APPARATUS AND METHOD
Technical Field
The present disclosure relates to apparatuses and methods.
Background Art
SP364985WOOO
In the Third Generation Partnership Project (3GPP), various techniques for
improving the capacity of a cellular system are currently studied in order to
accommodate explosively increasing traffic. It is also envisaged that the required
15 capacity will become about 1000 times the current capacity in the future.
Techniques such as multi-user multi-input multiple-input multiple-output (MUMIMO),
coordinated multipoint (CoMP), and the like could increase the capacity of
a cellular system by a factor of as low as less than ten. Therefore, there is a demand
for an innovative technique.
20 [0003]
For example, as a technique for significantly increasing the capacity of a
cellular system, a base station may perform beamfonning using a directional antenna
including a large number of antenna elements (e.g., about 100 antenna elements).
Such a technique is a kind of technique called large-scale MIMO or massive MIMO.
25 By such beamforming, the half-width of a beam is narrowed. In other words, a
sharp beam is formed. Also, if the large number of antenna elements are arranged
in a plane, a beam aimed in a desired three-dimensional direction can be formed.
[0004]
For example, Patent Literatures I to 3 disclose techniques applied when a
30 directional beam aimed in a three-dimensional direction is used.
Patent Literature
[0005]
5 Patent Literature I :
Patent Literature 2:
Patent Literature 3:
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Citation List
JP 2014-204305A
JP 2014-53811A
JP 2014-64294A
Disclosure of Invention
SP364985WOOO
10 Technical Problem
[0006]
Measurement of a CQI in UE is performed mainly on the basis of a result of
measuring a received power of a reference signal. However, there is a case in
which a difference occurs between the received power of the reference signal and the
15 received power of a data signal. lhis difference can similarly occur in a signal
from a serving eNB and a signal from a neighbor eNB. Therefore, there is a case in
which a CQI that indicates an interference condition of the reference signal that is
different from an interference condition of the data signal is fed back to eNB.
20
[0007]
Thus, it is desirable to provide a mechanism capable of more appropriately
ascertaining an interference condition of a data signal.
Solution to Problem
[0008]
25 According to the present disclosure, there is provided an apparatus
including: a processing unit that feeds back a channel quality indicator (CQI) of a
serving base station, which is calculated on a basis of results of measuring reference
signals received from the serving base station and a neighbor base station and
information related to a power difference between the reference signal and a data
30 signal of the neighbor base station, to the serving base station.
[0009]
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In addition, according to the present disclosure, there is provided an
apparatus including: a processing unit that provides a notification of information
related to a power difference between a reference signal and a data signal of a
neighbor base station to a terminal apparatus under the control of the apparatus and
5 receives feedback of a CQI that is calculated on a basis of results of measuring
reference signals that are received from a serving base station and the neighbor base
station and information related to the difference from the terminal apparatus.
[0010]
In addition, according to the present disclosure, there is provided a method
10 including: feeding back a channel quality indicator (CQI) of a serving base station,
which is calculated on a basis of results of measuring reference signals received from
the serving base station and a neighbor base station and information related to a
power differenCe between the reference signal and a data signal of the neighbor base
station, to the serving base station.
15
Advantageous Effects of Invention
[0011]
According to the present disclosure, a mechanism capable of more
appropriately ascertaining an interference condition of a data signal is provided as
20 described above. Note that the effects described above are not necessarily
limitative. 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.
25 Brief Description of Drawings
[0012]
[FIG. I] FIG. I is a diagram for describing a weight set for large-scale MIMO
beam forming.
[FIG. 2] FIG. 2 is a diagram for describing an example of a case m which
30 beamforming oflarge-scale MIMO is performed.
(FIG. 3] FIG. 3 is a diagram for describing a relationship between multiplication of
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weight coefficients and insertion of a reference signal.
[FIG. 4] FIG. 4 is a diagram for describing a relationship between multiplication by a
weight coefficient and insertion of a reference signal in a new approach.
[FIG. 5] FIG. 5 is a flowchart illustrating an example of a flow of CQI calculation
5 processing executed by UE of LTE in the related art.
[FIG. 6] FIG. 6 is a diagram for describing an example of a schematic configuration
of a system according to an embodiment ofthe present disclosure.
[FIG. 7] FIG. 7 is a block diagram illustrating an example of a configuration of a base
station according to the present embodiment
10 [FIG. 8] FIG. 8 is a block diagram illustrating an example of a configuration of a
terminal apparatus according to the present embodiment
[FIG. 9] FIG. 9 is an explanatory diagram for explaining technical :features of a first
embodiment
[FIG. 1 0} FIG. 10 is an explanatory diagram for explaining technical features of the
15 embodiment.
[FIG. II} FIG. II is an explanatory diagram for explaining technical features of the
embodiment.
{FIG. 12] FIG. 12 is an explanatory diagram for explaining technical features of the
embodiment
20 [FIG. 13]1 FIG. 13 is an explanatory diagram for explaining technical features of a
second embodiment.
[FIG. 14] FIG. 14 is an explanatory diagram for explaining technical features of the
embodiment.
[FIG. 15] FIG. 15 is an explanatory diagram for explaining technical features of the
25 embodiment.
[FIG. 16] FIG. 16 is an explanatory diagram for explaining technical features of the
embodiment.
[FIG. 17] FIG. 17 is a block diagram illustrating a first example of a schematic
configuration of an eN B.
30 [FIG. 18] FIG. 18 is a block diagram illustrating a second example of the schematic
configuration of the eNB.
5
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[FIG. I 9] FIG. 19 is a block diagram illustrating an example of a schematic
configuration of a smartphone.
[FIG. 20] FIG. 20 is a block diagram illustrating an example of a schematic
configuration of a car navigation apparatus.
Mode(s) for Carrying Out the Invention
[0013]
Hereinafter, (a) preferred embodiment(s) of the present disclosure will be
described in detail with reference to the appended drawings. Note that, in this
10 specification and the appended drawings, structural elements that have substantially
the same function and structure are denoted with the same reference numerals, and
repeated explanation of these structural elements is omitted.
[0014]
In addition, there are cases in the present specification and the diagrams in
15 which constituent elements having substantially the same functional configuration
are distinguished from each other by affixing different letters to the same reference
numbers. For example, a plurality of constituent elements having substantially the
same functional configuration are distinguished, like neighbor base stations 300A
and 300B, if necessary. However, when there is no particular need to distinguish a
20 plurality of constituent elements having substantially 1 the same functional
configuration from each other, only the same reference number is affixed thereto.
For example, when there is no particular need to distinguish· neighbor base stations
300A and 300B, they are referred to simply as neighbor base stations 300.
25
[0015]
Note that the description will be given in the following order.
I. Introduction
1.1. Related techniques
1.2, Consideration related to embodiment of the present disclosure
2. Configuration example
30 2.1. Schematic configuration example of system
2.2. Configuration example of base station
2.3. Configuration ofterminal apparatus
3. First embodiment
3.1. Technical problems
3 .2. Technical features
5 4. Second embodiment
4.1. Technical problems
4.2. Technical features
5. Application examples
6. Conclusion
10. [0016]
<<1. Introduction>>
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First of all, techniques related to an embodiment of the present disclosure
and consideration related to the present embodiment will be described with reference
to FIGS. I to 5.
15 [0017]

Beamforming and measurement will be described as techniques related to
an embodiment of the present disclosure with reference to FIGS. I to 4.
[0018]
20 . (I) Beamforming
(a) Necessity oflarge-scale MIMO
In the 3GPP, various techniques for improving the capacity of a cellular
system are currently studied in order to accommodate ·explosively increasing traffic.
It is envisaged that the required capacity will become. about 1000 times the current
25 i capacity in the future. Techniques such as MU-MIMO, CoMP, and the like could
increase the capacity of a cellular system by a factor of as low as less than ten.
Therefore, there is a demand for an innovative technique.
[0019]
Release I 0 of the 3GPP specifies that eN ode B is equipped with eight
30 antennas. Therefore, the antennas can provide eight-layer MIMO in the case of
single-user multi-input multiple-input multiple-output (SU-MIMO). Eight-layer
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MIMO is a technique of spatially multiplexing eight separate streams. Alternatively,
the antennas can provide four-user two-layer MU-MIMO.
(0020]
User equipment (UE) has only a small space for accommodating an antenna,
5 and limited processing capability, and therefore, it is difficult to increase the number
of antenna elements in the antenna of UE. However, recent advances in antenna
mounting technology have allowed eN node B to accommodate a directional antenna
including about I 00 antenna elements.
10
[0021]
For example, as a technique for significantly increasing the capacity of a
cellular system, a base station may perform beamfonning using a directional antenna
including a large number of antenna elements (e.g., about I 00 antenna elements).
Such a technique is a kind of technique called large-scale MIMO or massive MIMO.
By such beamforming, the half-width of a beam is narrowed. In other words, a
15 sharp beam is formed. Also, if the large number of antenna elements are arranged
in a plane, a beam aimed in a desired three-dimensional direction can be formed.
For example, it has been proposed that, by forming a beam aimed at a higher position
than that of a base station {e.g., a higher floor of a high-rise building), a signal is
transmitted to a terminal apparatus located at that position.
20 [0022]
In typical beamfmming, the direction: of a beam can be changed in the
horizontal direction. Therefore, it can be said that the typical beamfmming is twodimensional
beamforming. Meanwhile, in large-scale MIMO (or massive MIMO)
beam forming, the direction of a beam can be changed in the vertical direction as well
25 as the horizontal direction. Therefore, it can be said that large-scale MIMO
beam forming is three-dimensional beamforming;
[0023]
Note that the increase in the number of antennas allows for an increase in
the number ofMU-MIMO users. Such a technique is another form of the technique
30 called large-scale MIMO or massive MIMO. Note that when the number of
antennas in UE is two, the number of spatially separated streams is two for a single
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piece of UE, and therefore, it is more reasonable to increase the number of MUMJMO
users than to increase the number of streams for a single piece of UE.
