| 摘要 |
<p>A communication system (100) includes a plurality of organizational layers (102, 104, 106, 108, 110), a plurality of portable communication units (20, 22, 24), and a plurality of base stations (112). Each layer comprises a plurality of nodes. The plurality of nodes includes a plurality of base stations (112) in the first layer, and a plurality of communication services nodes organized into higher layers (102, 104, 106, 108, 110). Each communication services node includes a database possibly containing information on the locations of one or more portable communication units (24). The databases constitute a distributed database containing information on the locations of some of the portable communication units (24) within the system (100), and a tracing strategy is realized by the transmission of control messages (306) informing the system of a moving portable communication unit's (24) location. The system tries to set up a connection (120) to the home address of the called portable communication unit. If there is information on the called unit (24), its location is indicated by the address chain (138) in the distributed database.</p> |
