CN105391782B - A kind of V2I/V2V car networking system and its method based on cognition OFDM - Google Patents

Abstract

The invention discloses an OFDM-based V2I/V2V vehicle networking system, which includes a vehicle-mounted unit and a roadside unit, and the vehicle-mounted unit and the roadside unit are configured to use the ISM frequency band for wireless communication, and transmit video, voice, and text data, and provide traffic safety information and traffic condition information to drivers. The present invention also provides a mobile ad-hoc network information transmission method, including the information collection module starts to collect video, sound, text and other information, controls the host module to compress, encode, package, and modulate, and sends the modulated information to the sending queue ; The sending end notifies the receiving end on the control channel that it is about to send data; the receiving end performs spectrum sensing, and feeds back the carrier frequency and subcarrier group with better channel quality to the sending end through the control channel; the receiving end receives a data packet information, demodulate and verify, and obtain the verification information; record the number of consecutive packet loss, and decide whether to perform spectrum sensing according to the number of packet loss.

Description

A V2I/V2V Internet of Vehicles System and Method Based on Cognitive OFDM

technical field

The present invention relates to the field of Internet of Vehicles, in particular to a V2V/V2I Internet of Vehicles system based on cognitive OFDM.

Background technique

The Internet of Things uses advanced communication and networking technologies to connect objects into a network and integrate them into the existing Internet, so that people can interact with wide-area and multi-dimensional information in the real world through the Internet of Things and realize human-machine interaction. The seamless integration of physical environment.

Against the background of the rapid development of the Internet of Things, urban traffic congestion and sustainable development requirements, the Internet of Vehicles has evolved from the Vehicular Ad Hoc Network (VANET) to the era of IoV (Internet of Vehicles). Technologies such as WAVE (Wireless Access in Vehicular Environment) protocol based on IEEE 802.11p and Drive-thru based on IEEE 802.11b have proposed many effective communication and networking solutions for VANET.

In February 2014, the U.S. Transportation Safety Administration officially announced that the Obama administration will mandate that new cars and light trucks be equipped with radio transponders to implement vehicle-to-vehicle interconnection in order to reduce car accidents and losses of people and property. Currently, Google implements the OAA (Open Automotive Alliance) program to build standardization based on Android devices. Apple is also working exclusively with Honda and Hyundai to develop a car-specific iOS7 operating system.

At present, the concurrent speed of the mainstream cellular network is only 100Mbps, and the total amount of in-car data is increasing exponentially. The in-car data urgently needs to be distributed. However, wifi technology is facing shortcomings such as link instability and prolonged switching. The Internet of Vehicles urgently needs to find a network technology to transmit a large amount of information.

In addition, cognitive radio can continuously sense changes in the wireless communication environment, and adapt to changes in the wireless environment by adaptively adjusting its own internal communication parameters. Orthogonal Frequency Division Multiplexing (OFDM), which has the characteristics of anti-multipath and high frequency utilization, is a good platform for radio systems that are relatively easy to implement internationally.

After searching the existing literature, it is found that the Chinese patent application number is: CN201410801787, and the name is: A vehicle-mounted wifi network system based on the framework of the Internet of Vehicles, which relates to a vehicle-mounted wifi network system based on the framework of the Internet of Vehicles, which belongs to the vehicle-mounted wireless network field. However, the switching speed of wifi is relatively slow, which is not suitable for fast switching of in-vehicle networks. The Chinese patent application number is: CN201410759270, the name is: a data transmission device based on OFDM, which discloses a data transmission device based on OFDM, which uses high-speed DSP and corresponding software programming to monitor the operation of dual hosts and dual channels. Detection and judgment, but OFDM technology is not used in the field of Internet of Vehicles, nor does it recognize the signal. The above patents do not construct a vehicle networking system based on cognitive OFDM, nor propose an information transmission method based on a mobile ad hoc network, which has certain limitations. The disadvantages of the existing technology mainly include: 1) The vehicle-mounted wifi network system based on the Internet of Vehicles framework uses wifi as a communication method, and the switching delay is very long; 2) 4G network capacity is limited, and the amount of vehicle data released is large, The cellular network is difficult to load; 3) The 802.11p protocol does not perform dynamic spectrum sensing and switching, and cannot adapt well to a dynamically changing communication environment.

