| 摘要 |
A communication system includes a plurality of organizational layers, a plurality of portable communication units, and a plurality of base stations. Each layer comprises a plurality of nodes. The plurality of nodes includes a plurality of base stations in the first layer, and a plurality of communication services nodes organized into higher layers. Each communication services node includes a database possibly containing information on the locations of one or more portable communication units. The databases constitute a distributed database containing the necessary and sufficient information on the locations of some of the portable communication units within the system, such that any active portable communication unit in its service area will be located using the most direct route. A tracing strategy is realized by the transmission of control messages informing the system of a moving portable communication unit's location. The system tries to set up a connection to the home address of the called portable communication unit, unless some information is found along the path to the home address of the called unit. In case there is information on the called unit its location is indicated by the address chain in the distributed database.
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