The present disclosure relates to a device and a method.
Background Art
[0002]
Currently, in the Third Generation Partnership Project (3GPP), in order to
accommodate explosively increasing traffic, various technologies for increasing the
capacity of cellular systems are being investigated. In the future, it is predicted that
15 a capacity of about 1000 times the current capacity will be necessary. Technologies
such as multi-user multiple-input multiple-output (MU-MIMO) and coordinated
multipoint (CoMP) are considered to increase the capacity of cellular systems to only
about several times the previous capacity. Therefore, a breakthrough technique is
necessary.
20 [0003]
For example, as a technique for significantly increasing the capacity of
cellular systems, a base station that uses a directional antemia including multiple
antenna elements (for example, about 100 antenna elements) and performs
beamfoi~ningi s considered. Such technology is a form of technology called large-
25 scale MIMO or massive MIMO. According to such beamforming, a half width of a
beam is narrowed. That is, a sharp beam is formed. In addition, when the
multiple antenna elements are arranged on a plane, it is also possible to form a beam
in a desired three-dimensional direction.
[0004]
30 Various beamforming technologies are proposed. For example, in Patent
Literature I, technology for implementing beamforming by a base station even when
ftequency bands of an upstream channel and a downstream chaimel are different is
disclosed.
Citation List
5 Patent Literature
[OOOS]
Patent Literature 1 JP 201 1-004056A
Summary of Invention
10 Technical Problem
[0006]
Howevel; when beamforming is performed, received quality of a reference
signal (for example, reference signal received quality (RSRQ)) may be significantly
varied. For example, interference fiom another base station may be significantly
15 varied according to which weight set is used for the other base station to perform
beamforming. Therefore, for example, a received signal strength indicator (RSSI)
significantly varies and RSRQ also significantly varies. Specifically, when the
beamforming is large-scale MIMO or massive MIMO beamforming, there is a
possibility of RSRQ being significantly greatly varied. As a result, for example, a
20 cell that is not preferable as a cell in which a terminal device performs wireless
communication (for example, a target cell of a handover) may be selected.
[0007]
Therefore, it is preferable to provide a mechanism through which it is
possible to select a cell that is more preferable for a terminal device in an
25 environment in which beamforming is performed.
Solution to Problem
[OOOS]
According to the present disclosure, there is provided a device including: ail
30 acquiring unit configured to acquire received quality information indicating received
quality of a reference signal in a terminal device; and a control unit configured to
perform cell selection for the terminal device based on the received quality
information. When a predetermined condition related to use of weight sets for
bcamforming by a base station is satisfied, the control unit does not perform the
selection based on the received quality information.
5 [0009]
According to the present disclosure, there is provided a method including:
acquiring received quality information indicating received quality of a reference
signal in a terminal device; and performing, by a processor, cell selection for the
terminal device based on the received quality information. When a predetermined
10 condition related to use of weight sets for beamforn~ingb y a base station is satisfied,
the selection is not performed based on the received quality information.
[OOIO]
According to the present disclosure, there is provided a device including: an
acquiring unit configured to acquire one or more weight sets for beamforming; and a
15 control unit configured to control wireless communication by a base station such that
the base station transmits a signal using the one or more weight sets. The control
unit controls the wireless communication such that the one or more weight sets are
used to transmit a signal in limited radio resources.
[OOll]
20 According to the present disclosure, there is provided a method including:
acquiring one or more weight sets for beamforming; and controlling, by a processor,
wireless communication by a base station such that the base station transmits a signal
using the one or more weight sets. The controlling of the wireless communication
includes controlling, by the processor, the wireless communication such that the one
25 or more weight sets are used to transmit a signal in limited radio resources.
Advantageous Effects of Invention
[0012]
According to the present disclosure described above, it is possible to select a
30 cell that is more preferable for a terminal device in an environment in which
beamforn~ing is performed. Note that the efCects described above are not
necessarily liinitative. With or in the place of the above effects, there may be
achieved any one of the effects described in this specification or other effects that
may be grasped from this specification.
Brief Description of Drawings
[0013]
[FIG. 11 FIG. 1 is an explanatory diagram for describing a weight set for large-scale
MIMO beamforming.
[FIG. 21 FIG. 2 is an explanatory diagram for describing a relation between
10 multiplication of a weight coefficient and insertion of a reference signal.
[FIG. 31 FIG. 3 is an explanatory diagram illustrating an example of a schematic
configuration of a communication system according to an embodiment of the present
disclosure.
[FIG. 41 FIG. 4 is a first explanatory diagram for describing an example of large-scale
15 MIMO beamforming.
[FIG. 51 FIG. 5 is a second explanatory diagram for describing an example of largescale
MIMO beamforming.
[FIG. 61 FIG. 6 is a block diagram illustrating an example of a configuration of a base
station according to a first embodiment.
20 [FIG. 71 FIG. 7 is an explanatory diagram for describing an example of a change of
weight sets that are used by a base station.
[FIG. 81 FIG. 8 is an explanatory diagram for describing an example of a change of a
use frequency of weight sets by a base station.
[FIG. 91 FIG. 9 is an explanatory diagram for describing an example of a use
25 frequency of weight sets by a base station.
[FIG. 101 FIG. 10 is a flowchart illustrating a first example of a schematic flow of a
cell selection process according to the first embodiment.
[FIG. 111 FIG. 11 is a flowchart illustrating a first example of a schematic flow of a
notification process according to the first embodiment.
30 [FIG. 121 FIG. 12 is a flowchart illustsating a second example of a schematic flow of
a cell selection process according to the first embodiment.
[FIG. 131 FIG. 13 is a flowchart illustrating a second example of a schematic flow of
a notification process according to the first embodiment.
[FIG. 141 FIG. 14 is a block diagram illustrating an example of a configuration of a
terminal device according to a second embodiment.
5 [FIG. 151 FIG. 15 is a block diagram illustrating an example of a configuration of a
base station according to the third embodiment.
[FIG. 161 FIG. 16 is an explanatory diagram for describing an example of
beamforming in some bands.
[FIG. 171 FIG. 17 is a flowchart illustrating an example of a schematic flow of a
10 process according to the third embodiment.
[FIG. 181 FIG. 18 is a block diagram illustrating a first example of a schematic
configuration of an eNB.
[FIG. 191 FIG. 19 is a block diagram illustrating a second example of the schematic
configuration of the eNB.
15 [FIG. 201 FIG. 20 is a block diagram illustrating an example of a schematic
configuration of a smartphone.
[FIG. 211 FIG. 21 is a block diagram illustrating an example of a schematic
configuration of a car navigation apparatus.
20 Description of Embodiment(s)
[0014]
Hereinafter, (a) preferred embodiment(s) of the present disclosure will be
described in detail with reference to the appended drawings. In this specification
and the drawings, elements that have substantially the same function and structure
25 are denoted with the same reference signs, and repeated explanation is omitted.
[0015]
In this specification and the drawings, there are cases in which components
having substantially the same functional configuration are distinguished by adding
different alphabets to the end of the same reference numeral. For example, a
30 plurality of components having substantially the same functional configuration are
distinguished like terminal devices 200A, 200B, and 200C as necessary. However,
whcn a plurality of components having substantially the same functional
configuration need not be particularly distinguished, only the same reference numeral
is added. For example, when the terminal devices 200A, 200B, and 200C need not
be particularly distinguished, they are referred to simply as a "terminal devices 200."
5 [0016]
The description will proceed in the following order.
1. Introduction
2. Schematic configuration of communication system
3. First embodiment
10 3.1. Configuration of base station
3.2. Process flow
4. Second embodiment
4.1. Configuration of terminal device
4.2. Process flow
15 5. Third embodiment
5.1. Configuration of base station
5.2. Process flow
6. Application examples
6.1. Application examples for base station
20 6,2. Application examples for termilral device
7. Conclusion
[OO 171
<>
First, beamfornling, measurement and cell selection will be described with
25 reference to FIG. 1 and FIG. 2.
[0018]
(Reamfolming)
(a) Necessity of large-scale MIMO
Currently, in the 3GPP, in order to accommodate explosively increasing
30 traffic, various technologies for increasing the capacity of ccllular systems are being
investigated. In the future, it is predicted that a capacity of about 1000 times the
current capacity will be necessary. Technologies such as MU-MIMO and CoMP are
considered to increase the capacity of cellular systems to only about several times the
previous capacity. Therefore, a breakthrough technique is necessaly.
[00 191
5 In 3GPP release 10, an eNodeB in which eight antemias are implemented is
standardized. According to the antennas, eight-layer MIMO can be implemented in
single-user multiple-input multiple-output (SU-MIMO). 8-layer MIMO is
technology in which eight independent streams are spatially multiplexed. In
addition, it is possible to implement two-layer MU-MIMO with four users.
10 [0020]
In user equipment (UE), it is difficult to increase the number of antenna
elements of an antenna of the UE due to a small space for arranging antennas and a
limited UE processing capacity. However, according to recent advances in antenna
mounting technology, it is possible to arrange a directional antenna including about
15 100 antenna elements in an eNodeB.
[0021]
For example, as a technique for significantly increasing the capacity of
cellular systems, a base station that uses a directional antenna including multiple
antenna elements (for example, about 100 antenna elements) and performs
20 beamforming is considered. Such technology is a form of technology called largescale
MIMO or massivk MIMO. According to such beamforming, a half width of a
beam is narrowed. That is, a sharp beam is formed. In addition, when the
multiple antenna elements are arranged on a plane, it is also possible to form a beam
in a desired three-dimensional direction. For example, a technique is proposed in
25 which a beam directed toward a position higher than a base station (for example, an
upper floor of a high-rise building) is formed, and thus a signal is transmitted to a
terminal device in such a position.
[0022]
In typical beamforming, it is possible to change a direction of a beam in a
30 horizontal direction. Therefore, the typical beamfonning may be referred to as twodimensional
beamforming. On the other hand, in large-scale MIMO (or massive
MIMO) beamforming, it is possible to change a direction of a beam in a vertical
direction in addition to the horizontal direction. Therefore, the large-scale MIMO
beamfornling may be referred to as three-dimensional beamfornling.
[0023]
5 Since the number of antennas increases, it is possible to increase the number
of users of MU-MIMO. Such technology is another form of technology called
large-scale MIMO or massive MIMO. When the number of antennas of a UE is 2,
the number of streams that are spatially independent in a single UE is 2. Therefore,
increasing the number of users of MU-MIMO is more reasonable than increasing the
10 number of streams in a single UE.
[0024]
(b) Weight set
A weight set for beamforming (that is, a set of weight coefficients for
multiple antenna elements) is represented as a complex number. Hereinafter, an
15 example of a weight set for large-scale MIMO beamforming will be described
specifically with reference to FIG. 1.
[0025]
FIG. 1 is an explanatory diagram for describing a weight set for large-scale
MIMO beamforming. Referring to FIG. 1, antenna elements arranged in a grid
20 pattern are shown. In addition, two orthogonal axes x and y on a plane in which
antenna elements are arranged and one axis z orthogonal to the plane are shown.
Here, a direction of a beam to be formed is indicated by, for example, an angle phi (a
Greek letter) and an angle theta (a Greek letter). The angle phi (a Greek letter) is an
angle formed by a component of an xy plane within a beam direction and the x axis.
25 In addition, the angle theta (a Greek letter) is an angle formed by a beam direction
and the z axis. In this case, for example, a weight coefficient V,,, of an antenna
element that is arranged at an m-th point in an x axis direction and arranged at an nth
point in a y axis direction may be represented as follows.
[0026]
30 [Math. 11
[0027]
f denotes a frequency and c denotes the speed of light. j denotes an
imaginary unit of a complex number. d, denotes an interval between antenna
5 elements in the x axis direction. d, denotes an interval between antenna elements in
the y axis direction. Coordinates of the antenna element are represented as follows.
[OOZS]
[Math. 21
10 LO0291
A weight set for typical beamforming (two-dimensional beamforming) may
be decomposed into a weight set for forming a beam in a desired horizontal direction
and a weight set for adjusting transfer between antennas. Therefore, a weight set
for large-scale MIMO beamforming may be decomposed into a first weight set for
15 forming a beam in a desired vertical direction, a second weight set for forming a
beam in a desired horizontal direction and a third weight set for adjusting transfer
between antennas.
