Mobile satellite system/terrestrial wireless system interworking techniques

Abstract

Methods for switching a mobile between operation in an mobile satellite system mode and a terrestrial wireless mode. When operating in the terrestrial wireless mode, the mobile terminal will initiate an attempt to switch into the MSS mode when it nears the boundary of the coverage area for a terrestrial wireless system to which it is registered. Conversely, a mobile terminal operating in the MSS mode will regularly attempt to switch into the terrestrial wireless mode. For both, a switch between modes is contingent on the mobile terminal identifying a suitable system for registration therewith upon completing the switch between modes. The criteria for identifying a suitable system for selection purposes include the following: (1) the selected system is available, i.e., the mobile terminal is physically located within a coverage area for the selected system; (2) the mobile terminal is compatible with the selected system; and (3) the selected system is willing to accept the mobile terminal. If multiple systems meet these criteria, the mobile terminal will utilize a stored list of preferred systems to select therefrom. When switching into the terrestrial wireless mode, the MSS system provides the mobile terminal with switch-over information for the underlying terrestrial wireless systems and, when switching into the MSS mode, the terrestrial wireless system provides the mobile terminal with switch-over information for the overlying MSS systems.