Combining Capital and Operating Expenditure Costs in Vehicular Roadside Unit Placement

This paper considers the problem of vehicular roadside unit (RSU) placement so that the sum of capital expenditure (CAPEX) and operating expenditure (OPEX) costs is minimized. The minimum cost solution considers these two cost contributions jointly when making RSU placement decisions. The input to the placement process consists of historical vehicular traffic traces and a set of candidate site locations from which RSU placements are chosen. An integer linear program (ILP) formulation is first given that computes the minimum cost placement based on the input traffic traces and candidate locations. A practical algorithm is then introduced that solves a relaxed version of the ILP and uses a novel rounding procedure to obtain real RSU placements. The algorithm takes into account the energy costs incurred by vehicular requests when the latter are scheduled using a minimum energy online scheduler. Performance results are presented that show that the proposed algorithm performs well compared to the case where placements are done without jointly considering both CAPEX and OPEX cost components.