 in Figures 12.23 and 12.24. 12.5.1 Handover Performance The intra-LTE, intra-frequency handover execution success rate is defined from source eNodeB point of view as number of received RRC connection reconfiguration complete messages by E-RAB drop rate E-RAB setup attempts 22,000 20,000 18,000 16,000 14,000 12,000 10,000 Day 1 Day 2 Day 3 Figure 12.22 Average E-RAB drop rate and total amount of E-RAB setup attempts in a cluster during moderate traffic (15 minutes statistics collection period) LTE Key Performance Indicator Optimization Handover execution success rate E-RAB drop rate Day 1 Day 2 Day 3 Figure 12.23 Average intra-frequency handover execution success rate and average E-RAB drop rate in a cluster during moderate traffic (15 minutes statistics collection period) Handover execution success rate (%) Figure 12.24 E-RAB drop rate as a function of intra-frequency handover success rate averaged over cluster of cells during moderate traffic (15 minutes statistics collection period) LTE Small Cell Optimization Source Target PDCCH/DCI2/C-RNTI ; PDSCH/DL-SCH/DCCH/SRB1: RRC Connection Reconfiguration (Measurement Configuration) PDCCH/DCI0/C-RNTI ; PUSCH/UL- SCH/DCCH/SRB1: Measurement Report Handover Decision X2AP: Handover Request Resource Allocation X2AP: Handover Request Acknowledge X2AP: SN Status Transfer PDCCH/DCI2/C-RNTI ; PDSCH/DL-SCH/DCCH/SRB RRC Connection Reconfiguration (with mobility control information) MSG1 - RACH: RA Preamble MSG2 - PDCCH/DCI1A/RA-RNTL/ / PDSCH MSG3 - PUSCH/UL-SCH/DCCH/SRB1: RRC Connection Reconfiguration Complete S SAAP Path Switch Request PDCCH/DCI2/C-RNTI ; PDSCH/DL-SCH/DCCH/SRB1 Connection Reconfiguration (Measurement Configuration) S1AP: Path Switch Request Acknowledge PDCCH/DCI0/C-RNTI ; PUSCH/UL-SCH/DCCH/SRB1 Connection Reconfiguration Complete X2AP: UE Context Release Figure 12.25 Inter-eNodeB handover signalling using contention-free random access procedure target cell that leads to release request message received over X2 or received UE context release command message rec