Technical Field
[OOOl]
The present disclosure relates to a communication control device, a
10 communication control method, and a terminal device.
Background Art
[0002]
As the amount of communication data has been rapidly increasing due to the
15 proliferation of smartphones in recent years, further expansion of system capacities
in cellular communication has been required. To this end, in Release 12 of Third
Generation Partnership Project (3GPP), a new architecture for small cells is being
currently discussed. In this new architecture, in a small cell disposed within a
macrocell, a different frequency band from a frequency band used in the macrocell is
20 used. Accordingly, an advantage of division of cells can be obtained more
efficiently.
[0003]
Topics of discussion with regard to small cells include reduction of power
consumption of a base station in a small cell. To this end, for example, causing a
25 base station in a small cell to activate or to be in an idle state (dormant) depending on
a state of use of the small cell is considered. As an example, data traffic is
extremely small at night in office regions. As another example, in sport stadiums,
data traffic is extremely heavy in a specific time zone when an evcnt takcs place, but
is extremely light in other time zones. As still another example, a base station
30 installed in a home for the purpose of off-loading is not used in most time zones in
many cascs. As small cells become more widespread and the number of small cells
becomes extremely large from now on, the extremely huge amount of overall power
consumption can be reduced by cutting power consumption ol'base stations of small
cells. To this end, technologies for reducing power consumption of base stations of
small cells have been proposed.
5 [0004]
For example, Patent Literature 1 and Patent Literature 2 disclose
technologies in which, when it is determined that there is no radio communication
terminal in the vicinity of a femtocell, a base station in the femtocell is set to stop
receiving radio waves, and when it is determined that there is a radio communication
10 terminal in the vicinity of a femtocell, a base station in the femtocell is set to start
receiving radio waves. In addition, Patent Literature 3 discloses a technology in
I which, based on a position of a mobile terminal device which is obtained through the
I
I Global Positioning System (GPS), a small cell which can process communication of
I i the mobile terminal device is specified and power supply to the specified small cell is
I
I 15 resumed.
Citation List
Patent Literature
[0005]
20 Patent Literature 1: JP 201 1-049859A
Patent Literature 2: JP 201 1-049890A
Patent Literature 3: JP 201 1-091 748A
Summary of Invention
25 Technical Problem
[0006]
In the technologies disclosed in Patent Literatures 1 to 3 mentioned above,
however, since a small cell to activate is selected based only on a position of a
terminal device (or an area in which the position of the device is included), it is hard
30 to guarantee that a proper small cell is selected. For cxample, even when a base
station of a certain small cell is closer to a terminal devicc, there is also a possibility
of a channel between the base station and the terminal device being unfavorable due
to a large obstacle placed between the base station and the terminal device, or the
like. For this reason, while a base station of a small cell that is closer to a terminal
device is activated, quality of radio communication between the terminal device and
5 the base station can be lowered. As a result, for example, convenience of the user
of the terminal device declines.
[0007]
Therefore, it is desirable to provide a mechanism which can suppress
deterioration in communication quality of radio communication in a small cell while
10 power consumption of a base station of the small cell is reduced.
Solution to Problem
[OOOS]
According to the present disclosure, there is provided a communication
15 control device including: an acquisition unit configured to acquire a result of
measurement performed by a terminal device with regard to one or more small cells
which are partly or entirely overlapped by a macrocell; and a selection unit
configured to select a base station which is not to be set in an idle state from base
stations of the one or more small cells based on the result of the measurement.
20 [0009]
According to the present disclosure, there is provided a coillmunication
control method including: acquiring a result of measurement performed by a terminal
device with regard to one or more small cells which are partly or entirely overlapped
by a macrocell; and selecting, using a processor, a base station which is not to be set
25 in an idle state from base stations of the one or more small cells based on the result
of the measurement.
[OOlO]
According to the present disclosure, there is provided a communication
control device including: a communication control unit configured to control
30 transmission of a signal for measurement performed by a terminal device with regard
to a small cell which is partly or entirely overlapped by a macrocell; and a state
control unit configured to refrain from causing a base station of the small cell to be in
an idle state when the base station of the small cell is selected as a base station that is
not to be set in the idle state based on a result of the measurement.
[OOll]
5 According to the present disclosure, there is provided a terminal device
including: an acquisition unit configured to acquire a result of measurement with
regard to one or more small cells which are partly or entirely overlapped by a
macrocell; and a providing unit configured to provide the result of the measurement
to a communication control device which selects a base station which is not to be set
10 in an idle state from base stations of the one or more small cells based on the result
of the measurement.
Advantageous Effects of Invention
[00 121
15 According to the present disclosure described above, degradation in
communication quality of radio communication in a small cell can be suppressed
while power consumption of a base station of the small cell is reduced. Note that
the above-described effects are not necessarily limitative, and along with or instead
of the effects, any effect which is expected to be introduced in the present
20 specification or other effects which can be understood from the present specification
may be exhibited.
Brief Description of Drawings
[OO13]
25 [FIG. 11 FIG. 1 is an illustrative diagram showing an example of a schematic
configuration of a communication system according to an embodiment of the present
disclosure.
[FIG. 21 FIG. 2 is a block diagram showing an example of a configuration of a macro
base station according to an embodiment.
30 [FIG. 31 FIG. 3 is a descriptive diagram for describing an example of small cell
infornlation according to an embodiment.
[FIG. 41 FIG. 4 is an illustrative diagram for describing an example of carrier
aggregation according to an embodiment.
[FIG. 51 FIG. 5 is a block diagram showing an example of a configuration of a small
base station according to an embodiment.
5 [FIG. 61 FIG. 6 is a block diagram showing an cxample of the configuration of a
terminal device according to an embodiment.
[FIG. 71 FIG. 7 is a flowchart showing a first example of a schematic flow of a
communication control process according to an embodiment.
[FIG. 81 FIG. 8 is a flowchart showing a second example of a schematic flow of a
10 communication control process according to an embodiment.
[FIG. 91 FIG. 9 is a block diagram showing a first example of a schematic
configuration of an eNB.
[FIG. 101 FIG. 10 is a block diagram showing a second example of a schematic
configuration of an eNB.
15 [FIG 111 FIG. 11 is a block diagram showing an example of a schematic
configuration of a smartphone.
[FIG. 121 FIG. 12 is a block diagram showing an example of a schematic
configuration of a car navigation device.
20 Description of Embodiments
[00 141
Hereinafter, preferred embodiments of the present disclosure will be
described in detail with reference to the appended drawings. Note that, in this
25 specification and the appended drawings, structural elements that have substantially
the same function and structure are denoted with the same reference numerals, and
repeated explanation of these structural elements is omitted.
I
[0015]
In addition, in the present specification and drawings, there are cases in
30 which a plurality of constituent elements with substantially the same functional
configuration are distinguished by affixing different letters to the end of the same
reference numerals. For example, a plurality of constitutions with substantially the
same functional conf guration are distinguished as in the case of terminal devices
300A, 300B, and 300C, when necessary. However, when it is not particularly
necessary to distinguish a plurality of constituent elements with substantially the
5 same functional configuration, only the same reference numeral is given thereto.
For example, when it is not particularly necessary to distinguish the terminal devices
300A, 300B, and 300C, they are referred to simply as terminal devices 300.
[0016]
Note that description will he provided in the following order.
10 1. Outline of a configuration of a communication system according to an
embodiment
2. Configuration of a macro base station
3. Configuration of a small base station
4. Configuration of a terminal device
5. Process flow
6. Modified examples
7. Application examples
8. Conclusion
[0017]
20 <>
First, an outline of a configuration of a communication system 1 according
'I to an embodiment of the present disclosure will be described with reference to FIG. 1.
'I
i FIG. 1 is an illustrative diagram showing an example of a schematic configuration of 1 25 the communication system 1 according to the present embodiment. Referring to
FIG. 1, the communication system 1 includes a base station 100 of a macrocell 10
(which will be referred to hereinafter as a "macro base station"), base stations 200 of
I small cells 20 (which will be referred to hereinafter as "small base stations"), and
i
I terminal devices 300. The cominuuication system 1 is a system which conforn~sto ,
1
30 for example, Long Term Evolution (LTE), LTE-Advanced, or a coinmunication
scheme equivalent thereto. In addition, each small cell 20 is partly or entirely
overlapped by the macrocell 10.
[00 181
The macro base station 100 performs radio communication with the
terminal devices 300 positioned within the macrocell 10. In addition, the small base
5 stations 200 perform radio communication with the terminal devices 300 positioned
within the small cells 20. For example, in the small cells 20, a different frequency
band from the frequency band used in the macrocell 10 is used. That is, a
frequency band used by the small base stations 200 for radio communication in the
small cells 20 is different from the frequency band used by the macro base station
1.0 100 for radio communication in the macrocell 10. These frequency bands
! respectively include, for example, one or more component carriers (CCs). A CC is
a band used in carrier aggregation of LTE-Advanced.
I
I [00 191 1 Iu addition, particularly in the present embodiment, the small base stations
15 200 can be in an idle state (dormant). The small base stations 200 in the idle state
do not perform, for example, transmission in the downlink and reception in the
uplink. In other words, the small base stations 200 in the idle state stop
transmission in the downlink and reception in the uplink. In addition, even from the
idle state, the small base stations 200 can be activated thereafter and perform
20 transmission in the downlink and reception in the uplink.
[0020]
The terminal devices 300 perform radio communication with the macro base
station 100 when the devices are positioned within the macrocell 10. In addition,
the terminal devices 300 perform radio communication with small base stations 200
I / 25 when the devices are positioned within the small cells 20.
! :!
