How Mobile Phone Network Coverage Works

A mobile phone network is a simply a system of radio towers (or base stations) set up across the country, which allows information to be sent and received from mobile phones.

Your mobile phone needs a certain minimum radio signal strength to ensure adequate reception; your signal strength will decrease rapidly as you move away from a base station. This means that an extensive network of base stations is needed to ensure adequate coverage throughout the UK. There are currently about 45,000 radio base station sites in the UK - 30,000 of these are located on existing buildings, rooftops, or lamp posts.

Each base station provides a certain amount of coverage, depending on the following criteria:

• the physical terrain (signals are blocked by trees, buildings or hills),
• the frequency band that the network operates on (the higher the frequency, the smaller the area covered),
• the number of calls the station will have to deal with.

Consequently, base stations are spaced about 200 to 500 m apart in towns and 1 to 3 miles apart in the countryside. The spacing of the stations can be represented by a honeycomb structure, with each station in the middle of each hexagonal (or cell). These cells overlap at the edges to make sure that you can receive a signal when moving from one area to another.

Mobile network operators often try to share base station sites, such as masts or towers. However, this is not always possible, as the radio frequencies that the different operators use are not always compatible and could interfere with existing antennas.

More base stations are currently being added to UK networks as part of a programme to improve the infrastructure for the existing mobile generation (2G) and create a new network for 3G.

These new base stations are needed as each cell can only support a limited number of mobile phone calls at any one time. If customer demand is too high for one cell, then another mast is added between the existing cells to create additional smaller cells.

The new 3G networks need to transmit large amounts of information and operate at a higher frequency. In order to do this, they must use smaller cells, and overlap more than the current 2G cells.