[0030]
(c) Change of environment according to large-scale MIMO beamforming
20 When large-scale MIMO beamforming is performed, a gain reaches 10 dB
or more. A change of a radio wave environment of a cellular system using the
beanlfotming may be greater than a cellular system of the related art.
[003 11
(d) Case in which large-scale MIMO beamforming is performed
25 For example, a base station of an urban area forming a beam directed
toward a high-rise building is considered. In addition, even in a suburb, a base
station of a small cell is considered to form a beam directed toward an area around
the base station. A base station of a suburban macro cell is unlikely to perforni
large-scale MIMO beamforming.
[003 21
(Measurement)
(a) CRS Measurement
In Long Term Evolution (LTE), a terminal device performs measurement of
5 a cell-specific reference signal (CRS) transmitted by a base station. Specifically,
the telminal device receives a CRS transmitted by a base station and thus performs
measurement of quality of a propagation path between the base station and the
terminal device. The measurement is referred to as "radio resource management
(RRM) measurement," or is simply referred to as "measurement."
10 [0033]
A result of the measurement is used to select a cell for a terminal device.
As a specific example, the result of the measurement is used for cell selection/cell
reselection by a terminal device that is in a radio resource control (RRC) idle (RRC
Idle) state. In addition, for example, the result of the measurement is reported to a
15 base station by a telminal device that is in an RRC connected state and is used for a
handover decision by the base station.
[0034]
As described above, measurement is performed by receiving a CRS. Since
the CRS is a signal for measuring quality of a transmission path of omnidirectional
20 radio waves, it is transmitted without beamforming. That is, the CRS is transmitted
without multiplying the weight set for beamforming.
[0035]
There is a reference signal for demodulation called a demodulation
reference signal (DM-RS) or a UE-specific reference signal. Since the reference
25 signal for demodulation is multiplied by the weight set for beamforming, it is not
preferable to measure quality of a transmission path of omnidirectional radio waves.
In addition, there is a reference signal called a channel state information reference
signal (CSI-RS). Similarly to the CRS, the CSI-RS is transmitted without
beanlforming. However, since a transmission frequency of the CSI-RS is low,
30 measurement by receiving the CSI-RS consumes much time. Hereinafter, a relation
between multiplication of a weight coefficient and insei.tion (or mapping) of a
reference signal will be described with refcrcnce to FIG. 2.
[0036]
FIG. 2 is an explanatory diagram for describing a relation between
multiplication of a weight coefficient and inseltion of a reference signal. Referring
5 to FIG. 2, a transmission signal 92 corresponding to each antenna element 91 is
complex-multiplied by a weight coefficient 93 in a multiplier 94. Then, the
transmission signal 92 complex-multiplied by the weight coefficient 93 is transmitted
from the antenna element 91. In addition, a DR-MS 95 is inserted before the
multiplier 94, and the weight coefficient 93 is complex-multiplied in the multiplier
10 94. Then, the DR-MS 95 complex-multiplied by the weight coefficient 93 is
transmitted from the antenna element 91. On the other hand, a CRS 96 (and CSIRS)
is inserted after the multiplier 94. Then, the CRS 96 (and CSI-RS) is
transmitted from the antenna element 91 without being multiplied by the weight
coefficient 93.
15 [0037]
(b) RSRP and RSRQ
In LTE, CRS measurement is measurement of reference signal received
power (RSRP) and/or reference signal received quality (RSRQ). In other words, a
terminal device acquires RSRP and/or RSRQ as a result of the measurement of the
20 CRS. The RSRQ is calculated from the RSRF' and a received signal strength
indicator (RSSI).
[003 81
The RSRP is received power of a CRS for each single resource element.
That is, the RSRP is an average value of received power of the CRS. The received
25 power of the CRS is obtained by detecting a correlation between a reception signal in
a resource element of the CRS and a known signal CRS. The RSRF' corresponds to
a desired signal "Signal (S)."
[0039]
The RSSI is total power of signals for each Orthogonal Frequency Division
30 Multiple Access (OFDMA) symbol. Therefore, the RSSI includes a desired signal,
an interferencc signal and noise. That is, the RSSI corresponds to "Signal
(S)+lnterference (I)+Noise (N)."
[0040]
The RSRQ is RSRP/(RSSVN). N denotes the number of resource blocks
used for calculating an RSSI. The resource blocks are resource blocks that are
5 arranged in a fiequency direction. Therefore, the RSRQ is a value that is obtained
by dividing the RSRP using the RSSI for each resource block. That is, the RSRQ
corresponds to a signal-to-interference-plus-noise ratio (SINR).
[0041]
As described above, according to the measurement of the CRS, received
10 power (that is, RSRP) and received quality (that is, RSRQ) such as an SINR are
obtained.
100421
(c) Effect of averaging
In order to acquire the RSRP and the RSRQ, it is necessary to receive
15 signals for several milliseconds to several tens of milliseconds and perform
averaging of received power thereof. This is because, a result is likely to be
influenced by an instantaneous variation of a channel such as fading when the RSRP
and the RSRQ are acquired by averaging only one slot or one subset.
[0043]
20 A technique of averaging is implemented for each terminal device and is not
specifically defined in the specification.
[0044]
(Cell selection)
(a) Example of cell selection
25 For example, when a terminal device is in an RRC idle state, cell
selection/cell reselection is performed. That is, the terminal device selects a cell for
performing communication (for example, a cell for receiving paging).
[0045]
In addition, for example, a base station performs a handover decision.
30 That is, the base station selects a target cell for the terminal device and decides
whether a handover from a serving cell for the teiminal device to the target cell is
performed.
[0046]
In addition, for example, the base station adds a secondary cell (Scell) of
carrier aggregation. The Scell is also called a secondary component carrier (SCC).
5 [0047]
Were, the term "cell" may refer to a cornmullication area of the base station
or a frequency band that the base station uses. In addition, the term "cell" may refer
to a primary cell (Pcell) or an Scell of carrier aggregation. The Pcell is also called a
primary component carrier (PCC). The Scell is also called a secondary component
10 carrier (SCC).
[0048]
(b) Cell selection when beamforming is performed
As described above, in the form of the technology called large-scale MIMO
or massive MIMO, the base station performs beamforming using a directional
15 antenna including multiple antenna elements (for example, about 100 antenna
elements). In this case, the base station can change a direction of a beam in not
only the horizontal direction but also the vertical direction. Therefore, as an
example, when the base station forms a beam directed toward a position (for example,
an upper floor of a high-rise building) higher than the base station, it is possible to
20 increase throughput at the high position. As another example, when a small base
station forms a beam toward a nearby area, it is possible to reduce interference with
an adjacent base station.
[0049]
Here, when transmission and reception of signals according to large-scale
25 MIMO beamforming become a main flow, there is a question of whether cell
selection may be performed based on the result of measurement of the CRS.
[OOSO]
Specifically, only quality of a transmission path of omnidirectional radio
waves can be understood from measurement of the CRS. However, the
30 transmission path of omnidirectional radio waves is completely different from a
transmission path of a sharp beam that is formed according to large-scale MIMO
beamforming. Therefore, when transmission and reception of signals according to
the beamforming are assumed, there is a possibility of an appropriate cell not being
selected in cell selection based on the result of measurement of the CRS.
[0051]
5 As an example, when a terminal device transmits and receives signals in a
cell selected based on the result of measurement of the CRS, there is a possibility of
a great amount of interference due to a s h a b~e am from an adjacent base station.
As another example, even if a result of measurement of a CRS of a certain cell is
more favorable than a result of measurement of a CRS of another cell, there is a
10 possibility of communication quality of the other cell being more favorable than
communication quality of the certain cell when beamforming is performed.
[0052]
As described above, there is a possibility of an appropriate cell for a
terminal device not being selected when beamforming is performed.
15 [0053]
(c) Case in which measurement of a CRS is not preferable
As described above, for example, large-scale MIMO beamforming is
considered to be performed by a base station of an urban area or a base station of a
small cell. Therefore, it is not preferable for such base stations to perform cell
20 selection based 011 measurement of a CRS.
[0054]
<<2. Schematic configuration of communication system>>
Next, a schematic configuration of a communication system 1 according to
an embodiment of the present disclosure will be described with reference to FIGS. 3
25 to 5. FIG. 3 is an explanatory diagram illustrating an example of the schematic
configuration of the communication system 1 according to the embodiment of the
present disclosure. Referring to FIG. 3, the communication system 1 includes a
base station 100 and a terminal device 200. The communication system 1 is a
system supporting, for example, LTE, LTE-Advanced, or a con~munications tandard
30 equivalent thereto,
[0055]
(Base station 100)
The base station 100 wirelessly communicates with a terminal devicc. For
example, the base station 100 wirelessly communicates with a terminal device that is
positioned within a communication area of the base station 100 (including, for
5 example, the terminal device 200).
(Terminal device 200)
The terminal device 200 wirelessly communicates with a base station. For
example, when the terminal device 200 is positioned within the communication area
of the base station 100, the terminal device 200 wirelessly commu~licates with the
10 base station 100.
[0056]
(Environment in which beamforming is performed)
Specifically, in an embodiment of the present disclosure, beamforming is
performed by a base station. The base station includes, for example, the base
15 station 100 and a neighbor base station of the base station 100. For example, the
beamforming is large-scale MIMO beamforming. The beamforming may also be
referred to as massive MIMO beamforming or three-dimensional beamfoiming.
[0057]
As a specific example, the base station (for example, the base station 100
20 and the neighbor base station) includes a directional antenna capable of large-scale
MIMO. In addition, the base station multiplies a transmission signal by a weight
set for the directional antenna and thus performs large-scale MIMO beamforming.
For example, the weight set is decided for each teiminal device (for example, the
terminal device 200). As a result, a beam directed toward the terminal device is
25 formed. Hereinafter, an example of large-scale MIMO beamforming will be
described with reference to FIG. 4 and FIG. 5.
[005S]
FIG. 4 is a first explanatory diagram for describing an example of largescale
MIMO beamforming. Referring to FIG. 4, a directional antenna 101 available
30 for large-scale MIMO is shown. Thc directional antenna 101 can form a sharp
beam in a desired three-dimensional direction. For example, a beam 21A and a
beam 21B are formed by the directional antenna 101.
[0059]
FIG. 5 is a secondary explanatory diagram for describing an example of
large-scale MIMO beamforming. Referring to FIG. 5, the beams 21A and 21B
5 described with reference to FIG. 4 are shown. For example, the beam 21A reaches
an area 23A and the beam 21B reaches an area 23B. Therefore, a terminal device
200A positioned within the area 23.4 can receive a signal transmitted as the beam
21A. In addition, a terminal device 200B positioned within the area 23B can
receive a signal transmitted as the beam 21B. The base station 100 transmits a
10 signal addressed to the terminal device 200A as the beam 21A and transmits a signal
addressed to the terminal device 200B as the beam 21B.
[0060]
The base station (for example, the base station 100 and the neighbor base
station) can transmit, for example, a signal without beamforming. As an example,
15 the base station includes an omnidirectional antenna and transmits a signal as
omnidirectional radio waves. As another example, the base station includes a sector
antenna and may transmit a signal as a sector beam.
[0061]
<<3. First embodiment>>
20 Next, a first embodiment of the present disclosure will be described with
reference to FIG. 6 to FIG. 13.
[0062]
In the first embodiment, a base station 100-1 performs cell selection for a
terminal device 200-1 based on received quality information indicating received
25 quality of a reference signal in the telminal device 200-1. Specifically, when a
predetermined condition related to use of weight sets for beamforming by the base
station is satisfied, the base station 100-1 does not perform the selection based on the
received quality information.
[0063]
30 Accordingly, for example, it is possible to select a cell that is more
preferable for the terminal device 200-1 in an environment in which beamfo~mingis
performed.
[0064]
<3.1. Configuration of base station>
First, an example of a configuration of the base station 100-1 according to
5 the first embodiment will be described with reference to FIG. 6 to FIG. 9. FIG. 6 is
a block diagram illustrating an example of the configuration of the base station 100-1
according to the first embodiment. As illustrated in FIG. 6, the base station 100-1
includes an antenna unit 110, a wireless communication unit 120, a network
communication unit 130, a storage unit 140 and a processing unit 150.
10 [0065]
(Antenna unit 1 10)
The antenna unit 110 emits a signal output by the wireless communication
unit 120 into space as radio waves. In addition, the antenna unit 110 converts
spatial radio waves into a signal, and outputs the signal to the wireless
15 communication unit 120.
