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Inter-RAT Cell Reselection Trial. Objective. To find a good balance between coverage and performance for LTE by adjusting UMTS reselection to LTE. Background Information. Idle mode reselection parameters from LTE to UMTS and vice versa was set to -110 dBm for the market
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Objective • To find a good balance between coverage and performance for LTE by adjusting UMTS reselection to LTE
Background Information • Idle mode reselection parameters from LTE to UMTS and vice versa was set to -110 dBm for the market • 30% RRC MO-Signaling: UE ping pong from LTE to UMTS with high RRC failures • Reselection from UMTS to LTE was set to AT&T GSV of -104 dBm while LTE to UMTS was retained at -110 dBm • 12% RRC MO-Signaling, reduced RRC failures due to signaling • 20% ERAB attempts lost • 6 dB reselection hysteresis may be too high
Summary of UMTS SIB19 Impact • Negligible impact seen on Accessibility and Retainability • Increased RRC, ERAB and S1 Signaling Attempts • RRC Distribution shows a 6% (abs) increase in RRC MO signaling • Threshhigh at 16 – RRC signaling at 12% • Threshhigh at 14 – RRC signaling at 18% • Traffic increase • Small Increase in IRAT Session Continuity to WCDMA • Throughput is unchanged
Parameterization • UMTS • Threshhigh – 16 (Gold Standard Value, initial value) • Threshhigh – 14 (Current Setting) • LTE (idle mode) • EUtranCellFDD: qRxLevMin: -120 (GSV) • EUtranCellFDD: sNonIntraSearch:10 (GSV) • EUtranCellFDD: threshServingLow:10 (GSV) • LTE (dedicated mode) • ReportConfigEUtraBadCovPrim: a2ThresholdRsrpPrim: -115 (Current Setting) Idle Mode Behaviour UE reselects to UMTS when RSRP falls below -110 dBm and UE reselects to LTE when LTE measured RSRP is -106 dBm Dedicated Mode Behaviour UE will IRAT to UMTS when RSRP is -116 dBm (-115 dBm + 1 dB hysteresis). UE will remain in LTE longer when in dedicated mode.
