Towards a deployment tool for wireless access networks with minimal power consumption Margot Deruyck, Emmeric Tanghe, Wout Joseph, Willem Vereecken, Mario Pickavet, Bart Dhoedt, and Luc Martens Ghent University - IBBT, Department of Information Technology (INTEC) Gaston Crommenlaan 8, Bus 201, 9050 Ghent, Belgium email: margot.deruyck@intec.ugent.be web: www.intec.ugent.be Abstract—The power consumption of wireless access networks will become an important issue in the coming years. In this paper, the power consumption of base stations for mobile WiMAX, HSPA, and LTE is modelled. This power consumption is related to the coverage of the base station. The considered technologies are compared according to their energy efficiency for different bit rates at a bandwidth of 5 MHz. For this particular case and based on the assumptions of parameters of the specifications, HSPA is the least energy-efficient technology. Until a bit rate of 11 Mbps LTE is the most energy-efficient while for higher bit rates mobile WiMAX performs the best. Furthermore the influence of MIMO is investigated. A decrease of about 80 % for mobile WiMAX and about 74 % for HSPA and LTE for the power consumption per covered area is found for a 4x4 MIMO system compared to a SISO system. The introduction of MIMO has thus a positive influence on the energy efficiency of the considered technologies. The power consumption and coverage model for base stations is then used to develop a prediction tool for power consumption in wireless access networks. Index Terms—base station, coverage, MIMO, power consump- tion, mobile WiMAX, HSPA, LTE I. I NTRODUCTION The global Information and Communication Technology (ICT) industry is an important and quickly growing contributor to CO 2 emissions and energy consumption. In 2007, the total footprint of the ICT sector was 830 Megatons CO 2 e which is about 2 % of global human emissions and equivalent to those of global aviation [1], [2]. Furthermore, the power consumption of ICT is approximately 4 % of the annual energy consumption and it is expected that this number will double within the next 10 to 15 years [3]. Within ICT it is shown that the radio access networks are a large contributor to CO 2 emissions [3], [4], [5]. The base stations are responsible for roughly two-thirds of the CO 2 emissions of these radio access networks [4]. NTT DoCoMo recently investigated the daily power consumption per cus- tomer [5]. They found a power consumption per customer of 0.83 Wh for a terminal and 120 Wh for the mobile network resulting in a consumption ratio of about 1:150 for terminal versus network. The power consumption of the terminals (powered by batteries and thus already optimized) is thus negligible with respect to the power consumption of the mobile network. Therefore, it is clear that one should focus on the base stations in the wireless access networks in order to reduce the power consumption. The purpose of this research is to model the power con- sumption of base stations of various wireless technologies. This power consumption is related to the coverage. Based on these characteristics, we can compare the energy efficiency of the technologies for different scenarios. Furthermore, the influence of MIMO (Multiple Input Multiple Output) is inves- tigated and a first version of a deployment tool for minimal power is proposed. The outline of the paper is as follows: in Section II we give a short overview of the considered technologies. In Section III the power consumption of a base station is modelled and related to the coverage. Section IV gives some results for the considered technologies obtained with the model from Section III. In Section V we give our final conclusions. II. TECHNOLOGIES The power consumption and energy efficiency of three wire- less technologies is investigated: mobile WiMAX (Worldwide Interoperability for Microwave Access), HSPA (High Speed Packet Access) and LTE (Long Term Evolution). Mobile WiMAX is a wireless technology for broadband communication based on the IEEE 802.16e interface [6] and is operating in the 2-6 GHz band which is developed for mobile wireless applications. It uses the novel SOFDMA (Scalable Orthogonal Frequency Division Multiple Access) technique which is derived from OFDMA (Orthogonal Fre- quency Division Multiple Access) and supports a wide range of bandwidths to flexibly address the need for various spectrum allocation and application requirements. HSPA is the successor of the widely deployed UMTS (Uni- versal Mobile Telecommunications System) and works in the 2.1 GHz band [7]. It allows networks based on UMTS to have higher data rates, and increased cell and user throughput and reduced delay. Furthermore, HSPA supports shared channel transmission. This means that the channelization codes and the transmission power in a cell are dynamically shared between users. LTE is the newest wireless broadband technology [8]. In December 2009, world’s first publicly available LTE-service was started in Scandinavia [9]. LTE is marketed as the fourth