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Course/Day 2/Accessibility & Retainability
02
2
Day Two

Accessibility & Retainability Optimization

Get UEs onto the network reliably and keep them connected — RRC/RA setup, admission control, and drop / RLF reduction, with the exact Samsung Family IDs, FGR features and real golden-parameter values.

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Day objective — reliable access (RRC / RA / admission) and strong retainability (drop & RLF reduction), tuned via golden parameters. Pick a sub-topic on the left — it opens here on its own.

2.1

Accessibility KPIs (LTE & NR)

Accessibility is a chain — every stage from random access to bearer setup has its own Samsung KPI and Family ID. A failure at any link drops the end-to-end setup success.

The access chain — each stage carries its own Samsung Family IDRA → RRC → context → bearer
UE idle
RRC_IDLE
Random Access
Msg1–Msg4 RACH
RA SR · 5243
RRC setup
Conn Establishment
SR 5213 · time 5214
Initial context
Init Ctx Setup
SR 5223 / 5224
Bearer
E-RAB / DRB / PDU
5118 · 5218 · 5222
a break at any stage lowers end-to-end accessibilityNR adds the F1 UE Context Setup (5136/5137) across the DU↔CU split.
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Technology deep-dives — accessibility differs by radio technology. Each page below is fully wired — the access chain, every KPI & formula, the real counters and the optimization playbook — for LTE, 5G NSA and 5G SA separately.LTE ›5G NSA ›5G SA ›
Full accessibility KPI set with Samsung Family IDs
Accessibility KPIs (LTE & NR)
KPISamsung Family IDStage
RRC Connection Establishment SR5213RRC setup
RRC Setup Time5214RRC setup
RRC Resume SR5217INACTIVE→CONNECTED
RRC Re-establishment SR5203recovery
Initial Context Setup SR5223 / 5224context
F1 UE Context Setup SR5136 / 5137DU↔CU (NR)
E-RAB / DRB / PDU-Session Setup SR5118 / 5218-5219 / 5222-5438bearer
Random Access Success Rate5243RACH
Admission Control Fail Rate5147 / 5148admission
  • Accessibility KPIs (LTE & NR) — unified family map · KPI Explorer · deep-dive hub
  • LTE accessibility — full KPI · counter · optimization deep-dive
  • 5G NSA (EN-DC) accessibility — SgNB Addition deep-dive
  • 5G SA accessibility — RRC/Registration/PDU deep-dive
  • RRC Connection Establishment SR — Family 5213; RRC Setup Time — 5214
  • RRC Resume SR — 5217; RRC Re-establishment SR — 5203
  • Initial Context Setup SR — 5223 / 5224
  • F1 UE Context Setup SR — 5136 / 5137
  • E-RAB / DRB / PDU-Session Setup SR — 5118 / 5218-5219 / 5222-5438
  • Random Access Success Rate — 5243
  • Admission Control Fail Rate — 5147 / 5148
2.2

Accessibility Features & Golden Parameters

The FGR features that govern access, and the golden-parameter groups you tune to move the accessibility KPIs — shown with their real Samsung managed-object leaf, range and default from the Parameter Description.

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Full feature catalog — all 43 access features for LTE, NR SA and NSA as a clickable React-Flow pipeline plus the golden-parameter master tables.Open the feature catalog ›The method ›
The method in one wire — feature governs → parameter tunes → counter proves

Every accessibility fix is this chain: an FGR feature owns a gate, a golden parameter (kebab-case, with its MO path) tunes it one variable at a time, and a counter Family ID proves the result after a 48 h soak. The console below turns any golden parameter into a full Format-A tuning card.

