CN107889077B - Rapid data transmission method based on Internet of vehicles technology - Google Patents
Rapid data transmission method based on Internet of vehicles technology Download PDFInfo
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- CN107889077B CN107889077B CN201711058295.8A CN201711058295A CN107889077B CN 107889077 B CN107889077 B CN 107889077B CN 201711058295 A CN201711058295 A CN 201711058295A CN 107889077 B CN107889077 B CN 107889077B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W40/00—Communication routing or communication path finding
- H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
- H04W40/20—Communication route or path selection, e.g. power-based or shortest path routing based on geographic position or location
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W40/00—Communication routing or communication path finding
- H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
- H04W40/22—Communication route or path selection, e.g. power-based or shortest path routing using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W40/00—Communication routing or communication path finding
- H04W40/24—Connectivity information management, e.g. connectivity discovery or connectivity update
- H04W40/248—Connectivity information update
Abstract
The invention discloses a rapid data transmission method based on a vehicle networking technology. The method classifies nodes according to the driving direction of the vehicle and allocates different channels. The vehicle node and the relay node can only communicate in the allocated channel, and the interference of data transmission is reduced. The method also comprises channel switching, and solves the problem of channel switching in the driving process of the vehicle node. The transmission direction limitation of the relay node is stipulated, and the reliability of data is guaranteed and the efficiency and the speed of data transmission are improved through a rapid diffusion method and the priority transmission of the emergency data packet. In addition, the method considers a three-layer network consisting of the vehicle nodes, the relay nodes and the sink nodes.
Description
Technical Field
The invention relates to the technical field of communication, in particular to the technical field of wireless sensor networks, and specifically relates to a rapid data transmission method based on a vehicle networking technology.
Background
In the current life and production, road transportation and traffic activities have occupied the most important position, but with the rapid development of traffic, the number of vehicles on roads is greatly increased, so that a lot of traffic jam and traffic accidents occur. Worldwide, 50 million people die of traffic accidents each year and increase year by year. And thus the internet of vehicles technology is being noticed by more and more people. At present, the development of the internet of vehicles at home and abroad is very rapid, and the concept of the internet of vehicles is firstly proposed by the U.S. department of transportation in the strategy planning book 2010-2014, so that the aim is to establish a comprehensive and multi-mode ground transportation system. The idea of car networking was proposed immediately after japan and europe. China also proposes Internet of vehicles construction in 2010, and is listed as an important project in the national major specialties in the same year. The internet of vehicles technology is to use wireless network technology to realize communication between vehicles or between vehicles and roadside facilities, and realize functions of traffic monitoring, path planning, intelligent reminding and the like, and is widely concerned by domestic and foreign scholars and enterprises at present.
In the vehicle networking vanet (vehicle Ad Hoc network), data is typically transmitted wirelessly. But the vehicle is also moving rapidly during the wireless transmission. Therefore, the real-time requirement of information transmission is one of the key problems which need to be solved urgently in the internet of vehicles, and an efficient routing protocol is essential. To date, some domestic and foreign scholars have achieved some achievements in researching routing methods of ad hoc networks for vehicles, and some scholars prevent communication link interruption caused by too large distance between vehicle nodes by using multiple paths, so that effective and stable data transmission is achieved. Although these approaches can achieve communication in the internet of vehicles to some extent, there are some drawbacks: 1) the reliability of data transmission is improved mainly by utilizing a routing protocol, and the transmission efficiency and the expansion speed of vehicle data are not improved: 2) the test is only carried out under the simulated ideal environment, and the complexity of different roads and the interference of data transmission are not considered.
Disclosure of Invention
The present invention is directed to solve the above technical problems, and an object of the present invention is to provide a fast data transmission method based on the internet of vehicles, which can reduce interference of data transmission and improve efficiency and diffusion speed of data transmission.
In order to achieve the purpose of the invention, the provided rapid data transmission method based on the vehicle networking technology firstly performs initial channel allocation on the vehicle nodes and the relay nodes, the relay nodes and the vehicle nodes perform data transmission in the allocated channels, and the data transmission channels of the vehicle nodes are switched according to the moving state of the vehicle nodes in the data transmission process. The method firstly carries out channel allocation, and the relay node and the vehicle node carry out data transmission in the pre-allocated channels, thereby avoiding mutual interference between the channels and improving the efficiency and the diffusion speed of data transmission.
Specifically, the initial channel allocation specifically includes the following steps:
a1: analyzing electronic map information, dividing the electronic map information into M areas, and numbering each area and all roads in the area by using numbers;
a2: deploying a plurality of relay nodes along two sides of each road from one end of each road, and naming the address of each relay node;
a3: allocating initial channels of relay nodes next to each road according to the driving direction of the vehicle nodes specified by the road;
a4: and allocating the initial channel of the vehicle node according to the driving direction of the vehicle node.
