WE CLAIM:
1. A communication system comprising:
a base station device; and
at least one terminal device configured to be connected to the base station 5 device so as to perform radio communication with the base station device, wherein
the base station device is configured to control a plurality of base station beams having different beam directions,
the base station device transmits a reference signal through a corresponding base station beam, the reference signal being specific to each of the plurality of base 10 station beams used by the at least one terminal device to measure reception quality of a signal from the base station device,
the at least one terminal device notifies the base station device of terminal beam
related information, the terminal beam related information concerning at least one
terminal beam formed by the at least one terminal device, and
15 the base station device controls transmission of the reference signal through the
plurality of base station beams, based on the terminal beam related information.
2. The communication system according to claim 1, wherein the terminal beam related information includes information about a number of 20 the at least one terminal beam formed by the at least one terminal device, and
the base station device determines a number of times of transmission of the
reference signal through the plurality of base station beams, according to a largest number
of the at least one terminal beam.
25 3. The communication system according to claim 2, wherein
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the terminal beam related information further includes information about beam selection capability, the beam selection capability indicating a number of the at least one terminal beam that can be simultaneously received by the at least one terminal device, and
the base station device determines a number of times of transmission of the 5 reference signal through the plurality of base station beams, according to the largest number of the at least one terminal beam and the beam selection capability.
4. The communication system according to any one of claims 1 to 3, wherein
when the at least one terminal device completes selection of one of
10 combinations of the at least one terminal beam of the at least one terminal device and the plurality of base station beams, the at least one terminal device notifies the base station device of beam selection complete, and
the base station device re-determines a number of times of transmission of the reference signal through the plurality of base station beams, excluding a terminal device
15 that has already notified the base station device of the beam selection complete.
5. The communication system according to any one of claims 1 to 4, wherein
the at least one terminal device notifies the base station device of a movement
speed of the at least one terminal device, and
20 the base station device determines a transmission interval of the reference signal
through the plurality of base station beams for each of the at least one terminal device, according to the movement speed.
6. The communication system according to any one of claims 1 to 5, wherein
25 the base station device has an operation mode, the operation mode being a
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mode in which a transmission time period and a transmission interval of the reference signal through the plurality of base station beams are configured to be constant irrespective of the terminal beam related information, and
the at least one terminal device controls scanning of the at least one terminal 5 beam of the at least one terminal device, in accordance with a number of times of transmission and the transmission interval of the reference signal that are configured to be constant.
7. The communication system according to any one of claims 1 to 6, wherein
10 the base station device performs communication with a beam control
unsupported terminal device without performing control of the plurality of base station beams, the beam control unsupported terminal device not including a function of controlling a plurality of terminal beams.
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