I
I [0021]
i
j In addition, the terminal devices 300 can perform radio communication
using, for example, one principal frequency band and one or more auxiliary
frequency bands. To be more specific, the terminal devices 300 have, for example,
I 30 the capability of carrier aggregation, and thus can perform radio co~nmunication
using one primary component carrier (PCC) and one or more secondary component
carriers (SCCs). Furthermore, the tcrminal devices 300 can perform radio
communication with the macro base station 100 and the small base stations 200 by
using a frequency band (CC) that is set for the macrocell 10 as a principal frequency
band (PCC) and a frequency band (CC) that is set for the small cells 20 as an
5 auxiliary frequency band (SCC).
I00221
112. Configuration or a macro base station>>
An example of a configuration of the macro base station 100 according to
the present embodiment will be described with reference to FIGS. 2 to 4. FIG. 2 is
10 a block diagram showing an example of a configuration of the macro base station
100 according to the present embodiment. Referring to FIG. 2, the macro base
station 100 includes an antenna unit 110, a radio communication unit 120, a network
communication unit 130, a storage unit 140, and a processing unit 150.
[0023]
15 (Antenna unit 110)
The antenna unit 110 receives radio signals and outputs the received radio
signals to the radio communication unit 120. In addition, the antenna unit 110
transmits transmission signals output by the radio communication unit 120.
[0024]
20 (Radio communication unit 120)
The radio communication unit 120 performs radio communication with the
terminal devices 300 positioned within the macrocell 10. For example, the radio
communication unit 120 performs radio communication with the terminal devices
300 using a frequency band that is set for the macrocell 10. The frequency band
25 includes, for example, one or more CCs.
~00251
(Network communication unit 130)
The network communication unit 130 communicates with other
communication nodes. For example, the network communication unit 130
30 communicates with the small base stations 200. In addition, the network
communication unit 130 communicates with, for example, other macro base stations
100. In addition, the network communication unit 130 communicates with, for
example, core network nodes.
[0026]
(Storage unit 140)
5 The storage unit 140 stores programs and data for operations of the macro
base station 100.
[0027]
For example, the storage unit 140 stores information relating to the small
base stations 200. The information includes, for example, small cell IDS of the
small cells 20 formed by the small base stations 200, position information that
indicates the positions of the small base stations 200, frequency channel information
that indicates a frequency channel on which reference signals are transmitted by the
small base stations 200, time information that indicates a time taken for the small
base stations 200 to start transmission of the reference signals from the idle state, and
the like.
[0028]
(Processing unit 150)
The processing unit 150 provides various functions of the macro base
station 100. The processing unit 150 includes a position information acquisition
unit 151, a first selection unit 152, an information providing unit 153, a small cell
control unit 154, a measurement result acquisition unit 155, a second sclcction unit
156, and a communication control unit 157.
[0029]
(Position information acquisition unit 15 1)
The position information acquisition unit 151 acquires position information
that indicates a position of each terminal device 300.
[0030]
For example, the position infomation acquisition unit 151 transmits a
position information requesting message that requests provision of position
inlormation that indicates the position of each terminal device 300 to the terminal
device 300 via the radio communication unit 120. Then, the terminal device 300
transmits the position information, and the position information acquisition unit 151
acquires the position information via the radio communication unit 120. As an
example, the position information requesting messagc may be an RRC connection
reconfiguration message.
[003 I]
Note that the position information acquisition unit 151 may acquire the
position information through positioning of the terminal device 300 using an uplink
signal (for example, a reference signal) transmitted from the terminal device 300,
instead of being provided with position information from the terminal device 300 as
described above. The positioning may be positioning based on a timing advance
(TA) value and an angle of arrival (AoA) with respect to the terminal device 300, or
may be positioning of the terminal device 300 performed by a plurality of macro
base stations 100.
[0032]
(First selection unit 152)
The first selection unit 152 selects one or more small cells 20 based on the
position information indicating the position of the terminal device 300.
[0033]
For example, the first selection unit 152 selects one or more small cells 20
neighboring the position of the terminal device 300 indicated by the position
information from tlic small cells 20 which are partly or entirely overlapped by the
macrocell 10. As an example, the first selection unit 152 selects small cells 20 of
the small base stations 200 present in a predetermined distance from the terminal
device 300.
[0034]
Accordingly, for example, a small base station 200 having a possibility of
performing radio communication with the terminal device 300 is selected, and a
small base station 200 having no possibility of performing radio communication with
the terminal device 300 is not selected. As a result, power consumption can be
further reduced.
[0035]
(Information providing unit 153)
The transmission control unit 152 provides information regarding the one or
more small cells 20 (which will be referred to hereinafter as "small cell information")
to the terminal device 300.
5 [0036]
For example, the small cell information includes the IDS of the one or more
small cells 20 (which will be referred to hereinafter as "small cell IDS"). As an
example, each small cell ID is an E-UTRAN Cell Global ID (ECGI). An ECGI is a
combination of a public land mobile network (PLMN) ID and a cell ID. In addition,
10 a PLMN is a combination of a country code and an operator code, and is an identiiier
of a public network. With such a small cell ID, the terminal device 300 can identify
the selected small cell 20.
[0037]
In addition, the small cell information includes, for example, information
15 that indicates a frequency channel on which signals for measuring (measurement)
(which will be referred to hereinafter as "measurement signals") are transmitted by
each of the small base stations 200 of the one or more small cells 20 (which will be
referred to hereinafter as "frequency channel information"). As an example, the
frequency channel information is an E-UTRA Absolute Frequency Channel Number
20 (EARFCN). Accordingly, for example, the terminal device 300 can receive the
measurement signals without searching for a frequency channel on which the
measurement signals are transmitted. For this reason, a load of measurement on the
terminal device 300 can be lightened.
[0038]
25 In addition, the small cell information includes, for example, information
that indicates timings at which the measurement signals are transmitted by each of
the small base stations 200 of the one or inore small cells 20 (which will be referred
to hereinafter as "timing information"). As an example, the timing information is a
system frame number (SFN) or a combination of an SFN and a subframe number.
30 Accordingly, the terminal device 300 can, for example, start receiving signals at
timings at which the measurement signals are transmitted. That is, the terminal
device 300 does not have to continuously receive signals over a long period of time.
For this reason, a load of measurement on the terminal device 300 can be lightened.
[0039]
In addition, each of the timings at which the measurement signals are
transmitted depends on, for example, time taken for each of the small base stations
200 of the one or more small cells 20 to be activated from the idle state. For
example, the information providing unit 153 decides each of the timings, taking the
time taken for each of the small base stations 200 of the one or more small cells 20 to
be activated from the idle state into consideration, and provides information that
indicates the decided timing (timing information). Accordingly, it is possible to
notify the terminal device 300 of a proper transmission timing even when time taken
to he activated from the idle state is different from the small base stations 200 of the
one or more small cells 20.
[0040]
As described above, the small cell information is provided to the terminal
device 300. Accordingly, a load of measurement on the terminal device 300 can be
lightened. A specific example of the small cell information will be described with
reference to FIG. 3.
[0041]
FIG. 3 is a descriptive diagram for describing an example of the small cell
information accordilig to the present embodiment. Referring to FIG. 3, the small
cell information in the form of a list is shown. As described above, the small cell
information includes small cell IDS, frequency channel information, and timing
information of the respective small cell 20.
[0042]
Note that the measurement information is, for example, a reference signal.
As an example, the measurement information is a cell-specific reference signal
(CRS) or a common reference signal (CRS).
[0043]
(Small cell control unit 154)
The small cell control unit 154 controls the small base stations 200 of the
one or more small cells 20.
[0044]
- Control over transmission of a measurement signal
The small cell control unit 154 causes, for example, the small base stations
5 200 of the one or more small cells 20 to transmit measurement signals.
[0045]
To be more specific, the small cell control unit 154 causes the small base
stations 200 of the one or more small cells 20 to be activated. As an example, the
small cell control unit 154 transmits an activation instruction message for instructing
10 the small base stations 200 of the one or more small cells 20 to be activated via the
network communication unit 130. Then, the small base stations 200 of the one or
more small cells 20 are activated and resume transmission of downlink signals
includ'mg measurement signals. As described above, the measurement signals are,
for example, reference signals.
15 100461
Accordingly, even when the small base stations 200 are in the idle state and
thus in a state in which downlink transmission is not performed, measurement with
respect to the one or more small cells 20 can be performed thereafter.
[0047]
20 In addition, the small cell control unit 154 causes, for example, the small
base stations 200 of (11c one or more small cells 20 to transmit measurement signals
at transmission timings that are notified of in the small cell information. As an
example, information indicating the transmission timings is included in the activation
instruction message, and the small base stations 200 resume transmission of
25 reference signals (or downlink signals including the reference signals) at the timings.
[0048]
Note that the small base stations 200 of the one or more small cells 20 may
only resume transmission in the downlinlz and stop reception in thc uplink.
[0049]
30 More control of the small cell control unit 154 will be described after
description of the measurement result acquisition unit 155 and the second selection
unit 156.
[0050]
(Measurement result acquisition unit 155)
Thc measurement result acquisition unit 155 acquires the result of
measurement (which will be referred to hereinafter as "measurement result") by ihe
terminal devices 300 with regard to the one or more small cells 20.
LO0511
For example, when each terminal device 300 completes measurement with
regard to ihe one or more small cells 20, the terminal device provides the result of the
measurement (i.e., measurement result) to the macro base station 100, and ihe
measurement result acquisition unit 155 acquires the measurement result via the
radio communication unit 120. As an example, the measurement result is provided
as a measurement report.
[0052]
The measurement result includes, for example, information regarding
reception power or quality of a measurement signal. To be more specific, the
measurement signal is, for example, a reference signal as described above. In
addition, the information regarding reception power or quality of the measurement
signal is, for example, reference signal received power (RSRP) or reference signal
received quality (RSRQ).
