Satellite communication is the use of artificial Earth-orbiting satellites as relay stations to transmit signals — including voice, data, video, and telemetry — between ground terminals separated by large distances or challenging terrain. Signals are uplinked from a ground station to a satellite transponder, which amplifies and retransmits them on a different frequency to one or more receiving terminals. Different orbital regimes (GEO, MEO, LEO) offer distinct trade-offs between coverage footprint, latency, and capacity.
Overview
- Satellite communication emerged in the 1960s and has grown into a critical global infrastructure supporting broadcasting, telephony, internet backhaul, navigation, and Earth observation. GEO satellites provide continental coverage from a fixed position but impose roughly 480–600 ms round-trip latency; LEO constellations (e.g., Starlink, OneWeb) offer low-latency broadband but require large numbers of satellites and complex handover systems.
- Modern systems increasingly use high-throughput satellites (HTS) with frequency reuse across spot beams, dramatically increasing capacity per satellite. Integration with terrestrial networks via non-terrestrial network (NTN) standards is extending satellite connectivity to smartphones and IoT devices.
Key aspects
- Orbital regime selection — GEO favours broadcast and backhaul; LEO/MEO favour broadband and navigation.
- Link budget design — antenna gain, transmit power, atmospheric losses, and noise figure determine achievable data rates.
- Spectrum coordination — adjacent satellite system interference requires careful frequency planning and ITU filing procedures.
- Latency characteristics — GEO latency precludes real-time interactive applications; LEO latency is comparable to long-distance fibre.
Applications
- Maritime and aviation in-flight connectivity beyond terrestrial mobile coverage.
- Disaster-recovery communications when terrestrial networks are destroyed.
- Direct broadcast satellite (DBS) television distribution.
- Backhaul for remote cellular base stations and offshore platforms.
Mechanisms
- Frequency division — C-band, Ku-band, Ka-band, and V-band offer different rain-fade characteristics and regulatory environments.
- Modulation and coding — DVB-S2X and adaptive coding modulation (ACM) optimise link efficiency under varying conditions.
- On-board processing — digital regenerative payloads demodulate and re-encode signals, reducing noise accumulation.