User key validation to prevent fraud during system handoffs

Abstract

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.