[0053]
In addition, the measurement result is, for example, information regarding
part of the one or more small cells 20. To be more specific, the measurement result
is, for example, information regarding the small cells 20 accompanied with RSRP or
RSRQ that satisfies a predetermined condition (for example, RSRP or RSRQ which
exceeds a predetermined threshold value). As an example, the measurement result
includes RSRP or RSRQ which satisfies a predetermined condition and the small cell
IDS of the small cells 20 accompanied with the RSRP or RSRQ. By providing the
information regarding the part of the small cells 20 as the measurement result in this
30 manner, lor example, overhead caused by transmission of the measurement result can
be suppressed.
I00541
Note that the measurement result may be information regarding each of the
one or more small cells 20.
[0055]
5 In addition, when the reception power or quality of the measurement signal
with regard to all of the one or more small cells 20 does not exceed the
predetermined threshold value, the measurement result may include information
indicating that the reception power or the quality does not exceed the predetermined
threshold value for all of the small cells. By providing such simple information as
10 the measurement result, for example, overhead caused by transmission of the
measurement result can be suppressed.
[0056]
(Second selection unit 156)
The second selection unit 156 selects a small base station 200 that will not
be set in the idle state from the small base stations 200 of the one or more small cells
20 based on the measurement result. In other words, the second selection unit 156
selects a small base station 200 that is in a state in which the small base station can
communicate with the terminal devices 300 from the small base stations 200 of the
one or more small cells 20 based on the measurement result.
[0057]
As described above, the measurement result includes, for example,
information regarding reception power or quality of the measurement signal. Then,
the second selection unit 156 selects the small base station 200 of the small cell 20
that brings the most satisfactory reception power or quality from the small base
stations 200 of the one or more small cells 20 as a small base station 200 that will not
be set in the idle state. Alternatively, the second selection unit 156 may select small
base stations 200 of two or more small cells 20 that bring more satisfactory reception
power or quality, instead of the small base station 200 of the small cell 20 that brings
the most satisfactory reception power or quality.
[0058]
As described above, a small base station 200 that will not be set in the idlc
state (i.e., a small base station 200 that is in the state in which the small base station
can communicate with the terminal devices 300) is selected based on the
measurement result. Accordingly, a small base station 200 which brings more
satisfactory communication quality is selected as a small base station 200 that will
not be set in the idle state, rather than, for example, selecting a small base station 200
that is closer to the terminal devices 300. For this reason, while power consumption
of the small base stations 200 is reduced, degradation of communication quality of
radio communication oftbe small cells 20 can be suppressed.
[0059]
Note that, when a demand for performing radio communication in the small
cclls 20 is notified of by the terminal device 300, the second selection unit 156
selccts the small base station 200 that will not be set in the idle state. For example,
not only the second selection unit 156, but also the first selection unit 152, the
information providing unit 153, the small cell control unit 154, and the measurement
result acquisition unit 155 perform the above-described operation only when the
units are notified of the demand. Therefore, when the terminal device 300 does not
perform radio communication in the small cells 20, the series of operations described
above is not performed. Accordingly, useless operations, for example, can be
omitted. In addition, the terminal device 300 can be allowed to perform radio
communication in the small cells 20, for example, according to a demand of the
terminal device 300.
[0060]
(Small cell control unit 154 - continued)
Next, control of the small cell control unit 154 will be further described.
[0061]
- Control over idling (dormancy) of a small base station
The small cell control unit 154 sets, for example, small base stations 200
other than the small base station 200 selected among the small base stations 200 of
the one or more small cells 20 to be in the idle state, rather than setting the selected
small base station 200 to be in the idle state.
[0062]
For example, since the small base stations 200 of the one or more small cells
20 have been activated for transmission of thc measurement signals as described
above, the small cell control unit 154 resets small base stations 200 other than the
selected small base station 200 among the small base stations 200 (which will be
5 referred to hereinafter as "other small base stations 200") to be in the idle state. In
this case, the small cell control unit 154 transmits, for example, an idling instruction
message for instructing the other small base stations 200 to be in the idle state via the
network communication unit 130. Then, the other small base stations 200 enter the
idle state, and do not perform transmission in the downlink and reception in the
10 uplink. On the other hand, the selected small base station 200 is not in thc idle state
and performs transmission in the downlink and reception in the uplink. The small
base station 200 is kept in the state in which the station can communicate with the
terminal devices 300.
[0063]
Note that the small base stations 200 of the one or more small cells 20 may
only resume transmission in the downlink and may not resume reception in the
uplink for transmission of measurement signals as described above. In this case, the
small cell control unit 154, for example, transmits the activation instruction message
for instructing the selected small base station 200 to be activated while transmitting
the idling instruction message to the other small base stations 200 as described above.
As a result, the selectcd small base station 200 also resumes reception in the uplink.
100641
In addition, the small base stations 200 of the one or more small cells 20
may be temporarily activated during transmission of measurement signals, and return
to the idle state again after the transmission of measurement signals. In this case,
the small cell control unit 154, for example, transmits the activation instruction
message for instructing activation to the selected small base station 200. Then, the
selected small base station 200 is activated and resumes transmission in the downlink
and transmission in the uplink.
100651
As a result of the control described above, the selected small base station
200 is in the state in which the station can communicate with the terminal devices
300, rather than in the idle state, and the other small base stations 200 are in the idle
state. Accordingly, the terminal devices 300 can perform radio communication in
the small cells 20, and power consumption of the small base stations 200 can be
5 reduced.
[0066]
(Communication control unit 157)
The communication control unit 157 controls radio communication in the
macrocell 10. In addition, the communication control unit 157 also controls, for
10 example, radio cominunication in the small cells 20 by controlling the small base
stations 200 or the terminal devices 300.
[0067]
Particularly in the present embodiment, the communication control unit 157
controls, for example, the terminal devices 300 to use a frequency band for the
15 macrocell 10 as one principal frequency band and to use a frequency band for the
small cell 20 of the small base station 200 to be selected as one of one or more
auxiliary frequency bands.
[0068]
To be more specific, the communication control unit 157 controls the
20 terminal devices 300 to, for example, use a CC for the macrocell 10 as a PCC and
use a CC for the sniall cell 20 as an SCC. As an example, the communication
control unit 157 transmits an RRC connection reconfiguration message for adding a
CC used by the selected small base station 200 as an SCC to the terminal devices 300
via the radio con~municationu nit 120. Then, the terminal devices 300 add the CC
25 as an SCC, and transmit an RRC connection reconfiguration complete message to the
macro base station 100. In addition, the communication control unit 157 notifies
I
I the selected small base station 200 of the fact that the terminal devices 300 use the
CC used by the selected small base station 200 as an SCC. As a result, the terminal
devices 300 perform radio communication with the selected small base station 200
30 using the SCC. A specific example of such carrier aggregation will be described
below with reference to FIG. 4.
[0069]
FIG. 4 is an illustrative diagram for describing the example of carrier
aggregation according to the present embodiment. Referring to FIG. 4, the macro
base station 100, the small base station 200, and the terminal device 300 are shown.
The small base station 200 is a small base station selected based on a measurement
result. The terminal device 300 performs radio communication with the macro base
station 100 using a CC for the macrocell 10 as a PCC, and performs radio
communication with the small base station 200 using a CC for the small cell 20 as an
SCC.
[0070]
With such carrier aggregation, the terminal device 300 can perform radio
communication with the small base station 200 that has been activated as necessary
while continuing radio communication with the macro base station 100. Since there
is no chance of handover of the PCC as long as the terminal device 300 is positioned
with the macrocell 10, for example, a load of signaling for the terminal device 300
can be lightened. In addition, a communication speed of the terminal device 300,
for example, can be enhanced. In addition, since measurement with regard to the
small cell 20 is necessary for this carrier aggregation, the above-described procedure
of measurement is particularly useful.
[0071]
Note that the process for adding an SCC may include transnrission of a
media access control (MAC) control element to the terminal device 300, instead of
transmission of the RRC connection reconfiguration message to the terminal device
300.
100721
<<3. Configuration of a small base station>>
An example of a configuration of the small base station 200 according to the
present embodiment will be described with reference to FIG. 5. FIG. 5 is a block
diagram showing the example of the configuration of the small base station 200
according to the present embodiment. Referring to FIG. 5, the small base station
200 includes an antenna unit 210, a radio communication unit 220, a network
communication unit 230, a storage unit 240, and a processing unit 250.
[0073]
(Antenna unit 2 10)
The antenna unit 210 receives radio signals and outputs the received radio
5 signal to the radio communication unit 220. In addition, the antenna unit 210
transmits transmission signals output by the radio communication unit 220.
[0074]
(Radio communication unit 220)
The radio communication unit 220 performs radio communication with the
10 terminal device 300 positioned within the small cell 20. For example, the radio
communication unit 120 perfonns radio communication with the terminal device 300
using a frequency band for the small cell 20. The frequency band includes, for
example, one or more CCs.
[0075]
15 Particularly in the present embodiment, the radio communication unit 220
stops radio communication when the small base station 200 is in the idle state. For
example, the station stops both transmission in the downlink and reception in the
uplink.
[0076]
20 (Network communication unit 230)
The network communication unit 230 communicates with other
communication nodes. For example, the network communication unit 230
communicates with the macro base station 100. In addition, the network
communication unit 130 communicates with, for example, other small base stations ~ 25 200. In addition, the network communication unit 230 communicates with, for
I
I
I example, core network nodes.
I [0077]
(Storage unit 240)
The storage unit 240 stores programs and data for operations of the small
I 30 base station 200.