[0024]
(b) Weight set
5 A set of weight for beamfonning are represented by a complex number (i.e.,
a set of weight coefficients for a plurality of antenna elements). An example of a
weight set particularly for large-scale MIMO beamforming will now be described
with reference to FIG I.
[0025]
10 FIG. 1 IS a diagram for describing a weight set for large-scale MIMO
beamfonning. FIG. I shows antenna elements arranged in a grid pattern. In
addition, FIG. 1 also shows two orthogonal axes x and y in a plane in which the
antenna elements arc arranged, and an axis z perpendicular to the plane. Here, the
direction of a beam to be formed is, for example, represented by an angle phi (Greek
15 letter) and an angle theta (Greek letter). The angle phi (Greek letter) is an angle
between an xy-planc component of the direction of a beam and the x-axis. Also, the
angle theta (Greek letter) is an angle between the beam direction and the z-axis. In
this case, for example, the weight coefficient V m. n of an antenna element which is mth
in the x-axis direction and n-th in they-axis direction is represented as follows.
20 [0026]
[Math. 1]
Vm.JB;tp,f)= exp(j27r ~ {(m -l)dx sin(B)cos(tp)+ (n -l)dy sin(B)sin(tp)})
[0027]
In formula (I), f is a frequency, and c is the speed of light. Also, j is the
25 imaginary unit of a complex number. Also, dx is an interval between each antenna
element in the x-axis direction, and dy is an interval between each antenna element in
the y-axis direction. Note that the coordinates of an antenna element are
represented as follows.
[0028]
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[Math. 2]
X= (m -l)dx, y=(n-l)dy
[0029]
A weight set for typical beam forming (two-dimensional beam forming) may
5 be divided into a weight set for acquiring directivity in the horizontal direction and a
weight set for phase adjustment of dual layer MIMO (i.e., a weight set for phase
adjustment between two antenna subarrays corresponding to different polarized
waves). On the other hand, a weight set for beamfonning of large-scale MIMO
(three-dimensional beamforming) may be divided into a first weight set for acquiring
10 directivity in the horizontal direction, a second weight set for acquiring directivity in
the vertical direction, and a third. weight set for phase adjustment of dual layer
MIMO.
[0030]
(c) Change in environment due to large-scale MIMO beam forming
15 When large-scale MIMO beam forming is performed, the gain reaches 10 dB
or more. In a cellular system employing the above beamforming, a significant
change in radio wave environment may occur compared to a conventional cellular
system.
[0031]
20 (d) Case where large-scale MIMO beamforming is perfonned
For example, a base station in urban areas may fonn a beam aimed at a
high-rise building. Also, even in rural areas, a base station of a small cell may form
a beam aimed at an area around the base station. Note that it is highly likely that a
base station of a macro-cell in rural areas does not perform large-scale MIMO
25 beamforming.
[0032]
FIG. 2 is a diagram for describing an example of a case in which
beamforming of large-scale MIMO is performed. Referring to FIG. 2, a base station
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71 and a high-rise building 73 are illustrated. For example, the base station 71
forms a directional beam 79 toward the high-rise building 73 in addition to
directional beams 75 and 77 toward the ground.
[0033]
5 (2) Measurement
Measurement includes measurement for selecting a cell and measurement
for feeding back a channel quality indicator (CQI) and the like after connection.
The latter is required to be performed in a shorter time. Measurement of an amount
of interference from a neighbor cell as well as measurement of quality of a serving
10 cell may be considered as a kind of such CQI measurement.
[0034]
(a) CQI measurement
Although a cell-specific reference signal (CRS) may be used for CQI
measurement, a channel state information reference signal (CSI-RS) has mainly been
15 used for CQI measurement since release 10.
(0035]
A CSI-RS is transmitted without beamforming, similar to a CRS. That is,
the CSI-RS is transmitted without beingmultiplied by a weight set for beamforming,
similar to a CRS. A specific example of this will be described with reference to FIG.
20 3.
(0036]
FIG. 3 is a diagram for describing the relationship between multiplication of
weight coefficients and insertion (or mapping) of a reference signal. Referring to
FIG. 3, a transmission signal 82 corresponding to each antenna element 81 is
25 complex-multiplied by a weight coefficient 83 by a multiplier 84. Thereafter, the
transmission signal 82 complex-multiplied by the weight coefficient 83 is transmitted
from the antenna element 81. Also, a demodulation reference signal (DM-RS) 85 is
inserted before the multiplier 84, and is complex-multiplied by the weight coefficient
83 by the multiplier 84. Thereafter, the DM-RS 85 complex-multiplied by the
30 weight coefficient 83 is transmitted from the antenna element 81. Meanwhile, a .
CRS 86 (and a CSI-RS) is inserted after the multiplier 84. Thereafter, the CRS 86
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(and the CSI-RS) is transmitted from the antenna element 81 without being
multiplied by the weight coefficient 83.
[0037]
Since a CSI-RS is transmitted without beamforming as described above, a
5 pure channel (or a channel response H) which is not affected by heamfonning is
estimated when measurement of the CSI-RS is performed. This channel H is used
and a rank indicator (RI), a precoding matrix indicator (PM!) and a channel quality
indicator (CQI) are fed back. Note that only a CQI is fed back depending on a
transmission mode. Also, an amount ofinterference may be fed back.
10 [0038]
(b) CSI-RS
Since a CSI-RS is transmitted without beamfonning before release 12 as
described above, · the . pure channel H which is not affected by beam forming is
estimated when measurement of the CSI-RS is performed. Accordingly, the CSI-
15 RS has been operated like a CRS.
[0039]
A CRS is used for cell selection, synchronization and the like and thus a
CRS transmission frequency is higher than a CSI-RS transmission frequency. That
is, a CSI-RS period is longer than a CRS period.
20 (0040]
There may be a first approach for transmitting a CSI-RS without
beamforming and a second approach for transmitting a CSI-RS with beamforming
(i.e., transmitting a CSI-RS over a directional beam) in a large-scale MIMO
environment. It can be said that the first approach is a conventional approach· and
25 the second approach is a new approach. A relationship betw.een multiplication by a
weight coefficient and insertion of a reference signal in the new approach (second
approach) will be described below with reference to FIG. 4.
[0041]
FIG. 4 is a diagram for describing relationship between multiplication by a
30 weight coefficient and insertion (or mapping) of a reference signal in the new
approach. Referring to FIG. 4, a transmission signal 92 corresponding to each
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antenna element 91 is complex-multiplied by a weight coefficient 93 by a multiplier
94. Thereafter, 'the transmission signal 92 complex-multiplied by the weight
coefficient 93 is transmitted from the antenna element 91. Also, a DM-RS 95 is
inserted before the multiplier 94, and is complex-multiplied by the weight coefficient
5 93 by the multiplier 94. Thereafter, the DM-RS 95 complex-multiplied by the
weight coefficient 93 is transmitted from the antenna element 91. Further, a CSIRS
96 is insetted. in fi·ont of the multiplier 94, and is complex-multiplied by the
weight coefficient 93 in the multiplier 94. Then, the CSI-RS 96 complex-multiplied
by the weight coefficient 93 is transmitted from the antenna element 91.
10 Meanwhile, a CRS 97 (and a normal CSI-RS) is inserted after the multiplier 94.
Thereafter, the CRS 97 (and the normal CSI-RS) is transmitted from the antenna
element 91 without being multiplied by the weight coefficient 93.
[0042]
<1.2. Consideration related to embodiment of present disclosure>
15 Consideration related to an embodiment of the present disclosure will be
described with reference to FIG. 5.
[0043]
(I) CSI-RS
A CSI-RS is defined in release I 0. A normal CSI-RS is also referred to as
20 a non-zero-power CSI-RS. The purpose of the CSI-RS is to acquire a pure channel
and thus the CSI-RS is transmitted without beamforming.
[0044]
Also, a zero-power CSI-RS is defined. The zero-power CSI-RS is defined
in order to enable easy observation of relatively weak signals from other eNBs.
25 Since an eNB does not transmit a signal in radio resources (resource elements) for
the zero-power CSI-RS, a UE can receive signals from other eNBs in .the radio
30
resources. The zero-power CSI-RS is also referred to as an interference
measurement resource (IMR).
[0045]
A CSI-RS period is variable between 5 ms and 80 ms. In addition, 400
radio resources are prepared in one subframe as candidates for radio resources in
which the CSI-RS is transmitted.
[0046)
13/62
SP364985WOOO
Conventionally, only one CSI-RS is configured for one ceiL On the other
hand, a plurality of zero-power CSJ-RSs can be configured • for one cell.
5 Accordingly, when a serving eNB of a UE configures a zero-power CSI-RS in
accordance with a configuration of a CSJ-RS of a neighbor eNB, the UE can perform
measurement of the CSI-RS of the neighbor eNB without being affected by a signal
from the serving eNB.
10
[0047]
Note that a CSI-RS configuration is cell-specific. A UE may be notified of
the configuration through signaling of a higher layer.
[0048]
The embodiment is based on the assumption that the approach of
transmitting the CSI-RS with beamforming, which has been described above with
15 reference to riG. 4, is employed. However, an approach of transmitting the CSI-RS
with no beamforming may also be employed according to the embodiment That is,
a case in which only the CSI-RS with beamforming is transmitted and a case in
which the CSI-RS with beamforming and the CSI-RS with no beamforming ru·e
present together are assumed according to the embodiment
20 (0049]
(2) Necessity of optimization of beam forming
When only a desired directional beam arrives at a UE, the UE can obtain
high received quality. On the other hand, when not only a desired directional beam
but also other directional beams arrive at a UE, received quality 'of the UE may
25 deteriorate; For example, an interference can occur between refleded beams, and
reception quality can deteriorate in an environment with a large number of reflected
waves. In. addition, an interference with beams from the neighbor; eNB can occur,
for example, and reception quality can deteriorate.
