Research On Joint Power Control And Multiple Antennas Allocation Optimization Algorithm In Vehicular Ad Hoc Network

With the rapid development of science and technology in recent years,more and more vehicles on the road have brought many traffic problems.As an important part of intelligent transportation system,vehicle ad hoc network can effectively reduce traffic congestion and vehicle accidents.The dynamic topology of vehicle ad hoc networks has a significant impact on the transmission and reception of data.Due to the increase in the number of vehicles on the road and the rapid changes in network topology,hidden and exposed terminal problems can result,which in turn can cause receiver blockage.How to reduce the blocking of data transmission and improve the validity of data transmission is still a challenging problem.In this paper,considering allocating multiple antennas for each vehicle and selecting the appropriate power for the vehicle,a distributed joint power control and multiple antennas allocation optimization algorithm is proposed.On the basis of power control and multiple antennas,time slot allocation is introduced,and a joint power control and multiple antennas allocation optimization algorithm based on time slot allocation is proposed to select the best time slot for data packet transmission and realize all vehicles Collision-free transmission between messages.First,consider using different power levels for each vehicle and having multiple antennas for each vehicle at the same time.Then formulate a joint distributed power control with multiple antennas(DPC-MA)allocation optimization problem to increase throughput,which can minimize blocking.This problem judges the neighborhood relationship between vehicles based on vehicle distance and transmission power and establishes an optimization model to select the optimal transmission power and number of antennas,with the goal of maximizing throughput,so that as many vehicles as possible can simultaneously communication.The DPC-MA problem is an NP-hard mixed integer nonlinear programming problem(MINLP).In order to solve the DPC-MA problem,a vehicle selection scheme is firstly added according to the position and velocity between vehicles when the constraints are not always established.Then a low-complexity efficient algorithm using Lagrangian duality is proposed,which decomposes the original problem into a series of sub-problems and solves iteratively using the fixed-point iterative algorithm and the subgradient method.The algorithm has low complexity and only grows polynomially in the number of optimization variables.Second,considering allocating a time slot for each vehicle,and based on power control and multiple antennas,a joint power control with multiple antennas(TPC-MA)allocation optimization problem based on time slot allocation is formulated.It minimizes the number of slots consumed and increases network throughput to resolve congestion.This problem considers the time slot allocation matrix of vehicles,and multiple vehicles can be allocated the same time slot.In this paper,two optimization models are established,one of which allocates appropriate time slots for vehicles to solve the problem of minimizing the number of time slots,and the other optimization model selects the optimal transmit power and number of antennas for vehicles to solve the problem of maximizing throughput.With the goal of minimizing the number of time slots used,spatial multiplexing can be achieved to improve network transmission efficiency.Then,under the constraint that each vehicle can only use one time slot,the optimization problem is formulated as the maximization of throughput.Aiming at the proposed problem of minimizing the number of slots,the vehicle topology and the characteristics of the slot allocation matrix are used to solve the problem.In addition,the throughput maximization problem is decomposed into multiple sub-problems for iterative solution using hierarchical decomposition technology,and its convergence and complexity are analyzed.Finally,the joint power control and multiple antennas allocation optimization algorithm proposed in this paper,and the joint power control and multiple antennas allocation optimization algorithm based on time slot allocation are verified by using SUMO and MATLAB simulation software.Simulation results show that the algorithm proposed in this paper can effectively reduce data transmission conflicts and improve network throughput.At the same time,this paper summarizes the existing work content,expounds the current problems to be improved and unsolved,and the future research direction.