Therefore, those skilled in the art are committed to developing a V2I/V2V vehicle networking system and method based on cognitive OFDM, which can alleviate the pressure on the currently scarce cellular network resources, improve the network access speed compared with wifi, and Guarantee the real-time and reliability of data transmission.

Contents of the invention

In view of the problems existing in the prior art, the technical solution of the present invention aims at the first two shortcomings, and uses the ISM frequency band to use Orthogonal Frequency Division Multiplexing (OFDM), which has the characteristics of anti-multipath and high frequency utilization, and more importantly Yes, this method has a short handover delay and can effectively relieve the pressure on the 4G network after successful deployment. The mobile ad hoc network information transmission method continuously perceives changes in the wireless communication environment, and adapts to changes in the wireless environment by adaptively adjusting its own internal communication parameters, which can reduce the bit error rate and improve information throughput.

The invention fully considers the problems of noise, interference and fading faced by the wireless link, and ensures the communication between the vehicle-mounted unit and the surrounding vehicle-mounted units and roadside units. The invention also provides a mobile ad hoc network information transmission method, thereby ensuring real-time and reliability of data transmission.

In order to achieve the above purpose, the present invention provides an OFDM-based V2I/V2V vehicle networking system, including an on-board unit and a roadside unit, the on-board unit and the roadside unit are configured to use the ISM frequency band for wireless communication, transmission Video, voice, text data, and provide traffic safety information and traffic status information to drivers.

Further, the vehicle-mounted unit is configured to collect information around the vehicle, wirelessly transmit it to the surrounding roadside units or other vehicle-mounted units, and receive data transmitted from the surrounding roadside units or other vehicle-mounted units.

Further, the vehicle unit includes an information collection module, a communication module and a control host module, the information collection module includes a camera and a microphone, and the information collection module is configured to obtain video information and sound information; the communication module is configured In order to wirelessly transmit the video information collected by the camera and the sound information collected by the microphone to other vehicle-mounted units and roadside units; the control host module is configured to process the data of the collected information, and transmit the processed data to the communication module .

Further, the vehicle-mounted unit is configured to sense the quality of the wireless channel, so that the vehicle networking system works on the optimal carrier frequency and sub-carrier group.

Further, the roadside unit is configured to send information to the surrounding vehicle-mounted units and roadside units, and at the same time receive information transmitted from the surrounding vehicle-mounted units and roadside units; The real-time road condition information that unit uploads, and described information forwards to other roadside unit; Described roadside unit is configured to send real-time road condition, weather information to nearby vehicle-mounted unit; Described roadside unit is configured to The wireless communication quality can be monitored in real time, spectrum sensing can be performed, and the vehicle networking system can work on the optimal carrier frequency and sub-carrier group.

The present invention also provides a mobile ad hoc network information transmission method, comprising the following steps:

The first step is to provide vehicle-mounted units and roadside units, configure wireless communication parameters, and device numbers;

In the second step, the information collection module starts to collect video, sound, text and other information, controls the host module to compress, encode, package, and modulate, and sends the modulated information to the sending queue;

In the third step, the sending end notifies the receiving end on the control channel that data is about to be sent;

In the fourth step, the sender waits for the confirmation signal, and returns to the third step if there is no confirmation signal within the specified time;

In the fifth step, the receiving end performs spectrum sensing, and feeds back the carrier frequency and subcarrier group with better channel quality to the sending end through the control channel;

In the sixth step, the sending end sends a data packet of video, sound or text information on the specified carrier frequency and subcarrier group according to the feedback data from the receiving end;

In the seventh step, the receiving end receives the information of a data packet, demodulates and verifies, and obtains the verification information; records the number of consecutive packet loss, and decides whether to perform spectrum sensing according to the number of packet loss, so as to switch between OFDM carrier frequency and subcarrier group ;

Step 8: The transmitter receives the response information, demodulates the response information, and extracts the verification information and channel switching information respectively; or if the response information times out, record the number of consecutive timeouts to dynamically adjust the power;

In the ninth step, repeat the fifth step to the eighth step until the data transmission is completed.