[0050]
30 In ·order to suppress such interference, first of all, it is impottant for an eNB
to ascertain a situation of interference of a directional beam. A UE reporting a
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situation of interference of a directional beam to the eNB is c'onsidered because the
eNB. cannot be aware of the situation of such interference of the directional beam.
For example, calculating an amount of interference of a directional beam other than a
desired directional beam from a CSI-RS is considered. Also, use of a CS! feedback
5 procedure is considered.
(0051]
In general, there are two types of channel quality measurement. One type
ts radio resource management (RRM) measurement such as measurement of
reference signal received power (RSRP) and reference signal received quality
10 (RSRQ) and the other is measurement for deciding an RI, a CQI, a PMI and the like
included in CSI. The former is mainly performed for cell selection by both a UE in
an RRC idle mode and a UE in an RRC connected mode. On the other hand, the
latten is performed to recognize an interference situation by a UE in an RRC
connected mode.
15 (0052]
(3) CQl
Settings related to the reference signal that the UE uses for calculating the
CQl is called a CSI-RS configuration. The CSI-RS configuration includes
information that indicates the position and the cycle of the CSI-RS (the position of
20 the CSI-RS in a resource block and a cycle of a sub-frame into which the CSI-RS is
inserted) that are provided by the serving eNB. The UE can .ascertain the position
and the cycle of the CSI-RS with reference to the CSI-RS .configuration and can
pertorm measurement and reporting using the CSI-RS. In this manner, the UE can
receive a desired signal that has been transmitted from the serving eNB by using
25 transmission settings suitable for itself.
[0053]
For calculating the CQI, information about the .received power of an
interference signal is also used as well as the received power, of the desired signal.
Here, the interference signal is a signal that comes from the neighbor eNB. In order
30 for the UE to be able to measure the interference signal,· a notification of the
information that indicates the position and the cycle of the IMR for measuring the
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, interference signal from the neighbor eNB is provided as an IMR configuration to the
UE. The U E can ascertain the position and the cycle of the IMR with reference to
• the IMR configuration and can measure the interference signal. Then, the UE
calculates the CQI by using the results of measuring the desired signal and the
5 interference signal. The IMR typically receives the CSI-RS that comes from the
neighbor eNR
. [0054]
However, one IMR can measure one or more reference signals from one or
more neighbor eNBs. That is, it is difficult to identity from which beam from
10 ! which neighbor eNB the interference comes and how large the interference is, from
the measurement result of the IMR. Therefore, the measurement result of the IMR
is used for measuring the total amount of the interference .
• [0055]
( 4) First estimation error of interference power
15 ' In order for the UE to accurately calculate the CQI, it is important to
accurately estimate the power of the desired signal (optical signal power) and the
power of the interference signal (interference signal power) on the basis of downlink
channel infom1ation that has been obtained by measuring the CSI-RS. In a case in
which these values have errors, the CQI becomes not accurate, a modulation scheme
20 is incorrectly selected on the side of the eNB, and a .decrease in a throughput can
. • : occur, for example.
[0056]
The point to be noted here is that the CSI-RS isi a reference signal and is not
· a data signal. That is, a difference in received power can occur between the
25 reference signal and the data signal. Therefore, it is desirable that the UE estimate
the received power of the desired data signal (that is, the data signal from the serving
'. eNB) and the received power of the interference data signal (that is, the data signal
, from the neighbor eNB) and calculate the CQT on the basis of the estimation result.
Thus, the UE can estimate the received power of the desired data signal on the basis
30 • of the result of measuring the CSI-RS from the serving eNR In addition, the UE
· can estimate the received power of the interference data signal by measuring the
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signal (typically, the CSI-RS) form the neighbor eNB with the !MR.
[0057]
SP364985WOOO
However, the result of estimating the received power of the desired data
signal and the interference data signal can include errors.
5 [0058]
One of causes of the error included in the estimated received power of the
desired data signal is that there is a difference between the received power of the
CSI-RS from the serving eNB and the received power of the physical downlink
shared channel (POSCH). According to the 3GPP standard (3GPP TS 36.213), a
' 10 parameter Pc is provided in the CSI-RS configuration in order for the UE to be able
to estimate the received power of the desired data signal in consideration of the
difference. The parameter Pc is an estimated ratio of energy per resource element
(EPRE) of the POSCH with respect to EPRE of the CSI-RS. The UE can ascertain
the power difference between the CSI-RS from the serving eNB and the POSCH by
' 15 acquiring the parameter Pc from the CSI-RS configuration and can more accurately
correct the received power of the desired data signal. Hereinafter, an example of a
flow of CQI calculation processing in the LTE in the related art will be described
with reference to FIG. 5.
20
[0059]
FIG. 5 is a flowchart illustrating an example of a flow of CQI calculation
processing executed by the UE of the LTE in the related art. As illustrated in FIG. 5,
the UE estimates the received power of the desired data signal on the basis of the
CSI-RS of the serving eNB (Step S 102). Then, the UE corrects the error in the
estimated received power by using Pc of the serving eNB (Step S I 04). Meanwhile,
25 the UE estimates the received power of the interference data signal on the basis of
the CSI-RS of the neighbor eNB (Step S112). Then, the UE calculates the CQI on
the basis of these estimation results (Step S120).
[0060]
Here, the difference between the received power of the CSI-RS from the
30 neighbor eNB and the received power of the POSCH is exemplified as one of the
causes of the error in the estimated received power of the interference data signal in a
5
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similar manner to the desired data signal. However, it is difficult for the UE to
reduce the error in the estimated received power of the interference data signal since
a notification of the parameter Pc of the neighbor eNB is not provided.
[0061]
Thus, a technique of providing Pc of the neighbor eNB to the UE will be
provided in the first embodiment.
[0062]
( 5) Second error in estimated interference power
The method of estimating the received power of the interference data signal
10 on the basis of the CSI-RS from the neighbor eNB has been described above on the
assumption that the data signal is transmitted from the neighbor eNB. However,
there is also a case in which no data signal is transmitted, and a large error in the
estimation occurs since the interference power estimated on the basis of the CSI-RS
does not actually come in such a case. In the large-scale MIMO system in which an
15 antenna gain is larger than that of the LTE·in the related art, whether or not the data
signal is transmitted (that is, whether the POSCH is used or not used) greatly affects
the error in the estimated interference power.
{0063]
Thus, a technique capable of reducing the error in the estimation that is
20 caused depending on whether the POSCH is used or not used by exchanging
information related to transmission schedules of the POSCH between eNBs will be
provided in the second embodiment.
(0064]
<<2. Configuration example>>
25 <2.1. Schematic configuration example of system>
Next, a schematic configuration of a communication system I according to
an embodiment of the present disclosure will be described with reference to FIG 6.
FIG. 6 is a diagram for describing an example of the schematic configuration of the
communication system I according to an embodiment of the present disclosure.
30 Referring to FIG 6, the system I includes a base station I 00, a terminal apparatus
200, and a neighbor base station 300. The system I is a system which complies
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with, for example, LTE, LTE-Advanced, or similar communication standards.
[0065]
(Base station I 00)
The base station I 00 perfonns wireless communication with the terminal
5 apparatuses 200. For example, the base station I 00 performs wireless
communication with the terminal apparatuses 200 located in a cell I 0 of the base
station I 00.
[0066]
Particularly, in the embodiment, the base station I 00 performs beam forming.
10 For example, the beamforming is beamforming of large-scale MIMO_ The
beamforming may also be referred to as beamforming of massive MIMO,
beamforming of free dimension . MIMO or three-dimensional beamforming.
Specifically, for example, the base station I 00 includes a directional antenna usable
for large-scale MIMO and performs beamforming of large-scale MIMO by
15 multiplying a transmission signal by a weight set for the directional antenna.
[0067]
Further, the base station I 00 can transmit the reference signal for channel
quality measurement by a directional beam, in particular, in the embodiment It is a
matter of course that the base station 100 may transmit the reference signal without
20 using the directional beam. For example, the reference signal is the CSI-RS. In
addition, the base station I 00 can transmit the data signal by a directional beam. It
is a matter of course that the base station I 00 may transmit the data signal without
using the directional beam. For example, the data signal is the PDSCH.
[0068]
25 (Terminal apparatus 200)
The terminal apparatus 200 performs wireless communication with a base
station. For example, the terminal apparatus 200 performs wireless communication
with the base station I 00 when located within a cell I 0 of the base station 100. For
example, the terminal apparatus 200 performs wireless communication with a
30 neighbor base station 300 when located within a cell 30 of the neighbor base station
300.
SP364985WOOO
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[0069]
(Neighbor base station 300)
The neighbor base station 300 is a neighbor base station of the base station
I 00. For example, the neighbor base station 300 has a similar configuration to that
5 of the base station I 00 and perfonns similar operations to those of the base station
I 00. Although FIG. 6 illustrates two neighbor base stations 300, it is a matter of
course that a single base station 300 may be included in the system I, or three or
more base stations 300 may be included in the system I.
10
[0070]
In the embodiment, the terminal apparatus 200 is assumed to be connected
to the base station 100. That is, the base station l 00 is a serving base station of the
terminal apparatus 200, and the cell I 0 is a serving cell of the terminal apparatus 200.
The solid line arrow in the drawing represents the desired signal transmitted to the
terminal apparatus 200, and the broken line arrow represents the interference signal.
15 [0071]
Note that both the base station I 00 and the neighbor base station 300 may
be base stations of macro cells. Altematively, both the base station I 00 and the
neighbor base station 300 may be base stations of small cells. Altematively, one of
the base station I 00 and the neighbor base station 300 may be a base station of a
20 macro cell and the other of the base station I 00 and the neighbor base station 300
may be a base station of a small cell.
[0072]
<2.2. Configuration example of base station>
Next, an example of the configuration of the base station I 00 according to
25 an embodiment of the present-disclosure will be described with reference to FIG. 7.
FIG. 7 is a block diagram showing an example of the configuration of the base
station 100 according to the embodiment of the present disclosure. Referring to FIG.
7, the base station I 00 includes an antenna unit II 0, a wireless communication unit
120, a network communication unit 130, a storage unit 140, and a processing unit
30 150.
[0073]
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(Antenna unit II 0)
The antenna unit 110 radiates a signal output by the wireless communication
unit 120, in the form of.radio waves, into space. In addition, the antenna unit 110
also converts radio waves in space into a signal, and outputs the signal to the wireless
5 communication unit 120.
[0074]
For example, the antenna unit 110 includes a directional antenna. For
example, the directional antenna is a directional antenna which can be used in largescaleMlMO.
10 [0075]
(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 apparatus 200 and receives an uplink signal from the terminal apparatus 200.
15 [0076]
(Network communication unit 130)
The network communication unit 130 transmits and receives information.
For exantple, the network communication unit 130 transmits information to other
nodes and receives information from other nodes. For example, the other nodes
20 include other base stations (for example, neighbor base station 300) and a core
network node.
[0077]
(Storage unit 140)
The storage unit 140 stores programs and data for operation of the base
25 station I 00.
[0078]
(Processing unit 150)
The processing unit 150 provides various functions of the base station 100.
The :processing unit 150 includes a setting unit 151 and a communication control unit
30 153.· Note that the processing unit 150 may further include other components in
addition to such components. That is, the processing unit 150 may perform
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operations other than operations of such components.
[0079]
SP364985WOOO
Specific operations of the setting unit 151 and the communication control
unit 153 will be described below in detail.
5 [0080]
<2.3. Configuration of terminal apparatus>
Next, an example of the configuration of the terminal apparatus 200
according to an embodiment of the present disclosure will be described with
reference to FIG. 8. FIG. 8 is a block diagram for showing an example of the
10 configuration of the terminal apparatus 200 according to the embodiment of the
present disclosure. Referring to FIG. 8, the terminal apparatus 200 includes an
antenna unit 210,' a wireless communication unit 220, a storage unit 230 and a
processing unit 240.
[0081]
15 (Antenna unit 210)
The antenna unit 210 radiates a signal output by the wireless communication
unit 220, in the form of radio waves, into space. In addition, the antenna unit 210
also converts radio waves in space into a signal, and outputs the signal to the wireless
communication unit 220.
20 [0082]
(Wireless communication unit 220)
The wireless communication unit 220 transmits and receives signals. For
example, the wireless communication unit 220 receives a downlink signal fi·om the
base station I 00 and transmits an uplink signal to the base station 100.
25 [0083]
(Storage unit 230)·
The storage unit 230 stores a program and data for operation of the terminal
apparatus 200.
[0084]
30 (Processing unit 240)
The processing unit 240 provides a variety of functions of the terminal
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apparatus 200. The processing unit 240 includes an acquisition unit 241 and a
measurement unit 243. Note that the processing unit 240 can further include
components other than these components. That is, the processing unit 240 can
perform operations other than the operations of these components.
5 [0085]
10
Specific operations of the acquisition unit 241 and the measurement unit
243 will be described later in detail.
[0086]
<<3. First embodiment>>
to 12.
[0087]
Hereinafter, a first embodiment will be described with reference to FIGS. 9
<3. L Technical problems>
(I) First problem
15 A technical problem of the embodiment is the error in· the estimated
received poiwer of the interference data signal that is caused by the difference in the
received power of the reference signal and the data signal as described above.
Therefore, a technology of providing a notification of a Pc of the neighbor base
station 300 to the terminal apparatus 200 will be provided first in the embodiment.
20 [0088]
(2) Second problem
However, there is also a case in which it is difficult to reduce· the error in the
estimated received power of the interference data signal even if it becomes possible
for the terminal apparatus 200 to acquire the parameter Pc of the: neighbor base
25 station 300. This is because the parameter Pc can be received in a state in which
CSI-RSs are present together in a single IMR since the parameter Pc can be applied
to the received power of the CSI-RSs corresponding to the parameter Pc.
[0089]
In the LTE in the related mi, such an error in the estimated received power
30 of the interference data signal that is caused by such a problem is· not patticularly
considered.as a problem. This is because the number of antenna elements mounted
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on the eNB is small and the environment of the interference power does not greatly
vary.
[0090]
Meanwhile, since the environment of the interference power can greatly
5 vary in the large-scale MIMO, the error in the estimated received power of the
interference data signal can become a severe problem.
[0091]
Specifically, a CSI-RS with beamfonning and a CSI-RS with no
beamfonning are considered first in the large-scale M!MO.' There are cases in
10 which the POSCH is subjected to the beam forming for each eNB in both schemes.
In addition, the number of beams that are multiplexed at the same time changes in
some cases, and in such cases, the power of each beam changes. In addition, a case
in which an excessively large antenna gain is not used in order to avoid interference
with the neighbor cell is also assumed. As described above, the degree of freedom
15 of the antenna gain obtained by the beamforming can become larger in the
environment of the large-scale MIMO as compared with the previous one.
[0092]
Therefore, it is possible to state that there is a high likelihood that the degree
of freedom in setting the parameter Pc for each CSl-RS configuration will be
20 significantly greater than that in the previous one (specifically, l dB steps from -8 dB
to 15 dB). In a case in which the degree of freedom in setting a Pc is significantly
large, it is difficult to reduce the error in the estimation by using a plurality of Pes
that are set with a high degree of fi·eedom in the settings' related to results of
measuring a plurality of CSI-RSs from a single neighbor eNB with a single !MR.
25 Similar difficulty also occurs in a case in which a plurality of CSI-RSs from a
plurality of neighbor eNBs are present together in a single IMR,
[0093]
A method of restricting the degree of freedom in setting a Pc may be
considered as an example of methods for solving this problem. In a case in which
30 the degree of freedom in setting a Pc is restricted, it is considered to be possible to
reduce the error in the estimated received power of the interference data signal on the
SP364985WOOO
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• basis of the result of measuring the !MR. However, if the degree of freedom in
setting a Pc is restricted, there is a possibility that interference due to unnecessary
radiation may occur or the number of UEs that can perform MU-MIMO by using
spatial multiplexing will be restricted.
5 [0094]
Setting an IMR for each CSI-RS may be exemplified as another example of
.the methods for solving the problem. However, overheads of the IMR that occupies
. the wireless resource becomes excessively large in the method. In an environment
in which small base stations are densely arranged, for example, it is assumed that a
10 large number of neighbor base stations as interference sources are present in the
neighborhood of the serving base station. In addition, the number of types
, (directions, for example) of the beams that can be provided by a single base station is
·significantly large in the case ofthe large-scale MIMO. · Therefore, the number of
; !MRs that are set for measuring the CSI-RSs with beamforming from the neighbor
15 · base stations can become huge in a case in which the ,CSl-RSs are provided with
. beam forming.
[0095]
Thus, a technique of more finely measuring the interference from the
neighbor eNB by using a plurality of !MRs in accordance with the setting of a Pc
20 ·will be further provided in the embodiment.
. [0096] '.
<3 .2. Technical features>
• (I) Estimation based on Pc of neighbor base station
The base station 100 (for example, the setting unit 151) provides a
25 notification of infonnation related to a power difference between the CSI-RS of the
·. neighbor base station 300 and the PDSC (that is, the. information related to the
parameter Pc) to the terminal apparatus 200. In this manner, the terminal apparatus
200 (for example, the acquisition unit 241) acquires the information related to the
power difference between the CSI-RS of the neighbor base station 300 and the
30 • · PDSCH (that is, Pc). This station is included in the lMR configuration, for example,
and the notification thereof is provided from the base station 100 to the terminal
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apparatus 200. That is, the IMR configuration includes the information related to a
Pc in addition to the information that indicates the position and the cycle of the !MR.
[0097]
The terminal apparatus 200 (for example, the measurement unit 243)
5 measures the CSI-RSs received from the base station I 00 and the neighbor base
stations 300. Then, the terminal apparatus 200 (for example, the measurement unit
243) calculates the CQI of the neighbor base station 300 on the basis of the results of
measuring the CSI-RSs and the IMR configuration and feeds back the CQI to the
base station 100. Here, the terminal apparatus 200 (measurement unit 243)
, 10 estimates the received power of the interference data signal on the basis of the IMR
configuration and then calculates the CQI. Since the CQI based on the received
power of the interference data signal with a reduced error in the estimation is fed
back, the base station 100 (for example, the communication control unit 153) can
select an appropriate modulation scheme, for example.
15 [0098]
(2) Grouping of interference signals
In the embodiment, reference signals (the CSI-RSs of neighbor base stations
300) are grouped in accordance with Pc. Then, the reference signals are received
by an IMR corresponding to a group (that is, corresponding to Pc of the reference
. 20 signals). Referring to FIG. 9, specific description will be given of this point.
[0099]
As illustrated in FIG. 9, a plurality of !MRs 42 are set for a wireless resource
(typically, a resource block) 40. Pc is set for each IMR 42, and a CSI -RS with the
set Pc arrives the IMR 42. For example, a CSI-RS with Pc of -10 dB is received by
25 the IMR 42A. A CSI-RS with Pc of 0 dB is received by the IMR 42B. A CSl-RS
with Pc of !0 dB is received by the IMR 42C. A CSI-RS with Pc of 20 dB is
received by the IMR 420.
[0 I 00]
The terminal apparatus 200 (for example, the measurement unit 243)
30 estimates the received power of the interference data signal on the basis of the
received power that is measured by each IMR 42. It is a matter of course that one
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or more CSI-RSs can be present and received together by each IMR 42. In that case,
it is difficult to estimate the received power of the interference data signals
corresponding to the individual CSI-RSs. Therefore, the received power that is
estimated by the terminal apparatus 200 is an approximate value of the received
5 power with large interference among the interference data signals.
[0101]
The IMR configuration, the notification of which is provided from the base
station 100 to the terminal apparatus 200, includes the information that indicates Pc
corresponding to each !MR. In this manner, the terminal apparatus 200 can
10 ascertain the CSI-RS with which Pc is to ;arrive which JMR and can estimate the
approximate values of the received power of the interference data signals.
[0102]
The base station 100 (for example, the setting unit 151) sets the position of
the IMR and also sets Pc corresponding to: the JMR. Note that the setting can be
15 performed on the basis of an instruction from an operator who uses an operation and
maintenance (0 & M) interface.
[0103]
It is desirable that the information related to the position of the JMR and
corresponding Pc be shared between the base station I 00 and the neighbor base
20 station 300 in order to cause the CSJ-RS with corresponding Pc to arrive the IMR.
Hereinafter, an example of a sharing method will be described. Note that the
information related to the JMR, which is exchanged between the base station I 00 and
the neighbor base station 300, is also refened to as IMR assignment information
below.
25 [0104]
- First example
A first example is a mode in which the position of the IMR and Pc
corresponding to the IMR of each base station are decided by the operator, and
notifications thereof is provided to each base station. According to the example, the
30 neighbor base stations 300 can transmit the CSJ-RS so as to be received by the lMR
with corresponding Pc from among the IMRs of the base station I 00 since the
SP364985WOOO
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position of the IMR of the base station I 00 and Pc are asce1tained by the neighbor
base station 300. In this manner, the CSI-RSs of the neighbor base stations 300 can
be received by the !MRs corresponding to Pc of the CSI-RSs.
[01 05]
5 In this example, it is not necessary to exchange the infonnation between the
base station I 00 and the neighbor base station 300.
[0106]
- Second example
A second example is a mode in which a rule related to the position of the
10 IMR of each base station and Pc (hereinafter, referred to as a grouping rule) is
decided by the operator, and each base station decides the position of the IMR and Pc
corresponding to the !MR. For example, the grouping rule can include information
that indicates a rough position of !MRs, reference levels of the Pc to be set, the upper
limit number of !MRs, and the like.
15 [0107]
In this example, the base station 100 provides a notification of the lMR
assignment information to the neighbor base stations 300. The lMR assignment
infonnation includes information that indicates the positions of the !MR. ln
addition, the IMR assignment information includes information that indicates Pc
20 corresponding to each IMR in the base station I 00. The neighbor base station 300
transmits the CSI-RS so as to be received by the lMR with corresponding Pc among
the !MRs of the base station I 00 on the basis of the IMR assignment information.
In this manner, the CSI-RSs of the neighbor base stations 300 can be received by the
!MRs corresponding to the Pc of the CSI-RSs. Note that the notification of the
25 information that is common to the base station I 00 and the neighbor base station 300
in the IMR assignment information may be omitted. In a case in which the
positions, and the numbers of the !MRs, setting of corresponding Pc, and the like are
common to the base station I 00 and the neighbor base stations 300, for example, the
notification itself of the IMR assignment information may be omitted.
30 [0108]
-Third example
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A third example is similar to the second example in that the grouping rule is
decided by the operator. As a different point, this example is a mode in which the
base station 100 decides the position of the IMR and Pc corresponding to the IMR on
the basis of the information about the CSI-RS that is transmitted from the neighbor
5 base station 300.
[0 I 09]
In this example, the neighbor base station 300 provides the notification of
the IMR assignment information to the base station 100. The IMR assignment
information includes information that indicates a schedule (a frequency, a time, a
10 beam, and the like) in which the CSI-RS is transmitted. In addition, the IMR
assignment information includes the information that indicates the Pc corresponding
to the CSI-RS. The base station 100 (for example, the setting unit 15 I) sets the
IMR and sets the Pc on the basis of the acquired IMR assignment information. In
this manner, the CSI-RS of the neighbor base station 300 can be received by the IMR
15 corresponding to the Pc of the CSI-RS. Note that the notification of the information
that is common to the base station I 00 and the neighbor base station 300 in the IMR
assignment information may be omitted.
20
[0110]
- Flow of processing
Hereinafter, examples of flows of processing calculating the CQI by the
tenninal apparatus 200 according to the embodiment and processing of the entire
system I will be described with reference to FIGS. I 0 and 11.
[0 II I]
FIG. I 0 is a flowchart illustrating an example of a flow of processing
25 calculating the CQI that is executed by the terminal apparatus 200 according to the
embodiment. As illustrated in FIG. 10, the terminal apparatus 200 (for example, the
measurement unit 243) estimates received power of a desired data signal on the basis
of the CSI-RS of the base station 100 (Step S 1 02). Then, the terminal apparatus
200 (for example, the measurement unit 243) corrects an error in estimated received
30 power by using Pc of the base station 100 (Step S 1 04). Meanwhile, the terminal
apparatus 200 (for example, the measurement unit 243) estimates received power of
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the interference data signal on the basis of the CSI-RS of the neighbor base station
300 (Step S 112). Next, the terminal apparatus 200 (for example, the measurement
unit 243) corrects the received power by using the Pc of the neighbor base station
300 (Step S 114). Then, the tenninal apparatus 200 (for example, the measurement
5 unit 243) calculates the CQI on the basis of these estimation results (Step Sl20).
[0112]
FIG. 11 is a sequence diagram illustrating an example of a flow of
measurement report processing that is executed in the system 1 according to the
embodiment. This sequence is a sequence related to the aforementioned second
10 example. As illustrated. in FIG 11, the base station 100 and the neighbor base
station 300 acquires the ·grouping rule from the operator first (Step S202). The
grouping rule includes, for example, a reference of a level of the Pc to be set, the
upper limit number of the !MRs, and the like. The base station 100 transmits a CSic
RS configuration to the terminal apparatus 200 (Step S204 ). In addition, the base
15 station 100 transmits the IMR configuration to the terminal apparatus 200 (Step
S206). Note that the IMR configuration may be transmitted at the same time as the
CS!-RS configuration (while being included in the CSI-RS configuration, for
example). Next, the base station 100 provides the notification of the IMR
assignment information to the neighbor base station 300 (Step S208). Next, the
20 base station 100 transmits the CSI-RS to the terminal apparatus 200 (Step S210). In
addition, the neighbor base station 300 transmits the CSI-RS to the terminal
apparatus 200 so as to arrive the IMR with the corresponding Pc set by the terminal
apparatus 200, with reference to the IMR assignment information (Step S212).
Then, the terminal apparatus 200 calculates the CQI as described above with
25 reference to FIG. 10 (Step S214) and feeds back the CQI to the base station 100 (Step
S216).
[0 113]
(3) Variations
Variations of the technique related to the groupmg are considered in a
30 variety of ways. Hereinafter, an example thereof will be described.
[0 114]
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For example, CSJ-RSs may be grouped for each neighbor base station 300.
According to the grouping, the CSI-RSs of the neighbor base station 300 are received
by !MRs that are different for each neighbor base station 300. In this manner, the
terminal apparatus' 200 can measure the magnitude of the interference for each
5 neighbor base station 300 and request suppression of the inte1ference for each
neighbor base station 300. In this case, the IMR configuration includes information
that indicates the neighbor base station 300 corresponding to each !MR. In addition,
the IMR assignment information in the second example described above includes
infonnation that indicates the neighbor base station 300 corresponding to each IMR
10 of the base station 100.
[Oll5]
For example, the IMR configuration may include information that indicates
a Pc corresponding to at least a part of!MRs. That is, the information that indicates
the PC corresponding to a part of !MRs may be omitted. For an IMR with a Pc of 0
15 d B or a vicinity value, for example, the information that indicates the Pc :may be
omitted. This is because the error in the estimation is small in the first place. This
omission enables reduction of the amount of communication for providing the
notification of the IMR configuration.
20
(0116]
For example, the base station 100 (for example, the setting unit 151) may
control whether or.not to provide the notification of the information that indicates the
Pc corresponding .to each IMR to the tenninal apparatus 200 for each terminal
apparatus 200. The desired signal is more dominant than the interference signal in
relation to the terminal apparatus 200 that is located near the base station 100, for
25 example. Therefore, since whether or not to con·ect the error in the estimation by
. using the Pc has less influences on the SINR and the CQI, the notification and the
correction of the error in the estimation may be omitted. Specifically, the base
station 100 (for example, the setting unit 151) may omit the notification in a case in
which the sum of the entire interference power measured in all the !MRs set for the
30 terminal apparatus 200 is equal to or less than a threshold value (about -110 dB, for
example). In this case, the information that indicates the sum of the interference
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power is fed back from the terminal apparatus 200 to the base station I 00. The
information that indicates the sum of the interference power may be an \index of I 0 if
the interference power is -I 00 dBm or an index of 9 if the interference power is -90
dBm, for example. Hereinafter, an example of a flow of the processing will be
5 described with reference to FIG. 12.
[0117]
FIG. 12 is a sequence diagram illustrating an example of a flow of
processing of detennining whether or not to provide a notification of the information
that indicates a Pc corresponding to each IMR that is executed in the system I
10 according to the embodiment. As illustrated in FIG. 12, the base station I 00
transmits the CSI-RS configuration to the terminal apparatus 200 (Step S302) and
transmits the CSI-RS to the terminal apparatus 200 (Step S304). Next, the base
station I 00 transmits a part of the IMR configuration (the information that indicates a
Pc corresponding to the IMR is excluded; for example, the information that indicates
15 the position and the cycle of the IMR is included) to the tenninal apparatus 200 (Step
S306). Next, the terminal apparatus 200 calculates the sum of the interference
power (Step S308) and transmits an index of the sum of the interference power to the
base station 100 (Step S31 0). Then, the base station 100 determines whether or not
the interference from the neighbor base station 300 is problematic, on the basis of
20 whether or not the sum of the interference power indicated by the index is equal to or
less than the threshold value, for example (Step S312). In a case: in which it is
determined that the interference is problematic (in a case in which the sum exceeds
the threshold value, for example), the base station 100 provides a notification of a
message of an instruction for correcting the error in the estimation by using the Pc to
25 the terminal! apparatus 200 (Step S314). This message includes the information that
indicates the Pc cotTesponding to the !MR. Meanwhile, in a case in which it is
determined that the interference is not problematic (in a case in which the sum is
equal to or less than the threshold value, for example), the base station 100 omits the
notification of the message of the instruction for correcting the erroring the
30 estimation by using the Pc.
