Compliance

The network antennas and devices used for mobile communications are subject to compliance standards to ensure that they satisfy the relevant safety recommendations. This area of the GSMA program ensures that compliance standards maintain pace with technology evolution and provide a basis for more accurate dosimetry for safety recommendations. These studies have been co-funded with the MMF in two phases (P1 – 2005 to 2007 and P2 – 2008 to 2010) as a series of work packages (WP).

P1/WP1 and P2/WP3: Low-Power Devices Used Close to the Body

P1/WP1 and P2/WP3: Low-Power Devices Used Close to the Body This is a two phase study by ARC Seibersdorf research GmbH (Austria) and the University of South Carolina (USA) investigating the relationship between basic characteristics of wireless devices (transmitted power, bandwidth, frequency, antenna gain and distance to the body) and the basic restrictions of the safety recommendations. The first phase examined antennas up to 20 mm from the body and is now complete. It provided a scientific rationale for determining compliance of certain low power devices without the need for full SAR measurements. This proposal will now be considered by relevant standards committees. A second phase began in early 2008 and will examine the same characteristics for antennas more than 25 mm from the body.

P1/WP3: Analysis of Exposures Near Base Station Antennas

Prof. Revaz Zaridze at the Tbilisi State University (Georgia) used computational techniques to study conducted exposures from nearby base station antennas. One of the situations studied is for a simplified human model (‘mummy shape’) in a room with an antenna pointing towards the window. As the video shows the field level within the room varies with time due to reflection of the radio signals. In the real world the room would not have perfectly conducting walls and would have other items such as furniture that would further complicate the analysis.

P1/WP3: Assessment of Public Exposures from Wireless Networks

This study linked to the EUREKA project BASEXPO with the aim of developing scientifically sound and feasible procedures to assess exposure next to mobile communication base stations. The study was coordinated by ARCS (Austria) and included institutions from Sweden, Greece, France, Belgium, and Switzerland. The study is now complete and a number of papers have been published. It was found that exposures are typically very low, however, real environments can be complex and there is a need to adequately account for the range in sizes of people to ensure that compliance levels are adequately conservative.

P1/WP3: Assessment of Public Exposures from Wireless Networks

P1/WP4: Radiofrequency Exposure Metrics 1- 10 GHz

The Australian Centre for Radiofrequency Bioeffects Research (ACRBR) investigated whether the localised energy absorption (termed the specific absorption rate (SAR)) or the incident power flux density was a better RF safety exposure metric in the frequency range of 1-10 GHz based on the maximum tissue temperature rise. The research is now complete and the findings submitted for peer-reviewed publication.

P1/WP5: Virtual Family Models

The basis for both safety standards and biological experiments is accurate knowledge of radiofrequency exposures. The Foundation for Research on Information Technologies in Society (IT’IS – Switzerland) and the Food and Drug Administration Center for Devices and Radiological Health (USA) were tasked with developing four anatomical high-resolution models of an average man, an average woman and two children. These were derived from magnetic resonance imaging (MRI) scans of a 26-year-old female adult, a 34-year-old male adult, 11-year-old female child and a 6-year-old male child. All four models and a software tool for working with the images are available free of charge to the scientific community for research purposes only.

P2/WP1: Compliance of Advanced Base Station Antennas

One of the approaches to achieving higher data rates from wireless communication technologies is the use MIMO (multiple input, multiple output) antenna technologies, where multiple antennas are used at both the source (transmitter) and the destination (receiver). Swinburne University of Technology (Australia) is studying how these more complex antenna configurations can be assessed for compliance with safety recommendations.

P2/WP2: Review of Thermal Effects Literature

The only established health effects from radiofrequency exposures are related to temperature rises in exposed biological tissues. Researchers at Duke University Medical Center and Temple University Medical School have been commissioned to review the existing scientific literature on thresholds for thermal injury to a range of tissues. This will contribute to greater understanding of the safety margins in existing radiofrequency exposure standards and their future development.