[0078]
(Processing unit 250)
The processing unit 250 provides various functions of the small base station
200. The processing unit 250 includes a state control unit 251 and the
communication control unit 252.
[0079]
(State control unit 251)
The state control unit 25 1 controls the small base station 200 such that the
small base station 200 is in the idle state. For example, the state control unit 251
causes the radio communication unit 220 to stop transmission in the downlink andlor
reception in the uplink. In addition, the state control unit 251 causes the
communication control unit 252 to stop control over transmission in the downlink
andlor control over reception in the uplink.
[0080]
In addition, the state control unit 251 controls the small base station 200
such that the small base station 200 is in the state in which the station can
communicate with the terminal device 300. That is, the state control unit 251
activates the small base station 200. For example, the state control unit 251 causes
the radio communication unit 220 to resume transmission in the downlink and/or
reception in the uplink. In addition, the state control unit 251, for example, causes
the communication control unit 252 to resume control over transmission in the
downlink and/or control over reception in the uplink. Note that, as an initial state,
for example, transmission in the downlink and/or reception in the uplink are stopped.
In addition, as the initial state, control over transmission in the downlink and/or
control over reception in the uplink are stopped.
[0081]
In addition, the state control unit 251 controls the small base station 200
such that the small base station 200 is in the idle state or the small base station 200 is
in the state in which the station can communicate with the terminal device 300
according to control of the macro base station 100. As an example, when the macro
base station 100 transmits an activation instruction message for instructing activation
to the small base station 200, the state control unit 25 1 controls the small base station
200 such that the small base station 200 in the state in which the station can
communicate with the terminal device 300. In addition, as another example, when
the macro base station 100 transmits to the small base station 200 an idling
instruction message instructing it to be in the idle state, the state control unit 251
5 controls the small base station 200 such that the small base station 200 is in the idle
state.
[0082]
Particularly in the present embodiment, when the small base station 200 is
selected as a small base station that will not be set in the idle state based on a result
10 of measurement (i.e., measurement result) by the terminal device 300 with regard to
the one or more small cells 20, the transmission control unit 251 does not cause the
small base station 200 to be in the idle state. For example, the small base station
200 is selected as a small base station that will not be set in the idle state based on the
measurement result. In addition, the small base station 200, for example, has
15 already been activated for transmission of a measurement signal. In this case, the
macro base station 100 does not transmit the idling instruction message to the small
base station 200. For this reason, the transmission control unit 251 controls the
small base station 200 such that the small base station 200 is not in the idle state.
[0083]
20 Note that, as described above, the small base station 200 may resume only
transmission in the downlink for transmission of the measurement signal and may
not resume reception in the uplink. In this case, the macro base station 100
transmits the activation instruction message to the small base station 200. For this
reason, the transmission control unit 25 1 controls the small base station 200 such that
25 the small base station 200 is in the state in which the station can communicate with
the terminal device 300.
[0084]
In addition, the small base station 200 of the small cell 20 may be activated
first at the time of transmission of the measurement signal and return to the idle state
30 again after the transmission of the measurement signal. In this case, the macro base
station 100 transmits the activation instruction message to the small base station 200.
i
! For this reason, the transmission control unit 251 controls the small base station 200
I
I such that the small base station 200 is in the state in which the station can
communicate with the terminal device 300.
I
[00S5]
i
5 (Communication control unit 252)
The communication control unit 252 controls radio communication in the
small cell 20.
[0086]
For example, the communication control unit 252 controls transmission in
10 the downlink and rcccption in the downlink by the small base station 200.
[0087]
Particularly in the present embodiment, the communication control unit 252
controls transmission of a signal for measurement (i.e., measurement signal) by the
terminal device 300 with regard to the small cell 20. For example, the
con~municationc ontrol unit 252 controls transmission of a downlink signal including
the measurement signal. As described above, the downlink signal is, for example, a
reference signal. In addition, the small base station 100, for example, may stop
transmission in the downlink and control of the transmission as the initial statc;
however, when the macro base station 100 transmits the activation instruction
message for the measurement, the small base station 100 resumes transmission in the
downlink and control of the transmission. Thus, the communication control unit
252 controls transmission of the downlink signal including the measurement signal.
[OOSS]
Furthermore, particularly in the present embodiment, when the small base
station 200 is selected as a small base station that will not be set in the idle state
based on the measurement result, for example, the communication control unit 252
controls the terminal device 300 to use a frequency band for the small cell 20 as one
of one or more auxiliary frequency bands.
[0089]
To be more specific, for example, the macro base station 100 notifies the
small base station 200 of the fact that the terminal device 300 is set to use a CC for
the small cell 20 (i.e., a CC used by the small base station 200) as an SCC. Then,
the communication control unit 157 controls the termir~ald evice 300 to usc the CC
for the small cell 20 as an SCC. As an example, the communication control unit
157 allocates radio resources of the CC of the small cell 20 to the terminal device
300. In addition, as another example, the terminal device 300 is provided with
control information regarding the CC of the small cell 20.
[0090]
<<4. Configuration of a terminal device>>
An example of a configuration of the terminal device 300 according to the
present embodiment will be described with reference to FIG. 6. FIG. 6 is a block
diagram showing the exanlple of the configuration of the terminal device 300
according to the present embodiment. Referring to FIG. 6, the terminal device 300
includes an antenna unit 310, a radio communication unit 320, a storage unit 330, an
input unit 340, a display unit 350, and a processing unit 360.
[0091]
(Antenna unit 3 10)
The antenna unit 310 receives radio signals and outputs the received radio
signals to the radio communication unit 320. In addition, the antenna unit 310
transmits transmission signals output by the radio communication unit 320.
[0092]
(Radio communication unit 320)
The radio communication unit 320 performs radio communication with the
macro base station 100 when the terminal device 300 is positioned within the
macrocell 10. For example, the radio communication unit 320 performs radio
communication with the macro base station 100 using the frequency band for the
macrocell 10 (for example, one or more CCs).
[0093]
In addition, the radio communication unit 320 performs radio
communication with the small base station 200 when the terminal device 300 is
positioned within the small cell 20. For example, the radio communication unit 320
performs radio communication with the small base station 200 using the frequency
band for the small cell 20 (for example, one or more CCs).
[0094]
(Storage unit 330)
The storage unit 330 stores programs and data for operations of the terminal
device 300.
[0095]
(Input unit 340)
The input unit 340 receives inputs by a user of the terminal device 300.
Then, the input unit 340 provides the result of the inputs to the processing unit 360.
[0096]
(Display unit 350)
The display unit 350 displays output screens (i.e., output images) from the
terminal device 300. For example, the display unit 350 displays output screens
according to control by the processing unit 360 (a display control unit 367).
[0097]
(Processing unit 360)
The processing unit 360 provides various functions of the terminal device
300. The processing unit 360 includes a demand notification unit 361, a position
information providing unit 362, a measurement unit 363, a measurement result
acquisition unit 364, a measurement result providing unit 365, a communication
control unit 366, and u display control unit 367.
[0098]
(Demand notification unit 361)
The demand notification unit 361 notifies other devices of a demand of the
terminal device 300.
[00991
For example, the demand notification unit 361 notifies the macro base
station 100 or the small base station 200 of a demand of the terminal device 300
regarding radio communication. As an example, the demand notification unit 361
may notifi the macro base station 100 of a demand for performing radio
communication in the small cell 20.
[OlOO]
(Position information providing unit 362)
The position information providing unit 362 provides position information
that indicates a position of the terminal device 300.
5 [OlOl]
For example, the position information providing unit 362 provides the
position information to the macro base station 100. To be more specific, for
example, the macro base station 100 transmits a position information requesting
message of requesting provision of the position information to the terminal device
10 300. Then, the position information providing unit 362 acquires the position
information and provides the information to the macro base station 100.
[O 1021
The position information is acquired through, for example, the Global
Positioning System (GPS). Alternatively, the position information may be acquired
1.5 through positioning by the terminal device 300 using a downlink signal from a
plurality of base stations. Alternatively, the position information may be acquired
through positioning by a plurality of base stations using an uplink signal from the
terminal device 300.
[0 1031
20 (Measurement unit 363)
The rneasurcment unit 363 performs measurement with regard Lo the small
cell 20.
[0 1041
For example, the measurement unit 363 performs measurement with regard
25 to one or more small cells 20 based on information regarding the one or more slnall
cells 20 (i.e., small cell information) provided from the macro base station 100. As
described above, the small cell information includes, for example, frequency channel
information and timing information. Then, the measurement unit 363 performs
measurement with a frequency channel indicated by the frequency channel
30 information at a timing indicated by the timing information.
~01051
In addition, the measurement is, for example, measurement of reception
power or quality of a measurement signal transmitted from the small base station 200
To be more specific, for example, the measurement signal is a reference signal
transmitted from the small base station 200 as described above, and the measurement
5 is measurement of RSRP or RSRQ.
[0106]
(Measurement result acquisition unit 364)
The measurement result acquisition unit 364 acquires the result of
measurement with regard to the small cells 20.
10 [0107]
Particularly in the present embodiment, the measurement result acquisition
unit 364 acquires the result of measurement (i.e., measurement result) with regard to
the one or more small cells 20. The content of the measurement result is as
described for the measurement result acquisition unit 155 of the macro base station
15 100.
[OlOS]
(Measurement result providing unit 365)
The measurement result providing unit 365 provides the result of
measurement with regard to the small cells 20.
20 [0109]
Particularly in the present embodiment, the measurement result providing
unit 365 provides the result of measurement (i.e., measurement result) with regard to
the one or more small cells 20 to the macro base station 100. The content and
providing technique of the measurement result are as described for the measurement
25 result acquisition unit 155 of the macro base station 100.
