In-flight connectivity over 5G/6G NTN

LEO constellation · Ka band · Earth-moving beams

We compare in-flight connectivity over a Bangalore to Delhi flight for two constellation sizes, 50 and 100 satellites, measured by SINR, throughput, and latency. We model the constellation and its orbits, the antennas and the RF channel, and the flight path. NetSim then simulates the entire flight and reports each KPI.

2 h 12 min flight 1739.81 km route Ka band n510 200 MHz downlink 50 against 100 satellites
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NetSim · the aircraft at Bangalore, t = 0 s
NetSim scenario view over India showing the aircraft at Bangalore, the flight path to Delhi, the satellite gateway, and two visible satellites

What you can model

Simulate end to end: satellite orbits, antennas and RF, the flight path, and protocol operation, then analyse throughput and latency.

Constellation size

Change the constellation size. Hold the route, the radio, and the traffic fixed, then read the effect on delivered service.

Serving-satellite association

Follow the satellite that serves the aircraft at each instant. See how long it holds, and when service passes to the next one.

Link budget in motion

Track elevation angle, slant range, beam gain, and path loss as the aircraft and the satellites move.

What the cabin receives

Measure application throughput and packet delay at the aircraft, where the passenger session runs.

The scenario

Bangalore to Delhi in 2 h 12 min at about 800 km/h. Ka-band satellites at 550 km altitude with 200 MHz bandwidth and EIRP density 59 dBW/MHz. A saturation traffic load measures the maximum throughput the link can deliver.

Flight

Bangalore to Delhi, 2 h 12 min

  • File Based Mobility moves the aircraft along time-stamped waypoints
  • 1739.81 km straight-line route over a 7920 s simulation
  • NetSim derives the speed from the waypoint spacing: about 790.82 km/h, or 427.00 knots
Radio

Ka band n510, 200 MHz

  • 200 MHz downlink and 200 MHz uplink
  • Gaussian antenna model, with one Earth-moving beam per satellite
  • Free-space path loss with a 10 degree elevation mask
  • Aircraft antenna gain 25 dB, maximum antenna gain 30 dB, EIRP density 59 dBW/MHz
Traffic

Downlink full buffer over UDP

  • Remote server to aircraft, with 4000 packets in flight
  • While a satellite serves the aircraft, the downlink runs as fast as the link allows
  • The two runs differ in one parameter only: 50 satellites against 100

The end-to-end path

Traffic reaches the cabin through the 5G core and the satellite gateway. Each satellite carries one Earth-moving beam, so the footprint travels with the satellite. The aircraft receives service only inside that footprint.

End-to-end downlink path: remote server, 5G core, satellite gateway, feeder link up to the serving satellite, then the Ka-band service link down to the aircraft inside the Earth-moving beam.

Scroll sideways to see the whole diagram.

The downlink path runs in traffic order. Full Buffer traffic starts at the remote server (1) and crosses the 5G core to the satellite gateway (2). The traffic then climbs the feeder link to the serving satellite (3) and reaches the aircraft over the Ka-band service link (4).

Why the serving satellite changes

Two conditions must hold together. The satellite must sit above the 10 degree elevation mask, and the aircraft must lie inside its beam. Elevation angle and slant range change all the time, and both drive the received SINR.

Link geometry seen from the aircraft. The serving satellite has the highest elevation and the shortest slant range; the setting satellite loses SINR as its slant range grows; the rising satellite sits in the shaded zone below the 10 degree elevation mask, where it cannot serve yet.

Scroll sideways to see the whole diagram.

The serving satellite offers the highest elevation and the shortest slant range. The setting satellite loses SINR as its slant range grows. The rising satellite still sits below the mask, so it cannot serve yet. When no satellite meets both conditions, service stops, and the timeline below shows a gap.

Two NetSim snapshots during the flight. Early on, the aircraft is served by PL-1-SAT-1 at 28.5 Mbps; ninety minutes later it is served by PL-1-SAT-3 at 49.9 Mbps while another satellite is visible but not serving.

