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NTN & Direct-to-Device: 5G from Orbit
The satellite link taught as arithmetic, not architecture — slant range and delay you can compute, a link budget that closes in both directions, the pre-compensation a handset owes before it may transmit, and the mobility a moving cell forces on a network built for stationary ones.
What you'll learn
- Turn “high and fast” into quantities: the three frames NTN stretches, and slant range and delay computed from an elevation angle.
- Weigh what an orbit buys and charges, place the gNB in a transparent or regenerative payload, and close a link budget in both directions.
- Work out what a UE must hold before it may transmit, what it pre-compensates itself, and what breaks when timing advance and HARQ stretch.
- Hold the earth-fixed and earth-moving cell taxonomy exactly, and account for what a moving cell does to mobility, identity and signalling load.
- Separate the spectrum routes to orbit, size what one beam honestly carries, and read the release train for which capability is actually specified.
Module 1 — From 'high and fast' to a number you can compute
4 lessons · 2 lab · ≈29 minTurn “high and fast” into quantities: the three frames NTN stretches, and slant range and delay computed from an elevation angle.
Module 1 — From 'high and fast' to a number you can compute
4 lessons · 2 lab · ≈29 minTurn “high and fast” into quantities: the three frames NTN stretches, and slant range and delay computed from an elevation angle.
- 17:06Slant range, delay, Doppler and moving cells: what "high and fast" actually costsWatch free
- 27:30The standards lane and the product lane: one ladder, two railsFree with an account
- 37:00Timing advance, HARQ and Doppler: the three frames this course stretchesFree with an account
- 47:03Slant range from elevation angle: the first number you can computeFree with an account
- ~5 minHigh, or Fast?Checkpoint
Seven satellite difficulties, two properties, and one mechanism whose two halves land in different columns. File each symptom under the property that actually causes it.
- ~6 minHow Far Is It Really?Interactive lab
Turn the handle on the geometry lesson's triangle. Find the overhead sanity check, stop at the mask to reproduce the published maximum to the kilometre, then work out from range and altitude alone the angle where the path doubles — which the video never states.
Module 2 — Geometry, payloads and the budget that decides the service
5 lessons · 2 lab · ≈40 minWeigh what an orbit buys and charges, place the gNB in a transparent or regenerative payload, and close a link budget in both directions.
Module 2 — Geometry, payloads and the budget that decides the service
5 lessons · 2 lab · ≈40 minWeigh what an orbit buys and charges, place the gNB in a transparent or regenerative payload, and close a link budget in both directions.
- 18:22LEO, MEO and GEO: what altitude buys and what it chargesRequires subscription
- 28:13Transparent and regenerative payloads: where the gNB sitsRequires subscription
- 38:43EIRP, G/T and path loss: the downlink budget that closesRequires subscription
- 47:21The uplink budget: why the handset is the weak endRequires subscription
- 57:40From carrier-to-noise to service class: what the budget lets you promiseRequires subscription
- ~6 minWhich Legs Did You Measure?Checkpoint
Five cases, one reference geometry, and two round-trip figures a factor of two apart. Two cases can be answered with one of them; three cannot, each for a different reason.
- ~7 minWhich Direction Binds?Interactive lab
Two budget columns from the same geometry, and one term on the ledger that is not fixed. Find the binding direction, the lever that rescues it, and the wall the lever cannot get through.
Module 3 — Making the radio work at 600 km
6 lessons · 2 lab · ≈51 minWork out what a UE must hold before it may transmit, what it pre-compensates itself, and what breaks when timing advance and HARQ stretch.
Module 3 — Making the radio work at 600 km
6 lessons · 2 lab · ≈51 minWork out what a UE must hold before it may transmit, what it pre-compensates itself, and what breaks when timing advance and HARQ stretch.
