TDMA-Based MAC (CVTMAC) in Green Vehicular Networks

The growing need to reduce the carbon footprint and the operation expenditure (OPEX) in communication networks necessitates the deployment of wind powered base stations (BSs) and roadside units (RSUs) for vehicular communication networks in windy countries with limited solar irradiation. This system finds ready application in sparse areas like countryside and motorways that lack the supply from the national grid for economic reasons. The stringent performance requirement of vehicular communication systems owed to their critical services poses challenges to their greening efforts. In this paper, we design a robust time-division multiple access (TDMA) based MAC for an infrastructure based green vehicular network in a motorway scenario and investigate the network performance against the stringent quality of service (QoS) thresholds. We call the proposed Centralised Vehicular TDMA based MAC as CVTMAC for short. To obtain a realistic performance evaluation, we model and simulate the proposed MAC protocol with the real channel characteristics of the motorway environment fully incorporated. The off grid RSU is powered solely by an economical and easy to deploy small standalone wind energy conversion systems (SSWECS). Wind energy-based rate adaptation is deployed in the RSU to enhance the efficient utilization of available energy (considering the intermittent nature of wind energy). In this study the real vehicular traffic profiles and wind data for a specified motorway region have been utilised. Both analytic and simulation results reveal that with the introduction of small battery capacity (27 Ah), the green vehicular network is able to support QoS for data, audio and video-related applications at each hour of the day in a motorway vehicular environment.