A Generalized and Dynamic Framework for Solar-Powered Roadside Transmitter Unit Planning

Roadside Unit (RSU) planning is a key step for the development of a robust Intelligent Transportation System (ITS). Many factors, including traffic flow variation, energy consumption, and budgetary constraints, all affect the daily operation and performance of the ITS. Therefore, there is an urgent need to effectively incorporate all these factors in designing a planning program that addresses this complex and dynamic problem. In this paper, we propose a general RSU planning solution, where complex and dynamic parameters are investigated. The objective is to maximize the effective coverage area of the placed RSUs, given: i) a planning budget comprised of periodic operating expenses (OPEX) and capital expenditures (CAPEX), ii) the physical limitations of the transceivers, and iii) the potential use of renewable energy to offset the on-grid electricity cost. We formulate a Mixed-Integer Quadratically Constrained Programming (MIQCP) problem that can simultaneously determine the optimal placement and daily activation/deactivation schedules of each RSU, whether or not they have a solar panel attached, and their ranges during each period of time. We performed a sensitivity analysis over a realistic map, and results show that as the budget increases, no matter the CAPEX/OPEX, there is an increase in coverage efficiency with a diminishing-returns behavior, a positive correlation between maximum transmission power ratings on the RSUs and coverage efficiency, and a negative correlation between minimum required data transfer rate and coverage efficiency.