Specifically, the initial channel allocation of the relay node is as follows: the driving direction of a vehicle node specified by a road is north, and an initial channel of a relay node is set as a channel 1; the driving direction of a vehicle node specified by a road is south, and the initial channel of the relay node is set as a channel 2; the driving direction of a vehicle node specified by a road is east, and the initial channel of the relay node is set as a channel 3; the vehicle node travel direction specified by the road is west, and the relay node initial channel is set to channel 4.
Specifically, the initial channel allocation of the vehicle node is as follows: the driving direction of the vehicle node is north, and the initial channel of the vehicle node is set as a channel 1; the driving direction of the vehicle node is south, and the initial channel of the vehicle node is set as a channel 2; the driving direction of the vehicle node is east, and the initial channel of the vehicle node is set as a channel 3; the driving direction of the vehicle node is west, and the initial channel of the vehicle node is set as a channel 4.
Specifically, the relay node address naming adopts the following mode: the 1 st to 4 th bytes are serial numbers of the areas; bytes 5-8 are the serial numbers of roads in the area; the 9 th byte to the 12 th byte are serial numbers of the relay nodes on the current road; the 13 th byte is the channel number.
Specifically, the relay node and the vehicle node perform data transmission in the allocated channel, and the data transmission follows the following steps:
b1: initializing parameters: initializing queues and routing tables of the relay nodes and the vehicle nodes, and selecting corresponding channels according to an initial channel allocation method;
b2: broadcasting a data packet: the relay node and the vehicle node respectively judge the states of the relay node and the vehicle node, and broadcast a relay node data packet and a vehicle node data packet which comprise a source address, a target address, a data packet number, a data packet hop number, position information of the source node, data sent by the source node and a check bit;
b3: receiving a data packet: according to the difference between the receiving body and the received object, one of the following steps is respectively executed:
1. when a relay node receives a relay node data packet, firstly judging whether the relay node address in the data packet is larger than the self node address; if the number of the relay nodes is larger than the preset value, sending a self data packet, updating a self routing table according to the information in the received relay node data packet, and otherwise, not sending the self data packet; secondly, judging the emergency zone bit of the received relay node data packet, and executing the following steps according to the judgment result:
1-1: if the emergency flag bit of the relay node data packet is not 1, executing the step 1-3, otherwise, judging whether the forwarding hop count of the received emergency data packet is less than 7 for the emergency data packet, and if the forwarding hop count is less than 7, executing the step 1-2; if not less than 7, go to step B4;
1-2: analyzing whether the next forwarding node in the emergency data packet is the node of the forwarding node, if so, storing the data in the emergency data packet into an emergency queue of the forwarding node, and executing the step B4; if not, directly executing the step B4;
1-3: judging whether the forwarding hop count of the relay node data packet is less than 5, if so, storing the data in the data packet into a conventional queue per se, and jumping to the step B4; if not less than 5, directly jumping to the step B4;
2. the relay node receives the vehicle node data packet and feeds back the relay node data packet; analyzing the emergency flag bit of the received vehicle node data packet, judging whether an emergency occurs to the vehicle node, if the emergency flag bit of the vehicle node data packet is 1, the emergency occurs to the vehicle node, storing the vehicle node data into an emergency queue, and jumping to the step B5; otherwise, storing the vehicle node data into a conventional queue and jumping to the step B5;
3. the vehicle node receives the relay node data packet, judges whether the relay node data packet is consistent with a relay node channel inquired in the electronic map or not, if so, the verification is passed, the routing table of the vehicle node is updated, the driving condition of the vehicle is analyzed according to the electronic map and the driving state of the vehicle, and the data transmission channel of the vehicle node is switched; otherwise, searching the address of the relay node which is on the right side of the road where the current vehicle node is located and is closest to the road;
b4: judging whether the emergency queue has emergency data waiting for transmission, if so, immediately transmitting the emergency data packet by using a fast diffusion method, and jumping to the step B5; if not, directly jumping to the step B5;
b5: judging whether the emergency queue is empty and the conventional queue has conventional data waiting to be sent, if so, transmitting the conventional data to a rear relay node with the farthest physical position in the routing table, and jumping to the step B2; otherwise, go directly to step B2.
Specifically, the rapid diffusion method is as follows:
in the routing table, determining a current relay node and a relay node with the farthest physical position in the routing table, selecting the relay node as a next forwarding node, and broadcasting and sending a data packet; if the data packet of other relay nodes is received, whether the data packet is used as the next forwarding node of the data packet is judged according to the information in the data packet, if so, the received data packet is sent in a broadcast mode, otherwise, the data packet of other relay nodes is monitored, and the data packet is not forwarded.
