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：减轻气候变化及其影响是联合国紧急行动所要求的可持续发展目标之一; 增加人类活动造成的碳排放是气候变化的根源; 向移动用户提供服务连接的电信网络通过消耗大量不可再生的能源,为移动用户提供大量碳排放; 除了提高能源效率,为减少碳足迹,电信运营商正在更多地采用可再生能源(如风能); 可再生能源在时间和地点上的高度变异性;然而,在利用可再生能源减少碳排放时,给操作者造成困难; 在本文中,我们认为一个混合网络由一个宏观基地站和多个小型基地站组成,每个基地站均由可再生能源和非可再生能源提供电力,每个基地站均由可再生能源和不可再生能源提供电力; 除了提高能源效率以外,电信运营商正在增加采用可再生能源(如风能发电); 可再生能源在时间和地点上的高度变异性; 然而,可再生能源在利用可再生能源减少碳排放方面给操作者造成困难; 在本文件中,我们认为一个混合网络包括一个宏观基地站和多个小型基地站(SBSBS),每个基地站均由可再生和不可再生的能源提供电力; 我们的数字分析显示,拟议的计划大大降低了不可再生消费的基线。</s>