Description
Title of Invention
COMMUNICATION CONTROL APPARATUS, COMMUNICATION CONTROL
5 METHOD, PROGRAM, COMMUNICATION SYSTEM, AND WIRELESS
TERMINAL
Technical Field
[0001]
10 The present invention relates to a communication control apparatus, a
communication control method, a program, a communication system, and a wireless
terminal.
Background Art
15 [0002]
Currently in 3GPP (Third Generation Partnership Project), standardization
of a 4G wireless communication system (cellular system) is under way. In such a
wireless communication system, it is important to improve communication capacity
at a cell edge. Thus, CoMP (Coordinated Multi-Point) is under discussion as a
20 means for improving communication capacity at a cell edge.
[0003]
CoMP is a method of performing communication with user terminals in
which a plurality of base stations cooperatively controls transmission/reception
parameters, scheduling, or beam/antenna directivity. Effects such as stabilization of
25 communication quality and increased communication capacities are expected from
CoMP
[0004]
In a wireless communication system, it is also important to efficiently
support communication traffic that arises locally. From the above perspective, the
30 introduction of HetNet (Heterogeneous Network) is also under discussion. HetNet
is a network in which large and small cells are arranged like being overlaid.
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According to HetNet, communication capacities in the whole area can be improved
by communication traflTic that arises locally, which has been hard to be covered by a
large cell like a macro sell, being covered by a small cell. As base stations forming
each cell, eNodeB, an RRH (Remote RadioHead) cell base station, a hot zone base
5 station (Pico/micro cell eNB), a femto cell base station (Home eNB), and a relay
apparatus (relay base station) can be assumed.
[0005]
These base stations can roughly be divided into CSG (Closed Subscriber
Group) cells that have access restrictions of user terminals and OSG (Open
10 Subscriber Group) that have no access restrictions. For example, a femto cell base
station is considered for operation as a CSG cell in the home and a preset user
terminal can access the femto cell base station. Technology in consideration of
such a CSG cell is disclosed by, for example. Patent Literature 1 and Patent
Literature 2.
15
Citation List
Patent Literature
[0006]
Patent Literature 1: JP 2011-501525W
20 Patent Literature 2: JP2010-213273A
Summary of Invention
Technical Problem
[0007]
25 As described above, the introduction of CoMP and the CSG cell are
expected in the future. However, no procedure of the CSG cell for cooperating with
other base stations is currently under discussion. Therefore, realizing a combination
of the CSG cell and CoMP has been difficult.
[0008]
30 Therefore, the present disclosure proposes a novel and improved
communication control apparatus to obtain a combined effect of the introduction of a
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communication control apparatus like a CSG cell that distinguishes between an
operation to some wireless terminal and an operation to another wireless terminal
and the introduction of cooperative communication like CoMP, a communication
control method, a program, a communication system, and a wireless terminal.
5
Solution to Problem
[0009]
According to the present disclosure, there is provided a communication
control apparatus including a communication controller that controls cooperative
10 communication linked to other communication control apparatuses depending on
whether the communication control apparatus or the other communication control
apparatuses perform terminal grouping to distinguish an operation to a specific
wireless terminal and to other wireless terminals.
[0010]
15 According to the present disclosure, there is provided a communication
control method, in which a communication control apparatus controls cooperative
communication linked to other communication control apparatuses depending on
whether the communication control apparatus or the other communication control
apparatuses perform terminal grouping to distinguish an operation to a specific
20 wireless terminal and to other wireless terminals.
[0011]
According to the present disclosure, there is provided a program causing a
computer to function as a communication control apparatus including a
communication controller that controls cooperative communication linked to other
25 communication control apparatuses depending on whether the communication
control apparatus or the other communication control apparatuses perform terminal
grouping to distinguish operations to a specific wireless terminal and to other
wireless terminals.
