ation, the selected PLMN becomes the registered PLMN. The UE now continuously searches for the best cell on which to camp. The particular cell reselection process to achieve this depends on the cell reselection scenario, UE capabilities, subscriber priority class, and other factors (for details, see 3GPP R2-080238 [47]). Although the baseline for UE behavior in LTE has been that in GSM and WCDMA, a new (LTE-specific) aspect is the handling of priorities between available RATs and frequency layers. According to this priority scheme, a set of broadcasted system information parameters configures, for each UE, a default RAT and frequency layer priority list. In addition, the LTE RAN uses RRC signaling to configure a UE-specific priority list for each UE. The setting of the priority list provides network control to steer camping mobiles to particular RATs and frequency layers facilitating the camp load balancing that is one of the idle mode mobility drivers in 3GPP TS 36.300 [14]. More specifically, in the priority scheme, interfrequency and inter-RAT cell rese- lection relies on two sets of parameters. The first set is the cell-specific (and thereby frequency- and RAT-specific) set of parameters common to all UEs camping on specific RAT and frequency. The second set is the UE-specific set of parameters that provides the means to control UE behavior depending on UE class and, in gen- eral, operator-defined policy. Here, we focus on the cell parameters that need to be broadcasted in the cell (see Figure 4.20) and note that the UE-specific parameters are similar to the broadcasted ones listed in 3GPP TS 36.331 [21]. Figure 4.20 lists the parameters needed for interfrequency and inter-RAT cell reselection. The Thresh serving, low threshold is needed in order to compare the appro- priate S value of the serving cell when deciding if the UE can reselect to a lower- priority cell than the currently serving cell. On the other hand, the Thresh serving,high parameter is needed in order for the UE to know when it should trigger 