Further, the wireless communication parameters include the number of OFDM channels and the corresponding carrier frequency, IQ speed, modulation and demodulation parameters, filter parameters, information data packet parameters, and response data packet parameters; the device number is configured as On-board units and roadside units are distinguished by different numbers.

Further, the specific steps of the seventh step are:

7.1. Verification information, the receiving end demodulates the received data packet, and performs CRC verification to generate verification information;

7.2. Channel switching information. If the control host finds a data packet demodulation error, it will record the accumulated error times. When the accumulated error times reach a certain threshold, it means that the channel interference is serious and channel switching must be performed; In perception, the carrier frequency is generated according to the minimum channel interference power access principle, and then the OFDM sub-carrier group is switched according to the energy of the sub-carrier group.

Further, the specific steps of the eighth step are:

8.1. According to the channel switching information, determine the carrier frequency and subcarrier group used in the next cycle;

8.2. According to the verification information, decide to send the next data packet or retransmit the previous data packet in the next cycle;

8.3. When the number of consecutive timeouts of response information reaches a certain threshold, which indicates that the link quality is degraded, the sending terminal increases power to improve communication quality, and the response information times out, retransmitting the last data packet.

The present invention also provides a mobile ad hoc network information transmission method, comprising the following steps:

The first step is to provide vehicle-mounted units and roadside units, configure wireless communication parameters, and device numbers;

In the second step, the information collection module starts to collect video, sound, text and other information, controls the host module to compress, encode, package, and modulate, and sends the modulated information to the sending queue;

In the third step, the sending end notifies the receiving end on the control channel that data is about to be sent;

In the fourth step, the sender waits for the confirmation signal, and returns to the third step if there is no confirmation signal within the specified time;

In the fifth step, the transmitting end performs spectrum sensing and informs the receiving end through the control channel;

The sixth step is to send a data packet of video, sound or text information on the specified carrier frequency and subcarrier group;

In the seventh step, the receiving end receives the information of a data packet, demodulates and verifies, and obtains the verification information; records the number of consecutive packet loss, and decides whether to perform spectrum sensing according to the number of packet loss, so as to switch between OFDM carrier frequency and subcarrier group ;

Step 8: The transmitter receives the response information, demodulates the response information, and extracts the verification information and channel switching information respectively; or if the response information times out, record the number of consecutive timeouts to dynamically adjust the power;

In the ninth step, repeat the fifth step to the eighth step until the data transmission is completed.

The present invention provides an OFDM-based V2I and V2V vehicle networking system, including an on-board unit (OBU) and a roadside unit (RSU). Provide information such as traffic safety and traffic conditions to drivers, as shown in Figure 1.

The vehicle-mounted unit collects information near the vehicle and wirelessly transmits it to the surrounding roadside units or vehicle-mounted units, and at the same time receives the data transmitted by them. The vehicle-mounted unit includes an information collection module, a communication module and a control host module. The information collection module includes hardware devices such as a camera and a microphone to obtain video information and sound information. The communication module is used to wirelessly transmit the video information collected by the camera and the sound information collected by the microphone to other on-board units and roadside units. The control host is mainly used to process the collected information data, and deliver the processed data to the communication module. The vehicle-mounted unit can perceive the quality of the wireless channel and make the system work on the best carrier frequency and sub-carrier group.

