Patent ID: 7586913

Claim:
A mobile IP packet communication system comprising: a plurality of mobile terminals; a plurality of radio base stations each configured to communicate with said mobile terminals; a plurality of base station control apparatuses each configured to manage the plurality of said radio base stations and to control radio channels; a plurality of subscriber packet exchange apparatuses each configured to manage a routing area including a plurality of said radio base stations and a single base station control apparatus and to control a transfer of packets to one of said plurality of mobile terminals; a gateway and packet data exchange apparatus connected to each of said plurality of subscriber packet exchange apparatuses and a data packet network disposed outside said mobile IP packet communication system and configured to serve as a gateway between each of said plurality of subscriber packet exchange apparatuses and said data packet network disposed outside said mobile IP packet communication system; a home location register configured to manage information regarding routing areas in which said plurality of mobile terminals are currently located, respectively; and a plurality of visitor location registers each configured to manage information regarding zones within a corresponding routing area in which said plurality of mobile terminals may be currently located, wherein when transferring a data packet destined for a first one of said plurality of subscriber packet exchange apparatuses that manages the routing area in which one of said plurality of mobile terminals, that is the destination, is currently located, said mobile IP packet communication system is configured to transmit the data packet between a second one of said plurality of subscriber packet exchange apparatuses that manages a routing area in which one of said plurality of mobile terminals, that is a sending source, is currently located and said gateway and packet data exchange apparatus, between said second one of said plurality of subscriber packet exchange apparatuses and each of said plurality of subscriber packet exchange apparatuses after copying the data packet a number of times, equal to the number of subscriber packet exchange apparatuses linked to said second subscriber packet exchange apparatus and encapsulating said copied data packets with a multicast address, without acquiring location information on a location of said destination one of said plurality of mobile terminals, and between said second one of said plurality of subscriber packet exchange apparatuses and said first one of said plurality of subscriber packet exchange apparatuses after encapsulating the data packet by adding unicast address information corresponding to said first one of said plurality of subscriber packet exchange apparatuses that is the destination of the data packet when said first one of said plurality of subscriber packet exchange apparatuses confirms that said one of said plurality of mobile terminals, that is the destination, is currently located therein.