[0 118]
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' Note that these variations may be appropriately combined. For example,
the CSI-RSs may be grouped for each neighbor base station 300 for the neighbor
base stations 300 near the terminal apparatus 200, and the correction of the error in
the estimation may be omitted for the neighbor base stations 300 far from the
5 terminal apparatus 200.
[0119]
<<4. Second embodiment>>
Next, a second embodiment will be described with reference to FIGS. 13 to
16.
10 (0120]
<4. I. Technical problems>
Whether or not the POSCH is actually used greatly affects the amount of
interference. In the first embodiment, the received power of the interference data
signal is estimated on the assumption that the data signal is trausmilted from the
15 neighbor base station 300. Therefore, a large error in the estimation can occur in
the estimation method according to the first embodiment in a case in which the data
signal is not transmitted from the neighbor base station 300.
(0121]
Here, if the schedule infonnation related to the frequency, the time, the
20 beam, and the like of the POSCH transmitted from the neighbor base station 300 is
ascertained, it is considered to be possible to correct this error in the estimation.
However, since the downlink assignment corresponding to the .schedule information
in the LTE in the related art has a large amount of information and instantaneously
provides a notification of the most recent schedule to the terminal apparatus under
25 control, the downlink assignment is not suitable for the purpose of sharing the
information with other base stations. In addition, although a .method of correcting
the estimated value of the interference power on the basis of the schedule
information from the neighbor base station 300 on the side of the base station I 00 is
also considered, overhead of uplink communication for feeding back the estimated
30 value of the interference power is problematic in this method.
[0122]
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<4.2. Technical features>
(1) Use of schedule information
In the embodiment, schedule information that indicates a rough transmission
'schedule with reduced granularity as compared with that in the related art. More
5 specifically, the schedule information according to the embodiment is information
that indicates restriction of a transmission schedule of the data signal in the neighbor
base station 300 in a predetermined period of time in the future. The restriction of
the transmission schedule in the predetermined period of time in the future can also
be stated as prediction of the transmission schedule.
10 . [0123]
A method of reducing the granularity in a frequency direction is exemplified
• .as the method of reducing the granularity while the UE1to be used is scheduled for
';each resource block that includes twelve sub-carriers and seven OFDM symbols in
i the LTE in the related art, for example. For example, tHe schedule information may
15 · include information that indicates whether or not each sub-band is used for
, transmitting the data signal. The sub-band can also be understood as a frequency
band that includes a plurality of sub-carriers or a frequency band that is obtained by
dividing a component carrier to a plurality of parts. In addition, the schedule
information may include information that indicates whether or not each beam is used
20 :to transmit the data signal. Note that the information that indicates whether or not
• ,the sub-band is used to transmit the data signal can also be understood as information
that indicates a sub-band that is used with a high possibility. The same applies to
. beams.
[0124]
25 1 The base station 100 (for example, the setting unit 151) acqu1res the
schedule information (that is, the aforementioned information that indicates the
·.rough transmission schedule) in the neighbor base station 300. Then, the base
station 100 (for example, the setting unit 151) provides a notification of the acquired
·schedule information to the terminal apparatus 200. The schedule information may
30 be included in the IMR configuration.
[0125]
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The tetminal apparatus 200 (for example,the acquisition unit 241) acquires
the schedule information from the base station I 00. Then, the terminal apparatus
200 (for example, the measurement unit 243) futther estimates received power of the
interference data signal for each sub-band on the basis of the schedule information.
5 Specifically, the terminal apparatus 200 performs the estimation by the method
described in the first embodiment for the sub-band to be used and performs the
estimation on the assumption that the received power is zero or a small value for the
sub-band that is not used. Then, the terminal apparatus 200 calculates the CQI for
each sub-band and feeds back the CQl. An example of the schedule information is
10 illustrated in FIG. 13. As illustrated in FIG. 13, the schedule information includes
information that indicates whether or not each interference beam (the POSCH with
beam forming) is used for each sub-band. For example, the terminal apparatus 200
calculates the CQI of the entire bandwidth (for example, the width of 20 MHz) in
consideration only of N sub-bands that are used1with a high possibility among M
15 sub-bands as the interference power in relation· to an interference beam #I. If
description is given while focusing on a sub-band #3, the terminal apparatus 200
separately measures interference power of four interference beams (CSI-RS with
beam forming) by using four IMRs, then refers to the schedule information for each
sub-band, and calculates the CQI in consideration only of the interference power of
, 20 the interference beams #2, #3, and #4.
[0126]
Hereinafter, an example of a flow of processing calculating the CQI by the
terminal apparatus 200 according to the embodiment will be described with reference
to FIG. 14.
25 [0127]
FIG 14 is a flowchart illustrating an example of a flow of processing of
calculating the CQ!l that is executed in the terminal apparatus 200 according to the
embodiment. Processing related to Steps S I 02 to S 114 is as described above with
reference to FIG I 0. After Step S 114, the terminal apparatus 200 (for example, the
30 measurement unit 243) corrects the error in estimated received power by using the
schedule infmmation of the neighbor base station 300 (Step S 116). Then, the
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terminal apparatus 200 (measurement unit 243) calculates the CQI on the basis of
these estimation results (Step S 120).
[0128]
(2) Limitation of sub-band to transmit CSI-RS
5 The LTE is typically run by a component carrier with a bandwidth of 20
MHz, and the CQI is fed back in units of sub-bands obtained by dividing 20 MHz
into M parts. Following this procedure, the terminal apparatus 200 (for example,
the measurement unit 243) according to the embodiment may calculate and feed back
the CQI for each sub-band. The terminal apparatus 200 can also feed back a more
10 accurate CQI for each sub-band in this case by estimating the received power of the
interference data signal on the basis of the schedule information.
[0129]
According to the LTE in the related art, one CSI-RS with beamforming is
transmitted by all resource blocks with the bandwidth (for example, 20 MHz).
15 Meanwhile, the neighbor base station 300 may transmit the CSI-RS only with the
sub-band that is used with a high possibility for the data signal to any of the terminal
apparatuses 200. In this case, the terminal apparatus 200 under the control of the
base station I 00 can estimate the received power of the interference data signal in
consideration only of the sub-band that is used with a high possibility without
20 selecting the sub-band to be considered for estimating the interference power on the
basis of the schedule information. In addition, it is possible to reduce the resource
for transmitting the CSJCRS and to reduce. the IMR set by the base station 100 by
limiting the sub-band in which the neighbor base station 300 transmits the CSI-RS to
a pat1 of the bandwidth. This is because only a smaller number of IMRs are
25 necessary in the case in which the CSI-RS is transmitted only in a part of the
bandwidth than in the case in which the CSI-RS is transmitted in the entire
bandwidth.
[0 130]
The base station I 00 shares the schedule information with the neighbor base
30 station 300 and provides a notification of the shared schedule information to the
terminal apparatus 200. If this is more simply stated, the base station I 00 provides
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a notification of the information that indicates the sub-band that is used with a high
possibility, which is shared with the neighbor base station 300, to the terminal
apparatus 200. In this manner, the tetminal apparatus 200 can reduce processing
burden by performing the measurement only in the sub-band of the notification.
5 The tenninal apparatus 200 can estimate the received power of the interference data
signal in consideration only of the sub-band that is used with a high possibility as
described above even in a case in which the notification of the schedule information
is not provided to the terminal apparatus 200. This is because the CSR-RS is
transmitted only in the sub band that is used with a high possibility from the neighbor
10 base station 300.
[0131]
15
Hereinafter, an example of a flow of processing in the entire system
according to the embodiment will be described with reference to FIG 15.
[0132]
FIG 15 is a sequence diagram illustrating an example of a flow of
measurement report processing that is executed in the system l according to the
embodiment. Processing related to Steps S402 to S406 is similar to the processing
related to Steps S202 to S206 described above with reference to FIG. II. Next, the
base station I 00 and the neighbor base station 300 mutually provide notifications of
20 the schedule information (that is, the information that indicates the sub-band that is
used with high possibility) (Step S408). Next, the base station l 00 provides a
notification of the schedule information to the terminal apparatus 200 (Step S410).
These notification of the schedules may be omitted. Next, the base station 100
transmits the CSI-RS to the terminal apparatus 200 (Step S412). In addition, the
25 neighbor base station 300 transmits ihe CSI-RS to the terminal apparatus 200 in the
sub-band that is used with a high possibility with reference to the schedule
information (Step S414). Then, the terminal apparatus 200 calculates the CQI as
described above with reference to FIG. 14 (Step S416) and feeds back the CQI to the
base station 1 00 (Step S418).
30 [0133]
(3) Setting of IMR corresponding to schedule information
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CSI-RSs of neighbor base stations 300 may be grouped in accordance with
the schedule information. In this manner, the CSI-RS of the neighbor base stations
300 are received by the !MRs of the groups corresponding to the schedule
information ofthe neighbor base stations 300.
5 [0134]
According to the embodiment, the notification of the schedule infonnation
corresponding to each IMR is provided to the terminal apparatus 200. This
information may be included in the IMR configuration. The terminal apparatus 200
can ascertain which IMR the CSI-RS under the control of which transmission
10 schedule will arrive, by the information. An example ofthe schedule information is
illustrated in FIG. 16. As illustrated in FIG. 16, the schedule information includes
information that indicates whether or not each sub-band is used for each scheduling
group (a group of the same or similar schedule information, for example). For
example, a scheduling group #l is a group for which only the sub-bands #2 and #4
15 are used. In addition, a scheduling group #2 is a group for which only the subbands
#3 and #M are used. If description will be given while focusing on the subband
#3, the terminal apparatus 200 separately measures the interference power of
the CSI-RSs from the neighbor base stations 300 that belong to the four groups by
using four IMRs and the calculates the CQl in consideration only of the interference
20 power of the scheduling groups #2, #3, and #4.
