An Optimal Roadside Unit Placement Method for VANET Localization

This paper presents an optimal roadside unit (RSU) placement method for vehicle localization in Vehicle Ad-hoc Networks (VANETs). Since the RSU layout can significantly affect the performance of localization algorithms, the proposed method needs to find an optimal K-coverage RSU placement, to ensure the best localization accuracy while using minimum number of RSUs. We adopt the Geometric Dilution of Precision (GDOP) metric to evaluate the accuracy provided by RSU placements, and derive the expression of GDOP towards received signal strength (RSS) and hybrid parameter estimators, respectively. There are two steps contained in the proposed method. Firstly, the optimal elementary pattern is obtained and applied to form the 1-coverage placement. Secondly, the optimal K-coverage placement based on K-layer elementary patterns is found by minimizing the average GDOP of the road area, using asynchronous particle swarm optimization (APSO) algorithm. In simulations the convergence and stability of APSO solutions are verified, then our method is compared with existing uniform placement method, the results show that the proposed method can achieve better positioning performance.