Research And Development Of Key Technologies For Broadband Wireless Ad Hoc Networks On Board/Under Vehicles

In recent years,great progress has been made in protocol design,hardware chip and communication technology,which makes it possible to design and deploy different types of networks in various environments.Ad Hoc network was originally used for military communication,and has developed to various fields.It effectively solves the real-time communication problem in complex network environment,and has been widely used in field communication,disaster prevention,emergency communication and environmental monitoring.Vehicle ad hoc network is one of the hot areas.Based on the project,aiming at achieving high-speed transmission under the access of multiple mixed transmission services,this paper studies the key technologies of vehicle wireless ad hoc network,including synchronization technology,multi-service access technology in MAC layer and error control technology in DLC layer,and designs and implements the protocol for high-speed access.Firstly,this paper introduces classical MAC access protocols,including competitive,fixed allocation and hybrid access protocols.Combining with the characteristics of vehicular network,the advantages and disadvantages of each protocol are described.Combined with the existing synchronization technology,the difficulty and synchronization effect are analyzed.This paper introduces the error control technology of DLC layer,including three ARQ protocols,and compares and summarizes their efficiency.Secondly,according to the needs of the project,this paper offers the overall protocol design framework.Time slot and synchronous design scheme which meet the performance requirements of this system are given.For requirements of multiple hybrid services in wireless networking,this paper offers the design implementation scheme of static allocation TDMA for synchronous services,dynamic reservation TDMA for voice services,and CSMA and CSMA/CA hybrid access for data transmission services.Then this paper introduces the details of the implementation process of the two main services,and offers the design implementation scheme of selecting retransmission ARQ in the error control design of the data transmission service.Finally,in the OMNET++ simulation software,the function of multi node and multi hop network topology is simulated to verify the program function,and the network throughput,node number and distributed inter frame gap are simulated and compared.On the high performance development platform of ZYNQ,functional verification of the designed and implemented protocol is carried out,and the use of oscilloscope,spectrum analyzer and other devices to communicate with voice and data transmission services is tested,and the correctness of the design is verified.Through simulation,hardware and software debugging,the feasibility of the design protocol is verified.Compared with the basic self-organizing network,high-speed access is achieved to meet the requirements of the project.