The headline is a rate over time, not a ratio of procedures: how often does a user abnormally lose a bearer per unit of holding time. Below it, four counter-level rates localize the loss. All formulas verbatim — the first from the Samsung eNB Counter Description (Retainability family, ch. 2 p. 1228), the rest from the operator reporting workbook.
| KPI | Family | Formula (Samsung counters) | Alert (deck) |
|---|---|---|---|
| ErabRetainability (official) | Retainability | SumRelActive ÷ RetainSessionTimeUE × 100 · per QCI: RetainRelActive ÷ RetainSessionTimeQci × 100 | <95% Critical |
| Call Drop Rate (%) | 24 CALL_DROP | CallDrop(all types Σ) ÷ (EstabInitSuccNbr + InterX2InSucc + InterS1InSucc) × 100 | >2% Major |
| E-RAB Drop Rate (%) | 15 ERAB_REL | RelActive ÷ (EstabInitSuccNbr + EstabAddSuccNbr) × 100 | abnormal >3% Major |
| RRC Abnormal Release Rate (%) | 4 RRC_RELEASE | (ConnRelease_RrcHcTo + ConnRelease_RrcSigFail + ConnRelease_RrcSigTo) ÷ SumRrcConnEstabSucc × 100 | >5% Minor |
| RRC Retention Rate (%) | — | 100 − RRC Abnormal Release Rate | — |
| RRC Reconfig Timeout Rate (%) | cross-family | (CallDrop_EccbTmoutRrcConnectionReconfig + ErabInfo_CallDrop_TmoutRrcConnectionReconfig + RelActive_EccbTmoutRrcConnectionReconfig) ÷ RrcRrcConnectionReconfiguration × 100 | — |
106): QCI-1 > 1% (VoLTE), others > 3% Major · Packet Drop (Fam 33 PDCP_DROP) > 1% Minor. The denominator of Call Drop Rate includes incoming handovers (InterX2InSucc + InterS1InSucc) — a cell that receives traffic it then drops is charged for it.Every counter in this page pegs after INITIAL CONTEXT SETUP RESPONSE — the call was successfully connected, then lost. The chain: the radio degrades → RLF detection (Family 105) → T310 runs → the UE attempts re-establishment (Family 3, the rescue) → rescued, or the eNB books the loss simultaneously in three ledgers: Call Drop (24), E-RAB Release (15) and RRC Release (4).
Samsung drop counters are CallDrop_Eccb<Cause> / RelActive_Eccb<Cause> / ConnRelease_<Domain><Cause>. The cause token names the failing layer — and therefore the team and the first place to look:
| Token | Layer / domain | What actually happened | First place to look |
|---|---|---|---|
RadioLinkFailure | PHY / MAC | HARQ ACK never came back after max retransmissions | Coverage, UL interference, UL/DL imbalance |
ArqMaxReTransmission | RLC | ARQ ACK not received after max RLC retransmissions | Air quality; enb/ue-max-retx-threshold |
TmoutRrcConnectionReconfig | RRC | ReconfigurationComplete timed out (often mid-handover) | Mobility params (a3-offset/TTT), t304 |
TmoutRrcConnectionReestablish | RRC | ReestablishmentComplete timed out — the rescue failed | t311, neighbour health, RLF-triggered HO |
DspAudit(Rlc/Mac)CallRelease | eNB internal | ECCB↔MAC/RLC audit mismatch — software/board state | Board alarms, SW version — not a radio parameter |
RcvResetRequestFromEcmb / RcvCellReleaseInd | System / cell ops | ECMB reset · cell state → disabled | Operations calendar — deliberate, exclude from tuning |
S1SctpOutOfService | S1 / transport | S1AP link left service — every call on it books a drop | Backhaul / MME SCTP — one event, mass drops |
Cp* / Up* / RrcSig* / S1ap* / X2ap* (Fam 4) | accessibility decoder | Same prefix grammar as the accessibility page — call control / protocol blocks / air / interfaces | Reuse the Day-2.1 decoder on release counters |
CallDrop_EccbRadioLinkFailure (24) + RelActive_EccbRadioLinkFailure (15) + CallDropQci_EccbRadioLinkFailure (106, per QCI) are one radio event read at call, bearer and QCI granularity. Diverging trends between ledgers = mix shift (which QCI is dying), not a new fault.The family (verbatim): "statistics for the call drop. Call drop statistics are calculated for successfully connected calls that abnormally dropped due to eNB failure or by the MME." Ten cause counters, indexed by CallDropEstabCause; Family 106 repeats all ten per QCI (plus the incoming-HO denominators ErabIncomingHoSuccNbr/AttemptNbr). All peg after INITIAL CONTEXT SETUP RESPONSE.