[0135)
A flow of processing in a case in which lMRs corresponding to the schedule
information may be similar to that described above with reference to FIG. 15. In
such a case, the notification of the schedule information CO!Tesponding to each IMR
25 is provided to the terminal apparatus 200 in Step S41 0, for example.
(0136]
<<5. Application examples>>
The technique according to the present disclosure is applicable to various
products. ' The base station 100 may also be implemented, for example, as any type
30 of evolved Node B ( eNB) such as macro eNBs and small eNBs. Small eNBs may
cover smaller cells than the macro cells of pico eNBs, micro eNBs, home (femt)
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eNBs, or the like. Instead, the base station I 00 may be implemented as another
type of base station such as Nodes B, base transceiver stations (BTSs), or the like.
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
5 radio heads (RRHs) that are disposed at different locations from that of the main
apparatus. Also, various types of terminals described below may function as the
base station 100 by temporarily or semi-permanently executing the functionality of
the base station. Furthermore, at least some of components of the base station I 00
may be realized in a base station apparatus or a module for a base station apparatus.
10 (0137]
Further, for example, the terminal apparatus 200 may be implemented as a
mobile terminal such as 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. In addition, the terminal
15 apparatus 200 may be implemented as a machine type communication (MTC) for
establishing a machine to machine communication (M2M). Furthermore, at least
some of components of the terminal apparatus 200 may be implemented as a module
(e.g. integrated circuit module constituted with a single die) that is mounted on these
terminals.
20 [0138]
<5. L Application examples for base station>
(First application example)
FIG. 17 is a block diagram illustrating a first example of a schematic
configuration of an eNB to which the technology according to the present disclosure
25 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.
[0139]
Each of the antennas 810 includes a single or a plurality of antenna elements
30 (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
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800 may include the plurality of the antennas 810 as illustrated in FIG. 17, and the
plurality of antennas 810 may, for example, correspond to a plurality of frequency
bands used by the eNB 800. It should be noted that while FIG. 17 illustrates an
example in which :the eNB 800 includes the plurality of antennas 810, the eNB 800
5 may include the single antenna 810.
[0140]
10
The base station apparatus 820 includes a controller 821, a memory 822, a
network interface 823, and a wireless communication interface 825.
[0 141]
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,
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
15 bundling data from a plurality of base band processors to transfer the generated
bundled packet. In addition, the controller 821 may also have a logical function of
performing control such as radio resource control, radio bearer control, mobility
management, admission control, and scheduling. The control may be performed in
cooperation with a surrounding eNB or a core network. In addition, the memory
20 822 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).
[0 142]
The network interface 823 is a communication interface for connecting the
25 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 eNB 800 may be connected to a core network node or another eNB
through a logical interface (e.g. Sl interface or X2 interface). The .network
interface 823 may be a wired communication interface or a wireless communication
30 interface for wireless backhaul. When the network interface 823 is a wireless
communication interface, the network interface 823 may use a higher frequency band
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for wireless communication than a frequency band used by the wireless
communication interface 825.
[0 143]
The wireless communication interface 825 suppot1s a cellular
5 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
the antenna 810. The wireless communication interface 825 may typically include a
base band (BB) processor 826, an RF circuit 827, and the like. The BB processor
826 may,· for example, perform encoding/decoding, modulation/demodulation,
10 multiplexing/demultiplexing, and the like, and performs a variety of signal
processing on each layer (e.g. Ll, medium access control (MAC), radio link control
(RLC), and.packet data convergence protocol (PDCP)). The BB processor 826 may
have part or all of the logical functions as described above instead of the controller
821. The BB processor 826 may be a module including a memory having a
15 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. In addition, the module may be a card or blade to be inserted
into a slot 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 filter, an amplifier,
20 and the like, and transmits and receives a wireless signal via the antenna 810.
(0144]
The wireless communication interface 825 may include a plurality of the BB
processors 826 as illustrated in FIG. 17, and the plurality of BB processors 826 may,
for example, correspond to a plurality of frequency bands used by the eNB 800. In
25 addition, the wireless communication interface 825 may also include a plurality of
the RF circuits 827, as illustrated in FIG. 17, and the plurality ofRF circuits 827 may,
for examp.le, correspond to a plurality of antenna elements. Note that, FIG. 17
illustrates an example in which the wireless communication interface 825 includes
the plurality of BB processors 826 and the plurality of RF circuits 827, but the
30 wireless communication interface 825 may include the single BB .processor 826 or
the single .RF circuit 827.
SP364985WOOO
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[0 145]
In the eNB 800 illustrated in FIG. 17, one or more components included in
the processing unit 150 (the setting unit 151 and/or the communication control unit
153} described above with reference to FIG. 7 may be mounted in the wireless
5 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 communication
interface 825 (for example, the BB processor 826) and/or the controller 821, and the
above-described one or more components may be mounted in the module. In this
10 case, the module may store a program causing the processor to function as the abovedescribed
one or more components (that is, a program causing the processor to
perform the operation of the above-described one or more components) and execute
the program. As another example, the program causing the processor to function as
the above-described one or more components may be installed in the eNB 800, and
15 the :wireless communication interface 825 (for example, the BB processor 826)
and/or the controller 821 may execute the program. As described above, the eNB
800, the base station apparatus 820, or the module may be provided as an apparatus
including the above-described one or more components, and the program causing the
processor to function as the above-described one or more components may be
20 provided. In addition, a readable recording medium in which the program is
recorded may be provided.
[0146]
In addition, in the eNB 800 shown in FIG. 17, the wireless communication
unit; 120 described with reference to FIG. 7 may be implemented by the wireless
25 communication interface 825 (for example, the RF circuit; 827). Moreover, the
antenna unit l I 0 may be implemented by the antenna 810. In addition, the network
communication unit 130 may be implemented by the controller 821 and/or the
network interface 823. In addition, the storage unit 140 may be implemented by the
memory 822.
30 [0147]
(Second application example)
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FIG. 18 is a block diagram illustrating a second example of a schematic
configuration of an eNB to which the technology according to the present disclosure
may be applied. An eNB 830 includes one or more antennas 840, a base station
apparatus 850, and an RRH 860. Each of the antennas 840 and the RRH 860 may
5 be connected to each other via an RF cable. In addition, the base station apparatus
850 and the RRH 860 may be connected to each other by a high speed line such as
optical fiber cables.
[0148]
Each of the antennas 840 includes a single or a;plurality of antenna elements
10 (e.g. plurality of antenna elements constituting a MIMO antenna), and is used for the
RRH 860 to transmit and receive a wireless signal. The eNB 830 may include a
plurality of the antennas 840 as illustrated in FIG 18, and the plurality of antennas
840 may, for example, correspond to a plurality of frequency bands used by the eNB
830. Note that, FIG 18 illustrates an example in which the eNB 830 includes the
15 plurality of antennas 840, but the eNB 830 may include d1e single antenna 840.
[0149]
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
20 are similar to the controller 821, the memory 822, and the network interface 823
described with reference to FIG. 17.
[0150]
The wireless communication interface 85 5 supports a cellular
communication system such as LTE and LTE-Advanced, and provides wireless
25 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
typically include a BB processor 856 and the like. The. BB processor 856 is similar
to the BB processor 826 described with reference to• FIG. I 7 except that the BB
processor 856 is connected to an RF circuit 864 of the RRH 860 via the connection
30 interface 857. The wireless communication interface:855 may include a plurality of
the BB processors 856, as illustrated in FIG. 18, and the plurality of BB processors
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856 may, for example, correspond to a plurality of frequency bands used by the eNB
830 respectively. Note that, FIG. 18 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.
5 [0151]
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
10 communication interface 855) to the RRH 860.
[0152]
Further, the RRH 860 includes a connection interface 861 and a wireless
communication interface 863.
[0153]
· 15 The connection interface 861 is an interface for connecting the RRH 860
(wireless communication interface 863) to the base station apparatus 850. The
connection interface 861 may be a communication module for communication on the
high speed line.
[0154]
20 The wireless communication interface 863 transmits and receives a wireless
signal via the antenna 840. The wireless communication interface 863 may
typically include the RF circuit 864 and the like. 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
25 plurality of the RF circuits 864 as illustrated in FIG. 18, and the plurality of RF
circuits 864 may, for example, correspond to a plurality of antenna elements. Note
that, FIG. 18 illustrates an 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.
30 [0155]
In the eNB 830 illustrated in FIG. 18, one or more components included in
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the processing unit 150 (the setting unit 151 and/or the communication control unit
153) described above with reference to FIG. 7 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.
5 As an example, the eNB 830 may be equipped with a module including some or all
components of the wireless communication interface 855 (for example, the BB
processor 856) and/or the controller 851, and the above-described one or more
components may be mounted in the module. In this case, the module may store a
program causing the processor to function as the above-described one or more
10 components (that is, a program causing the processor to perform the operation of the
above-described one or more components) and execute the program. As another
example, the program causing the processor to function as the above-described one
or more components may be installed · in the eNB 830, and the wireless
communication interface 855 (for example, the BB processor 856) and/or the
15 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
the above-described one or more components, and the program causing the processor
to function as the above-described one or more components may be provided. In
addition, a readable recording medium in which the program is recorded may be
20 provided.
[0156]
In addition, for example, in the eNB 830 shown in FIG. 18, the wireless
communication unit 120 described with reference to FIG. 7 may be implemented by
the wireless communication interface 863 (for example, the RF circuit 864).
25 Moreover, the antenna unit II 0 may be implemented by the antenna 840. In
addition, the network communication unit 130 may be implemented by the controller
851 and/or the network interface 853. In addition, the storage unit 140 may be
implemented by the memory 852.
[0157]
30 <5.2. Application examples for terminal apparatus>
(First application example)
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FIG. 19 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
5 sensor 907, a microphone 908, an input device 909, a display device 910, a speaker
911, a wireless communication interface 912, one or more antenna switches 915, one
or more antennas 916, a bus 917, a battery 918, and a secondary controller 919.
[0158]
The processor 90 I may be, for example, a CPU or a system on chip (SoC),
10 and controls the functions of an application layer and other layers of the smartphone
900. The memory 902 includes a RAM and a ROM, and stores a program executed
by the processor 90 I and data. The,storage 903 may include a storage medium such
as semiconductor memories and hard disks. The external connection interface 904
is an interface for connecting the smartphone 900 to an externally attached device
15 such as memory cards and universal serial bus (USB) devices.
[0159]
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,
20 a positioning sensor, a gyro sensor, a geomagnetic sensor, an acceleration sensor, and
the like. The microphone 908 converts a sound that is input into the smartphone
900 to an 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, a switch, or the like, and accepts an operation or an information
25 input from a user. For example, the display device 910 includes a screen such as
liquid crystal displays (LCDs) and organic light emitting diode (OLEO) displays, and
displays an output image of the smartphone 900. The speaker 911 convetts the
audio signal that is output from the smartphone 900 to a sound.
30
[0 160]
The wireless communication interface 912 supports a cellular
communication system such as LTE or LTE-Advanced, and performs wireless
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communication. The wireless communication interface 912 may typically include
the BB processor 913, the RF circuit 914, and the like. The BB processor 913 may,
for example, perform encoding/decoding, modulation/demodulation,
multiplexing/demultiplexing, and the like, and performs a variety of types of signal
5 processing for wireless communication. On the other hand, the RF circuit 914 may
include a mixer, a filter, an amplifier, and the like, and transmits and receives a
wireless signal via the antenna 916. The wireless communication interface 912 may
be a one-chip module in which the BB processor 913 and the RF circuit 914 are
integrated. The wireless communication interface 912 may include a plurality of
10 BB processors 913 and a plurality ofRF circuits 914 as illustrated in FIG 19. Note
that, FIG 19 illustrates an example in which the wireless communication interface
912 includes a plurality ofBB processors 913 and a plurality ofRF circuits 914, but
the wireless communication interface 912 may include a single BB processor 913 or
a single RF circuit 914.
15 (0161]
Further, the wireless communication interface 912 may support other types
of wireless communication 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
20 wireless communication interface 912 may include the BB processor 913 and the RF
circuit 914 for each wireless communication system.
[0 162]
Each antenna switch 915 switches a connection destination of the antenna
916 among a plurality of circuits (for example, circuits for different wireless
25 communication systems) included in the wireless communication interface 912.
[0163]
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
30 interface 912. The smartphone 900 may include a plurality of antennas 916 as
illustrated in FIG. 19. Note that, FIG. 19 illustrates an example in which the
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smarlphone 900 includes a plurality of antennas 916, but the smartphone 900 may
include a single antenna 916.
[0164]
Further, the smarlphone 900 may include the antenna 916 for each wireless
5 communication system. In this case, the antenna switch 915 may be omitted from a
configuration of the smartphone 900.
[0 I 65]
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
10 microphone 908, the input device 909, the display device 910, the speaker 911, the
wireless communication interface 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. 19 via a feeder line that is partially illustrated in the figure as a
dashed line. The secondary controller 919, for example, operates a minimally
15 necessary function of the smartphone 900 in a sleep mode.
[0 I 66]
In the smartphone 900 illustrated in FIG. 19, one or more components
included in the processing unit 240 (the acquisition unit 24 I and/or the measurement
unit 243) described above with reference to FIG. 8 may be mounted in the wireless
20 communication interface 912. Alternatively, at least some of the components may
be mounted in the processor 901 or the secondary controller 919. As an example,
the smattphone 900 may be equipped with a module including some or all
components of the wireless communication interface 912 (for example, the BB
processor 913), the processor 901, and/or the secondary controller 919, and the
25 above-described one 011 more components may be mounted in the module. In this
case, the module may store a program causing the processor to function as the abovedescribed
one or more components (that is, a program causing the processor. to
perform the operation of the above-described one or more components) and execute
the program. As another example, the program causing the processor to function as
30 the above-described one or more components may be installed in the smartphone 900,
and the wireless communication interface 912 (for example, the BB processor 913),
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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 above-described one or more components, and the program
causing the processor to function as the above-described one or more components
5 may be provided. In addition, a readable recording medium in which the program
is recorded may be provided.
[0167]
In addition, for example, in the smartphone 900 shown in FI>
The embodiment of the present disclosure has been described above in
detail with reference to FIGS. I to 20. As described above, the terminal apparatus
5 feeds back the CQI of the serving base station, which has been calculated on the
basis of the results of measuring the reference signals received from the serving base
station and the neighbor base station and the information related to Pc of the
neighbor base station. In this manner, it becomes possible to feed back the CQI in
consideration of the difference in the received power between the reference signal
10 and the data signal related to the CSI-RS from the neighbor base station and to
perform selection and the like of a more appropriate modulation scheme by the
serving base station.
[0182]
The preferred embodiment(s) of the, present disclosure has/have been
15 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 disclosure.
20 [0183]
For example, the technical features that have been described m the
respective embodiments described above can be appropriately combined.
[0 184]
In addition, the processing described by using the flowchatts and the
25 sequence diagrams in this specification may not necessarily executed in the orders
described in the drawings. Some processing steps may be executed in parallel. In
addition, additional processing steps may be employed, and a part of the processing
steps may be omitted.
[0185]
30 Fmther, the effects described in this specification are merely illustrative or
exemplified effects, and are not limitative. That is, with or in the place of the above
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effects, the technology according to the present disclosure may achieve other effects
that are clear to those skilled in the art fi·om the description of this specification.
[0186]
Additionally, the present technology may also be configured as below.
5 (I)
An apparatus including:
a processing unit that feeds back a channel quality indicator (CQI) of a
serving base station, which is calculated on a basis of results of measuring reference
signals received from the serving base station and a neighbor base station and
10 information related to a power difference between the reference signal and a data
signal of the neighbor base station, to the serving base station.
(2)
The apparatus according to (I),
in which the infonnation related to the difference includes information
15 related to an assumed ratio of an energy •per resource element (EPRE) of the data
signal with respect to an EPRE of the reference signal of the neighbor base station.
(3)
The apparatus according to (2),
in which the information related to the difference includes information that
20 indicates the ratio corresponding to at least a part of an interference measurement
resource (IMR), and
25
the reference signal of the neighbor base station is received by the IMR
corresponding to the ratio of the reference signal.
(4)
The apparatus according to (3),
in which one or more reference signals are received by the !MR.
(5)
The apparatus according to any one of (I) to ( 4),
in which the information related to the difference includes information that
30 indicates a base station corresponding to each IMR, and
the reference signal of the neighbor base station is received by a different
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IMR for each base station.
(6)
The apparatus according to any one of (1) to (5),
in which the information related to the difference includes information that
5 indicates restriction of a transmission schedule of the data signal in the neighbor base
station in a predetermined period of time in future.
(7)
The apparatus according to (6),
in which the information that indicates the restriction of the transmission
10 schedule includes information that indicates whether or not each sub-band is used to
transmit the data signal.
(8)
The apparatus according to (6) or (7),
in which the information that indicates the restriction of the transmission
15 schedule includes information that indicates whether or not each beam is used to
transmit the data signal.
(9)
The apparatus according to any one of ( 6) to (8),
in which the information related to the difference includes information that
20 indicates the restriction of the transmission schedule corresponding to each IMR, and
25
the reference signal of the neighbor base station is received by an IMR
corresponding to the restriction of the transmission schedule of the neighbor base
station.
(10)
The apparatus according to any one of (I) to (9),
in which the reference signal is a channel state information reference signal
(CSI-RS).
(II)
The apparatus according to any one of (I) to (I 0),
30 in which the data signal is a signal that is transmitted through a physical
downlink shared channel (PDSCH).
5
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(12)
The apparatus according to any one of (1) to (II),
in which the reference signal is subjected to beam forming.
(13)
An apparatus including:
a processing unit that provides a notification of information related to a
power difference between a reference signal and a data signal of a neighbor base
station to a terminal apparatus under the control of the apparatus and receives
feedback of a CQI that is calculated on a basis of results of measuring reference
10 signals that are received from a serving base station and the neighbor base station
and information related to the difference from the tenninal apparatus.

CLAIMS
Claim I
An apparatus comprising:
a processing unit that feeds back a channel quality indicator (CQI) of a
5 serving base station, which is calculated on a basis of results of measuring reference
signals received from the serving base station and a neighbor base station and
information related to a power difference between the reference signal and a data
signal of the neighbor base station, to the serving base station.
10 Claim 2
15
The apparatus according to claim I,
wherein the information related to the difference includes information
related to an assumed ratio of an energy per resource element (EPRE) of the data
signal with respect to an EPRE of the reference signal of the neighbor base station.
Claim3
The apparatus according to claim 2,
wherein the information related to the difference includes information that
indicates the ratio corresponding to at least a part of an interference measurement
20 resource (IMR), and
25
30
the reference signal of the neighbor base station is received by the IMR
corresponding to the ratio of the reference signal.
Claim 4
The apparatus according to claim 3,
wherein one or more reference signals are received by the !MR.
Claim 5
The apparatus according to claim 1,
wherein the infonnation related to the difference includes information that
indicates a base station corresponding to each IMR, and
5
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the reference signal of the neighbor base station is' received by a different
IMR for each base station.
Claim 6
The apparatus according to claim I,
wherein the information related to the difference includes information that
indicates restriction of a transmission schedule of the data signal in the neighbor base
station in a predetermined period oftime in future.
10 Claim 7
15
The apparatus according to claim 6,
wherein the information that indicates the restriction of the transmission
schedule includes information that indicates whether or not each sub-band is used to
transmit the data signal.
Claim 8
The apparatus according to claim 6,
wherein the information that indicates the restriction of the transmission
schedule includes information that indicates whether or not each beam is used to
20 transmit the data signal.
Claim 9
The apparatus according to claim 6,
wherein the information related to the difference includes information that
25 indicates the restriction of the transmission schedule corresponding to each IMR, and
the reference signal of the neighbor base station