[0066]
For example, the antenna unit 110 includes a directional antenna. For
example, the directional antenna is a directional antenna capable of large-scale
MIMO.
20 [0067]
In addition, for example, the antenna unit 110 further includes an
omnidirectional antenna. Alternatively, the antenna unit 110 may include a sector
antenna with or without an omnidirectional antenna.
[0068]
25 (Wireless communication unit 120)
The wireless communication unit 120 transmits and receives signals. For
example, the wireless communication unit 120 transmits a downlink signal to the
terminal device 200-1 and receives an uplink signal from the terminal device 200-1.
[0069]
30 (Network comnunication unit 130)
The network communication unit 130 transmits and receives information.
For example, the network communication unit 130 transmits information to another
node and receives information from the other nodc. For examplc, the other node
includes another base station and a core network node.
[0070]
5 (Storage unit 140)
The storage unit 140 stores programs and data for operations of the base
station 100-1.
[0071]
(Processing unit 150)
10 The processing unit 150 provides various functions of the base station 100-1.
The processing unit 150 includes an information acquiring unit 15 1 and a control unit
153. Alternatively, the processing unit 150 may further include a component other
than these components. That is, the processing unit 150 may also perform an
operation other than operations of these components.
15 [0072]
(Information acquiring unit 15 1)
The information acquiring unit 151 acquires received quality information
indicating received quality of a reference signal in the terminal device 200-1.
[0073]
20 (a) Received quality
For example, the received quality is reference signal received quality
(RSRQ). That is, the received quality information is information indicating RSRQ.
[0074]
For example, the reference signal is a reference signal that is transmitted in
25 a frequency band. The frequency band is, for example, a component carrier (CC) of
carrier aggregation. For example, the reference signal is a cell-specific reference
signal (CRS).
[0075]
(b) Terminal device
30 For example, the terminal device 200-1 is a terminal device that is
connected to the base station 100-1.
(c) Acquiring method
For example, the terminal device 200-1 measures received quality and
reports received quality information indicating the received quality to the base station
5 100-1 as a measurement result. That is, the received quality information is
information that is reported by the terminal device 200-1 to the base station 100-1 to
which the terminal device 200-1 is connected. Then, the received quality
information is stored in the storage unit 140. The information acquiring unit 151
acquires the received quality information from the storage unit 140 at any timing
10 thereafter.
[0077]
(Control unit 153)
The control unit 153 performs cell selection for the terminal device 200-1
based on the received quality information. Specifically, in the first embodiment,
15 when the predetermined condition related to the use of the weight sets for
bearnforming by the base station (hereinafter referred to as a "weight-use-related
condition") is satisfied, the control unit 153 does not perform the selection based on
the received quality information.
[0078]
20 (a) Cell selection
As a first example, the cell is a target cell of a handover of the terminal
device 200-1. That is, the control unit 153 selects a target cell of the handover of
the terminal device 200-1 based on the received quality information. Then, for
example, the control unit 153 decides whether to perform the handover.
25 [0079]
As a second example, the cell is a secondary cell of carrier aggregation for
the terminal device 200-1. That is, the control unit 153 selects a secondary cell of
carrier aggregation of the terminal device 200-1 based on the received quality
information. Then, for example, the control unit 153 activates or deactivates the
30 secondary cell.
[0080]
(b) Weight-use-related condition
(b-1) Base station
For example, the base station is the base station 100-1 to which the terminal
device 200-1 is connected or a neighbor base station of the base station 100-1. That
5 is, the weight-use-related condition is a predetermined condition related to use of a
weight set by the base station 100-1 to which the terminal device 200-1 is connected
or the neighbor base station of the base station 100-1.
[0081]
(b-2) Weight set for beamforming
10 For example, a weight set used by the base station is a weight set for largescale
MIMO beamforming (or massive MIMO beamforming or three-dimensional
beamforming).
[0082]
Alternatively, the weight set used by the base station may be a weight set for
15 an existing type of beamforming (for example, two-dimensional beamforming).
[0083]
(b-3) Frequency band
As described above, for example, the reference signal is a reference signal
that is transmitted in a frequency band (for example, a CC). Thus, the weight-use-
20 related condition is a condition related to use of the weight sets for beamforming by
the base station in the frequency band (for example, the CC).
[0084]
(b-4) First example of weight-use-related condition (change of use situation of
weight set)
25 As a first example, the weight-use-related condition is a condition that a use
situation of the weight sets for beamforming by the base station be changed by a
predetermined degree or more. That is, when a use situation of weight sets by the
base station (for example, the base station 100-1 or the neighbor base station) is
changed by the predetermined degree or more, the control unit 153 does not perform
30 the selection based on the received quality information.
[0085]
Accordingly, for example, when a beam emitted by the base station is
changed to sonle extent or more and reliability of the received quality information is
decreased as a result, cell selection is not perfo~med based on the received quality
information. Therefore, a possibility of a cell that is not preferable for the terminal
5 device 200-1 being selected may be decreased. In other words, a cell that is more
preferable for the telminal device 200-1 may he selected.
[0086]
- Weight set
-- Some of weight sets
10 For example, the weight-use-related condition is a condition that a use
situation of some of the weight sets for heamforming by the base station be changed
by the predetermined degree or more. That is, when the use situation of some of the
weight sets for beamforming by the hase station is changed by the predetermined
degree or more, the control unit 153 does not perform the selection based on the
15 received quality information. In other words, weight sets serving as targets of
changes of use situations are some of the weight sets that are used by the base station.
[0087]
As an example, some of the weight sets for beamforming may be weight
sets that are used at a higher frequency (that is, weight sets used in more radio
20 resources). As another example, some of the weight sets for bea~nfoimingm ay be
weight sets except a weight set of a beam directed toward a central poi-tion of a cell
of the base station (for example, a weight set of a beam directed toward a cell edge).
[OOSS]
-- All weight sets
25 The weight-use-related condition may be a condition that use situations of
all of the weight sets for beamforming by the base station be changed by the
predetermined degree or more. That is, when use situations of all of the weight sets
for beamfoiming by the hase station are changed by the predetermined degree or
more, the control unit 153 may not perforln the selection based on the received
30 quality infonnation. In other words, weight sets serving as targets of changes of use
situations may be all of the weight sets that are used by the base station.
LOO891
- Change of use situation
-- Change of weight set to be used
As a first specific example, the weight-use-related condition is a condition
5 that the weight sets for beamforming used by the base station be changed by a
predetermined degree or more. That is, when weight sets used by the base station
(for example, the base station 100-1 or the neighbor base station) are changed by the
predetermined degree or more, the control unit 153 does not perform the selection
based on the received quality information.
10 [O090]
For example, when a predetermined number or more weight sets among
weight sets used by the base station are changed in a short period, the control unit
153 does not perform the selection based on the received quality information.
Hereinafter, this will be described with reference to a specific example of FIG. 7.
15 [0091]
FIG. 7 is an explanatory diagram for describing an example of a change of
weight sets used by a base station. Referring to FIG. 7, a period 31, a period 33 and
a period 35 are shown. In this example, the base station transmits a signal using a
weight set of V1, V2 and V3 in the period 3 1, transmits a signal using a weight set of
20 V1 and V2 in the period 33, and transmits a signal using a weight set of V5, V6 and
V7 in the period 35. That is, one weight set among weight sets used by the base
station is changed at a time point 37, and three weight sets among the weight sets
used by the base station are changed at a time point 39. For example, when two or
more weight sets are changed in a short period, the control unit 153 does not perform
25 measurement based on the received quality information. In this case, the control
unit 153 determines that two or more weight sets are changed in a short period based
on the change of weight sets at the time point 39 and does not perform cell selection
for the terminal device 200-1 based on the received quality infoimation.
[0092]
30 It sliould be noted that a change of weight sets used by the base station by
the predetermined degree or more is not limited to the above example (a change of
the predetermined number or more weight sets). Various changes may be applied.
As an example, a distance between weight set groups is defined, and whcn weight set
groups used by the base station are changed by a predetermined distance or more in a
short period, the conwol unit 153 may not perform the selection based on the
5 received quality information.
[0093]
For example, as described above, when weight sets used by the base station
are changed by the predetermined degree or more, the control unit 153 does not
perform the selection based on the received quality information. Accordingly, for
10 example, when a direction of a beam emitted by the base station is changed to some
extent or more and reliability of the received quality information is decreased as a
result, cell selection is not performed based on the received quality information.
Therefore, a possibility of a cell that is not preferable for the terminal device 200-1
being selected may be decreased.
15 [0094]
-- Change of use frequency of weight sets
As a second specific example, the weight-use-related condition is a
condition that a use frequency of the weight sets for beamforming by the base station
be changed by a predetermined degree or more. That is, when a use frequency of
20 weight sets by the base station (for example, the base station 100-1 or the neighbor
base station) is changed by the predetermined degree or more, the control unit 153
does not perform the selection based on the received quality information.
[0095]
For example, the use frequency is an amount or a ratio of radio resources
25 through which the base station transmits a signal using a weight set for beamforming,
and a predetermined frequency is a predetermined amount or ratio. That is, when
an amount or a ratio of radio resources through which the base station (for example,
the base station 100-1 or the neighbor base station) transmits a signal using a weight
set is changed by a predetermined amount or a predetermined ratio or more, the
30 control unit 153 does not perform the selection based on the received quality
information. Iiereinnfter, this will be described with reference to a specific exa~nple
of FIG. 8.
[0096]
FIG. 8 is an explanatory diagram for describing an example of a change of a
use frequency of weight sets by a base station. Referring to FIG. 8, a period 41, a
5 period 43 and a period 45 are shown. In this example, the base station transmits a
signal using a weight set in 50 RBs (50%) among 100 resource blocks (RBs) across a
component carrier (CC) having a bandwidth of 20 MHz in the period 41. Further,
the base station transmits a signal using a weight set in 55 RBs (55%) in the period
43, and transmits a signal using a weight set in 80 RBs (80%) in the period 45.
10 That is, the number of RBs through which a signal is transmitted using a weight set
increases by 5 (5%) at a time point 47 and the number of RBs through which a signal
is transmitted using a weight set increases by 25 (25%) at a time point 49. For
example, when the number of RBs through which a signal is transmitted using a
weight set increases or decreases by 20 (20%) in a short period, the control unit 153
15 does not perform measurement based on the received quality information. In this
case, the control unit 153 determines that the number of RBs through which a signal
is transmitted using a weight set is changed by 20 or more in a short period based on
the change in the number of RBs at the time point 49 and does not perform cell
selection for the terminal device 200-1 based on the received quality information.
20 [0097]
Accordingly, for example, when an amount of beams emitted by the base
station is changed to some extent or more and reliability of the received quality
information decreases as a result, cell selection is not performed based on the
received quality information. Therefore, a possibility of a cell that is not preferable
25 for the terminal device 200-1 being selected may be decreased
[0098]
- Cell selection after change
For example, after the weight-use-related condition is satisfied, the control
unit 153 does not perform the selection based on the received quality information for
30 a predetermined period. In addition, for example, the control unit 153 performs the
selection based on the received quality information after the predetermined period
has elapsed.
100991
Accordingly, for example, cell selection is not performed based on received
quality information having low reliability immediately after a beam emitted by the
5 base station is changed. Then, after a while fiom when the beam is changed, cell
selection may be performed based on received quality information indicating
received quality in an environment of the changed beam (that is, received quality
information having high reliability). Therefore, a cell that is more preferable for the
terminal device 200-1 may be selected.
10 [OlOO]
Learning about use situation of weight set
For example, the control unit 153 can identify the use situation of the weight
sets for beamforming by the base station 100-1. Therefore, the control unit 153 can
determine whether the weight-use-related condition for the base station 100-1 is
15 satisfied.
[OlOl]
For example, a neighbor base station notifies the base station 100-1 of
information about a use situation of the weight sets for beamfonning by the neighbor
base station of the base station 100-1. The neighbor base station may notify the
20 base station 100-1 that the use situation is changed by the predetermined degree or
more or notify the base station 100-1 of the use situation itself (for example, a weight
set to be used or a use frequency of weight sets). Therefore, the control unit 153
can determine whether the weight-use-related condition for the neighbor base station
is satisfied.
