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4.1 · LTE · Throughput

LTE Throughput — Walk the Ladder, Then Pull the Levers

Throughput problems die from guessing which layer eats the bytes. Samsung instruments every layer of the stack — GTP at S1-U (ThruGtpDLEnbS1Nor), PDCP (PdcpIpThroughputDL), RLC (AirRlcDLThru + its retransmitted bytes), MAC at the air (AirMacDLThruAvg, with the workbook-verbatim effective formula), and IP per QCI (EnbQciDLThru) — so the drop between two adjacent layers names the culprit. Below the ladder sit the capacity levers: PRB (54/55), CQI/MCS distributions (50/62/63), HARQ retransmission histograms, CA (ca-available-type…), MIMO, scheduler, and the DRX latency triangle. Ladder → evidence → lever — every name verbatim.

5ladder layers DL+UL
54·55PRB per QCI · total
50CQI 0…15 histogram
62·63MCS distribution
Retrans0-6HARQ histogram
16feature pipeline
The formulas — effective MAC throughput and the peak-rate anatomy
Verbatim formulas
KPIFormulaSource
Cell MAC DL Effective Throughput (kbps)(AirMacByteDl × 8) ÷ AirMacTtiDl × 1000workbook, verbatim — bytes over scheduled TTIs only (that's what "effective" means)
Cell MAC UL Effective Throughput (kbps)(AirMacByteUl × 8) ÷ AirMacTtiUl × 1000workbook, verbatim
Peak throughput (Mbps)RBs × 12 × 14 × bits/symbol × code-rate × MIMO-layers × 1000 ÷ 10⁶deck, verbatim — then × efficiency factor 0.7–0.9
The RB table1.4 MHz = 6 · 3 MHz = 15 · 5 MHz = 25 · 20 MHz = 100 RBs; QPSK 2 · 16QAM 4 · 64QAM 6 · 256QAM 8 bits/symbol; code rate 0.076–0.948deck, verbatim
Effective vs average — AirMacDLThruAvg divides by wall-clock; AirMacDLEfctivThruAvg divides by TTIs actually scheduled. A cell with low average but high effective throughput isn't slow — it's idle. Always read the pair before diagnosing.
The five-layer ladder — where do the bytes die? (deck-verbatim counters)

One table per direction in the deck; condensed here. The rule: compare adjacent layers — a healthy stack loses almost nothing between rungs. The first big gap names the layer, the layer names the fix:

The DL ladder (UL twins: swap DL→UL)
RungCounters (verbatim)A gap below this rung means…
1 · GTP (S1-U in)ThruGtpDLEnbS1Nor/Tot/Cnt · ByteGtpDLEnbS1Nor · CntGtpDLEnbS1NorNothing below — this is what the core delivers. Low here = backhaul/core/S-GW, not radio
2 · PDCPPdcpIpThroughputDL · PdcpVolDlByte · PdcpTimeDl · PdcpSduBitrateDLAvg/Tot/CntGTP→PDCP gap = traffic control / buffering (CellTcDLDrop*, Fam 322) or PDCP discard (discard-timer)
3 · RLCAirRlcDLByte · AirRlcDLThru · AirRlcDLByteRe (retransmitted!)PDCP→RLC gap = RLC buffer; high ByteRe share = the air is eating retransmissions (go to CQI/BLER)
4 · MAC (air)AirMacDLByte · AirMacDLThruAvg · AirMacDLEfctivThruAvg · AirMacDLTtiRLC→MAC gap = scheduler starvation (PRB, PDCCH/CCE) — the capacity levers live here
5 · IP per QCIEnbQciDLByte · EnbQciDLThru/Max/Min · PacketDLCntThe per-service truth — one QCI starving while the cell is fine = QoS weights, not capacity
The evidence counters — PRB · CQI · MCS · HARQ (deck-verbatim)
The four evidence sets
SetCounters (verbatim)How to read it
PRB (54/55)TotPrbDLAvg/Min/Max · TotGbrPrbDLAvg · TotNGbrPrbDLAvg · PrbDLAvg (per QCI) · UsedPrbDLNum · AvailablePrbDLNum + UL twins (UsedPrbPUSCHNum…)The load axis: <20% idle · 20–70% RF-quality territory · >70% congestion · >90% severe (the NR deck's bands apply here too)
CQI (50, + 238/239 per P/SCell, 419 for 256QAM)DLReceivedCQI0…CQI15 · DLReceivedCQIAvg/Min/MaxThe quality histogram: mass below CQI-7 = RF work (interference/coverage), not parameters
MCS (62/63, 418 for 256QAM)DL/UL MCS distribution countersMCS ceiling vs CQI: good CQI + low MCS = link-adaptation or BLER-target too conservative
HARQ (deck tables)DLTransmissionRetrans0…6 · DLResidualBlerRetrans0…6 · UL twins (…0…27) · DLVoLTEHARQFail/Succ/FailRateThe retransmission histogram: mass beyond Retrans1 = air quality; residual BLER at max = packet loss reaching RLC
!
The order is the method — PRB first (is there congestion or idleness?), CQI second (is the air any good?), MCS third (is the scheduler using the air?), HARQ fourth (is it surviving?). Jumping straight to parameters without the four-set read is how networks end up with 256QAM enabled on a CQI-5 cell.
Interactive — the throughput-ladder localizer

