m acceptable level for the neighbouring cell. If a neighbour cell passes the S-criteria the cell re-selection is performed when a neighbour cell is ranked better than a serving cell. The ranking is based on the R-criteria. There are two parameters that affect the ranking: for a serving cell it is possible to define a hysteresis (Qhyst2) that applies on ranking to all neighbour cells and also individual offsets (Qoffset2) Radio Network Planning and Optimisation for each neighbour cell, which affects only one neighbour cell. Cell re-selection is performed when neighbour cell is ranked over a current serving cell (Rn > Rs). The cell re-selection procedure is different when GSM cells are involved in the ranking. The GSM measurements are activated when inter-RAT measurement criteria are met and the cell has GSM neigh- bours defined. There are no quality (Ec/No) measurements and the S-criteria only includes the level criteria (Qrxlevmin). Also, if even one GSM cells the ranking, the R-criteria is always evaluated using signal level measurements; for the WCDMA cells RSCP and for the GSM cells RX. The quality based hysteresis and individual offset values cannot be used; instead level based hysteresis (Qhyst1) and cell individual offset (Qoffset1) values are always used for signal level evaluations. Measurement Requirements The UE evaluates the S-criteria for the serving cell at least every DRX cycle. If the UE has not found any suitable cell in the neighbour list, it will start the PLMN selection procedure 12 seconds after the serving cell did not meet the S-criteria. If the measurement criteria (Sintrasearch, Sintersearch, SsearchRAT) are met the neighbour cells are measured based on TmeasureFDD and TmeasureGSM parameters. The measurement frequency is different for different types of neighbours: Intrafrequency neighbours: every TmeasureFDD Interfrequency neighbours: every Ncarrier-1)*TmeasureFDD GSM neighbours: every TmeasureGSM The UE evaluates the cell re-selection criteria for the cells, which have new measurement re