DESCRIPTION
WIRELESS RESOURCE ALLOCATION METHOD AND WIRELESS RESOURCE
ALLOCATION DEVICE, AND COMMUNICATION SYSTEM
5 TECHNICAL FIELD
[0001]
The technology disclosed in the present disclosure
relates to a wireless resource allocation method, a wireless
resourceallocationdevice, andacommunicationsystem, which
10 are capable of deciding an allocation of wireless resources
in a cellular system operating according to a time division
duplex (TDD) scheme, and more particularly, to a wireless
resource allocation method, a wireless resource allocation
device, and a communication system, which are capable of
15 performing an allocation of wireless resources to avoid
interferencecausedasanuplinkandadownlinkaremismatched
whendifferent configurations are usedinneighboring cells.
BACKGROUND ART
20 [00021
Currently, in the thirdgenerationpartnershipproject
(3GPP), an international standard "international mobile
telecommunications (1MT)-2000" of a 3Gmobile communication
system designed by an international telecommunication union
25 (ITU) isbeingstandardized. Longtermevolution (LTE) which
is one of data communication specifications designed by the
3GPP is a long term advanced system aiming for the fourth
generation (4G) IMT-Advanced, and is called "3.9G (super 3G) ."
One of features of 4G lies in that a maximum communication
30 rateoraqualityimprovementatacelledgecanbe implemented
using a technique such as a relay or a carrier aggregation.
[00031
In the long term evolution (LTE), two duplex schemes
of frequency division duplex (FDD) and time division duplex
(TDD) can be selected.
5 [0004]
In the FDD, an uplink-dedicated band and a
downlink-dedicated band are used. In the uplink and the
downlink, a format of a radio frame confiqured with 10
consecutive sub frames is used. Here, an uplink refers to
10 communication from a user equipment (UE) (terminal) to an
eNodeB (base station), andadownlinkrefersto communication
from an eNodeB to a UE.
[0005]
In the TDD, a format of a radio frame configured with
15 ten consecutive sub frames is used. However, in the TDD,
communication is performed using the same band in the uplink
and the downlink. For this reason, as illustrated in Fig.
18, a radio frame configured with ten consecutive sub frames
#Oto #9 is shared andused such that sub frames are allocated
20 as an uplink sub frame and a downlink sub frame (in Fig. 18,
"D" represents a downlink sub frame, "U" represents an uplink
sub frame, and "S" represents a special sub frame (which will
be described later)).
[00061
25 Meanwhile, in the TDD, it is necessary to secure a time
to switch the downlink and the uplink. Specifically, when
an allocation of a sub frame switches from the downlink to
the uplink, it is necessary to insert "a special sub frame".
From a point of view of an eNodeB side, a downlink signal of
30 an eNodeB is subjected to a propagation delay in space and
aprocessingdelayina UE and thus delayedcompared to a downlink
position of a format u n t i l reception of the downlink s i g n a l
is completed by the UE. Meanwhile, i n order f o r an uplink
s i g n a l of an UE t o reach an eNodeB up t o an uplink p o s i t i o n
of a format, an UE needs t o s t a r t transmission of the uplink
5 signal before t h e u p l i n k p o s i t i o n o f t h e format. Therefore,
a special sub frame i n s e r t e d between a downlink sub frame and
an uplink sub frame is defined by an area (a downlink p i l o t
timeslot: DwPTS) b ~daela y of a downlink sig-nal, an area (an
uplink p i l o t timeslot: UpPTS) corresponding t o a degree by
10 which an uplink signal is transmitted early, and a gap (gap
period) betweenthetwoareas. Fig.19illustratesanexample
i n which a special sub frame is inserted a f t e r the sub frame
#lwhenswitching f r o m t h e d o w n l i n k t o t h e u p l i n k i s p e r f o r m e d
between the sub frame #O and the sub frame #2 i n t h e r a d i o
15 frame using the configuration i l l u s t r a t e d in Fig. 18. As
described above, the TDD has the demerit t h a t it is necessary
t o i n s e r t a special sub frame when switching between the
downlink and the uplink is performed (switching from the
downlink t o the uplink is performed).
20 [0007]
For example, a c e l l u l a r communication system i n which
a t l e a s t one of sub frames available for uplink or downlink
t r a f f i c is configured t o include a portion used in uplink
t r a f f i c , aportionusedindownlinktraffic, andaguardperiod
25 portion used as a guard period scheduled between the uplink
portionandthedownlinkportion, andat l e a s t two consecutive
periods of the t h r e e p o r t i o n s can be changed t o comply with
the current necessityof a systemhas beenproposed ( f o r example,
see Patent Document 1).
30 [00081
The TDD of the LTE is defined in the 3GPP Re1 8. Fig.
20 illustrates seven configurations 0 to 6 of the TDD defined
in the LTE (TS36.211 Table 4.2-2). Generally, an operator
is considered to use one of the seven configurations.
Therefore, the operator is not considered to use different
5 configurations in neighboring eNodeBs.
[0009]
When neighboring eNodeBs use different TDD
confiqurations, as can be understood from Fig. 20, links of
different directions such as the uplink and the downlink are
10 allocated at the position of at least one of the sub frames
#3, #4, and #6 to #9, that is, the uplink and the downlink
are mismatched.
[00101
Fig. 23 illustrates an example in which links of
15 different directions such as the uplink and the downlink are
allocatedatthepositionofthe same sub frame of neighboring
eNodeBs. In Fig. 23, in a cell 1, a downlink signal is
transmitted from an eNodeB to a UE, and in a cell 2, an uplink
s i g n a l i s t r a n s m i t t e d f r o m a U E t o aneNodeB. It isunderstood
20 that a transmission signal from the eNodeB at the time of
downlink in the cell 1 serves as interference to a reception
signal of the eNodeB at the time of uplink in the neighboring
cell 2. Further, it can be understood that a transmission
signal from the UE at the time of uplink in the cell 2 serves
25 as interference to a reception signal of the UE at the time
of downlink in the neighboring cell 1. In Fig. 23, a downlink
or uplink transmission signal between the eNodeB and the UE
in the same cell is indicated by a solid line, and a signal
serving as interference tothe neighboring cell is indicated
30 by a dotted line.
[0011]
Fig. 24 i l l u s t r a t e s an example i n which d i f f e r e n t TDD
configurations are used i n r e l a t i v e large areas. For example,
such configuration switching occurs i n the boundary between
Chiba Prefecture and Tokyo Metropolitan. In Fig. 24, the
5 configuration 0 is used i n the l e f t area, and the configuration
1 is used i n the r i g h t area. Referring back t o Fig. 20, when
t h e area using the configuration 0 is adjacent t o t h e a r e a
u s i n q the confiquration 1, the uplink and the downlink a r e
mismatched a t the positions of the sub frames #4 and #9.
10 [0012]
Fig. 24 i l l u s t r a t e s an example i n which the sub frame
#4 is allocated for the uplink (UP) i n the l e f t a r e a using
the configuration 0 but allocated f o r the downlink (DN) i n
t h e r i g h t a r e a u s i n g t h e c o n f i g u r a t i o n l . Whendifferent TDD
15 configurations are used i n r e l a t i v e large areas, a boundary
surface i n which the uplink and the downlink are mismatched
extends across a r e l a t i v e broad area as indicated by a thick
1 i n e i n F i g . 24. Further, thereoccursaprobleminthatalong
the mismatch boundary surface, a transmission signal from an
20 eNodeB a t the time of downlink serves as interference t o a
reception signal of a neighboring eNodeB a t the time of uplink,
and a transmission signal from a UE a t the time of uplink serves
as interference t o a reception signal of a UE a t the time of
downlink i n a neighboring c e l l .
25 [00131
Fig. 25 i l l u s t r a t e s an example i n which c e l l s using
d i f f e r e n t TDD configurations a r e l o c a t e d a spot-likemanner.
In Fig. 25, i n an area using the configuration 1, only a c e l l
indicatedby a t h i c k l i n e is assurnedto use the configuration
30 0. When the area using the configuration 0 is adjacent t o
t h e a r e a u s i n g t h e c o n f i g u r a t i o n l , theuplinkandthedownlink
are mismatched a t the positions of the sub frames #4 and #9
(same as above). In Fig. 25, a spot-like c e l l t h a t uses t h e
configuration 0 and is allocated the uplink (UP) f o r the sub
frame #4 is surrounded by c e l l s t h a t use the configuration
5 1 and are allocated the downlink (DN) for the sub frame # 4 .
In t h i s case, a problem i n which the uplink and the downlink
are mismatched occurs l o c a l l y .
