Mobile node

A hand-over method of performing a hand-over operation with respect to communications executed on a mobile IP network, comprising:

• a mobile node including a plurality of interface network devices mounted therein and is moving among a plurality of networks, monitoring a network quality based on at least one of an intensity and a radio bandwidth of a radio wave received by said network device;
• transmitting a care of address to an address registering destination in response to a state of said network quality before a communication is disconnected;
• receiving a response that indicates an update of said care of address in said address registering destination and keeping a function of receiving data from a network before being switched until said communication is disconnected;
• and
• performing a hand-over operation of changing a route of communication information after said care of address is transmitted and switching a connecting destination into a new network, wherein:
• a shortage threshold value for detecting a shortage of said radio bandwidth currently available and a recovery threshold value for detecting a recovery from said shortage of said radio bandwidth are provided, said recovery threshold value being higher than said shortage threshold value;
• if said radio bandwidth is lower than said shortage threshold value, said hand-over operation is executed according to a lower network quality;
• and
• if said radio bandwidth is higher than said recovery threshold value, said hand-over operation is executed according to a recovered network.

A mobile IP system for performing communications on a mobile IP network, comprising:

• a network device having a function of interfacing with networks;
• a mobile node having a network quality monitor to monitor a network quality based on at least one of an intensity and a radio bandwidth of a radio wave received by each of said network devices, a hand-over controller to perform a hand-over operation of transmitting a care of address to an address registering destination in response to a state of said network quality before a communication is disconnected, changing a route of communication information and switching a connecting destination into a new first network, and a network controller to receive a response that indicates an update of said care of address in said address registering destination and to keep a function of receiving data from a previous second network before being switched until said communication is disconnected;
• a home agent to receive said care of address and to recognize distribution and location of information destined for said mobile node;
• and
• a correspondent node being connected with a default router to receive said care of address and to transmit information through said second network until said communication is disconnected and communication data with said mobile node through said first network after said hand-over process, wherein:
• said network quality monitor includes a shortage threshold value determiner for detecting a shortage of said radio bandwidth currently available and a recovery threshold value for detecting a recovery from said shortage of said radio bandwidth, said recovery threshold value being higher than said shortage threshold value;
• said hand-over controller performs the hand-over operation accompanied with a lower network quality if said radio bandwidth is lower than said shortage threshold value;
• and
• said hand-over controller performs the hand-over operation accompanied with a recovered network if said radio bandwidth is higher than said recovery threshold value.

A mobile node for communication data on a mobile IP network, comprising:

• a network device having a function of interfacing with a plurality of different mobile IP networks;
• a network quality monitor to monitor each quality of said plurality of mobile IP networks, based on at least one of an intensity and a radio bandwidth of a radio wave received by said network device;
• and
• a hand-over controller to execute a hand-over operation of switching the mobile IP network being currently active in communication into another mobile IP network in response to a state of said each quality of said plurality of mobile IP networks, wherein:
• said network quality monitor includes a shortage threshold value determiner for detecting a shortage of said radio bandwidth currently available and a recovery threshold value for detecting a recovery from said shortage of said radio bandwidth, said recovery threshold value being higher than said shortage threshold value;
• said hand-over controller performs the hand-over operation accompanied with a lower network quality if said radio bandwidth is lower than said shortage threshold value;
• and
• said hand-over controller performs the hand-over operation accompanied with a recovered network if said radio bandwidth is higher than said recovery threshold value.