 goes around in the various parts of the network. Based on the DCR, CSR, HO, etc., parameters, the quality of the network can then be analysed. Apart from drive testing, the measurements can also be generated by the network management system. And finally, when 'faulty' parameters have been identified and correct values are determined, the radio planner puts them in his network planning tool to analyse the change before these parameters are actually changed/implemented in the field. RADIO NETWORK PLANNING AND OPTIMISATION Drive Testing The quality of the network is ultimately determined by the satisfaction of the users of the network, the subscribers. Drive tests give the 'feel' of the designed network as it is experi- enced in the field. The testing process starts with selection of the 'live' region of the network where the tests need to be performed, and the drive testing path. Before starting the tests the engineer should have the appropriate kits that include mobile equipment (usually three mobiles), drive testing software (on a laptop), and a GPS (global positioning system) unit. When the drive testing starts, two mobiles are used to generate calls with a gap of few seconds (usually 15-20 s). The third mobile is usually used for testing the coverage. It makes one continuous call, and if this call drops it will attempt another call. The purpose of this testing to collect enough samples at a reasonable speed and in a reasonable time. If there are lots of dropped calls, the problem is analysed to find a solution for it and to propose changes. An example of a drive test plan is shown in Figure 2.16. Some typical drive tests results giving the received power levels from own cell and neighbour cells, FER, BER, MS power control, etc., are shown in Figure 2.17. Legend MS2 RxLew Sub (dBr Color RxLev Sub (d -120.00 100.00 -100.00.-90.00 -90.00.-80.00 -80.00-70.00 70.00.10.00 Size RxQual Sub 0.00.2.00 2.00-4.00 4.00-6.00 6.00.7.00 Symbol Mode (Num 1.00 - 1. 1.50 - 2.50 2.50.3.50 3.50-4.50 4.50-6.50 5.50.6.00 MS2 Dropped