Description
Title of Invention
COMMUN1CATTON CONTROL DEVICE, COMMUNICATION CONTROL
5 METHOD, AND TERMINAL DEVICE
Technical Field
[0001]
The present disci osure relates lo communication control devices,
10 communication control methods, and terminal devices.
Background Art
[0002[
At present, radio communication systems which are compliant with LTE
15 (j.ong Term Evolution), which is a standard developed by the Third Generation.
Partnership Project (3GPP), have been introduced. Moreover, as a fourth
generation standard for radio communication systems, LTE-Advanecd is being
studied. In radio communication systems compliant with LTR or LTE-Advanced,
frequency-division duplex (FDD) or lime-division duplex (TDD) may be employed.
20 [0003|
In radio communication systems compliant with LIE, FDD is typically
employed. 1DD lias scvciai advantages over ^DD. For example, in FDD, it is
necessary to provide a pair of an uplink frequency band and a downlink frequency
band, while, in TDD, it is necessary to provide a single frequency band. Also, hi
25 FDD, the ratio of uplink communication resources and downlink communication
resources is fixed, while, in i'DD, the ratio of uplink communication resources and
downlink communication resources is variable. Specifically, in TDD, the ratio of
uplink communication resources and downlink communication resources can be
changed by changing the link direction configuration of each sub frame in a radio
ISO frame. Because of such advantages, it is expected that TDD will be increasingly
employed in radio communication systems compliant with LTE or I.TE-Advanced.
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Therefore, various tcehniqucs related to LI"H IDD have been proposed.
[0004]
For example, Patent Literature 3 discloses a technique of shilling the
boundary between a downlink sub-frame and an uplink sub-frame, and
5 communicating with another Home NodeB using a sub-frame between the
boundaries before and after the shifting, thereby achieving radio communication
between Home eNodeBs,
Citation List
10 Patent I.ileralure
[O00SJ
Patent Literature 1: JT2012 10310A
Summary of Invention
15 Technical Prohl em
|0006]
In TDD, the ratio of uplink communication resoui'ees and downlink
communication resources is variable, and therefore, different link direction
configurations may he set for different cells, taking the downlink or uplink traffic
20 rale into account. However, when different Jink direction configurations arc set for
different ceils, related cells may have diiferent link directions in the same sub-frame,
and as a result, interference may occur between the related cells. Lor example,
when a piece of user equipment (UL) which is receiving a downlink signal from an
eNodeB in a cell receives an uplink signal of a UL in a cell adjacent to that cell, the
£5 uplink signal may interfere with the downlink signal. When Ihe link direction
conjuration is dynamically set based on an increase or decrease in the uplink or
downlink traffic rale in each cell in order to further improve ihroughput, it is
considerably difficult to control the interference between cells.
[0007]
30 Therefore, it is desirable to reduce Ihe interference between related cells
while improving throughput in a radio communication system employing TDD,
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Solution to Problem
[0008]
According to the present disclosure, there is provided a communication
5 control device including a radio communication unit which communicates wilh one
or more terminal devices in a cell over a channel in which a link direction is allowed
to be dynamically set lor each sub-frame which is a unit ol" time in radio
communication, and a control unit which controls aJlocation of communication
resources to the terminal device based on the setting of the link direction of the
10 channel and a location of the terminal device in the cell.
[0009]
According to the present disclosure, there is provided a communication
control method including communicating with one or more terminal devices in a ceil
over a channel in which a link direction is allowed to be dynamically set for each
15 sub-frame which is a unit of time in radio communication, and controlling allocation
of communication resources to the terminal device based on the setting of the link
direction of the channel and a location of the terminal device in the cell.
[OfllO]
According to the present disclosure, there is provided a terminal device
20 including a radio communication unit which communicates with a base station in a
cell over a channel in which a link direction is allowed Eo he dynamically set Tor each
sub-frame which is a unit of time in radio communication. The radio
communication unit communicates with the base station according lo allocation of
communication resources to the terminal device itself by the base station based on
2ft Ihc setting of the link direction of the channel and a location of the lenninal device
itself m the cell.
Advantageous Effects of Invention
jOOHj
30 As described above, according to Ihc present disclosure, according to the
communication control device, communication control method, and lenninal device,
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the interference bclwccn related cells can be reduced while improving throughput in
a radio communication system employing TDD.
Brief Description of Drawings
f> [0012]
[FIG 1] FIG I is a diagram for describing an example radio frame formal of TDD,
[FIG 2] FIG 2 is a diagram for describing an example special sub-frame included in
a radio frame of TDD.
[FIG 3] FKL 3 is a diagram for describing an example link direction configuration of
10 each sub-frame in a radio frame of TDD.
[FIG 4] FIG 4 is a diagram for describing example interference in a sub-frame in
which a link direction is different between adjacent cells.
[FIG 5] FIG 5 is a diagram for describing a lirst example interference in a sub-frame
in which a link direction is different between a macroccli and a small cell.
15 [FIG. 6] FIG 6 is a diagram Tor describing a second example interference in a subframe
in which a link direction is different between a macroccli and a small cell.
[FIG 7] FIG 7 is a diagram for outlining a first embodiment
[FIG. 8] FIG 8 is a block diagram showing an example configuration of an cNodcB
according to the first embodiment.
20 [FIG 9] FIG 9 is a block diagram showing an example configuration of a UK
according to the first embodiment.
[FIG 10] FIG 10 is a flowchart showing an example schematic flow of a
communication control process according to the first embodiment.
[FIG 11] FIG 11 is a diagram for outlining a variation of the first embodiment.
25 [FIG !2j FIG 12 is a diagram for describing operations of aneNodeB and a UE in a
small cell.
[FIG 131 FIG 13 is a diagram for describing example selection of sub-frames used hi
communication in a small cell,
[FIG. 14j FIG. 14 is a flowchart showing an example schematic flow of a
30 communication control process according to a variation of (he llrsl embodiment.
[FKi. I5| FIG. 35 is a diagram for outlining a second embodiment.
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|F1G. 16] FIG 16 is a diagram for outlining the second embodiment.
[FIG 17] FIG. 17 is a block diagram showing an example configuration of an
eNodcB according to the second embodiment.
[FIG IS] FIG IS is a flowchart showing an example schematic ilow of a
5 communication control process according lo the second embodiment.
[FIG 19] FIG 19 is a diagram for outlining a third embodiment.
[FIG 20] FIG 20 is a block diagram showing an example configuration of an
eNodcB according to the third embodiment.
[FIG 21] FIG 21 is a flowchart showing an example schematic flow of a
10 communication contra! process according to the third embodiment.
fl'IG. 22] FIG 22 is a diagram for outlining a fourth embodiment,
[FIG 23j FIG 23 is a block diagram showing an example configuration of an
eNodcB according to the fourth embodiment.
[FIG. 24] FIG 24 is a flowchart showing an example schematic Ilow of a
15 communication control process according to the fourth embodiment.
Description of Embodiments
[0033]
Hereinafter, preferred embodiments of (he present invention will be
2(3 described hi detail with reference to the appended drawings. Note that, in this
specification and (he drawings, elements that have substantially the same function
and structure arc denoted with the same reference signs, and repeated explanation is
omitted.
|0014]
25 Nole that a description will be given in the following order.
1. Introduction
\. L General Idea of TDD
1. 2. Technical Problem with TDD
2. Fii"si Embodiment
'60 2, 1. Overview
2. 2. Con figuration ofeNodeB
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2, 3. Configuration ofUE
2. 4. Flow of Process
2, 5. Varialions
3, Second Embodiment
ft 3. 1. Overview
3, 2. Configuration of eNodeB
3. 3. Plow of Process
4. Third Embodiment
4. I. Overview
10 4. 2. Configuration of cNodcB
4. 3. Flow of Process
5.Fourth Embodiment
5. I, Overview
5. 2. Configuration ofcNodeB
15 5. 3, Flow of Process
6. Summary
|00!5j
« l , Introduclion»
Firstly, the general idea of TDD and a technical problem with TDD will be
2U described. Although the general idea and technical problem, and embodiments, will
be described herein using a radio communication system compliant with LIE or
LTE-Advanced as an example, the present disclosure is, oJ'course, nut limited to the
example.
[0016]
25
ihe general idea of TDD will be described with reference to FIGS. 1-3,
[0017J
(TDDinLTE)
hi l,TE, any one of FDD and TDD may be employed. In FDD, an uplink-
30 dedicated frequency band and a downlink-dedicated frequency band are used in the
frequency direction. Also, in i'DD, a format in which a radio frame includes 10
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sub-frames is used in the lime direction. On the other hard, also in TDD, a format
in which a radio frame includes 10 sub-frames is used in the time direction.
However, in TDD, the same frequency band is used for both uplink and downlink
communication. The radio frame formal in TDD will now be mote specifically
5 described with reference to FIG. 1.
[0018]
FIG. 1 is a diagram for describing an example radio frame format of TDD.
Referring to 1TG 1, the radio frame is a unit of time in LTE, which Ms a length of 10
nis. Moreover, one radio frame includes !fl sub-frames. Hie sub-frame is also a
10 unil of time in LTIi, which has a length of i ms. In TDD, the link direction is set
for each sub-frame. For example, in the radio frame of FIG. J, me link direction of
the suh-lrame #0 is set to the downlink direction, and the Jink direction of the subframe
#3 is set to the uplink direction.
[0019]
15 Here, "uplink11 refers to communication from a UE to an eNodeR, and
"downlink" refers to communication from an eNodeR to a 1JF. in FIG. I, D, U;and
S indicate a downlink sub-frame, an uplink sub-frame, and a special sub-frame,
respectively. The special sub-frame will be described below.
[0020J
20 In .radio communication systems compliant with IXF, FDD is typically
employed. However, TDD has several advantages over 1'DD.
J0021]
For example, TDD has an advantage in terms of provision of a frequency
band, in FDD, it is necessary to provide a pair of an uplink li'eyueney band and a
25 downlink frequency band, while, in TDD, it is necessary to provide a single
fiLeqitency band.
[0022]
Also, for example, TDD has an advantage in terms of the ratio of uplink and
downlink. As an example, in FDD, when an uplink frequency band of 20 MHz and
30 a downlink frequency band of 20 MIIz are provided, Hie ratio of uplink
communication lesources and downlink communication resources is fixed to "one to
SF345373WO00
one." On the other hand, in TDD: when a frequency hand of 20 MH/ is provided,
the ratio of uplink communication resources and downlink cojnimmication resources
is variable. Specifically, in TDD, by changing the link direction configuration
(hereinafter referred to as a "TDD configuration'1} of each sub-frame in a radio frame,
5 the ratio of uplink communication resources and downlink communication resources
can be changed.
[0023|
Because of such advances, it is expected thai TDD will be increasingly
used in radio commiiEucation systems compliant with LIE or LTE-Advanced.
10 [00241
Although TDD has the above advantages, it is necessary to allocate a period
of time for switching between downlink and uplink. Therefore, hi TDD, a special
sub-frame is inserted between a downlink sub-frame and an uplink sub-frame. The
special sub-frame will now be more specifically described with reference to FIG. 2.