Specifically, the data transmission channel of the switched vehicle node is switched according to the driving state of the vehicle node and the road condition on which the vehicle node is driven, and the specific mode is as follows:
1. if the vehicle does not change the driving road along the current road, judging the current road condition according to the electronic map and the driving state of the vehicle, and performing one of the following steps according to the road condition:
1) if the current road allows straight going and turning around, the vehicle node does not switch channels when the vehicle node passes through the intersection in the straight going way, and still transmits data in the current channel; if the current road allows left turn, straight going and turning around, the vehicle node does not switch channels when passing through the intersection in straight going, and still transmits data in the current channel;
2) if the current road allows right turn, straight going and turning around, when the vehicle node passes through the intersection in straight going, the vehicle node is sequentially switched to a relay node channel with the relay node number 1 of the road corresponding to the running direction of the current vehicle node and a relay node channel of the reverse road of the current road, a data packet is respectively sent, and the vehicle is switched back to the current road channel for data transmission after passing through the intersection in straight going;
3) if the current road allows left turning, right turning, straight going and turning around, when the vehicle node passes through the intersection in a straight going way, the vehicle node is sequentially switched to two channels of the right side relay node of the two roads corresponding to the running direction of the current vehicle node and the relay node channel of the reverse road of the current road, and a data packet is respectively sent, and the vehicle is switched back to the channel of the current road for data transmission after passing through the intersection in a straight going way;
2. if the vehicle turns around to change the driving road, a data packet is sent to the relay node of the current road when the vehicle turns around, and the vehicle is switched to the relay node channel of the reverse road for data transmission after turning around;
3. if the vehicle turns left along the current road to change the driving road, judging the current road condition according to the electronic map and the driving state of the vehicle, and performing one of the following steps according to the road condition:
1) if the current road allows left turning and right turning, when the vehicle turns left and passes through the intersection, switching to the channels of the right side relay nodes of the two roads corresponding to the current vehicle node driving direction to send a data packet, and after the vehicle turns to the left side road, switching to the channel of the right side relay node of the road corresponding to the current vehicle node driving direction to transmit data;
2) if the current road allows left turn, straight going and turning around, when the vehicle turns left and passes through the intersection, sequentially switching to a relay node channel with the relay node number 1 on the left road corresponding to the vehicle running direction and a relay node channel on the reverse road of the current road according to the vehicle running direction, respectively sending a data packet, and switching to a right relay node channel of the corresponding lane for data transmission after the left turn passes through the intersection;
3) if the current road allows left turn, right turn, straight going and turning around, when the vehicle turns left and passes through the intersection, the vehicle is sequentially switched to two channels of the right relay nodes of the two roads corresponding to the driving direction of the current vehicle node and the relay node channel of the reverse road of the current road, and the two channels are respectively used for sending a data packet and are switched to the channel of the right relay node of the corresponding lane for data transmission after the left turn passes through the intersection;
4. if the vehicle changes the driving road along the right turn of the current road, judging the current road condition according to the electronic map and the driving state of the vehicle, and performing one of the following steps according to the road condition;
1) if the current road allows left turning and right turning or the current road allows left turning, right turning, straight going and turning around, when the vehicle turns right and passes through the intersection, the vehicle is sequentially switched to two channels of the right relay nodes of the two roads corresponding to the driving direction of the current vehicle node, one data packet is respectively sent, and after the vehicle is switched to the right road of the current road, the vehicle is switched to the channel of the right relay node corresponding to the driving direction of the vehicle node for data transmission;
2) if the current road allows right turn, straight going and turning around, when the vehicle turns right and passes through the intersection, the vehicle is switched to the channel of the right relay node of the current road for data transmission;
5. and if the vehicle is in other special road conditions, switching to the channel of the relay node on the right side of the current road for data transmission.
Specifically, the format of the data packet is as follows:
the 1 st to 8 th bits are source addresses; the 9 th to 16 th bits are target addresses; the 17 th to 24 th bits are data packet numbers; the 25 th to 28 th bits are data packet hop numbers; the 29 th to 32 th bits are position information of the source node; the 33 th to 50 th bits are data sent by the source node; the 51 th bit is an emergency flag bit, when the emergency flag bit is 0, the current data packet is represented as a conventional data packet, and when the emergency flag bit is 1, the current data packet is represented as an emergency data packet; bits 52-53 are check bits.
Compared with the prior art, the invention has the following beneficial effects: the nodes are classified according to the driving direction of the vehicle, and different channels are allocated. The vehicle node and the relay node can only communicate in the allocated channel, and the interference of data transmission is reduced. The method also comprises channel switching, and solves the problem of channel switching in the driving process of the vehicle node. The transmission direction limitation of the relay node is stipulated, and the reliability of data is guaranteed and the efficiency and the speed of data transmission are improved through a rapid diffusion method and the priority transmission of the emergency data packet. The method improves the transmission time of the information and is suitable for the rapidly changing vehicle running environment. In addition, the method considers a three-layer network consisting of the vehicle nodes, the relay nodes and the sink nodes.
Drawings
FIG. 1 is a flow chart of initial channel allocation according to the present invention;
FIG. 2 is a flow chart of data transmission according to the present invention;
FIG. 3 is an exemplary illustration of a straight road analysis of the present invention;
FIG. 4 is an exemplary diagram of a T-shaped road analysis according to the present invention;
FIG. 5 is an exemplary illustration of an intersection analysis of the present invention.