25 [0102]
For example, the base station 100-1 notifies the neighbor base station of the
base station 100-1 of information about the use situation of the weight sets for
beamfonning by the base station 100-1. The base station 100-1 may notify the
neighbor base station that the use situation is changed by the predetermined degree or
30 more or may notify the neighbor base station of the use situation itself. Accordingly,
for example, the neighbor base station can determine whether the weight-use-related
condition for the base station 100-1 is satisfied.
[0103]
(b-5) Second example of weight-use-related condition (use frequency of weight sets)
As a second example, the weight-use-related condition is a condition that a
5 use frequency of the weight sets for beamforming by the base station be equal to or
greater than the predetermined frequency. That is, when the use frequency of the
weight sets for beamforming by the base station is equal to or greater than the
predetermined frequency, the control unit 153 does not perform the selection based
on the received quality information.
10 [0104]
- Weight set
-- Some of weight sets
For example, the weight-use-related condition is a condition that a use
frequency of some of the weight sets for beamforming by the base station be equal to
15 or greater than the predetermined frequency. That is, when the use frequency of
some of the weight sets for beamforming by the base station is equal to or greater
than the predetermined frequency, the control unit 153 does not perform the selection
based on the received quality information. In other words, weight sets serving as
targets of a use frequency are some of weight sets that are used by the base station.
20 [0105]
As an example, some of the weight sets for beamforming may be weight
sets that are used at a higher frequency (that is, weight sets used for more radio
resources). As another example, some of the weight sets for beamforming may be
weight sets except a weight set of a beam directed toward a central portion of a cell
25 of the base station (for example, a weight set of a beam directed toward a cell edge).
[O 1061
-- All weight sets
The weight-use-related condition is a condition that a use frequency of all of
the weight sets for beamforming by the base station be equal to or grcater than the
30 predetermined frequency. That is, when the use frequency of all of the weight sets
for beamforming by the base station is equal to or greater than the predetermined
frequency, the control unit 153 may not perform the selection based on the received
quality information. In other words, weight sets serving as targets of a use
frequency may be all weight sets used by the base station.
[O 1071
5 Accordingly, for example, when an amount of beams emitted by the base
station is an amount of some extent or more, received quality is greatly influenced by
the beams and reliability of the received quality information decreases as a result so
that cell selection is not performed based on the received quality information.
Therefore, a possibility of a cell that is not preferable for the terminal device 200-1
10 being selected may be decreased. In other words, a cell that is more preferable for
the terminal device 200-1 may be selected.
[0108]
- Use frequency of weight sets
For example, the use frequency is an amount or a ratio of radio resources
15 through which the base station transmits a signal using a weight set for beamforming,
and the predetermined frequency is a predetermined amount or ratio. That is, when
an amount or a ratio of radio resources through which the base station transmits a
signal using a weight set for beamforming is equal to or greater than the
predetermined amount or ratio, the control unit 153 does not perform the selection
20 based on the received quality information. Hereinafter, this will be described with
reference to a specific example of FIG. 9.
[0109]
FIG. 9 is an explanatory diagram for describing an example of a use
frequency of weight sets by a base station. Referring to FIG. 8, a period 51, a
25 period 53 and a period 55 are shown. In this example, the base station transmits a
signal using a weight set in 30 RBs (30%) among 100 RBs across a CC having a
bandwidth of 20 MHz in the period 51. Further, the base station transmits a signal
using a weight set in 60 RBs (60%) in the period 53, and transmits a signal using a
weight set in 45 RBs (45%) in the period 55. For example, when a signal is
30 transmitted using a weight set in 50 RBs (50%) or more, the control unit 153 does
not perform measurement based on the received quality information. In this case,
the control unit 153 determines that a signal is transmitted using a weight set in 50
RBs or more in the period 53 and does not perform cell selection for the terminal
device 200-1 based on the received quality i~lEormation. In addition, the control
unit 153 determines that a signal is not transmitted using a weight set in 50 RBs
5 (50%) or more in the period 5 1 and the period 53 and performs cell selection for the
terminal device 200-1 based on the received quality information.
[OllO]
- Learning about use frequency of weight sets
For example, the control unit 153 can identify a use frequency of the weight
10 sets for beamforming by the base station 100-1. Therefore, the control unit 153 can
determine whether the weight-use-related condition for the base station 100-1 is
satisfied.
[Olll]
For example, a neighbor base station notifies the base station 100-1 of
15 information about a use frequency of the weight sets for beamforming by the
neighbor base station of the base station 100-1. The neighbor base station may
notify the base station 100-1 that the use frequency is equal to or greater than the
predetermined frequency or may notify the base station 100-1 of the use frequency
itself. Therefore, the control unit 153 can determine whether the weight-use-related
20 condition for the neighbor base station is satisfied.
[0112]
For example, the base station 100-1 notifies the neighbor base station of the
base station 100-1 of information about the use frequency of the weight sets for
beamforming by the base station 100-1. The base station 100-1 may notify the
25 neighbor base station that the use frequency is equal to or geater than the
predetermined frequency or may notify the neighbor base station of the use
frequcncy itself. Accordingly, for example, the neighbor base station can determine
whether the weight-use-related condition for the base station 100-1 is satisfied.
[0113]
30 (b-6) Operation when wcight-use-related condition is satisfied
As described above, when the weight-use-related condition is satisfied, the
control unit 153 does not perform thc selection based on thc received quality
information. When the use-related condition is satisfied, the control unit 153 may
not perform the selection itself or may perform the selection based on infornlation
other than the received quality information (for example, received power information
5 such as RSRP).
[0114]
<3.2. Process flow>
Next, examples of processes according to the first embodiment will be
described with reference to FIG. 10 to FIG. 13.
10 [0115]
(Case of first example of weight-use-related condition)
First, a process related to a case in which a first example of the weight-userelated
condition is applied will be described. The first example of the weight-userelated
condition is a condition that a use situation of the weight sets for
15 beamforming by the base station be changed by a predetermined degree or more.
[0116]
(a) Cell selection process
FIG. 10 is a flowchart illustrating a first example of a schematic flow of a
cell selection process according to the first embodiment.
20 (01171
The information acquiring unit 15 1 acquires received quality information
indicating received quality of a reference signal in the terminal device 200-1, and the
control unit 153 performs cell selection for the terminal device 200-1 based on the
received quality information (S401).
25 [0118]
The control unit 153 determines whether a use situation of weight sets by
the base station (for example, the base station 100-1 or a neighbor base station) is
changed by a predetermined degree or more (S403). When the use situation is not
changed by the predetermined degree or more, the process returns to Step S401.
30 [0119]
When the use situation is changed by the predetermined degree or more, the
control unit 153 starts a timer (S405).
[0120]
Then, the control unit 153 does not perform cell selection for the terminal
device 200-1 based on the received quality information (S407). This continues as
5 long as the timer has not expired (NO in S409). That is, the control unit 153 does
not perform the selection based on the received quality information for a
predetermined period.
[0121]
When the timer expires (YES in S409), the process returns to Step S401.
10 [0122]
(b) Notification process
FIG. 11 is a flowchart illustrating a first example of a schematic flow of a
notification process according to the first embodiment.
[0123]
15 The control unit 153 resets a timer (S421). It is determined whether a use
situation of weight sets by the base station 100-1 is changed by a predetermined
degree or more (S423). When the use situation is not changed by the predetermined
degree or more (NO in S423), the process returns to Step S421.
[0 1241
20 When the use situation is changed by the predetermined degree or more
(YES in S423), the control unit 153 starts the timer (S425).
[0125]
Then, the control unit 153 determines whether a change of the use situation
is temporary (S427). That is, the control unit 153 determines whether the use
25 situation is returned to its origin. The determination continues as long as the timer
has not expired (NO in S429). When the change of the use situation is temporary
(YES in S427), the process returns to Step S421.
[0 1261
When the timer expires (YES in S429), the control unit 153 notifies a
30 neighbor base station of the base station 100-1 that the use situation of the weight
sets by the base station 100-1 is changed by the predetermined degree or more
(S43 1). Then, the process returns to Step S421.
[0 1 271
(Case of second example of weight-use-related condition)
Next, a process related to a case in which a second example of the weight-
5 use-related condition is applied will be described. The second example of the
weight-use-related condition is a condition that a use frequency of the weight sets for
beamforming by the base station be equal to or greater than a predetermined
frequency.
[0128]
10 (a) Cell selection process
FIG. 12 is a flowchart illustrating a second example of a schematic flow of a
cell selection process according to the first embodiment.
[0 1291
The control unit 153 determines whether a use frequency of weight sets by a
15 base station (for example, the base station 100-1 or a neighbor base stationj is equal
to or greater than a predetermined frequency (S441).
[0130]
When the use frequency use situation is equal to or greater than the
predetermined frequency (YES in S441), the control unit 153 does not perform cell
20 selection for the terminal device 200-1 based on received quality information (S443).
Then, the process returns to Step S441.
[0131]
When the use frequency use situation is less than the predetermined
frequency (NO in S44 I), the information acquiring unit 15 1 acquires received quality
25 information indicating received quality of a reference signal in the terminal device
200-1 and the control unit 153 performs cell selection for the terminal device 200-1
based on the received quality information (S445). Then, the process returns to Step
S441.
[0132]
30 (b) Notification process
FIG. 13 is a flowchart illustrating a second example of a schematic flow of a
notification process according to the first embodiment.
[0133]
The control unit 153 determines whether a use fiequency of weight sets by
the base station 100-1 is equal to or greater than a predetermined frequency (S461).
5 [0134]
When the use frequency use situation is equal to or greater than the
predetermined frequency (YES in S461), the control unit 153 notifies a neighbor
base station of the base station 100-1 that the use frequency of the weight sets by the
base station 100-1 is equal to or greater than the predetermined frequency (S463).
10 Then, the process returns to Step S461.
[0135]
<<4. Second embodiment>>
Next, a second embodiment of the present disclosure will be described with
reference to FIG. 14.
15 101361
In the second embodiment, a terminal device 200-2 performs cell selection
for the terminal device 200-2 based on received quality information indicating
received quality of a reference signal in the terminal device 200-2. When
predetermined condition related to the use of weight sets for beamforming by the
20 base station is satisfied, the terminal device 200-2 does not perform the selection
based on the received quality information. That is, while a subject is the base
station 100-1 in the first embodiment, a subject is the terminal device 200-2 in the
second embodiment.
[0137]
25 Accordingly, for example, it is possible to select a cell that is more
preferable for the terminal device 200-2 in an environment in which beamforming is
perfornled.
[0138]
14.1. Configuration of terminal device>
30 First, an example of a configuration of the terminal device 200-2 according
to the second embodiment will be described with reference to FIG. 14. FIG. 14 is a
block diagram illuswating an example of a configuration of the terminal device 200-2
according to the second embodiment. As illustrated in FIG. 14, the terminal device
200-2 includes an antenna unit 210, a wireless com~nunication unit 220, a storage
unit 230 and a processing unit 240.
5 [0139]
(Antenna unit 2 10)
The antenna unit 210 emits a signal to be output by the wireless
communication unit 220 into space as radio waves. In addition, the antenna unit
210 converts spatial radio waves into a signal and outputs the signal to the wireless
10 communication unit 220.
[0 1401
(Wireless communication unit 220)
The wireless communication unit 220 transmits and receives signals. For
example, the wireless communication unit 220 receives a downlink signal from the
15 base station 100-2 and transmits an uplink signal to the base station 100-2.
[0141]
(Storage unit 230)
The storage unit 230 stores programs and data for operations of the terminal
device 200-2.
20 [0142]
(Processing unit 240)
The processing unit 240 provides various functions of the terminal device
200-2. The processing unit 240 includes an information acquiring unit 241 and a
control unit 243. Alternatively, the processing unit 240 may further include a
25 component other than these components. That is, the processing unit 240 may also
perform an operation other than operations of these components.
[O 1431
(Infol-nlation acquiring unit 241)
The information acquiring unit 241 acquires received quality information
30 indicating received quality of a reference signal in the terminal device 200-2.
[O 1441
(a) Received quality
For example, the received quality is RSRQ. That is, the received quality
information is information indicating RSRQ.
[0145]
5 For example, the reference signal is a reference signal that is transmitted in
a frequency band. The frequency band is, for example, a CC of carrier aggregation.
For example, the reference signal is a CRS.
[0146]
(b) Acquiring method
10 For example, the terminal device 200-2 (the processing unit 240) measures
the received quality and stores received quality information indicating the received
quality in the storage unit 230. The information acquiring unit 241 acquires the
received quality information from the storage unit 230 at any timing thereafter.