15 [0025]
FIG 2 is a diagram for describing an example of the special sub-frame
included in the radio frame of TDD. Referring to FIG 2, Ihe sub-frames #0-#2 of
the radio frame of FIG. J arc shown. Here, the sub-frame #0 is a downlink subframe,
the sub-lraine #1 is a special siib-fraine, and the sub-frame #2 is an uplink
20 sub-lrame, For an eNodcB, time when a UF receives Ihc downlink signal of the
sub-frame ffO is caused to be later than the time of the sub-frame #0 in the format due
to a transmission delay in space and a piucess delay in the UFL. Also, in order to
cause data lo arrive at the eNodcli at the time of the sub-frame #2 in the format, the
UE needs to transmit an uplink signal in advance. Therefore, the special sub-frame
2G is defined as a region for allocating a period of time corresponding to the delay of
downlink and a period of lime by which uplink is advanced. Specifically, (he
special sub-frame includes a downlink pilot time slot (DwPTS) and an uplink pilot
time slot (UpPTS), Also, Ihe special sub-frame further includes a guard period.
Thus, TDD has the disadvantage that a special sub-frame is inserted during switching
30 between downlink and uplink.
|0026|
9/56
(Specific TDD Configuration)
LTE TDD is defined in 3GPP Release 8. In "TS 36. 211 Table 4. 2-2:
Uplink-Downlink configurations," the link direction configuration {i.e., the TDD
configuration) of each sub-frame in the radio frame of TDD is shown. The TDD
5 configuration will now be more specifically described with reference to FIG 3.
L0027J
FIG 3 is a diagram for describing an example of the link direction
configuration of each sub-frame in the radio frame of TDD. Referring to I'KL 3, in
3GPP, seven TDD configurations, i,e., configurations 0-6, are defined. As
10 described above, in LTH. TDD, the radio frame includes 10 sub-frames, and the link
direction is set for each sub-frame. In the sub-frames #0 and #5 of the 10 subframes,
a synchronization signal is Imnsmitted from an eNodcB, and therefore, the
link directions of the sub-frames #0 and U5 arc invariably fixed to the downlink
direction. Moreover, the sub-frame #1 is a special sub-fiame in any TDD
15 configuration. Also, the link direction of me sub-frame #2 is fixedly set to the
uplink direction. On the other hand, the sub-frame #6 is either a special sub-frame
or a downlink sub-frame. The link directions of the sub-frames #3; M. U7, UK, and
#9 arc set to cither the uplink direction or the downlink direction.
[0028]
20 Jl is typically supposed that each operator selects and uses any one of the
seven TDD configurations. Therefore, for example, it is not supposed thai each
operator sets different TDD configurations for adjacent celts.
[0029]
<1.2. Technical Problem with TDD>
25 Next, a technical problem with TDD will be described with reference (o
FIGS, 4-6,
[0030]
(Example Specific Interference)
In the 3GPP Plenary Meetings held in Kansas City in March 2011, a
,10 decision was made to study the interference problem by setting different TDD
configurations for adjacenf celts. As a result, in LTF. TDD, Ihe general trend has
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been toward setting of different TDD configurations for related cells (e.g., adjacent
cells). Specific interference which occurs when different TDD configurations are
set for related cells (e.g., for adjacent cells, or for a macrocell and a small cell) will
now be more speei fically described with reference to FIGS, 4-fi.
5 [0031 j
FIG. 4 is a diagram Ibf describing example interference in a sub-frame in
which the fink direction Is different between adjacent cells. Referring to i'lG 4, a
cell 10a and a cell 10b adjacent to the cell 10a are shown. Also, in the cell 10a,
there are an eNodcB I la and a UK 21a. In the cell 30b; there arc an cNodeB lib
10 and a ULL 21b. Here, it is assumed ttiat, in some sub-frame, the link direction is the
downlink direction in ihe cell IOJL while the link direction is the uplink direction in
the cell 10b. In this case, when the Uli 21 a which is receiving a downlink signal 13
from the eNodeB 11a in the cell 10a receives an uplink signal 23 from the IIF 21b in
the cell 10b, the uplink signal 23 may interfere with the downlink signal 13. Also,
IS when the cNodeB l ib which is receiving the uplink signal 23 Horn Ihe IJE 21b in the
cell 10b receives the downlink signal 13 from the eNodcB Ma in the cell !0a, the
downlink signal 13 may interfere with the uplink signal 23. Specifically, the
interfering signals are indicated by a dolled line in FIG 4.
[0032]
20 FIG 5 is a diagram lor describing a first example of Ihe interference in a
sub-frame in which the link direction is different lictwccn a macrocell and a small
cell. Referring to FIG. 5, a macrocell 30 and a smalt celt 40 are shown. The
maci'oeeH 30 covers all or part of the small cell 40. Also, in the macrocell 30, there
arcancNodeB31 and a UK 21c, In the small cell 40, there are an eNodeB 41 and a
25 IIF. 21 d. Here, it is assumed that, in some sub-frame, the link direction is the
downlink direction in the macrocell 30, and the link direction is the uplink direction
in Ihe small cell 40. In this case, when (he liR 21c which is receiving a downlink
signal 33 from the eNodeB 31 in the macrocell 30 receives an uplink signal 25 from
the UK 2ld in the small cell 40b, Ihe uplink signal 25 may interfere with the
i!0 downlink signal 33. Also, when the eNodeB 41 which is receiving the uplink signal
25 from the Uli 21d in the smalt cell 40 receives the downlink signal 33 from the
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eNodeB 3 I in the macroccll 30, the downlink signal 33 may interfere with the uplink
signal 25. Specifically, also in FIG. 5, the interfering signals are indicated by a
doited line,
[0033|
5 FIG 6 is a diagram for describing a second example of the interference in a
sub-frarnc in which the fink direction is different between a macroccll and a small
cclh Referring to FIG 6, similar fo FIG 5, a maerocell 30 and a small cell 40 are
shown. Also, an cNodcB 31, a UE 21c, an eNodeB 41, and a ULL 21 d arc shown.
Here, it is assumed that, in some sub-frame, the link direction is the uplink direction
10 in the maerocell 30r and the link direction is the downlink direction in the small cell
40, In this case, when the Uli 2 Id which is receiving a downlink signal 43 from the
cNodeB 41 in the small cell 40 receives an uplink signal 27 from the UR 21c in the
maerocell 30, the uplink: signal 27 may interfere with the downlink signal 43. Also,
when the cNodcB 31 which is receiving the uplink signal 27 front the UE 21c in the
15 maerocell 30 receives the downlink signal 43 from the cNodcB 4! in the small cell
40, the downlink signal 43 may interfere with the uplink signal 27. Specifically,
also in FIG 6, the interfering signals are indicated by a dolled line.
10034J
Note thai the concept of the small cell 40 encompasses a femlocell, nanoeell,
20 picocell, microccH, etc. Ilie small cell 40, which is a supplemental cell for
increasing the comiuimicalion capacity of the maerocell 30, may he introduced by
providing an cNodcB which is smaller than thai of a macroccll.
|00351
(Dynamic Change in TDD Configuration)
2& As described above, interference may occur between related cells when
different TDD configurations ait set for the relaled cells, and on the other hand, it is
desirable that a TDD configuration should be dynamically set for each cell. This is
because an improvement in Ibroughput can be expected by selecting a suitable TDD
configuration based on the uplink or downlink traffic rate in each cell Specifically,
30 when the uplink traffic rate increases in a cell, a TDD configuration including a
larger number of uplink sub-frames should be selected based on the increase in Ihe
3P345378WOO0
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traffic rate. Also, when the downlink traffic rale increases in a cell, a TDD
configuration including a larger number of downlink sub-frames should be selected
based on the increase in the traffic rate. The characteristics of the traffic rate vary
among cells, and therefore, it is desirable thai a TDD configuration should be
5 dynamically set for each cell separately For example, because the radio frame has
a length of 10 ITJS, a TDD configuration may be set every 10 ms So several tens of
milliseconds,
10036]
(Technical Problem)
10 As described above, interference may occur between related cells when
different TDD configurations are set for the related cells, and on the other hand, it is
desirable that the link direction TDD configuration should be dynamically set in
order to improve throughput. However, when the TDD conliguralion is
dynamically set for each cell (e,g.., every several tens of milliseconds), it is
15 considerably difficult to control the interference between cells.
[0037]
lliercforc, in this embodiment, in a radio communication system employing
TDD, the interference between related cells (e.g., between adjacent cells or between
a niaeroeell and a smaJl cell) can he reduced while improving throughput. In the
20 description that follows, specific examples will be given in <2. First Embodiment^
<3, Second Rmbodimcnt>, <4. ihird Embodiment^ and <5. Fourth Embodiment^.
[0038|
« 2 . First Embodiment»
<2. 1. Overview>
25 Firstly, a first embodiment of the present disclosure will be described. In
Ibc lirst embodiment, the link direction is dynamically set for each sub-frame of a
first frequency band. The link direction is set for each sub-frame of a second
frequency band so that the difference in Jink direction between adjacent cells is
reduced, Le,s as lai'ge a number of sub-frames as possible have the same link
30 direction. And, communication resources of the first frequency band are not
allocated to a terminal device located in a peripheral portion of a ceil. The first
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embodiment will now be more specifically outlined with respect lo FIG 7.