CITATION LIST
10 PATENT DOCUMENT
[0014]
Patent Document 1: J P 2010-539785 W
SUMMARY OF THE INVENTION
15 PROBLEMS TO BE SOLVED BY THE INVENTION
[00151
1t is an obj ect of the technology disclosed i n the present
d i s c l o s u r e toprovide anwireless resource allocationmethod,
a wireless resource allocation device, and a communication
20 system, which are excellent and capable of appropriately
performing an allocation of wireless resources t o reduce
interferencecausedas anuplinkandadownlinkaremismatched
between neighboring c e l l s i n a c e l l u l a r system operating
according t o the TDD scheme.
25 [0016]
It is another object ofthetechnologydisclosedinthe
presentdisclosuretoprovideanwirelessresourceallocation
method, a wireless resource allocation device, and a
communication system, which are excellent and capable of
30 appropriatelyperforminganallocationofwireless resources
t o reduce interference caused as a n u p l i n k a n d a downlink are
mismatched when different configurations are used in
neighboring cells in a cellular system in which a plurality
of configurations inwhich each of sub frames of a radio frame
is allocated for an uplink or a downlink are defined.
5
SOLUTIONS TO PROBLEMS
[0017]
The present ap~lication has been made in liqht of the
aboveproblems, and the technology set forth in a first aspect
10 is a wireless resource allocation method which includes a
rearranging step of revising a configuration arrangement of
a plurality of configurations in view of an increase in the
number of downlink sub frames or a decrease in the number of
uplink sub frames in a cellular communicationsysteminwhich
15 a plurality of configurations that differ in an uplink
allocationanda downlink allocation of sub frames in a radio
frame are defined, and a configuration switching step of
switchingconfigurationsbetweenneighboringcells according
to the arrangement revised in the rearranging step when
20 different configurations are used in the neighboring cells
in the cellular communication system.
[0018]
Accordingtothetechnologysetforthinasecondaspect
ofthepresentapplication,inthewirelessresourceallocation
25 methodaccordingtothe first aspect, intherearrangingstep,
an arrangement of at least some configurations is revised to
reduce the number of sub frames in which an uplink and a downlink
aremismatchedbetween adjacent configurations such that the
plurality of configurations are arranged preferentially in
30 theascendingorderofthenumberofdownlinksubframesrather
than the descending order ofthe number of uplink sub frames.
[0019]
Accordingtothetechnologyset f o r t h i n a t h i r d a s p e c t
of the present application, i n the wireless resource a l l o c a t i o n
methodaccordingtothe f i r s t aspect, i n t h e r e a r r a n g i n g s t e p ,
5 an arrangement of a t l e a s t some configurations is revised t o
reduce the number of sub frames i n which an uplink and a downlink
are mismatched between adjacent configurations such t h a t t h e
p l u r a l i t x of confiqurations are arrang-ed p r e f e r e n t i a l l y i n
t h e d e s c e n d i n g o r d e r o f t h e number ofuplinksub frames r a t h e r
10 thantheascendingorderofthenumberofdownlinksubframes.
[0020]
Accordingtothetechnologysetforthinafourthaspect
of the present application, the wireless resource a l l o c a t i o n
method according t o the f i r s t aspect further includes a new
15 configuration i n s e r t i n g step of i n s e r t i n g a newly defined
configuration between adjacent configurations i n which the
number of sub frames i n which the uplink and the downlink are
mismatched s t i l l increases i n the arrangement r e v i s e d i n t h e
rearranging step, and i n the configuration switching step,
20 configurations are switched between the neighboring c e l l s
according t o an arrangement i n which the newly defined
configuration is inserted.
[0021]
According t o t h e technology s e t f o r t h i n a f i f t h a s p e c t
25 ofthepresentapplication,inthewirelessresourceallocation
methodaccordingtothefourthaspect,inthenewconfiguration
i n s e r t i n g step, a configuration is newly defined such t h a t
sub framesinwhichtheuplinkandthe downlinkaremismatched
between the adjacent configurations are dispersed into sub
30 frames in which the uplink and the downlink are mismatched
between the corresponding configuration and each of the
adjacent configurations.
[00221
Accordingtothetechnologyset forth in a sixthaspect
ofthe present application, the wireless resource allocation
5 method according to the first aspect further includes an
interference avoiding step of avoiding interference between
the neighboring cells in sub frames in which the uplink and
the downlinkaremismatchedbetween the neiqhborinqcells whose
configurations are switched in the configuration switching
10 step.
[0023]
According to the technology set forth in a seventh aspect
of the present application, in the wireless resource allocation
method according to the sixth aspect, in the interference
15 avoiding step, in sub frames in which the uplink and the downlink
are mismatched between the neighboring cells, transmission
from a base station and reception in a terminal in a cell
allocated for the downlink are stopped.
[0024]
20 According tothe technology set forth in a eight aspect
of the present application, in the wireless resource allocation
method according to the sixth aspect, in the interference
avoiding step, in sub frames in which the uplink and the downlink
are mismatched between the neighboring cells, transmission
25 from a terminal and reception in a base station in a cell
allocated for the uplink are stopped, or transmission from
a base station and reception in aterminal in a cell allocated
for the downlink are stopped so that sub frames whose
transmission is stopped are not concentrated in some
30 configurations.
[0025]
According t o the technology s e t f o r t h i n n i n t h a s p e c t
of the p r e s e n t a p p l i c a t i o n , i n the wireless resource a l l o c a t i o n
method according t o the s i x t h aspect, i n t h e i n t e r f e r e n c e
avoiding step, i n sub frames i n which the uplink and the downlink
5 a r e mismatched between the neighboring c e l l s , transmission
from a terminal and reception i n a base s t a t i o n i n a c e l l
a l l o c a t e d f o r the uplink are stopped, or transmission from
a b a s e stationandrece~tioninaterminalina c e l l a l l o c a t e d
f o r the downlink are stopped according t o concentration of
10 t r a f f i c of each c e l l .
[0026]
Accordingtothetechnologyset f o r t h i n a t e n t h a s p e c t
of the p r e s e n t a p p l i c a t i o n , i n the wireless resource a l l o c a t i o n
method according t o the s i x t h aspect, i n the interference
15 a v o i d i n g s t e p , i n s u b f r a m e s i n w h i c h a c e r t a i n c e l l i n t e r f e r e s
with both adjacent c e l l s using d i f f e r e n t configurations,
transmission and reception i n a base s t a t i o n and a terminal
i n the corresponding c e l l are stopped.
[0027]
20 Further, t h e t e c h n o l o g y s e t f o r t h i n aneleventhaspect
of the present application is a wireless resource a l l o c a t i o n
device which includes
a rearranging unit t h a t revises a configuration
arrangement of a p l u r a l i t y of configurations i n view of an
25 increase i n the number of downlink sub frames or a decrease
inthenumber ofuplinksub frames i n a c e l l u l a r communication
system i n which a p l u r a l i t y of configurations t h a t d i f f e r i n
an uplink allocation and a downlink allocation of sub frames
i n a radio frame are defined, and
30 a configuration switching unit t h a t switches
configurations between neighboring c e l l s according t o the
arrangement revised in the rearranging step when different
configurations are used in the neighboring cells in the
cellular communication system.
[00281
5 Further, the technology set forth in a twelfth aspect
of the present application is a communication system that is
configuredtoreviseaconfigurationarrangementofaplurality
ofconfig_urationsinwhichanu~linkallocationandadownlink
allocation of sub frames in a radio frame are defined in view
10 of an increase in the number of downlink sub frames anda decrease
in thenumber of uplink sub frames, andswitch configurations
betweenneighboringcellsaccordingtotherevisedarrangement
when different configurations are used in the neighboring
cells.
15 [0029]
Here, a "system" refers to one in which a plurality of
devices (or functional modules for implementing a specific
function) are logicallyaggregated, andit is not consequential
practicallywhetherthe devices or the functionalmodules are
20 within a single housing.
EFFECTS OF THE INVENTION
[0030]
According to the technology disclosed in the present
25 disclosure, it is possible to provide an wireless resource
allocationmethod, awireless resourceallocationdevice, and
a communication system, which are excellent and capable of
appropriatelyperforminganallocationofwireless resources
to reduce interference causedas anuplinkand adownlinkare
30 mismatched between neighboring cells in a cellular system
operating according to the TDD scheme.
[0031]
Further, according t o the technology disclosed i n t h e
present d i s c l o s u r e , it is possible t o provide an wireless
resource a l l o c a t i o n method, a wireless resource a l l o c a t i o n
5 device, and a communication system, which are excellent and
resources t o avoid interference caused as an uplink and a
downlink aremismatchedwhendifferent conf ig-urations are used
inneighboring c e l l s i n a c e l l u l a r s y s t e m i n w h i c h a p l u r a l i t y
10 ofconfigurationsinwhicheachofsub frames o f a radio frame
is a l l o c a t e d f o r an uplink and a downlink are defined.
[0032]
In t h e c e l l u l a r communication system according t o the
technology disclosed i n the p r e s e n t d i s c l o s u r e , since
15 differentTDDconfigurationscanbeusedaccordingtoatraffic
s t a t e , the throughput of the e n t i r e system is improved.
