How are mobile phone networks planned and built?
Today, almost everyone in Germany owns a mobile phone. More people use their phones and smartphones for data transmission and internet access as well as for making calls or sending texts. An extensive infrastructure is needed to ensure that people are able to communicate using their mobile phones, wherever where they are, especially in an emergency. How are mobile phone networks planned and built? What technical requirements need to be met?
In 25 % of the almost 40 million households in Germany, the mobile phone has already replaced the land line. With about 110 million mobile phone contracts nationwide, the number of SIM cards issued far exceeds the total population. As well as traditional telephony, mobile internet access plays an increasingly important role. To meet the ever-increasing demand for a high quality network, mobile phone providers invest extensively in extending their networks. This means complex logistical planning and careful coordination with local authorities.
Installation of a mobile phone base station
Mobile phone networks consist of radio cells that are arranged in a honeycomb structure. Base stations, the nodes of the networks, provide the radio cells with a signal. When planning mobile phone sites, the operator needs to determine how the individual radio cells should be shaped in order to ensure an optimum coverage for users; phone calls, internet surfing with mobiles phones, smartphones, tablets or tablet PCs are all considered. Finally, the decision must be made, where to build new base stations. Apart from planning new networks, mobile operators also need to improve the existing infrastructure. This also requires complex planning. The operator’s goal is to provide optimal service for an increasing number of users operating many types of devices.
Requirements for planning mobile networks
These general requirements lead to specific demands in planning and construction: network coverage is vital; high quality speech and data transmission must be guaranteed; the capacity for new users must be factored in, as well as good coverage inside buildings.
When planning a radio network, it must be ensured that the structure of the adjacent cells is as regular as possible and that cells are an exact match. This is important because a change to the properties of one radio cell will automatically influence the radio waves of the adjacent cells. Big and small cells are mixed within a network to cover areas with high demand, such as city centres, airports or train stations.
Important parameters for planning mobile networks
The key factor when planning mobile phone networks is calculating the propagation of electromagnetic waves, on which radio transmissions are based. In contrast to radio and television transmitters, the mobile phone network antennas of GSM and UMTS networks are short because of the small geographic reach of the cells. Planning a mobile phone transmitter site therefore requires much more precise calculation than is the case for broadcasting stations.
Other parameters must also be considered when planning a mobile phone network. Radio signals can be weakened or diverted by natural obstacles, buildings or even the weather. The network’s traffic levels over a day, week or year need to be estimated, as these can be quite varied. Computer models have been developed to carry out such calculations for mobile networks. They can simulate and display radio wave propagation depending on the landform or on buildings.
When planning an individual base station, network planners first establish the search radius, which considers the geography of the area. At this early stage, the operator will already have informed the local authorities of their project. The network operator will then check the types of buildings within the search radius. High towers, chimneys or buildings are suitable for setting up mobile phone base stations. It may be that special radio wave measurements at the site are needed to find out whether the site meets the requirements for sending and receiving signals.
Once the planners, in cooperation with the local authorities, have decided on a suitable site for the base station, construction starts. First, the operator negotiates a lease with the owner of the building that will house the base station. Then architects develop a construction plan which shows the location of antennas and electronics units. Their plans must comply with the relevant requirements of the building regulations, preservation orders and nature conservation law.
The network operator then applies for a site certificate from the independent Federal Network Agency for Electricity, Gas, Telecommunications, Post and Railway (Bundesnetzagentur), which is a legal requirement for operation. From the construction plans and technical specifications, the Federal Network Agency will determine safe distances for the installation. This data and the details of the antenna construction will be part of the site certificate.
Once the document has been issued, the network operator submits it to the local authority and relevant environmental authority. It takes at least two weeks before the base station can start operating: the technology has to be installed and tests run to allow detailed measurements. The base station is only allowed to go live once all the tests have been successfully completed. All base stations and latest measurements are publicly available in the site database of the Federal Network Agency (http://emf2.bundesnetzagentur.de/en_emf_mon.html).
Local authorities can also register with the database to access additional information about existing systems and their corresponding safe distances.