The roadside unit is used to send information to the surrounding on-board units and roadside units, and at the same time receive the information transmitted by them. The roadside unit can receive real-time road condition information uploaded by the vehicle-mounted unit in real time, and forward the information to other roadside units. The roadside unit can send real-time road conditions, weather and other information to nearby vehicle-mounted units. The roadside unit can monitor the quality of wireless communication at all times and perform spectrum sensing to make the system work on the best carrier frequency and subcarrier group.

As shown in Fig. 3, the present invention also provides an information transmission method of a mobile ad hoc network. The information transmission method of the mobile ad hoc network provided by the present invention can autonomously adjust OFDM carrier frequency and subcarrier group by autonomously sensing the signal-to-noise ratio of each subcarrier of OFDM, and by adopting the principle of lowest channel interference power access; through power control and relay forwarding Solve the problem of wireless signal fading; thus ensure the real-time and reliability of data transmission. Both the transmitting end and the receiving end may be vehicle-mounted units and roadside units.

The method includes the following steps:

In the first step, the vehicle-mounted unit and the roadside unit are configured with wireless communication parameters, device numbers, etc.

The wireless communication parameters mainly include the number of OFDM channels and the corresponding carrier frequency and IQ speed; in addition, there are modulation and demodulation parameters, filter parameters, information data packet parameters, response data packet parameters, etc. The equipment number refers to the on-board unit and the roadside unit distinguished by different numbers.

In the second step, the information collection module starts to collect video, sound, text and other information. The control host module performs compression, coding, encapsulation and modulation, and sends the modulated information to the sending queue.

In the third step, the sending end notifies the receiving end on the control channel that data will be sent soon.

In the fourth step, the sender waits for the confirmation signal, and returns to the third step if there is no confirmation signal within the specified time.

In the fifth step, the receiving end performs spectrum sensing, and feeds back the carrier frequency and subcarrier group with better channel quality to the sending end through the control channel.

In the sixth step, the sending end sends a data packet of video, sound or text information on the specified carrier frequency and subcarrier group according to the feedback data from the receiving end.

In the seventh step, the receiving end receives the information of a data packet, demodulates and verifies, and obtains the verification information; records the number of consecutive packet loss, and decides whether to perform spectrum sensing according to the number of packet loss, so as to switch between OFDM carrier frequency and subcarrier group .

7.1. Verification information, the receiving end demodulates the received data packet, and performs CRC verification to generate verification information.

7.2. Channel switching information. If the control host finds a data packet demodulation error, it will record the accumulated error times. When the accumulated error times reach a certain threshold, it means that the channel interference is serious and channel switching must be performed. The receiving end first performs energy sensing on each carrier frequency, generates the carrier frequency according to the lowest access principle of channel interference power, and then switches OFDM subcarrier groups according to the energy of the subcarrier group.

In the eighth step, the transmitter receives the response information, demodulates the response information, and extracts the verification information and channel switching information respectively; or the response information times out, records the number of consecutive timeouts, and dynamically adjusts the power. The specific steps are:

8.1. According to the channel switching information, determine the carrier frequency and subcarrier group used in the next cycle.

8.2. According to the verification information, decide to send the next data packet or retransmit the previous data packet in the next cycle.

8.3. When the number of consecutive timeouts of response information reaches a certain threshold, which indicates that the link quality is degraded, the sending terminal increases power to improve communication quality, and the response information times out, retransmitting the last data packet.

In the ninth step, repeat steps 5 to 8 until the data transmission is completed.

The advantage of the present invention is that, fully considering the problems of link instability, noise, interference, and topological structure change faced by the Internet of Vehicles, a V2I and V2V Internet of Vehicles system based on OFDM is designed, which can perform wireless communication in the ISM frequency band, Transmit video, voice, text and other information, and provide drivers with traffic safety and traffic conditions and other information. Reduce the pressure on the currently scarce cellular network resources, and improve the network access speed compared with wifi. At the same time, the self-organizing network information transmission method provided by the present invention can autonomously adjust the OFDM carrier frequency and subcarrier group by autonomously sensing the signal-to-noise ratio of each OFDM subcarrier; solve the problem of wireless signal fading through power control and relay forwarding; thereby ensuring data transmission real-time and reliability.

