Iridium, Thuraya, Inmarsat – Satellitennetzwerk

Thuraya — Satellite network

The Thuraya network has the area code: +88216.

The Thuraya satellite network is operated with 2 satel­lites on a geosyn­chronous orbit about 36,000 km above the equator, whose coverage areas include 140 countries and are divided into 200 spot beams (focused radio areas). Assignment to the correct spot beam is based on the phone’s GPS position. For geosyn­chronous satel­lites, the apparent location of the satel­lites in the sky is not fixed as it is for geosta­tionary satel­lites, but varies slightly throughout the day. Therefore, the transmit power levels fluctuate at the edges of the coverage areas. For calls within the Thuraya network, the connection goes directly over the satellite and does not “touch” the ground on its way. For calls from or to terres­trial fixed and mobile networks, the calls are routed to earth via a gateway (ground station) in Sharjah (UAE).

On a high trans­mission power “Sat-Alert” channel, the phone (even with the antenna folded in and in an unfavorable location) is first alerted to an incoming call (HPA High Penetration Alerting), the user then moves to a location with a clear view to the satellite’s position (in Europe mostly to the southeast). Now the phone logs onto the spot beam assigned according to the GPS position. The coverage zones can be shifted by changing the spot beam config­u­ration. For example, after the Thuraya 2 satellite (Indonesia), which covers parts of Asia, went into operation, the coverage zone in Africa was improved by changing the spot beams of Thuraya 1 (off the coast of Somalia).

Ausleuchtung des Thuraya-Netzwerkes in 140 Ländern.
Ausleuchtung des Thuraya-Netzwerkes in 140 Ländern

The built-in GPS receiver is on the one hand necessary for estab­lishing a connection to the satellite, but can also be used for own location deter­mi­na­tions, e.g. for emergency calls and tracking.

Since Thuraya uses a protocol derived from GSM (mobile telephony), this system is very similar to normal GSM usage, only with a bit more delay. The GmPRS (Geo Mobile Packet Radio Service) data channel provides higher rates than Iridium phones, namely 60 kbps download and 15 kbps upload. The GmPRS data service is packet-based and is therefore charged according to data volume.

About the history of Thuraya

Thuraya was founded in 1997 with headquarters in Sharjah in the United Arab Emirates. Its share­holders include Arab telecom­mu­ni­ca­tions companies (such as Etisalat and Arabsat) and investment firms (such as the Abu Dhabi Investment Company and Dubai Invest­ments), as well as the T‑Systems company DETECON.

The satel­lites were manufac­tured by Boeing (Hughes) and, with a launch weight of more than 5.1 tons, are among the heaviest commu­ni­ca­tions satel­lites in the world. They were launched using Zenit-3SL (Sea Launch) rockets. The antennas have a diameter of 12 meters. Due to the size of the antenna and a strong trans­mitting power as well as a high receiving sensi­tivity, the cell phones can be relatively small although they are far away from the satellite.