Packet transfer scheme and mobile communication system

A packet transfer scheme used in a mobile communication system comprising a database for storing an identification number of a mobile terminal and location information showing a zone in which said mobile terminal is currently located, and for rewriting said location information in accordance with a request from said mobile terminal, a plurality of first packet switches, each having a temporary storage means with a higher access speed than said database, a second packet switch capable of communicating with said mobile terminal in case said mobile terminal is located in a given zone, said packet transfer scheme being characterized in that:

• each of said first packet switches inquires of said database about the location information when it receives a packet addressed to said mobile terminal;
• said database provides each of said first packet switches with the location information in response to said inquiry;
• each of said first packet switches writes the location information provided from said database into its respective temporary storage means, and when said location information indicates said given zone, transfers said packet to said second packet switch, and when said packet addressed to said mobile terminal is received again after the initial reception of said packet, reads said location information from its temporary storage means and transfers said re-received packet to said second packet switch;
• said second packet switch transfers said packet to said mobile terminal when said second packet switch receives said packet from one of said first packet switches;
• said second packet switch requests each of said first packet switches to rewrite said location information when said location information is rewritten in said database;
• and
• each of said first packet switches renews its respective location information when said location information is stored in its corresponding temporary storage means.

A packet transfer scheme used in a mobile communication system comprising a database for storing an identification number of a mobile terminal and location information showing a zone in which said mobile terminal is currently located, and for rewriting said location information in accordance with a request from said mobile terminal, a plurality of first packet switches, each having a corresponding temporary storage means with a higher access speed than said database a second packet switch capable of communicating with said mobile terminal in case said mobile terminal is located in a given zone, said packet transfer scheme being characterized in that:

• each of said first packet switches inquires of said database about the location information when it receives a packet addressed to said mobile terminal;
• said database provides each of said first packet switches with the location information in response to said inquiry;
• each of said first packet switches writes the location information provided from said database into its corresponding temporary storage means, and when said location information indicates said given zone, transfers said packet to said second packet switch, and when said packet addressed to said mobile terminal is received again after the initial reception of said packet, reads said location information from its corresponding temporary storage means and transfers said re-received packet to said second packet switch;
• said second packet switch transfers said packet to said mobile terminal when said second packet switch receives said packet from one of said first packet switches;
• said database requests each of said first packet switches which previously stored said location information in its corresponding temporary storage means, to rewrite said location information when said location information is rewritten in said database;
• and
• each of said first packet switches, which received the rewrite request, renews its respective location information stored in its corresponding temporary storage means.

A packet transfer scheme used in a mobile communication system comprising a database for storing an identification number of a mobile terminal and location information showing a zone in which said mobile terminal is currently located, and for rewriting said location information in accordance with a request from said mobile terminal, a plurality of first packet switches, each having a corresponding temporary storage means with a higher access speed than said database, a second packet switch capable of communicating with said mobile terminal in case said mobile terminal is located in a given zone, said packet transfer scheme being characterized in that:

• each of said first packet switches inquires of said database about the location information when it receives a packet addressed to said mobile terminal;
• said database provides each of said first packet switches with the location information in response to said inquiry;
• each of said first packet switches writes the location information provided from said database into its corresponding temporary storage means, and when said location information indicates said given zone, transfers said packet to said second packet switch, and when said packet addressed to said mobile terminal is received again after the initial reception of said packet, reads said location information from its corresponding temporary storage means and transfers said re-received packet to said second packet switch;
• said second Packet switch transfers said packet to said mobile terminal when said second packet switch receives said packet from one of said first packet switches;
• said second packet switch requests each of said first packet switches which previously stored said location information in its corresponding temporary storage means, to rewrite said location information when said location information is rewritten in said database;
• and
• each of said first packet switches, which received the rewrite request, renews its respective location information stored in its corresponding temporary storage means.

A packet transfer scheme used in a mobile communication system comprising a database for storing an identification number of a mobile terminal and location information showing a zone in which said mobile terminal is currently located, and for rewriting said location information in accordance with a request from said mobile terminal, a plurality of first packet switches, each having a corresponding temporary storage means with a higher access speed than said database, a second packet switch capable of communicating with said mobile terminal in case said mobile terminal is located in a given zone, said packet transfer scheme being characterized in that:

• each of said first packet switches inquires of said database about the location information when it receives a packet addressed to said mobile terminal;
• said database provides each of said first packet switches with the location information in response to said inquiry;
• each of said first packet switches writes the location information provided from said database into its corresponding temporary storage means, and when said location information indicates said given zone, transfers said packet to said second packet switch, and when said packet addressed to said mobile terminal is received again after the initial reception of said packet, reads said location information from its corresponding temporary storage means and transfers said re-received packet to said second packet switch;
• said second packet switch transfers said packet to said mobile terminal when said second packet switch receives said packet from one of said first packet switches;
• said second packet switch sends a transfer impossible notice to said one of said first packet switches informing that a transfer of said packet is impossible to perform when said packet is transferred again from said one of said first packet switches after said mobile terminal moves outside said given zone;
• said one of said first packet switches, upon receipt of said transfer impossible notice, inquires of said database about a new location information of said mobile terminal;
• said database provides said one of said first packet switches with said new location information in response to said inquiry;
• and
• said one of said first packet switches writes said new location information in its corresponding temporary storage means upon receipt of said new location information from said database.