Detailed Description
The technical solution of the present invention is further described in detail with reference to the accompanying drawings.
Referring to fig. 1 to 5, the present invention considers not only a vehicle node, a relay node, but also a sink node, and the three nodes together form a three-layer network structure, and provides a fast data transmission method based on the internet of vehicles technology. In the practical application process, the base station or the user does not directly send signals to each other, but the signals are amplified or regenerated by the relay node for forwarding through the relay node. The vehicle node is an automobile driven by people, a positioning device such as a GPS locator is integrated on the vehicle node, and the driving direction of the vehicle node is defined as follows: when the included angle between the driving direction of the vehicle node and the due north direction is less than or equal to 45 degrees, the driving direction of the vehicle node is north; when the included angle between the driving direction of the vehicle node and the south-pointing direction is less than or equal to 45 degrees, the driving direction of the vehicle node is south; when the included angle between the driving direction of the vehicle node and the east-righting direction is less than 45 degrees, the driving direction of the vehicle node is east; and when the included angle between the driving direction of the vehicle node and the right west direction is less than 45 degrees, the driving direction of the vehicle node is west.
The channel allocation described in the above method may adopt any existing method; as shown in fig. 1, the channel allocation method provided herein is as follows:
a1: analyzing electronic map information, dividing the electronic map information into M areas, and numbering each area and all roads in the area by using numbers;
a2: a plurality of relay nodes which are equally spaced or unequally spaced are arranged at one end of each road along two sides of the road, for example, the interval between two relay nodes is 350 m; after the relay nodes are deployed, naming the addresses of the relay nodes; the naming mode of the relay node can adopt any one of the existing modes, and the naming mode adopted in the application is as follows: the 1 st to 4 th bytes are serial numbers of the areas; bytes 5-8 are the serial numbers of roads in the area; the 9 th byte to the 12 th byte are serial numbers of the relay nodes on the current road; the 13 th byte is a channel number;
a3: allocating initial channels of relay nodes which are close to the road or closest to the road according to the driving direction of the vehicle nodes specified by each road; the relationship between the initial channel of the relay node and the road-specified vehicle node travel direction may be arbitrary, for example: when the driving direction of the vehicle node specified by the road is north, setting the initial channel of the relay node as a channel 1; when the driving direction of the vehicle node specified by the road is south, setting the initial channel of the relay node as a channel 2; when the driving direction of the vehicle node specified by the road is east, setting the initial channel of the relay node as a channel 3; when the vehicle node travel direction specified by the road is west, the relay node initial channel is set to channel 4. Of course, in addition to the above-described assumption, the initial channel of the relay node may be arbitrarily allocated according to a predetermined vehicle traveling direction.
A4: the satellite positioning module is utilized to analyze the driving direction of the vehicle node and perform initial channel allocation on the vehicle node, and the initial channel of the vehicle node can be arbitrarily allocated, for example: the driving direction of the vehicle node is north, and the initial channel of the vehicle node is set as a channel 1; the driving direction of the vehicle node is south, and the initial channel of the vehicle node is set as a channel 2; the driving direction of the vehicle node is east, and the initial channel of the vehicle node is set as a channel 3; the driving direction of the vehicle node is west, and the initial channel of the vehicle node is set as a channel 4.
After the initial channels of the relay nodes and the vehicle nodes are distributed, data transmission is carried out between the relay nodes and the vehicle nodes through the distributed channels, and the relay nodes finally transmit related data to the base station for a control center or a monitoring center to use. Data transmission between the relay nodes and the vehicle nodes follows certain steps, as shown in fig. 2; the following steps were followed:
b1: initializing parameters: initializing queues and routing tables of the relay nodes and the vehicle nodes, and selecting corresponding channels according to an initial channel allocation method;
b2: broadcasting a data packet: the relay node and the vehicle node respectively judge the states of the relay node and the vehicle node, and broadcast a relay node data packet and a vehicle node data packet which comprise a source address, a target address, a data packet number, a data packet hop number, position information of the source node, data sent by the source node and a check bit;
b3: receiving a data packet: according to the difference between the receiving body and the received object, one of the following steps is respectively executed:
1. when a relay node receives a relay node data packet, firstly judging whether the relay node address in the data packet is larger than the self node address; if the number of the relay nodes is larger than the preset value, sending a self data packet, updating a self routing table according to the information in the received relay node data packet, and otherwise, not sending the self data packet; secondly, judging the emergency zone bit of the received relay node data packet, and executing the following steps according to the judgment result:
1-1: if the emergency flag bit of the relay node data packet is not 1, executing the step 1-3, otherwise, judging whether the forwarding hop count of the received emergency data packet is less than 7 for the emergency data packet, and if the forwarding hop count is less than 7, executing the step 1-2; if not less than 7, go to step B4;