[0039]
FIG. 7 is a diagram for outlining the first embodiment. Referring to FIG 7,
a cell 10a and a cell 10b adjacent to The cell 10a are shown, Tn Ibis embodiment, the
5 cell 10 is divided into a peripheral portion which is further from an cNodcB 100-1
and a central portion (i.e., a central portion closer to the eNodeB 100-1) other than
the peripheral poriion. In the centml portion of the eel! 10, the TDD configuration
is dynamically set. On the other hand, in the peripheral portion of the cell 10, the
TDD configuration is set lo be equal or similar lo that of an adjacent cell. Here, the
10 TDD configuration which is simitar to that of an adjacent cell means a TDD
configuration in which the number of sub-frames which have a link direction
different from that of the configuration of the adjacent cell is small. For example,
the configuration 3 and the configuration 4 of FIG 3 have the same link directions in
the sub-frames, except for the sub-frame #4, and therefore, can be said to be similar
15 to each other. Also, for example, in the peripheral portion of the cell 10, the TDD
configuration may be statically or quasi-statically set,
[0040]
in typical LTE, different TDD configurations cannot be used tn a single
frequency band (i.e., a single component carrier (CC) of 20 MHz), and therefore, the
20 carrier aggregation technique is used. Carrier aggregation is a technique of
aggregating a plurality of CCs, thereby improving total throughput. For example,
when the plurality of CCs include a CC i and a CC 2, the CC 1 is used as
communication resources for a UE 200 which is located in the central portion of the
cell 10, and the CC 2 is used as communication resources for a UR 200 which is
25 located in the peripheral portion (and the central portion) of the cell 10. For the CC
1, the TDD configuration is dynamically set based on the traffic rate in the cell. For
the CC 2, the TDD configuration is set (e,gr, statically or quasi-statically) to be equal
oi similar to that of an adjacent cell.
|0041]
30 By thus setting the TDD configuration and allocating communication
resources, communication resources ofa frequency band in which the link direction
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is dynamically set are allocated only to a UE 200 which is located in the central
portion of the eell !0, Therefore, as described below, Iransmission power ol" the
communication resources can be reduced. As a result, an uplink signal on the
communication resources dims not substantially interfere with a downlink signal of
5 an adjacent cell.. and a downlink signal on the communication resources docs not
substantially interfere with an uplink, signal of an adjacent cell, Specifically, in a
frequency band in which the link direction is dynamically set, interference such as
lhat shown in 1'lG 4 does not substantially occur. Note that only communication
resources of a frequency band in which the deference in link direction from an
10 adjacent cell is small arc allocated to a Uli 200 which is located in the peripheral
portion of the cell 10, Therefore, of course, in the frequency band, inierference
such as that shown in 1'lG. 4 docs not substantially occur. Therefore, in a radio
communication system employing TDD, by dynamically setting the link direction,
interference belween adjacent cells can be reduced while improving throughpul.
lf> [0042|
Note that the eNodeB 3 00 1 allocates small transmission power (e.g., power
\) to downlink in the CC l3 and large transmission power (e.g., power 2) to downlink
in the CC 2. Also, the eNodeB 100-1 allocates small transmission power (e.g., (be
power 1) to uplink in thcCC 1 for a UE200 which is located in the central portion of
20 the cell 10 and for which communication resources of the CC I are allocated to
uplink. Also, the eNodeB 100-1 allocates large transmission power (e.g., the power
2) to uplink in the CC 2 for a UE 200 which is located in the peripheral portion of the
cell 10 and lor which communication resources of the CC 2 are allocated to uplink.
This is because transmission power may be small when the distance belween the
25 eNodeB 100-1 and a UK 200 is small, and transmission power needs to be large
when Ihc distance is large. The allocation of the power makes it difficult for a
downlink signal and uplink signal of Ihe CC 1 lor Ihc central portion of the cell 10a
lo reach the central portion of the adjacent cell 10b. Therefore, as described above,
the interference which occult because ditterent TDD configurations am dynamically
30 set for different cells is reduced.
[0043]
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<2. 2. Configuration of eNodeB>
An example con figuration of the eNodeB 100-1 of (he first embodiment will
be described with reference to FIG 8. TIG. 8 is a block diagram showing the
example configuration of the eNodeB 100-1 of the first embodiment. Referring to
5 FIG 8, the eNodeB 100-1 includes a radio communication unit HO, a network
communication unit 120, a storage unit 130, and a processing unit 140.
[0044]
(Radio Communication Unit 110)
The radio communication unit 110 communicates with one or more URs
10 200 in the cell 10 over a clianncl En which the link direction can be dynamically set
for each sub-frame which is a unit of time in radio eommunicalion. The channel
includes, Tor example, at least a first frequency band and a second frequency band.
The first frequency band and the second frequency band are each a component earner.
Specifically, the Fadio communication unit 110 communicates with a UK 200 in Ihe
Ifi eetl 10 on the CC 1 and CC 2 in which the link direction can be dynamically set for
each sub-frame. Also, the radio commumcalion unit 110 transmits a downlink
signal to a UR 200 in the ceil 10 and receives an uplink signal from a Uli 200 in the
cell 10 according to allocation of resources. Note that (he radio communication unit
110 includes, for example, an antenna and an RF circuit.
20 |0045|
(Network Communication Unit 120)
ilic network communication unit 120 communicates with communication
nodes including other eNodeBs, For example, the X2 interface between cNodcBs
may be implemented via the network communication unit 120. The network
25 communication unit 120 may include a radio communication module which may be
shared by the radio communication unit 110, or a wired communication module, such
as a LAN-connected terminal etc.
[004f>|
(Storage Unit 130)
30 The storage unit 330 stores a program and data for operation of the eNodeB
100-1. The storage unit 130 includes, for example, a medium, such as a hard disk, a
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semiconductor memory, etc.
J0047]
(Processing Unit 140)
The processing unit 140 provides various functions of the cNodcB 100-1.
5 For example, the processing unit 140, which corresponds to a processor, such as a
CPU (Central Processing Unit), a DSP (Digital Signal Processor), etc., executes a
program stored in the storage unit 130 or another storage medium to provide the
various Junctions. the processing unit 140 includes a terminal location
measurement unit 141, a traffic rate measurement unit 143, a link direction setting
10 unit 145, a resource control unit 147, and a power control unit 149.
[0048|
(Terminal Location Measurement Unit 141)
The terminal location measurement unit L41 measures a location of a Uli
200 in the cell 10.. The location is, for example, represented by a distance between
15 the eNodeB 100-1 and the UK 2(H). For examplc; Ehc terminal location
measurement unit 141 measures the distance between the eNodeB 100-i and the UE
200 based on a timing advance value For each UE 200,
1(304*3 i
(Traffic Rate Measurement Unit 143)
20 The traffic rate measurement unit 143 measures an uplink traffic rate and a
downlink traffic rale in the cell 10. The traffic rate measurement unit 143 may
measure an actual value of the traffic rate during a predetermined period of time, or
may measure an estimated value of the traffic rate which is predicted to occur during
a predetermined period of time based on a scheduling request from a UE 200 etc.
25 AJso, the traffic rate measurement unit 143 may measure the traffic rate in (he
peripheral portion of the cell 10 and the traffic rale in the central portion of the cell
10 separately, or measure the overall traffic rate without distinguishing between these
transfer rates.
[00501
30 (Link Direction Setting Unit 145)
The link direction setting unit 145 dynamically sets the fink direction lor
SP!M5S73WO00
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each sub-frame of the first frequency band, and sets the link direction lor each subframe
of the second frequency band so lhat the difference in link direction between
the cell 10 and a cell related to the cell 10 is reduced- In this embodiment, the
related ceil is a cell adjacent to the cell 10. For example, the link direction selling
G unit 145 dynamically sets the TDD con figuration of the CC ! based on the uplink or
downlink traffic ralfc. As an example, the TDD configuration of the CC 1 Is set
every 10 ms to several tens of milliseconds. Also, the link direction setting unit 145
sets the TDD configuration of the CC 2 to be equal or similar to the TDD
configuration of the CC 2 of an adjacent cell. As an example, the link direction
10 setting unit 145 negotiates with the eNodeli 100-1 of fhe adjacent cell, through the
network communication unit 120, as to the setting of the link direction of the CC 2,
based on the measured traffic rate. The interface between the cNodcB 100-1 of the
cell lOandtheeNodeB 100-1 of the adjacent cell is the X2 interface,
100511
15 Also, the link direction setting unit 145 statically or quasi-statieally sets the
link direction for each sub-frame of the second frequency band. For example, the
link direction setting unit 145 statically or quasi-statically sels the TDD configuration
of Ihc CC 2. As an example, the link direction setting unit 145 sets die TDD
configuration of the CC 2 each time a predetermined period of time has passed.
20 The predetermined period of time is longer than the interval of the setting of the CC
I. By thus setting statically or quasi-statically, the communication and process for
adjusting the TDD configuration between cNodeBs can be minimized.
(00521
(Resource Control" Unit 147)
?J> The resource control unit 147 controls allocation of communication
resources to a UE 200 based on Ihc setting of the link direction of the channel in
which the link direction can be dynamically set for each sub frame, and the location
of Ihe UK 200 in the cell 10. In particular, in this embodiment, the resource control
unit 147 does nol allocate communication resources of the first frequency band to a
30 UE 200 which is located in the peripheral portion of ihc cell 10, For example, the
resource control unit 147 does not allocate communication, resources of the CC 1 to a
SP34r>373WO00
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UK 200 which is located in the peripheral portion of the cell 10, and allocates
communication resources of the CC 1 to a UE 200 which is not located in the
peripheral portion of the cell 10 (nc.; a UE 200 which is located in the central portion
of the cell 10), Also, for example, the resource control unit 147 allocates
5 communication resources (,V the CC 2 to a UE 200 which is located in the peripheral
portion of the cell 10 (and the central portion of the cell 10).
[0053]
(Power Cxn\lco\ Unit 3 49)
The power control unit 149 controls transmission power in the cell 30. For
10 example, the power control unit 149 controls transmission power of the radio
com muni cation unit 110. 1'or example, the power contro] unit 149 allocates small
transmission power to downlink in the first frequency hand (e,g.., the CC 1), and
large transmission power to downlink in the second frequency band (e.g., the CC 2).
[0054]
15 Also, for example, the eNodeB 3 00— I allocates small transmission power to
uplink in the first frequency band for a Uli 200 which is located in the central portion
of the cell 10 and lor which communication resources of the Ural frequency band
(e.g., the CC 1) arc allocated to uplink. Also, the eNodeB 100-1 allocates large
transmission power to uplink in the second frequency band for a UE 200 which is
20 located in the peripheral portion of the cell It) and for which communication
resources of the second frequency band (e.g., the CC 2) are allocated to uplink,
10O55J
<2. 3. Configuration of UF>
An example configuration of the UE 200 of the first embodiment will be
25 described with reference to FIG 9. FIG. 9 is a block diagram showing the example
eonfiguralion of the UE 200 of the first embodiment Referring to I'iG 9, the UE
200 includes a radio communication unit 210, a storage unit 220, and a processing
unit 230.
fO0561
30 (Radio Communication Unit 210)
The radio communication unit 210 communicates with the eNodeB 100-1 in
SP345373WO00
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the cell 10 over a channel in which the link direction can be dynamically set for each
sub-frame which is a unit of time in radio communication. Also, the radio
communication unit 210 communicates wHh the eNodcB 100-1 according to
allocation of communication resources to the radio communication unit 210 itself
5 which is performed by the cNodeB 100-1 based on the setting of the link direction of
the channel and the location of the radio communication unit 230 itself in the cell 10.
|0057]
For example, the channel includes at least a first frequency band and a
second frequency band. And, the first frequency band and the second frequency
10 band are each a component canier. Specifically, the radio communication unit 210
communicates with the cNodeB 100-3 in the cell 10 on the CC 1 and CC 2 in winch
the link direction can be dynamically set for each sub frame. Also, Ihe sNodeB
100-1 allocates communication resources to the UH 200 based on the settings of the
TDD configurations of the CC 1 and CC 2 and the location of the UE 200 in the cell
15 10, and therefore, the radio communication unit 210 communicates according to the
allocation of communication resources. rJotc that the radio communication unit 110
includes, for example, an antenna and an RF circuit,
[005RJ
(Storage Unit 220)
20 The storage unit 220 stores a program and data for operation of the Uli 200.
l l i c storage unit 220 includes a storage medium, such as a hard disk, a
semiconductor memory, etc.
