MEASUREMENTS FOR ASSESSING THE EXPOSURE FROM 3G FEMTOCELLS Achilles Boursianis, Pantelis Vanias and Theodoros Samaras* Radiocommunications Laboratory, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece *Corresponding author: theosama@auth.gr Received July 7 2011, revised September 6 2011, accepted September 14 2011 Femtocells are low-poweraccess points, which combine mobile and broadband technologies. The main operation of a femtocell is to function as a miniature base station unit in an indoor environment and to connect to the operator’s network through a broadband phone line or a coaxial cable line. This study provides the first experimental measurements and results in Greece for the assessment of exposure to a femtocell access point (FAP) indoors. Using a mobile handset with the appropriate soft- ware, power level measurements of the transmitted (Tx) and the received by the mobile handset signal were performed in two different and typical (home and office) environments. Moreover, radiofrequencyelectric field strength and frequency selective measurements with a radiation meter (SRM-3000) were carried out in the proximityof the FAP installation point. The cumu- lative distribution functions of the Tx powerat most cases (except one) show that in 90% of all points the powerof the mobile phone was lower by at least 7 dB during FAP operation. At a distance of ∼1 m from the FAP (in its main beam), power flux density measurements show that there is very little difference between the two situations (FAP ON and OFF). As a con- clusion, the use of femtocells indoors improves reception quality, reduces the Tx power of the user’s mobile terminal and results in an indiscernible increase of the electromagnetic field in front of the unit, at valuesthat are extremely low compared with reference levels of exposure guidelines. INTRODUCTION Femtocells that are currently being marketed by 3G mobile phone providers are low-power access points, which combine mobile and broadband technologies. The femtocell unit functions as a miniature base station in the home or the office and connects to the operator’s network through a broadband phone line (digital subscriber line) or a coaxial cable line. This results in improved coverage and capacity within the environment of the femtocell owner, who has the ability to control which subscribers can make use of the unit. The femtocell allows up to about four simultaneous calls/data sessions at any time. The output power of femtocells is typically ,0.1 W, a value similar to other home network equipment (e.g. wireless broadband routers). Informa Telecoms & Media (1) expects the femto- cell market to experience significant growth over the next few years, reaching just under 49 million femto- cell access points (FAPs) in the market by 2014 and 114 million mobile users accessing mobile networks through femtocells during that year. According to Juniper Research (2) , femtocell-based services used by 3G mobile subscribers will generate in excess of $9bn per annum by 2014. However, potential health effects from the deploy- ment of femtocells remain a marketing issue (3) , since many people perceive them as a mobile phone mast in the home. In this work, the authors present the first experimental results of exposure assessment of 3G femtocells in Greece. MATERIALS AND METHODS A FAP (UAP2105, Huawei Technologies Co., Shenzhen, P.R. China) (Figure 1) was installed at a height of 1.7 m above floor level, (i) in a typical office environment, on the fourth floor of a building in the Aristotle University of Thessaloniki (premises of the Radiocommunications Laboratory), and (ii) in a typical home environment in the city of Thessaloniki. According to the mobile provider, the unit operated in Universal Mobile Telecommunications System (UMTS) absolute radiofrequency (RF) channel number 10639, i.e. at 2127.8 MHz, and the scram- bling codes used were between 508 and 511. Two different types of in situ measurements were per- formed to assess the exposure from the 3G femtocell. The purpose of the first type of measurements was to establish the probability distribution (received power distributions, cumulative distribution func- tions, CDFs) of the test phone’s power level in the primary coverage area of the femtocell and compare this with the power levels in the absence of the fem- tocell. A mobile handset model N95 8 GB (Nokia, Espoo, Finland) with the appropriate software (NetMonitor) was used to record the received signal code power (RSCP) of the pilot channel (CPICH) # The Author 2011. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com Radiation Protection Dosimetry (2012), Vol. 150, No. 2, pp. 158–167 doi:10.1093/rpd/ncr398 Advance Access publication 13 October 2011 Downloaded from https://academic.oup.com/rpd/article/150/2/158/1604932 by Aristotle University of Thessaloniki user on 25 July 2022