| With the rapid economic and social development,people’s pressure on traffic travel is also increasing.Contradictions such as traffic jams and barriers to road travel have become increasingly acute.Under such a background,in order to ease the pressure on the city’s traffic,the whole solution for the smart car networking system that facilitates the traffic of urban vehicles is born.This paper mainly studies theoretical analysis and actual hardware design of the baseband communication platform for vehicle networking based on the IEEE802.11 p protocol.It covers related technical principles,hardware design,FPGA implementation,simulation analysis,on-line testing,and final analysis of results.,Compared with the system completely reproduces the whole process of the design,development and implementation of the car networking baseband communication system.The main contents are as follows:First of all,the introduction of the overall architecture of the car networking system is divided into two major blocks,namely the communication cloud platform network and the car networking platform.After that,it focuses on introducing the core of the architecture of the entire car network,ie the OBU(vehicle intelligent terminal)and RSU(roadside intelligent terminal)in the car networking platform.The schematic diagram of the principle of information exchange between the two is given and the initial guidance is given.Secondly,the protocol to be followed and the key technologies adopted for bringing forward the baseband communication in the Vehicular Physical Layer are established,ie IEEE802.11 p protocol and OFDM modulation technology.The IEEE802.11 p protocol specifically introduces the development history,channel and transmit power environment,physical layer frame structure,key parameters,and the lateral comparison with the IEEE802.11 a protocol,etc.,and a relatively complete interpretation of the protocol.OFDM modulation technology is an in-depth analysis of technical development,technical principles,advantages and disadvantages,and modulation implementation architecture.Combined with the analysis of the physical layer frame structure and understanding of the modulation method,the hardware design of the baseband transceiver is further guided.After that,it is the core content of this article,that is,the overall hardware designand FPGA implementation of the baseband communication of the car network.Divided into two major modules,transmitter and receiver parts.The main processing flow of the transmitter includes scrambling,convolutional coding,interleaving,modulation,insertion of pilots,IFFT,and addition of cyclic prefix.The receiver mainly includes frame synchronization,symbol synchronization,carrier synchronization,residual phase synchronization,and channel estimation.With equalization,demodulation,deinterleaving,Viterbi decoding,descrambling modules,etc.[2].Each module starts from the operation mechanism,from the principle analysis,to the hardware block diagram design,code implementation,and finally gives the Modelsim simulation waveform diagram.It should be noted that due to the frame structure,in the transmitter module,the data in the Signal field and the Data field must be treated differently.Finally,on-board on-board testing of transmitter and receiver hardware designs,on-chip observations using ChipScope Pro,and comparison of Modelsim simulation charts were used to compare the results. |
