Accessibility KPI
- Sudden Drop in RRC Setup Success Rate after Software Upgrade
Scenario: Post-upgrade, RRC SSR drops by 15% in a dense urban cluster. Users report registration failures. Traffic load is stable.
Answer:
- Counters: Setup.Attemptvs. RRC.Setup.Success (Ericsson: LTE_ERAB_ESTAB_ATT/SUCC).
- Parameters: PRACH preamble power (preambleInitialReceivedTargetPowerfor Nokia), SIB1 scheduling periodicity.
- Fix: Adjust PRACH power, increase maxRrcRetransmissions, validate SIB1 alignment.
- High RACH Failures in Stadium during Peak Events
Scenario: During concerts, UEs fail random access; RACH.Preamble.Timeout spikes.
Answer:
- Counters: Attemptvs. PRACH.Success (Ericsson: RACH_ATTEMPTS_TOTAL).
- Parameters: PRACH configuration index (Nokia: prachConfigIndex), contention-based preamble ratio.
- Fix: Increase PRACH occasions, enable dynamic preamble splitting.
- Inconsistent VoNR Call Setup Success Rates
Scenario: VoNR calls fail intermittently; INITIAL_CONTEXT_SETUP_FAIL logs appear.
Answer:
- Counters: Setup.Success(Ericsson: NR_VOICE_CALL_ESTAB_SUCC).
- Parameters: QoS mapping for SIP signaling (Nokia: qciProfileTable), AMF overload thresholds.
- Fix: Prioritize QCI 1 bearers, adjust AMF nfLoadThreshold.
- Paging Channel Congestion in High-Density Area
Scenario: UEs miss paging during busy hours; Paging.Discard.Rate exceeds 10%.
Answer:
- Counters: Overload(Ericsson: PAGING_OVERLOAD_IND).
- Parameters: Paging cycle (defaultPagingCycle), paging group size.
- Fix: Shorten paging cycle to 64 ms, split paging groups.
Retainability KPI
- Spike in RLF during Highway Mobility
Scenario: 30% RLF increase on a highway; interference spikes during handovers.
Answer:
- Counters: Detected(Ericsson: COUNTER_RLF_DETECTED_TOTAL).
- Parameters: T310 timer, A5 thresholds (interFreqHoA5Thresh2for Nokia).
- Fix: Extend T310 to 2s, adjust A5 thresholds for earlier HO.
- High Abnormal Releases in Dense Urban Mall
Scenario: ERAB.AbnormalRel.Cause shows “Radio Connection Lost” in crowded areas.
Answer:
- Counters: Release.Abnormal(Ericsson: E-RAB_ABNORMAL_REL_CAUSE).
- Parameters: UL power control (p0NominalPUSCH), DRX inactivity timer.
- Fix: Optimize UL power control, reduce DRX inactivity timer.
- Frequent Drops Due to UL Sync Loss
Scenario: UEs lose UL sync; UL.TimeAlignment.Timer.Expiry spikes.
Answer:
- Counters: Failure(Ericsson: UL_SYNCHRONIZATION_LOSS).
- Parameters: Time alignment timer (timeAlignmentTimer), UL SPS configuration.
- Fix: Increase timeAlignmentTimer, enable UL SPS for stationary UEs.
- Cell Reselection Failures in Suburban Area
Scenario: UEs drop during reselection from 5G to 4G; SIB3 parameters misaligned.
Answer:
- Counters: Resel.Fail(Ericsson: CELL_RESEL_FAILURE).
- **Parameters: qRxLevMinfor LTE,threshX-High` for NR.
- Fix: Adjust LTE qRxLevMinto -122 dBm, prioritize NR anchor.
Handover KPI
- Intra-Frequency Ping-Pong in Urban Grid
Scenario: UEs oscillate between cells; HO.PingPong.Rate exceeds 20%.
Answer:
- Counters: Prep.Failure(Nokia: LTE_HO_PREP_FAILURE).
- Parameters: A3 offset (a3Offset), TTT (timeToTrigger).
- Fix: Increase A3 offset to 4 dB, set TTT to 480 ms.
- Inter-RAT Handover Failures (5G to 4G)
Scenario: NR-to-LTE.HO.Failure due to S1 interface delays.
Answer:
- Counters: Failure(Ericsson: INTER_RAT_HO_FAIL).
- **Parameters: hoPrepTimer(Ericsson), s1HoMaxRetries` (Nokia).