[OllO]
(Communication control unit 366)
The communication control unit 366 controls radio communication of the
terminal device 300.
30 [Olll]
Particularly in the present embodiment, for example, the coinmunication
control unit 366 controls radio communication of the terminal device 300 such that
the terminal device uses a frequency band for the macrocell 10 as one principal
frequency band and uses a frequency band for the small cells 20 as one of one or
more auxiliary frequency bands. To be more specific, for example, the
5 communication control unit 366 performs a setting with regard to radio
communication on the terminal device 300 such that the terminal device uses a CC
for the macrocell 10 as a PCC and uses a CC for the small cells 20 as an SCC.
[0112]
As an example, the terminal device 300 is assumed to perform radio
10 communication with the rnacro base station 100 using the CC for the macrocell 10 as
a PCC. Then, the macro base station 100 notifies the terminal device 300 of an
RRC connection reconfiguration message for adding a CC used by a selected small
base station 200 as an SCC. Then, the communication control unit 366 adds the CC
as an SCC. In addition, the communication control unit 366 transmits an RRC
15 connection reconfiguration complete message to the base station 100 via the radio
communication unit 320.
[0113]
(Display control unit 367)
The display control unit 367 controls display of an output screen by the
20 display unit 350. For example, the display control unit 367 generates an output
screen to be displaycd by the display unit 350, and causes the display unit 350 to
display the output screen
[0114]
<<5. Process flow>>
i
I 25 Next, an example of a communication control process according to the
I
I
present embodiment will be described with reference to FIGS. 7 and 8.
!
I
,I [0115]
(First example)
FIG. 7 is a flowchart showing a first example of a schematic flow of the
30 communication control process according to the present embodiment.
[0116]
First, the macro base station 100 transmits a position information request
message that requests provision of position information that indicates a position of
the terminal device 300 to the terminal device 300 (S401). Then, the terminal
device 300 acquires the position information and provides the information to the
5 macro base station 100 (S403).
[0117]
Next, the macro base station 100 selects one or more small cells 20 present
in the vicinity of the position of the terminal device 300 indicated by the position
information from small cells 20 (S405).
10 [0118]
Then, the macro base station 100 provides information regarding the one or
more small cells 20 (small cell information) to the terminal device 300 (S407).
[0119]
In addition, the macro base station 100 transmits an activation instruction
15 message to small base stations 200 of the one or more small cells 20 (S409). Then,
the small base stations 200 are activated (S411), and resume transmission of
downlink signals including reference signals (S413).
[0120]
On the other hand, the terminal device 300 performs measurement with
20 regard to the one or more small cells 20 based on the small cell information (S415).
Then, the terminal device 300 provides the result of the measurement (i.e.,
measurement result) with regard to the one or more small cells 20 to the macro base
:: : station 100 (S417).
ii ;
,: [0121]
.j
i 25 Then, the macro base station 100 selects a small base station 200 that will
i/
!i not be set in the idle state from the small base stations 200 of the one or more small
$
I cells 20 based on the measurement result (S419). Here, the small base station 200
Ii
shown in FIG. 7 is set to be selected. Note that the macro base station 100 transmits
an idling instruction message for instructing the small base stations 200 other than
30 the selected small base station 200 (i.e., other small base stations 200) from the one
or more small base stations 200 to be in the idle state. Then, the other small base
stations 200 go into the idle state.
[O 1221
Then, the macro base station 100 transmits the RRC connection
reconfiguration message for adding a CC to be used by the selected small base
5 station 200 as an SCC to the terminal device 300 (S421). Then, the terminal device
300 adds the CC used by the selected small base station 200 (CC for the
corresponding small cell 20) as an SCC (S423), and transmits the RRC connection
reconfiguration complete message to the macro base station 100 (S425).
[0123]
10 In addition, the macro base station 100 notifies the selected small base
station 200 of the fact that the CC used by the selected small base station 200 will be
used as the SCC by the terminal device 300 (S427). Then, the terminal device 300
performs radio communication with the selected small base station 200 using the CC
for the small cell 20 as the SCC while performing radio communication with the
15 macro base station 100 using the CC for the macrocell 10 as the PCC.
[0 1241
(Second example)
FIG. 8 is a flowchart showing a second example of a schematic flow of the
communication control process according to the present embodiment.
20 [0125]
In the second example, the terminal device 300 transmits a refr~cnces ignal
in the uplink (S431). Then, the macro base station 100 acquires the position
information through positioning of the terminal device 300 using the reference signal
:I (S433).
! 25 [0126]
:!
I
I Note that the following Steps S405 to S427 are the same as described in the
I
1 first example with reference to FIG. 7.
1
I [0 1271
I
I
I <<6. Modified examples>>
30 Next, a first modified example and a second modified example relating to
the present embodiment will be described.
[0128]
(First modified example)
In the above-described embodiment, the small base stations 200 stop both
transmission in the downlink and reception in the uplink when the stations are in the
5 idle state. Embodiments, however, are not limited thereto. In the first modified
example of the embodiment, the small base stations 200 stop transmission in the
downlink and do not stop reception in the uplink when the stations are in the idle
state.
101291
10 Note that, in the first modified example, for example, the same processes as
the communication control processes described with reference to FIGS. 7 and 8 arc
performed.
[0130]
(Second modified example)
15 On the other hand, in the second modified example of the embodiment, the
small base stations 200 stop reception in the uplink and do not stop transmission in
the downlink when they are in the idle state.
[0131]
In the second modified example, the small base stations 200 transmit
20 measurement signals (reference signals) in the downlink even when there is no
control from the macro base station 100. Thus, for example, some or all of Steps
S401 to S413 can be omitted from the communication control process described with
reference to FIG. 7.
[0132]
25 (Third modified example)
In the example of the above-described embodiment, the small base stations
I
I 200 slop communication (transmission in the downlink andlor reception in the
uplink) when the stations are in the idle state. Embodiments, however, are not
I limited thereto. In a third modified example of the embodiment, the small base
30 stations 200 perform radio communication while reducing power consumption,
rather than completely stopping radio communication when the stations are in the
idle state. For example, the small base stations 200 perform discontinuous
transmission (DTX) in the downlink and/or discontinuous reception (DRX) in the
uplink when the stations are in the idle state.
[0133]
5 <<7. Application examples>>
The technology of the present disclosure can be applied to various products.
For example, the macro base station 100 may be realizcd as any type of Evolved
Node B (eNB) such as a macro eNB (MeNB) or a master eNB (MeB). In addition,
the small base station 200 may be realized as any type of eNB such as a pico eNB
10 (PeNB), a home eNB (HeNB), or a secondary eNB (SeB). Instead, the macro base
station 100 and the small base station 200 may be realized as other types of base
stations such as a NodeB or a base transceiver station (BTS). The macro base
station 100 and the small base station 200 may each include a main body which
controls radio communication (which is also referred to as a base station devicc) and
I 15 one or more remote radio heads (RRHs) disposed in a different location from the
main body.
[0134]
In addition, for example, the terminal device 300 may be realized as a
mobile terminal such as a smartphone, a tablet personal computer (PC), a notebook
20 PC, a portable game terminal, or a digital camera, or an in-vehicle terminal such as a
car navigation devicc. In addition, the terminal device 300 may be rcalized as a
I; terminal which performs machine-to-machine (M2M) communication (which is also
;!
;I!I
referred to as a machine-type communication (MTC) terminal). Furthermore, the
::
terminal device 300 may be a radio communication module mounted in such a
j/
I 25 terminal (for example, an integrated circuit module configured in one die).
:,j: [0135]
:I
17-1. Application examples of a base station>
I
I (First application example)
FIG. 9 is a block diagram showing a first example of a schematic
30 configuration of an eNB to which the technology according to the present disclosure
may be applied. An eNB 800 includes one or more antennas 810, and a base station
device 820. The respective antennas 810 and the base station device 820 may be
connected to each other via an RF cable.
[0136]
Each antenna 810 includes a single or a plurality of antenna elements (for
example, a plurality of antenna elements constituting a MlMO antenna), and is used
by the base station device 820 to transmit and receive radio signals. The eNB 800
may include a plurality of antennas 810 as shown in FIG. 9, and the plurality of
antennas 810 may respectively correspond to a plurality of frequency bands used by
the eNB 800, for example. Note that, although FIG. 9 illustrates an example of the
eNB 800 including a plurality of antennas 810, the eNB 800 may also include a
single antenna 8 10.
[0137]
The base station device 820 is equipped with a controller 821, a memory
822, a network interface 823, and a radio communication interface 825.
[0138]
The controller 821 may be a CPU or DSP, for example, and causes various
higher-layer functions of the base station device 820 to operate. For example, the
controller 821 generates a data packet from data inside a signal processed by the
radio communication interface 825, and forwards the generated packet via the
network interface 823. The controller 821 may also generate a bundled packet by
bundling data from a plurality of baseband processors, and forward tl~cg enerated
bundled packet. The memory 822 includes a RAM and a ROM, and stores
programs executed by the controller 821 as vie11 as various control data (such as a
terminal list, transmit power data, and scheduling data, for example).
[0139]
The network interface 823 is a communication interface for connecting the
base station device 820 to a core network 824. The network interface 823 may also
be a wired communication interface, or a wireless communication interface for
wireless backhaul. In the case in which the network interface 823 is a wireless
communication interface, the network interface 823 may use a higher frequency band
for wireless communication than the frequency band used by the radio
communication interface 825.
[0140]
The radio communication interface 825 supports a cellular communication
scheme such as Long Term Evolution (LTE) or LTE-Advanced, and provides a radio
5 connection to a terminal positioned inside the cell of the eNB 800 via an antenna 810.
