Wireless base station network system, contorl station, base station switching method, signal processing method, and handover control method
First Claim
1. A network system of radio base stations comprising base stations provided in a plurality of cells and a control station controlling the base stations, in which the base stations and the control station are connected by optical fibers using a wavelength multiplexing transmission method, wherein:
- the base station comprises a variable-wavelength transmitter for transmitting an optical signal having a predetermined wavelength, and an optical coupler for combining optical signals from the variable-wavelength transmitter in order to transmit the optical signals using the wavelength multiplexing transmission method;
the control station comprises a plurality of optical receivers for receiving wavelengths of the optical signals transmitted using the wavelength multiplexing transmission method, and an optical coupler for splitting the wavelength-multiplexed optical signals transmitted from the base stations to the optical receivers by wavelength; and
when the radio communication terminal communicating with the base station moves and changes the base station to communicate with, a new base station which communicates with the radio communication terminal after a movement of the radio communication terminal controls the wavelength of the variable-wavelength transmitter, and then transmits the optical signals to the control station with the same wavelength as one used for transmitting by a previous base station which communicates with the radio communication terminal before the movement.
1 Assignment
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Accused Products
Abstract
The present invention is a network system of radio base stations comprising base stations provided in a plurality of cells and a control station controlling the base stations, in which the base stations and the control station are connected by optical fibers using a wavelength multiplexing transmission method, wherein: the base station comprises a variable-wavelength transmitter for transmitting an optical signal having a predetermined wavelength, and an optical coupler for combining optical signals from the variable-wavelength transmitter in order to transmit the optical signals using the wavelength multiplexing transmission method, the control station comprises a plurality of optical receivers for receiving wavelengths of the optical signals transmitted using the wavelength multiplexing transmission method, and an optical coupler for splitting the wavelength-multiplexed optical signals transmitted from the base stations into the optical receivers by wavelength, and when the radio communication terminal communicating with the base station moves and changes the base station to communicate with, a new base station which communicates with the radio communication terminal after a movement of the radio communication terminal controls the wavelength of the variable-wavelength transmitter, and then transmits the optical signals to the control station with the same wavelength as one used for transmitting by a previous base station which communicates with the radio communication terminal before the movement.
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Citations
31 Claims
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1. A network system of radio base stations comprising base stations provided in a plurality of cells and a control station controlling the base stations, in which the base stations and the control station are connected by optical fibers using a wavelength multiplexing transmission method, wherein:
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the base station comprises a variable-wavelength transmitter for transmitting an optical signal having a predetermined wavelength, and an optical coupler for combining optical signals from the variable-wavelength transmitter in order to transmit the optical signals using the wavelength multiplexing transmission method;
the control station comprises a plurality of optical receivers for receiving wavelengths of the optical signals transmitted using the wavelength multiplexing transmission method, and an optical coupler for splitting the wavelength-multiplexed optical signals transmitted from the base stations to the optical receivers by wavelength; and
when the radio communication terminal communicating with the base station moves and changes the base station to communicate with, a new base station which communicates with the radio communication terminal after a movement of the radio communication terminal controls the wavelength of the variable-wavelength transmitter, and then transmits the optical signals to the control station with the same wavelength as one used for transmitting by a previous base station which communicates with the radio communication terminal before the movement. - View Dependent Claims (2, 3, 4, 5, 6, 10, 11, 12, 13, 14, 15, 17, 18, 19)
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7. A network system of radio base stations comprises base stations provided in a plurality of cells and a control station controlling the base stations, in which the base stations and the control station are connected by optical fibers with a sub-carrier optical transmission, wherein:
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the base station comprises a radio signal demodulator for mobile communication for demodulating radio signals for mobile communication received from the radio communication terminal and for converting the demodulated signals into digital signals, a variable-frequency entrance radio signal modulator for converting the signals converted by the radio signal demodulator for mobile communication into entrance radio signals, an optical receiver for converting radio signals transmitted from the control station or other base stations using the sub-carrier optical transmission method into electrical signals, and a coupler for combining an output of the optical receiver and an output of the variable-frequency entrance radio signals modulator;
the control station comprises;
an optical receiver for converting optical signals transmitted with the entrance radio signals using the sub-carrier optical transmission method into electrical signals, a selective-frequency coupler for splitting off the outputs from the optical receiver by frequency, and an entrance radio signal demodulator for converting each entrance radio signal split off by the selective-frequency coupler into digital signals; and
when the radio communication terminal communicating with the base station moves and changes the base station to communicate with, a new base station which communicates with the radio communication terminal after a movement of the radio communication terminal controls a carrier frequency of the variable-frequency entrance radio signals modulator, and transmits the entrance radio signals to the control station on the same frequency as one used for transmitting by a previous base station which communicates with the radio communication terminal before the movement. - View Dependent Claims (8, 9)
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16. A network system of radio base stations comprising a plurality of base stations communicating with radio communication terminals, a control station comprehensively controlling the base stations and communicating with an external communication network, and optical fiber lines connecting the base stations and the control station, in which each of the base stations receives signals transmitted by the radio communication terminal, converts the received signals into optical signals, and then transmits the converted optical signals to the control station via the optical fiber lines;
- wherein;
each of the base stations comprises a signal converting part for converting signals transmitted from the radio communication terminal into optical signals having different wavelengths assigned particularly to each of the sending radio communication terminals; and
the control station comprises an optical signal receiving part for receiving via the optical fiber lines near-simultaneously optical signals having an identical wavelength that are converted respectively by the signal converting part from signals transmitted from the same radio communication terminal and received by at least two base stations, and for converting the received signals into electrical signals to be output, and an equalizing part for equalizing the output signals. - View Dependent Claims (20, 21, 22)
- wherein;
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23. A control station which controls a network system of radio base stations comprising a plurality of base stations communicating with radio communication terminals, and optical fiber lines, further comprising:
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an optical signal receiving part for receiving via the optical fiber lines near-simultaneously optical signals having a different wavelength assigned particularly to each sending radio communication terminal that are converted respectively by the signal converting part from signals transmitted from an identical radio communication terminal and received by at least two base stations, and for converting the received signals into electric signals to be output; and
an equalizing part for equalizing the output signals.