[0033]
Other object or advantages of the technology disclosed
i n the p r e s e n t d i s c l o s u r e w i l l be c l e a r throughanembodiment
20 which w i l l be described l a t e r or t h e d e t a i l e d description based
on the appended drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0034]
25 Fig. 1 is a d i a g r a m i l l u s t r a t i n g sevenTDD configurations
0 t o 6 defined i n LTE (TS36.211 Table 4.2-2) the ascending
order o f t h e number of downlinksub frames and the descending
order of the number of uplink sub frames.
Fig. 2 is a diagram i l l u s t r a t i n g sub frames i n which
30 anuplinkandadownlinkaremismatchedbetweenconfigurations
v e r t i c a l l y adjacent t o each other i n Fig. 1.
Fig. 3 is a diagram illustrating sub frames in which
the uplink and the downlink are mismatched between
configurations vertically adjacent to each other in Fig. 20.
Fig. 4 is a diagram illustrating an example in which
5 configurations 2 and 3 which have the same number of downlink
sub frames in Fig. 1 are switched.
Fig. 5 is a diagram illustrating sub frames in which
the uplink and the downlink are mismatched between
configurations vertically adjacent to each other in Fig. 4.
10 Fig. 6 is a diagram illustrating an example of a newly
defined configuration which is inserted between
configurations 2 and 3 in the configuration arrangement
illustrated in Fig. 4.
Fig. 7 is a diagram illustrating sub frames in which
15 the uplink and the downlink are mismatched between
configurations vertically adjacent to each other in Fig. 6.
Fig. 8 is a diagram illustrating an example in which
interference is avoided by stopping a downlink transmission
of a base station through a sub frame specified to interfere
20 between configurations adjacent to each other in Fig. 7.
Fig. 9 is a diagram illustrating a state in which ABSs
are arranged in sub frames specified to interfere with each
other between configurations adjacent to each other in Fig.
7 so that ABSs are not concentrated in some configurations.
25 Fig. 10 is a diagram illustrating another example in
which ABSs are arranged in sub frames specified to interfere
witheachotherbetweenconfigurations adjacent to eachother
in Fig. 7.
Fig. 11 is a diagram illustrating an example in which
30 configurations 1 and 3 which are the same in the number of
uplink sub frames in Fig. 1 are switched.
Fig. 12 is a diagram illustrating sub frames in which
the uplink and the downlink are mismatched between
configurations vertically adjacent to each other in Fig. 11.
Fig. 13 is a diagram illustrating an example of a newly
5 defined configuration which is inserted between
configurations 1 and 3 in the configuration arrangement
illustrated in Fig. 11.
Fig. 14 is a diapr-am illustratinq-sub frames in which
the uplink and the downlink are mismatched between
10 configurations vertically adjacent to each other in Fig. 13.
L
Fig. 15 is a diagram illustrating a state in which ABSs
are arrangedin one cell in sub frames specifiedtointerfere
witheachotherbetweenconfigurations adjacenttoeachother
in Fig. 7.
15 Fig. 16 is a diagram schematically illustrating a
functionalconfigurationofa communicationdevice operating
as a base station (eNodeB) in a cellular communication system
according to the technology disclosed in the present
disclosure.
20 Fig. 17 is a diagram schematically illustrating a
functionalconfigurationofa communicationdevice operating
asaterminal(UE)inacellularcommunicationsystemaccording
to the technology disclosed in the present disclosure.
Fig. 18 is a diagram illustrating an example in which
25 10 consecutive sub frames #O to #9 ofa radio frame are allocated
as an uplink sub frame and a downlink sub frame and shared.
Fig. 19 is a diagram illustrating an example in which
a special sub frameisinsertedwhenswitching fromadownlink
to an uplink is performed between a sub frame #O and a sub
30 frame #2.
Fig. 20 is a diagram illustrating seven TDD
configurations 0 t o 6 defined i n LTE (TS36.211 Table 4.2-2 ) .
Fig. 21 is a diagram i l l u s t r a t i n g an example i n which
a rearrangement is performed t o reduce interference caused
by a mismatch of the uplink and the downlink according t o
d i f f e r e n t configurations used i n neighboring c e l l s i n Fig.
1.
Fig. 22 is a diagram i l l u s t r a t i n g sub frames i n which
the uplink and the downlink are mismatched between
configurations v e r t i c a l l y adjacent t o each other i n Fig. 21.
Fig. 23 is a diagram i l l u s t r a t i n g an example i n which
l i n k s of d i f f e r e n t d i r e c t i o n s suchas anuplinkandadownlink
are allocated a t positions of same sub frames of neighboring
eNodeBs .
Fig. 24 is a d2agram i l l u s t r a t i n g an example i n which
differentTDDconfigurationsareusedinrelativelargeareas.
Fig. 25 is a diagram i l l u s t r a t i n g an example i n which
c e l l s using d i f f e r e n t TDD configurations are l o c a t e d a
spot-like manner.
20 MODE FOR CARRYING OUT THE INVENTION
[0035]
Hereinafter, an embodiment ofthetechnologydisclosed
i n the present disclosure w i l l be described i n d e t a i l with
reference t o the appended drawings.
25 [0036]
Fig. 20 i l l u s t r a t e s the seven TDD configurations 0 t o
6 defined i n the LTE (TS36.211 Table 4.2-2). As described
above, the sub frame #O is fixedly allocated t o the downlink
i n a l l of the configurations, the sub frame #1 is fixedly
30 allocatedtothespecialsubframeinalloftheconfigurations,
the sub frame #2 is f i x e d l y a l l o c a t e d t o the uplink i n a l l
05 the configurations, and the sub frame #5 is f i x e d l y a l l o c a t e d
t o t h e downlink i n a l l o f t h e configurations. Whendifferent
TDD configurations are used i n neighboring eNodeBs, it is
l i k e l y t h a t i n the sub frame #3, #4, and #6 t o #9 other than
5 the above-mentioned sub frames, the uplink and the downlink
are mismatched, and t h u s i n t e r f e r e n c e occurs.
[0037]
The o ~ e r a t o cra n changs the r a t i o of the u ~ l i n kan d the
downlink i n the radio frame through the configuration t o be
10 used. ThefollowingTable 1 representsthenumberofdownlink
sub frames and the number of uplink sub frames of each
configuration.
[0038]
[Table 1 1
15 [0039]
It can be understood from Table 1 t h a t the seven TDD
configurations Oto 6definedintheLTE (TS36.211 Table4.2-2)
are not arrangedinorder o f t h e number of downlinksub frames
or thenumber of uplinksub frames. Here, Table 2 represents
20 t h a t the configurations Oto 6are r e a r r a n g e d i n t h e ascending
order o f t h e number of downlink sub frames and the descending
order of the number of uplink sub frames.
[0040]
[Table 21
Number of uplink sub
frames
6
4
3
4
2
1
5
Configuration
0
1
2
3
4
5
6
Number of downlink
sub frames
2
4
6
6
7
8
3
Aerp, khe= sever- conf;igrpr&-~c~~taO- -6 =d--ed-Frr
the LTE (TS36.211 Table 4.2-2) illustrated in Fig. 20 are
Configuration
0
6
1
3
2
4
5
rearranged in the ascending order of the number of downlink
5 sub frames and the descending order of the number of uplink
sub frames according to Table 2. The result is illustrated
in Fig. 1.
[0042]
When different TDD configurations are used in
[0041]
Number of downlink
sub frames
2
3
4
6
6
7
8
10 neighboring eNodeBs, the configurations are assumed to be
Number of uplink sub
frames
6
5
4
4
3
2
1
changed between neighboring eNodeBs only in the order
illustratedinFig. 1 (that is, onlyinthe order ofthe serial
numbers 0, 6, 1, 3, 2, 4, and 5) . In this case, configurations
used by neighboring eNodeBs have a combination (that is, one
15 of combinations of the serial numbers 0 and 6, 6 and 1, 1 and
3, 3 and 2, 2 and 4, and 4 and 5) of configurations vertically
adjacent to each other in Fig. 1. Betweenneighboring cells,
the ratio of the uplink and the downlink in the radio frame
gently changes.
20 [0043]
When different TDD configurations are used in
neighboring eNodeBs, it is likely that in the sub frame #3,
#4, and #6 to #9, the uplink and the downlink are mismatched,
and thus interference occurs. In Fig. 2, sub frames in which
the uplink and the downlink are mismatched between
configurations v e r t i c a l l y adjacent t o each other i n Fig. 1
a r e surrounded by thick l i n e s . Referring t o Fig. 2, between
t h e configuration0 andthe configuration 6, since t h e u p l i n k
5 andthedownlinkaremismatchedonlyinthe sub frame #9, only
one sub frame is l i k e l y t o cause i n t e r f e r e n c e . The number
of sub frames causing interference between configurations
v e r t i c a l l y adjacent t o each other in Fig. 1 ( t h a t is,
combinations of configurations of the s e r i a l numbers 0 and
10 6, 6and1, 1and3, 3and2, 2and4, and4and5) i s r e p r e s e n t e d
by the following Table 3.