Two instants in the 100-satellite run. The blue link and the throughput badge mark the serving satellite. Early in the flight PL-1-SAT-1 serves the aircraft at 28.5 Mbps. Ninety minutes later PL-1-SAT-3 serves it at 49.9 Mbps, while another satellite stays visible but does not serve.

50 satellites against 100

Same route, same radio, same traffic. Only the constellation size changes, so the difference shows what those extra satellites are worth.

50 satellites 100 satellites Change, 50 → 100
Application throughput 31.78Mbps 48.21Mbps +51.7%
Mean serving throughput 59.49Mbps 68.53Mbps +15.2%
Mean downlink SINR −5.64dB −4.97dB +0.67 dB
Mean packet delay 24.43s 13.93s −43.0%
Service availability 61.4% 69.7% +8.3 pp

The handover timeline

Each bar is service with a serving satellite. Lane represents the orbital plane, and its shade gives the SINR. The blank stretches are gaps, where no satellite serves the aircraft.

Peak SINR −7 dB to +31 dB No serving satellite Bar label: satellite index within the orbital plane
50 satellites PL-1 PL-7 PL-8 PL-1-SAT-1 · 00:00 to 00:07 · peak SINR -4.33 dB 1 PL-1-SAT-5 · 00:20 to 00:28 · peak SINR -0.53 dB 5 PL-7-SAT-1 · 00:37 to 00:43 · peak SINR -3.57 dB 1 PL-1-SAT-4 · 00:44 to 00:48 · peak SINR 3.14 dB 4 PL-7-SAT-5 · 00:56 to 01:03 · peak SINR -1.48 dB 5 PL-1-SAT-3 · 01:04 to 01:09 · peak SINR 15.31 dB 3 PL-7-SAT-4 · 01:15 to 01:23 · peak SINR 30.18 dB 4 PL-1-SAT-2 · 01:24 to 01:29 · peak SINR 22.28 dB 2 PL-7-SAT-3 · 01:34 to 01:42 · peak SINR -0.32 dB 3 PL-1-SAT-1 · 01:44 to 01:50 · peak SINR 4.00 dB 1 PL-8-SAT-2 · 01:51 to 01:53 · peak SINR -5.87 dB 2 PL-7-SAT-2 · 01:54 to 02:01 · peak SINR -6.23 dB 2 PL-1-SAT-5 · 02:02 to 02:10 · peak SINR 0.34 dB 5 61% of the flight served 13 serving intervals 6.2 min mean dwell 100 satellites PL-1 PL-7 PL-1-SAT-1 · 00:00 to 00:07 · peak SINR -3.65 dB 1 PL-1-SAT-10 · 00:13 to 00:17 · peak SINR -2.16 dB 10 PL-1-SAT-9 · 00:20 to 00:28 · peak SINR -2.79 dB 9 PL-7-SAT-2 · 00:28 to 00:33 · peak SINR -5.83 dB 2 PL-1-SAT-8 · 00:34 to 00:38 · peak SINR -4.03 dB 8 PL-7-SAT-1 · 00:38 to 00:43 · peak SINR -3.52 dB 1 PL-1-SAT-7 · 00:43 to 00:48 · peak SINR -0.14 dB 7 PL-7-SAT-10 · 00:49 to 00:53 · peak SINR -2.52 dB 10 PL-1-SAT-6 · 00:53 to 00:58 · peak SINR 4.68 dB 6 PL-7-SAT-9 · 01:00 to 01:03 · peak SINR -1.22 dB 9 PL-1-SAT-5 · 01:03 to 01:08 · peak SINR 3.82 dB 5 PL-7-SAT-8 · 01:08 to 01:13 · peak SINR 3.89 dB 8 PL-1-SAT-4 · 01:14 to 01:18 · peak SINR 18.80 dB 4 PL-7-SAT-7 · 01:18 to 01:23 · peak SINR 30.41 dB 7 PL-1-SAT-3 · 01:24 to 01:29 · peak SINR 23.49 dB 3 PL-1-SAT-2 · 01:34 to 01:38 · peak SINR 5.06 dB 2 PL-7-SAT-5 · 01:38 to 01:42 · peak SINR 0.95 dB 5 PL-1-SAT-10 · 01:56 to 02:00 · peak SINR 0.34 dB 10 PL-1-SAT-9 · 02:04 to 02:10 · peak SINR 1.73 dB 9 70% of the flight served 19 serving intervals 4.8 min mean dwell 0:00 0:15 0:30 0:45 1:00 1:15 1:30 1:45 2:00 Elapsed flight time (h:mm), Bangalore to Delhi

