We Claim:
1. A mobile communication system comprising:
at least one user equipment;
a plurality of base stations that perform radio communication with the at least one
user equipment; and
a radio network controller that controls the plurality of base stations, wherein
the radio network controller indicates a resource that is a radio resource for
transmitting to the user equipment a reference signal less frequently than normal to the
base stations, the reference signal being transmitted to measure power,
a base station of the plurality of base stations designates, in addition to the
resource indicated by the radio network controller, a resource that is a radio resource for
transmitting the reference signal to the user equipment less frequently than normal,
the base station transmits the reference signal to the user equipment less
frequently than normal in the resource indicated by the radio network controller and the
resource additionally designated by the base station itself, and
the user equipment receives the reference signal from the base station less
frequently than normal in the resource indicated by the radio network controller and the
resource additionally designated by the base station.
2. A base station that performs radio communication with user equipment in response to a
control by a radio network controller, wherein
the radio network controller indicates a low-frequency resource that is a radio
resource for transmitting to the user equipment a reference signal less frequently than
normal to the base station, the reference signal being transmitted to measure power,
the base station designates, in addition to the low-frequency resource indicated by
the radio network controller, a low-frequency resource that is a radio resource for
transmitting the reference signal to the user equipment less frequently than normal, and
the base station transmits the reference signal to the user equipment less
frequently than normal in the low-frequency resource indicated by the radio network
controller and the low-frequency resource additionally designated by the base station itself.
3. The base station as claimed in claim 2, wherein the base station notifies a neighbor base
station of the low-frequency resource additionally designated by the base station itself.
4. The base station as claimed in claim 2, wherein the base station notifies the radio network
controller of the low-frequency resource additionally designated by the base station itself.
5. The base station as claimed in claim 2, wherein the base station additionally designates the
low-frequency resource in addition to the low-frequency resource indicated by the radio
network controller depending on an operation state.
6. The base station as claimed in claim 5, wherein, when the base station operates in an
energy-saving mode having an operation power lower than a normal operation power, the
base station additionally designates the low-frequency resource in addition to the lowfrequency resource indicated by the radio network controller.
7. The base station as claimed in claim 2, wherein the low-frequency resource is a subframe to
transmit multimedia data of a radio frame.
8. A radio network controller that controls the plurality of base stations that perform radio
communication with user equipment, wherein
the radio network controller indicates a low-frequency resource that is a radio
resource for transmitting to the user equipment a reference signal less frequently than
normal to the base stations, the reference signal being transmitted to measure power, and
the radio network controller changes the low-frequency resource indicated to the
base station on the basis of a low-frequency resource additionally designated by the base
station.9. The radio network controller as claimed in claim 8, wherein the low-frequency resource is a
subframe to transmit multimedia data of a radio frame.
10. A user equipment that performs radio communication with a base station controlled by a
radio network controller, wherein
the user equipment receives a reference signal less frequently than normal in a
resource indicated by the radio network controller and a resource additionally designated by
the base station, the reference signal being received to measure power,
the user equipment performs a reception power measurement to determine a
reception quality of signals from the base stations,
the user equipment determines whether to connect to the base station based on
the reception quality determined, and
the user equipment connects to the base station based on a result of the
determination of reception quality,
wherein the resource indicated by the radio network controller is changed to
another resource based on the additionally designated resource by the base station, and the
changed resource is indicated to the user equipment.