[0044]
[Table 31
I Combinations of adjacent 1 umber of sub frames causing 1
[0045]
15 Referring t o Table 3, it can be understood t h a t when
configurations of combinations of the s e r i a l numbers 1 and
3, 3 and 2, and 2 and 4 are used between neighboring eNodeBs,
the number of sub frames causing interference is large.
Therefore, when d i f f e r e n t TDD configurations are used i n
20 neighboring eNodeBs, i f configurations used by neighboring
eNodeBs have one of combinations of 1 and 3, 3 and 2, and 2
and 4, there is a problem i n t h a t interference is large.
[0046]
For the sake of comparison, an example i n which the
25 above-described rearranging of the configurations is not
I configurations interference I
performed, andsub framesinwhichtheuplinkandthedownlink
aremismatchedbetween configurations verticallyadjacentto
each other in Fig. 20 are surrounded by thick lines is
illustrated in Fig. 3. The following Table 4 represents the
5 number of sub frames causing interference between
configurations vertically adjacent to each other in Fig. 20
(combinations of configurations of the serial numbers 0 and
1, 1 and 2, 2 and 3, 3 and 3, 4 and 5, and 5 and 6).
[0047]
10 [Table 41
I Combinations of adjacent l~umber of sub frames causing1
[0048]
Referring to Table 4, it can be understood that when
configurations of a combination of the serial numbers 2 and
3 or 5 and 6 are used in neighboring cells, the number of sub
15 frames causing interference is large. When Fig. 2 and Table
3 are compared with Fig. 3 and Table 4, respectively, as the
configurations are rearranged in the ascending order of the
number of downlink sub frames and the descending order of the
number of uplink sub frames, the number of sub frames causing
20 interference between adjacent configurations decreases.
Since a maximum number of sub frames causing interference
between adjacent configurations is reduced through the
rearrangement ofthe configurations, thethroughputofa cell
may not be significantly reduced.
25 [0049]
configurations
0-1
1-2
2-3
3-4
4-5
5-6
interference
2
2
4
1
1
5
Until now, t h e d e s c r i p t i o n has been made focusing on
a sub frame causing interference i n a radio frame whendif f erent
TDD configurations are used i n neighboring eNodeBs. In the
following, atechniqueofavoidinginterferenceinasub frame
5 i n which interference occurs w i l l be f u r t h e r described.
[00501
In the past, techniques of removing interference when
interference occurs by a method of adiustinq transmission
output of a transmitter causing interference, a method of
10 stopping transmission of a transmitter, a method of dividing
sub c a r r i e r s i n the frequency direction and performing
multiplexing, or the likehavebeen known. Onthe other hand,
an embodiment disclosed i n the present disclosure does not
focus a t t e n t i o n on a method of removing interference. For
15 example, i n the 3GPP Re1 10, i n order t o reduce influence of
interferencebetweenneighboringcells, ABS (AlmostBlankSub
frame) is specified as I C I C ( I n t e r c e l l Interference
Coordination). Amethod of further avoidinginterference an
ABS w i l l be described below.
20 [00511
An almost blank sub frame (ABS) is a technique of stopping
transmission of user data, and for example, a s p e c i f i c sub
frame of an eNodeB causing interference is used as an ABS.
Evenwhen transmissionof u s e r d a t a s t o p s , a reference signal
25 s l i g h t l y remains. A method of stopping the reference signal
has been proposed as well. Ultimately, the ABS is a simple
interferenceavoidingtechniqueofstoppingtransmissionwhen
interference occurs.
[00521
30 Referring back t o Table 3, when the configurations are
rearranged in view of an increase in the number of downlink
sub frames and a decrease in the number of uplink sub frames,
the number of sub frames causing interference increases in
the combinations ofthe configurations ofthe serial numbers
1and3, 3 and2, and2 and4. WhenanABSisusedasinter-cell
interference coordination (ICIC), any one of neighboring
eNodeBs stops transmission ina sub frame causing interference.
Therefore, whenany oneof combinations ofthe configurations
of the serial numbers 1 and 3, 3 and 2, and 2 and 4 is used
in neighboring eNodeBs, the throughput of a cell is
significantly reduced.
100531
Fig. 1 and Table 2 represent a result of rearranging
the seven TDD configurations 0 to 6 defined in the LTE (TS36.211
Table 4.2-2) in the ascending order of the number of downlink
sub frames and the descending order of the number of uplink
subframes. Here, anattempt torearrange the configurations
0 to 6 preferentially in the ascending order of the number
of downlink sub frames rather than the descending order of
thenumber of uplinksub frameshasbeenmade. Specifically,
the configurations 2 and 3 which are the same in the number
of downlink sub frames in Fig. 1 and Table 2 are switched as
illustrated in Fig. 4 and the following Table 5. In the example
illustrated in Table 5, the arrangement is made in the ascending
orderofthenumberofdownlinksubframeswhilethedescending
order of the number of uplink sub frames is not kept.
[0054]
[Table 51
Number of uplink sub
frames
6
5
4
Configuration
0
6
1
Number of downlink
sub frames
2
3
4
[0055]
InFig. 5, subframesinwhichtheuplinkandthedownlink
aremismatchedbetweenconfigurations v e r t i c a l l y a d j a c e n t t o
each other i n Fig. 4 are surrounded by thick l i n e s . The
5 following Table 6 r e p r e s e n t s t h e number of sub frames causing
interferencebetween the configurations v e r t i c a l l y adjacent
t o eachother i n Fig. 4 ( t h a t is, combinations of configurations
of the s e r i a l numbers 0 and 6, 6 and 1, 1 and 2, 2 and 3, 3
and 4, and 4 and 5 ) .
10 [0056]
[Table 61
[00571
When Fig. 2 and Table 3 are compared with Fig. 5 and
Table 6, respectively, as the configurations 0 t o 6 are
15 rearrangedpreferentiallyintheascendingorderofthenumber
of downlink sub frames r a t h e r than the descending order of
the number of uplink sub frames, the number of sub frames causing
interference may be f u r t h e r reduced.
[0058]
Combinations of adjacent
configurations
0-6
6-1
1-2
2-3
3-4
4-5
20 However, r e f e r r i n g t o Table 6, when a combination of
the configurations 2 and 3 is used i n neighboring eNodeBs,
the number of sub frames causinginterference is s t i l l large,
Number of sub frames causing
interference
1
1
2
4
1
1
t h a t is, four. Therefore, when an ABS is used as I C I C and
cells using the configurations 2 and 3 are adjacent t o each
other, an eNodeB of any one c e l l stops transmission i n a sub
frame c a u s i n g i n t e r f e r e n c e , andthus the throughput of a c e l l
5 is s i g n i f i c a n t l y reduced.
[00591
The reason why t h e r e a r e many sub frames causing
interference between the confiqurations 2 and 3 i n the
arrangement of the configurations i l l u s t r a t e d i n Fig. 4 is
10 because uplink a l l o c a t i o n s and downlink a l l o c a t i o n s of sub
frames s i g n i f i c a n t l y change between the two configurations.
I n t h i s regard, a method of defining a new configuration i n
whichuplinkallocationsanddownlinkallocationsofsubframes
gently change fromthe configuration 2 or uplink a l l o c a t i o n s
15 and downlink allocations of sub frames gently change t o the
configuration 3, a n d i n s e r t i n g t h e new configurationbetween
theconfigurations2and3isconsidered. Asthenewlydefined
configuration is i n s e r t e d between the configurations 2 and
3, it is expected t h a t a phenomenon t h a t the uplink and the
20 downlinkaremismatchedismitigated,thenumberofsubframes
which are subjected t o ABSs i n each c e l l is reduced, and
d e t e r i o r a t i o n i n the throughput of each c e l l is prevented.
[00601
Fig. 6 i l l u s t r a t e s an example in which a new
25 configuration is defined and inserted between the
configurations 2 and 3 i n the configuration arrangement
i l l u s t r a t e d i n F i g . 4. Basically, aconfigurationtobenewly
defined is one i n which uplink and downlink allocations of
sub frames are decided so t h a t four sub frames inwhichamismatch
30 of the uplink and the downlink, t h a t is, interference occurs
between the configurations 2 and 3 undergo two interferences
between the configuration 2 and the new configuration and
between the new configuration and the configuration 3. Sub
frames which interfere with each other between the
configurations 2 and 3 are dispersed into sub frames which
5 interfere with each other between each of the configurations
2 and 3, and the newly defined configuration.