Enter the per-layer throughputs from the ladder counters plus the evidence; the localizer finds the biggest inter-layer gap, reads the evidence, and names the lever.

Throughput Ladder Localizerlive
The ladder (Mbps, busy hour)
The evidence
Biggest ladder gap
Carrier aggregation — the multiplier (deck-verbatim tuning)
CA levers (deck table, condensed verbatim)
LeverTypicalDeck guidance
ca-available-type (ca-cell-info-func)dl-and-ul / dl-only"The fundamental enabling parameter" — verify licensing; ca-off = no CA, full stop
max-dl-ca-cc-num2…5Set to the highest supported — "a higher number of CCs directly translates to higher potential peak DL throughput"; ensure the backhaul can carry it
ca-operation-modemode-4"The most flexibility for SCell addition/activation based on need" — traffic + measurements
A4 SCell thresholds (a4-threshold-rsrp/rsrq, purpose=ca)plan"Make A4 less stringent if SCells are underutilized"; monitor Time-to-SCell-Add and SCell utilization %
Evidence families233 CA_UE_CAPABILITY (who can) · 235/270 ACT_DEACT/ADD_REL (what happened) · 335 CA_UE_PER_CC_NUM (how many CCs) · 237/239 SCell MAC bytes/CQI (what it yielded) · 492 CA_PDCP_PACKET · 936 PCC_FOR_CA
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The CA audit chain — capable (233) → configured (270) → activated (235) → used (237 SCell bytes). Each stage loses UEs; find the biggest loss. Capable-but-never-configured = A4 too strict; activated-but-idle = traffic model or scheduler (ME3314 unified PF for CA).
DRX & latency — the perception lever (deck-verbatim triangle)
The DRX triangle (battery / latency / balanced — deck values verbatim)
ParameterBatteryLatencyBalanced (deck starting point)
on-duration-timer-normalpsf4psf10psf6–psf8 — "long enough to reliably decode PDCCH"
drx-inactivity-timer-normalpsf10psf100psf20–psf40 — "crucial for latency/throughput perception… improves page load times"
long-drx-cyclesf1280sf320sf640/sf1280 — the compromise
short-drx-config-setupenable bothenable — "better responsiveness… while still saving power"
Why DRX is on the throughput page — bursty traffic (web) experiences throughput as latency: a UE asleep at the burst start loses the first RTTs. The deck's inactivity-timer guidance (20–40 ms) is a perceived-throughput lever that costs zero PRBs. Evidence: IP_LATENCY (Fam 35) and PDCP_DELAY (36) — plus the DL/UL IP throughput distributions (Fams 345/346) for the user-experience histogram.
The throughput feature pipeline — 16 features, deck-verbatim (DL + scheduling/link-adaptation)
LTE Throughput Feature Pipelineclick a feature node to open its detail card
The throughput parameter groups (deck chapters, key rows)
Grouped levers (deck values; full detail lives in the deck's 20+ tables)
GroupKey leversDirection
Link adaptationdl-target-bler ~10% (VoLTE 1–5%) · cqi-filtering-coeff (responsiveness vs stability) · CQI correction (ME3205) · aperiodic CQI (ME3203)MCS honesty — the CQI→MCS chain
HARQdl-max-harq-transmission 3→4 · max-harq-tx n4→n5Depth vs latency (shared with retainability — the drop view lives there)
UL powerp0-nominal-pusch +2–3 dB edge · alpha 0.8↔1.0 · tti-bundling for edge VoLTEUL SINR at the edge — UL ladder rung 4
Scheduler / PDCCHFrequency-selective scheduling (ME3306) · PF weights · CCE/PDCCH capacity (deck PDCCH chapter) · SCHE_UE_NUMBER (438) as the evidenceRLC→MAC gap killers
Buffers / BSRperiodic-bsr-timer sf640→sf320 · retx-bsr-timerUL grant latency at talk-spurt/burst start
Load balancingThe full MLB stack — on the mobility page (equal-threshold/delta, idle steering) — throughput's biggest lever is often moving the loadcross-page
The 6-step LTE throughput MOP
1
Walk the ladder