1-2: analyzing whether the next forwarding node in the emergency data packet is the node of the forwarding node, if so, storing the data in the emergency data packet into an emergency queue of the forwarding node, and executing the step B4; if not, directly executing the step B4;
1-3: judging whether the forwarding hop count of the relay node data packet is less than 5, if so, storing the data in the data packet into a conventional queue per se, and jumping to the step B4; if not less than 5, directly jumping to the step B4;
2. the relay node receives the vehicle node data packet and feeds back the relay node data packet; analyzing the emergency flag bit of the received vehicle node data packet, judging whether an emergency occurs to the vehicle node, if the emergency flag bit of the vehicle node data packet is 1, the emergency occurs to the vehicle node, storing the vehicle node data into an emergency queue, and jumping to the step B5; otherwise, storing the vehicle node data into a conventional queue and jumping to the step B5;
3. the vehicle node receives the relay node data packet, judges whether the relay node data packet is consistent with a relay node channel inquired in the electronic map or not, if so, the verification is passed, the routing table of the vehicle node is updated, the driving condition of the vehicle is analyzed according to the electronic map and the driving state of the vehicle, and the data transmission channel of the vehicle node is switched; otherwise, searching the address of the relay node which is on the right side of the road where the current vehicle node is located and is closest to the road;
b4: judging whether the emergency queue has emergency data waiting for transmission, if so, immediately transmitting the emergency data packet by using a fast diffusion method, and jumping to the step B5; if not, directly jumping to the step B5;
b5: judging whether the emergency queue is empty and the conventional queue has conventional data waiting to be sent, if so, transmitting the conventional data to a rear relay node with the farthest physical position in the routing table, and jumping to the step B2; otherwise, go directly to step B2.
In the data transmission step, the broadcasted relay node data packet and the broadcasted vehicle node data packet respectively include:
the 1 st to 8 th bits are source addresses; the 9 th to 16 th bits are target addresses; the 17 th to 24 th bits are data packet numbers; the 25 th to 28 th bits are data packet hop numbers; the 29 th to 32 th bits are position information of the source node; the 33 th to 50 th bits are data sent by the source node; the 51 th bit is an emergency flag bit, when the emergency flag bit is 0, the current data packet is represented as a conventional data packet, and when the emergency flag bit is 1, the current data packet is represented as an emergency data packet; bits 52-53 are check bits.
The data transmission adopted by the application is that in a relay node routing table, a relay node with the farthest physical position in the current relay node and the routing table is determined, the relay node is selected as the next forwarding node, and a data packet is broadcast and sent; if the data packet of other relay nodes is received, whether the data packet is used as the next forwarding node of the data packet is judged according to the information in the data packet, if so, the received data packet is sent in a broadcast mode, otherwise, the data packet of other relay nodes is monitored, and the data packet is not forwarded.
Since the driving direction of the vehicle node can be changed at any time during the moving process, various convergence intersections such as straight intersections, crossroads and T-shaped intersections can be encountered. And analyzing the driving condition of the vehicle according to the electronic map and the driving state of the vehicle, and executing the channel switching method. Referring to fig. 3, on a bidirectional travel road, relay nodes B1, B2, B3 and vehicle nodes V3 and V4 communicate using a channel B. The relay nodes a1, a2, A3 and the vehicle nodes V1, V2 communicate using channel a. The vehicle node V4 broadcasts data in channel B, the relay node B2 receives the data and sends a data packet to the relay node B3, and the vehicle node V3 receives data packets of the vehicle node V4 and the front relay node B2; the vehicle node V1 and the vehicle node V2 communicate in channel A without interfering with the B channel. Referring to fig. 4, at a T-junction, a vehicle V1 travels along a road B, and only data needs to be broadcast in a channel B during the travel; the vehicle V2 turns left from the road D to enter the road B, and in the process of driving, the vehicle data is broadcast on the channel B, D in the process of turning left to pass through the T-shaped intersection; vehicle V3 is traveling on road D, broadcasting only on channel D; vehicle V4 passes through the T-junction along road C, broadcasting channel C; vehicle V5 turns right from road D into road C, broadcasting in channel C, D. Referring to fig. 5, at the intersection, the vehicle V1 travels on the road D, and data communication is performed only for the vehicle node and the relay node on the channel; vehicle V2 turns left from road D into road a, turns around to pass other roads, thus broadcasting data in the full channel during the turn; the vehicle V3 enters road a and performs data communication only on channel a; vehicle V4 travels through the intersection on road a, broadcasting data in channel C; the vehicle V5 turns right from road D into road C, having an effect only on channel C and channel D, so data is broadcast only on channel C and channel D.
In order to ensure that the vehicle nodes and the relay nodes at the convergence junctions can also transmit data according to respective channels, the data transmission process also describes the data transmission channel for switching the vehicle nodes, namely the channel switching of the vehicle nodes, if the channel of the running vehicle node is 1, the channel is switched to be 2 at the convergence junctions, or the channel is switched to be the road to which the vehicle node is about to turn and the channel of the relay node closest to the road.
