KPIs). This appendix seeks to give a short overview of Fundamentals of Cellular Network Planning & Optimisation A.R. Mishra. © 2004 John Wiley & Sons, Ltd. ISBN: 0-470-86267-X END-TO-END SYSTEM PERFORMANCE MEASUREMENT what these KPIs are, how they relate to user experience and how they are tested in practical networks. D.2 BASIC SYSTEM KPIs All the mobile networks have fundamental requirements of coverage and capacity. Coverage Coverage is normally expressed as location probability. This is usually given as a percentage. For example, a 95% outdoor location probability means that for 95% of the time, in 95% of the coverage area, the user will be able to make a call. Outdoor coverage can be measured by drive test equipment described in a later section. Such equipment uses some form of location equipment like global positioning system (GPS) and a test mobile phone attached to a laptop computer. Most of the testing is automated and the system is able to generate calls and then record a number of variables, coverage or signal strength in dBm being one of them. The link budget normally gives the threshold value, which the coverage test must meet. The sensitivity of mobile phones being specified at - 100 dBm for GSM 1800 band mobiles, this threshold is generally in the -95 dBm range. This represents the practical minimum signal strength below which the mobile cannot make a call. Indoor coverage is far more difficult to measure, since this calls for a 'backpack' mounted test equipment and is far more labour-intensive since the speed is limited to that of a person walking in the buildings. Also, gaining access to buildings is normally a time-consuming affair. For these reasons, indoor coverage is approximated by an outdoor drive test. This is done by deciding an additional margin for 'building penetration loss', which could be anywhere from 10 to 25 dB depending on how much indoor coverage is required (one wall penetration, two walls, basement coverage, etc). Using a typical figure of 20 dB building penetration loss, the 