101471
15 (Control unit 243)
The control unit 243 performs cell selection for the terminal device 200-2
based on the received quality information. Specifically, in the second embodiment,
when the predetermined condition related to the use of the weight sets for
beamforming by the base station (that is, a weight-use-related condition) is satisfied,
20 the control unit 243 does not perform the selection based on the received quality
information.
101481
(a) Cell selection
For example, the selection is cell selection or cell reselection by the terminal
25 device 200-2. For example, when the terminal device 200-2 is in an idle state, the
control unit 243 performs ccll selection or cell reselection.
[0149]
(b) Weight-use-related condition
There is no difference in descriptions of the weight-use-related condition
30 bet\vcen the first embodiment and the second embodiment except learning about a
use situation of weight sets and learning about a use frequency of weight sets.
Therefore, redundant descripiions will be omitted here. Only learning about the usc
situation of the weight sets and learning about the use frequency of the weight sets in
the second embodiment will be described.
[0150]
5 (b-4) First example of weight-use-related condition (change of use situation of
weight sets)
As a first example, the weight-use-related condition is a condition that a use
situation of the weight sets for beamforming by the base station be changed by a
predetermined degree or more. That is, when the use situation of the weight sets by
10 the base station is changed by the predetermined degree or more, the control unit 243
does not perform the selection based on the received quality information.
[0151]
- Learning about use situation of weight sets
For example, the base station 100-2 notifies the terminal device 200-2 of
15 information about the use situation of the weight sets for beamforming by the base
station (the base station 100-2 or a neighbor base station of the base station 100-2).
The base station 100-2 may notify the terminal device 200-2 that the use situation is
changed by the predetermined degree or more or may notify the terminal device 200-
2 of the use situation itself (for example, a weight set to be used or a use frequency of
20 weight sets). Therefore, the control unit 243 can determine whether the weight-userelated
condition for the base station is satisfied.
[0152]
(b-5) Second example of weight-use-related condition (use frequency of weight sets)
As a second example, the weight-use-related condition is a condition that a
25 use frequency of the weight sets for beamforming by the base station be a
predetermined frequency or more. That is, when the use frequency of the weight
sets for beamforming by the base station is equal to or greater than the predetermined
frequency, the control unit 243 does not perform the selection based on the received
quality information.
30 [0153]
- Learning about use frequency of weight sets
For example, the base station 100-2 notifies thc ternlinal device 200-2 of
information about the use frequency of the weight sets for beamforming by the base
station (the base station 100-2 or a neighbor base station of the base station 100-2).
The base station 100-2 may notify the terminal device 200-2 that the use frequency is
5 changed by the predetermined degee or more or may notify the terminal device 200-
2 of the use frequency itself. Therefore, the control unit 243 can determine whether
the weight-use-related condition for the base station is satisfied.
[0154]
(c) Others (measurement reporting)
10 When the weight-use-related condition is satisfied, the control unit 243 may
not report the received quality information to the terminal device 200-2.
Accordingly, for example, radio resources may be saved since reporting of received
quality information having low reliability is suppressed.
[OX551
15 <4.2. Process flow>
There is no difference in descriptions of a cell selection process of the
terminal device 200-2 according to the second embodiment except a subject (that is,
except that the base station 100-1 is a subject in the first embodiment and the
terminal device 200-2 is a subject in the second embodiment) between the first
20 embodiment and the second embodiment. Therefore, redundant descriptions will be
omitted here. In the second embodiment, "the infortnation acquiring unit 151" is
replaced by "the information acquiring unit 241" and "the control unit 153" is
replaced by "the control unit 243 ."
[0156]
25 The second embodiment has been described above. The base station 100-2
according to the second embodiment may operate in the same manner as the base
station 100-1 according to the first embodiment.
[0157]
<<5. Third embodiment>>
30 Next, a third embodiment of the present disclosure will be described with
reference to FIG. 15 to FIG. 17.
[Ol58]
In the third embodiment, a base station 100-3 transmits a signal using one or
more weight sets for beamforming. Specifically, the base station 100-3 uses the one
or more weight sets to transmit a signal in limited radio resources.
5 [0159]
Accordingly, for example, it is possible to select a cell that is more
preferable for the terminal device 200-3 in an environment in which beamforming is
performed.
[0160]
10 15.1. Configuration of base station>
First, an example of a configuration of the base station 100-3 according to
the third embodiment will be described with reference to FIG. 15 and FIG. 16. FIG.
15 is a block diagram illustrating an example of a configuration of the base station
100-3 according to the third embodiment. As illustrated in FIG. 15, the base station
15 100-3 includes the antenna unit 110, the wireless communication unit 120, the
network communication unit 130, the storage unit 140 and a processing unit 160.
[0161]
There is no difference in descriptions of the antenna unit 110, the wireless
communication unit 120, the network communication unit 130 and the storage unit
20 140 between the first embodiment and the third embodiment except for different
reference numerals. Therefore, redundant descriptions will be omitted here, and
only the processing unit 160 will be described.
[0 1621
(Processing unit 160)
25 The processing unit 160 provides various functions of the base station 100-3.
The processing unit 160 includes an information acquiriug unit 161 and a control unit
163. The processing unit 160 may further include a component other than these
components. That is, the processing unit 160 may also perform an operation other
than operations of these components.
30 [O163]
(Information acquiring unit 16 1)
The information acquiring unit 161 acquires one or more weight sets for
beamforming.
[0 1641
For example, the beamforming is large-scale MIMO beamforlning. The
5 beamforming may also be referred to as massive MIMO beamforming or threedimensional
beamforming.
[0165]
For example, the one or more weight sets are stored in the storage unit 140.
The information acquiring unit 161 acquires the one or more weight sets from the
10 storage unit 140.
[OI 661
(Control unit 163)
The control unit 163 controls wireless communication by the base station
100-3 such that the base station 100-3 transmits a signal using the one or more
15 weight sets. Specifically, in the third embodiment, the control unit 163 controls the
wireless communication such that the one or more weight sets are used to transmit a
signal in limited radio resources.
[0167]
(a) Specific process
20 For example, the control unit 163 controls the wireless comnunication by
multiplying a signal by the one or more weight sets.
[0168]
More specifically, for example, the control unit 163 multiplies a signal
transmitted in the limited radio resources by the one or more weight sets and does not
25 multiply a signal transmitted in other radio resources by the one or more weight sets.
[0169]
(b) Limited radio resources
(b-1) First example
As a first example, the limited radio resources are radio resources of a
30 predetern~ineda mount or a predetermined ratio or less. That is, the control unit 163
controls the wireless cominunication such that the one or more weight sets are used
to transmit a signal in radio resources of the predetermined amount or thc
predetermined ratio or less. 111 other words, the control unit 163 controls the
wireless communication such that the one or more weight sets are used at a
predetermined frequency or less.
5 [0170]
For example, the limited radio resources are radio resources of the
predetermined amount or the predetermined ratio or less among radio resources of
frequency bands. More specifically, for example, the limited radio resources are
resource blocks of a predetermined amount or a predetermined ratio or less among
10 resource blocks of a component carrier (CC). That is, the control unit 163 controls
the wireless communication such that the one or more weight sets are used to
transmit a signal in resource blocks of the predetermined amount or the
predetermined ratio or less among resource blocks of CCs.
[0171]
15 As an example, the limited radio resources are resource blocks of a
predetermined amount or a predetermined ratio or less among resource blocks
arranged in a frequency direction across a CC. As a specific example, the limited
radio resources are 20 resource blocks or less (20% resource blocks or less) among
100 resource blocks arranged in the frequency direction across a CC of 20 MHz.
20 [0172]
As another example, the limited radio resources may be resource blocks of a
predetermined amount or a predetermined ratio or less among resource blocks for
each predetermined period of a CC. Specifically, the limited radio resources may
be 40 resource blocks or less (20% resource blocks or less) among 200 resource
25 blocks for each subframe of the CC of 20 MHz. Alternatively, the limited radio
resources may be 400 resource blocks or less (20% resource blocks or less) among
2000 resource blocks for each radio frame (that is, 10 subframes) for the CC of 20
MHz.
[0173]
30 Accordingly, for example, an amount of beains emitted by the base station
100-3 is suppressed. As a result, a variation of received quality (for exai~~ple,
RSRQ) in the terminal device 200-3 is reduced. As a result, a decrease in reliability
of the received quality information is suppressed. Therefore, a cell that is more
preferable for the terminal device 200-3 may be selected.
[O 1 741
5 (b-2) Second example
As a second example, the limited radio resources are radio resources of
some bands among frequency bands, and the some bands are bands other than a
predetermined band among the frequency bands. That is, the control unit 163
controls the wireless communication such that the one or more weight sets are used
10 to transmit a signal in radio resources of some bands (bands other than the
predetermined band) among frequency bands.
[0175]
More specifically, for example, the limited radio resources are radio
resources of some bands (bands other than the predetermined band) among
15 component carriers (CCs). That is, the control unit 163 controls the wireless
communication such that the one or more weight sets are used to transmit a signal in
radio resources of some bands (bands other than the predetermined band) among the
CCs. Hereinafter, this will be described with reference to a specific example of FIG.
16.
20 [0176]
FIG 16 is an explanatory diagram for describing an example of
beamforming in some bands. Referring to FIG. 16, radio resources of a CC 61 are
shown. The CC 61 includes a band 63 and a band 65. That is, the band 63 is a
part of a band within a CC 57 and is a band other than the band 65. For example,
25 one or more weight sets are used to transmit a signal in (a part of or all of) a radio
resource 67 of the band 63 within the CC 61. On the other hand, none of the weight
sets are used to transmit a signal in a radio resource 69 of the band 65 within the CC
61. Accordingly, beamforming is performed in the band 63 but beamforming is not
performed in the band 65. In this example, the predetermined band 65 is a band of
30 a predetermined width at a center of the CC 61. The predetermined width is a width
that cor~espondlso , for example, 6 resource blocks.
[0 1 771
Accordingly, for example, since no influence of a beam is received in in the
predetermined band, a received signal strength (for example, RSSI) in the
predetermined band does not significantly vary. Therefore, for example, stable
5 received quality (for example, RSRQ) is calculated based on the received signal
strength. That is, a decrease in reliability of received quality information is
suppressed. Therefore, a cell that is more preferable for the terminal device 200-3
may be selected.
[0178]
10 The control unit 163 notifies the terminal device 200-3 of the predetermined
band. Accordingly, for example, the terminal device 200-3 can measure a received
signal strength in the predetermined band.
[0 1791
(b-3) Others
15 For example, the limited radio resources include radio resources of symbols
in which physical downlink shared channels are arranged but do not include radio
resources of symbols in which physical downlink control channels (PDCCHs) are
arranged. As an example, the limited radio resources include radio resources of 4th
to 14th symbols but do not include radio resources of 1st to 3rd symbols among
20 subframes including 14 symbols.
[Ol 801
<5.2. Process flow>
Next, an example of a process according to the third embodiment will be
described with reference to FIG. 17. FIG. 17 is a flowchart illustrating an example
25 of a schematic flow of a process according to the third embodiment.
[0181]
The information acquiring unit 161 acquires one or more weight sets for
beamfornling (S50 1).
[0 1 821
30 Then, the base station 100-3 transmits a signal using the one or more weight
sets in limited radio resources under control of ihe control unit 163 (S503). The
base station 100-3 transmits the signal without using the one or inore weight sets in
other wireless references under control of the control unit 163. Then, the process
returns to Step S501.
[0 1831
5 The third embodiment has been described above. The third embodiment
may be combined with the first embodiment. For example, the base station 100-1
according to the first embodiment may operate in the same manner as the base
station 100-3 according to the third embodiment. More specifically, for example,
the control unit 153 according to the first embodiment may control wireless
10 communication by the base station 100-1 in the same manner as in the control of
wireless communication of the base station 100-3 by the control unit 163 according
to the third embodiment.
[0 1 841
<<6. Application examples>>
15 The technology according to the present disclosure is applicable to a variety
of products. The base station 100 may also be implemented, for example, as any
type of evolved Node B (eNB) such as macro eNBs and small eNBs. Small eNBs
may cover smaller cells than the macrocells of pico eNBs, micro eNBs, or home
(femt) eNBs. Instead, the base station 100 may be implemented as another type of
20 base station such as Nodes B or base transceiver stations (BTSs). The base station
100 may include the main apparatus (which is also referred to as base station
apparatus) that controls wireless communication and one or more remote radio heads
(RRHs) that are disposed at different locations from that of the main apparatus.
