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Fixed Satellite Service (FS)

Overview of Fixed Satellite Service (FS)​

The Fixed Satellite Service (FS) is a crucial component of global communications, providing reliable and high-capacity links between fixed Earth stations via satellite. FS is primarily used to establish fixed communication channels, which are essential for broadcasting, internet services, and data transfer, especially in regions where terrestrial infrastructure is limited or non-existent. FS typically utilizes geostationary satellites, which remain in a fixed position relative to the Earth’s surface, ensuring continuous coverage for communication links.

Key Features of Fixed Satellite Service​

  • Fixed Communication Links: Unlike mobile satellite services, FS is designed for permanent, reliable communication between Earth stations, usually supporting one-to-one or point-to-multipoint communication.
  • Geostationary Satellites: FS relies heavily on geostationary satellites that orbit at approximately 36,000 km above the equator, maintaining a fixed position relative to the Earth.
  • High-Capacity Links: FS supports high-capacity communications, including voice, video, and broadband data services. This capacity is essential for television broadcasting, internet access, and corporate communications.

Typical Applications of FS​

  • Television Broadcasting: Satellite TV services that deliver content globally, especially to remote or underserved areas.
  • Internet Access: Providing broadband services to rural or remote areas through VSAT (Very Small Aperture Terminal) technology.
  • Corporate Networks: Enabling secure communication links between headquarters and remote offices, particularly in regions with limited terrestrial infrastructure.
  • Emergency Communications: Supporting critical communications during disasters or emergencies when terrestrial networks are unavailable.
  • Government and Military: Facilitating secure and stable communication for government and military operations, especially in remote or hostile environments.

Core Components of FS​

The basic components of Fixed Satellite Service include the Earth Station, the Satellite, and the Ground Segment. Each plays a crucial role in the satellite communication process:

1. Earth Station​

The Earth Station is the ground-based facility responsible for transmitting and receiving signals to and from the satellite. It typically consists of the following:

  • Antenna System: A large, high-gain parabolic dish that focuses signals precisely on the satellite, ensuring a stable and strong communication link.
  • Transmitter and Receiver Equipment: Includes high-power amplifiers (HPAs) for transmission and low-noise amplifiers (LNAs) for reception to ensure signal integrity over long distances.
  • Control Systems: Equipment that monitors the Earth station's performance, adjusts antenna alignment, and ensures compliance with communication standards.

2. Satellite​

The satellite acts as the relay point for communications, receiving signals from Earth stations and transmitting them to their destination. Most FS systems use geostationary satellites, but in some cases, non-geostationary satellites are also employed. These satellites typically feature:

  • Transponders: Devices that receive, amplify, and retransmit signals from Earth stations.
  • Orbiting Systems: Satellites are placed in geostationary orbit to provide continuous coverage over the same geographic area.

3. Ground Segment​

The ground segment consists of additional infrastructure, including terrestrial communication networks, data centers, and satellite control stations that ensure the satellite system's operational integrity.

Frequency Bands for Fixed Satellite Service​

Fixed Satellite Service operates across several frequency bands, each tailored to specific types of communication needs. These include:

  • C-band: Ranges from 3.7 to 4.2 GHz for downlink and 5.925 to 6.425 GHz for uplink. This band is resistant to rain fade, making it ideal for consistent, all-weather communication, such as for television broadcasts.
  • Ku-band: Ranges from 10.7 to 12.75 GHz for downlink and 13.75 to 14.5 GHz for uplink. Offers higher bandwidth and is commonly used for satellite TV and broadband internet services, though more susceptible to rain fade.
  • Ka-band: Ranges from 17.7 to 21.2 GHz for downlink and 27.5 to 31 GHz for uplink. Supports high-capacity broadband services but is the most sensitive to atmospheric conditions like rain and humidity.
  • Q-band: Ranges from 33 to 36 GHz for downlink and 50.4 to 51.4 GHz for uplink. Typically used for advanced communications and high-speed data transfer, though it is more affected by atmospheric interference.

To ensure efficient communication, the design of satellite links in FS must account for several factors, including:

  • Link Budget: Ensuring adequate power levels for both uplink and downlink communications, accounting for factors like antenna size, transmission power, free-space path loss, and atmospheric attenuation.
  • Earth Station Antenna Design: The size and gain of Earth station antennas must be appropriately designed to provide the necessary link budget while minimizing interference.
  • Satellite Coverage: Satellites must be positioned to ensure optimal coverage of the desired geographic region, with minimal signal degradation from obstacles or weather conditions.
  • Interference Management: Spectrum management is crucial to prevent interference from other services, both within the satellite communication system and with terrestrial systems. This includes coordination of frequency use and power control.

Regulations and Compliance​

FS operates within a regulatory framework set by the International Telecommunication Union (ITU), which ensures spectrum allocation and operational standards to minimize interference and maximize the efficiency of satellite systems. Key ITU recommendations include:

  • ITU-R S.524: Guidelines for the technical characteristics of FS Earth stations and their link budgets.
  • ITU-R S.686: Spectrum management and coordination of satellite networks to avoid interference between services.
  • ITU-R F.1487: Provides guidelines for the implementation of FS services in terms of frequency planning and coordination of frequency use.

Summary​

Fixed Satellite Service (FS) plays a pivotal role in global communications by providing reliable, high-capacity communication links that support a variety of essential services, including television broadcasting, internet access, and emergency communications. Through the use of geostationary satellites, FS systems deliver consistent and stable communication, especially in areas where terrestrial infrastructure is insufficient.

Key Takeaways​

  • Geostationary Satellites: Ensure continuous, fixed communication with Earth stations.
  • Core Applications: TV broadcasting, broadband internet, corporate data, emergency response, and military communications.
  • Frequency Bands: C-band, Ku-band, Ka-band, and Q-band serve different communication needs with varying levels of susceptibility to weather interference.
  • Link Design: Proper satellite link budgets, antenna design, and interference management are critical for ensuring high-quality service.

For further reading and technical specifications, consult the ITU guidelines and standards: