Thursday, 25 April 2019

In home base stations reduce mobile phone radiation exposure

FemtocellInstall a tiny base station – or femtocell – in your home and, contrary to many people’s initial feelings, you will reduce your exposure to mobile phone radiation an Irish study has found.

“Contrary to many individuals’ initial feeling that putting a base station in your home would increase exposure, these findings indicate that having a femtocell in the home will often reduce the mobile handset user’s exposure to radiofrequency energy, ” researchers Brad Zarikoff and David Malone at the National University of Ireland said.
Traditional cellular network construction relies on using a single base station to cover a large area and serve dozens to hundreds of users. Whereas the femtocell – named after the minuscule size of the coverage area – provides a low power, in-home cellular connection for the mobile handset, Zarikoff and Malone explain in their paper recently published in the scientific journal Health Physics.
The main purpose of installing a low power femtocell in a home or office is to give the user a strong “5-bar” signal and better coverage within office buildings but their research showed that it also reduced users exposure to mobile phone radiation due to a little known feature of mobile technologies – adaptive power control. To be more environmentally friendly, improve battery capacity and reduce interference, mobile phones and network base stations reduce power output to the minimum level required to make a quality connection.
The researchers compared the exposure of the mobile phone user using 3G technologies in a home with and without the presence of a femtocell, at 1, 2, 3, 4, 5, 10, and 15 metres away.
They then calculated a user’s exposure when making an average length mobile phone call of 3.29 minutes and with and without the femtocell operating. They also looked at the impact of making 5 of these average length calls over a 24 hour period with and without the femtocell.
“For a single call of 3.29 min with a femtocell present, the contribution of the femtocell is greater than that of the phone when the distance between them is less than 3 m. Beyond 3 m, the exposure from the phone is greater than that from the femtocell,” Zarikoff and Malone said. “In this example, the macrocell contribution is ‘dwarfed’ by both the phone and femtocell exposures.”
However, without the femtocell the exposure from the phone increases significantly.
“In terms of the RF exposure, it is clear from the simulations that the maximum incident power or RF exposure is less in the case of the femtocell [FBS], primarily because of the smaller distance from the handset when compared to the macrocell,” Zarikoff and Malone said.
The researchers suggest owners of a small house could install a femtocell and reduce their exposure by a factor of 150, and the owners of a larger house reduce their exposure by a factor of 6 after installing a femtocell.
“This model is a combination of accepted empirical channel models and the standardized power control mechanism used in commonplace cellular devices, which was explored via experimental results. In general, the current results demonstrate that only in cases of excessive distance between the mobile user and the femtocell will the user experience more exposure then if connected to the macrocell,” Zarikoff and Malone concluded.
For more information about femtocells see EMFexplained.
What are femtocells

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