[0059|
(Processing l]nit 230)
£5 The processing unit 230 provides various functions of the UE 200, For
example, the processing unit 230, which coiresptinds to a processor, such as a CPU
(Central Processing Unit), a DSP (Digital Signal Processor), etc., executes a program
stored in the storage unit 220 or another storage medium to provide the various
functions. As an example, the processing unit 230 controls communication of the
30 radio communication unit 210.
!0060|
SP345373WOO0
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l*or example, the processing unit 230 obtains system information from a
downlink signal received by the radio communication unit 210. A3so5 the
processing unit 230 recognizes the- TDD configuration which has b^en set from Ihc
system information. J*or example, system information of each CC is obtained from
5 the downlinic signal of the CC, and the TDD configuration of each CC is recognized
from the system information of the CC. Thereafter, the processing unit 230 causes
the radio communication unit 210 to communicate based on the recognized TDD
configurations.
[0061]
10 Also, for example, the processing unit 230 obtains scheduling information
of uplink and downlink from a downlink signal received by the radio communication
unit 210, Also, the processing unit 230 recognizes allocation of communication
resources to the UR 200 from the scheduling information. Thereafter, the
processing unit 230 causes the radio communication unit 210 to communicate
15 according to the allocation of communication resources.
[0062]
<2. 4. Mow of Process>
Next, an example communication control process according to the first
embodiment will be described with reference to FIG 10. FIG. 10 is a llowchart
20 showing an example schematic flow of the communication control process of the
first embodiment. Note that the communication control process is a process in Ihc
eNodcBlOO-L
[0063]
Initially, in step S5013 the terminal location measurement unit 141 measures
25 the location of a Uli 200 in the ceil 10, In step S503, the traffic rate measurement
uni( 143 measures the uplink (rattle rate and the downlink traffic rate in the cell 10.
Thereafter, in step S505, the link direction selling unit 145 sets me link direction (e.g.,
Ihc TDD configuration) of IhcCC I based on the measured traffic rales.
[0064]
,10 In step S507: (he link direction setting unit 145 determines whether or not a
predetermined period of time has passed, IT the predetermined period ol' time has
SP34537c!WO00
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passed, control proceeds to step S509. Otherwise, control proceeds lo step S513.
[0065]
In step S509, the link direction setting unit 145 negotiates with the eNodcB
100-1 of an adjacent cell, through Ihe network communication unit 120, as to the
5 setting of the link direction of the CC 2, based on the measured traffic rates.
Thereafter, instep S51I, ihe link direction setting unit 145 sets the link direction (i.e.,
the TDD configuration) of the CC 2 based on the result of the negotiation with the
eNodeR 100-1 of the adjacent cell.
[0066]
10 In step S513s the resource control unit 147 allocates communication
resources of the CC 2 to a LIE 200 which is located in the peripheral portion of the
cell 10 (and the centra! portion of the cell 10). In step S515, the resource control
unit 147 allocates communication resources of the CC 3 to a UK 200 which is not
located in the peripheral portion of the cell 10 (i.e., a UE 200 which is located in the
15 central portion of the cell 10).
J0067]
In step S517, the radio communication unit 110 communicates with the UE
200 using the allocated communication resources.
[0068]
SO <2. 5. Variations>
(1) Overview
Next, a variation of the first embodiment will be described. In this
variation, the cell 10 ts a maerocell which covers all or part of a small cell, ihe
eNodcB 100-1 causes a communication node (e.c,, an eNodeB) of the small cell to
25 set the link direction f the TDD configuration of the CC 1 of the cell JO.
[0071]
By thus setting the TDD configuration, the link direction ol" the cell 10
15 which is a macrocell is equal to the link direction of the small cell 40 in most of the
sub-frames. Therefore, the interference described with reference to FIGS, 5 and 6
can be reduced.
[0072J
(Variation of Small Cell)
20 Note that, similar to the cell 10, the small cell 40 may be divided into a
peripheral porlion which is lurlher from the eNodeB 41 and a ceniral portion (i.e., a
central portion closer to the cNodcB 41) other than the peripheral portion. Ibis will
now be more specifically described with reference to FIG 12.
[0073]
2fi 1TG 12 is a diagram for describing operations of the eNodeB 41 and a UR
200 m the small celt 40. Referring to FIG 3 2, the small cells 40a and 40b shown in
FIG. 11 are also shown. Tn this case, the eNodeB 41a of the small cell 40a
dynamically sets the link direction for each sub-frame of a CC which is different
from the CC 2, and does not allocate communication resources of the different
30 Jrequeney band to an Uli 200c which is located in the peripheral portion of the small
ceil 40a. The eNodeB 41a allocates communication resources ol" the different
spaiaimwooo
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frequency band to a UF, 2001' which is located in the central portion of Ihe small cell
40a, Also, the eNodcB 41b oflhe small cell 40b dynamically sets the link direction
for each sub-frame of a CC other than the CC 15 and does not allocate
communication resources of the different frequency band to a UF. 200g which is
5 located in the peripheral portion of the small cell 40b. The cNodcB 41b allocates
communication resources of the different frequency band to a UE 200h which is
located in the central portion of the small cell 40b.
[0074]
By thus allocating resources, communication resources of a frequency band
10 lor which the link direction is dynamically set (Lc., the different frequency band) are
allocated only to aUE 200 which is located in the central portion oflhe small cell 4flr
Therefore, in the small cell, transmission power of the communication resources can
be reduced. As a result, an nphnk signal on the communication resources of ihe
small cell does not.substantially interfere with a downlink signal of the cell 10, and a
15 downlink signal on the communication resources of the small cell does not
substantially interfere with an uplink signal of ihe maeroecIL Specifically, in a
frequency band for which the link direction is dynamically set. interference of a
small cell with a macrocell, such as those shown in FIGS. 5 and 6, does not
substantially occur.
20 |00751
Moreover, the distance between a UF 200 which is located in the central
portion of the small cell 40, and the cNodcB 41. is smaller than the distance between
theeNodeB 100-1 and the eNodeB 45, and therefore, a downlink signal of the cell, 10
docs not substantially interfere with an uplink signal of the small cell 40. Also, the
25 distance between a UF, 200 which h located in the central portion of the small cell 40,
and the cNodcU 41, is smaller than the distance between the UE 200 and another UE
200 which communicates with Ihe eNodeR 100-1, and therefore, an uplink signal of
the cell 10 docs not substantially interfere with a downlink sipial of the small cell 40,
Specifically, in a frequency band tor which the link direction is dynamically set,
30 interference of a small cell with a macrocell. such as those shown in FIGS. 5 and 6,
does not substantially occur.
sPM5;mwoo<}
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[0076J
Note thai, in the small tell 40, only communication resources of a frequency
band (the CC I or the CC 2) for which the difference in link direction from the cell
10 is small are allocated to a UE 200 which is located in the peripheral porfion of the
5 small cell 40. Therefore, in the frequency band, interference, such as those shown
in FIGS. 5 and 6, does not substantially occur.
[0077]
Therefore, in a radio communication system employing TDD, by
dynamically setting the link direction, interference between a macroccll and a small
10 cell can be reduced while improving throughput.
[007KJ
(2) Configuration ofeNodeR
In this variation, the link direction setting unit 345 and the power control
unit 149 of the eNodeB 100-3 which have been described with reference to FIG. K
15 further operate as follows. Note that, as described above, in tins variation, the cell
10 is a macroccll which covers all or part of the small cell 40.
[0079]
(Link Direction Setting Unit 145)
The link direction setting unit 145 causes the cNodcO 41 in the small cell 40
20 to set the link direction for each sub-frame in the small cell 40 so that the difference
in link direction between the ceil 10 and Ihe small cell 4(1 is reduced. Specifically,
the link direction setting unit 145 causes the eNodeB 41 to set the TDD configuration
of the sniall cell 40 to be equal or similar to Ihe TDD configuration of the cell 10.
[0ORO]
25 hor example, the link direction setting unit 145, when the small cell 40 is
located in the peripheral portion of the cell 10, causes the eNodeB 41 to set the link
direction of the second fi-equency band in the small cell 40 so that the difference in
link direction between the cell 10 and the small cell 40 is reduced. Specifically, the
link direction setting unil 345 causes the eNodeB 41a U> set Ihe TDD configuration
30 of the CC 2 in the small ceil 40a to be equal or similar to the TDD configuration of
the CC 2 of the cell 10. In this case, for example, similar to the TDD configuration
SF345373WO00
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of the CC 2 of the cell 10, the TDD configuration of the C£] 2 m the small cell 40a is
statically or quasi-statically set,
[0081j
Also, for example, Ihe link direction selling unit 145, when the small cell 40
5 is not located in the peripheral portion of the celt 10, causes the eNodeB 41 to set the
the link direction of the first frequency band in the small coll 40 so that the difference
in Jink direction between Ihe eell 10 and the small cell 40 Is reduced. Specifically,
the link direction setting unit 145 causes the eNodeB 41b to set the TDD
configuration of the CC 1 in the small cell 40h to he equal or similar to the TDD
10 configuration of the CC I of the cell 10. In this case, for example, similar to the
TDD configuration of the CC 1 of the cell 10, the TDD configuration of the CC 1 in
the small cell 40b is dynamically set
[0082]
As a specific technique of controlling the eNodeB 41, the link direction
15 setting unit 145 notifies the cNodcli 41 of the link direction Ibr each sub-frame of the
first frequency band or the link direction for each .sub-frame of the second frequency
band, which has been set by the link direction setting unit 145. As tt result, the link
direclion setting unit 145 causes the eNodeB 41 to set the Hnk direction for each subframe
in the small cell 40. The link direction setting unit 145 performs the
30 nolilicalion of thccNodcB 41, for example, through the network communication unit
120.
[0083]
Note that, as described above with reference to HG 12, the eNodeB 41,
when the small cell 40 is located in the peripheral portion of Ihe eell 103 may
25 dynamically set the link direction for each sub-frame of a frequency band which is
different from the second frequency band, and may not allocate communication
resources of the different frequency band to a UK 200 which is not located in the
peripheral portion of the small cell 40. Specifically, the eNodeB 41 may
dynamically set the TDD configuration of a CC which is different from the CC 2,
30 and may not allocate communication resources of the different CC Eo a UK 200c
which is located in the peripheral portion of the small cell 40a.
SP3d5iJ73WOU0
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[0084]
Similarly, as described above with reference to 1'IG. 12, the cNodeB 41,
when the small cell 40 is not located in the peripheral portion of the cell 105 may
dynamically set the link direction for each sub-frams of a frequency band which is
B different iram the first frequency band, and may not allocate communication
resources of the different frequency band to a terminal device which is located in the
peripheral portion of the small cell 40, Specifically, the cNodeB 41 may
dynamically set the TDD configuration of a CC which is different from the CC 1,
and may not allocate communication resources of the different CC to a Uli 200g
10 which is located in the peripheral portion of the small cell 40b.