The present embodiment provides a channel switching step implemented based on a state of travel of a vehicle node and a condition of a current road on which the vehicle node travels, specifically as follows:
1. if the vehicle does not change the driving road along the current road, judging the current road condition according to the electronic map and the driving state of the vehicle, and performing one of the following steps according to the road condition:
1) if the current road allows straight going and turning around, the vehicle node does not switch channels when the vehicle node passes through the intersection in the straight going way, and still transmits data in the current channel; if the current road allows left turn, straight going and turning around, the vehicle node does not switch channels when passing through the intersection in straight going, and still transmits data in the current channel;
2) if the current road allows right turn, straight going and turning around, when the vehicle node passes through the intersection in straight going, the vehicle node is sequentially switched to a relay node channel with the relay node number 1 of the road corresponding to the running direction of the current vehicle node and a relay node channel of the reverse road of the current road, a data packet is respectively sent, and the vehicle is switched back to the current road channel for data transmission after passing through the intersection in straight going;
3) if the current road allows left turning, right turning, straight going and turning around, when the vehicle node passes through the intersection in a straight going way, the vehicle node is sequentially switched to two channels of the right side relay node of the two roads corresponding to the running direction of the current vehicle node and the relay node channel of the reverse road of the current road, and a data packet is respectively sent, and the vehicle is switched back to the channel of the current road for data transmission after passing through the intersection in a straight going way;
2. if the vehicle turns around to change the driving road, a data packet is sent to the relay node of the current road when the vehicle turns around, and the vehicle is switched to the relay node channel of the reverse road for data transmission after turning around;
3. if the vehicle turns left along the current road to change the driving road, judging the current road condition according to the electronic map and the driving state of the vehicle, and performing one of the following steps according to the road condition:
1) if the current road allows left turning and right turning, when the vehicle turns left and passes through the intersection, switching to the channels of the right side relay nodes of the two roads corresponding to the current vehicle node driving direction to send a data packet, and after the vehicle turns to the left side road, switching to the channel of the right side relay node of the road corresponding to the current vehicle node driving direction to transmit data;
2) if the current road allows left turn, straight going and turning around, when the vehicle turns left and passes through the intersection, sequentially switching to a relay node channel with the relay node number 1 on the left road corresponding to the vehicle running direction and a relay node channel on the reverse road of the current road according to the vehicle running direction, respectively sending a data packet, and switching to a right relay node channel of the corresponding lane for data transmission after the left turn passes through the intersection;
3) if the current road allows left turn, right turn, straight going and turning around, when the vehicle turns left and passes through the intersection, the vehicle is sequentially switched to two channels of the right relay nodes of the two roads corresponding to the driving direction of the current vehicle node and the relay node channel of the reverse road of the current road, and the two channels are respectively used for sending a data packet and are switched to the channel of the right relay node of the corresponding lane for data transmission after the left turn passes through the intersection;
4. if the vehicle changes the driving road along the right turn of the current road, judging the current road condition according to the electronic map and the driving state of the vehicle, and performing one of the following steps according to the road condition;
1) if the current road allows left turning and right turning or the current road allows left turning, right turning, straight going and turning around, when the vehicle turns right and passes through the intersection, the vehicle is sequentially switched to two channels of the right relay nodes of the two roads corresponding to the driving direction of the current vehicle node, one data packet is respectively sent, and after the vehicle is switched to the right road of the current road, the vehicle is switched to the channel of the right relay node corresponding to the driving direction of the vehicle node for data transmission;
2) if the current road allows right turn, straight going and turning around, when the vehicle turns right and passes through the intersection, the vehicle is switched to the channel of the right relay node of the current road for data transmission;
5. and if the vehicle is in other special road conditions, switching to the channel of the relay node on the right side of the current road for data transmission.
According to the method, a three-layer network consisting of vehicle nodes, relay nodes and sink nodes is considered, the nodes are classified according to the driving direction of the vehicle, and different channels are distributed. The vehicle node and the relay node can only communicate in the allocated channel, and the interference of data transmission is reduced. The method also comprises channel switching, and solves the problem of channel switching in the driving process of the vehicle node. The transmission direction limitation of the relay node is stipulated, and the reliability of data is guaranteed and the efficiency and the speed of data transmission are improved through a rapid diffusion method and the priority transmission of the emergency data packet. The method improves the transmission time of the information and is suitable for the rapidly changing vehicle running environment.
In this specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.
