Satellite Internet

How LEO Satellite Internet Works

Unlike traditional GEO satellites at 35,786 km (240 ms round-trip latency), LEO constellations orbit at 340–1,200 km, achieving latencies of20–50 ms — comparable to terrestrial broadband. The tradeoff: LEO satellites move across the sky in minutes, requiring thousands of satellites for continuous coverage and sophisticated handover between satellites.

A user terminal (dish) communicates with the satellite constellation viaKu-band (12–18 GHz) or Ka-band (26–40 GHz). Satellites relay data to ground stations (gateways) connected to the internet backbone via fiber. Inter-satellite links (ISLs) using laser crosslinks allow satellites to relay data between ground stations, reducing dependence on ground infrastructure.

Starlink

Starlink (SpaceX) is the largest LEO constellation, with over6,000 active satellites as of 2024. The initial constellation plan (FCC filing 2016) called for 12,000 satellites at 1,100–1,300 km altitude. A subsequent V2 expansion (FCC 2020) added 30,000 more, bringing the total authorized constellation to 42,000.

Starlink satellites are deployed in shells at different inclinations: 53° (primary US/ global coverage), 70°, and 97.6° (polar). Each satellite weighs approximately260 kg (V1.5) or 800 kg (V2), with a flat-panel design for efficient Falcon 9 / Starship launch stacking. V1.5 satellites includelaser inter-satellite links enabling polar route data relay without ground stations.

The Starlink user terminal (dish) uses a phased array antenna — a flat panel with hundreds of small antenna elements that electronically steer a beam to track satellites without mechanical movement. The terminal operates at 10.7–12.7 GHz (Ku-band receive) and 14.0–14.5 GHz (Ku-band transmit). The first-generation dish was 0.58 m diameter; the current standard dish is 0.48 m. Power consumption is approximately 50–75 W.

OneWeb

OneWeb (now Eutelsat OneWeb) operates a constellation of648 satellites at 1,200 km altitude in polar orbits (87.9° inclination). Launched between 2020 and 2023, the constellation provides global coverage including the Arctic and Antarctic. OneWeb uses Ku-band for user links and Ka-band for gateway links.

OneWeb targets enterprise, government, and maritime customers rather than consumers. A single OneWeb satellite provides ~5 Gbps of capacity, and the full constellation provides approximately 1.1 Tbps. Latency is approximately30–50 ms.

Amazon Kuiper

Project Kuiper (Amazon) plans to deploy 3,236 satellitesat 590–630 km altitude in three orbital shells (51.9°, 42°, and 33° inclination). The constellation is authorized by the FCC (2020) with a deployment deadline of 2026 for the first 1,618 satellites. Kuiper will use Ka-band (29.5–30.0 GHz uplink, 19.7–20.2 GHz downlink).

Amazon has developed custom phased array antennas and partnered with Blue Origin for launches. The Kuiper terminal is designed for low-cost mass production, with a target price under $400 for the consumer model. Amazon plans to integrate Kuiper with AWS services, offering satellite-backhauled edge computing.

Technical Challenges

• Doppler shift: LEO satellites at 7.5 km/s cause frequency offsets of ±45 kHz at Ku-band — terminals must track and compensate in real time
• Handover: Each satellite is visible for 5–15 minutes; terminals must seamlessly hand over between satellites without dropping connections
• Rain fade: Ku/Ka-band signals attenuate 5–20 dB/km in heavy rain — link budgets must include 10–15 dB rain margin
• Orbital debris: 42,000 Starlink satellites plus OneWeb and Kuiper create unprecedented traffic in LEO — collision avoidance is a growing concern
• Astronomical interference: Bright satellite trails interfere with optical astronomy — SpaceX has implemented visorSat and darkSat measures to reduce reflectivity

GEO vs. LEO Comparison