The idea, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of the present invention.

Description of drawings

Fig. 1 is a system block diagram of a preferred embodiment of the present invention;

Fig. 2 is a system connection diagram of a preferred embodiment of the present invention;

Fig. 3 is a flow chart of a method of a preferred embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing. This embodiment is carried out on the premise of the technical solution of the present invention, and the detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

As shown in Figure 2, in this real-time example, both vehicle-mounted units are equipped with vehicle-mounted wireless communication terminals. The terminals are equipped with USB cameras, microphones, and notebook computers. The roadside unit uses a processor and is equipped with a radio frequency transceiver board for video, Receiving and restoring display of voice and text messages.

The vehicle-mounted unit collects data while the vehicle is running, and transmits the data to a nearby vehicle-mounted unit, or uploads the data to the roadside unit. The vehicle-mounted unit includes an information collection module, a communication module and a control host module. The information collection module includes hardware devices such as a camera and a microphone to obtain video information and sound information. The communication module is used to wirelessly transmit the video information collected by the camera and the sound information collected by the microphone to other on-board units and roadside units. The control host is mainly used to process the collected information data, and deliver the processed data to the communication module. The vehicle-mounted unit can perceive the quality of the wireless channel and make the system work on the best carrier frequency and sub-carrier group.

The roadside unit adopts the roadside base station platform and is equipped with a radio frequency transceiver board, which is used to send information to the surrounding vehicle-mounted units and roadside units, and receive the information transmitted by them at the same time. The roadside unit can receive real-time road condition information uploaded by the vehicle-mounted unit in real time, and forward the information to other roadside units. The roadside unit can send real-time road conditions, weather and other information to nearby vehicle-mounted units. The roadside unit can monitor the quality of wireless communication at all times and perform spectrum sensing to make the system work on the best carrier frequency and subcarrier group.

As shown in the flowchart 3, the present invention also provides an information transmission method of a mobile ad hoc network. The information transmission method of the mobile ad hoc network provided by the present invention can autonomously adjust OFDM carrier frequency and subcarrier group by autonomously sensing the signal-to-noise ratio of each subcarrier of OFDM, and by adopting the principle of lowest channel interference power access; through power control and relay forwarding Solve the problem of wireless signal fading; thus ensure the real-time and reliability of data transmission. Both the transmitting end and the receiving end may be vehicle-mounted units and roadside units.

The information transmission method of the mobile ad hoc network includes the following steps:

In the first step, the vehicle-mounted unit and the roadside unit are configured with wireless communication parameters, device numbers, etc.

This embodiment configures 3 communication channels, the carrier frequency is 2.40GHz, 2.41GHz, 2.42GHz, the IQ speed is 2M, divided into 256 subcarriers, the transmission power is 0dbm, the OFDM modulation and demodulation method is adopted, the upsampling multiple is 8, and the shaping filter The device and the matched filter are root raised cosine filters, the roll-off coefficient is 0.5, and the filter length is 6.

In the second step, the information collection module starts to collect video, sound, text and other information. The control host module performs compression, coding, encapsulation and modulation, and sends the modulated information to the sending queue. In this example, the audio information is encoded with 8 bits; the video is compressed with DCT transformation, adaptively encoded, and encapsulated according to the data packet format. The information bit is 4096 bits. After compression, one frame of image needs 4-8 data packets for transmission.

In the third step, the sending end notifies the receiving end on the control channel that data will be sent soon. The control channel in the example is 2.38G. In the example, it is assumed that the control channel will not be disturbed and occupied for a long time.

