GSM: The radio station

( Part of Henrik Kaare Poulsen's GSM pages )

The radio station consists of

• One or more antennas
• A cabinet with electronic equipment

In some cases, the radio station has just one antenna. In other cases, more antennas are used. A common set-up is using 3 antennas. Each antenna is pointing in one direction. This means that the number of radio stations can be reduced. Each antenna covers one "sector" of the environment, hence replacing one station in each of the three directions. It is not possible to divide into more than 3 sectors, as the radio signals from the antennas are overlapping.

In order to connect the radio station to the network, some kind of transmission is necessary. In some cases a cobber or fibre wire in the ground is used, and in other cases a microwave antenna connecting the radio station to a neighbouring radio station is used.

The electronics cabinet is the heart of the station. The most important content is a number of radios. As explained before, each radio station can communicate on different frequencies. Each frequency has its own radio in the station. Each radio is capable of handling up to 8 telephone calls. In many ways the radio is equivalent to a mobile phone. However, the cellular phone is designed to be as small as possible, and to use as little power as possible. The radio station is cabable of transmitting with a lot more power than the mobile phone, and to correctly receive signals that are much weaker than the cellular phone can. The drawback is, that the radio station takes up much more space and uses much more power.

Some radio stations integrate the electronics cabinet and the antennas. Such systems can be mounted outdoor on a mast, with no need for an equipment room. As an example, the NOKIA prime-site is shown here:

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