978-1-4673-4404-3/12/$31.00 ©2012 IEEE Energy Saving by Base Station Pooling: A Signaling Framework Malla Reddy Sama, Ashish Gupta, Hossam Afifi, Marc Girod Genet, Badii Jouaber CNRS SAMOVAR UMR 5157, Telecom SudParis, Evry, France Emails: {sama.malla reddy, ashish.gupta, hossam.afifi, marc.girod genet, badii.jouaber}@telecom-sudparis.eu Abstract—Energy consumption is among the major problems faced by cellular operators. In metropolitan areas, cellular net- work is divided into smaller cells due to high traffic. During low traffic period e.g., at midnight, Base Stations are underutilized but remain active and consume energy. In this paper, we propose two signaling frameworks for pooling the Base Stations of different cellular operators in a single cell during low traffic. The first Framework can be deployed rapidly with existing infrastructure. While the second framework can be used with Base Stations with enhanced capabilities. We consider cellular network with real Base Stations location in Paris region. We have taken blocking probability as Quality of Service parameter. Proposed signaling frameworks take into account call processing, subscribers soft handover between different operator’s Base Station. In this way, up to 66% energy saving can be achieved for three different service providers in a single cell at low traffic period which also helps in the reduction of cellular radiation. Index Terms—Base Station pooling, blocking probability, en- ergy saving, signaling framework, cellular system. I. I NTRODUCTION The use of ICT (Information and Communication Technol- ogy) should be made more efficient to reduce energy con- sumption and radiation. Most of the telecom operators have set energy savings as one of the evaluation parameter for their new wired and wireless infrastructure. At the same time the price of electricity has been increasing [1] and negatively impacting the operational costs of telecom companies. Therefore, reducing energy consumption has economic benefit as the wireless network operators are estimated to spend more than 10 billion dollars for electricity [2]. Recently, there has been focus on energy-efficiency in wireless networks from the perspective of reducing the potential harms to the environment caused by electromagnetic radiation [3]. In this paper, we have taken real Base Station (BS) locations of cellular networks in the Paris region via Opensignalmap [4], since these are the main energy consumers in cellular networks. Even BSs with very less activity or noactivity consumes up to 90% of their peak energy [3]. When BS of one operator is switched-off, radio coverage and services are taken care of by the other operator which remains active. The switching-off mechanism of BS must be carefully decided among operators, so as to maintain the desired quality of service (QoS) and meet radiation coverage constraints. This paper proposes two signaling frameworks which allow BSs operated by different operators to switch-on/off depending on the traffic load experiences by each of the BS (Node B). With our frameworks, the “Billing Cycle” remains intact for each of the operator as we are pooling only the Base Stations but MSCs (Mobile Switching Center) and RNCs (Radio Network Controller) remain active. The frameworks do not need to change any existing infrastructure. Further, our proposed signaling frameworks are within the existing 3GPP standards. This paper is organized as follows. Section II presents the Motivation for this work and related work. Section III presents framework designs. Section IV does analysis and finally Section V concludes the paper. II. MOTIVATION Mobile user density is very high in metropolitan areas. Due to high traffic the region is divided into smaller cells. However, the cellular network experiences redundancy during very low traffic hours. Fig. 1 shows real location of Base Stations in Paris region. The highlighted region has approximately 20 BSs of two Operators (Blue is Orange and Green is Bouygues Telecom). Fig. 1. Two operator’s Base Stations in highlighted region in Paris [4] Fig. 2 shows the overlapping radiation pattern of two operators’ BSs. The Fig. 3 shows cellular network if BSs of Bouygues Telecom are switched-off and cellular services are provided by single operator (Orange) in the highlighted region. Fig. 4 shows the radiation of one operator (Orange). Even after switching-off one operator’s BS, we can still cover the highlighted region. In this way we can guarantee the coverage. The user does not get any problem with signal. Hence, we can save power and decreases the radiation footprint up to 40 - 50% during low traffic. Therefore, if different operators pool their BSs, there can be significant energy savings by switching-off some BS in the network.