Furthel; various types of terminals as will be discussed later may temporarily or
25 semi-persistently execute the base station function to operate as the base station 100.
Further, at least part of components of the base station 100 may be implemented in a
base station device or a module for the base station device.
[0185]
The terminal device 200 may be implemented as a mobile terminal such as
30 smartphones, tablet personal computers (PCs), notebook PCs, portable game
terminals, portable/dongle mobile routers, and digital cameras, or an in-vehicle
terminal such as car navigation apparatuses. The terminal device 200 may also be
implemented as a terminal (which is also referred to as n~achinety pe communication
(MTC) terminal) that performs machine to machine (M2M) communication.
Furthermore, at least part of components of the terminal device 200 may be
6 implemented as a module (e.g. integrated circuit module constituted with a single
die) that is mounted on these terminals.
[0186]
16.1. Application examples for base station>
(First application example)
10 FIG. 18 is a block diagram illustrating a first example of a schematic
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
apparatus 820. Each antenna 810 and the base station apparatus 820 may be
connected to each other via an RF cable.
15 [0187]
Each of the antennas 810 includes a single or a plurality of antenna elements
(e.g. a plurality of antenna elements constituting a MIMO antenna) and is used for
the base station apparatus 820 to transmit and receive a wireless signal. The eNB
800 may include the plurality of the antennas 810 as illustrated in FIG. 18, and the
20 plurality of antennas 810 may, for example, correspond to a plurality of frequency
hands used by the eNB 800. It should be noted that while FIG. 18 illustrates an
example in which the eNB 800 includes the plurality of antennas 810, the eNB 800
may include the single antenna 810.
[0188]
25 The base station apparatus 820 includes a controller 821, a memory 822, a
network interface 823, and a wireless communication interface 825.
[O 1891
The controller 821 may be, for example, a CPU or a DSP, and operates
various functions of an upper layer of the base station apparatus 820. For example,
30 the controller 821 generates a data packet from data in a signal processed by the
wireless communication interface 825, and transfers the generated packet via the
network interface 823. The controller 821 may generate a bundled packet by
bundling data from a plurality of base band processors to transfer the generated
bundled packet. The controller 821 may also have a logical function of performing
control such as radio resource control, radio bearer control, mobility management,
5 admission control, and scheduling. The control may be performed in cooperation
with a surrounding eNB or a core network. The memory 822 includes a RAM and a
ROM, and stores a program executed by the controller 821 and a variety of control
data (such as, for example, terminal list, transmission power data, and scheduling
data).
10 [0190]
The network interface 823 is a communication interface for connecting the
base station apparatus 820 to the core network 824. The controller 821 may
communicate with a core network node or another eNB via the network interface 823.
In this case, the controller 821 may be mutually connected to the eNB 800 and a core
15 network node or another eNB through a logical interface (e.g. S1 interface or X2
interface). The network interface 823 may be a wired communication interface or a
wireless communication interface for wireless backhaul. When the network
interface 823 is a wireless communication interface, the network interface 823 may
use a higher frequency band for wireless coinmunication than a frequency band used
20 by the wileless communication interface 825.
[0191]
The wireless communication interface 825 supports a cellular
communication system such as long term evolution (LTE) or LTE-Advanced, and
provides wireless connection to a terminal located within the cell of the eNB 800 via
25 the antenna 810. The wireless communication interface 825 may typically include a
base band (BB) processor 826 and an RF circuit 827. The BB processor 826 may,
for example, perform encoding/decoding, modulation/den~odulation,
multiplexing/demultiplexing, and the like, and performs a variety of signal
processing on each layer (e.g. L1, mediuin access control (MAC), radio link control
30 (RLC), and packet data convergence protocol (PDCP)). The BB processor 826 may
have part or all of the logical functions as discussed above instead of the contloller
821. The BB processor 826 may be a module including a niemory having a
communication control program stored therein, a processor to execute the program,
and a related circuit, and the function of the BB processor 826 may be changeable by
updating the program. The module may be a card or blade to be inserted into a slot
5 of the base station apparatus 820, or a chip mounted on the card or the blade.
Meanwhile, the RF circuit 827 may include a mixer, a filtel; an amplifier, and the like,
and transmits and receives a wireless signal via the antenna 810.
[0 1 921
The wireless communication interface 825 may include a plurality of the BB
10 processors 826 as illustrated in FIG. 18, and the plurality of BB processors 826 may,
for example, correspond to a plurality of frequency bands used by the eNB 800.
The wireless communication interface 825 may also include a plurality of the RF
circuits 827, as illustrated in FIG. 18, and the plurality of RF circuits 827 may, for
example, correspond to a plurality of antenna elements. FIG. 18 illustrates an
15 example in which the wireless communication interface 825 includes the plurality of
BB processors 826 and the plurality of RF circuits 827, but the wireless
communication interface 825 may include the single BB processor 826 or the single
RF circuit 827.
[0193]
20 In the eNB 800 illustrated in FIG. 18, the information acquiring unit 15 1 and
the control unit 153 described above with reference to FIG. 6 may be mounted in the
wireless communication interface 825. Alternatively, at least some of the
components may be mounted in the controller 821. As an example, the eNB 800
may be equipped with a module including some or all components of the wireless
25 communication interface 825 (for example, the BB processor 826) and/or the
controller 821, and the information acquiring unit 15 1 and the control unit 153 above
may be mounted in the module. In this case, the module may store a program
causing the processor to function as the information acquiring unit 151 and the
control unit 153 above (that is, a program causing the processor to perform the
30 operation of the information acquiring unit 151 and the control unit 153 above) and
execute the program. As another example, the prograin causing the processor to
function as tlie information acquiring unit 15 1 and the control unit 153 above niay be
installed in the eNB 800, and the wireless communication interface 825 (for exarnplc,
the BB processor 826) and/or tlie controller 821 may execute the program. As
described above, the eNB 800, the base station apparatus 820, or the module may be
5 provided as an apparatus including the information acquiring unit 15 1 and the control
unit 153 above, and the program causing the processor to function as the information
acquiring unit 151 and the control unit 153 above may be provided. A readable
recording medium in which the program is recorded may be provided. For these
points, the information acquiring unit 161 and the control unit 163 described above
10 with reference to FIG. 15 are the same as the information acquiring unit 15 1 and the
control unit 153.
[O 1941
In the eNB 800 illustrated in FIG. 18, the wireless communication unit 120
described above with reference to FIG. 6 may be mounted in the wireless
15 communication interface 825 (for example, the RF circuit 827). The antenna unit
110 may be mounted in the antenna 810. The network communication unit 130
may be mounted in the controller 821 and/or the network interface 823.
[0195]
(Second application example)
20 FIG. 19 is a block diagram illustrating a secoiid 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
apparatus 850, and an RRH 860. Each of the antennas 840 and the RRH 860 may
be connected to each other via an RF cable. The base station apparatus 850 and the
25 RRH 860 niay be co~lnectedt o each other by a high speed line such as optical fiber
cables.
[0196]
Each of the antennas 840 includes a single or a plurality of antenna elenie~its
(e.g. autelina elements constituting a MIMO antenna), and is used for the RRI-I 860
30 to transmit and receive a wireless signal. The eNB 830 may include a plwality of
the antemias 840 as illustrated in FIG. 19, and the plurality of antennas 840 may, for
example, correspond to a plurality of frequency bands used by the eNB 830. FIG.
19 illustrates an example in which the eNB 830 includes the plurality of anteilnas
840, but the eNB 830 may include the single antenna 840.
[O 1 971
6 The base station apparatus 850 includes a controller 851, a memory 852, a
network interface 853, a wireless communication interface 855, and a connection
interface 857. The controller 851, the memory 852, and the network interface 853
are the same as the controller 821, the memory 822, and the network interface 823
described with reference to FIG. 18.
10 [0198]
The wireless communication interface 855 supports a cellular
communication system such as LTE and LTE-Advanced, and provides wireless
connection to a terminal located in a sector corresponding to the RRH 860 via the
RRH 860 and the antenna 840. The wireless communication interface 855 may
15 typically include a BB processor 856. The BB processor 856 is the same as the BB
processor 826 described with reference to FIG. 18 except that the BB processor 856
is connected to an RF circuit 864 of the RRH 860 via the connection interface 857.
The wireless communication interface 855 may include a plurality of the BB
processors 856, as illustrated in FIG. 19, and the plurality of BB processors 856 may,
20 for example, correspond to a plurality of frequency bands used by the eNB 830
respectively. FIG. 19 illustrates an example in which the wireless communication
interface 855 includes the plurality of BB processors 856, but the wireless
communication interface 855 may include the single BB processor 856.
[0199]
25 The connection interface 857 is an interface for connecting the base station
apparatus 850 (wireless communication interface 855) to the RRH 860. The
connection interface 857 may be a communication module for communication on the
high speed line which connects the base station apparatus 850 (wireless
communication interface 855) to the RRH 860.
30 [0200]
The RRH 860 includes a connection interface 861 and a wireless
communication interface 863.
[0201]
The connection interface 861 is an interface for connecting the RRH 860
(wireless communication interface 863) to the base station apparatus 850. The
5 connection interface 861 may be a conmunication module for communication on the
high speed line.
[0202]
The wireless communication interface 863 transmits and receives a wireless
signal via the antenna 840. The wireless communication interface 863 may
10 typically include the RF circuit 864. The RF circuit 864 may include a mixer, a
filter, an amplifier and the like, and transmits and receives a wireless signal via the
antenna 840. The wireless communication interface 863 may include a plurality of
the RF circuits 864 as illustrated in FIG. 19, and the plurality of RF circuits 864 may,
for example, correspond to a plurality of antenna elements. FIG. 19 illustrates an
15 example in which the wireless communication interface 863 includes the plurality of
RF circuits 864, but the wireless communication interface 863 may include the single
RF circuit 864.
[0203]
In the eNB 830 illustrated in FIG. 19, the information acquiring unit 15 1 and
20 the control unit 153 described above with reference to FIG. 6 may be mounted in the
wireless communication interface 855 and/or the wireless communication interface
863. Alternatively, at least some of the components may be mounted in the
controller 851. As an example, the eNB 830 may be equipped with a module
including some or all components of the wireless communication interface 855 (for
25 example, the BB processor 856) and/or the controller 851, and the infoimation
acquiring unit 151 and the control unit 153 above may be mounted in the module.
In this case, the module may store a program causing the processor to function as the
information acquiring unit 151 and the control unit 153 above (that is, a program
causing the processor to perforni the operation of the information acquiring unit 151
30 and the control unit 153 above) and execute the program. As another example, the
program causing the processor to function as the information acquiring unit 151 and
the control unil 153 above may be installed in the eNB 830, and the wireless
cominunication interface 855 (for example, the BB processor 856) andlor the
controller 851 may execute the program. As described above, the eNB 830, the
base station apparatus 850, or the module may be provided as an apparatus including
5 the information acquiring unit 15 1 and the control unit 153 above, and the program
causing the processor to function as the information acquiring unit 151 and the
control unit 153 above may be provided. A readable recording medium in which
the program is recorded may be provided. For these points, the information
acquiring unit 161 and the control unit 163 described above with reference to FIG. 15
10 are the same as the information acquiring unit 151 and the control unit 153.
[0204]
In the eNB 830 illustrated in FIG. 19, the wireless communication unit 120
described above with reference to FIG. 6 may be mounted in the wireless
communication interface 863 (for example, the RF circuit 864). The antenna unit
15 110 may be mounted in the antenna 840. The network communication unit 130
may be mounted in the controller 851 andlor the network interface 853.
[0205]
16.2. Application examples for terminal device>
(First application example)
20 FIG. 20 is a block diagram illustrating an example of a schematic
configuration of a smartphone 900 to which the technology according to the present
disclosure may be applied. The smartphone 900 includes a processor 901, a
memory 902, a 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
25 9 11, a wireless communication interface 912, one or more antenna switches 91 5, one
or more antennas 916, a bus 917, a battery 918, and a secondary controller 919.