[ 00 61 ]
Therefore,sinceu~linkanddownlinkallocationsoffour
sub frames that interfere with each other between the
10 configurations 2 and 3 have 4C2 (=6) combinations, there are
six types of configurations including a configuration
illustrated in Fig. 6 as configurations to be newly configured.
Preferably, among the six types, a new configuration is defined
so that downlink and the uplink sub frame are most seamlessly
15 connected from the configuration 2 to the configuration 3.
A very ideal configuration depends even on an arrangement of
an ABS. An arrangement of an ABS will be described later.
[0062]
Fig. 7 illustrates sub frames in which the uplink and
20 thedownlinkaremismatchedbetweenconfigurationsvertically
a d j a c e n t t o e a c h o t h e r i n F i g . 6 are surroundedbythicklines.
The following Table 7 represents the number of sub frames
causing interference between configurations vertically
adjacent to each other in Fig. 6.
25 [0063]
[Table 71
Combinations of adjacent
configurations
0-6
6-1
1-2
2-new configuration
new configuration-3
Number of sub frames causing
interference
1
1
2
2
2
[0064]
When Fig. 5 and Table 6 are compared with Fig. 7 and
Table 7, respectively, it can be understood t h a t the number
of sub frames causing interference is f u r t h e r reduced by
5 i n s e r t i n g anewlydefined configuration. Referring t o Table
7, a maximum of the number of sub frames t h a t i n t e r f e r e s with
eackat.herbetweerr aezcerrP confzgura-tions is two; an+
d e t e r i o r a t i o n i n the throughput of each c e l l canbe prevented
by reducing the number of sub frames which are subjected t o
10 ABSs i n each c e l l .
[0065]
As described above, when d i f f e r e n t configurations are
set inneighboring c e l l s , sub framesthat i n t e r f e r e witheach
other occur because the uplink and the downlink are mismatched.
15 When it is possible t o specify sub frames t h a t i n t e r f e r e with
each o t h e r , a decision of a c e l l in which transmission of a
sub frame is t o be stopped, t h a t is, a s e t t i n g of an ABS is
problematic. It is because when an ABS is concentrated i n
one of neighboring c e l l s , the throughput of the c e l l
20 s i g n i f i c a n t l y d e t e r i o r a t e s .
[0066]
Fig. 8 i l l u s t r a t e s an example i n which interference is
avoided by stopping the transmission of an eNodeB of the
downlink, t h a t is, arranging an ABS in sub frames specified
25 t o have a mismatched uplink or downlink ( t h a t is, i n t e r f e r e
witheachother)betweenconfigurationsadjacenttoeachother
i n F i g . 7. InFig. 8, portionsinwhichdownlinktransmission
of a base s t a t i o n is stopped ( t h a t is, an ABS is arranged)
are indicated by hatching.
[0067]
When a s e t t i n g of an ABS is made so t h a t downlink
transmission of an eNodeB is stopped, ABSs a r e l i k e l y t o be
concentrated i n one of neighboring c e l l s . I n the example
5 i l l u s t r a t e d i n Fig. 8, the number of sub frames i n which an
ABS is arranged i n each configuration is represented i n the
followingTable8. I n t h i s c a s e , sincetheABSis concentrated
i n the config-uration 2, the throughput of a c e l l t o which t h e
configuration 2 is s e t is s i g n i f i c a n t l y reduced. Further,
10 it is u n d e r s t o o d t h a t t h e r a t i o o f t h e downlinkandtheuplink
is not gently changed i n the order of the configurations
i l l u s t r a t e d i n Fig. 8.
[Table 81
15 [0069]
In t h i s regard, a method of allocating an ABS so t h a t
ABSs are not concentrated i n some configurations is f u r t h e r
reviewed. In the example i l l u s t r a t e d i n Fig. 8, an ABS is
arranged i n a c e l l allocated t o the downlink i n a sub frame
20 i n which interference has occurred. On the other hand, a
s e t t i n g can be made so t h a t ABSs are not concentrated i n some
configurations by allowing an ABS t o be arranged even i n a
c e l l allocated t o the uplink. Therefore, i n sub frames i n
which the uplink and the downlink are mismatched between
Configuration
0
6
1
2
new configuration
3
4
2 Number of sub frames i n which
ABS is arranged
0
1
1
3
0
2
1
configurations adjacent to each other, the ABS can be set for
both the uplink and the downlink.
[0070]
Fig. 9illustrates anexampleinwhichABSs are arranged
5 in sub frames specified to have amismatcheduplinkanddownlink
(thatis,tointerferewitheachother)betweenconfigurations
adjacent to each other in Fig. 7 so that the ABSs are not
concentrated in some config-urations. In Fig-. 9, portions in
which the ABSs are arranged are indicated by hatching. In
10 the example illustrated in Fig. 8, an ABS is arranged only
in a downlink sub frame, but a setting can be made so that
ABSs are not concentrated in some configurations by flexibly
arranging an ABS either uplink or downlink sub frame as
illustrated in Fig. 9. The following Table 9 represents the
15 number of sub frames in which an ABS is arranged in each
configuration in the example illustrated in Fig. 9.
[0071]
[Table 91
[0072]
20 Further, when different configurations are used in
neighboring cells, if traffics of each cell are imbalanced,
an ABS may be set in each sub frame in which interference has
occurred according to the imbalance.
[0073]
configuration
0
6
1
2
new configuration
3
4
5
Number of sub frames in which
ABS is arranged
1
- 1
1
1
2
1
1
1
In the examples illustrated in Figs. 8 and 9, in sub
frames in which the uplink and the downlink are mismatched
between configurations adjacent to each other, an ABS is set
to any one cell. As an ABS is set, interference can be avoided,
and the ABS can be dispersedly arranged in the respective
configurations, but in any case, when the ABS is arranged,
the throughput of a cell deteriorates. Therefore, it is
desirable to reduce the number of ABSs to be set.
[0074]
Fig. 10 illustrates another example in which ABSs are
arranged in sub frames specified to have interference with
each other between configurations adjacent to each other in
Fig. 7. Further, in the example illustrated in Fig. 10, the
number of sub frames in which an ABS is arranged in each
configuration is represented by the following Table 10.
[0075]
[Table 101
[0076]
Fig.10illustrates anexampleinwhichanABSis allowed
20 to be set to both the uplink and the downlink, similarly to
Fig. 9. As can be seen from Fig. 7, in the configuration
arrangement illustratedin Fig. 6, interference occurs in the
sub frames #3 in three configurations, which are the
configurations 1, 2, and the newly defined configuration.
Configuration
0
6
1
2
new configuration
3
4
5
Number of sub frames in which
ABS is arranged
1
1
2
0
3
1
1
1
When both c e l l s adjacent t o a c e l l using the configuration
2 use the configuration 1 and a newly defined configuration,
respectively, the c e l l using the configuration 2 i n t e r f e r e s
with both adjacent c e l l s i n the sub frame #3. In the example
5 i l l u s t r a t e d i n Fig. 10, ABSs are arranged i n both adjacent
c e l l s i n order t o avoid interference i n sub frames i n which
a c e r t a i n c e l l i n t e r f e r e s with both of the adjacent c e l l s .
In other words, since two adjacent c e l l s are s a c r i f i c e d i n
order t o r e l i e v e a single c e l l of interference, and thus it
10 is not e f f i c i e n t .
[0077]
Therefore, i n sub frames i n which a c e r t a i n c e l l
i n t e r f e r e s with both adjacent c e l l s using d i f f e r e n t
configurations, by arranging an ABS i n the c e l l r a t h e r than
15 both adjacent c e l l s , and thus interference between both
adjacent c e l l s canbe avoided, and thus it ismorepreferable.
Unlike Fig. 10, i n the example i l l u s t r a t e d i n Fig. 9, an ABS
is arranged i n the sub frame #3 of the configuration 2, and
interference canbe avoidedbetweenthe sub frames #3 of both
20 of the configuration 1 and the newly defined configuration
which are adjacent t o each other, and thus it is more preferable.
[0078]
Additionally, as a configuration is newly defined, the
number of ABSs t o be s e t can be reduced.
25 [0079]
Fig. 4 i l l u s t r a t e s the r e s u l t of revising the
configuration arrangement so t h a t the configurations are
arrangedinboththeascendingorder o f t h e number ofdownlink
sub frames and the descending order of the number of uplink
30 sub frames, and then revising the configuration arrangement
s o t h a t the configurations are arrangedpreferentiallyinthe
ascending order of the number of downlink sub frames rather
than the descending order of the number of uplink sub frames.
[00801
On the contrary, Fig. 11 illustrates a result of revising
5 the configuration arrangement sothat the configurations are
arrangedpreferentiallyinthe descendingorderofthenumber
of uplink sub frames rather than the ascending order of the
number of downlinksub frames. Specifically, as illustrated
in Fig. 11 and the following Table 11, the configurations 2
10 and 4 which are the same in the number of downlink sub frames
in Fig. 1 and Table 2 are switched.
