Mobile communication system using adaptive multi-antenna
First Claim
1. A mobile communication system using an adaptive multi-antenna, comprising:
- a wireless base station;
a wireless relay station; and
a mobile terminal station which performs communication with the wireless base station via the wireless relay station,wherein the wireless base station has a multi-antenna, anda multi-antenna communication method is switched to a closed loop method which uses feedback signals from the mobile terminal station, and an open-loop method which does not use the feedback signal according to estimation of the delay time of feedback signals from the mobile terminal station, andwherein the multi-antenna communication method to be switched further comprises a channel-tracking method which controls each antenna of the multi-antenna to track variations in a wireless propagation channel, and a direction-tracking method which forms directionality in an optimum transmission direction.
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Accused Products
Abstract
A mobile communication system using an adaptive multiantenna realizes improvement of reception characteristics, effective use of the band, and optimization of the throughput in comparison with a system in which application of the same multiantenna communication method is continued irrespective of a variation of the number of radio relay stations. The mobile communication system comprises a radio base station, a radio relay station, and mobile terminal stations for communicating with the radio base station through a radio relay station. The radio base station has a multiantenna and is characterized in that the radio base station judges if there is any variation of the number of radio relay stations when the radio base station carries out transmission through a radio relay station, and the radio base station communicates with the mobile terminal station by switching the multiantenna communication method using the multiantenna depending on the delay time of the feedback signal from the mobile terminal station if there is a variation of the number of radio relay stations.
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Citations
10 Claims
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1. A mobile communication system using an adaptive multi-antenna, comprising:
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a wireless base station; a wireless relay station; and a mobile terminal station which performs communication with the wireless base station via the wireless relay station, wherein the wireless base station has a multi-antenna, and a multi-antenna communication method is switched to a closed loop method which uses feedback signals from the mobile terminal station, and an open-loop method which does not use the feedback signal according to estimation of the delay time of feedback signals from the mobile terminal station, and wherein the multi-antenna communication method to be switched further comprises a channel-tracking method which controls each antenna of the multi-antenna to track variations in a wireless propagation channel, and a direction-tracking method which forms directionality in an optimum transmission direction. - View Dependent Claims (2, 4, 5)
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3. A mobile communication system using an adaptive multi-antenna, comprising:
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a wireless base station; a wireless relay station; and a mobile terminal station which performs communication with the wireless base station via the wireless relay station, wherein the wireless base station has a multi-antenna, a multi-antenna communication method is switched according to estimation of the delay time of feedback signals from the mobile terminal station, and wherein the delay time of feedback signals from the mobile terminal station corresponds to a delay time between a timing of measurement at the mobile terminal station used for the multi-antenna communication method, and a timing of multi-antenna transmission based on information on the results of the measurement which is fed back to the wireless base station.
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6. A wireless base station which performs communication with a mobile terminal station via a wireless relay station in a mobile communication system, and which has a multi-antenna, the wireless base station comprising:
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a judgment unit, when transmission is performed through the wireless relay station in the communication with the mobile terminal station, to judge whether there is a change in the number of the wireless relay stations; a delay time judgment unit to judge the delay time of feedback signals from the mobile terminal station; and a multi-antenna method selection unit, when the judgment unit judges that there is a change in the number of the wireless relay stations according to the delay time of feedback signals from the mobile terminal station, to switch a multi-antenna communication method that uses the multi-antenna, to a closed loop method which uses feedback signals from the mobile terminal station, and an open-loop method which does not use the feedback signal, wherein the multi-antenna method selection unit further selects, as the multi-antenna communication method to be switched, a channel-tracking method which controls each antenna of the multi-antenna to track variations fluctuations in a wireless propagation channel path, and a direction-tracking method which forms directionality in an optimum transmission direction. - View Dependent Claims (8, 9)
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7. A wireless base station which performs communication with a mobile terminal station via a wireless relay station in a mobile communication system, and which has a multi-antenna, the wireless base station comprising:
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a judgment unit, when transmission is performed through the wireless relay station in the communication with the mobile terminal station, to judge whether there is a change in the number of the wireless relay stations; a delay time judgment unit to judge the delay time of feedback signals from the mobile terminal station; and a multi-antenna method selection unit, when the judgment unit judges that there is a change in the number of the wireless relay stations according to the delay time of feedback signals from the mobile terminal station, to switch a multi-antenna communication method that uses the multi-antenna; a threshold value table in which is set a feedback signal delay time threshold value for switching the multi-antenna communication method; and a terminal mobility judgment unit to judge the mobility of the mobile terminal station, wherein the delay time threshold value set in the threshold value table is updated when the mobility of the mobile terminal station, judged by the terminal mobility judgment unit, changes.
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10. A wireless base station which performs communication with a mobile terminal station via a wireless relay station in a mobile communication system, and which has a multi-antenna, the wireless base station comprising:
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a judgment unit, when transmission is performed through the wireless relay station in the communication with the mobile terminal station, to judge whether there is a change in the number of the wireless relay stations; a delay time judgment unit to judge the delay time of feedback signals from the mobile terminal station; a multi-antenna method selection unit, when the judgment unit judges that there is a change in the number of the wireless relay stations according to the delay time of feedback signals from the mobile terminal station, to switch a multi-antenna communication method that uses the multi-antenna; a first antenna for direction tracking, configured by a set of a plurality of antennas placed at a placement interval which heightens the correlation between antennas; a second antenna for channel tracking, configured by a set of a plurality of antennas placed at a placement interval which lowers the correlation between antennas; an antenna switcher to perform switching between the first antenna and second antenna; and a communication control unit to control the antenna switcher so as to perform switching between the first antenna and second antenna corresponding to selection of channel tracking or direction tracking by the multi-antenna method selection unit, wherein the multi-antenna method selection unit selects, as the multi-antenna communication method to be switched, a channel-tracking method which controls each antenna of the multi-antenna to track variations fluctuations in a wireless propagation channel path, and a direction-tracking method which forms directionality in an optimum transmission direction.
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Specification