Resource Optimization For C-V2X And MmWave Radar In Vehicular Networks

Vehicular communication and automotive radar sensing technology is promising for realizing intelligent,faster,safer transportation.The rapidly increasing amount and mobility of vehicles require frequent resource allocation,which can cause network congestion,large signalling and processing delay.In addition,due to the limited available bandwidth,wide deployment of radar sensors on automotive vehicles can potentially lead to a severe interference problem.Therefore,resource optimization for vehicular communication and automotive radars becomes a key issue in future autonomous vehicular networks,to meet their performance requirements and improve the spectral efficiency.In this thesis,we investigate the resource optimization algorithm for vehicular communications and automotive radars in vehicular networks.Our work not only propose a resource allocation scheme that can effectively reduce delay and improve spectral efficiency and a mode selection scheme to reduce energy consumption for vehicle communication,but also propose a power optimization scheme based on interference analysis for automotive radar sensing system.The specific contributions and achievements can be summarized as follows:Regarding resource allocation and optimization scheme for vehicular communications,we propose a novel semi-persistent resource allocation scheme based on a two-tier heterogeneous network architecture including a central MBS and multiple RSU.Considering the predictability of vehicular flows,we combine the traffic prediction with this resource allocation scheme.In the proposed semi-persistent scheme,the MBS pre-allocates persistent resources to RSUs based on predicted traffic,and then allocates dynamic resources upon real-time requests from RSUs while vehicles simultaneously communicate using the preallocated resources.Based on this scheme,we mainly study two classes of optimization problems for two scenarios of expressway and urban cross section:1)minimizing the relative latency with the constraint of total bandwidth;2)minimizing the total bandwidth with the constraint of transmission latency.Different algorithms are developed to address the problems.For the first problems,a simple ST-kNN method is developed for short-term traffic prediction,and a geometric water-filling algorithm is developed for minimizing the relative latency.For the second optimization problems,we use LMMSE for traffic prediction and provide an optimal solution to the problem.Both simulation results validate the effectiveness of the proposed semi-persistent scheme in comparison with two benchmark schemes.Towards the mode selection scheme for V2X communications,we investigate a two-tier heterogeneous cellular network where the macro tier and small cell tier operate according to a dynamic TDD.Based on dynamic TDD which can adjust uplink and downlink time configurations to accommodate to the traffic asymmetry,we propose a V-D2D mode selection scheme jointing time aliocation,power control to minimize the energy consumption of the vehicles and the whole network.The problem is formulated as a convex optimization problem,and a geometrical interpretation is provided.Simulation results show that the energy consumption can be decreased effectively in V-D2D mode,and VD2D communication area accounts for a large part both in the macro cell and small cell.For the interference characterization of mmWave vehicular communication and automotive radars and research on power optimization of automotive radar,we firstly study the mean power of effective echo signals and interference,by considering both mmWave front-and side-mounted automotive radars equipped with directional antennas.We employ the stochastic geometry method to characterize the randomness of vehicular location and hence radars in both two-lane and multi-lane scenarios,and derive closed-form expressions for the mean interference by approximating the radiation pattern by Gaussian waveforms.Simulation results are shown to match the analytical results very well,and insights are obtained for the impact of radar parameters on interference.Then,using similar interference analysis methods and considering the characteristics of millimeter wave communication,we analyze the average interference of millimeter wave vehicle communication in single lane and two-lane scenarios,and obtain the influence characteristics of different antenna types on the average interference through simulation.Next,based on the interference analysis of automotive radars,we aim to minimize the total transmission power of each vehicle with constraints on the required signal to interference and noise ratio.An optimal solution is obtained based on linear programming techniques and corroborated by simulation results.