[0081]
[Table 111
[00821
15 Fig. 12 illustrates an example in which sub frames in
which the uplink and the downlink are mismatched between
configurations vertically adjacent to each other in Fig. 11
are surrounded by thick lines. The following Table 12
represents the number of sub frames causing interference
20 between configurations vertically adjacent to each other in
Fig. 11 (in combinations of configurations having serial
numbers 0 and 6, 6 and 1, 1 and 3, 3 and 4, 4 and 2, and 2
and 5. )
[00831
Number of uplink sub
frames
6
5
4
3
2
2
1
Configuration
0
6
1
3
4
2
5
Number of downlink
sub frames
2
3
4
6
7
6
8
[Table 121
[0084]
When Table 12 is compared with Table 3, it can be
understoodthatthen~mberofs ub frames causinginterference
is reduced. For example, inTable 3, there are two combinations
of adjacent configurations i n which the number of sub frames
c a u s i n g i n t e r f e r e n c e i s four, whereas inTable12, thenumber
of combinations of adjacent configurations i n which the number
of sub frames causing interference is reduced t o one.
Therefore, the same e f f e c t s canbe obtainedevenbythemethod
of newly rearranging the configurations so t h a t the
configurations are arrangedpreferentiallyinthedescending
order of the number of uplink sub frames r a t h e r than the
ascending order of the number of downlink sub frames.
[0085]
Fig. 13 i l l u s t r a t e s an example i n which a new
configuration is defined and i n s e r t e d between the
configurations 1 and 3 i n the configuration arrangement
i l l u s t r a t e d i n Fig. 11. Basically, the configuration t o be
newlydefinedis one inwhichuplinkanddownlinkallocations
of sub frames are decided so t h a t four sub frames i n which
amismatch of the uplink and the downlink, t h a t is, interference
occurs between the configurations 1 and 3 undergo two
interferences between the configuration 1 and the new
configuration and between the new configuration and the
Combinations of adjacent
configurations
0-6
6-1
1-3
3-4
4-2
2-5
Number of sub frames,causing
i n t e r f e r e n c e
1
1
4
1
3
2
configuration 3.
[0086]
Sinceuplinkanddownlinkallocationsoffoursubframes
that interfere with each other between the configurations 1
5 and 3 have 4C2 ( = 6) combinations, there are six types of
configurations including a configurationillustratedin Fig.
13 as configurations to be newly configured. Preferably,
amonq the six types, a new config-uration is defined so that
downlink and the uplink sub frame are most seamlessly connected
10 from the configuration 1 to the configuration 3.
[0087]
Fig. 14 illustrates an example in which sub frames in
which the uplink and the downlink are mismatched between
configurations vertically adjacent to each other in Fig. 13
15 are surrounded by thick lines. The following Table 13
represents the number of sub frames causing interference
between configurations vertically adjacent to each other in
Fig. 13.
[0088]
20 [Table 131
[0089]
Fig. 15 illustrates an example in which interference
is avoidedinsub frames specifiedtohave amismatcheduplink
and downlink (to interfere with each other) between
Combinations of adjacent.
configurations
0-6
6-1
1-new configuration
new configuration-3
3-4
4-2
2-5
Number of sub frames causing
interference
1
1
2
2
1
3
2
configurations adjacent t o each other by arranging ABSs i n
Fig. 1 4 . In Fig. 15, portions i n which an ABS is arranged
a r e indicated by hatching. In Fig. 15, ABS are arranged not
t o be concentrated on some configuration. Further, i n sub
5 frames i n which a c e r t a i n c e l l i n t e r f e r e s with both adjacent
c e l l s using d i f f e r e n t configurations, an ABS is arranged is
arranged i n the c e l l (same as above).
LO0901
TheexamplesillustratedinFig. 4 andTable5 represent
10 a r e s u l t of r e v i s i n g t h e configurationarrangement according
t o the rule i n which the configurations are arranged
p r e f e r e n t i a l l y i n the ascending order of the number of downlink
sub frames. Further, the examples i l l u s t r a t e d i n Fig. 11and
Table 11 represent r e s u l t s of revising the configuration
15 arrangement a c c o r d i n g t o t h e r u l e inwhich the configurations
are arranged p r e f e r e n t i a l l y i n the descending order of the
number of uplink sub frames. On the other hand, another method
of revising a configuration arrangement is considered other
than rule i n which the ascending order of the number of downlink
20 sub frames is p r e f e r e n t i a l l y considered or rule i n which the
descending order of the number of downlink sub frames is
p r e f e r e n t i a l l y considered. It is because t h a t the purpose
of reducing interference caused as d i f f e r e n t configurations
are used i n neighboring c e l l s and thus the uplink and the
25 downlink aremismatchedis not equivalent t o t h e above rules.
Fig. 21 and the following Table 14 i l l u s t r a t e s an example of
a r e s u l t of revising the arrangement t o reduce interference
caused as d i f f e r e n t configurations are used i n neighboring
c e l l s and thus the uplink and the downlink are mismatched
30 without being limited t o the above r u l e s .
[0091]
[Table 14.1
[ 0 099F
Fig. 22 illustrates an example in which sub frames in
which the uplink and the downlink are mismatched between
5 configurations vertically adjacent to each other in Fig. 21
are surrounded by thick lines. The following Table 15
represents the number of sub frames causing interference
between configurations vertically adjacent to each other in
Fig. 21 (that is, combinations of configurations having the
10 serial numbers 0 and 6, 6 and 1, 1 and 2, 2 and 5, 5 and 4,
and 4 and 3).
[0093]
[Table 151
Configuration
0
6
1
2
5
4
3
[0094]
15 For example, according to Table 14, in an area adjacent
toanareausingthe configurationl, eitherthe configuration
6 orthe configuration2isused, butthe configuration 6which
is smaller in the number of sub frames causing interference
is selected with reference to Table 15. Further, when the
Number of downlink
sub frames .
2
3
4
6
8
7
6
Combinations of adjacent
configurations
0-6
6-1
1-2
2-5
5-4
4-3
Number of uplink sub
frames
6
5
4
3
1
2
4
Number of sub frames causing
interference
1
1
2
2
1
1
configurations are the same i n the number of sub frames causing
interference, selectionmaybemade according t o ademand f o r
wireless resources from the area. For example, when a
configuration t o be used i n an area adjacent t o an area using
5 the c o n f i g u r a t i o n 6 i s s e t , i f adownlinksub frame is i n g r e a t
demand i n the a.rea, the configuration 1 is selected r a t h e r
than the configuration 0.
100951
In the c e l l u l a r communication system, a s e t t i n g of a
10 configuration and a s e t t i n g of an ABS i n each c e l l using any
configuration described above a r e p r a c t i c a l l y performed by
anMME (mobilemanagemententity) whichacorenetworkdevice.
[0096]
For example, the MME performs a process of rearranging
15 the seven TDD configurations 0 t o 6 defined i n the LTE (TS36.211
Table 4.2-2) i l l u s t r a t e d i n Fig. 20 throughthe above-described
procedure, obtains the arrangement i l l u s t r a t e d i n Fig. 1 (Table
2 ) , Fig. 4 (Table 5 ) , Fig. 6, Fig. 11 (Table ll), Fig. 13,
and Fig. 21 (Table 1 4 ) , and s t o r e s the arrangement i n a t a b l e
20 or the l i k e . Further, theMMEperforms anABS s e t t i n g of each
subframewhendifferentconfigurationsaresetinneighboring
c e l l s , and stores information of an ABS s e t t i n g position.
Alternatively, the configuration rearrangement process may
be performed by a device other than the MME, and the MME may
25 s t o r e t h e t a b l e i n which the arrangement i l l u s t r a t e d i n Fig.
1 (Table 2 ) , Fig. 4 (Table 5 ) , Fig. 6, Fig. 11 (Table 11) ,
Fig. 13, andFig. 21 (Table14) isdescribed, whichis obtained
from an external device. Then, the MME may allocate a
configuration used by a c e l l t o each base s t a t i o n (eNodeB)
30 with reference t o the t a b l e . Further, an ABS s e t t i n g of each
subframewhendifferentconfigurationsaresetinneighboring
cells may be also performed by a device other than the MME,
and the MME may hold obtained ABS setting information.
[0097]
In the cellular communication system according to the
5 technology disclosed in the present disclosure, a TDD
configurationisconsideredtobeastaticsettingtoacertain
extent. In other words, when a setting is made once, a system
is operated with the same setting for about one year.
Specifically, the operator sets a designed TDD environment
10 to an eNodeB through an MME. Then, the eNodeB is considered
to set the information to eachterminal (UE) locatedin a cell
throughsysteminformationordedicatedsignaling. However,
it is difficult to deny a possibility that a Het-Net
(heterogeneousnetwork) environmentwillmakeaprogress, and
15 a systeminwhicha TDDconfigurationis followeddynamically
according to a change in traffic will appear.
