📡 Optimizing 5G Handover
In 5G, handover (HO) is the most critical mobility function ensuring seamless user experience, consistent
throughput, and service continuity. Poorly tuned HO parameters lead to call drops, ping-pong handovers,
and reduced user QoE.
🔍 Why Handover Optimization Matters
• Capacity: Balances traffic across cells efficiently.
• Coverage: Ensures users stay connected without blind spots.
• Throughput: Maintains data sessions without interruption during mobility.
• Reliability: Reduces dropped calls and unnecessary signaling.
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📊 Key Nokia KPIs & Counters for HO Optimization
1️⃣ Handover Success Rate (HOSR)
• KPI: IRATHOExecSuccRate
• Counters: pmHoExeAtt, pmHoExeSucc
• Issue Solved: Low success → call drops & mobility failures.
• Improvement: Tune HO preparation/trigger timers; optimize CIO bias.
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2️⃣ Ping-Pong Rate
• KPI: HOPingPongRate
• Counters: pmHoExeAtt, pmHoExeRet
• Issue Solved: Excessive unnecessary HOs → signaling load & degraded QoE.
• Improvement: Adjust Time-to-Trigger (TTT) & hysteresis; refine neighbor cell list.
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3️⃣ Handover Interruption Time
• KPI: HOInterruptionTime
• Counters: pmHoExeSucc, pmHoExeReestabSucc
• Issue Solved: Longer interruptions → poor VoNR/VoIP call experience.
• Improvement: Ensure Xn/S1 HO configurations are optimized; enable fast HO execution.
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4️⃣ HO Failure Rate due to Radio Conditions
• KPI: HOF due to Radio Link Failure (RLF)
• Counters: pmHoExeFailRadio, pmRadioLinkFail
• Issue Solved: Coverage gaps, weak neighbor relations.
• Improvement: Optimize PCI planning; adjust HO thresholds; enhance neighbor cell definitions.
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🛠 Case Example
A cluster shows high ping-pong rate (15%) and low HOSR (85%).
• Analysis: Too aggressive CIO bias causing premature HOs.
• Action: Increased TTT, fine-tuned CIO, cleaned neighbor relations.
• Result: HOSR improved to 95%, Ping-Pong reduced to 5%, leading to better user throughput & session
stability.
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⚙️ Optimization Insights
Handover tuning is not a one-time fix — it’s a continuous cycle of monitoring KPIs, analyzing counters,
and aligning mobility strategy with user QoE and capacity goals.
By layering Nokia HO counters with field measurements, engineers can pinpoint failures, minimize
signaling waste, and deliver truly seamless mobility in 5G networks.
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💡 What’s your biggest challenge in 5G Handover Optimization — is it ping-pongs, failures, or coverage
gaps?
📌 Optimizing 5G Retainability
Stable connectivity is the backbone of any high-performing 5G network. Retainability reflects how
reliably user sessions are sustained after successful establishment. Drops due to handover failures, RLFs,
or bearer issues can seriously degrade user experience—even in high-throughput scenarios.
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📍 Key Focus Areas:
1. RRC Retainability
• KPI: RRC Connection Drop Rate
• Counter: NR.CDR.RRCConnDrop
• Layer: RRC
• Why it matters: Tracks signaling stability. Frequent drops = configuration or coverage issues.
2. Bearer Retainability:
• KPI: Bearer Drop Rate (QCI-wise)
• Counter: NR.QCIx.BearerRelAbnorm
• Layer: PDCP / RLC
• Why it matters: Indicates QoS degradation and affects apps like VoNR and video.
3. Radio Link Failures (RLF):
• KPI: RLF Distribution by Cause
• Counters:
• NR.RLF.Cause.T310Expiry
• NR.RLF.Cause.ULSyncLost
• Layer: PHY/MAC
• Why it matters: Reveals physical layer issues like coverage holes or uplink weakness.
4. Handover Retainability:
• KPI: Post-HO Drop Rate
• Counter: NR.HO.FailPostHO
• Layer: Mobility
• Why it matters: Detects failures just after HO completion, often a root cause of session drops.
5. Session Continuity:
• KPI: Session Retention Success Rate
• Counter: NR.Bearer.RetainSuccessRatio
• Layer: User Plane
• Why it matters: Indicates end-to-end path success after mobility or transition.
🔍 How to Improve Retainability:
• 📶 T310 Expiry
• Fix: Lower T310 timer or improve DL signal quality
• Counter to Monitor: RLF.Cause.T310Expiry
• 📉 Handover Drops
• Fix: Adjust A3/A5 offsets, enable conditional HO
• Counter to Monitor: HO.FailPostHO
• 🔊 UL Power Issues
• Fix: Tune UL max power and control loops
• Counter to Monitor: RLF.Cause.ULSyncLost
• 🚫 QoS Bearer Drops
• Fix: QCI prioritization and buffering optimization
• Counter to Monitor: BearerRelAbnorm.QCIx
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� Case Snapshot – 5G SA (Urban Macro Layer)
• Issue: RRC retainability at 96.8% with high T310 expiry in edge zones
• Action:
• Activated conditional HO
• Optimized neighbor lists and reduced HO delay
• Increased Qrxlevmin to shrink poor-coverage serving footprint
• Result:
• RRC retainability ➝ 99.2%
• Bearer drops down 35%
• VoNR MOS scores stabilized
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✅ Why These KPIs & Counters?
Each reflects a unique failure point:
• RRC drop = config/signal issue
• Bearer drop = transport/QoS issue
• RLF = coverage/interference issue
• HO failure = mobility logic or timing
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