In the fourth step, the sender waits for the confirmation signal, and returns to the third step if there is no confirmation signal within the specified time.

In the fifth step, the receiving end performs spectrum sensing, and feeds back the carrier frequency and subcarrier group with better channel quality to the sending end through the control channel. The example first detects the occupancy of the three carrier centers of 2.40GHz, 2.41GHz, and 2.42GHz, selects the OFDM carrier, and divides the 256 subcarriers of 2M bandwidth into 4 segments, the system detects the occupancy of the 4 subcarrier groups, and selects no occupancy subcarrier groups for data transmission.

In the sixth step, the sending end sends a data packet of video, sound or text information on the specified carrier frequency and subcarrier group according to the feedback data from the receiving end.

In the seventh step, the receiving end receives the information of a data packet, demodulates and verifies, and obtains the verification information; records the number of consecutive packet loss, and decides whether to perform spectrum sensing according to the number of packet loss, so as to switch between OFDM carrier frequency and subcarrier group .

7.1. Verification information, the receiving end demodulates the received data packet, and performs CRC verification to generate verification information. In this embodiment, the check information indicates whether the check is correct or not by 1 bit according to the CRC check result.

7.2. Channel switching information. If the control host finds a data packet demodulation error, it will record the accumulated error times. When the accumulated error times reach a certain threshold, it means that the channel interference is serious and channel switching must be performed. The channel switching information has 5 bits in total, 1 bit indicates whether to perform channel switching, 2 bits indicate the target carrier frequency of switching, and 2 bits indicate the target subcarrier group of switching. The present invention can flexibly configure the bit number of channel switching information to realize multi-channel support. The control center receives the data packet for verification, and records the cumulative number of errors. When the cumulative number of errors reaches 8 times, the receiving end senses the center frequencies of the three OFDM carriers, finds the channel with the lowest energy, and then senses the four subcarrier groups. If it is decided to access 2.41GHz, subcarrier group 3, the channel switching information code is 10111, the receiving end immediately switches channels, notifies the sending end through the control channel, and waits for the signal from the sending end.

In the eighth step, the transmitter receives the response information, demodulates the response information, and extracts the verification information and channel switching information respectively; or the response information times out, records the number of consecutive timeouts, and dynamically adjusts the power. The specific steps are:

8.1. According to the channel switching information, determine the carrier frequency and subcarrier group used in the next cycle.

8.2. According to the verification information, decide to send the next data packet or retransmit the previous data packet in the next cycle.

8.3. When the number of consecutive timeouts of response information reaches a certain threshold, which indicates that the link quality is degraded, the sending terminal increases power to improve communication quality, and the response information times out, retransmitting the last data packet.

In the ninth step, repeat steps 5 to 8 until the data transmission is completed.

In addition, in the fifth step of the information transmission method of the mobile ad hoc network described in the present invention, the receiving end performs spectrum sensing, and feeds back the carrier frequency and subcarrier group with better channel quality to the sending end through the control channel; and Six steps, the sending end sends a data packet of video, sound or text information on the specified carrier frequency and subcarrier group according to the feedback data from the receiving end; Tell the receiving end to send a data packet of video, sound or text information on the specified carrier frequency and subcarrier group.

The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection defined by the claims.

Claims (7)

