Science & Technology in Action

Mobile devices are changing our world 
In the past, certain technologies have brought about significant and unforeseen changes in society. Well known examples of such technologies are the printing press, railways and electricity. However, no previous technology has had the dramatic impact of the mobile device. For example, there were no mobile phone subscribers in 1982. Today, some thirty years later, nearly 85% of the world’s population have mobile phones. This extraordinary situation illustrates our fascination with the mobile devices that have begun to dominate our lives. However, none of these devices could communicate without the telecommunications network that connects them together. 

In this lesson we look at some of the fundamental science associated with mobile devices and the network that allows them to connect with the internet and with each other, and then discuss some of the many ways these technologies are influencing our lives. 

The mobile network provides the connectivity 
There are many types of mobile device, including, smartphones, laptops and tablets. Mobile devices use radio waves called microwaves, to send and receive information. This information may be a voice call, a text message, an email, images, video or a web page. To illustrate how a mobile network operates we will use the example of a phone call. When you switch your phone on, it finds and connects to a transceiver called a base station. If you dial a friend’s number, the base station locates your friend’s phone and the connection is set up. 

A mobile network is comprised of a number of these base stations. They are usually located on tall steel towers, often disguised as trees. However, in cities, where each cell covers a relatively small geographical area, they might be located on the roofs or walls of buildings. 

Each base station serves a limited geographical area called a cell. This is why mobile phones are also called cell phones. Each cell can deal only with a certain number of simultaneous connections. However, there are lots of them and the areas are often small, especially in large cities. When a user moves between cells, one cell is said to handover the connection to the next cell without interruption. This freedom of movement is one of great strength of mobile technology. 

All of the base stations are connected, often by high speed optical fibre cable, to a control centre called a Mobile Telephone Switching Office (MTSO). All enabled mobile devices have certain codes associated with them and the MTSO checks these codes in order to authorise a connection. The MTSO also routes calls between base stations and, when required, to the fixed telephone network or the internet. 

This flexibility means that a user can readily make connection with another user or with a website. Connectivity is the other great attribute of mobile networks.