| Counter | Layer | Drop reason (verbatim) |
|---|---|---|
| CallDrop_EccbRadioLinkFailure | PHY/MAC | HARQ ACK not received after max retransmissions — the radio drop |
| CallDrop_EccbArqMaxReTransmission | RLC | ARQ ACK not received after max retransmissions |
| CallDrop_EccbTmoutRrcConnectionReconfig | RRC | RRCConnectionReconfigurationComplete timeout |
| CallDrop_EccbTmoutRrcConnectionReestablish | RRC | RRCConnectionReestablishmentComplete timeout — the rescue itself timed out |
| CallDrop_EccbS1SctpOutOfService | S1AP | S1AP link status changed to Out of Service |
| CallDrop_EccbDspAuditRlcMacCallRelease | RRC/MAC/RLC | Mismatch between ECCB and MAC/RLC during UE audit |
| CallDrop_EccbDspAuditMacCallRelease | MAC | Mismatch between ECCB and MAC during UE audit |
| CallDrop_EccbDspAuditRlcCallRelease | RLC | Mismatch between ECCB and RLC during UE audit |
| CallDrop_EccbRcvResetRequestFromEcmb | System | ECMB reset received |
| CallDrop_EccbRcvCellReleaseIndFromEcmb | Cell mgmt | Cell operational state changed to disabled |
| Dominant counter | Diagnosis | Technique / lever |
|---|---|---|
…RadioLinkFailure | Coverage / interference / UL imbalance | RF first (RSRP/SINR maps, tilt/power); then RLF timers t310 (1000→2000 ms deep-fade) + n310 (n1→n2), HARQ dl-max-harq-transmission 3→4 — use the T310 simulator below |
…ArqMaxReTransmission | RLC exhausts in poor-but-recoverable radio | enb-max-retx-threshold / ue-max-retx-threshold t8→t16 (adds latency — not for QCI-1); check UL interference |
…TmoutRrcConnectionReconfig | Reconfig lost mid-air — usually a mobility event | Read Family 26 first (too-late vs too-early vs wrong-cell); then a3-offset / time-to-trigger / hysteresis, t304 1000→2000 ms if execution-phase |
…TmoutRrcConnectionReestablish | The rescue is failing — recovery path broken | t311 5000→10000 ms, enable LTE-SW1014 RLF Triggered Handover, verify X2 to re-estab targets (see InterEnbConnReEstabReject_RlfHoNotPossible) |
…S1SctpOutOfService | Transport event — mass simultaneous drops | S1/backhaul health, SCTP paths, MME redundancy; s1-relocation-overall only if HO-release related — not a radio parameter |
…DspAudit* / RcvReset* | eNB software/board state, or planned ops | Board alarms, SW version, restart history; exclude maintenance windows from KPI baselines |
The family (verbatim): Family 15 counts "E-RABs released by the E-RAB Release Command message from MME to eNB, and the active E-RABs that are released abnormally" — RelActive is the numerator of both official retainability KPIs. Families 422/421 split every release by initiator (eNB vs MME) and normal vs abnormal, per QCI — the cleanest view of who ended the bearer and whether data was still flowing (…ActQci = data remained in the buffer).
