Abstract: Methods including computer program products for receiving a request from a first device, the request incorporating a message. One or more users from a first set of one or more users are selected where each of the selected one or more users is associated with a second device that is in a proximity to a current location of the first device. The message and the current location of the first device are sent to each of the second devices associated with the selected one or more users.

Abstract: Locating satellites (e.g., GPS) are culled into a preferred group having a longest dwell time based on a time passing through an ellipsoid arc path through a cone of space, and communicated to mobile devices within a particular region (e.g., serviced by a particular base station). The locating satellites may be culled into a prioritized list. Each satellite is assigned an order of precedence based on a remaining dwell time within a primary inverted cone. Thus, a number ‘N’ of satellite's ephemeris data may be used, along with a preferred ‘order of precedence’ for secondary satellites to be used as backups as necessary.