Design Of Preamble Sequences And Preamble Detection Algorithm For Vehicular Ad Hoc Network

As one of the key technologies of Internet of Things (IOT), Mobile Ad Hoc Network has the advantages of fast and flexible deployment and high survivability due to its de-centralized, self-organized and distributed network architecture. These advantages broaden the applications of mobile communications system, especially in military field. Vehicular Ad Hoc Network (VANET) is a special subclass of Mobile Ad Hoc Network designed for inter-vehicle communications. The data transmission in VANET often works in burst mode due to its rapidly changing topology and bad wireless channel conditions. Therefore, quick and accurate packet (frame) detection and synchronization among VANET nodes is a challenging task. This issue is discussed in detail and a solution is proposed in this thesis. The main works of the thesis are as follows.Firstly, the research background and application scenarios of the thesis are introduced. A brief summary of IOT, Ad Hoc network and some synchronization technologies in digital communication systems is presented. Then, the meaning and design scheme of synchronization in VANET discussed in this thesis are further discussed.Secondly, the design of preamble sequence used for synchronization is discussed in detail, which includes the concept and function of preamble sequence,preamble frame format and the matching rules of preamble sequences. The principles and optimization goals of preamble sequence codebook design are proposed. In order to achieve these goals, Genetic Algorithm is used to obtain preamble sequence codebook.Thirdly, the preamble detection algorithm is developed. The models of channel and match filter are described and the performance specifications of the algorithm are defined. A "double-correlation-peak" detection algorithm is proposed to reduce the probability of error detection and false alarm. Then a detailed elaboration of the principle and flow of the algorithm is given. In addition, the mathematical model of adaptive threshold detection based on the power estimation of received signal is derived and analyzed in comparison to the fixed threshold detection.Finally, Matlab simulations of preamble sequence search and preamble detection are finished. Simulation parameters and results are given. Analysis of the simulation results shows that the proposed scheme in this thesis is effective and achieves the expected design targets.