l is used as the reference point for addition and the drop window. Event 1D is informative and allows the RNC to send new information, e.g. to update measurement control or the service area code. Parameters to Optimise SHO Addition/drop window size has a large impact on SHO areas. The addition window sets when the SHO is triggered; a small value for the addition window would trigger an SHO already close to the best cell in the active set. A drop window sets when the SHO branch is removed; a large value would keep the SHO connections far from the best cell in the active set. The relative difference between the addition and drop windows would set the size of the SHO area. The cell individual offset (AdjsEcNoOffsett) can be used to extend or limit the SHO area for an individual neighbour. With a positive offset the SHO is taking place earlier and with a negative offset the SHO is delayed. In the case where the cell is an unreliable reference point for SHO triggering with a disable effect on the reporting range (AdjsDERR) parameter, the cell can be set SO that it does not have an impact on the reporting range. Inter-RNC Soft Handover In the case where a mobile crosses an RNC border the mobile needs to perform an inter-RNC handover. If an Iur link is defined between the RNCs, a soft handover is possible, but in the case of a missing Iur link the mobile makes an intrafrequency hard handover. Radio Network Planning and Optimisation In the case of an inter-RNC SHO the mobile is controlled by a serving RNC (SRNC). The RNC that allocates resources but does not make decisions is called a drift RNC (DRNC). When the mobile crosses an RNC border the drift RNC becomes the serving RNC by a process called SRNC re-location. If SRNC re-location is not supported the original SRNC controls the DRNC resources, even after the UE has crossed the RNC border and no SRNC cells are in the UE active set. This process of not re-allocating RNC resources is called anchoring. Intrafrequency Hard Handover An intrafrequency hard handover is also p