Cosmote

Everything you always wanted to know about mobile telephony

We are at your disposal to answer your questions as well as for any additional information. Just send us an email at emfinfo@cosmote.gr. You can also download to your PC the special COSMOTE leaflet “Learn how mobile telephony works” (content in Greek).

How mobile telephony works  In Greece, and other 218 countries in the world, mobile telephony is based on the GSM (Global System for Mobile Communications), DCS 1.800 (Digital Cellural System), and UMTS (Universal Mobile Telecommunication System) Systems, which operate in frequencies of 900, 1,800 and 2,100 MHz.

The GSM, DCS 1,800, and UMTS systems are cellular. What does this mean? The geographical area that they cover is divided into smaller areas (the so-called cells) which are determined by the base stations’ coverage areas. These stations are usually installed on building roof tops or other high points.

The amount of the cells and the size of the area that they cover depend on the area’s geography, the width of the frequencies and the amount of calls made, as well as the number of users in a specific area. For example, in under populated rural areas, few base stations are installed, having a range of a few kilometers. In urban areas, many base stations are installed, the range of which may sometimes not exceed a few hundred meters. Each time you make a call, the signal is transmitted through the network, to the nearest base station.

The mobile telephony system is designed so that very low power base stations are installed in the cities as well as very close to one another, so that each one covers a cell. The reason for this particular structure is the limited frequency range that is available for mobile telephony. The frequencies must be reused so that many subscribers can talk simultaneously.

In order to understand how limited these frequencies are and why there cannot be more “central” mobile telephony base stations, it is worth mentioning that if, i.e. we had installed only one main antenna that would “work” for the entire city of Athens, only 130 subscribers per operator would be in a position to talk simultaneously.

One or more mobile telephony base stations installed in the mountains cannot possibly provide full coverage and service to the subscribers in urban areas, contrary to the radio and television stations that have great power, are installed in the mountains and communication with the receivers is one-way.  

What most people usually do not know is that the more base stations installed the less their transmission power and as a result, the mobile telephones emit less power. On the contrary, less base stations mean a weaker signal and a greater electromagnetic radiation transmission from the mobile phones that try to “locate” the nearest base station.

Electromagnetic waves…also known as radiation

What’s in a word! Electromagnetic radiation is not only transmitted by base stations and mobile phones, but also by many natural and artificial sources, such as the sun, the lamps, blow dryers, the TV or sockets! All these, of course, emit different types of radiation.

Mobile telephony is based on the transmission of electromagnetic waves. These are known as Hertzian waves, which are also used to transmit radio and television programs. The Hertzian waves are non ionizing radiation, i.e. radiation that cannot cause the ionization of the molecules and the destruction of chemical bonds. According to measurements, the exposure of humans in electromagnetic fields from the electrical supplies in their houses is higher than the corresponding exposure due to mobile telephony base stations on a roof top of a neighboring building or on their own building.