Typically, the radio communication interface 825 may include a baseband (BB)
processor 826, an RF circuit 827, and the like. The BB processor 826 may conduct
processes such as encodingldecoding, modulation/demodulation, and
multiplexingldemultiplexing, for example, and executes various signal processing in
10 a layer 1, a layer 2 (fol example, Medium Access Control (MAC), Radio Link
Control (RLC), and Packet Data Convergence Protocol (PDCP), and a layer 3 (for
example, Radio Resource Control (RRC)). The BB processor 826 may be a module
including a memory that stores a communication control program, a processor that
executes such a program, and related circuits. The functions of the BB processor
15 826 may also he modifiable by updating the program. Also, the module may he a
card or a blade inserted into a slot of the base station device 820, or a chip mounted
onboard the card or the blade. Meanwhile, the RF circuit 827 may include
components such as a mixer, a filter, and an amp, and transmits or receives a radio
signal via an antenna 810.
[0141]
The radio communication interface 825 may also include a plu~.ality of BB
processors 826 as shown in FIG. 9, and the plurality of BB processors 826 may
respectively correspond to a plurality of frequency bauds used by the eNB 800, for
example. I11 addition, the radio communication interface 825 may also include a
plurality of RF circuits 827 as shown in FIG. 9, and the plurality of RF circuits 827
may respectively correspond to a plurality of antenna elements, for example. Note
that although FIG. 9 illustrates an example of the radio communication interface 825
including a plurality of BB processors 826 and a plurality of RF circuits 827, the
radio communication interface 825 may also include a single BB processor 826 or a
single RF circuit 827.
[01421
(Second application example)
FIG. 10 is a block diagram showing a second example of a schematic
configuration of an eNB to which the technology according to the present disclosure
may be applied. An eNB 830 includes one or more antennas 840, a base station
device 850, and an RRH 860. The respective antennas 840 and the RRH 860 may
be connected to each other via an RF cable. Also, the base station device 850 and
the RRH 860 may be connected to each other by a high-speed link such as an optical
fiber cable.
[0143]
Each antenna 840 includes a single or a plurality of antenna elements (for
example, a plurality of antenna elements constituting a MIMO antenna), and is used
by the RRH 860 to transmit and receive radio signals. The eNB 830 may include a
plurality of antennas 840 as shown in FIG. 10, and the plurality of antennas 840 may
respectively correspond lo a plurality of frequency bands used by the eNB 830, for
example. Note that although FIG. 10 illustrates an examplc of the eNB 830
including a plurality of antennas 840, the eNB 830 may also include a single antenna
840.
[0 1441
The base station device 850 is equipped with a controller 851, a memory
852, a network interface 853, a radio communication interface 855, and a connection
interface 857. The controller 851, the memory 852, and the network it~lcrface8 53
are similar to the controller 821, the memory 822, and the network interface 823
described with reference to FIG. 9.
[0145]
The radio communication interface 855 supports a cellular communication
scheme such as LTE or LTE-Advanced, and provides a radio connection to a terminal
positioned inside a sector corresponding to the RRH 860 via the RRH 860 and an
antenna 840. Typically, the radio communication interface 855 may include a BB
processor 856 and the like. The BB processor 856 is similar to thc BB processor
826 described with reference to FIG 9, except for being connected to an RF circuit
864 of the RRH 860 via the connection interface 857. The radio communication
interface 855 may also include a plurality of BB processors 856 as shown in FIG. 10,
and the plurality of BB processors 856 may respectively correspond to a plurality of
frequency bands used by the eNB 830, for example. Note that although FIG. 10
illustrates an example of the radio communicatioil interface 855 including a plurality
of BB proccssors 856, the radio communication interface 855 may also include a
single BB processor 856.
[O 1461
The connection interface 857 is an interface for connecting the hase station
device 850 (radio communication interface 855) to the RRH 860. The connection
interface 857 may also be a communication module for communication on the highspeed
link connecting the hase station device 850 (radio communication interface
855) and the RRH 860.
[0147]
In addition, the RRH 860 is equipped with a connection interface 861 and a
radio communication interface 863.
[0148]
The connection interface 861 is an interface for connecting the RRH 860
(radio communication interface 863) to the base station device 850. The connection
interface 861 may also be a communication module for communication on the highspeed
link.
[O 1491
The radio communication interface 863 transmits and receives a radio signal
via an antenna 840. Typically, the radio communication interface 863 may include
an RF circuit 864. The RF circuit 864 may include components such as a mixer, a
filter, and an amp, and transmits or receives a radio signal via an antenna 840. The
radio communication interface 863 may also include a plurality of RF circuits 864 as
shown in FIG. 10, and the plurality of RF circuits 864 may respectively correspond to
a plurality of antenna elements, for example. Note that although FIG. 10 shows an
example of the radio communication interface 863 including a plurality of RE'
circuits 864, the radio communication interface 863 may also include a single RF
circuit 864.
[0150]
In the eNB 800 and the eNB 830 shown in FIGS. 9 and 10, the processing
unit 150 of the macro base station 100 described using FIG. 2 (or each constituent
element included in the processing unit 150) and the processing unit 250 of the small i 1 5 base station 200 described using FIG. 5 (or each constituent element included in the
'!
I processing unit 250) may be implemented in the radio communication interface 825,
and the radio communication interface 855 and/or the radio communication interface
863. Also, at least some of these functions may also be implemented in the
controller 821 and the controller 851.
10 [0151]
17-2. Application examples of a terminal device>>
(First application example)
FIG. 11 is a block diagram showing an example of a schematic configuration
of a smartphone 900 to which the technology according to the present disclosure may
15 be applied. The smartphone 900 is equipped with a processor 901, a memory 902,
storage 903, an external connection interface 904, a camera 906, a sensor 907, a
microphone 908, an input device 909, a display device 910, a speaker 911, a radio
communication interface 912, one or more antenna switches 915, one or more
antennas 916, a bus 917, a battery 918, and an auxiliary controller 919.
20 [0152]
The processor 901 may be a CPU or system-on-a-chip (SoC), tor example,
and controls functions in the application layer and other layers of the smartphone 900.
:;
The memory 902 includes RAM and ROM, and stores programs executed ~ by the
I processor 901 as well as data. The storage 903 may include a storage medium such 1 25 as a semiconductor memory or a hard disk. The external connection interface 904 : is an interface for connecting an externally attached device, such as a memory card
or Universal Serial Bus (USB) device, to the smartphone 900.
I !
[0153]
I
I The camera 906 includes an image sensor such as a charge-coupled device
!
I
i1 30 (CCD) or complementary metal-oxide-semiconductor (CMOS) sensor, and generates
1 a captured image. The sensor 907 may include a sensor group such as a positioning
sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor, for exan~ple.
The microphone 908 converts audio input into the smartphone 900 into an audio
signal. The input device 909 includes devices such as a touch sensor that detects
touches on a screen of the display device 910, a keypad, a keyboard, buttons, or
5 switches, and receives operations or information input from a user. The display
device 910 includes a screen such as a liquid crystal display (LCD) or an organic
light-emitting diode (OLED) display, and displays an output image of the
smartphone 900. The speaker 911 converts an audio signal output from the
smartphone 900 into audio.
10 [0154]
The radio communication interface 912 supports a cellular communication
scheme such as LTE or LTE-Advanced, and executes radio communication.
Typically, the radio communication interface 912 may include a BB processor 913,
an FW circuit 914, and the like. The BB processor 913 may conduct processes such
15 as encoding/decoding, modulationldemodnlation, and multiplcxingldemultiplexing,
for example, and executes various signal processing for radio communication.
Meanwhile, the RF circuit 914 may include components such as a mixer, a filter, and
an amp, and transmits or receives a radio signal via an antenna 916. The radio
communication interface 912 may also be a one-chip module integrating the BB
20 processor 913 and the RF circuit 914. The radio communication interface 912 may
also include a plurality of BB processors 913 and a plurality of RF cilcuits 914 as
illustrated in FIG. 11. Note that although FIG. 11 illustrates an example of the radio
communication interface 912 including a plurality of BB processors 913 and a
plurality of RF circuits 914, the radio communication interface 912 may also include
t 25 a single BB processor 91 3 or a single RF circuit 914.
I
I
j
[OlSS]
Furthermore, in addition to a cellular communication scheme, the radio
communication interface 912 may also support other types of radio communication
schemes such as a short-range wireless communication scheme, a near field wireless
30 communication scheme, or a wireless local area network (LAN) scheme. In this
case, a BB processor 913 and an RF circuit 914 may be included for each radio
communication scheme.
[0156]
Each antenna switch 91 5 switches the destination of an antenna 91 6 among
a plurality of circuits included in the radio communication interface 912 (for example,
5 circuits for different radio communication schemes).
[0157]
Each antenna 916 includes a single or a plurality of antenna elements (for
example, a plurality of antenna elements constituting a MlMO antenna), and is used
by the radio communication interface 912 to transmit and receive radio signals.
10 The smartphone 900 may also include a plurality of antennas 916 as shown in FIG.
11. Note that although FIG. 11 illustrates an example of the smartphone 900
,! including a plurality of antennas 916, the smartphone 900 may also include a single
'I 'I antenna 91 6.
[0158]
15 Furthermore, the smartphone 900 may also be equipped with an antenna 916
:: for each radio communication scheme. In this case, the antenna switch 915 may be
omitted from the configuration of the smartphone 900.
[01591
I The bus 917 interconnects the processor 901, the memory 902, the storage
20 903, the external connection interface 904, the camera 906, the sensor 907, the
microphone 908, thc input device 909, the display device 910, the spealtcr 911, the
i' radio communication interface 912, and the auxiliary controller 919. The battery
!I
!I 9 18 supplies electric power to the respective blocks of the smartphone 900 shown in
'1
FIG. 11 via power supply lines partially illustrated with dashed lines in the drawing.