[0085]
(Power Control Unit 149)
The power control unit 149 may reduce transmission power in the cell 10
for a sub-name in which the link direction in the cell 10 is different from the link
15 direction in the small cell 40. For example, the power control unit 149 reduces
transmission power of the CC 2 in the cell 10 for a sub-frame in which the link
direction of the CC 2 in the cell 10 is different from the link direction of the CC 2 in
the small cell 40a. Also, for example, the power control unit 149 reduces
transmission power of the CC 1 in the cell 10 for a sub-frame in which the link
20 direction of the CC 1 in the cell 10 is different from the link direction of the CC ] in
the small cell 40b. In this case, for example, the power control unit 149 is notified
of the link direction (i.e., the TDD configuration) in the small cell 40, by IheeNodeB
41 through the network communication unit 120.
[0086]
26 By thus reducing transmission power, interference of a downlink signal of
the cell 10 with an uplink signal of the small cell 40, and interference uf an uplink
signal of the cell 10 with a downlink signal of the small cell 40, can be reduced.
[0087]
(Others)
30 Note that if the number of sub-frames which can be used in communication
in the small cell 40 is limited, sub-frames to be used in communication may be
SP345373WO00
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selected based on (he downJink ox uplink traffic rule in the small coll 40.
Specifically, the ratio of uplink sub-frames and downlink sub-frames in a radio frame
may be changed, depending on the downlink or uplink traffic vale. This will now be
specifically described with reference to FfG. 13.
5 [00881
FIG 13 is a diagram for describing example selection of sub-frames used in
communication in a. small cell, Referring lo FIG 13, a CC 1 which is used as
communication resources for a Uli 200 which is located in the central portion of a
cell 10 is set to have a TDD configuration corresponding to the configuration l of
LO FIG. 3. Also, a CC 2 which is used as communication resources for a UF 200
which is located in the peripheral portion of the cell 10 is set to have a TDD
configuration corresponding lo the con figuration 3 of l'IG 3.
[0089]
In a small cell 40a which is located in the peripheral portion of the cell 10,
15 the downlink traffic rate is higher than the uplink traffic Kite, and therefore, a larger
number of downlink sub-frames are selected as sub-frames to be used in
communication. On the other hand, in a small cell 40c which is located in the
peripheral portion of the cell 10, the uplink traffic rale is higher than the downlink
traffic rate, and therefore, a larger number of uplink sub-frames are selected as sub-
20 frames to be used in communication.
100901
Similarly, in a small cell 40b which is located in the central portion of the
cell 10, the downlink traffic rate is higher than the uplink traffic rate, and therefore, a
larger number of downlink sub-frames arc selected as sub-frames to be used in
25 communication. On the other hand, in a small cell 40d which is located in the
central portion of the cell 10, the uplink traffic rate is higher than the downlink traffic
rate, and therefore, a larger number of uplink sub-frames arc selected as sub-frames
to be used in communication.
[0091J
80 (3)F!owofProccss
Next, an example communication control process according to a variation of
SPiM5373WO00
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Ihe first embodiment will be described with reference Eo FIG. \4. FIG, 14 is a
flowchart showing an example schematic How of the communication control process
ol' Ihe variation of the first embodiment. The communication control process is a
process in an eNodeR 100-1. Here, only step S521 will be described which is the
5 difference between the example communication control process of the first
embodiment described with reference to FIG 10 and the example communication
control process of ihe variation.
[0092]
Instep S521, the link direction setting unit 145 notifies an cNodeB 41 of the
10 link direction for each sub-frame of the CC 1 or the link direction for each sub-frame
of the CC 2, that lias been set by the link direction selling unit 145. As a result, the
link direction setting unit 145 causes the cNodeB 41 to set the link direction for each
sub-frame in the small ce]l 40, The link direction selling unit 145 performs the
notification of the eNodeB 41, Tor example, through the network communication unit
15 120.
|(X)93j
« 3 , Second BmbodJmcnt»
<3. 1. Overview>
The first embodiment has been particularly described with reference to an
20 operation of an cNodeB in a cell adjacent to another cell. Moreover, a variation of
the first embodiment has been particularly described with reference to an operation
of an eNodcB in a macrocell in a case where the cell adjacent Co anolher cell is the
macrocell. Next, a second embodiment cT Ihe present disclosure will be particularly
deseribed with reference to an operation of an eNodcB in a small cell which covers
25 all or part of a maeroeelh In the second embodiment, in the small cell, the link
direction is dynamically set for each sub-frame of a fust frequency band, and the link
direction is set for each sub -frame of a second frequency band so that the difference
in link direction between the small cctl and the macrocell is reduced, i.e., as large a
number of sub -frames as possible have the same link direction. And,
f!0 communication resources of the first frequency band are noE allocated to a terminal
device which is located in (he peripheral portion of the small cell, Tht^ second
SP:M5,™WOOO
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embodiment will now be more specifically outlined with reference to FIGS. 15 and
16.
[0094]
FIGS, 15 and 16 are diagrams for outlining the second embodiment,
£> Referring to FIG 15, a maeroeell 30 and a cell 10 which is a small cell arc shewn.
An eNodeB 100-2 according to this embodiment is an eNodeB in the small cell,
Referring to FIG. 16, the tell 10 which is a small cell is shown in greater detail in
this embodiment, the cell 10 is divided into a peripheral portion which Is further from
the cNodcB 100-2 and a central portion (i.e., a central portion closer to the eNodeB
10 100-2) other than the peripheral portion. And, in the central portion of the cell 10,
the TDD configuration is dynamically set. On the other hand, in the peripheral
portion of the cell 10, the TDD eon figuration is sel to he equal or similar to that of
ihe maerocetl. Also, for example, in the peripheral portion of Ihe cell 10, the TDD
configuration is statically or quasi-statically set.
15 [0095]
For example, in the cell 10 which is a small cell, the cjinier aggregation
technique of aggregating a plurality of cells is used. When the plurality of CCs
include a CC 1 and a CC 2, the CC 1 is nscd as communication resources for a UF
200 which is localed in Ihe central portion of the eell 10, and the CC 2 is used as
20 communication resources for a UF 200 which is located In the peripheral portion
(and the central portion) of the cell 10. For Ihe CC I, the TDD conliguration is
dynamically set hascd on the traffic. For the CC 2, the TDD configuration is set
(e.g., statically or quasi-statically) to be equal or similar to thai of Ihe macrocelh
[0096]
25 By thus setting the TDD configuration and allocating communication
resources, in the cell 10 communication resources of a frequency band in which the
link: direction is dynamically set are allocated only to a UH 200 which is located in
the central portion of the cell 10 which is a small cell. Therefore, in the cell 10,
transmission power of the communication resources can be reduced. As a resuU, an
30 uplink signal on the communication resources of the cell 10 does not substantially
interfere with a downlink signal of the macrocell 30, and a downlink signal on the
SP34 5,173 WODO
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communication resources of the cell !(} docs not substantially interfere with an
uplink signal of the maeroeell 30. Specifically, in a frequency band in which the
link direction is dynamically set, interference of a small cell with a maeroeell, such
as those shown in FIGS. 5 and 6, docs not substantially occur.
G [0097]
Moreover, the distance between a Uli 200 which is located in the central
portion of the cell 10 which is a small cell, and the eNodeB 3 00-2, is smaller than the
distance between an eNodeB 3 I and the eNodeB 100-2, and therefore, a downlink
signal of the maeroeell 30 does not substantially interfere with an uplink signal of the
10 cell 10. Also, Ihe distance between a UB 200 which is located in the central portion
of the cell 10 which is a small cell, and the eNodeB 100-2, is smaller than the
distance between thai UK 200 and a UE 200 which communicates with the cNodcB
31, and Ihereforc, an uplink signal of the macrocc! I 30 docs not substantially interfere
with a downlink signal of the cell 10. Specifically, in a frequency band in which the
15 link direction is dynamically set, interference of a maeroeell with a small cell, such
as those shown in FIGS. 5 and 6, docs not substantially occur,
[0098]
Nolo that, in the cell 10 which is a small cell, only communication resources
of a frequency band (the CC 2) in which the dillerenee in link direction from the
20 maeroeell 30 is small arc allocated to a UF 2(H) which is located in the peripheral
portion of the cell 10, Therefore, in the frequency band, interference, such as those
of FIGS, 5 and 6, docs not substantially occur.
|00991
Therefore, in a radio communication system employing TDD, by
25 dynamically setting the link direction, interference between a maeroee]! and a smalt
cell can be reduced while improving LhroughpuL
J0100J
<3. 2, Configuration of cNodeR>
An example configuration of the cNodeB 100-2 of the second embodimenj
30 will be described with reference to FIG ! 7. FIG 17 is a block diagram showing the
example configuration of the eNodeB 100-2 of the second embodiment. Referring
SP345373WO00
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to 1TG. 17, the eNodeB 100-2 includes a radio eomrminication unit 110, a network
communication unit 120, a storage unit 130, and a processing unit 150.
[01011
Here, the radio communication unit ! 10, (he network communication unit
5 120, and the storage unit 130 arc not different between the first embodiment and the
second embodiment. Also, in the processing unit ISO, the terminal location
measurement unit 341, the traffic rate measurement unit 143, and the resource
control unit 147 are not different between the first embodiment and the second
embodiment, Therefore, here, a link direction setting nnit 155 and a power control
10 unit 159 will be described.
[0102]
(Link Direction Setting Unit 155)
The link direction setting unit 155 dynamically sets the link direction for
each sub-frame o^ the first frequency band, and sets the link direction for each sub-
IB frame of the second frequency band so that the difference in link direction between
the cell 10 and a cell related to the cell 10 is reduced. In this embodiment, the cell
10 is a small cell, and the related cell is a macrocdi 30 which covers all or part of the
cell 10. For example, the link direction setting unit j 55 dynamically sets the TDD
configuration of the CC 1 based on the uplink or downlink traffic rate. As an
20 example, the TDD configuration of the CC 1 is sel every 10 ms to several tens of
milliseconds. Also, the link direction setting unit 155 sets the TDD configuration of
the CC 2 to be equal or similar to the TDD configuration of the CC 2 of the
macroeell 30. As an example, the link direction setting unit 155 is notified of the
TDD configuration of the CC 2 of the macroeell 30 by 31
Note that, in the macrocclt 30, communication resources of a frequency
band corrcsponding to the location of a UE 200 may be allocated to the UF. 200. In
this case, if the cell 10 is located in (he peripheral portion of the macroccl! 30, the
30 second frequency band (e,g,, the CC 2) may be a frequency band which is allocated
to a UF. 200 which is located in the peripheral portion of the rnacrocell 30. Also, if
Sl'345373WO00
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the cell 10 is not located in the peripheral portion of the macroccll 30 (i.e., the cell ](]
is located in the central portion), the second frequency band may be a frequency band
which is allocated to a UE 200 which is not located in the peripheral portion of the
macroccll 30 (i.e., a UE 200 which is located in the central portion),
B [0104]
(Power Control Unit 359)
The power control unit 159 controls transmission power in the cell 30. For
example, the power control unit 159 controls transmission power of the radio
communication unit 110. For example, the power control unit 159 allocates small
10 transmission power to downlink in the firs! irequency hand (e.g., the CC l}; and
large transmission power to downlink: in the second frequency band (e.g., theCC 2).