[0098]
Fig. 16 schematically illustrates a functional
configuration of a communication device operating as a base
20 station (eNodeB) ina cellularcommunicationsystemaccording
to the technology disclosed in the present disclosure.
[0099]
A configuration holding unit 1607 holds information
related to a TDD configuration which is set according to a
25 control signal from an MME (not illustrated) and to be used
in its own cell. An ABS setting position holding unit 1608
holds a position of a sub frame which is set according to a
control signal from an MME in the configuration to be used
in its own cell and subjected to an ABS.
30 [OlOOI
The base station may not set a configuration to be used
within its own c e l l according t o a control signal from an MME
but may s e t a configuration t o be used i n a c e l l by its own
base s t a t i o n and cause the s e t configuration t o be held i n
the configuration holding u n i t 1607. For example, the base
s t a t i o n m a y h o l d a t a b l e i n w h i c h t h e arrangements i l l u s t r a t e d
i n Fig. 1 (Table 2 ) , Fig. 4 (Table 5 ) , Fig. 6, Fig. 11 (Table
11) , Fig. 13, Fig. 21 (Table 1 4 ) , and the l i k e are described,
and when a confiquration beinq used i n a neiqhborinqcell is
acquiredthroughcommunicationbetweenbasestations,thebase
s t a t i o n may s e t a configuration t o be used i n a c e l l by its
own base s t a t i o n with reference t o the table.
[0101]
Further, the base s t a t i o n may not s e t a position of a
sub framewhichis subjectedtoanABSinitsowncellaccording
t o a control signal from an MME but may determine whether it
subject an ABS i n each sub frame i n its own c e l l and cause
t h e d e t e r m i n a t i o n r e s u l t t o b e h e l d i n t h e A B S s e t t i n g p o s i t i o n
holding unit 1608. For example, the base s t a t i o n may hold
a t a b l e i n w h i c h t h e a r r a n g e m e n t s i 1 l u s t r a t e d i n F i g . 1 (Table
2 ) , Fig. 4 (Table 5), Fig. 6, Fig. 11 (Table ll), Fig. 13,
Fig. 21 (Table 1 4 ) , and the l i k e are described, and when a
configuration being used i n a neighboring c e l l is acquired
throughcommunicationbetweenbase s t a t i o n s , thebase s t a t i o n
may compare the configuration being used i n the neighboring
c e l l with a configuration t o be used i n its own c e l l with
reference t o t h e t a b l e , determine whether an ABS is t o be s e t
t o each sub frame i n its own c e l l and cause the determination
r e s u l t to be held i n the ABS s e t t i n g position holding unit
1608.
[01021
The base s t a t i o n performs uplink or downlink
communication through each sub frame of a radio frame according
to a TDD configurationheldinthe configurationholding unit
1607.
[0103]
5 The base station receives user data to be transmitted
to a terminal (UE) in its own cell through the downlink from
a serving gateway. An ABS inserting unit 1605 inserts an ABS
to a position of a sub frame held in the ABS setting position
holding unit 1608 in each of a PDCCH (Phy Downlink Control
10 Channel) and a PDSCH (Phy Downlink Shared Channel).
ADAconvertingunit 1603 converts adigital transmission
signal into an analog transmission signal. Then, an RF
transceiving unit 1602 up-converts the analog transmission
15 signal to anRFband, performs power amplification, and emits
a resultant signal to space through an antenna 1601.
[0105]
Further, when the base station receives anuplink signal
transmitted from a terminal (UE) through the antenna 1601,
20 theRFtransceivingunit1602performslownoiseamplification
and down-conversion, and an AD converting unit 1604 performs
digital conversion.
[0106]
AnABSdetectingunit1606detects anABS fromtheuplink
25 digital signal at a position of a sub frame held in the ABS
setting position holding unit 1608 in each of a PUCCH (Phy
Uplink Control Channel) and a PUSCH (Phy Uplink Shared
Channel) .
[01071
30 Fig. 17 schematically illustrates a functional
~onfigurat~onoa fc ommunicationdevice operating as a terminal
(UE) in a cellular communication system according to the
technology disclosed in the present disclosure.
[0108]
When the terminal (UE) is notifiedof information related
5 to a TDD configuration through signaling from a base station
(eNodeB) controlling its own station, the terminal (UE) holds
the TDD configuration in a configuration holding unit 1707.
Further, when a position of a sub frame which is subjected
to anABS in a configuration tobe usedinthe cell is notified
10 through signaling from a base station, the position is hold
in an ABS setting position holding unit 1708.
[0109]
The terminal performs uplink or downlink communication
in each sub frame of a radio frame according to a TDD
15 configuration held in the configuration holding unit 1707.
[OllO]
The terminal receives user data to be transmitted to
a base station through the uplink from an upper layer such
as an application. An ABS inserting unit 1705 inserts an ABS
20 i n t o a p o s i t i o n o f a s u b f r a m e h e l d i n t h e A B S settingposition
holding unit 1708 in each of a PUCCH and a PUSCH.
[Olll]
ADAconvertingunit 1703 converts a digital transmission
si.gnal into an analog transmission signal. Then, an RE
25 transceiving unit 1702 up-converts the analog transmission
signal to an RE band, performs power amplification, and emits
a resultant signal to space through an antenna 1701.
[0112]
Further, when the terminal receives a downlink signal
30 transmitted fromabase station through the antenna1701, the
RE transceiving unit 1702 performs low noise amplification
and down-conversion, and an AD converting unit 1704 performs
digital conversion.
[0113]
AnABS detectingunit1706detects anABS fromtheuplink
5 digital signal at a position of a sub frame held in the ABS
setting position holding unit 1608 in each of a PDCCH and a
PDSCH.
LO1141
The technology disclosedinthe present disclosure can
10 have the following configurations.
(1) A wireless resource allocation method, including,
a rearranging step of revising a configuration
arrangement of a plurality of configurations in view of an
increase in the number of downlink sub frames or a decrease
15 inthenumberofuplinksubframesinacellularcommunication
system in which a plurality of configurations that differ in
an uplink allocation and a downlink allocation of sub frames
in a radio frame is defined, and
a configuration switching step of switching
20 configurations between neighboring cells according to the
arrangement revised in the rearranging step when different
configurations are used in the neighboring cells in the
cellular communication system.
(2) The wireless resource allocation method according
25 to (I),
wherein, in the rearranging step, an arrangement of at
least some configurations is revised to reduce the number of
sub frames in which an uplink and a downlink are mismatched
between adjacent configurations such that the plurality of
30 configurations are arrangedpreferentially in the ascending
order of the number of downlink sub frame rather than the
descending order of the number of uplink sub frames.
(3) The wireless resource allocation method according
to (11,
wherein, in the rearranging step, an arrangement of at
5 least some configurations is revised to reduce the number'of
sub frames in which an uplink and a downlink are mismatched
between adjacent configurations such that the plurality of
confiqurations are arranqedpreferentiallyinthe descendinq
order of the number of uplink sub frame rather than the ascending
10 order of the number of downlink sub frames.
(4) The wireless resource allocation method according
to any one of (1) to ( 3 ) , further includes
anewconfigurationinsertingstep of inserting anewly
defined configuration between adjacent configurations in
15 which the number of sub frames in which the uplink and the
downlink are mismatched still increases in the arrangement
revised in the rearranging step,
wherein, in the configuration switching step,
configurations are switched between the neighboring cells
20 according to an arrangement in which the newly defined
configuration is inserted.
(5) The wireless resource allocationmethod according
to (411
wherein, in the new configuration inserting step, a
25 configuration is newly defined such that sub frames in which
the uplink and the downlink aremismatched between the adjacent
configurations are dispersed into sub f~ames in which the
uplink and the downlink are mismatched between the
configuration and each of the adjacent configurations.
30 (6) The wireless resource allocation method according
to any one of (1) to ( 5 ) , further includes
an interference avoiding s t e p o f a v o i d i n g i n t e r f e r e n c e
between the neighboring c e l l s i n sub frames i n which the uplink
andthe downlinkaremismatchedbetweentheneighboringcells
whose configurations are switched i n the configuration
5 switching s t e p .
(7) The wireless resource a l l o c a t i o n method according
t o (61,
wherein,in t h e i n t e r f e r e n c e avoidinqstep, i n sub frames
i n which the uplink and the downlink are mismatched between
10 the neighboring c e l l s , transmission from a base s t a t i o n and
reception i n a terminal i n a c e l l allocated for the downlink
are stopped.