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24. A method for switching of base stations in a network system of radio base stations comprising base stations provided in a plurality of cells and a control station controlling the base stations, in which the base stations and the control station are connected by optical fibers, wherein:
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a wavelength for transmission from the base station to the control station is set at the beginning of a communication between the base station and the radio communication terminal, and this wavelength for transmission is fixed while the radio communication terminal is communicating; and
even when the radio communication terminal moves and changes the base station to communicate with, a new base station which communicates with the radio communication terminal after a movement of the radio communication terminal transmits information from the radio communication terminal to the control station on the wavelength for transmission set for the radio communication terminal.
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25. A method for switching of base stations in a network system of radio base stations comprising base stations provided in a plurality of cells and a control station controlling the base stations, in which the base stations and the control station are connected by optical fibers, wherein:
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the control station comprises a variable-wavelength transmitter; and
a different wavelength for transmission from the control station to the base station is set for each base station, and when the radio communication terminal moves and changes the base station to communicate with, the control station controls a wavelength of the variable-wavelength transmitter and transmits information intended for the radio communication terminal to a new base station which communicates with the radio communication terminal after a movement of the radio communication terminal, on the wavelength for transmission set for a new base station which communicates with the radio communication terminal after the movement.
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26. A method for switching of base stations in a network system of radio base stations comprising base stations provided in a plurality of cells and a control station controlling the base stations, in which the base stations and the control station are connected by optical fibers, wherein:
a different wavelength for transmission from the control station to the base station is set for each base station, and when the radio communication terminal moves and changes the base station to communicate with, the control station transmits information of the radio communication terminal to a new base station which communicates with the radio communication terminal after a movement of the radio communication terminal on the wavelength for transmission set for a previous base station which communicates with the radio communication terminal before the movement.
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27. A method for switching of base stations in a network system of radio base stations comprising base stations provided in a plurality of cells and a control station controlling the base stations, in which the base stations and the control station are connected by optical fibers with a sub-carrier optical transmission, wherein:
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an entrance radio signal for a sub-carrier optical transmission from the base station to the control station is set at the beginning of a communication between the base station and a radio communication terminal, and the entrance radio signal is fixed while the radio communication terminal is communicating; and
even when the radio communication terminal moves and changes the base station to communicate with, a new base station which communicates with the radio communication terminal after a movement of the radio communication terminal transmits information of the radio communication terminal to the control station with the entrance frequency signal set for the radio communication terminal using the sub-carrier optical transmission method.
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28. A method for switching of base stations in a network system of radio base stations comprising base stations provided in a plurality of cells and a control station controlling the base stations, in which the base stations and the control station are connected by optical fibers with the sub-carrier optical transmission, wherein:
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a different entrance radio signal sent from the control station to the base station is set for each base station; and
when the radio communication terminal moves and changes the base station to communicate with, the control station transmits information intended for the radio communication terminal to a new base station which communicates with the radio communication terminal after a movement of the radio communication terminal with the entrance radio signal set for the new base station using the sub-carrier optical transmission method.
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29. A method for switching of base stations in a network system of radio base stations comprising base stations provided in a plurality of cells and a control station controlling the base stations, in which the base stations and the control station are connected by optical fibers with a sub-carrier optical transmission, wherein:
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a different entrance radio signal sent from the control station to the base station is set for each base station; and
when the radio communication terminal moves and changes the base station to communicate with, a new base station which communicates with the radio communication terminal after a movement of the radio communication terminal transmits information of the radio communication terminal to the control station using the sub-carrier optical transmission method with an entrance frequency signal set for a previous base station which communicates with the radio communication terminal before the movement.
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30. A method for signal processing in a network system of radio base stations comprising a plurality of base stations communicating with radio communication terminals, a control station comprehensively controlling the base stations and communicating with an external communication network, and optical fiber lines connecting the base stations and the control station, comprising the steps of:
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in each of the base stations, receiving signals transmitted from the radio communication terminal, converting the received signals into optical signals having different wavelengths assigned particularly to each of the sending radio communication terminals, and transmitting the converted signals to the control station via the optical fiber lines; and
in the control station, receiving via the optical fiber lines near-simultaneously optical signals having an identical wavelength that are converted from signals transmitted from the same radio communication terminal and received by at least two base stations, converting the received signals into electric signals, and equalizing the electric signals. - View Dependent Claims (31)
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Specification