| Counter | Initiator | Verbatim description |
|---|---|---|
| RelActive | eNB | Call releases due to an abnormal internal operation of the eNB in the setup E-RAB — the retainability numerator |
| RelActive_EccbRadioLinkFailure | eNB | Established E-RABs released — HARQ ACK never returned after max retransmissions |
| RelActive_EccbArqMaxReTransmission | eNB | Established E-RABs released — RLC ARQ exhausted |
| RelActive_EccbTmoutRrcConnectionReconfig / …Reestablish | eNB | Established E-RABs released — RRC reconfig / re-establishment timeout |
| RelActive_MmeInitErabRelease | MME | UE Context Release Command with abnormal CAUSE from MME, data still buffered |
| RelActive_ResetRelease | MME/eNB | Reset message from/to MME with buffered data — transport/core event |
| RelActive_ErabRelease | MME | E-RAB Release Command / Indication with abnormal cause |
| RelAttbyEnbNbr_CpCcTo / _S1apCuFail / _CpPreemption (Fam 14) | eNB→MME | eNB-requested releases via E-RAB Release Indication — incl. preemption |
| Counter | Initiator | Meaning |
|---|---|---|
| RelNormalbyEnbQci_UserInactivity | eNB · normal | Released by 'User Inactivity' cause — healthy behaviour, not a fault |
| RelNormalbyEnbQci_Pre | eNB · normal | Normal release by preemption policy |
| RelAbnormalbyEnbActQci | eNB · abnormal | Abnormal release with data remaining in the buffer — the true user-visible drop |
| RelAbnormalbyEnbActQci_RadioLinkFail / _TimeOut / _S1LinkFail / _S1Reset | eNB · abnormal | The abnormal-with-data split by cause — radio vs timers vs S1 |
| RelAbnormalbyMmeActQci (+_S1Reset, _EutranGen) | MME · abnormal | MME-initiated abnormal with buffered data; _EutranGen = cause originated in E-UTRAN |
RelAbnormalbyEnbActQci ÷ RelbyEnbQci per QCI. High on QCI-1 = VoLTE users hearing dead air → radio/mobility work. High RelAbnormalbyMme* = core-initiated (paging, S1, MME pool) → not a radio parameter. High RelNormal…UserInactivity with short session times = inactivity timer too aggressive → check ReleaseCntByTimer (Fam 333) and lengthen the inactivity profile before touching RF.Family 4 books every RRC connection release with a 25-way cause split using the same Cp/Up/RrcSig/S1ap/X2ap prefix grammar as accessibility. The abnormal-release KPI counts three of them: RrcHcTo (reconfig lost in intra-eNB handover), RrcSigFail, RrcSigTo. Family 3 is the counter-evidence of recovery: every re-establishment that succeeds is a drop that didn't happen.
| Counter | Domain | Verbatim description |
|---|---|---|
| ConnRelease_CpCcNormal | normal | Normal release — the healthy end of a call |
| ConnRelease_RrcHcTo | Air · mobility | ReconfigurationComplete not received during the intra-eNB handover — KPI counter |
| ConnRelease_RrcSigTo / _RrcSigFail | Air · UE | RRC response timeout / signalling failure after connection established — KPI counters |
| ConnRelease_UpMacUEInact | normal-ish | Released on inactivity timeout — policy, not fault |
| ConnRelease_UpMacFail / _UpRlcFail / _UpPdcpFail / _UpGtpFail | eNB boards | Failure between protocol block and ECCB — board/transport health |
| ConnRelease_S1apLinkFail / _S1apSigTo / _S1apRoTo / _S1apCuFail | S1 · MME | S1 link / signalling timeouts — core-facing releases |
| ConnRelease_CpPreemption | Admission | Released by preemption after setup — ARP policy in action |
| ConnRelease_MmeOverload | Core | Release sent because the MME is in overload state (LTE-SW0503 Overload Action) |
| Counter | Role | Verbatim description |
|---|---|---|
| ConnReEstabAtt | attempt | RRCConnectionRe-establishmentRequest messages received from the UE |
| ConnReEstabSucc | success | ReestablishmentComplete received — a drop prevented |
| ConnReEstabFail_UpMacFail / _UpPdcpFail / _UpRlcFail / _CpCcFail / _RrcSigTo / _S1ap* | fail | The rescue failed — same domain grammar; the failing layer names the fix |
| ConnReEstabReject_CpCcFail / _CpCapaCaccFail / _CpQosCacFail | reject | The eNB refused the rescue — CAC/capacity rejecting re-establishment |
| InterEnbConnReEstab* (12 counters) | inter-eNB | The UE re-establishes at a different eNB — needs UE context via X2 |
| InterEnbConnReEstabReject_RlfHoNotPossible | reject | Rejected because RLF Triggered Handover is OFF or X2 is missing — the feature gap, verbatim |
ConnReEstabSucc ÷ ConnReEstabAtt is your drop-recovery rate. Low with high Reject_Cp*CacFail = you are refusing rescues under load (review CAC for re-establishment). High InterEnbConnReEstabReject_RlfHoNotPossible = enable LTE-SW1014 + audit X2/NRT — the counter literally names the missing feature. Re-establishment success books the call as retained; every improvement here moves the drop KPI directly.Family 105 counts the raw physics: RlfDetection_RadioLinkFailure — "ECCB receives an OutOfSync notification from MAC" (verbatim) — and RlfDetection_ArqMaxReTransmission from RLC (plus EnDc_* twins for NSA anchors). Family 26 tells you why: the SON/MRO algorithm classifies each handover-related RLF.