:I
25 The auxiliary controller 919 causes the smartphone 900 to operate minimal necessary
functions, for example, in a sleep mode.
I
I
[0160]
I ~ In the smartphone 900 shown in FIG. 11, the processing unit 360 of the
I terminal device 300 described using FIG. 6 (or each constituent element included in
30 the processing unit 360) may be implemented in the radio communication interface
912. Also, at least some of these functions may also be implemented in the
processor 901 or the auxiliary controller 919.
[0161]
(Second application example)
FIG. 12 is a block diagram illustrating an example of a schematic
configuration of a car navigation device 920 to which technology according to an
embodiment of the present disclosure may he applied. The car navigation device
920 is equipped with a processor 921, a memory 922, a Global Positioning System
(GPS) module 924, a sensor 925, a data interface 926, a content player 927, a storage
medium interface 928, an input device 929, a display device 930, a speaker 931, a
radio communication interface 933, one or more antenna switches 936, one or more
antennas 937, and a battery 938.
[0162]
The processor 921 may be a CPU or SoC, for example, and controls a car
navigation function and other functions of the car navigation device 920. The
memory 922 includes RAM and ROM, and stores programs executed by the
processor 921 as well as data.
101631
The GPS module 924 measures the position of the car navigation device 920
(for example, the latitude, longitude, and altitude) by using GPS signals received
from GPS satellites. The sensor 925 may include a sensor group such as a gyro
sensor, a geomagnetic sensor, and a barometric pressure sensor, for exanlple. The
data interface 926 is connected to an in-vehicle network 941 via a port not illustrated
in the drawing, and acquires data generated on the vehicle side, such as vehicle speed
data.
101641
The content player 927 plays content stored on a storage medium (for
example, a CD or DVD) inserted into the storage medium interface 928. The input
device 929 includes devices such as a touch sensor that detects touches on a screen of
the display device 930, buttons, or switches, and receives operations or information
input from a user. The display device 930 includes a screen such as an LCD or
OLED display, and displays a navigation function or an image of played-back
content. The speaker 931 outputs audio of a navigation function or played-back
content.
[0165]
The radio communication interface 933 supports a cellular communication
5 scheme such as LTE or LTE-Advanced, and executes radio communication.
Typically, the radio communication interface 933 may include a BB processor 934,
an RF circuit 935, and the like. The BB processor 934 may conduct processes such
as encodingldecoding, modulatioddemodulation, and multiplexingldemultiplexing,
for example, and executes various signal processing for radio communication.
10 Meanwhile, the RF circuit 935 may include components such as a mixer, it filter, and
an amp, and transmits or receives a radio signal via an antenna 937. The radio
communication interface 933 may also be a one-chip module integrating the BB
processor 934 and the RF circuit 935. The radio communication interface 933 may
also include a plurality of BB processors 934 and a plurality of RE circuits 935 as
15 shown in FIG. 12. Note that although FIG. 12 illustrates an example of the radio
communication interface 933 including a plurality of BB processors 934 and a
plurality of RF circuits 935, the radio communication interface 933 may also include
a single BB processor 934 or a single RF circuit 935.
[0 1661
20 Furthermore, in addition to a cellular communication scheme, the radio
communication interface 933 may also support other types of radio con~tnunication
schemes such as a short-range wireless communication scheme, a near field wireless
communication scheme, or a wireless LAN scheme. In this case, a BB processor
934 and an RF circuit 935 may be included for each radio communication scheme.
25 [0167]
Each antenna switch 936 switches the destination of an antenna 937 among
! a plurality of circuits included in the radio communication interface 933 (for example; ~ circuits for different radio communication schemes).
I [0168]
! 30 Each antenna 937 includes a single or a plurality of antenna elements (for
example, a plurality of antenna elements constituting a MIMO antenna), and is used
by the radio communication interface 933 to transmit and receive radio signals.
The car navigation device 920 may also include a plurality of antennas 937 as shown
in FIG. 12. Note that although FIG. 12 illustrates an example of the car navigation
device 920 including a plurality of antennas 937, the car navigation devicc 920 may
5 also include a single antenna 937.
[0169]
Furthermore, the car navigation devicc 920 may also be equipped with an
antenna 937 for each radio communication scheme. In this case, the antenna switch
936 may be omitted from the configuration of the car navigation device 920.
10 [0170]
The battery 938 supplies electric power to the respective blocks of the car
navigation device 920 shown in FIG. 12 via power supply lines partially illustrated
with dashed lines in the drawing. Also, the battery 938 stores electric power
supplied from the vehicle.
15 [0171]
In the car navigation device 920 shown in FIG. 12, the processing unit 360
of the terminal device 300 described using FIG. 6 (or each constituent element
included in the processing unit 360) may be implemented in the radio
communication interface 933. Also, at least some of these litnctions may also be
20 implemented in the processor 921.
[0172]
In addition, the technology according to the present disclosure may also be
realized as an in-vehicle system (or vehicle) 940 that includes one or more blocks of
the car navigation device 920 discussed above, the in-vehicle network 941, and a
25 vehicle-side module 942. The vehicle-side module 942 generates vehicle-side data
such as the vehicle speed, number of engine revolutions, or malfunction information,
and outputs the generated data to the in-vehicle network 941.
[0 1731
<<8. Conclusion>>
30 So far, the respective nodes and processes according to cmbodiments of the
present disclosure have been described using FIGS. 1 to 8. According to
embodiments of the present disclosure, the measurement result acquisition unit 155
acquires the result of measurement (i.e., measurement result) performed by the
terminal device 300 with respect to one or more small cells 20. In addition, the
second selection unit 156 selects the small base station 200 that will not be set in the
5 idle state from small base stations 200 of thc one or more small cells 20 based on the
measurement result.
[O 1741
Accordingly, for example, a small base station 200 that is closer to the
terminal device 300 is not necessarily selected, and a small base station 200 that
10 brings more satisractory communication quality is selected as a small base station
200 that will not be set in the idle state. For this reason, while power consumption
of the small base stations 200 is reduced, degradation of communication quality of
radio communication in a small cell 20 can be suppressed.
[O 1751
15 In addition, for example, the first selection unit 152 selects the one or more
small cells 20 based on the position information that indicates a position of the
terminal device 300.
[O 1761
Accordingly, for example, a small base station 200 having a possibility of
20 performing radio communication with the terminal device 300 is selected, and a
small base station 200 having no possibility of performing radio commul~icationw ith
the terminal device 300 is not selected. As a result, power consumption can be
further reduced.
[0177]
25 In addition, for example, the small cell control unit 154 does not cause the
I selected small base station 200 to be in the idle state and causes a small base station
I
I 200 other than the selected small base station 200 among small base stations 200 of
i
the one or more small cells 20 to be in the idle state.
[0178]
30 Accordingly, the terminal device 300 can perform radio communication in
the small cells 20 and power consumption of the small base stations 200 can be
reduced.
[O 1791
In addition, for example, the small cell control unit 154 causes the small
base stations 200 of the onc or more small cells 20 to transmit a signal for
5 measurement.
[01 801
Accordingly, even in the state in which the small hase stations 200 are in the
idle state and transmission in the downlink is not performed, measurement with
regard to the one or more small cells 20 can be thereafter performed.
10 [OlSl]
In addition, for example, the transmission control unit 152 provides
information regarding the one or more small cells 20 (i.e., small cell information) to
the terminal device 300.
[0182]
15 Accordingly, a load of measurement on the terminal device 300 can be
lightened.
[0183]
In addition, for example, the small cell information includes information
that indicates a frequency channel on which the signal for measurement is
20 transmitted by each of the small hase stations 200 of the one or more small cells 20
(i.e., frequency chan~reiln formation).
[O 1841
Accordingly, for example, the terminal device 300 can receive the signal for
measurement without searching for a frequency channel on which the signal for
25 measurement is transmitted. For this reason, a load of measurement on the terminal
device 300 can be lightened.
[0185]
In addition, for example, the small cell information includes information
that indicates timings at which the signal for measurement is transmitted by each of
30 the small hase stations 200 of the one or more small cells 20 (which is referred to as
"timing information").
[0186]
Accordingly, for example, the terminal device 300 can start reception of a
signal at the timing at which the signal for measurement is transmitted. That is, it is
not necessary for the terminal device 300 to continuously receive the signal over a
5 long period of time. For this reason, a load of measurement on the terminal device
300 can be lightened.
[0187]
In addition, for example, the communication control unit 157 controls the
terminal device 300 such that the terminal device uses the frequency band for the
10 macrocell 10 as one principal frequency band and uses the frequency band for the
small cell 20 of the selected small base station 200 as one of one or more auxiliary
frequency bands.
[0188]
With such carrier aggregation, the terminal device 300 can also perform
15 radio communication with a small base station 200 that is activated when necessary
while continuing radio communication with the macro base station 100. For
example, as long as the terminal device 300 is positioned within the macrocell 10,
there is no chance of handover of a PCC, and thus a load of signaling for the terminal
device 300 can be lightened. In addition, for example, a communication speed of
20 the terminal device 300 can be enhanced. Furthermore, since measurement with
regard to the small cclls 20 is necessary for such carrier aggregation, the procedure of
measurement described above is particularly effective.
[0189]
Although preferred embodiments of the present disclosure are described in
25 detail with reference to the accompanying drawings, the technical scope of the
present disclosure is not limited thereto. It should be understood by those slcilled in
the art that various modifications, combinations, sub-combinations and alterations
may occur depending on design requirements and other factors insofar as they are
I
I
within the scope of the appended claims or the equivalents thereof.
