03
3
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Day objective — reliable connected-mode mobility (fewer ping-pongs / late HOs) and correct idle-mode reselection. Every parameter below shows its exact Samsung default (SVR22B NR) and a recommended tuning value.
3.1
Connected-Mode Mobility (LTE & NR)
Every handover mechanism you tune — the measurement events that trigger a report, the HO types, target-cell selection, CHO, ANR, and the golden parameters behind them.
Measure → event trigger → report → HO decision → executeTS 38.331
the event + TTT decide whenCHO pre-configures the target so execution needs no live report.
Measurement events — what each one means
NR / LTE measurement events (TS 38.331)
| Event | Condition | Used for |
|---|---|---|
A1 | Serving becomes better than threshold | Stop inter-freq measurement / deactivate |
A2 | Serving becomes worse than threshold | Start measurement / coverage trigger |
A3 | Neighbour becomes offset better than serving | Intra/inter-freq HO (the workhorse) |
A4 | Neighbour becomes better than threshold | Load-balancing HO |
A5 | Serving worse than thr1 AND neighbour better than thr2 | Coverage HO (Samsung default intra-NR trigger) |
B1 / B2 | Inter-RAT neighbour good (B1) / serving poor & inter-RAT good (B2) | NR↔LTE, EPS Fallback |
★
- LTE mobility — HO legs 17/18/20 · trigger layer · idle/paging · MLB · A3 visualizer
- 5G NSA (EN-DC) mobility — PSCell change 5109/5110 · anchor choreography · move explorer
- 5G SA mobility — Xn/NG legs · idle rules (MC1006) · EPS fallback · reselection calculator
- Load Balancing deep-dive — L2600 ⇄ L1800 · composite load metric (load-prb/load-total) · CCCV formula · mixed-model decision + live calculator · every LTE-SW20xx feature
HO golden parameters — Default (exact) vs Recommended
Handover / measurement (real MO · SVR22B NR)
| Parameter | Range | Default | Recommended | Purpose |
|---|---|---|---|---|
| intra-nr-handover-event-type | a3 / a5 | event-a5 | a5 (coverage) / a3 (dense) | Primary intra-NR HO trigger |
| a3-offset-rsrp | −30…30 | 4 | 4–6 | Neighbour-better margin (0.5 dB step) |
| a3-hysteresis | 0…30 | 0 | 1–2 | Anti-ping-pong hysteresis |
| time-to-trigger | ms0…ms1024 | ms40 | ms160–320 | Report debounce — the #1 ping-pong lever |
| a5-threshold1-rsrp | 0…127 | 51 | per coverage | Serving-worse-than (≈ −105 dBm) |
| a5-threshold2-rsrp | 0…127 | 51 | per coverage | Neighbour-better-than |
| b1-threshold-eutra-rsrp | 0…97 | 51 | per plan | Inter-RAT NR→LTE trigger |
| report-interval | ms120…min60 | ms240 | ms240 | Periodic report interval |
| report-amount | r1…infinity | r2 | r2 | Reports per trigger |
≡
RSRP index — the 0–127 value maps to −156…−31 dBm, so
a5-threshold1 = 51 ≈ −105 dBm. To fix late HO raise A3-offset / A5-thresholds or cut TTT; to fix ping-pong raise TTT (ms40→ms160–320) and add A3 hysteresis. HO types, CHO & ANR
Intra-freq HOInter-freq HONR↔LTEEPS FallbackConditional HO (CHO)Follow-A2 · service-border
CHO & ANR parameters (real MO)
| Parameter | Range | Default | Purpose |
|---|---|---|---|
| number-of-cho-candidate-cell | 0…8 | 0 | Pre-configured CHO targets (0 = CHO off) |
| anr-switch | off / on | on | Automatic Neighbour Relations (auto NRT) |
| max-number-retransmission (ANR) | 0…3 | 2 | Unknown-PCI report retransmission cap |
| sa-frequency-priority | 0…31 | 0 | Connected-mode target-frequency priority |
Counters & KPIs
Mobility KPIs
| KPI | Formula | Target |
|---|---|---|
| HO Success Rate | HO Success ÷ HO Attempt × 100 | ≥ 98–99 % |
| Ping-pong rate | HO back to source < T ÷ total HO | low → raise TTT / hysteresis |
| Intra vs inter-freq HO SR | per HO type | diagnose by type |
| ANR new-neighbour adds | detected PCIs → NRT | stabilises after rollout |
i
SVR25A / SVR25B add newer mobility features (per-PLMN mobility, richer CHO) — treat each as a golden-parameter change to trial (Day 6).
