he relevant measurements, measurements are classified as gap-assisted or non-gap-assisted. A non-gap-assisted 6.13 3GPP LTE radio resource control functions measurement is a measurement on a cell that does not require transmission/reception gaps to allow the measurement to be performed. A gap-assisted measurement is a measurement on a cell that does require transmission/reception gaps to allow the measurement to be performed. Gap patterns are configured and activated by the RRC functional block [13]. The handover procedure is performed without EPC involvement; i.e., preparation messages are directly exchanged between the eNBs. The release of the resources at the serving eNB (or source eNB) during the handover completion phase is triggered by the eNB. Figure 6-29 illustrates the handover procedure between eNBs within the same MME/S-GW. More information on the handover procedure can be found in reference [13]. After the downlink path is switched at the S-GW, downlink packets on the forwarding path and on the new direct path may arrive interchanged at the target eNB (see Figure 6-29). The target eNB should first deliver all forwarded packets to the UE before delivering any of the packets received on the new direct path. On handover, the serving eNB sequentially forwards all downlink PDCP SDUs that have not been acknowledged by the UE to the target eNB. The serving eNB discards any remaining downlink RLC PDUs. Correspondingly, the source eNB does not forward the downlink RLC context to the target Measurements to be performed by a UE for intra-/inter-frequency mobility can be controlled by E-UTRAN, using broadcast or dedicated control/signaling. In the RRC_IDLE state, a UE follows the measurement parameters defined for cell reselection. In the RRC_CONNECTED state, a UE follows the measurement configurations specified by RRC managed by the E-UTRAN. Intra-frequency and inter-frequency neighbor cell measurements are defined as follows: Neighbor cell measurements performed by the UE are intra-frequency measurements when c