GEO-Mobile Radio Interface
GEO-Mobile Radio Interface (GMR) is a standard for satellite telephony from the European Telecommunications Standards Institute (ETSI).
Two parallel standards are defined, GMR-1 (ETSI TS 101 376) and GMR-2 (ETSI TS 101 377).
GMR-1
GMR-1 is used in the services of the operators Thuraya Telecommunications, SkyTerra Communications, TerreStar Networks and ICO Global Communications. It leans heavily on GSM . The transmission protocol only differs on the lowest three OSI layers , for GmPRS only on the lowest two. Further, specialized features are device-to-device calls and what is known as “high penetration alerting” (HPA, for example “ call signaling with high penetration”). The end-to-end calls are transferred directly from the satellite to the remote station without having to be routed over the network and then again over the satellite. The high penetration alerting allows notification of an incoming call even inside closed rooms, whereas the calls can only be conducted outdoors. AMBE is used as the audio codec . A5-GMR-1 , a proprietary algorithm probably derived from A5 / 2, and A5-GMR-2, both of which were broken in 2012, are used for encryption . The system integrates closely with GPS . GMR-1 also includes a packet-oriented service called GmPRS (analogous to GPRS ).
The OsmocomGMR project is developing a free protocol stack for GMR-1.
swell
- Sylvain Munaut: Introducing Osmo-GMR . Building a sniffer for the GMR satphones. In: 28c3 . Berlin December 29, 2011 (English, ccc.de ).
- ^ Benedikt Driessen: An analysis of the GMR-1 and GMR-2 standards. February 8, 2012, accessed February 8, 2012 .
- ↑ OsmocomGMR project website