- Fix: Extend hoPrepTimerto 3s, enable S1 fast retry.
- VoLTE Handover Drops in Suburban Clusters
Scenario: VoLTE calls drop during HO; SRVCC.Failure counter increments.
Answer:
- Counters: Attemptvs. SRVCC.Success (Ericsson).
- **Parameters: srvccHoThreshold(Nokia), volteHoMargin` (Ericsson).
- Fix: Lower srvccHoThresholdto -110 dBm, pre-configure SCC APNs.
- X2 Handover Failures Due to Resource Allocation
Scenario: Target cells reject HO due to PRB congestion; X2.HO.Reject spikes.
Answer:
- Counters: HO.Reject.Cause(Ericsson: X2AP_HO_FAIL).
- **Parameters: dlPrbUsageThreshold(Nokia), hoPrbMargin` (Ericsson).
- Fix: Activate load-aware HO, reserve PRBs for HO UEs.
Throughput KPI
- UL Throughput Degradation in TDD Band
Scenario: UL throughput drops to 20 Mbps despite 64QAM; UL.IBLER exceeds 25%.
Answer:
- Counters: IBLER(Ericsson: UL_IBLER_AVG).
- **Parameters: UL/DL slot ratio (tddUlDlConfig), ulTargetIbler`.
- Fix: Reconfigure TDD pattern to 7:3, set ulTargetIblerto 10%.
- Poor Cell-Edge Throughput with Strong RSRP
Scenario: Edge users report <10 Mbps; CQI.0to6.Ratio is 40%.
Answer:
- Counters: Distribution(Nokia: LCELL_CQI_DISTRIB).
- **Parameters: PDSCH EPRE (pdschEpreOffset`), cell-specific reference signals.
- Fix: Boost PDSCH power by 3 dB, enable FFR (Fractional Frequency Reuse).
- MU-MIMO Throughput Inconsistencies
Scenario: MU-MIMO users see erratic throughput; RankIndicator.1 dominates.
Answer:
- Counters: Rank.2(Ericsson: MIMO_RANK2_UTIL).
- **Parameters: muMimoPairingThreshold(Nokia), csiRsPower` (Ericsson).
- Fix: Adjust pairing threshold to -8 dB, optimize CSI-RS power.
- CA Throughput Drop after SCell Addition
Scenario: Throughput drops post-SCell activation; SCell.BLER spikes.
Answer:
- Counters: DL.BLER(Ericsson: SCELL_BLER_AVG).
- **Parameters: sCellAddModThreshold(Nokia), caPowerOffset` (Ericsson).
- Fix: Increase sCellAddModThresholdto -8 dB, balance power offsets.
Latency KPI
- DL Latency Spikes in IoT Applications
Scenario: NB-IoT devices experience 200 ms latency; DL.Scheduler.Delay peaks.
Answer:
- Counters: Scheduler.Delay(Ericsson: DL_SCHEDULER_DELAY).
- **Parameters: npuschMinPeriodicity(Nokia), iotSchedPriority` (Ericsson).
- Fix: Prioritize IoT traffic via QCI 9, reduce NPUSCH periodicity.
- High Latency during Handovers
Scenario: Latency exceeds 100 ms during HO; HO.Interruption.Time is 80 ms.
Answer:
- Counters: Interruption.Time(Nokia: LTE_HO_INT_TIME).
- **Parameters: hoExecutionTimer(Ericsson), makeBeforeBreak` (Nokia).
- Fix: Enable “make-before-break” HO, reduce hoExecutionTimerto 50 ms.
- Inconsistent URLLC Latency in Factory Automation
Scenario: URLLC packets miss 1 ms target; PDCP.UL.Delay varies widely.
Answer:
- Counters: Latency(Ericsson: PDCP_UL_LATENCY_AVG).
- **Parameters: preemptionCapability(Nokia), urllcSlicingFactor` (Ericsson).
- Fix: Enable pre-emption, dedicate URLLC slicing with 20% PRB reservation.
- High TCP Retransmission Latency in Video Streaming
Scenario: Video buffering due to TCP retransmissions; RLC.Retrans.Rate is 15%.
Answer:
- Counters: ARQ.Retrans(Nokia: RLC_DL_ARQ_RETRANS).
- **Parameters: rlcAmMaxRetrans(Ericsson),tcpSlowStartThreshold`.
- Fix: Reduce rlcAmMaxRetransto 2, tune TCP slow-start parameters.