[0206]
The processor 901 may be, for example, a CPU or a system on chip (SoC),
and controls the functions of an application layer and other layers of the smartphone
30 900. The inemory 902 includes a RAM and a ROM, and stores a program executed
by the proccssor 901 and data. The storage 903 may include a storage medium such
as semiconductor memories and hard disks. Thc cxternal counection inte~face9 04
is an interface for connecting the smartphone 900 to an externally attached device
such as memory cards and universal serial bus (USB) devices.
[0207]
5 The camera 906 includes an image sensor such as charge coupled devices
(CCDs) and complementary metal oxide semiconductor (CMOS), and generates a
captured image. The sensor 907 may include a sensor group including, for example,
a positioning sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor.
The microphone 908 converts a sound that is input into the smartphone 900 to an
10 audio signal. The input device 909 includes, for example, a touch sensor which
detects that a screen of the display device 910 is touched, a key pad, a keyboard, a
button, or a switch, and accepts an operation or an information input from a user.
The display device 910 includes a screen such as liquid crystal displays (LCDs) and
organic light emitting diode (OLED) displays, and displays an output image of the
15 smartphone 900. The speaker 911 converts the audio signal that is output from the
smartphone 900 to a sound.
[0208]
The wireless communication interface 912 supports a cellular
communication system such as LTE or LTE-Advanced, and performs wireless
20 communication. The wireless co~lununication interface 912 may typically include
the BB processor 913, the RF circuit 914, and the like. The BB processor 913 may,
for example, perform encodingldecoding, modulation/demodulation,
multiplexingldemultiplexing, and the like, and performs a variety of types of signal
processing for wireless communication. On the other hand, the RF circuit 914 may
25 include a mixer, a filter, an amplifier, and the like, and transmits and receives a
wireless signal via the antenna 91 6. The wireless comn~unicationi nterface 912 may
be a one-chip module in which the BB processor 913 and the RF circuit 914 are
integrated. The wireless comnlumication interface 912 may include a plurality of
BB processors 913 and a plurality of RF circuits 914 as illustrated in FIG. 20. FIG.
30 20 illustrates an example in which the wireless conununication interface 912 includes
a plurality of BB processors 913 and a plurality of RF circuits 914, but the wireless
communication interface 912 may include a single BB processor 913 or a single RF
circuit 914.
[0209]
Further, the wireless communication interface 912 may support other types
6 of wireless coinmunication system such as a short range wireless communication
system, a near field communication system, and a wireless local area network (LAN)
system in addition to the cellular communication system, and in this case, the
wireless communication interface 912 may include the BB processor 913 and the RF
circuit 914 for each wireless communication system.
10 [0210]
Each antenna switch 915 switches a connection destination of the antenna
916 among a plurality of circuits (for example, circuits for different wireless
communication systems) included in the wireless communication interface 912.
[0211]
15 Each of the antennas 916 includes one or more antenna elements (for
example, a plurality of antenna elements constituting a MIMO antenna) and is used
for transmission and reception of the wireless signal by the wireless communication
interface 912. The smartphone 900 may include a plurality of antennas 916 as
illustrated in FIG. 20. FIG. 20 illustrates an example in which the smartphone 900
20 includes a plurality of antennas 91% but the smartphone 900 may include a single
antenna 916.
[02 121
Further, the smartphone 900 may include the antenna 916 for each wireless
communication system. In this case, the antenna switch 915 may be omitted from a
25 configuration of the smartphone 900.
[0213]
The bus 917 connects the processor 901, the memory 902, the storage 903,
the external connection interface 904, the camera 906, the sensor 907, the
microphone 908, the input device 909, the display device 910, the speaker 911, the
30 wireless con~municationin terface 912, and the secondary controller 919 to each other.
The battery 918 supplies electric power to each block of the smartphone 900
illustrated in FIG. 20 via a feeder line that is partially illustrated in the figure as a
dashed line. The secondary controller 919, for example, operates a minimally
necessary function of the smartphone 900 in a sleep mode.
[02 141
5 In the smartphone 900 illustrated in FIG. 20, the information acquiring unit
241 and the control unit 243 described above with reference to FIG. 14 may be
mounted in the wireless communication interface 912. Alteinatively, at least some
of the components may be mounted in the processor 901 or the secondary controller
919. As an example, the smartphone 900 may he equipped with a module including
10 some or all components of the wireless communication interface 912 (for example,
the BB processor 913), the processor 901, andlor the secondary controller 919, and
the information acquiring unit 241 and the control unit 243 above may be mounted in
the module. In this case, the module may store a program causing the processor to
function as the infoimation acquiring unit 241 and the control unit 243 above (that is,
15 a program causing the processor to perform the operation of the information
acquiring unit 241 and the control unit 243 above) and execute the program. As
another example, the program causing the processor to function as the information
acquiring unit 241 and the control unit 243 above may be installed in the smartphone
900, and the wireless communication interface 912 (for example, the BB processor
20 913), the processor 901, and/or the secondary controller 919 may execute the
program. As described above, the smartphone 900 or the module may be provided
as an apparatus including the information acquiring unit 241 and the control unit 243
above, and the program causing the processor to function as the information
acquiring unit 241 and the control unit 243 above may be provided. A readable
26 recording medium in which the program is recorded may be provided.
[02 151
In the smartphone 900 illustrated in FIG. 20, for example, the wireless
communication unit 220 described above with reference to FIG. 14 may be mounted
in the wireless communication interface 912 (for exanlple, the RF circuit 914). The
30 antenna unit 210 may be mounted in the antenna 916.
[02 161
(Second application example)
FIG. 21 is a block diagram illustrating an example of a schematic
configuralion of a car navigation apparatus 920 to which the technology according to
the present disclosure may be applied. The car navigation apparatus 920 includes a
5 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 wireless
communication interface 933, one or more antenna switches 936, one or more
antennas 937, and a battery 938.
10 [0217]
The processor 921 may be, for example, a CPU or an SoC, and controls the
navigation function and the other functions of the car navigation apparatus 920.
The memory 922 includes a RAM and a ROM, and stores a program executed by the
processor 921 and data.
15 [0218]
The GPS module 924 uses a GPS signal received from a GPS satellite to
measure the position (e.g. latitude, longitude, and altitude) of the car navigation
apparatus 920. The sensor 925 may include a sensor group including, for example,
a gyro sensor, a geomagnetic sensor, and an air pressure sensor. The data interface
20 926 is, for example, connected to an in-vehicle network 941 via a terminal that is not
illustrated, and acquires data such as vehicle speed data generated on the vehicle side.
[02 191
The content player 927 reproduces content stored in a storage medium (e.g.
CD or DVD) inserted into the storage medium interface 928. The input device 929
25 includes, for example, a touch sensor which detects that a screen of the display
device 930 is touched, a button, or a switch, and accepts operation or information
input from a user. The display device 930 includes a screen such as LCDs and
OLED displays, and displays an image of the navigation function or the reproduced
content. The speaker 931 outputs a sound of the navigation function or the
30 reproduced content.
[0220]
The wireless communication interface 933 supports a cellular
communication system such as LTE or LTE-Advanced, and performs wireless
communication. The wireless communication interface 933 ]nay typically include
the BB processor 934, the RF circuit 935, and the like. The BB processor 934 may,
5 for example, perfor111 encodingldecoding, modulation/demodulation,
n~ultiplexingldemultiplexing, and the like, and performs a variety of types of signal
processing for wireless communication. On the other hand, the RF circuit 935 may
include a mixer, a filter, an amplifier, and the like, and transmits and receives a
wireless signal via the antenna 937. The wireless communication interface 933 may
10 be a one-chip module in which the BB processor 934 and the RF circuit 935 are
integrated. The wireless communication interface 933 may include a plurality of
BB processors 934 and a plurality of RF circuits 935 as illustrated in FIG. 21. FIG.
21 illustrates an example in which the wireless communication interface 933 includes
a plurality of BB processors 934 and a plurality of RF circuits 935, but the wireless
15 communication interface 933 may be a single BB processor 934 or a single RF
circuit 935.
[0221]
Fu-ther, the wireless communication interface 933 may support other types
of wireless communication system such as a short range wireless communication
20 system, a near field communication system, and a wireless LAN system in addition
to the cellular communication system, and in this case, the wireless communication
interface 933 may include the BB processor 934 and the RF circuit 935 for each
wireless communication system.
[0222]
25 Each antenna switch 936 switches a connection destination of the antenna
937 among a plurality of circuits (for example, circuits for different wireless
communication systems) included in the wireless communication interface 933.
[0223]
Each of the antennas 937 includes one or morc antenna elements (for
30 example, a plurality of antenna elements constituting a MIMO antenna) and is used
for transmission and reception of the wireless signal by the wireless communication
interface 933. The car navigation apparatus 920 includes a plurality of antennas
937 as illustrated in FIG. 21. FIG. 21 illustrates an example in which the car
navigation apparatus 920 includes a plurality of antennas 937, but the car navigation
apparatus 920 may include a single antenna 937.
5 [0224]
Further, the smartphone 920 may include the antenna 937 for each wireless
communication system. In this case, the antenna switch 936 may be omitted from a
configuration of the car navigation apparatus 920.
[0225]
10 The battery 950 supplies electric power to each block of the car navigation
apparatus 930 illustrated in FIG. 21 via a feeder line that is partially illustrated in the
figure as a dashed line. The battery 950 accumulates the electric power supplied
from the vehicle.
[0226]
15 In the car navigation apparatus 920 illustrated in FIG. 21, the information
acquiring unit 241 and the control unit 243 included in the processing unit 240
described above with reference to FIG. 14 may be mounted in the wireless
communication interface 933. Alternatively, at least some of the components may
be mounted in the processor 921. As an example, the car navigation apparatus 920
20 may be equipped with a module including some or all components of the wireless
communication interface 933 (for example, the BB processor 934) and/or the
processor 921, and the information acquiring unit 241 and the control unit 243 above
may be mounted in the module. hi this case, the module may store a program
causing the processor to function as the information acquiring unit 241 and the
25 control unit 243 above (that is, a program causing the processor to perform the
operation of the information acquiring unit 241 and the control unit 243 above) and
execute the program. As another example, the program causing the processor to
function as the information acquiring unit 241 and the control unit 243 above may be
installed in the car navigation apparatus 920, and the wireless comnlunication
30 interface 933 (for example, the BB processor 934) and/or the processor 921 may
execute the program. As described above, the car navigation apparatus 920, the
base station apparatus 850, or the module may be provided as an apparatus including
the information acquiring unit 241 and the control unit 243 above, and the program
causing the processor to function as the information acquiring unit 241 and the
control unit 243 above may be provided. A readable recording medium in which
5 the program is recorded may be provided.
[0227]
In the car navigation apparatus 920 illustrated in FIG. 21, for example, the
wireless communication unit 220 described above with reference to FIG. 14 may be
mounted in the wireless communication interface 933 (for example, the RF circuit
10 935). The antenna unit 210 may be mounted in the antenna 937.
[0228]
Further, the technique according to the present disclosure may be
implemented as an in-vehicle system (or a vehicle) 940 including one or more blocks
of the above-described car navigation apparatus 920, an in-vehicle network 941 and a
15 vehicle side module 942. That is, the in-vehicle system (or the vehicle) 940 may be
provided as an apparatus including the information acquiring unit 241 and the control
unit 243. The vehicle side module 942 generates vehicle side data such as vehicle
speed, engine speed and failure information and outputs the generated data to the invehicle
network 961.
20 [0229]
<<7. Conclusion>>
The device and the processes according to the embodiments of the present
disclosure have been described so far with reference to FIG. 3 to FIG. 21.
LO2301
25 (First embodiment)
According to the first embodiment, the base station 100-1 includes the
information acquiring unit 151 configured to acquire received quality information
indicating received quality of a reference signal in the terminal device 200-1 and the
control unit 153 configured to perform cell selection for the terminal device 200-1
30 based on the received quality information. When predetermined condition related
to use of weight sets for beamforming by the base station is satisfied, the control unit
153 does not perform the selection based on the received quality information.
[023 11
(Second embodiment)
According to the second embodiment, the terminal device 200-2 includes
5 the information acquiring unit 241 configured to acquire received quality information
indicating received quality of a reference signal in the terminal device 200-2 and the
control unit 243 configured to perform cell selection for the terminal device 200-2
based on the received quality information. When a predetermined condition related
to use of weight sets for beamforming by the base station is satisfied, the control unit
10 243 does not perform the selection based on the received quality information.