[0305]
Also, for example, the eNodeB IQ0-2 causes a UE 200 which is located in
the central portion of the cell 10 and in wJiich communication resources of the first
15 frequency band (e.g.; Ihc CC ]) are allocated to uplink to allocate small transmission
power to uplink in the first frequency band. Also, the eNodeB 100-1 causes a UE
200 which is localed in the peripheral portion ol' the cell 10 and in which
communication resources of the second frequency band (e.g., the CC 2) are allocated
to uplink to allocate large transmission power to uplink in the second frequency band.
20 [0106]
Note thai the power control unit 159 may request the eNodell 31 of the
macroeell 30 to reduce transmission power in the macroccll 30 in a sub-frame in
which the link direction of the second frequency band in the cell 10 is different from
the link direction of the second frequency hand in the macroccll 30. For example,
25 the power control unit 159 notifies the eNodeB 31, through the network
communication unit 120, of a sub-frame in which the link direction of the CC 2 in
the cell 10 is different from the link direction of the CC 2 in the macroeell 30. By
thus reducing transmission power in the macroccll 30, interference of a downlink
signal in the macroccll 30 with an uplink signal in the cell 30, and interference of an
30 uplink signal of the macroccli 30 with a downlink signal of the cell 10, can be further
reduced.
sps^rmwooo
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JO J 07]
<3. 3. Flow of PiLocess>
Next, an example eommunication control process according to the second
embodiment will be described with reference to IK1 IS. FIG. IS is a flowchart
5 showing an example schematic flow of the communication control process of the
second embodiment. The communication control process is a process in the
eNodeB 100-2. Steps S5G1-S505 and S511-S517 of the communication control
process of the first embodiment described with reference to 1*1G 10 correspond to
steps SG01-S605 and S611-S6I7 of the communication control process of the
10 second embodiment. Therefore, here, only step S607 will be described which is the
difference between the example communication control process of the first
embodiment described with reference to FIG 10 and the example communication
control process of (he second embodiment.
[0108]
tf» In step S607, the link direction selling unit 155 determines whether or not
the link direction setting unit 155 itself has been notified of the link direction (i.e.,
the TDD configuration) of the CC 2 of the macrocell 30 by the cNodcli 31 through
the network communication unh 120. If the link direction setting unit 155 has been
notified of the link direction, control proceeds to step S61 L Otherwise, control
20 proceeds to step 3613,
[0109]
« 4 . Third F.mbodimenl»
<4. 1. Ovcrvicw>
Next, a third embodiment of the present disclosure will be described- Tn
25 the third embodiment, communication resources in a sub-frame in which the link
direction in a cell is different Jixam the link direction in a cell adjacent to that cell are
not allocated to a terminal device which is located in the peripheral portion of that
cctl. The third embodiment will now he more specifically described with reference
to FIG 19.
30 JOIIO]
FIG 1" is a diagram for outlining the third embodiment. Referring to ITG
SF3-i5373WOCK>
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19, a cell 10a and a cell 10b adjacent to the celt 10a are shown. In the cell 10a and
the cell 10b, the link direction (i.e., Ihe TDD configuration) is dynamically set for
each sub-frame, As an example, in some radio frame, in the cell 10a, a TDD
configuration corresponding Lo the configuration 0 of FIG, 3 is sei for each frequency
5 bund. Also; in the same radio frame, in the cell 10b, a TDD configuration
corresponding lo the configuration 6 of FIG 3 is set lor each frequency band. In
this case, a sub-frame in which the link direction of the cell 10a is different from the
link direction of the cell 10b is the sub-frame #9. Therefore, while interference
such as thai shown in Fit! 4 does not occur in the sub-frames #0-ftS, interference
10 such as that shown in FIG. 4 occurs in the sub-frame #9, Therefore, hi this
embodiment, while communication resources in Ihe sub-frames #0-8 may be
allocated to any Uli 200, communication resources in The sub-frame #9 arc not
allocated to a UE 200 which is located in the peripheral portion of Ihe celt 10,
Speciikally, communication resources in the Huh-frame #9 arc allocated only to a UE
15 200 which is located in the central portion of the cell 10,
[0111]
Ey thus allocating communication resources, communication resources are
allocated only to a UE 200 which is located in the central portion of the eel! 10, in a
sub-frame of a radio frame in which the link direction is different between adjacent
20 celts. Therefore, transmission power in the sub-frame can be reduced. As a result,
in the sub-frame, an uplink signal of the cell 10 docs not substantially interfere with a
downlink signal of an adjacent cell, and a downlink signal of Ihe cell 10 does noE
substantially interfere with an uplink signal of an adjacent cell. Specifically, even
in a sub-frame in which the link direction is different between adjacent cells,
25 interference such as that shown in FIG 4 does not substantially occur. Also, of
course, even in a sub-frame of a radio frame in which the link direction is the same
between adjaccnl cells, interference such as that shown in ITG. 4 docs not
substantially occur. Therefore, in a radio communication system employing TDD,
by dynamically setting the link direction, interference between adjacent cells can be
80 reduced while improving throughput.
[0U2]
SP345373WO00
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An example configuration of an cNodcli 100-3 according to the third
embodiment will be described with reference to FIG. 20, FIG 20 is a block diagram
showing the example configuration of llie eNodeB 100-3 of the third embodiment.
5 Referring to I*1G. 20, the eNodeB 100-3 includes a radio communication unit 110, a
network communication unil 120, a storage unit 130, and a processing unit 160.
[0113]
Hero, the radio communication unit 110, the network communication umt
120, and the storage unit J 30 are not different between the first embodiment and the
10 third embodiment. Also, in the processing unit 160, Ihe terminal location
measurement unit 141 and the traAic rafe measurernenl unit 143 arc not different
between the first embodiment and the third embodiment Therefore, here, a link
direction setting unit 165, a resource control unit 167, and a power control unit !69
will be described.
15 |QI14|
(Link Direction Setting Unil 165)
Hie Jink direction setting unit 165 dynamically sets the link direction for
each sub-frame of one or more frequency bands. For example, the one or more
frequency bands include a CC I and a CC 2. The Jink direction setting unit 165
20 dynamically sets any of the TDD configurations of FIG 3 for the CC ! and the t'C 2
based on the uplink oi downlink traffic rate. As an example, the TDD configuration
is set cvciy 10 ms to several tens of milliseconds. For the CC] I and the CC 2, the
same TDD configuration may be scl, or different TDD configurations may be set.
10115]
25 Also, the link direction setting unit 165 notifies an adjacent cell of the link
direction (i.e., the TDD configuration) in the cell 10, lor example, through the
network communication unit 120.
|0116|
(Resource Con Iro I Unit 167)
SO The resource control unit 167 controls allocation of communication
resources to a UE 200 based on the setting of the link direction of a channel in which
RP34r>,™woo<)
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the link direction can be dynamically set for each snb-fraine, and the location of the
UR 200 in the cell 10, In particular, in tills embodiment, Ihe resource control unit
167 does not allocate communication resources in a sub-frame in which the link
direction in the cell 10 is different from the link direction in a cell related to the cell
5 If), to a UE 200 which is located in the peripheral portion of me cell 10. The
related cell is a cell adjacent to the cell 10. Tor example, when the sub-frame in
which the link direction is different between the ce!3 10 and the adjacent cell is the
sub-frame #9, the resource control unit 167 docs not allocate communication
resources in the sub-frame #9 to a UE 200 which is located in the peripheral portion
10 of the ceil 10. Specifically, the resource control unit 167 allocates communication
resources in the sub-frame #9 only to a UE 200 which is located in the central
portion of the cell 10, Also, the resource control unit 167 allocates communication
resources in the sub-frames W0 X to a UK 200 which is located in the peripheral
portion of the cell 10 and a UE 200 which is located in the central portion of the cell
15 10.
[0117]
Note that the resource control unit 167 is notified of the link direction (i.e.,
the TDD configuration) in the adjacent cell bythceNodeB 100-3 in the adjacent cell.
[011S[
20 (Power Control Unit 169)
The power control unit 169 controls transmission power in thcecll 10. For
example, the power control unit 169 reduces transmission power in the cell 10, in a
sub-frame in which the link direction in the cell 10 is different from the link direction
in a cell adjacent to the cell 10. More specifically, the power control unit 169
25 allocates small transmission power to downlink. Also, the power control unil 169
causes a UE 200 which is located in the central portion of the ceil 10 to allocate
small transmission power to uplink.
[0119]
<4. 4. How of Proccss>
30 Next, an example communication control process according to the third
embodiment will be described with reference to FIG 21. VIG. 21 is a flowchart
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showing an example schematic How of the communication control process of the
third embodiment. Note that the communication control process is a process in the
cNodcB 100-3,
[0120]
5 initially, Jii step S7G1, the terminal location measurement unit 141 measures
the location or a Uli 200 in the cell 10. AJso, in step S703, the traffic rate
measurement unit 143 measures the uplink traffic rate and the downlink traffic rate in
the coll 10.
[0121]
10 In step S705, the link direction setting unit 165 sets the link direction (i.e.,
the TDD configuration) for each sub-frame based on the measured traffic rates,
Atso; in step S707, the link direction selling unit 165 notifies an adjacent cell of the
link direction in the cell 10: for example, through the network communication unit
120. Also, in step S7G9, the resource control unit 167 is notified of the link
15 direction (i.e., the TDD configuration) in the adjacent cell by the adjacent cell
[0122]
in step S711, the resource control unit 167 allocates communication
resources in a sub-frame in wliich the link direction in the cell 10 is different from
the link direction in a cell adjacent to the cell 10, to at JF 200 which is not located in
20 the peripheral portion olthc coll 10 (i.e., a UK 200 wliich is located in the central
portion of the cell 10), Also, in step S713, the resource control unit W7 allocates
communication resources in a sub-frame in which the link direction in the ceil 10 is
the same as the link direction in a cell adjacent to the cell 10, to a UR 200 which is
located in the cell 10,
25 [0123]
In step S715, the radio communication unit ] 10 communicates with the UE
200 using the allocated communication resources.
[0124]
«5. I'ourth limbodiment»
30 <5. )- Overvicw>
The third embodiment has been particularly desei-ihed with reference to an
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operation of an eNodeB in a cell adjacent to another cell. Next, a fourtti
embodiment of the present disclosure will he particularly described with reference to
an operation of an eNodeB in a small cell which covers all or part of a macroccU.
In the fourth embodiment, communication resources in a sub-frame hi which the link
5 direction in a small cell is different from the link direction in a macrocel! which
covers all or part of the small cell, are not allocated to a terminal device which is
located hi the peripheral portion of the small cell, in the small cell. The fourth
embodiment will now be more specifically outlined with reference to FIG. 22.
