Satcom Performances and Constraints

Description

This lecture covers the performances and constraints of satellite communications (Satcom), focusing on bandwidth, quality of service, infrastructure, and satellite orbits. It discusses the technology-driven aspects, such as data allowance and availability, as well as the impact of satellite orbits on performance. The lecture also compares the performance of High Throughput Satellite (HTS) networks in Low Earth Orbit (LEO) with Fixed Satellite Service (FSS) from Geostationary Orbit (GEO), using examples like Starlink, HughesNet, and Viasat. Furthermore, it explores the radio spectrum utilization, advantages and disadvantages of different frequency bands, and the inherent performance drivers of Satcom technology. The presentation concludes with an overview of satellite orbits, including Geostationary Earth Orbit (GEO), Medium Earth Orbit (MEO), and Low Earth Orbit (LEO), highlighting their visibility, altitude, latency, and ground station requirements.

In MOOCs (2)

Official source

https://mediaspace.epfl.ch/media/0_5uzedapb

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Related lectures (3)

Related concepts (97)

Geostationary orbit

A geostationary orbit, also referred to as a geosynchronous equatorial orbit (GEO), is a circular geosynchronous orbit in altitude above Earth's equator, in radius from Earth's center, and following the direction of Earth's rotation. An object in such an orbit has an orbital period equal to Earth's rotational period, one sidereal day, and so to ground observers it appears motionless, in a fixed position in the sky. The concept of a geostationary orbit was popularised by the science fiction writer Arthur C.

Geosynchronous orbit

A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day.

Low Earth orbit

A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never more than about one-third of the radius of Earth. The term LEO region is also used for the area of space below an altitude of (about one-third of Earth's radius). Objects in orbits that pass through this zone, even if they have an apogee further out or are sub-orbital, are carefully tracked since they present a collision risk to the many LEO satellites.

Communications satellite

A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Many communications satellites are in geostationary orbit above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite.

Geostationary transfer orbit

A geostationary transfer orbit (GTO) or geosynchronous transfer orbit is a type of geocentric orbit. Satellites that are destined for geosynchronous (GSO) or geostationary orbit (GEO) are (almost) always put into a GTO as an intermediate step for reaching their final orbit. A GTO is highly elliptic. Its perigee (closest point to Earth) is typically as high as low Earth orbit (LEO), while its apogee (furthest point from Earth) is as high as geostationary (or equally, a geosynchronous) orbit.