I ~ 30 [0190]
Although the example in which the communication system conforms to LTE
or LTE-A has been described, the present disclosure is not limited to the related
examples. For example, the communication system may be a system that conforms
to a different communication standard.
[0191]
Also, the processing steps in the communication processes in this
specification are not strictly limited to being executed in a time series following the
sequence described in the flowcharts. For example, the processing steps in the
communication processes may be executed in a sequence that differs from the
sequence described herein as flowcharts, and furthermore may be executed in
parallel.
[0 1921
In addition, a computer program for causing hardware such as a CPU, a
ROM, and a RAM installed in communication control devices (base station devices
of a macro base station and a small base stations) or a terminal device to exhibit the
same functions as the respective configurations of the aforementioned
communication control device or terminal device can also be created. In addition, a
storage medium for storing the computer program may also be provided. In
addition, an information processing device (for example, a processing circuit or a
chip) that includes a memory for storing the computer program (for example, a ROM
and a RAM) and a processor that executes the computer program (for example, a
CPU) may also be provided.
[0193]
In addition, the effects described in the present specification are merely
explanatory or illustrative, and not limitative. In other words, the technology
according to the present disclosure can exhibit, along with or instead of the effects,
other effects apparent to those slcilled in the art from the description of the present
specification.
10 1941
Additionally, the present technology may also be configured as below.
(1)
A comn~unicationc ontrol device including:
an acquisition unit configured to acquire a result of measurcmcnt performed
by a terminal device with regard to one or more small cells which are partly or
entirely overlapped by a macrocell; and
a selection unit configured to select a base station which is not to be set in
an idle state from base stations of the one or more small cells based on the result of
the measurement.
(2)
The communication control device according to (I), wherein the one or
more small cells are small cells selected based on position information which
indicates a position of the terminal device.
(3)
The communication control device according to (1) or (2), further including:
a control unit configured to control the base stations of the one or more
small cells,
wherein the control unit refrains from causing the selected base station to be
in the idle state, and causes a base station other than the selected base station among
the base stations of the one or more small cells to be in the idle state.
(4)
The communication control device according to (3), wherein the control unit
20 causes the base stations of the one or more small cells to transmit a signal for the
measurement.
(5)
The communication control device according to any one of (1) to (4), I
further including:
25 a providing unit configured to provide information regarding the one or
more small cells to the terminal device.
1
I
I (6)
The communication control device according to (5), wherein the
information regarding the one or more small cells includes information which
30 indicates a frequency channel on which a signal for the measurement is transmitted
by each of the base stations of the one or more small cells.
(7)
The communication control device according to (5) or (6), wherein the
information regarding the one or more small cells includes information which
indicates a timing at which a signal for the measurement is transmitted by each of the
base stations of the one or more small cells.
(8)
The communication control device according to (7), wherein the timing
depends on time taken for each of the base stations of the one or more small cells to
be activated from the idle state.
(9)
The communication control device according to (7) or (8), wherein the
signal for the measurement is a reference signal.
(10)
The communication control device according to any one of (1) to (9),
wherein the result of the measurement includes information regarding reception
power or quality of a signal for the measurement.
(11)
The communication control device according to any one of (1) to (lo),
wherein the result of the measurement is information regarding part of the one or
more small cells.
(12)
The communication control device according to any one of (1) to (ll),
wherein, when reception power or quality of a signal for the measurement with
regard to all of the one or more small cells does not exceed a predetermined
threshold value, the result of the measurement includes information which indicates
that the reception power or the quality with regard to all of the small cells does not
exceed the predetermined threshold value.
(13)
The terminal device according to any one of (1) to (12), wherein the
selection unit selects the base station that is not to be set in the idle state when
notification of a demand for performing radio communication in a small cell is given
by the terminal device.
(14)
The terminal device according to any one of (I ) to (l3),
wherein the terminal device is able to perform radio communication using
5 one principal frequency band and one or more auxiliary frequency bands, and
wherein the communication control device further includes a
communication control unit configured to control the terminal device to use a
frequency band for the macrocell as the one principal frequency band and to use a
frequcncy band for the small cell of the selected base station as one of the one or
10 more auxiliary frequency bands.
(15)
A communication control method including:
acquiring a result of measurement performed by a terminal device with
regard to one or more small cells which are partly or entirely overlapped by a
15 macrocell; and
selecting, using a processor, a base station which is not to be set in an idle
state from base stations of the one or more small cells based on the result of the
measurement.
(16)
20 A communication control device including:
a communication control unit configured to control transmission of a signal
for measurement performed by a terminal device with regard to a small cell which is
partly or entirely overlapped by a macrocell; and
a state control unit configured to refrain from causing a base station of the
25 small cell to be in an idle state when the base station of the small cell is selected as a
base station that is not to be set in the idle state based on a result of the measurement.
(17)
A terminal device including:
an acquisition unit configured to acquire a result of measurement with
30 regard to one or more small cells which are parlly or entirely overlapped by a
macrocell; and
a providing unit configured to provide the result of the measurement to a
communication control device which selects a base station which is not to be set in
an idle state from base stations of the one or more small cells based on the result of
the measurement.
5
Reference Signs List
[0 1951
1 communication system
10 macrocell
10 20 small cell
100 macro base station
15 1 position information acquisition unit
152 first selection unit
153 information providing unit
15 154 small cell control unit
155 measurement result acquisition unit
156 second selection unit
157 communication control unit
200 small base station
20 25 1 state control unit
253 communication control unit
300 terminal device
36 1 demand notification unit
362 position informati011 providing unit
25 363 measurement unit
364 measurement result acquisition unit
365 measurement result providing unit
366 communication control unit

CLAIMS
Claim 1
A communication control device comprising:
an acquisition unit configured to acquire a result of measurement perlhrmed
5 by a terminal device with regard to one or more small cells which are partly or
I entirely overlapped by a macrocell; and
a selection unit configured to select a base station which is not to be set in
an idle state from base stations of the one or more small cells based on the result of
the measurement.
Claim 2
The communication control device according to claim 1, wherein the one or
more small cells are small cells selected based on position information which
indicates a position of the terminal device.
15
Claim 3
The communication control device according to claim 1, further comprising:
a control unit configured to control the base stations of the one or more
small cells,
20 wherein the control unit refrains from causing the selected base station to be
in the idle state, and causes a base station other than the selected base stalion among
the base stations of the one or more small cells to be in the idle state.
'I
.I Claim 4
!
25 The communication control device according to claim 3, wherein the control
~i unit causes the base stations of the one or more small cells to transmit a signal for the
measurement.
Claim 5
30 The communication control device according to claim 1, further comprising:
a providing unit configured to provide information regarding the one or
11
:;
more small cells to the terminal device.
Claim 6
The cotnmunication control device according to claim 5, wherein the
5 information regarding the one or more small cells includes information which
indicates a frequency channel on which a signal for the measurement is transmitted
by each of the base stations of the one or more small cells.
Claim 7
10 The communication control device according to claim 5, wherein the
information regarding the one or more small cells includes information which
indicates a timing at which a signal for the measurement is transmitted by each of the
base stations of the one or more small cells.
j 15 Claim 8
i The communication control device according to claim 7, wherein the timing
{
depends on time taken for each of the base stations of the one or more small cells to
8 be activated from the idle state.
20 Claim 9
The comn~unication control device according to claim 7, wherein the signal
for the measurement is a reference signal.
I
I Claim 10
I 25 The communication control device according to claim 1, wherein the result
of the measurement includes information regarding reception power or quality of a
I
I signal for the measurement.
Claim 11
30 The communication control device according to claim 1, whercin the result
of the measurement is information regarding part of the one or more small cclls.
Claim 12
The communication control device according to claim I, wherein, when
reception power or quality of a signal for the measurement with regard to all of the
5 one or more small cells does not exceed a predetermined threshold value, the result
of the measurement includes information which indicates that the reception power or
the quality with regard to all of the small cells does not exceed the predetermined
threshold value.
10 Claim 13
The terminal device according to claim 1, wherein the selection unit selects
the base station that is not to be set in the idle state when notification of a demand for
performing radio communication in a small cell is given by the terminal device.
15 Claim 14
The terminal device according to claim 1,
I wherein the terminal device is able to perform radio communication using
one principal frequency baud and one or more auxiliary frequency bands, and
wherein the communication control device further includes a
20 communication control unit configured to control the terminal device to use a
frequency band for ihe macrocell as the one principal frequency band and to use a
frequency band for the small cell of the selected base station as one of the one or
more auxiliary frequency bands.
i
I
I I/ 25 Claim 15
t A communication control method comprising:
'i
acquiring a result of measurement performed by a terminal device with
!
regard to one or more small cells which are partly or entirely overlapped by a
I macrocell; and
I
30 selecting, using a processor, a base station which is not to be set in an idle
!
state from base stations of the one or more small cells based on the result of the
measurement.
Claim 16
A communication control device comprising:
5 a communication control unit configured to control transmission of a signal
for measurement performed by a terminal device with regard to a small cell which is
partly or entirely overlapped by a macrocell; and
a state control unit configured to refrain from causing a base station of the
small cell to be in an idle state when the base station of the sinall cell is selected as a
10 base station that is not to be set in the idle state based on a result of the measurement.
Claim 17
A terminal device comprising:
an acquisition unit configured to acquire a result of measurement with
15 regard to one or more small cells which are partly or entirely overlapped by a
macrocell; and
a providing unit configured to provide the result of the measurement to a
communication control device which selects a base station which is not to be set in
an idle state from base stations of the one or more small cells based on the result of
20 the measurement.