| Counter | MRO verdict | Verbatim trigger | Standard fix direction |
|---|---|---|---|
| TooLateHoRlfBeforeTriggering / …AfterTriggering | Too-late HO | RLF before the A3 report / after the HO command was transmitted | Earlier trigger: ↓a3-offset, ↓time-to-trigger, CIO+ |
| TooEarlyHoFailure / TooEarlyHoRlfAfterHo | Too-early HO | Too-early handover after completing the handover process | Later trigger: ↑a3-offset, ↑TTT, CIO− |
| WrongCellRlfAfterTriggering / …AfterHo (+InterFreq) | Wrong cell | RLF received from a neighbour after HO completed (same-frequency target) | NRT audit, PCI confusion check, per-pair CIO |
| PingpongHandover | Ping-pong | Ping-pong conditions met by the detection algorithm | ↑hysteresis, ↑TTT on the oscillating pair |
| CoverageHole / CoverageHoleRsrp | Coverage hole | RLF/HO failure due to coverage hole based on SINR / RSRP | RF design: tilt/power/new site — parameters won't fill a hole |
mobility-robustness-enable (son-cell-info-func) to son-auto-apply and let it steer CIO per pair; the deck calls this "a significant optimization step". Voice twin: Family 353 MRO_RLF_VOICE repeats the classification for QCI-1 only — read it before touching VoLTE mobility.The entire RLF chapter compresses into four numbers. Drag the fade length and the timer values and watch the outcome flip between ride-through, rescued and dropped — then read which counters would peg. Model: out-of-sync indications arrive every 10 ms radio frame while the fade lasts (teaching model; deck-verbatim value sets).
Enter the busy-hour counters; the studio computes the three drop KPIs plus the rescue rate, grades each against the deck's alert bands, finds the weakest ledger, and the engine below ranks every drop cause into an action plan.
Every drop counter routed from its root-cause domain to the ledger where it pegs. Click a domain for its blast-radius, a ledger for everything that books there, a scenario for a cross-ledger signature — or any counter chip for its full optimization card.
Ten Samsung features from the deck's "Feature for Improving Call Drop Rate" table, ordered by role in the drop chain: harden the link, rescue the failure, move the UE in time, and protect the cell under load. Click any node for its full card.
Every retainability-relevant parameter from the Samsung LTE Retainability Optimization deck, grouped by function — MO source object, typical/default and the deck's recommended move with its caution. Ranges/defaults are the deck's stated typical values; always RTRV your release template first.
| Parameter | Typical | Deck recommendation | Caution |
|---|---|---|---|
| t310 | 1000 ms | Deep fades where UEs could recover → 2000 ms. Deck profiles: Rural/Highway 2000 · Urban dense 1000 · Indoor/Stadium 1500 · High-speed 500 | Too long delays true-failure detection and re-establishment |
| n310 | n1 | Temporary fades → n2 (less sensitive RLF detection) | Delayed RLF detection can mask other issues |
| n311 | n1 | Ping-pong RLF (recovers then fails again) → n2: require steadier recovery | Slower recovery declaration |
| t311 | 5000 ms | Re-estab failing on slow cell-search → 10000 ms | Very long keeps UE trying a bad frequency, delaying a fresh connection |
| t304 | ms1000 | HO-execution drops (target not ready) → 2000 ms | Too long delays recovery when HO is genuinely stuck |
| enb-max-retx-threshold / ue-max-retx-threshold (pld-rlc-info-func2) | t8 | RLF by RLC-max-retx in recoverable radio → t16 | Adds latency — not ideal for QCI-1/VoLTE |
| Parameter | Typical | Deck recommendation | Caution |
|---|---|---|---|
| a3-offset (eutra-event-a3-info-func) | 1–6 dB | Too-late HO → decrease (3→2/1 dB); ping-pong → increase (2→3/4 dB) | Monitor MRO Fam 26 after every move |
| time-to-trigger | 320/480/640 ms | Too-late HO → decrease (640→480/320); ping-pong → increase | Balance with a3-offset — short TTT + conservative offset often beats the reverse |
| hysteresis | 1–3 dB | Ping-pong → increase (1→2 dB); sticky serving cell → decrease | Works jointly with a3-offset and TTT |
| a5-threshold1-rsrp / a5-threshold2-rsrp | −110…−115 / −105…−110 dBm | Cell-edge drops before inter-freq HO → Th1 more aggressive (−110→−108); weak targets → Th2 more stringent (−110→−105) | Keep a 5–10 dB gap or the thresholds oscillate |