All five rungs, both directions, busy hour. Find the biggest adjacent-layer gap — that's the working layer. Read effective vs average MAC first (idle ≠ slow).

GTP → PDCP → RLC → MAC → IP Skip this and you tune radio for a backhaul problem.
2
Read the four evidence sets in order

PRB (load) → CQI (air quality) → MCS (is the scheduler using it) → HARQ histogram (is it surviving). The combination names the branch.

PRB · CQI · MCS · HARQ If wrong: 256QAM on a CQI-5 cell.
3
Branch by the PRB bands

<20%: is the requirement even unmet? · 20–70% + low thpt: RF quality work · >70%: scheduler/capacity · >90%: congestion pack + MLB (mobility page).

the PRB decision bands If wrong: capacity spend on an interference problem.
4
Audit the multipliers

CA chain: capable→configured→activated→used (find the biggest loss). MIMO: rank usage vs capability (Fam 61/357). 256QAM: CQI table support (418/419).

CA/MIMO/QAM audit chains If wrong: peak features idle while the basics starve.
5
Apply ONE lever

RF branch: interference/tilt + link adaptation. Scheduler branch: ME3306/PF/PDCCH. Congestion: MLB + CAC + congestion MCS. Perception: the DRX triangle.

one lever per soak If wrong: unattributable results.
6
Verify on the ladder + guards

The gap must close where you worked; QCI-1 HARQ (VoLTE) held; drops (retainability page) and HO SR (mobility page) untouched; per-QCI IP view (rung 5) confirms users felt it.

same hour, ladder before/after If wrong: a MAC gain that PDCP discards is invisible to users.

LTE throughput is a ladder walk, four evidence sets, one lever.

The gap names the layer, the evidence names the branch, the branch names the lever. Continue to the 5G twins — the split bearer and the PRB playbook.

Sources: Samsung eNB Counter Description via the operator KPI workbook (the MAC effective-throughput formulas verbatim; Families 30 CP_PACKET, 35/36 latency/delay, 50 DL_CQI, 54/55 PRB, 61 MIMO, 62/63 MCS, 233/235/237/239/270/335/352/357/386/418/419/440/492/936 CA set, 322 traffic control, 328/329 SPS, 345/346 IP-throughput distributions, 438 SCHE_UE_NUMBER — names verbatim) · Samsung LTE Throughput Optimization deck (the five-layer DL/UL counter tables, PRB/CQI/HARQ tables, CA tuning table, DRX settings table, the DL feature-trial tables LTE-ME2019/2023/2022/5801/5801-A/5870-A/4003/4005 and ME3306/3314/3312/3325/3205/3201/3203/3305 — all verbatim; peak-throughput formula and RB anatomy verbatim). Load-balancing parameters live on the LTE mobility page; the HARQ/BLER drop view on the LTE retainability page — cross-referenced, not duplicated.