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Mpcs la lte ho parameters trial. Overview. A study on the effect of handover parameters on the network performance will be done in a trial cluster (part of Cerritos)
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Overview • A study on the effect of handover parameters on the network performance will be done in a trial cluster (part of Cerritos) • The parameter change to be implemented as an iterative process with each drive and the results to be compared to analyze the effect of the parameters • Following parameters to be changed A3offset; hysteresisA3; filtercoefficientEutranRsrp; sMeasure; timetotriggerA3
Review: LTE HO • Evaluates if one or more intra frequency cell is better than current serving cell • UE receives measurement configuration in RRC Connection Reconfiguration • No measurement list sent to UE (UE search for all 504 physical cell id and reports the cell(s) fulfilling the event criteria). • UE Event Trigger controlled by: – Filtering (How much averaging is done before event evaluation) – Offset (How much better in dB) – Time to trigger (For how long)
Main Trigger Parameters • sMeasure = 0 { -140..-44, 0 } [dBm] Controlling if the UE is required to perform measurements. Disabled if set to “0” (used only RSRP is the trigger) • a3offset = 30 { -150..150 } [0.1 dB] Offset value for EventA3, added to serving cell • hysteresisA3 = 10 { 0..150 } [0.1 dB] Hysteresis value for eventA3, added to neighbor cell • timeToTriggerA3 = 40 { 0, 40, 64, 80, 100, 128, 160, 256, 320, 480, 512, 640, 1024, 1280, 2560, 5120 } [ms] Time after Event A3 is fulfilled when UE starts to send Measurement reports • triggerQuantityA3 = RSRP [RSRP,RSRQ] The quantity that triggers the event • cellIndividualOffsetEUtran Offset value specific to a neighbor relation
Handover Filtering • To avoid that the measurement reporting is triggered by fast fading, the measurement configuration contains filter coefficient for the UE to use • filterCoefficientEUtraRsrp = 9{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 15, 17, 19 } Filter coefficient for RSRP measurements • filterCoefficientEUtraRsrq = 11{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 15, 17, 19 } Filter coefficient for RSRQ measurements
Event A3: A neighbour cell(b) becomes offset better than serving cell(a)
Baseline Test Cases (contd) • Baseline2 drive demonstrated the highest number of handovers and the smallest delta in RSRP/RSRQ.
Baseline Test Cases (contd) • Baseline drive demonstrated the best SINR performance.
A3offset Test Cases (contd) • There was a clear decrease in the number of handovers and an increase in the RSRP/RSRQ delta as went from a3offset=0 to a3offset=40. • This is expected as the sum of hysteresisA3 and a3offset increases. Notice, as expected, Delta RSRP ~ hysteresisA3+a3offset.
A3offset Test Cases (contd) • Baseline (smallest offset) demonstrated the best SINR performance.
HysteresisA3 Test Cases (contd) • There was a clear decrease in the number of handovers and an increase in the RSRP/RSRQ delta as went from hysteresisA3=20 to hysteresisA3=80. • This is expected as the sum of hysteresisA3 and a3offset increases. Notice, as expected, Delta RSRP ~ hysteresisA3+a3offset.
HysteresisA3 Test Cases (contd) • hysteresisA3=20 (smallest hysteresis) demonstrated the best SINR performance.
TimeToTriggerA3 Test Cases (contd) • Number of handovers decreased and RSRP/RSRQ delta increased with the increasing timeToTrigger. This is as expected.
TimeToTriggerA3 Test Cases (contd) • timeToTriggerA3=0 and Baseline(40) demonstrated the best SINR performance.
FilterCoefficientEutraRSRP Test Cases (contd) • Number of handovers decreased and RSRP/RSRQ delta increased with the increasing filterCoefficientEUtraRsrp. • This is as expected as the number of measurement samples analyzed for each handover increases.
FilterCoefficientEutraRSRP Test Cases (contd) • Baseline gave the best SINR performance.
sMeasure test cases (contd) • No apparent trend was observed between these drives.
sMeasure test cases (contd) • The effect of sMeasure parameter on the network is inconclusive in regards to the performed drives.
Summary • Tested parameters for the most part resulted in the expected behavior: • Number of Handover events. • RSRP/RSRQ delta upon Handover. • Pre-handover SINR performance. • Part of the unexpected behavior can be attributed to the variation in drive test setup between some of the drives. • The effect of sMeasure parameter on the network is inconclusive at this point. It will be further analyzed during the testing on DAS nodes. • Current Baseline is pretty suitable to the network at this early stage of operation. It is recommended that optimization, when performed, be performed on a case by case basis.