(8) The wireless resource a l l o c a t i o n method according
t o (611
wherein, i n the interference avoiding step, insub frames
i n which the uplink and the downlink are mismatched between
the neighboring c e l l s , transmission from a terminal and
reception i n a b a s e s t a t i o n i n a c e l l allocated f o r t h e uplink
arestopped, ortransmission f r o m a b a s e s t a t i o n a n d r e c e p t i o n
20 i n a t e r m i n a l i n a cellallocatedforthedownlinkare stopped
so t h a t sub frames whose transmission is stopped are not
concentrated i n some configurations.
(9) The wireless resource allocationmethod according
t o ( 6 ) ,
25 wherein, i n the interference avoiding step, i n sub frames
i n which the uplink and the downlink are mismatched between
the neighboring c e l l s , transmission from a terminal and
reception i n a b a s e s t a t i o n in a c e l l allocated f o r t h e uplink
arestopped, ortransmission fromabasestationandreception
30 inaterminalinacellallocatedforthedownlinkare stopped
according to concentration of t r a f f i c of each c e l l .
(10) Thewireless resource allocationmethodaccording
t o (61,
wherein, i n the interference avoiding step, i n sub frames
i n which a c e r t a i n c e l l i n t e r f e r e s with both adjacent c e l l s
5 using d i f f e r e n t configurations, transmission and reception
i n a base s t a t i o n and a terminal i n the c e l l are stopped.
(11) A wireless resource a l l o c a t i o n device, including
a r e a r r a n q i n q u n i t t h a t revises a confiquration
arrangement of a p l u r a l i t y of configurations i n view of an
10 increase i n the number of downlink sub frames or a decrease
inthenumberofuplinksubframesina c e l l u l a r communication
system i n which a p l u r a l i t y of configurations t h a t d i f f e r i n
an uplink allocation and a downlink allocation of sub frames
i n a radio frame are defined, and
a configuration switching unit t h a t switches
configurations between neighboring c e l l s according t o the
arrangement revised i n the rearranging step when d i f f e r e n t
configurations are used i n the neighboring c e l l s i n the
c e l l u l a r communication system.
( 1 2 ) Acommunicationsystemthatis configuredtorevise
a configuration arrangement of a p l u r a l i t y of configurations
i n which an uplink allocation and a downlink allocation of
sub frames in a radio frame are defined in view of an increase
i n the number of downlink sub frames and a decrease i n the
numberofuplinksubframes, andswitchconfigurationsbetween
neighboring c e l l s according t o the revised arrangement when
d i f f e r e n t configurations are used i n the neighboring c e l l s .
INDUSTRIAL APPLICABILITY
30 [01151
Thetechnologydisclosedinthe present disclosure has
been described in detail with reference to a specific
embodiment. However, it is obvious that a person skilled in
the art can make modifications or substitutions on the above
embodiment within the scope not departing from the gist of
5 the technology disclosed in the present disclosure.
[0116]
Thepresentdisclosurehasbeendescribedinconnection
with the embodiment applied to a cellular communication system
conforming to the LTE designed by the 3GPP, but the gist of
10 the technology disclosed in the present disclosure is not
limited to this example. Interference caused as the uplink
andthedownlinkaremismatchedwhendifferentconfigurations
are used in neighboring cells can be avoided by similarly
applying the present technology to various cellular
15 communication systems inwhich aplurality of configurations
in which an uplink allpcation and a downlink allocation of
sub frames in a radio frame are different from each other are
defined.
[0117]
20 In short, the present technology is disclosed as an
embodiment, andthus thedescriptionofthepresentdisclosure
is not interpreted to be limited. The gist of the present
technology should be determined in consideration of the
appended claims.
25
REFERENCE SIGNS LIST
[01181
1601 Antenna
1602 RF transceiving unit
30 1603 DA converting unit
1604 AD converting unit
ABS inserting unit
ABS detecting unit
Configuration holding unit
ABS setting position holding
Antenna
RF transceiving unit
DA converting unit
AD convertinq unit
ABS inserting unit
ABS detecting unit
unit
Configuration holding unit
ABS setting position holding unit

CLAIMS b
1. A wireless resource allocation method, comprising:
a rearranging step of revising a configuration
5 arrangement of a plurality of configurations in view of an
increase in the number of downlink sub frames or a decrease
inthenumber of uplinksub-frames ina cellular communication
system in which a plurality of confiqurations that differ in
an uplink allocation and a downlink allocation of sub frames
10 in a radio frame are defined; and
a configuration switching step of switching
configurations between neighboring cells according to the
arrangement revised in the rearranging step when different
configurations are used in the neighboring cells in the
15 cellular communication system.
2. The wireless resource allocation method according to
claim 1,
wherein, in the rearranging step, an arrangement of at
20 least some configurations is revised to reduce the number of
sub frames in which an uplink and a downlink are mismatched
between adjacent configurations such that the plurality of
configurations are arranged preferentially in the ascending
order of the number of downlink sub frame rather than the
25 descending order of the number of uplink sub frames.
3. The wireless resource allocation method according to
claim 1,
wherein, in the rearranging step, an arrangement of at
30 least some configurations is revised to reduce the number of
sub frames in which an uplink and a downlink are mismatched
between adjacent configurations such that the plurality of
configurations are arrangedpreferentiallyinthe descending
order of the number of uplink sub frame rather than the ascending
order of the number of downlink sub frames.
5
4. The wireless resource allocation method according to
claim 1, further comprising,
a n e w c o n f i q u r a t i o n i n s e r t i n ~ s t e p o f i n s e r t i n ~ a n e w l ~
defined configuration between adjacent configurations in
10 which the number of sub frames in which the uplink and the
downlink are mismatched still increases in the arrangement
revised in the rearranging step,
wherein, in the configuration switching step,
configurations are switched between the neighboring cells
15 according to an arrangement in which the newly defined
configuration is inserted.
5 . The wireless resource allocation method according to
claim 4,
wherein, in the new configuration inserting step, a
configuration is newly defined such that sub frames in which
the uplink and the downlink are mismatched between the adjacent
configurations are dispersed into sub frames in which the
uplink and the downlink are mismatched between the
corresponding configuration and each of the adjacent
configurations.
6. The wireless resource allocation method according to
claim 1, further comprising,
30 an interference avoiding step of avoidinginterference
between the neighboring cells in sub frames in which the uplink
andthe downlinkaremismatchedbetweentheneighboringcells
whose configurations are switched i n the configuration
switching step.
5 7. The wireless resource allocation method according t o
claim 6,
wherein, in the inte-rference avoiding step, i n sub frames
i n which the uplink and the downlink are mismatched between
the neighboring c e l l s , transmission from a base s t a t i o n and
10 reception i n a terminal i n a c e l l allocated for the downlink
are stopped.
8. The wireless resource allocation method according t o
claim 6,
15 wherein, in the interference avoiding step, i n sub frames
i n which the uplink and the downlink are mismatched between
the neighboring c e l l s , transmission from a terminal and
reception i n a b a s e s t a t i o n i n a c e l l allocated f o r t h e uplink
arestopped, ortransmissionfromabasestationandreception
20 i n a t e r m i n a l i n a cellallocatedforthedownlinkare stopped
so t h a t sub frames whose transmission is stopped are not
concentrated i n some configurations.
9. The wireless resource allocation method according t o
25 claim 6,
wherein,intheinterferenceavoidingstep,insubframes
i n which the uplink and the downlink are mismatched between
the neighboring c e l l s , transmission from a terminal and
reception i n a b a s e s t a t i o n i n a c e l l allocated f o r t h e uplink
30 arestopped, or transmission fromabase stationandreception
i n a t e r m i n a l i n a c e l l allocated f o r t h e downlinkare stopped
SP33196OWOOO
according to concentration of traffic of each cell.
10. The wireless resource allocation method according to
claim 6,
5 wherein, in the interference avoiding step, in sub frames
in which a certain cell interferes with both adjacent cells
using different configurations, transmission and reception
in a base station and a terminal in the correspondinq cell
are stopped.
10
11. A wireless resource allocation device, comprising:
a rearranging unit that revises a configuration
arrangement of a plurality of configurations in view of an
increase in the number of downlink sub frames or a decrease
15 inthenumberofuplinksubframesinacellularcommunication
system in which a plurality of configurations that differ in
an uplink allocation and a downlink allocation of sub frames
in a radio frame are defined; and
a configuration switching unit that switches
20 configurations between neighboring cells according to the
arrangement revised in the rearranging step when different
configurations are used in the neighboring cells in the
cellular communication system.
25 12. A communication system that is configured to revise a
configuration arrangement of a plurality of configurations
in which an uplink allocation and a downlink allocation of
sub frames ina radio frame are definedinview of an increase
in the number of downlink sub frames and a decrease in the
30 numberofuplinksubframes, andswitchconfigurationsbetween
neighboring cells according to the revised arrangement when
L '-
diffe;ent configurations are used in the neighboring cells.
Dated this 2211 112013
ATTORNEY