[0125]
10 FIG 22 is a diagram for outlining the fourth embodiment. Referring to FIG
22, a cell 10 which is a small cell, and a macrocel! 30 which covers all or part of the
ceJl 10, are shown. In the cell I0; the lint: direction (i.e., the TDD configuration) is
dynamically set for each sub-frame. On the other hand, in the macrocell 30, the
link direction (i.e., the TDD configuration) may be dynamically, or alternatively
15 statically or quasi-statically, set for each sub-frame. As an example, in some radio
frame, in the cell 10, in each frequency band, a TDD configuration corresponding to
the configuration A of FIG 3 is set. Also, in the same radio frame, in the macrocell
303 in each frequency band, a TDD configuration corresponding to the con figuration
0 of FTG. 3 is set. In this case, a sub-frame in which the link direction in the cell 10
20 is different from the link direction in the macrocell 30 is the sub-frame #9.
Therefore, while interference such as those shown in FIGS, 5 and 6 docs not occur in
the sub-frames tf0-#8, interference such as those shown in FIGS. 5 and 6 may occur
in the sub-frame #9. Therefore, in this embodiment, in the cell 10, while
communication resources in the sub-frames #0-8 arc allocated to any UE 200,
25 communication resources in the sub-lrame #9 are not allocated to a UE 200 which is
located in the peripheral portion of the cell 10. Specifically, in the cell 10,
communication resources in the sub-frame #9 are allocated only to a UK 200 which
is located in the central portion of the cell 10.
[0126]
30 By thus allocating communication resources, communication resources are
allocated only tit a UK 200 which is located in the central portion of the cell 10, in
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(he cell 10, in a sub-frame of a radio frame in which the link direction is different
between the cell 10 which is a small cell and the macroccli 30. Therefore, in the
cell 10, transmission power in the sub-frame can be reduced. As a result, in the
sub-frame, an uplink signal of the cell 10 does not substantially interfere with a
5 downhnk signal of the macroccli 30, and a downlink signal of the cell 10 does not
substantially interfere wilh an uplink signal of the macroccli 3(1. Specifically, even
in a sub-frame in which the link direction is different between adjacent cells,
interference of a small cell with a macroceli, such as those shown in FIGS. 5 and 6,
does not substantially occur.
10 [0127]
Moreover, the distance between a LIE 200 which is located in the central
portion of the cell 10 which is a small cell and an cNodeB 100-4 is smaller than the
distance between an eNodeB 31 and the eNodeB 100-4, and therefore, a downlink
signal of the macroceli 30 does not substantially interfere with an uplink signal of the
15 cell 10. Also, the distance between a UE 200 which is located in the central portion
of the cell 10 and the eNodeB 100-4 is smaller than the distance between that UE
200 and a UK 200 which communicates with the eNodeB 31, and therefore, an
uplink signal of the macroceli 30 does not substantially interfere with a downlink
signal of the cell 10. Specifically, even in a sub-frame in which the lint direction is
20 different between adjacent cells, interference of a macroceli with a small cell, such as
those shown in FKJS. 5 and 6, docs not substantially occur.
[0I2SJ
Also, of course, even in a sub-frame of a radio frame in which the link
direction is the same between the cell 10 and the maeroeell 30, interference such as
'lb those shown in FIGS. 5 and A docs not occur.
[0L29J
There I ore, in a radio communication system employing TDD, by
dynamically setting the link direction, interference between adjacent cells can be
reduced while improving throughput.
,10 |0I30[
<5. 2. Configuration of cNodcli>
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An example configuration of the cNodcli 100-4 of the fourth embodiment
will he described with reference to FIG 23. FIG 23 is a block diagram showing an
example configuration of (he eNodeR 3 00-4 of Ihe fourth embodiment. Referring
lo FIG 23, the cNodcB 100-4 includes a radio communication unit 110, a network
5 communication unit 320, a storage unit 130, and a processing unit 170,
[0131]
Here, the radio communication unit 110, the network communication unit
120, and the storage unit 130 are not different between the third embodiment and the
fourth embodiment. Also, even in the processing unit 170, the terminal location
10 measurement unit 141, the traffic rate measurement unit I43: and the link direction
selling unit 165 arc not different between the third embodiment and the fourth
embodiment. Therefore, here, a resource control unit 177 and a power control unit
179 will be described.
[0I32J
15 (Resource Control Unit 177)
The resource control unit 177 controls allocation of communication
resources to a UE 200 based on the setting of the link direction of a channel in which
the link direction can be dynamically set for each sub-fraine, and the location of the
Uli 200 in the cell 10. In particular, in this embodiment, the resource control unit
20 177 does not allocate communication resources in a sub-frame in winch the link
direction in the cell 10 is different from the link direction in a cell related hi the cell
10, to a UF 200 which is located in the peripheral portion of the cell 10. Hero, the
cell tO is a small cell, and the related cell is a macrocell which covers all or part of
the cell 10, For example, when the sub-frame in which the link direction is
25 different between the cell 10 and the maeroccil 30 is the sub-frame #9, the resource
control unit 177 does not allocate communication resources in the sub-frame H9 to a
Uli 200 which is located in the peripheral portion of the cell 10. Specifically, the
resource control unit 177 allocates communication resources in the sub-frame #9
only to a Uli 200 which is located in the central portion of the cell 10. Also, the
30 resource control unit 167 allocates communication resources in the sub-frames #0-8
to a UE 200 which is located in the peripheral portion of the cell 3 0 and a UF 200
SV34S373WO00
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which is located in the vulval portion of the cell 10,
[0133]
Note that the resource control unit 177 is notified of the link direction (i.e.,
theTDDcordiguralion)in thcmacroccli 30 by the eNodeB 31 of the macrocell 30.
5 [0134J
(Power Control Unit 179)
The power control unit 179 controls transmission power in Hie cell 3 0. For
example, the power control unit 179 reduces transmission power in the cell 10, in a
sub frame in which the link direction in the cell 10 is different from the link direction
10 in (Tie macroccil 30. More specifically, the power control unit 179 allocates smah
transmission power lo downlink. Also, the power control unit 179 causes a UO 200
which in located in the central portion of the cell 10 to allocate small Iransmission
power to uplink.
[0135]
IT* Note that the power control unit 179 may request the eNodeB 31 of the
macrocell 30 lo reduce transmission power in the macroccil 30 in a sub-frame hi
which the link direction in the cell 10 is different from the link direction in the
macrocell 30, For example, the power control unit I 79 notifies the eNodeB 31,
through the network communication unit 120, of a sub-frame in which the link
20 direction in the cell 10 is dillerenl from the link direction in the macroccil 30. By
thus reducing transmission power in the macroccil 30, interference of a downlink
signal of the macrocell 30 with an uplink signal of the cell 10, and interference of an
uplink signal of the macroccil 30 with a downlink signal of the cell 10, can be further
reduced.
25 [0136]
<5. 3. Flow of Process >
Next, an example communication control process accoi\ling to (he fourth
embodiment will be described with reference lo FTG 24. HG. 24 is a flowchart
showing an example schematic tlow of the communication control process of the
30 fourth embodiment. Note that Ihe communication control process is a process in
the eNodeB 100-4. Steps S701--S705 and S715 of the communication control
SP345373WO00
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process of the third embodiment described with reference to FIG 21 correspond to
steps S801 SK05 and SSI5 of the communication control process ol" Ihe fourth
embodiment, respectively. Therefore, here, only stops S807, S811, and S813 will
be described which is the difference between the example communication control
5 process of the third embodiment described wifh reference lo FIG. 2\ and the example
communication control process of the fourth embodiment.
[0137J
In step S807, the resource control unit 177 is notified of the link direction
(i,e.s the TDD configuration) in the macrocell 30 by the eNodeB 31 of the macroccJI
10 30.
[0138]
In step S811, the resource control unit 177 allocates cojnmunication
resources in a sub frame in which the link direction in the cell 10 is different from
the link direction in the macrocell 30 to a UE 200 which is not located in the
ltt peripheral portion of the cell 10 (he.: a UK 200 which is located in the central portion
of the cell 10). Also, in step SS13, the resource control unit 177 allocates
communication resources in a sub-frame in which the link direction in the cell 10 is
the same us the link direction in the macrocell 30 to a UE 200 which is located in the
celt 30.
20 fOB9]
« 6 . Sufiimary»
The eNodeB 100 of the embodiments of the present disclosure have been
described above with reference to FIGS, 1-24. According to these embodiments,
allocation of communication resources lo a UK 200 is controlled based on the setting
25 ol' Ihe link direction of a channel in which the link direction can be dynamically set
for each sub-frame, and the location ol' the UK 200 in the cell 10.
L0140 j
For example, as in the first embodiment and the second embodiment, the
link direction is dynatnicalry set for each sub-frame of the livsf frequency band, and
30 the link direction is set for each sub-frame of the second frequency band so that the
difference in link direction between the cell 10 and a cell (an adjacent ceil or a
sr'345:mw<>0Q
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macrocell) related to the cell 10 is reduced. And, communication resources of the
first frequency band are not allocated to a Uli 200 which is located in the peripheral
portion of the cell f0,
[0141]
fi By thus setting the TDD configuration and allocating communication
resources, communication resources of a frequency band in which the link direction
is dynamically set are allocated only to a UE 200 which is allocated in Ihe central
portion of the cell 3 0, Therefore, Iransmission power of the communication
resources can be reduced. As a result, an uplink signal on Ihe communication
JO resources does not substantially interfere with a downlink signal of a related cell, and
a downlink signal on the communication resources docs not substantially interfere
with an uplink signal of a related cell. Specifically, in a frequency hand in which
the link direction is dynamically set, interference such as those shown in 1/1US. 4-6
does not substantially occur. Note that only communication resources of a
15 frequency band in which Ihe diflerence in link direction from a related cell is small
are allocated to a ULJ 200 which is located in the peripheral portion of ihe cell 10,
Of course, in the frequency band, interference such as those shown in PIGS. 4-6
does not substantially occur. Therefore, in a radio communication system
employing TDD, by dynamically setting the link direction, inlerference between
20 adjacent cells can be reduced while improving throughput.
|0142|
Also, for example, as in the third embodiment and the fourth embodiment,
communication resources in a sub-frame in which the link direction in the cell 10 is
different from the link direction in a cell (an adjacent cell or a macrocell) related to
25 Ihe cell 10 arc not allocated to a Uli 200 which is located in Ihe peripheral portion of
the cell 10.
