Radio communication system
First Claim
1. A radio communication system comprising a base station for performing radio communication with a radio communication terminal;
- and a control station connected to the base station via an optical transmission line,said base station comprising;
a variable direction array antenna which comprises a plurality of antenna elements and which can change directivity in accordance with a position of said radio communication terminal;
a base station side frequency conversion unit configured to subject received signals received from said radio communication terminal via said plurality of antenna elements to frequency conversion to different bands;
a sub-carrier multiplexing signal generation unit configured to combine a plurality of signals subjected to the frequency conversion by said base station side frequency conversion unit to generate a sub-carrier multiplexing signal; and
a base station side transmission means configured to transmit optical signals generated by conducting optical modulation with respect to said sub-carrier multiplexing signal to said control station via said optical transmission line,said control station comprising;
a first optical/electric conversion unit configured to convert the optical signal transmitted from said base station into an electric signal;
a first branching unit configured to branch the electric signal to the signals received by the plurality of antennas;
control station side frequency conversion unit configured to perform the frequency conversion to obtain the signals of the same frequency band for each of the branched signals;
a beam calculation unit configured to obtain a weighting coefficient to control directivity of said plurality of antenna elements;
a weighting unit configured to perform weighting with respect to the branched signals of which frequencies have been converted by said control station side frequency conversion unit based on said weighting coefficient;
a combiner unit configured to combine the weighted signals; and
a received signal generation unit configured to demodulate the combined signals to generate a received signal.
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Accused Products
Abstract
There is disclosed a radio communication system in which a constitution of a base station and further a control station can be simplified. A radio communication system according to the present invention converts a received signal received by a plurality of antenna elements in a base station to a signal of different frequency band, and then conflates the converted signal in order to generate sub-carrier wave multiplex signal. The signal is converted to an optical signal, and then the optical signal is transmitted to a control station via an optical fiber. Or the control station performs weighting to phase of the transmitted signal transmitted from a plurality of antennas of a base station, and then performs frequency conversion to different frequency band, and then conflates the converted signal in order to generate the sub-carrier wave multiplex signal. The signal is converted to an optical signal, and then an optical signal is transmitted to the base station side via the optical fiber. The control station and the base station divides the received sub-carrier wave multiplex signal by each frequency band, and then the frequency of the divided signals are converted to the same frequency band in order to generate the transmitted/received signal of each antenna element. By such a constitution, it is possible to reduce constituent of the optical transmission components to the minimum and to simplify the constitution of the base station. Furthermore, it is possible to maintain the relative phase difference and the relative intensity of the transmitted/received signal of each antenna element. Because of this, it is possible to estimate an arrival direction of the received signal and to control radiation beam pattern of the transmitted signal.
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Citations
13 Claims
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1. A radio communication system comprising a base station for performing radio communication with a radio communication terminal;
- and a control station connected to the base station via an optical transmission line,
said base station comprising; a variable direction array antenna which comprises a plurality of antenna elements and which can change directivity in accordance with a position of said radio communication terminal; a base station side frequency conversion unit configured to subject received signals received from said radio communication terminal via said plurality of antenna elements to frequency conversion to different bands; a sub-carrier multiplexing signal generation unit configured to combine a plurality of signals subjected to the frequency conversion by said base station side frequency conversion unit to generate a sub-carrier multiplexing signal; and a base station side transmission means configured to transmit optical signals generated by conducting optical modulation with respect to said sub-carrier multiplexing signal to said control station via said optical transmission line, said control station comprising; a first optical/electric conversion unit configured to convert the optical signal transmitted from said base station into an electric signal; a first branching unit configured to branch the electric signal to the signals received by the plurality of antennas; control station side frequency conversion unit configured to perform the frequency conversion to obtain the signals of the same frequency band for each of the branched signals; a beam calculation unit configured to obtain a weighting coefficient to control directivity of said plurality of antenna elements; a weighting unit configured to perform weighting with respect to the branched signals of which frequencies have been converted by said control station side frequency conversion unit based on said weighting coefficient; a combiner unit configured to combine the weighted signals; and a received signal generation unit configured to demodulate the combined signals to generate a received signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- and a control station connected to the base station via an optical transmission line,
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9. A radio communication system comprising a base station including a variable direction array antenna which has a plurality of antenna elements and which can change directivity in accordance with a position of a radio communication terminal;
- and a control station connected to the base station via an optical transmission line,
said control station comprising; a control station side branching unit configured to branch a signal correlated with a transmitted signal transmitted to said radio communication terminal from said variable direction antenna for said plurality of antenna elements; a weighting unit configured to weight based on a weight control signal with respect to the signals of the respective antenna elements relating to the transmitted signal transmitted from said variable direction antenna to said radio communication terminal; a control station side frequency conversion unit configured to convert frequencies of the signals weighted by said weighting unit to respective different bands; a sub-carrier multiplexing signal generation unit configured to combine the respective signals converted to the different bands subjected to the frequency conversion by said control station side frequency conversion unit to generate a sub-carrier multiplexing signal; and a transmission unit configured to transmit optical signals generated by conducting optical modulation with respect to said sub-carrier multiplexing signal to said base station via said optical transmission line, said base station comprising; a base station side branching unit configured to convert the optical signals transmitted from said base station via said optical transmission line to electric signals, and branch the electric signals for said plurality of antenna elements; and a base station side frequency conversion unit configured to subject the respective signals branched by said base station side branching unit to the signals of the same frequency band, wherein said plurality of antenna elements transmit the respective signals subjected to the frequency conversion by said base station side frequency conversion unit to said radio communication terminal. - View Dependent Claims (10, 11, 12, 13)
- and a control station connected to the base station via an optical transmission line,
Specification