Method for determining a time for performing a vertical hand-off among IP-based heterogeneous wireless access networks

A method for determining an execution time of a vertical handoff between base stations having different wireless interfaces in a handoff among Internet Protocol (IP)-based wireless access networks, the method comprising the steps of:

• transmitting, by a base station, predetermined information to a multi-mode Mobile Terminal (MT), and requesting the MT to perform the handoff, the predetermined information including information for bicasting, which represents a method for transferring data among the base stations, information for an execution time period of the vertical handoff, identification information of partner base stations for the base station, and information for types of handoff protocols used in order to support IP mobility among the base stations;
• computing, by the multi-mode MT, first Received Signal Strength (RSS) information using the execution time period of the vertical handoff, the first RSS information representing an RSS threshold value of a home base station based on which the handoff must be performed before a link from the multi-mode MT to the home base station among the base stations is down;
• and
• determining, by the multi-mode MT, the execution time of the handoff, including an initialization process for determining to perform the handoff using both the first RSS information and RSS information values of the base stations.

A method for determining an execution time of a vertical handoff between a first base station and a second base station, which have different wireless interfaces, in a handoff among Internet Protocol (IP)-based wireless access networks, the method comprising the steps of:

• transmitting, by a multi-mode Mobile Terminal (MT), predetermined information to the first base station, the predetermined information including identification information of the second base station, and information for types of handoff protocols used to support mobility of the multi-mode MT among the IP-based networks;
• exacting, by the first base station, first time information, second time information, third time information, and bicasting information with reference to the identification information of the second base station and information for the types of the handoff protocols of the multi-mode MT, and transmitting the extracted information to the multi-mode MT, the first time information representing a data transfer time information between the first base station and the second base station, the second time information representing information on a time period for which handoff signaling is to be performed between the first base station and the second base station, the third time information representing an average data transmission time information between the multi-mode MT and a base station, which corresponds to a target base station of the first base station and the bicasting information representing bicasting information of a base station, which corresponds to a home base station of the first base station and the second base station;
• computing, by the multi-mode MT, fourth time information with reference to transmission mode information, the first time information, the second time information, the third time information, and the bicasting information, the transmission mode information representing whether the multi-mode MT is in a transmission mode or in a reception mode, the fourth time information representing an execution time period of the handoff between the first base station and the second base station;
• computing, by the multi-mode MT, first Received Signal Strength (RSS) information with reference to the fourth time information, the first RSS information representing an RSS threshold value of the home base station based on which the handoff must be performed before a link from the multi-mode MT to the base station is down, which corresponds to the home base station of the first base station and the second base station, is down;
• and
• determining, by the multi-mode MT, the execution time of the handoff, including an initialization process for determining to perform the handoff with reference to the first RSS information, second RSS information representing an RSS value of the first base station, and third RSS information representing an RSS value of the second base station.