- 18:14GNSS, ephemeris and epoch time: what a UE must hold before it may transmitRequires subscription
- 28:54Doppler pre-compensation: the UE owns the service linkRequires subscription
- 38:34Timing advance in four terms: open-loop pre-compensationRequires subscription
- 48:30Random access over a satellite link: the first thing that breaksRequires subscription
- 58:42HARQ and every closed loop at one round tripRequires subscription
- 68:14Repetition and coverage: buying margin without feedbackRequires subscription
- ~7 minWho Supplies This?Checkpoint
Three facts a handset lacks at power-on, and the timing terms and frequency corrections that follow from them. Sort each by who actually supplies it — and find the two that pay for no leg of this link at all.
- ~7 minPick the RepairCheckpoint
Six proposals from six real conversations. One is the repair, some are the right diagnosis with the wrong fix, and some are aimed at something that was never broken.
Module 4 — Cells that move, and the network that follows them
6 lessons · 2 lab · ≈48 minHold the earth-fixed and earth-moving cell taxonomy exactly, and account for what a moving cell does to mobility, identity and signalling load.
Module 4 — Cells that move, and the network that follows them
6 lessons · 2 lab · ≈48 minHold the earth-fixed and earth-moving cell taxonomy exactly, and account for what a moving cell does to mobility, identity and signalling load.
- 17:50Earth-fixed, quasi-earth-fixed and earth-moving cellsRequires subscription
- 28:17Service link switch, feeder link switchover and satellite switchRequires subscription
- 38:21Conditional handover on distance and time: the NTN trigger eventsRequires subscription
- 48:31NTN-to-TN handover: coverage broadcast, ephemeris on the ground, entry without random accessRequires subscription
- 57:40Mapped Cell ID and core selection: a cell that crosses a borderRequires subscription
- 67:11Regenerative operations: gNB on board and inter-satellite linksRequires subscription
- ~6 minWhat Does the Trace Show?Checkpoint
Six events in a moving constellation, and the four conditions from the lesson. Say what each one arrives as in your trace — and whether the case everyone quotes survives it.
- ~6 minJudge the ClaimCheckpoint
Seven sentences about a network that follows its own moving cells. None of them is careless. Say which survive as said, which need a condition put back, and which are not the case.
Module 5 — What is flying, what is specified, and what to track
6 lessons · 2 lab · ≈52 minSeparate the spectrum routes to orbit, size what one beam honestly carries, and read the release train for which capability is actually specified.
Module 5 — What is flying, what is specified, and what to track
6 lessons · 2 lab · ≈52 minSeparate the spectrum routes to orbit, size what one beam honestly carries, and read the release train for which capability is actually specified.
- 18:10MSS allocations and leased terrestrial spectrum: two routes to orbitRequires subscription
- 28:44UE pre-compensation and payload compensation: who does the workRequires subscription
- 38:57Per-beam capacity: what one footprint can actually carryRequires subscription
- 48:39NB-IoT and eMTC over NTN: the standards-native business already shippingRequires subscription
- 59:06PLMN selection, roaming and emergency routing: what an operator actually signsRequires subscription
- 68:46Rel-17 to Rel-20: reading the NTN release trainRequires subscription
- ~6 minOne Beam, Everybody Under ItInteractive lab
Divide one beam's illustrative 8 Mbit/s across a declared crowd of handsets, then switch to sensors on the uplink slice. Find where a share falls to a tenth, where sensors ask for what one handset takes — and where airtime would run out, and why it doesn't.
- ~6 minWhich Track Owns It?Checkpoint
Ten cards from this course, three parallel tracks, and one card that belongs to an earlier release than almost everyone assumes.
New to the terminology? Look up any acronym in the telecom glossary.
Take the certification exam
Earns a certificate35 questions · 60 min · 65% to pass. Score 65%+ to earn your TELCOMA Certified NTN Specialist — a QR-verifiable certificate.
Not ready yet? Take a free 20-question mock exam first.
Study materials
Download the NTN & Direct-to-Device: 5G from Orbit question bank and slide deck — every signal check in the course, with answers, plus every figure.
- Question BankPDF37 KB
- Slide DeckPPTX15 MB
Unlock every lesson in NTN & Direct-to-Device: 5G from Orbit
Stream all 27 lessons, follow the 5-module path, and earn the TELCOMA NTN Specialist certificate.
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