I0!43j
By thus allocating communication resources, communication resources arc
allocated only to a Uli 200 which is allocated in the central portion of the cell 10, in a
30 sub-frame of a radio frame in which the link direction JS different between the cell 10
and a related cell. Therefore, in the cell 10, transmission power in ihe sub-frame
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can be reduced. As a result, in the sub-frame, an uplink signal of the cell 10 does
not substantially interfere with a downlink signal of a related ceil, and a downlink
signal of Ihc ceil 10 docs not substantially interfere with an uplink signal of a related
cell. Specifically, even in a sub-frame in which ihc link direction is different
5 between the cell 10 and a related cell, interference such as those shown in FIGS, 4-6
does not substantially occur. Also, of course, even in a sub-frame of a radio frame
in which the link direction is the same between adjacent cells, interference such as
those shown in FIGS. 4-6 docs not substantially occur. Therefore, in a radio
communication system employing TDD, by dynamically setting the link direction,
10 interference between adjacent cells can be reduced while improving throughput,
[0144]
The preferred embodiments of the present invention have been described
above with reference to the accompanying drawings, whilst the present invention is
not limited to the above examples, of course. A person skilled in the ait may find
15 various alterations and modifications within the scope of the appended elaims7 and it
should be understood that they will naturally come under the technical scope of the
present invention.
[OI45J
Although, for example, in the above embodiments, die assumed radio
20 communication system is compliant with LTE or LTE-Advanced, tbe present
technology is not limited to this example. For example, the assumed radio
communication system may be a radio communication system which is similar to
LTE or LTli-Advanced, or may be a radio communication system which is compliant
with a standard which is further developed from LTE or LTE-Advanced,
2fi |0I461
Also, although, in the above embodiments, a communication control device
which pciforms a communication control on a cell is an cModcli of LIE or LTEAdvanced,
the present technology is not limited to this example. For example, the
communication control device may be a base station compliant with other
30 communication standards, or may be a device which is a pail of (lie base station.
Also, the communication control device may be another device winch controls a base

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station.
[01471
Also, although, in the above embodiments, a terminal device which
communicates in a cell is a UE of LTE or LTE-Advanced, the present technology is
5 not limited to this example. For example, the terminal device may be a terminal
device compliant with another communication standard.
[0148]
Additionally, the present technology may also be configured as below.
(i)
J.0 A communication control device including:
a radio communication unit which communicates with one or more terminal
devices in a cell over a channel in which a link direction is allowed to be
dynamically set for each sub-frame which is a uuit of time in radio communication;
and
15 a control unit which controls allocation of communication resources to the
terminal device based on the setting of the link direction of the channel and a
location of the terminal device in the cell.
(2)
The communication conlrol device according to (1), wherein
20 the channel includes at least a first frequency band and a second frequency
band,
the communication control device further includes a setting unit which
dynamicahy sets a link direction for each sub-frame of the first frequency band, and
sets a link direction for each sub-frame of the second frequency band so that a
25 difference in link direction between the cell and a cell related to the cell is reduced,
and
the control unh does not allocate communication resources of the first
frequency hand to a terminal device which is located in a peripheral portion of the
cell
30 (3)
The communication control device according to (2), wherein
SP345373WO0O
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the related cell is a cell which is adjacent to the cell,
(4)
The communication control device according to (3), wherein
the cell is amacrocell which covers all or part of a small cell: and
fi the setting unit causes a communication node in the small cell to set a link
direction for each sub-frame in the small cell so Ihat a difference in link direction
between the cell and the small cell is reduced.
(5)
The communication control device according to (4), wherein
10 the setting unit, when the small cell is located in a peripheral portion of the
cell, causes the communication node of tlie small cell to set the link direction of the
second frequency band in the smalt cell so that a difference in link direction between
tlie cell and the smalt cell is reduced.
(6)
15 The communication control device according to (5), wherein
the communicatiou node, when the small cell is located in a peripheral
portion of tlie cell, dynamically sets a link direction for each sub-frame of a
frequency band which is different from the second frequency band, and docs not
allocate communication resources of Ihc different frequency band to a terminal
20 device which is located in a peripheral portion of the small cell,
(?)
The communication control device according to any one of (4) to (6),
wherein
the setting unit, when the small cell is not located in a peripheral portion of
25 the cell, causes tlie comnumicalion node in the small cell to set the link direction of
the fust frequency band in the small cell so that a difference in link direction between
the ccU and the small cell is veduced,
(8)
Itic communication control device according to (7), wherein
30 Ibe communication node, wheu the small ceU is not located in a peripheral
portion of tlie cell, dynamically sets a link direction for each, sub frame of a
spfrjri.™wono
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Ji-equeney band which is different from the first frequency band, and docs not
allocate communication resources of the different irequeney band to a terminal
device which Is located in a peripheral portion of the small cell.
C)
5 The communication control device according to any one of (4) to (8),
wherein
the setting unit notifies the communication node of the link direction for
each sub-frame of the first frequency band or the link direction for each sub-frame Of
the second frequency band which hove been set by the selling unit, and causes the
10 communication node to set the link direclion for each sub-frame in the small cell.
(1(1)
The communication control device according to any one of (4) to (9),
wherein
the control unit reduces transmission power in the cell in a sub-frame in
15 which a link direction in the cell is different from a link direction in the small cell.
{10
The communication control device according to (2), wherein
the cell is a small cell, and
the related cell is a maerocell which covers all or part of thccclh
20 (12)
The communication control device according to (H); wherein
in the related ceil, communication resources of a frequency band
corresponding to a location of a terminal device are allocated to the terminal device,
and
25 the second frequency band is a frequency band which is allocated lo a
terminal device which is located in a peripheral portion of the related cell when the
cell is located in a peripheral portion of the related cell, and a licquency band which
is allocated to a terminal device which is not located in a peripheral portion of the
related ceil when the cell is not located in a peripheral portion ofihe related celL
TO (13)
The communication control device according to (U) or (12), wherein
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the contml unit requests a communication node of the related ceil to reduce
transmission power in the related cell in a sub-frame in which the link direction of
the second frequency hand in the cell is different from the fink direction of the
second frequency hand in the related cell.
6 (14)
The communication control device according to any one of (2) to (13),
wherein
the setting unit statically or quasi-statically sets the link direction for each
sub-frame of the second frequency band.
10 (15)
The comtnunication control device according to any one of (2) to (14),
wherein
the iirsl frequency hand and the second frequency band arc each a
component carrier.
15 (16)
The communication control device according to (1), wherein
the control unit does not allocate communication resources in a sub-frame in
which a link direction in the cell is different from a link direction in a cell related to
Iho cell Eo a terminal device which is located hi a peripheral portion of the cell
20 (17)
I lie cominuiucation control device according to (16), wherein
the related cell is a cef J which is adjacent to the cell.
(18)
The communication control device according to (36), wherein
25 the cell is a small ceil, and
the related cell is amacrocell which covers all or part of the cell.
(19)
A communication control method including:
communicating with one or more terminal devices in a cell over a channel in
30 which a link direction is allowed to be dynamically set for each sub-frame which is a
unit of time in radio communication; and
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controlling allocation of communication resources to the terminal device
based on the setting of the link direction of the channel and a location of the terminal
device in the cell,
(20)
5 A terminal device including:
a radio communication unit which communicates with a hasc station in a
cell over a channel in which a link direction is allowed to be dynamically set ibr each
sub-frame which is a unit of time in radio communication,
wherein the radio communication unit communicates with the base station
IG according to allocation of communication resources to the terminal device itself by
the base station based on the setting of the link direction of the channel and a
location of the terminal device itself hi the cell.
15
20
25
30
Reference Signs List
[0349]
10
11,31,41
13,33,43
23,25,27
21
30
40
100
110
120
no
]40, 150,
141
143
145,155,
147, !67,
160,170
165
177
cell
eNodeB
downlink signal
uplink signal
UF.
macroceil
small cell
cNodcB
radio communication unit
network communication unit
storage unit
processing unit
terminal location measurement unit
traffic rate measurement unit
link direction setting unit
resource control unit
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I49: 159, 169, 179 power control unit
200 user equipment (UF)
210 radio communication unit
220 slovage unit
5 230 processing unit
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CLAIMS
Ctaim 1
A communication control device comprising:
a radio communication unit which communities with one or more terminal
5 devices in a cell over a channel in which a link direction is allowed to be
dynamically set for each sub-frame which is a unit of time in radio communication;
and
a control unit which controls allocation of communication resources to the
terminal device based on the setting of the link direction of the channel and a
10 location of ihe terminal device in the cell.
Claim 2
"l"hc communication control device according to claim 1, wherein
the channel includes at least a first frequency band and a second frequency
15 band,
the communication control device further includes a selling unil which
dynamically sets a link direction Tor each sub-frame of the first frequency band, and
sets a link direction for each sub-frame of the second frequency band so lhat a
difference in link direction between the cell and a cell related to the cell is reduced,
20 and
the control unil does nol altocale communication resources of the first
frequency band to a terminal device which is located in a peripheral portion of the
cell.
25 Claim 3
The communication control device according to claim 2, wherein
the related celt is a cell which is adjacent to wherein
the cell is a small cell, and
the related cell is a macroceJl which covers all or part olihe cell.
20
Claim 12
the communication control device according to claim II, wherein
in the related cell, communication .resources of a frequency band
corresponding to a location of a terminal device are allocated to the terminal device,
25 and
the second frequency band is a frequency band which is allocated to a
terminal device which is located in a peripheral portion of the related cell when Ihc
cell is located in a peripheral portion of the related cell, and a frequency band which
is allocated to a terminal device which is not located in a peripheral portion of the
30 related ceil when Ihe celt is not located in a pes-ipheral portion of the related cell.
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Claim 13
The communication control device according to claim 11, wherein
the control unit requests a communication node of the related cell to reduce
transmission power in the related cell in a sub-frame in which Ihe link direction of
5 tlie second frequency band in the cell is different from the link direction of the
second frequency band in the related cell,
Claim 14
The conrmuni cation control device according to claim 2, wherein
10 the setting unit statically or quasi-staticaily sets the link direction for each
sub-frame of the second frequency band.
Claim 15
The commonication control device according to claim % wherein
15 the first frequency band and the second frequency band ate each a
component carrier,
Claim 16
The communication control device according to claim l, wherein
20 the control unit does not allocate communicalion resources in a sub-frame in
which a Hnk direction in the cell is different from a link direction in a cell related to
the cell to a terminal device which is located in a peripheral portion olthecclL
Claim 17
25 The communication control device according to claim 16, wherein
the related cell is a cell which is adjacent to the cell-
Claim 18
The communication control device according to claim 16, wherein
30 the cell is a small cell, and
the related cell is a macroccll which covers all or part of the cell.
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Claim 19
A communication control method comprising:
communicating with one or move terminal devices in a cell over a channel in
5 which a link direction is allowed to he dynamically set Jbr each sub-frame which is a
unit of time in radio communication; and
. controlling allocation of communication resources to the terminal device
based on the setting of the link direction of the channel and a location oi'the terminal
device in the cell,
10
Claim 20
A terminal device comprising:
a radio communication unit wiiich communicates with a ha.se station in a
cell over a channel in which a link direction is allowed to be dynamically set for each
15 snb-fianic which is a unit of time in radio communication,
\ wherein Ihe radio communication unit communicates whh the base slalion
according to allocation ol" communication resources 1o the terminal device itself by
Lhe base station based on the setting of the link direction of the channel and a
location of the terminal device itself'in Ihe cell