Motorola Corporation

Thomas S Chu

Darryl Sale

Murali Ranganathan

Thomas Jake Hoppal

A method for efficiently and rapidly handing off a subscriber link from a first satellite ( ) to a second satellite ( ) in a satellite communications system ( ) uses a virtual connection ( ) between the first satellite ( ) and a subscriber ( ) through the second satellite ( ). The virtual connection ( ) is established soon after a handoff decision has been made. All signals subsequently received by the first satellite ( ) for direct transmission to the subscriber ( ) are then automatically transferred to the subscriber ( ) through the virtual connection ( ). The virtual connection ( ) is terminated after a &ldquo;call rerouted&rdquo; signal has been received from a remote gateway ( ).

Method for performing rapid handoffs in a wireless communication system using virtual connections

A user key validation during a handoff verifies the subscriber using the wireless communication system and prevents fraudulent use of the system. A wireless communication system ( ) has a number of satellites ( ) with which a subscriber unit ( ) establishes a communication link. However, as the quality of the transmitted signal between an active satellite ( ) and the subscriber unit ( ) degrades, a handoff of the communication link with the subscriber unit ( ) will occur if the subscriber ( ) meets the authentication requirements of the system ( ). The active satellite ( ) generates user keys and transmits the user keys to the active subscriber units ( ). A request of a handoff is made from the individual subscriber unit (ISU) ( ) to the losing SV ( ). The losing SV ( ) communicates with the gaining SV ( ) to establish a handoff. The losing SV ( ) sends the user key of the ISU ( ) to the gaining SV ( ). The gaining SV ( ) authenticates the ISU ( ) by comparing the ISU user key to a user key stored in the losing SV ( ). The gaining SV ( ) becomes the active satellite, and generates and transmits the user key to the ISU. Notification of the authentication is sent to an earth terminal controller (30). The earth terminal controller ( ) provides the losing SV ( ) with notification that the handoff is complete. The authentication a prevents further fraud if the subscriber fraudulently obtained access to the system during the original call set up.

User key validation to prevent fraud during system handoffs

An apparatus ( ) and method minimize voice delay by combining comfort noise with subframe insertions to fill gaps in speech and maintain a minimum delay for packets arriving late. When a packet is late, short durations of sound are repetitively inserted until the late packet arrives. When the late packet finally arrives, the durations of future speech pauses are modified so there is no voice degradation.

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Chandler, AZ, United States of America

Thomas S Chu