Scroll sideways to follow the whole flight.

Orbital planes take turns

The aircraft alternates between orbital planes PL-1 and PL-7 for most of the route. The handover sequence follows whichever plane has a satellite above the mask.

Dwell time falls as density rises

Doubling the constellation cuts the mean dwell from 6.2 min to 4.8 min. Each satellite holds the aircraft for a shorter part of its pass, and handovers rise from 13 to 19 in step.

Over the flight

We compare the two runs over a common time axis. The shaded bands are the gaps, where no satellite serves the aircraft.

Downlink throughput against time for both runs, mostly below 50 Mbps with short peaks above 400 Mbps near beam centre

Both runs stay below 50 Mbps for most of the flight. Each run peaks above 400 Mbps when the aircraft passes close to beam centre at high elevation. The 100-satellite run holds a higher floor and shows fewer, narrower gaps.

Downlink SINR against time for both runs, mostly below 0 dB with a peak near 30 dB around 1:15 to 1:30

Downlink SINR stays below 0 dB for most of the flight in both runs. The 100-satellite run holds a higher mean, and it steps more often because its serving intervals are shorter.

Application packet delay against time for both runs, with large spikes immediately after each gap in service

Every large delay spike falls immediately after a gap. The queue drains once the link returns, so the spikes show backlog rather than propagation delay.

Share of connected flight time above throughput and SINR thresholds, comparing the two runs

Each bar represents the share of connected time spent above that level. The 100-satellite run spends more of the flight in good radio conditions. It stays above 25 Mbps for 85 per cent of connected time, against 79, and above −5 dB for 41 per cent, against 34. That extra time at the better levels lifts its mean SINR from −5.64 dB to −4.97 dB.

What the result means

Doubling the constellation buys availability: more minutes of the flight with a serving satellite, and shorter gaps between them.

Availability

The gain is coverage

Both runs reach similar peaks: SINR near 30 dB, and throughput above 400 Mbps close to beam centre. The gain shows up in service availability, which rises from 61 to 70 per cent of the flight.

Delay

The delay spikes follow the gaps

Under full-buffer downlink the baseline delay runs to tens of seconds. Every large spike follows a gap, as queued traffic drains once the link returns. Shorter gaps halve the mean, from 24.43 s to 13.93 s.

Trade-off

More satellites, more handovers

Nineteen serving intervals instead of 13 means more handovers to carry. The sparser constellation holds one satellite for 6.2 min. That longer dwell rides further into the high-elevation part of each pass, so it keeps more time at the highest thresholds.

Related product

Satellite link budget and coverage planning

Where NetSim simulates the network, NetSim Astra plans the constellation over real geography. Use the two together to move from coverage design to end-to-end performance.

  • Constellation and orbital-plane design
  • Link budgets for satellites
  • Coverage and footprint studies over real geography
Explore NetSim Astra

Read the full write-up, explore the NTN library behind this study, or ask us to run your own route.

The full case study → Configuration, both interval timelines, and every summary table (PDF). 5G/6G NTN library → Orbits, spot beams, link budgets, and what the library models. 38.821 reference scenario → The 3GPP baseline: 19 beams, 190 UEs, transparent payload. NetSim NTN Q&A → Scheduling under satellite delay, and what is not modelled. Satellite communication → Satellite modelling across the rest of NetSim. Run it on your route → Request an evaluation and we will set up your flight path and constellation.