Abstract: A system and method provides signaling privacy for communications between nodes of a communications network (30). Multiple logical links exist between distinct network nodes (38-40, 42, 50-53) of the communication network (30). Signaling privacy is achieved by a subscriber unit (80) providing encryption/decryption of signaling data messages at the messaging level. The subscriber unit (80) employs a signaling encryptor/decryptor (86) along the signaling path, which enables the signaling data messages to be separately encrypted from data on the traffic channel. The encrypted signaling data can then be sent along a different logical link from the traffic, while maintaining cipher key synchronization between the signaling encryptor/decryptor (86) and a network encryptor/decryptor (78) at a remote end of the logical link which transports the encrypted signaling data.

Abstract: In a global satellite communication system (10) that provides antenna beams that move with respect to Earth's surface, gateways (22) send ring alerts directed to subscriber units (26) based on a list of antenna beams. The list of antenna beams is determined by a dot product between a subscriber unit's basis vector and antenna beam vectors. Ring alerts are transmitted in antenna beams when the dot product exceeds a predetermined threshold. Subscriber units listen for ring alerts in the same antenna beams of the list by calculating the list the same way the gateway calculates the list.

Abstract: In a satellite communication system (10, 30) with at least one ground based transmitter (12, 32), at least one ground based receiver (16, 36) and at least one communication satellite (14, 34), an earth-based receiver (16, 36) self-determines its Doppler correction factors using software algorithms which minimize the amount of hardware required and minimize the time required to acquire the signal.

Abstract: A system (28) provides communication services to mobile units (24). Mobile units (24) perform a unit-based location process (46, 48) to determine their locations. The system (28) performs a system-based location process (64, 66) to independently determine mobile unit locations. The system-based process may determine location less precisely than the unit-based process. A location selection process (104) evaluates the unit-determined location in view of a system-determined location error region to decide whether the unit-determined location is reliable. If the unit-determined location is reliable, it is used (120) to qualify communication services to be provided to the mobile unit (24). If the unit-determined location is unreliable, the system-based process is repeated (116) to improve the system-determined location precision, and the resulting system-determined location is used (118) to qualify communication services to be provided to the mobile unit (24).

Abstract: A global communication system must comply with service restrictions when operating across political and other restrictive boundaries. The location of a subscriber unit must be correlated to a service area region for identifying and extending appropriate restrictions and services. The Earth is partitioned into equally spaced areas (125, 130) with entries stored in database records. Service area boundary data (205) overlays the equally spaced areas (125, 130) to assign each equally spaced area to a location area enabling efficient use of the communication system. Equally spaced areas (125, 130) are iteratively subdivided to form a hierarchical database (350) when service area boundary data (205) bisects an equally spaced area (125, 130).