Claims (8)
1. A quick data transmission method based on the car networking technology is characterized in that: the method comprises the following steps that firstly, initial channel allocation is carried out on a vehicle node and a relay node, the relay node and the vehicle node carry out data transmission in an allocated channel, the data transmission channel of the vehicle node is switched according to the moving state of the vehicle node in the data transmission process, the relay node and the vehicle node carry out data transmission in the allocated channel, and the data transmission follows the following steps:
b1: initializing parameters: initializing queues and routing tables of the relay nodes and the vehicle nodes, and selecting corresponding channels according to an initial channel allocation method;
b2: broadcasting a data packet: the relay node and the vehicle node respectively judge the states of the relay node and the vehicle node, and broadcast a relay node data packet and a vehicle node data packet which comprise a source address, a target address, a data packet number, a data packet hop number, position information of the source node, data sent by the source node and a check bit;
b3: receiving a data packet: according to the difference between the receiving body and the received object, one of the following steps is respectively executed:
1. when a relay node receives a relay node data packet, firstly judging whether the relay node address in the data packet is larger than the self node address; if the number of the relay nodes is larger than the preset value, sending a self data packet, updating a self routing table according to the information in the received relay node data packet, and otherwise, not sending the self data packet; secondly, judging the emergency zone bit of the received relay node data packet, and executing the following steps according to the judgment result:
1-1: if the emergency flag bit of the relay node data packet is not 1, executing the step 1-3, otherwise, judging whether the forwarding hop count of the received emergency data packet is less than 7 for the emergency data packet, and if the forwarding hop count is less than 7, executing the step 1-2; if not less than 7, go to step B4;
1-2: analyzing whether the next forwarding node in the emergency data packet is the node of the forwarding node, if so, storing the data in the emergency data packet into an emergency queue of the forwarding node, and executing the step B4; if not, directly executing the step B4;
1-3: judging whether the forwarding hop count of the relay node data packet is less than 5, if so, storing the data in the data packet into a conventional queue per se, and jumping to the step B4; if not less than 5, directly jumping to the step B4;
2. the relay node receives the vehicle node data packet and feeds back the relay node data packet; analyzing the emergency flag bit of the received vehicle node data packet, judging whether an emergency occurs to the vehicle node, if the emergency flag bit of the vehicle node data packet is 1, the emergency occurs to the vehicle node, storing the vehicle node data into an emergency queue, and jumping to the step B5; otherwise, storing the vehicle node data into a conventional queue and jumping to the step B5;
3. the vehicle node receives the relay node data packet, judges whether the relay node data packet is consistent with a relay node channel inquired in the electronic map or not, if so, the verification is passed, the routing table of the vehicle node is updated, the driving condition of the vehicle is analyzed according to the electronic map and the driving state of the vehicle, and the data transmission channel of the vehicle node is switched; otherwise, searching the address of the relay node which is on the right side of the road where the current vehicle node is located and is closest to the road;
b4: judging whether the emergency queue has emergency data waiting for transmission, if so, immediately transmitting the emergency data packet by using a fast diffusion method, and jumping to the step B5; if not, directly jumping to the step B5;
b5: judging whether the emergency queue is empty and the conventional queue has conventional data waiting to be sent, if so, transmitting the conventional data to a rear relay node with the farthest physical position in the routing table, and jumping to the step B2; otherwise, go directly to step B2.
2. The fast data transmission method based on the car networking technology as claimed in claim 1, wherein: the specific steps of the initial channel allocation are as follows:
a1: analyzing electronic map information, dividing the electronic map information into M areas, and numbering each area and all roads in the area by using numbers;
a2: deploying a plurality of relay nodes along two sides of each road from one end of each road, and naming the address of each relay node;
a3: allocating initial channels of relay nodes next to each road according to the driving direction of the vehicle nodes specified by the road;
a4: and allocating the initial channel of the vehicle node according to the driving direction of the vehicle node.
3. The fast data transmission method based on the car networking technology as claimed in claim 2, wherein: the initial channel allocation of the relay node is as follows: the driving direction of a vehicle node specified by a road is north, and an initial channel of a relay node is set as a channel 1; the driving direction of a vehicle node specified by a road is south, and the initial channel of the relay node is set as a channel 2; the driving direction of a vehicle node specified by a road is east, and the initial channel of the relay node is set as a channel 3; the vehicle node travel direction specified by the road is west, and the relay node initial channel is set to channel 4.
4. The fast data transmission method based on the car networking technology as claimed in claim 3, wherein: the initial channel allocation for the vehicle node is as follows: the driving direction of the vehicle node is north, and the initial channel of the vehicle node is set as a channel 1; the driving direction of the vehicle node is south, and the initial channel of the vehicle node is set as a channel 2; the driving direction of the vehicle node is east, and the initial channel of the vehicle node is set as a channel 3; the driving direction of the vehicle node is west, and the initial channel of the vehicle node is set as a channel 4.
5. The fast data transmission method based on the car networking technology as claimed in claim 4, wherein: the relay node address naming adopts the following mode: the 1 st to 4 th bytes are serial numbers of the areas; bytes 5-8 are the serial numbers of roads in the area; the 9 th byte to the 12 th byte are serial numbers of the relay nodes on the current road; the 13 th byte is the channel number.
6. The fast data transmission method based on the car networking technology as claimed in claim 1, wherein: the rapid diffusion method is as follows:
in the routing table, determining a current relay node and a relay node with the farthest physical position in the routing table, selecting the relay node as a next forwarding node, and broadcasting and sending a data packet; if the data packet of other relay nodes is received, whether the data packet is used as the next forwarding node of the data packet is judged according to the information in the data packet, if so, the received data packet is sent in a broadcast mode, otherwise, the data packet of other relay nodes is monitored, and the data packet is not forwarded.
