Sleep mode effectiveness in cellular networks

Delia Ciullo

Politecnico di Torino


In this work we face the issue of energy consumption in cellular networks, with reference to the UMTS technology. In particular, we consider the access segment, since the vast majority (60 to 80%) of the energy that is consumed in a cellular network is due to Base Stations (BSs). We study BS sleep modes, which are today considered a viable approach to improve the energy efficiency of cellular access networks, by reducing power consumption in periods of low traffic. When some base stations are switched off, radio coverage and service provisioning are taken care of by the BSs that remain active, so as to guarantee that service is available over the whole area at all times. We develop simple analytical models that allow optimal BS switch-off times to be identified as a function of the daily traffic pattern, in the cases in which either just one switch-off per day is possible, or several switch-offs per day are permitted. We first assume that any fraction of base stations can be switched off, then we account for the constraints resulting from typical regular BS layouts, and we finally consider a real case. We quantify the percentage of energy which can be saved with BS sleep modes, proving that it can be close to 50% of the total network energy consumption. Moreover, we analyze the BS sleep and wake-up transients, investigating the amount of time necessary to implement the switch-off, while allowing terminals to handover to a new BS without overloading the signaling channels, and we show that the switch-off/on durations have a marginal impact on the energy savings achievable with the sleep mode scheme. Short Bio: Delia Ciullo received the Master degree in Telecommunication Engineering and the Ph.D. degree in Electronics and Communications Engineering, both from Politecnico di Torino in 2007 and 2011, respectively. In 2009, she has been a visiting student at the CNRG group of MIT, under the supervision of Prof. Eytan Modiano. She is currently a post-doc at Politecnico di Torino. Her research interests are in the fields of energy-aware networks, scaling properties in wireless networks, and P2P systems. Delia will be an ERCIM postdoctoral researcher in MAESTRO starting in April 2012.

[Delia Ciullo]
[Politecnico di Torino]