P2/WP4: Thermal Parameters Database and Analysis

The Swinburne University of Technology (Australia) is compiling a database of thermal parameters for a range of biological tissues. This data will be used with information from P1WP4 to analyse the impact on RF exposure-related temperature rise in the frequency range 1 to 10 GHz of varying each parameter. They will also examine the effect of the shape of the averaging volume on the calculated temperature rise.

P2/WP5-6-7: Scientific Basis for Base Station Exposure Compliance Standards

An international consortium involving the IT’IS Foundation (Switzerland), Ghent University (Belgium), Helsinki University of Technology (Finland), France Telecom Research & Development (France), Hokkaido University (Japan), EM Software & Systems (South Africa), ARC (Austria) and the FDA (USA) conducted large-scale numerical evaluations of human body models exposed to radio signals from mobile communication base station antennas. This will assess the variability and uncertainties associated with different human anatomy and posture and assist the development of an IEC standard for compliance assessment of mobile communications base stations.

P2/WP8: Temperature Based Low-Power Device Assessment

The University of South Carolina (USA) and Tbilisi State University (Georgia) are working to develop a scientifically robust assessment for low power wireless transmitters based on temperature rise in a nearby person. The study will aim to relate the basic characteristics of a wireless device (frequency, bandwidth, antenna gain and distance to the person) to the maximum temperature or temperature rise in the person. When complete, this project will provide a basis for standards organizations or national regulatory agencies to develop practical rules for exempting devices from RF exposure assessment.

Associated Publications

SAR versus Sinc: What is the appropriate RF exposure metric in the range 1-10 GHz? Part I: Using planar body models, Anderson et al., Bioelectromagnetics, Published Online: 28 Apr 2010.

The Virtual Family – development of surface-based anatomical models of two adults and two children for dosimetric simulations, Christ et al., Physics in Medicine & Biology, 55(2):N23-N38 21 January 2010.

Temperature rise in an anatomical human head model due to 2.45 and 3.7 GHz inverted-F antennas, Islam et al., 2011 IEEE International Symposium on Antennas and Propagation (APSURSI), 117-119, 3-8 July 2011.

A comprehensive tissue properties database provided for the thermal assessment of a human at rest, McIntosh et al., Biophysical Reviews and Letters, 5(3):129-151, September 2010.

SAR versus VAR, and the size and shape that provide the most appropriate RF exposure metric in the range of 0.5–6 GHz, McIntosh et al., Bioelectromagnetics, Published online: 12 January 2011.

SAR versus Sinc: What is the appropriate RF exposure metric in the range 1-10 GHz? Part II: Using complex human body models, 32(4):312-321, May 2011.

The relation between the specific absorption rate and electromagnetic field intensity for heterogeneous exposure conditions at mobile communications frequencies, Neubauer et al., Bioelectromagnetics, 30(8):651-662, December 2009.

EM Field Distribution Amd Propagation In Some Realistic Scenarios, Kakulia et al., Journal of Applied Electromagnetism, 9(2):39-53, December 2007.

Assessment of induced radio-frequency electromagnetic fields in various anatomical human body models, Kühn et al., Physics in Medicine & Biology, 55(4):875-890, 21 February 2009.

Correlating Threshold Power With Free-Space Bandwidth for Low-Directivity Antennas, Sayem et al., IEEE Transactions on Electromagnetic Compatibility, 51(1):25-37, February 2009.

SAR variation study from 300 to 5000 MHz for 15 voxel models including different postures, Uusitupa et al., Physics in Medicine and Biology, 55(4):1157-1176, 21 February 2010.

Statistical Multipath Exposure Of A Human In A Realistic Electromagnetic Environment, Vermeeren, Health Physics, 94(4):345-354, April 2008.

Whole-body SAR in spheroidal adult and child phantoms in realistic exposure environment, Vermeeren et al., Electronics Letters, 44(13):790-791, June 19 2008.

The influence of the reflective environment on the absorption of a human male exposed to representative base station antennas from 300 MHz to 5 GHz, Vermeeren et al., Physics in Medicine and Biology, 55(18):5541, 21 September 2010.