| s-measure (mobility-common-info-func) | ≈ −100 dBm | Late neighbour measurement on degrading serving → lower it (−100→−105/−110) | More measuring = more UE battery |
| q-hyst (cell-reselection-general-info-func) | 2 dB | Drops right after idle reselection + call start → 4 dB for stabler camping | Slower idle reselection |
| mobility-robustness-enable (son-cell-info-func) | — | son-auto-apply — MRO fixes too-early/too-late/wrong-cell automatically | Verify MRO statistics are collected and acted on |
| x2/s1-relocation-overall (timer-info) | 2–5 s / 2–10 s | "HO overall expiry" releases → increase slightly | Ties up source-eNB resources longer |
| no-handover (eutran-neighbor-cell-relation-info-func) · administrative-state | false / unlocked | Checks, not tuning: a barred pair or a locked neighbour = drops with no parameter cure | Critical after NRT updates / maintenance |
| Parameter | Typical | Deck recommendation | Caution |
|---|---|---|---|
| dl-max-harq-transmission (adaptive-modulation-coding-info-func) | 3–4 | RLF after DL HARQ NACK storms → 3→4 | Latency + resource cost per retransmission |
| max-harq-tx (ul-mac-config-info-func) | n4 | UL-driven RLF → n4→n5 | UL latency grows |
| p0-nominal-pusch (ul-common-phy-info-func) | −100…−80 dBm | Cell-edge UL SINR drops → +2…3 dB (e.g. −96→−93) | UL interference to neighbours, battery |
| alpha | 0.7/0.8/1.0 | Edge-UE drops → al1 (full pathloss compensation) | Fractional (0.7/0.8) manages interference better |
| time-alignment-timer-common | sf1280 | Drops preceded by UL-sync loss / RACH storms → sf2560 | Drift risk; with infinity ensure periodic TA works |
| tti-bundling (ul-mac-config-info-func) | false | Cell-edge VoLTE UL drops → enable (adaptive via ttib-in/out-tbs) | Capacity cost; VoLTE-focused |
| periodic-bsr-timer / retx-bsr-timer | sf640 / sf2560 | Slow UL grants at talk-spurt start → halve periodic (640→320) | More BSR = more UL signalling overhead |
| dl-target-bler / volte-dl/ul-target-bler | ~10% | Voice robustness → VoLTE BLER targets 1–5% (lower than data) | Costs capacity; >15–20% general BLER breeds RLF |
| Parameter | Typical | Deck recommendation | Caution |
|---|---|---|---|
| discard-timer (pld-pdcp-info-func, QCI-1) | 100–500 ms | Drops via PDCP discard in congestion → 150→300 ms | End-to-end delay — conversational quality |
| scheduling-type (qci-resource-info-func, QCI-1) | sps-scheduling | If dynamic → switch to SPS: regular low-latency voice allocation, deck calls it fundamental | — |
| implicit-release-after (sps-config-info-func) | e2/e4 | Glitches after silence periods → e2→e4 (keep SPS alive longer) | Wastes grants on long silences |
| rohc-context-continue | enable | Keep enable — avoids ROHC reset hiccups at intra-eNB HO | — |
| Parameter | Typical | Deck recommendation | Caution |
|---|---|---|---|
| preemption-enable / low-call-release-option (cell-cac-info-func) | use / longest-call | VoLTE preempted under load → ARP hygiene first; consider arp-based release policy | Preemption books into ConnRelease_CpPreemption — by design |
| qos-cac-option / qos-policy-option | qos-cac-use / option0 | option1 for granular GBR admission so bulk GBR can't starve QCI-1 | Align with ARP/preemption settings |
| check-ue-id-enable | use | Drops on S-TMSI duplication (existing call released) → consider no-use | MME-pool duplication handling shifts to the core |
| crsic-support-cell-conf (cell-phy-config-info-func) | HW-dependent | Dense grids with CRS interference → use (CRS-IC on) | Re-evaluate if a specific cell degrades after enabling |
| si-window (sib-control-info-func) | 20 ms | Transition-time drops with SIB acquisition suspicion → 40 ms | Longer full SI cycle |
| ra-response-window-size / contention-resolution-timer (rach-config-logic) | sf6 / sf48 | Recovery-RACH failing under load → sf8–10 / sf56–64 | Slower failure detection on genuinely missed preambles |
RTRV the live MO first, back up (*.bak convention), move one lever per soak, and verify on the owning family (24/15/4/3/105/26) plus the guards: re-establishment success (Fam 3) and HO success — a "retainability gain" that ships failures into mobility is a net loss.Baseline — pull all six families per cell
Busy hour: Families 24/106 (drops), 15/421/422 (E-RAB), 4 (releases), 3 (re-estab), 105/26 (RLF/MRO). Compute Call Drop Rate, E-RAB Drop Rate, RRC Abnormal Release Rate and the rescue rate.