FGR feature → golden parameter → counter Family IDsingle variable
FGR-RS0121/0122
RACH · governs Stage 0
FGR-CC0102
RRC re-establishment
FGR-CC0301
capacity CAC
preamble-trans-max
…/prach-config
t311
…/ue-timer-constants
call-cac-threshold
…/cac-info
Family 5243
RACH SR (per beam)
Family 5203
Re-establishment SR
Family 5147/5148
Admission Fail
feature owns the gateparameter tunes it (one variable) · counter proves it (48 h soak, roll back if degraded)
Golden-Parameter Optimization Console — Format A · RAT-wise (LTE · NR SA · NSA)

Golden parameters are RAT-specific — the same KPI is tuned by a different managed-object leaf in each technology. Pick a RAT, then a parameter; the console renders its full Samsung Format-A card: MO path, doc-exact default, Samsung-recommended value, tuning range, KPI impact, the FGR/LTE-SW feature, the counter Family IDs to watch before/after, a single-variable trial plan, and the rollback trigger. LTE leaves & timer defaults verbatim from the eNB Parameter Description SSLR 9.0.0; NR from the DU SVR22B / CU-ACPF SVR25A descriptions; NSA (EN-DC) from the LTE-anchor eutra-nr-dual-connectivity tree.

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Confidence — MO leaf names, ranges and defaults are Certain (Samsung Parameter Description); recommended target values are Likely Samsung optimization guidance, to be confirmed against the Recommended Configuration for your SVR release before rollout. These doc-exact defaults supersede older catalog values (e.g. t310 ms2000 not ms50, preamble-trans-max n10 not n4, ssb-per-rach-occasion one not one-fourth).
  • Method — feature (FGR) governs the gate · one kebab-case parameter tunes it · counter Family ID proves it after a 48 h soak · roll back if degraded
  • FGR features — CC3102 access · CC0301/0302/0303 capacity/QoS/slice CAC · CC0102 re-establishment · CC0103/0107/0108 Inactive · RS0121/0122 RACH · LC0303/LC0401 overload
  • Golden params — RRC timers t300/t301/t304/t310/t311/t319 · RACH preamble-trans-max, power-ramping-step, ra-contention-resolution-timer, msg1-fdm, ssb-per-rach-occasion · admission call-cac-threshold, preemption-trigger-arp-priority
2.3

Retainability Optimization

Keep established connections alive — call-drop and RLF KPIs, and a structured root-cause workflow that sorts every drop into one of four causes before you touch a parameter.

Drop root-cause decision — classify before you tune4-way split
Drop / RLF event
from counters
Coverage
RSRP / SINR floor
Interference
neighbour / PCI
Mobility
late / wrong HO
Capacity
admission / preempt
Targeted golden param
RLF/RRC · preempt · HO
classify the drop firstthen apply the golden parameter that matches the cause — never blind-tune.
  • KPIs & counters — call-drop and Radio Link Failure (RLF) KPIs and counters
  • Drop root-cause workflow — coverage vs interference vs mobility vs capacity
  • Golden params · Retainability — RLF + RRC timers, admission-preemption, mobility-related drop settings
  • LTE retainability — Call Drop 24 · E-RAB 15 · RRC 4 · RLF/MRO deep-dive with T310 simulator
  • 5G NSA (EN-DC) retainability — SCG Failure & SgNB Release dual-ledger deep-dive
  • 5G SA retainability — DRB/UE-context release & two-path rescue deep-dive
★
Technology deep-dives — retainability differs by radio technology. Each page below is fully wired — the drop chain, every KPI & formula verbatim, the real drop-cause counters, interactive simulators and the optimization playbook — for LTE, 5G NSA and 5G SA separately.LTE ›5G NSA ›5G SA ›
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Coupling — t310 (Day-2 accessibility) is also the primary retainability lever: shorten it and you recover faster but risk dropping recoverable links; lengthen it and you hold links longer but delay re-establishment. Retainability and accessibility are tuned together, never in isolation.
LAB

Hands-on Lab 2 — Accessibility Trial & Call-Drop Reduction

Run a controlled accessibility trial by tuning RACH / RRC timers, then work a real call-drop reduction case straight from the counters.

Hands-on Lab 2

RACH / RRC timer trial · counter-driven call-drop reduction

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  • 1Baseline the accessibility KPIs (RRC Est SR 5213, RA SR 5243) from the counters
  • 2Run an accessibility trial — tune RACH / RRC timer golden parameters (e.g. t300, preamble-trans-max)
  • 3Work a call-drop reduction case using the RLF / drop counters and the 4-way root-cause workflow
  • 4Verify the KPI movement and document before/after
RRC timersRACH paramsRLF counters
Deliverable — a before/after accessibility & retainability KPI comparison from a single controlled change.