3.2
Idle-Mode Optimization
Where the UE camps and how it reselects — the SIB map, the reselection R-criteria, the priority/hysteresis/timer golden parameters, plus speed scaling and relaxed measurement.
The SIB map — which SIB carries which reselection infoidle camping
UE reads its SIBsReselect to neighbour when Rn > Rs for
t-reselection; priorities override ranking. Idle / reselection golden parameters — Default vs Recommended
cell-reselect-intra-freq-info (real MO · exact defaults)
| Parameter | Range | Default | Recommended | Purpose |
|---|---|---|---|---|
| cell-reselection-priority | 0…7 | 5 | per layer / PLMN | Absolute frequency priority (load steering) |
| q-hyst | dB0…dB18 | dB1 | dB2–4 | Reselection hysteresis (anti-churn) |
| t-reselection-nr | 0…7 s | 1 | 1–2 | Reselection timer |
| threshold-rsrp | 0…127 | 35 | per coverage | Serving RSRP gate |
| threshold-rsrq | 0…127 | 8 | per coverage | Serving RSRQ gate |
| s-search-threshold-p | 0…31 | 0 | per plan | When to start inter-freq/RAT search |
| nr-of-ss-blocks-to-average | 2…16 | 2 | 4–8 | SSB averaging for measurement stability |
Speed scaling & relaxed measurement
A fast-moving UE crosses cells quickly, so Samsung scales reselection by mobility state — count cell changes over an evaluation window to classify Normal / Medium / High mobility and shorten timers accordingly. Relaxed measurement lets a low-mobility / cell-centre UE measure less to save battery.
speed-state-reselection-pars & relaxed measurement (real MO)
| Parameter | Range | Default | Purpose |
|---|---|---|---|
| t-evaluation | s30…s240 | s60 | Window to count cell changes |
| t-hyst-normal | s30…s240 | s60 | Time to drop back to Normal state |
| n-cell-change-medium | 1…16 | 5 | Cell changes → Medium-mobility state |
| n-cell-change-high | 1…16 | 10 | Cell changes → High-mobility state |
| relaxed-measurement-mode | off / low-mob-&-cell-edge / … | low-mobility-and-cell-edge | When the UE may relax measurements |
!
Idle balances against connected — reselection priorities and IFLB (Day-5
LC0702) steer idle camping; set priorities per layer so idle UEs pre-distribute before they ever connect, but keep q-hyst / t-reselection high enough to avoid idle churn at cell edges.LAB
Hands-on Lab 3 — Handover & Reselection Tuning
Cut ping-pong and fix late handovers with measurement-event tuning, then correct camping behaviour with a cell-reselection priority exercise.
Hands-on Lab 3
Cut ping-pong / fix late HO · reselection priority tuning
⚡- 1Baseline HO Success Rate and ping-pong ratio from counters
- 2Ping-pong fix — raise
time-to-trigger(ms40→ms160) + adda3-hysteresis1–2 - 3Late-HO fix — raise A3-offset / A5 thresholds so HO fires earlier
- 4Reselection tuning — set
cell-reselection-priorityper layer; raiseq-hystto stop idle churn - 5Verify HO SR up, ping-pong down, no drop-rate regression
TTTA3 offset/hystA5 thresholdsreselection-priorityq-hyst
Deliverable — a tuned mobility profile with measured ping-pong reduction and stable HO success rate.