layer devices, if the data forwarding layer device is a roadside device, it will report the received data packet to the control layer device. At this time, the control layer device can Set a rule for discarding the data packet, and when the RTS packet carrying the data packet information is received again, notify the data forwarding layer device that sent the RTS packet to discard the data packet according to the rules for discarding the data packet , so that the data packet will not continue to be transmitted in the network.

The present invention also provides a software-defined vehicle networking data transmission device, which will be described in detail below with reference to FIG. 3 .

Referring to FIG. 3, FIG. 3 is a schematic structural diagram of a software-defined Internet of Vehicles data transmission device according to an embodiment of the present invention. The Internet of Vehicles includes an application layer, a control layer, and a data forwarding layer; the control layer communicates with the northbound interface, the southbound interface, and the The application layer and the data forwarding layer exchange information; the device is applied to the control layer equipment, including:

an acquisition unit 301, configured to acquire location information and future trajectory information of all data forwarding layer devices;

The decision-making unit 302 is used to determine whether the data packet needs to be transmitted through the long-distance cellular wireless communication network when the device at the data forwarding layer needs to send a data packet, and if so, instruct the device at the data forwarding layer to forward the data packet from the cellular interface, Otherwise, a flow table corresponding to the data packet is generated according to the location information and future trajectory information of the data forwarding layer device and sent to the data forwarding layer device, so that the data forwarding layer device forwards the data packet based on the flow table, and realizes the transmission of the data packet. Short-range wireless communication.

In the device shown in Figure 3,

The data forwarding layer equipment includes vehicle nodes and roadside devices;

The obtaining unit 301 is used to obtain the position information and future trajectory information of all vehicle nodes and roadside devices when the Internet of Vehicles is initialized, and the position information of the vehicle node according to the position information and future trajectory information periodically reported by each vehicle node. and future trajectory information to be updated.

In the device shown in Figure 3,

The decision-making unit 302, when receiving the ready to send RTS message sent by the data forwarding layer device, learns that the data forwarding layer device needs to send a data message;

The decision-making unit 302, after receiving the 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 the preset maximum forwarding hop count, and if so, determines that it is necessary to pass the long number of forwarding hops. The data packet is transmitted from the cellular wireless communication network, otherwise, it is determined not to transmit the data packet through the long-distance cellular wireless communication network.

In the device shown in Figure 3,

The future trajectory information of the vehicle node includes: the driving section, driving direction, and driving speed of the vehicle node; the future trajectory information of the roadside device is empty;

the flow table includes next hop information;

The method for generating the flow table corresponding to the data packet according to the location information and future trajectory information of the data forwarding layer device by the decision unit 302 is: according to the location information of the data forwarding layer device, determine that the distance from the data forwarding layer device is in advance. set a first data forwarding layer device set within a distance range; determine a second data forwarding layer device set whose distance from the data forwarding layer device tends to shorten based on the future trajectory information of the data forwarding layer device; calculate the first data For the intersection of the forwarding layer device set and the second data forwarding layer device set, all the data forwarding layer device information in the intersection operation result is written into the flow table corresponding to the data packet as next hop information.

In the device shown in Figure 3,

The decision-making unit 302, after generating the flow table corresponding to the data message of the data forwarding layer device, is further used for: judging whether the connection authorization condition is met between the data forwarding layer device and each next hop in the flow table; If the authorization condition is satisfied, the data forwarding layer device is authorized to establish a connection with the next hop, so that the data forwarding layer device performs an operation of establishing a connection with the next hop.

In the device shown in Figure 3,

The decision-making unit 302, when judging whether the connection authorization condition is met between the data forwarding layer device and each next hop in the flow table, is used to: if the next hop is a roadside device, then determine the data forwarding layer device It meets the connection authorization conditions with the roadside device; if the data forwarding layer device and the next hop are located in the same driving section, and the driving direction of the data forwarding layer device is opposite to each other, it is determined that the data forwarding layer device and the next hop are in the same driving section. The connection authorization condition is met between one hop; otherwise, it is determined that the connection authorization condition is not met between the data forwarding layer device and the next hop, wherein the same driving section refers to a section where there are only two intersections for the vehicle to leave .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection.

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,

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 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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