Abstract: Systems and methods are described for managing network connectivity for mobile users, particularly when a mobile user roams between two networks or between two subnets of a network. An announcer signal is broadcast by a host organization. The announcer signal includes a network identifier, an authorizer address and a verifier address. A mobile client monitors for the announcer signal and, when detected, provides an option to connect to the network via the authorizer. Once authorization is obtained, the mobile client communicates with the network through the verifier. The verifier received tagged data packets from a mobile client and only accepts the data packets if a valid tag (created with an authorization key) is included therewith. Multiple verifiers may be used to provide load balancing and fault tolerance (in the event a verifier fails).

Abstract: The position and orientation of a mobile unit is determined from ultrasonic waves received from beacons of known location. Orientation is determined from a phase difference of the sensed ultrasonic wave at plural receivers on the mobile unit. Signals from multiple beacons may be processed to solve for x, y and z position and for speed of sound. The receivers are spaced at greater than a half wavelength of the ultrasonic wave and signals from plural receivers are processed to remove multiple wavelength phase ambiguity. Two non-collinear sets of collinear receivers allow ambiguity resulting from symmetry of the receivers to be broken.

Abstract: Systems and methods are described for managing network connectivity for mobile users, particularly when a mobile user roams between two networks or between two subnets of a network. An announcer signal is broadcast by a host organization. The announcer signal includes a network identifier, an authorizer address and a verifier address. A mobile client monitors for the announcer signal and, when detected, provides an option to connect to the network via the authorizer. Once authorization is obtained, the mobile client communicates with the network through the verifier. The verifier received tagged data packets from a mobile client and only accepts the data packets if a valid tag (created with an authorization key) is included therewith. Multiple verifiers may be used to provide load balancing and fault tolerance (in the event a verifier fails).