Energy Efficient Evolution of Mobile Broadband Networks

Over the last decade, the mobile communications industry has broken through some remarkable barriers, pushing further and transforming the way people communicate and access information. As the volume of traffic carried by mobile networks maintains an insatiable growth, mobile network operators are required to ensure that networks can scale accordingly. In addition to upgrading existing networks, a number of operators have already started to rollout a further radio access technology layer, Long Term Evolution, or LTE. In addition to enhancing network capacity, operators are also required to adhere to public commitments for reducing their energy and carbon footprint. In 2008 Vodafone stated that by the year 2020, efforts for reducing emissions are expected to halve emissions registered in the year 2006/7. In addition to presenting a more environmentally conscious brand, this is also hoped to reduce costs, which, based on increasing energy prices and necessary network upgrades are likely to increase. Since base station sites make up for about 75% of the power consumption in mobile networks, studies are focused on this specific network element. A number of factors believed to play a role in the power consumption of mobile networks are separately investigated and later combined, providing a realistic indication of how the consumption is expected to evolve. This is also used as an indication to determine how likely it is for operators to achieve power consumption and emission targets. In order for mobile network operators to upgrade existing infrastructure different options are available. Irrespective of the selected option, capacity upgrades are bound to increase the power consumption of the network. Carried through case studies, a first analysis compares a number of network evolution strategies, determining which provides the necessary performance while limiting the increase in power consumption. Overall, it is noted that a hybrid solution involving the upgrade of existing macro base station sites together with the deployment of outdoor or indoor small cells (heterogeneous network) provide the best compromise between performance and power consumption. Focusing on one of the case studies, it is noted that the upgrade of both HSPA and LTE network layers results in the power consumption of the network increasing by a factor of 4. When coupled with the growth in capacity introduced by the various upgrades (x50), the efficiency of the network is still greatly improved. Over the evolution period, the stated increase in power consumption does not consider improvement in base station equipment. By considering a number of different equipment versions, the evolution study is further extended to also include the