Mitigating climate change and its impacts is one of the sustainable development goals (SDGs) required by United Nations for an urgent action. Increasing carbon emissions due to human activities is the root cause to climate change. Telecommunication networks that provide service connectivity to mobile users contribute great amount of carbon emissions by consuming lots of non-renewable energy sources. Beyond the improvement on energy efficiency, to reduce the carbon footprint, telecom operators are increasing their adoption of renewable energy (e.g., wind power). The high variability of renewable energy in time and location; however, creates difficulties for operators when utilizing renewables for the reduction of carbon emissions. In this paper, we consider a heterogeneous network consisted of one macro base station (MBS) and multiple small base stations (SBSs) where each base station (BS) is powered by both of renewable and non-renewable energy. Different from the prior works that target on the total power consumption, we propose a novel scheme to minimize the carbon footprint of networks by dynamically switching the ON/OFF modes of SBSs and adjusting the association between users and BSs to access renewables as much as possible. Our numerical analysis shows that the proposed scheme significantly reduces up to 86% of the nonrenewable energy consumption compared to two representative baselines.

翻译：减缓气候变化及其影响是联合国要求的可持续发展目标之一，亟需采取行动。人类活动导致的碳排放增加是气候变化的根源。为移动用户提供连接服务的电信网络因消耗大量不可再生能源而产生大量碳排放。除提升能源效率外，为减少碳足迹，电信运营商正逐步增加可再生能源（如风能）的使用。然而，可再生能源在时间和空间上的高度不稳定性，给运营商利用可再生能源减排带来困难。本文考虑由一台宏基站和多台小基站组成的异构网络，每台基站同时由可再生能源和不可再生能源供电。与以往以总功耗为目标的研究不同，我们提出一种新方案，通过动态切换小基站的开关模式并调整用户与基站的关联关系，以最大化利用可再生能源，从而最小化网络碳足迹。数值分析表明，与两种代表性基线方案相比，该方案可将不可再生能源消耗显著降低高达86%。