Router device, datagram transfer method and communication system realizing handoff control for mobile terminals

A router device, comprising:

• at least one first interface connected with a plurality of radio base stations each radio base station being capable of accommodating at least one mobile terminal;
• at least one second interface connected with a network;
• an information exchanging unit configured to exchange a routing protocol on a network layer, through the second interface;
• a memory unit configured to store information regarding a routing on the network layer based on the routing protocol exchanged by the information exchanging unit;
• a transfer unit configured to transfer datagram through the first interface according to the information regarding the routing on the network layer stored in the memory unit;
• a moving detection unit configured to detect a moving of the mobile terminal among the radio base stations;
• an information updating unit configured to update the information regarding the routing on the network layer stored in the memory unit when the moving of the mobile terminal is detected by the moving detection unit;
• and
• a switching unit configured to switch transmission of the datagram by the transfer unit during an updating processing by the information updating unit between a mode for continuing datagram transmission to a radio base station of an originally located site of the mobile terminal and a mode for stopping datagram transmission to a radio base station of an originally located site of the mobile terminal, according to a communication quality required for transfer of the datagram.

A router device, comprising;

• at least one first interface connected with a plurality of radio base stations, each radio base station being capable of accommodating at least one mobile terminal;
• at least one second interface connected with a network;
• an information exchanging unit configured to exchange a routing protocol on a network layer, through the second interface;
• a memory unit configured to store information regarding a routing on the network layer based on the routing protocol exchanged by the information exchanging unit;
• a transfer unit configured to transfer datagram through the first interface according to the information regarding the routing on the network layer stored in the memory unit;
• a moving detection unit configured to detect a moving of the mobile terminal among the radio base stations;
• an information updating unit configured to update the information regarding the routing on the network layer stored in the memory unit when the moving of the mobile terminal is detected by the moving detection unit;
• and
• a move over detection unit configured to detect a move over of mobile terminal to a radio base station connected with another router device;
• and
• a control unit configured to update the information regarding the routing on the network layer such that datagram destined to the mobile terminal is transferred to said another router device, and transmit a message for updating the information regarding the routing on the network layer to said another router device such that said another router device transfers the datagram to the mobile terminal, when the move over detection unit detects the move over of the mobile terminal.

A router device, comprising:

• at least one first interface connected with a plurality of radio base stations, each radio base station being capable of accommodating at least one mobile terminal;
• at least one second interface connected with a network;
• an information exchanging unit configured to exchange a routing protocol on a network layer through the second, interface;
• a memory unit configured to store information regarding a routing on the network layer based on the routing protocol exchanged by the information exchanging unit;
• a transfer unit configured to transfer datagram through the first interface according to the information regarding the routing on the network layer stored in the memory unit;
• a moving detection unit configured to detect a moving of the mobile terminal among the radio base stations;
• an information updating unit configured to update the information regarding the routing on the network layer stored in the memory unit when the moving of the mobile terminal is detected by the moving detection unit;
• and
• a move over detection unit configured to detect a move over of mobile terminal to a radio base station connected with another router device;
• and
• a control unit configured to update the information regarding the routing on the network layer such that datagram destined to the mobile terminal is transferred to a first virtual connection to said another router device which is dedicated for the mobile terminal, and exchange messages with said another router device such that said another router device can carry out a switching on a lower layer of the network layer between the first virtual connection and a second virtual connection from said another router to a radio base station of a visited site of the mobile terminal which is dedicated to the mobile terminal, when the move over detection unit detects the move over of the mobile terminal.