Base stations use radio signals to connect mobile devices to the network, enabling people to send and receive calls, texts, emails, pictures, web, TV and downloads. Without base stations, mobiles will not work. They are made up of three main elements:
An antenna (or several antennas) to send and receive radio signals. These are typically between 0.5 and 2.5 metres long
A supporting structure such as a mast or building to hold the antenna(s) in the air
Equipment to power the base station and radio equipment, which is housed in protective cabinets.
Base stations are connected to each other and telephone exchanges by cables or wireless technology such as microwave dishes, to create a network. The area each base station covers is called a cell. Each cell is usually split into three sectors, which overlap with the sectors of neighbouring cells so the network is uninterrupted. When people travel between cells, the signal is handled by the new base station without a break in service.
The size and shape of each cell is determined by the features of the surrounding area, such as buildings, trees and hills, which can block signals. Cells are largest in flat open landscapes, where they can cover a radius of several kilometres. Cells in urban areas typically cover up to a two kilometre radius. The smallest cells, covering a few tens or hundreds of metres, are in built up areas, where micro-cell base stations are used to provide extra coverage and capacity. Femtocells can provide coverage within a room or a small building.
Each base station can only handle a limited number of connections at a time. In areas of high demand, additional antennas are sometimes added to a base station to send and receive more calls and other mobile services, or an extra base station is installed.
All this means a large number of base stations are needed to allow more people to use more mobile services, from more locations, and for coverage to be continuous when they move around. Most people welcome improved coverage and services. But we recognise that expanding our network can cause concern, usually about the visual impact of base stations or health issues concerning radio frequency (RF) fields.