[0232]
(Third embodiment)
According to the third embodiment, the base station 100-3 includes the
information acquiring unit 161 confignred to acquire one or more weight sets for
15 beamforming and the control unit 163 configured to control wireless communication
by the base station 100-3 such that the base station 100-3 transmits a signal using the
one or more weight sets. The control unit 163 controls the wireless communication
such that the one or more weight sets are used to transmit a signal in limited radio
resources.
20 [0233]
According to the first to third embodiments, for example, it is possible to
select a cell that is more preferable for a terminal device in an environment in which
beamforming is performed.
[0234]
25 The preferred embodiment of the present disclosure has been described
above with reference to the accompanying drawings, whilst the present disclosure is
not limited to the above examples. A person skilled in the art may find various
alterations and modifications within the scope of the appended claims, and it should
be understood that they will naturally come under the technical scope of the present
30 disclosure.
[0235]
For exanlple, while an example in which a communication system supports,
for example, LTE, LTE-Advanced or a communication standard equivalent thereto
has been described, the present disclosure is not limited thereto. For example, the
communication system may be a system that supports another communication
5 standard.
[0236]
Further, it is not always necessary to execute the processing steps in the
processing in the present specification in chronological order in order described in
the flowcharts or the sequence diagrams. For example, the processing steps in the
10 above-described processing may be executed in order different from the order
described in the flowcharts or the sequence diagrams or may be executed in parallel.
[0237]
Further, it is also possible to create a computer program for making a
processor (such as, for example, a CPU and a DSP) provided at apparatuses (such as,
15 for example, the base station, the base station device for the base station or the
module of the base station device, or the terminal device or the module for the
terminal device) in the present specification function as the above-described
apparatuses (in other words, a computer program for making the processor execute
operation of the components of the above-described apparatuses). Further, it is also
20 possible to provide a recording medium having the above-described computer
program recorded therein. Further, it is also possible to provide an apparatus (such
as, for example, a fmished product and a module (such as pats, processing circuits
and chips) for the finished product) including a memory having the above-described
computer program stored therein and one or more processors which can execute the
25 above-described computer program. Further, a method including the operation of
the components (for example, an information acquiring unit and the control unit) of
the above-described apparatuses is included in the technique according to the present
disclosure.
[0238]
30 In addition, the effects described in the present specification are merely
illustrative and demonstrative, and not limitative. h other words, the technology
according to the present disclosure can exhibit othcr effects that are evident to those
skilled in the art along with or instead of the effects based on the present
specification.
[0239]
5 Additionally, the present technology may also be configured as below.
(1)
A device including:
an acquiring unit configured to acquire received quality information
indicating received quality of a reference signal in a terminal device; and
10 a control unit configured to perform cell selection for the terminal device
based on the received quality information,
wherein, when a predetermined condition related to use of weight sets for
beamforming by a base station is satisfied, the control unit does not perform the
selection based on the received quality information.
15 (2)
The device according to (I),
wherein the predetermined condition is a condition that a use situation of the
weight sets for beamforming by the base station be changed by a predetermined
degree or more.
20 (3)
The device according to (2),
wherein the predetermined condition is a condition that a weight set for
beamforming used by the base station be changed by a predeteinlined degree or more.
(4)
25 The device according to (2),
wherein the predetermined condition is a condition that a use frequency of
the weight sets for beamforming by the base station be changed by a predetermined
degree or more.
(5)
30 The device according to any one of (2) to (4),
wherein the control unit does not perform the selection based on the
received quality information for a predetermined period after the predetermined
condition is satisfied.
(6)
The device according to (I),
wherein the predetermined condition is a condition that a use frequency of
the weight sets for beamforming by the base station be equal to or greater than a
predetermined frequency.
(7)
The device according to (4) or (6),
wherein the use frequency is an amount or a ratio of radio resources through
which the base station transmits a signal using a weight set for beamforming, and
the predetermined frequency is a predetermined amount or ratio.
(8)
The device according to any one of (1) to (7),
15 wherein the reference signal is a reference signal that is transmitted in a
frequency band, and
the predetermined condition is a condition related to the use of the weight
sets for beamforming by the base station in the frequency band.
(9)
20 The device according to any one of (I) to (8),
wherein the base station is a base station to which the terminal device is
connected or a neighbor base station of the base station to which the terminal device
is connected.
(10)
25 The device according to any one of (1) to (9),
wherein the device is a base station to which the terminal device is
connected, a base station device for the base station, or a module for the base station
device,
the received quality information is information that is reported by the
30 terminal device to the base station to which the terminal device is connected, and
a cell is a target cell of a bandover of the terminal device or a secondary cell
of carrier aggregation for the tcrminal device.
(11)
The device according to any one of (1) to (9),
wherein the device is the terminal device or a module for the terminal
5 device, and
the selection is cell selection or cell reselection by the tem~inadl evice.
(12)
The device according to (lo),
wherein the control unit controls wireless communication by the base
10 station to which the terminal device is connected such that the base station to which
the terminal device is connected transmits a signal using one or more weight sets for
beamforming, and
the control unit controls the wireless communication such that the one or
more weight sets are used to transmit a signal in limited radio resources.
15 (13)
A method including:
acquiring received quality information indicating received quality of a
reference signal in a terminal device; and
performing, by a processor, cell selection for the terminal device based on
20 the received quality information,
wherein, when a predetermined condition related to use of weight sets for
beamforming by a base station is satisfied, the selection is not performed based on
the received quality information.
(14)
A device including:
an acquiring unit configured to acquire one or more weight sets for
bearnfornling; and
a control unit configured to control wireless coinmunication by a base
station such that the base station transmits a signal using the one or more weight sets,
30 wherein the control unit coi~trolst he wireless commui~ications uch that the
one or more weight sets are used to transinit a signal in limited radio resources.
(15)
The device according to (14),
wherein the limited radio resources are radio resources of a predetermined
amount or a predetermined ratio or less.
5 (16)
The device according to (14),
wherein the limited radio resources are radio resources of some bauds
among frequency bauds, and
the some bands are bands other than a predetermined band among the
10 frequency bands.
(17)
The device according to (16),
wherein the control unit notifies a terminal device of the predetermined
band.
15 (18)
The device according to any one of (14) to (17);
wherein the control unit multiplies a signal by the one or more weight sets
and thus controls the wireless communication.
(19)
20 The device according to any one of (1 4) to (1 8),
wherein the device is the base station, a base station device for the base
station, or a module for the base station device.
(20)
A method including:
25 acquiring one or more weight sets for beamforming; and
controlling, by a processor, wireless communication by a base station such
that the base station transmits a signal using the one or more weight sets,
wherein the controlling of the wireless con~n~unicatioinnc ludes controlling,
by the processor, the wireless comnlunication such that the one or more weight sets
30 are used to transmit a signal in limited radio resources.
(21)
Aprograrn [or causing a processor to function as:
an acquiring unit configured to acquire received quality information
indicating received quality of a reference signal in a terminal device; and
a control unit configured to perform cell selection for the teiminal device
5 based on the received quality information,
wherein, when a predetermined condition related to use of weight sets for
beamforming by a base station is satisfied, the control unit does not perform the
selection based on the received quality inforination.
(22)
10 A readable recording medium having a program recorded thereon, the
program causing a processor to function as:
an acquiring unit configured to acquire received quality information
indicating received quality of a reference signal in a terminal device; and
a control unit configured to perform cell selection for the terminal device
15 based on the received quality information,
wherein, when a predetermined condition related to use of weight sets for
beamforming by a base station is satisfied, the control unit does not perform the
selection based on the received quality information.
(23)
20 A program for causing a processor to function as:
an acquiring unit configured to acquire one or more weight sets for
beamforming; and
a control unit configured to control wireless communication by a base
station such that the base station transmits a signal using the one or more weight sets,
25 wherein the control unit controls the wireless communication such that the
one or more weight sets are used to transmit a signal in limited radio resources.
(24)
A readable recording medium having a program recorded thereon, the
program causing a processor to function as:
30 an acquiring unit configured to acquire one or more weight sets for
beamfornling; and
a control unit configured to control wireless commu~lication by a base
station such that the base station transmits a signal using the one or more wcight sets,
wherein the control unit controls the wireless commu~lication such that the
one or more weight sets are used to transmit a signal in limited radio resources.

Claim 1
A device comprising:
an acquiring unit configured to acquire received quality information
5 indicating received quality of a reference signal in a terminal device; and
a control unit configured to perform cell selection for the terminal device
based on the received quality information,
wherein, when a predetermined condition related to use of weight sets for
beamforming by a base station is satisfied, the control unit does not perform the
10 selection based on the received quality information.
Claim 2
The device according to claim 1,
wherein the predetermined condition is a condition that a use situation of the
15 weight sets for beamforming by the base station be changed by a predetermined
degree or more.
Claim 3
The device according to claim 2,
20 wherein the predetermined coi~dition is a condition that a weight set for
beamforming used by the base station be changed by a predetermined degree or more.
Claim 4
The device according to claim 2,
25 wherein the predetermined condition is a condition that a use frequency of
the weight sets for beamforming by the base station be changed by a predetermined
degree or more.
Claim 5
The device according to claim 2,
wherein the colltrol unit does not perform the selection based on the
received quality information for a predetermined period after the predetermined
condition is satisfied.
Claim 6
5 The device according to claim 1,
wherein the predetermined condition is a condition that a use frequency of
the weight sets for beamforming by the base station be equal to or greater than a
predetermined frequency.
10 Claim 7
The device according to claim 4,
wherein the use frequency is an amount or a ratio of radio resources through
which the base station transmits a signal using a weight set for beamforming, and
the predetermined frequency is a predetermined amount or ratio.
15
Claim 8
The device according to claim 1,
wherein the reference signal is a reference signal that is transmitted in a
frequency band, and
20 the predetermined condition is a condition related to the use of the weight
sets for beamforming by the base station in the frequency band.
Claim 9
The device according to claim 1,
25 wherein the base station is a base station to which the terminal device is
connected or a neighbor base station of the base station to which the terminal device
is connected.
Claim 10
The device according to claim 1,
wherein the device is a base station to which the terminal device is
connected, a base station device for the base station, or a module for the base station
device,
the received quality information is information that is reported by the
terminal device to the base station to which the terminal device is connected, and
6 a cell is a target cell of a handover of the terminal device or a secondary cell
of carrier aggregation for the terminal device.
Claim 11
The device according to claim 1,
wherein the device is the terminal device or a module for the terminal
device, and
the selection is cell selection or cell reselection by the terminal device.
Claim 12
15 The device according to claim 10,
wherein the control unit controls wireless communicatioil by the base
station to which the terminal device is connected such that the base station to which
the terminal device is connected transmits a signal using one or more weight sets for
beamforming, and
20 the control unit controls the wireless communication such that the one or
more weight sets are used to transmit a signal in limited radio resources.
Claim 13
A method comprising:
25 acquiring received quality information indicating received quality of a
reference signal in a terminal device; and
performing, by a processor, cell selection for the terminal device based on
the received quality information,
wherein, when a predetermined condition related to use of weight sets for
30 beamforming by a base station is satisfied, the selection is not performed based on
the received quality information.
Clairn 14
A device comprising:
an acquiring unit configured to acquire one or more weight sets for
5 beamforming; and
a control unit configured to control wireless communication by a base
station such that the base station transmits a signal using the one or more weight sets,
wherein the control unit controls the wireless communication such that the
one or more weight sets are used to transmit a signal in limited radio resources.
10
Claim 15
The device according to claim 14,
wherein the limited radio resources are radio resources of a predetermined
amount or a predetermined ratio or less.
15
Claim 16
The device according to claim 14,
wherein the limited radio resources are radio resources of some bands
among frequency bands, and
20 the some bands are bands other than a predetermined band among the
frequency bands.
Claim 17
The device according to claim 16,
25 wherein the control unit notifies a terminal device of the predetermined
band.
Claim 18
The device according to claim 14,
30 wherein the control unit multiplies a signal by the one or more weight sets
and thus controls the wireless communication.
Claim 19
The device according to claim 14,
wl~erein the device is the base station, a base station device for the base
5 station, or a module for the base station device.
Claun 20
A method comprising:
acquiring one or more weight sets for beanlforn~inga; nd
10 controlling, by a processor, wireless communication by a base station such
that the base station transmits a signal using the one or more weight sets,
wherein the controlling of the wireless communication includes controlling,
by the processor, the wireless communication such that the one or more weight sets
are used to transmit a signal in limited radio resources