uld be monitored such as traffic, timing advance, TRX quality, SDCCH drop, handover distribution, handover failures, etc. Statistics present the advantage of providing deep analysis to the cell level. On the other side, they present the disadvantage of not giving any geographical approach. This last issue is well mastered through drive testing. Drive Testing Performing a drive test is always the best way to localise geographically and analyse a problem. While statistics give an idea about the real behaviour faced by all end users regardless of their geographical location, drive testing or walk testing bring a simulation of end user perception of the network on the field from one call perspective. The only drawback of this method is complexity. In fact, drive testing can model the behaviour of up to five mobiles, but in order to analyse objectively a scenario, many attempts should be performed in the same conditions. For logistics reasons, this cannot be performed on the entire network, which is why drive tests and statistics are complementary methods. Both of them are necessary for optimisation engineers to assess the network performance. Outdoor drive tests are also used to assess indoor coverage. Therefore, in a dense urban area, by assuming a certain building penetration loss (in general 20 dB is considered), the indoor signal is estimated to be 20 dB less than the outdoor level. If -80 dBm is then accepted as a good indoor level, the outdoor level should be at least -60 dBm. Radio Network Planning and Optimisation Figure 2.46 Drive testing system mounting In the market, many tools exist where the idea is almost the same (see Figure 2.46). One or more handsets, configurable on different technologies like GSM 900/1800/1900, IS95, IS136 and AMPS, mounted on a car kit and connected via a cable to a laptop, report measurements for specific software. This application permits online visualisation on a map or a graph of different parameters (level, quality, serving cell identity, etc.). A globol positioning system (G