RADIO ACCESS TERMINAL, BASE STATION CONTROLLER, AND HANDOFF CONTROL METHOD IN RADIO COMMUNICATION SYSTEM
First Claim
1. A handoff control method in a radio communication system having a plurality of radio terminals, a plurality of base stations which perform radio communications with the radio terminals, and a base station controller which controls the base stations, wherein radio frequencies with which the radio base stations communicate with the radio terminals are allowed to differ in the radio communication system, wherein:
- the radio terminal, which has positional information detection means, transmits positional information detected by the positional information detection means, to the base station controller through the radio base station communicating with the radio terminal;
a table is prepared beforehand in the base station controller, the table stores therein positional information items of the base stations, information items of frequencies used for transmissions/receptions to/from the radio terminals and decision conditions in handoff operations, as to the respective base stations connected to the base station controller itself; and
the base station controller selects, when the positional information is received from the radio terminal, the base station being a handoff candidate on the basis of the positional information of the radio terminal, the positional information items of the respective base stations and the decision condition in the handoff operation, with reference to the table, and transmits a handoff request message in which the information of the frequency of the base station being the handoff candidate is contained, to the radio terminal through the base station communicating with the radio terminal.
2 Assignments
0 Petitions
Accused Products
Abstract
In a radio communication system wherein radio frequencies for communicating with a radio terminal are different in radio base stations, a table in which positional information, information on the frequency used for transmission/reception to/from the terminal, and a decision condition in a handoff operation are stored as to each base station is prepared in a base station controller beforehand. When the positional information is received from the radio terminal, the base station controller selects the base station being a handoff candidate, on the basis of the positional information of the radio terminal, the positional information of each base station and the decision condition of the handoff operation with reference to the table, and it transmits a handoff request message which contains the information on the frequency of the base station being the handoff candidate, to the radio terminal through the base station communicating with the radio terminal.
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Citations
6 Claims
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1. A handoff control method in a radio communication system having a plurality of radio terminals, a plurality of base stations which perform radio communications with the radio terminals, and a base station controller which controls the base stations, wherein radio frequencies with which the radio base stations communicate with the radio terminals are allowed to differ in the radio communication system, wherein:
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the radio terminal, which has positional information detection means, transmits positional information detected by the positional information detection means, to the base station controller through the radio base station communicating with the radio terminal; a table is prepared beforehand in the base station controller, the table stores therein positional information items of the base stations, information items of frequencies used for transmissions/receptions to/from the radio terminals and decision conditions in handoff operations, as to the respective base stations connected to the base station controller itself; and the base station controller selects, when the positional information is received from the radio terminal, the base station being a handoff candidate on the basis of the positional information of the radio terminal, the positional information items of the respective base stations and the decision condition in the handoff operation, with reference to the table, and transmits a handoff request message in which the information of the frequency of the base station being the handoff candidate is contained, to the radio terminal through the base station communicating with the radio terminal. - View Dependent Claims (2)
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3. A radio terminal in a radio communication system having a plurality of base stations which perform radio communications with the radio terminal, and a base station controller which controls the base stations, wherein radio frequencies with which the radio base stations communicate with the radio terminal are allowed to differ in the radio communication system, the radio terminal comprises:
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positional information detection means; and means for altering a frequency for communication set at hardware within the radio terminal, wherein the radio terminal; cyclically transmits positional information detected by said positional information detection means to the base station controller through the radio base station communicating with the radio terminal; and alters, when the radio terminal receives a handoff request message in which information of the frequency of the base station of a handoff candidate is contained from the base station controller, the frequency for communication set at the hardware within the radio terminal by the means for altering, and receives a radio signal from the base station of the handoff candidate. - View Dependent Claims (4)
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5. A base station controller in a radio communication system having a plurality of radio terminals, a plurality of base stations which perform radio communications with the radio terminals, and the base station controller which controls the base stations, wherein radio frequencies with which the radio base stations communicate with the radio terminals are allowed to differ in the radio communication system, the base station controller comprises:
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a table storing therein positional information items of the base stations, information items of frequencies used for transmissions/receptions to/from the radio terminals and decision conditions in handoff operations, as to the respective base stations connected to the base station controller itself, wherein when the base station controller receives the positional information cyclically transmitted from the radio terminal, the base station controller selects the base station being a handoff candidate on the basis of the positional information of the radio terminal, the positional information items of the respective base stations and the decision condition in the handoff operation, with reference to the table, and transmits a handoff request message in which the information of the frequency of the base station being the handoff candidate is contained, to the radio terminal through the base station communicating with the radio terminal. - View Dependent Claims (6)
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Specification