7. The rapid data transmission method based on the car networking technology according to any one of claims 1 to 6, wherein: the data transmission channel of the switching vehicle node is switched according to the driving state of the vehicle node and the road condition driven by the vehicle node, and the specific mode is as follows:
1. if the vehicle does not change the driving road along the current road, judging the current road condition according to the electronic map and the driving state of the vehicle, and performing one of the following steps according to the road condition:
1) if the current road allows straight going and turning around, the vehicle node does not switch channels when the vehicle node passes through the intersection in the straight going way, and still transmits data in the current channel; if the current road allows left turn, straight going and turning around, the vehicle node does not switch channels when passing through the intersection in straight going, and still transmits data in the current channel;
2) if the current road allows right turn, straight going and turning around, when the vehicle node passes through the intersection in straight going, the vehicle node is sequentially switched to a relay node channel with the relay node number 1 of the road corresponding to the running direction of the current vehicle node and a relay node channel of the reverse road of the current road, a data packet is respectively sent, and the vehicle is switched back to the current road channel for data transmission after passing through the intersection in straight going;
3) if the current road allows left turning, right turning, straight going and turning around, when the vehicle node passes through the intersection in a straight going way, the vehicle node is sequentially switched to two channels of the right side relay node of the two roads corresponding to the running direction of the current vehicle node and the relay node channel of the reverse road of the current road, and a data packet is respectively sent, and the vehicle is switched back to the channel of the current road for data transmission after passing through the intersection in a straight going way;
2. if the vehicle turns around to change the driving road, a data packet is sent to the relay node of the current road when the vehicle turns around, and the vehicle is switched to the relay node channel of the reverse road for data transmission after turning around;
3. if the vehicle turns left along the current road to change the driving road, judging the current road condition according to the electronic map and the driving state of the vehicle, and performing one of the following steps according to the road condition:
1) if the current road allows left turning and right turning, when the vehicle turns left and passes through the intersection, switching to the channels of the right side relay nodes of the two roads corresponding to the current vehicle node driving direction to send a data packet, and after the vehicle turns to the left side road, switching to the channel of the right side relay node of the road corresponding to the current vehicle node driving direction to transmit data;
2) if the current road allows left turn, straight going and turning around, when the vehicle turns left and passes through the intersection, sequentially switching to a relay node channel with the relay node number 1 on the left road corresponding to the vehicle running direction and a relay node channel on the reverse road of the current road according to the vehicle running direction, respectively sending a data packet, and switching to a right relay node channel of the corresponding lane for data transmission after the left turn passes through the intersection;
3) if the current road allows left turn, right turn, straight going and turning around, when the vehicle turns left and passes through the intersection, the vehicle is sequentially switched to two channels of the right relay nodes of the two roads corresponding to the driving direction of the current vehicle node and the relay node channel of the reverse road of the current road, and the two channels are respectively used for sending a data packet and are switched to the channel of the right relay node of the corresponding lane for data transmission after the left turn passes through the intersection;
4. if the vehicle changes the driving road along the right turn of the current road, judging the current road condition according to the electronic map and the driving state of the vehicle, and performing one of the following steps according to the road condition;
1) if the current road allows left turning and right turning or the current road allows left turning, right turning, straight going and turning around, when the vehicle turns right and passes through the intersection, the vehicle is sequentially switched to two channels of the right relay nodes of the two roads corresponding to the driving direction of the current vehicle node, one data packet is respectively sent, and after the vehicle is switched to the right road of the current road, the vehicle is switched to the channel of the right relay node corresponding to the driving direction of the vehicle node for data transmission;
2) if the current road allows right turn, straight going and turning around, when the vehicle turns right and passes through the intersection, the vehicle is switched to the channel of the right relay node of the current road for data transmission;
5. and if the vehicle is in other special road conditions, switching to the channel of the relay node on the right side of the current road for data transmission.
8. The fast data transmission method based on the car networking technology as claimed in claim 1 or 6, wherein: the format of the data packet is as follows:
the 1 st to 8 th bits are source addresses; the 9 th to 16 th bits are target addresses; the 17 th to 24 th bits are data packet numbers; the 25 th to 28 th bits are data packet hop numbers; the 29 th to 32 th bits are position information of the source node; the 33 th to 50 th bits are data sent by the source node; the 51 th bit is an emergency flag bit, when the emergency flag bit is 0, the current data packet is represented as a conventional data packet, and when the emergency flag bit is 1, the current data packet is represented as an emergency data packet; bits 52-53 are check bits.
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Denomination of invention: A fast data transmission method based on Internet of vehicles technology Effective date of registration: 20220627 Granted publication date: 20200609 Pledgee: Zhuji Branch of Industrial and Commercial Bank of China Ltd. Pledgor: ZHEJIANG RUXIN INTELLIGENT TECHNOLOGY CO.,LTD. Registration number: Y2022980008876 |