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Communication protocol for mobile earth terminal communication device used in mobile satellite communication system

  • US 5,850,602 A
  • Filed: 05/28/1996
  • Issued: 12/15/1998
  • Est. Priority Date: 08/15/1995
  • Status: Expired due to Fees
First Claim
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1. In a mobile satellite system including a satellite communication switching office (SCSO) having a satellite antenna for receiving/transmitting a satellite message via a satellite from/to a mobile communication system (MCS), a central controller receiving/transmitting the satellite message from/to the satellite communication switching office issued from the MCS via the satellite to another party, a method of performing a call setup procedure in the mobile satellite system from a call initiated by the MCS to a destination served by a public switched telephone network (PSTN), said method comprising the steps of:

  • (a) initiating the call by the MCS;

    (b) the MCS formatting and transmitting an access request message via a random access channel, the access request message including call type and destination number;

    (c) receiving by the central controller the access request message, and transmitting frequency assignments to the MCS via a time division multiplex (TDM) channel and to the SCSO via an interstation signaling channel, the frequency assignment including the call type, and the destination phone number, and an access security check field used to verify the MCS'"'"'s identity;

    (d) receiving by the MCS the frequency assignment, and transmitting a scrambling vector message to the SCSO via the single channel per carrier (SCPC) communication channel;

    (e) verifying by the SCSO the identity of the MCS responsive to the scrambling vector;

    (f) upon successful verification in said verifying step (e), switching by the SCSO and the MCS from call setup mode to voice mode;

    (g) transmitting by the SCSO voice frames to the MCS to disable voice activation in the MCS for at least 3 super frames after which voice activation is re-enabled in the MCS, and transmitting a destination number to the PSTN; and

    (h) establishing voice communication between the PSTN and the MCS.

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