ecovered. Successful RRC con- nection re-establishment requires that the target eNodeB has the UE context (basically all the information about the UE's current call parameters) of the incoming UE. Therefore, in LTE special arrangements are needed for the UE context delivery from the source eNodeB to the target eNodeB in order to achieve as high RRC connection re-establishment success rate as in wideband code division multiple access (WCDMA) networks. In WCDMA networks, the radio network controller (RNC) holds the UE context and therefore only in case of inter-RNC RRC connection re-establishment some type of context fetching by target RNC from source RNC is needed. In LTE, the UE context fetching can be enabled using MRO algorithms as shown in Chapter 14. Therefore, in order to minimize the dropped call rate in LTE networks the triggering of re-establishments should be minimized and on the other hand the success rate of the RRC connection re-establishment should be maximized. The UE handling of radio link problems is based on [4], [5] and [6] as shown below (it should be noted that additional triggers, on top of 3GPP-defined ones, for RRC connection re-establishments can exist in the UEs): Timer T310 expiry Maximum number of RLC retransmissions in uplink is reached Handover failure and timer T304 expiry Non-handover-related random access problem Timer T310 Expiry While in RRC-connected state the physical layer of the UE monitors the radio link quality based on the cell-specific reference signals of the primary cell (Pcell) as defined in [6]. The UE compares the downlink radio link quality estimation against the out-of-sync and in-sync thresholds (defined in [6]). The out-of-sync threshold, Qout, is defined as the level at which the downlink radio link cannot be reliably received corresponding to 10% block error rate (BLER) of a hypothetical PDCCH transmission taking into account the PCFICH errors. The in-synch LTE Key Performance Indicator Optimization The UE detects up to N310 -> UE The UE detects starts timer T3