asic assignment Basic assignment Basic assignment Ciphering Ciphering Ciphering Ciphering External HO, SDCCH or TCH source Internal HO inter, SDCCH or TCH source Internal HO inter, SDCCH or TCH source Internal HO inter, SDCCH or TCH source MM signalling MM signalling MM signalling MM signalling MM signalling MM signalling Release 25170 Release Release Release Release Release Release SMS establishing SDCCH SMS establishing SDCCH SMS establishing SDCCH SMS establishing SDCCH paging/initial MS 12134 Figure 2.48 SDCCH observation example ome alarms appear when another alarm has exceeded a certain threshold. Some other alarms have no ignification if not associated with other alarms. Therefore why analysis requires a certain concentration 0 understand the origin of the problem properly. An optimisation engineer uses, as described before, statistics and drive tests to identify and analyse a problem. However, he/she can resort to using alarms, but only as a confirmation of a suspected hardware Radio Network Optimisation anomaly. In fact, analysis is first done on radio settings (parameters, interference, site engineering, etc.). If nothing seems suspicious, then alarms can help to state hardware problems. Thousands of alarms exist but only a few of them directly explain QoS problems. The most relevant ones to the Optimisation Team are those concerning a BTS hardware fault, a transmission link high error rate or intrinsic database incoherence. This latter one is especially related to adjacent cell configuration errors and is dealt with in the handover performance section later in the section. The clearance of the origin of the alarm leads to its cancellation by replacement of the faulty hardware, where readjustment of the transmission link or correction of the database are the main actions that will be done in order to improve QoS from an alarm perspective. Transmission Network Auditing Although this subject is dealt with in Chapter 3, a brief reference is necessary at this point as transmission problems can affect KPIs i