1. An OFDM-based V2I/V2V vehicle networking system, characterized in that it includes a vehicle-mounted unit and a roadside unit, the vehicle-mounted unit and the roadside unit are configured to use the ISM frequency band to perform wireless communication, transmit video, Voice or text data, and provide traffic safety information and traffic condition information to drivers; The vehicle-mounted unit is configured to collect information around the vehicle, wirelessly transmit it to the surrounding roadside units or other vehicle-mounted units, and receive data transmitted from the surrounding roadside units or other vehicle-mounted units; The vehicle-mounted unit is configured to perceive the quality of the wireless channel, so that the vehicle networking system works on the optimal carrier frequency and sub-carrier group; The IQ speed of the ISM frequency band is 2M. 2. The OFDM-based V2I/V2V vehicle networking system according to claim 1, wherein the vehicle-mounted unit includes an information collection module, a communication module and a control host module, and the information collection module includes a camera and a microphone, so The information collection module is configured to obtain video information and sound information; the communication module is configured to wirelessly transmit the video information collected by the camera and the sound information collected by the microphone to other vehicle-mounted units and roadside units; the control host module is It is configured to process the collected information and transmit the processed information to the communication module. 3. The OFDM-based V2I/V2V vehicle networking system according to claim 1, wherein the roadside unit is configured to send information to surrounding vehicle-mounted units and roadside units, while receiving information from surrounding vehicle-mounted units and roadside units. The information transmitted by the roadside unit; the roadside unit is configured to receive the real-time road conditions uploaded by the vehicle-mounted unit in real time, and forwards the real-time road conditions to other roadside units; the roadside unit is configured to The above real-time road conditions and weather information are sent to nearby vehicle-mounted units; the roadside units are configured to be able to monitor wireless communication quality in real time and perform spectrum sensing, so that the vehicle networking system works on the best carrier frequency and sub-carrier group . 4. A mobile ad hoc network information transmission method, characterized in that it comprises the following steps: The first step is to provide the on-board unit and the roadside unit, configure the wireless communication parameters, and the device number, where the on-board unit and the roadside unit are used as the sending end or the receiving end; In the second step, the sending end collects video, sound or text information, performs compression, encoding, encapsulation and modulation, and sends the modulated information to the sending queue; In the third step, the sending end notifies the receiving end on the control channel that data is about to be sent; In the fourth step, the sender waits for the confirmation signal, and returns to the third step if there is no confirmation signal within the specified time; In the fifth step, the transmitting end performs spectrum sensing and informs the receiving end through the control channel; The sixth step is to send a data packet of video, sound or text information on the specified carrier frequency and subcarrier group; In the seventh step, the receiving end receives the information of a data packet, demodulates and verifies, and obtains the verification information; records the number of consecutive packet loss, and decides whether to perform spectrum sensing according to the number of packet loss, so as to switch between OFDM carrier frequency and subcarrier group , get channel switching information; Step 8: The sender receives the response information, demodulates the response information, and extracts the verification information and channel switching information respectively; or if the response information times out, record the number of consecutive timeouts to dynamically adjust the power; In the ninth step, repeat the fifth step to the eighth step until the data transmission is completed. 5. mobile ad hoc network information transmission method according to claim 4, is characterized in that, described wireless communication parameter comprises the number of OFDM channel and corresponding carrier frequency, IQ speed, modulation and demodulation parameter, filter parameter , an information data packet parameter, and a response data packet parameter; the device number is used to distinguish the on-board unit and the roadside unit through different numbers. 6. The mobile ad hoc network information transmission method according to claim 4, characterized in that the seventh step is as follows: 7.1. The receiving end demodulates the received data packet, performs CRC check, and generates check information; 7.2. If the receiving end finds a data packet demodulation error, it will record the cumulative number of errors. When the cumulative error count reaches a certain threshold, it means that the channel interference is serious and channel switching must be performed; the receiving end first performs energy sensing on each carrier frequency, and according to the channel The minimum interference power access principle generates the carrier frequency, and then obtains channel switching information according to the energy of the subcarrier group, and switches the subcarrier group of OFDM. 7. The mobile ad hoc network information transmission method according to claim 4, characterized in that the eighth step is as follows: 8.1. According to the channel switching information, determine the carrier frequency and subcarrier group used in the next cycle; 8.2. According to the verification information, decide to send the next data packet or retransmit the previous data packet in the next cycle; 8.3. If the number of consecutive timeouts of response information reaches a certain threshold, which indicates that the link quality is degraded, the sending end will increase the power to improve the communication quality and retransmit the last data packet.