1. Source: GSM Association, 2010 Mobile Networks

2. Source: GSM Association, 2010 2 Coverage and Capacity Mobile communications networks are designed for both area coverage and capacity for expected voice and data calls.

3. Source: GSM Association, 2010 3 Network of Cell Sites Networks are made up of sites serving areas called cells. This may be shown as a honeycomb pattern but in practice cell shapes are not regular.

4. Source: GSM Association, 2010 4 Cell Area Depends on Geography and Calls Antennas must be near users. The size of each cell is dependent on the number of calls, the physical terrain and the frequency of operation.

5. Source: GSM Association, 2010 5 Cell Sites Served by Base Stations Each antenna site or base station consists of a mast or existing building to support the antennas and associated transmission and network equipment.

6. Source: GSM Association, 2010 6 The Mobile Switching Centre Connects Calls Base stations are connected to a mobile switching centre where a call is connected to another mobile or fixed phone or the Internet.

7. Source: GSM Association, 2010 7 Handover Between Cells while Moving As a mobile moves the call is passed between neighbouring cells, a process called handover. If there are gaps in the coverage the call could be dropped.

8. Source: GSM Association, 2010 8 Network Changed in Response to User Needs As the number of users grows the larger cells will be divided into smaller sizes. As the cell size decreases, so also does the transmit power.

9. Source: GSM Association, 2010 9 Mobile Networks & Mobile Phones The closer the mobile phone is to the antenna the lower is the power required by the phone to connect to it

10. Source: GSM Association, 2010 10 Need for Base Stations - Summary Low power transmitters. Limited geographic coverage. More sites for more users. Sites must be close to users. Need both network coverage and capacity for quality of service.