Separate normal from abnormal
RelNormal…UserInactivity, ConnRelease_CpCcNormal/_UpMacUEInact, ReleaseCntByTimer, preemption and maintenance releases are policy, not faults. Compute the abnormal-with-data share (RelAbnormal…ActQci).
Rank the drop causes — the Pareto
Within Family 24 (and 106 for QCI-1), rank the ten causes (the engine above does this). The token names the layer: RLF=air · ArqMax=RLC · Tmout*=RRC/mobility · S1Sctp=transport · DspAudit=eNB internal.
cause token = layer = team If wrong: tuning timers on a cell whose top cause is S1 transport.Read the MRO verdict per neighbour pair
If Tmout…Reconfig or RLF dominates, open Family 26: too-late vs too-early vs wrong-cell vs ping-pong vs coverage-hole — per neighbour relation. Coverage holes get RF design, not parameters.
Apply ONE lever
Air → t310/n310 + HARQ/RLC depth (+ TTI bundling for VoLTE edge). Mobility → a3-offset/TTT/hysteresis or son-auto-apply MRO. Rescue → t311 + LTE-SW1014 + X2 audit. Transport/core → S1/MME with the evidence, not radio params.
one change per soak — attribute the gain If wrong: two levers at once = unattributable results.Soak & verify — same counters, same hour
The target cause must fall, its KPI must improve, and the guards must hold: rescue rate (Fam 3) up or stable, HO success stable, accessibility untouched. Check the same cause in ledgers 15 and 106 moved with it.
before/after on 24+15+4 · guards: 3, HO SR, Fam 1/8 If wrong: longer T310 "improves" drops while re-estab delay ruins user experience.Lock in — the VoLTE view
Re-read Family 106 for QCI-1 (>1% alert) and Family 353 MRO_RLF_VOICE; confirm SPS/discard-timer/BLER-target hygiene. Document the change and the counter evidence.
106 QCI-1 · 353 · SPS/discard-timer If wrong: the aggregate looks fixed while voice still drops.Retainability is one radio event, three ledgers, one diagnosis.
Drops per session-time, decomposed: Call Drop 24 · E-RAB 15 · RRC 4 — with Family 3 as the rescue and Family 26 as the witness. Decode the cause token, fix the owning layer. Then meet the same discipline in 5G.
Sources: Samsung eNB Counter Description (SLR 4.5 v7.0 — Retainability family formula p. 1228 verbatim; SLR 6.0) and the operator KPI workbook (LTE Samsung KPI.xlsx, "eNB Counters" sheet — Families 24 CALL_DROP, 106 CALL_DROP_QCI, 15 ERAB_REL, 14 ERAB_REL_ENB, 421/422 ERAB_REL by MME/eNB per QCI, 4 RRC_RELEASE, 3 RRC_REESTAB, 105 RLF_DETECTION, 26 MRO_RLF, 333 TIMER_RELEASE — counter names, descriptions and triggers verbatim) · Samsung LTE Retainability Optimization deck (alert thresholds, counter→reason→layer tables, parameter recommendations, feature table) · Troubleshooting Call Drop Failures deck · eNB (LTE) Feature Description (SVR24B — MO/parameter names). The SVR25A LTE Counter/Parameter Description originals are NASCA-DRM-locked; readable SLR equivalents were used. RLF procedure per 3GPP TS 36.331 §5.3.11. Targets marked "typical" are operator practice; counters, families and formulas are vendor-exact.