[0012]
30 According to the present disclosure, there is provided a communication
system including a first communication control apparatus, and a second
•
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communication control apparatus. The first communication control apparatus
includes a communication controller that controls cooperative communication linked
to the second communication control apparatus depending on whether the first
communication control apparatus or the second communication control apparatus
5 performs terminal grouping to distinguish operations to a specific wireless terminal
and to other wjreless terminals.
[0013]
According to the present disclosure, there is provided a wireless terminal
which communicates with a communication control apparatus that controls
10 cooperative communication that is communication with the communication control
apparatus, the cooperative communication being linked to other communication
control apparatuses depending on whether the communication control apparatus or
the other communication control apparatuses perform terminal grouping to
distinguish operations to a specific wireless terminal and to other wireless terminals.
15
Advantageous Effects of Invention
[0014]
According to the present disclosure, as described above, a communication
control apparatus to obtain a combined effect of the introduction of a communication
20 control apparatus like a CSG cell that distinguishes between an operation to some
wireless terminal and an operation to another wireless terminal and the introduction
of cooperative communication like CoMP, a communication control method, a
program, and a communication system are provided.
25 Brief Description of Drawings
[0015]
[FIG. 1] FIG. 1 is an explanatory view showing a configuration example of a wireless
communication system according to an embodiment of the present disclosure.
[FIG. 2] FIG. 2 is an explanatory view showing an example of permitting access of
30 only specific UE by grouping.
[FIG. 3] FIG. 3 is an explanatory view showing an example of a protocol related to
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access to a base station that groups UE.
[FIG. 4] FIG. 4 is an explanatory view showing another example of the protocol
related to access to the base station that groups UE.
[FIG. 5] FIG. 5 is an explanatory view showing the allocation of resources by the
5 base station that groups.
[FIG. 6] FIG. 6 is an explanatory view showing an example of cooperative
transmission to obtain a spatial diversity effect by two base stations.
[FIG. 7] FIG. 7 is an explanatory view showing an example of cooperative
transmission to obtain a spatial multiplexing effect by two base stations.
10 [FIG. 8] FIG 8 is an explanatory view showing an example of cooperative reception
to obtain the spatial diversity effect by two base stations.
[FIG. 9] FIG. 9 is an explanatory view showing an example of cooperative scheduling
in a frequency direction by two base stations.
[FIG. 10] FIG. 10 is an explanatory view showing an example of cooperative
15 scheduling in a time direction by two base stations.
[FIG 11] FIG. 11 is a functional block diagram showing the configuration of the base
station according to a first embodiment.
[FIG. 12] FIG. 12 is a sequence diagram showing an overview of operation of the
base station according to the present embodiment.
20 [FIG. 13] FIG. 13 is a sequence diagram showing a first communication example of
information about grouping.
[FIG. 14] FIG. 14 is a sequence diagram showing the first communication example of
information about grouping.
[FIG 15] FIG. 15 is a sequence diagram showing a second communication example
25 of information about grouping.
[FIG. 16] FIG. 16 is a sequence diagram showing the second communication example
of information about grouping.
[FIG. 17] FIG. 17 is a sequence diagram showing a third communication example of
information about grouping.
30 [FIG. 18] FIG. 18 is a sequence diagram showing the third communication example
of information about grouping.
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[FIG. 19] FIG 19 is a sequence diagram showing a fourth communication example of
information about grouping.
[FIG. 20] FIG. 20 is a sequence diagram showing the fourth communication example
of information about grouping.
5 [FIG. 21] FIG. 21 is a sequence diagram showing a fifth communication example of
information about grouping.
[FIG 22] FIG 22 is a sequence diagram showing the fifth communication example of
information about grouping.
[FIG. 23] FIG 23 is a flow chart showing a first judgment example about CoMP.
10 [FIG. 24] FIG 24 is a flow chart showing a second judgment example about CoMP.
[FIG 25] FIG 25 is a flow chart showing a third judgment example about CoMP.
[FIG. 26] FIG. 26 is a flow chart showing a fourth judgment example about CoMP.
[FIG. 27] FIG. 27 is a sequence diagram showing signaling to implement CoMP.
[FIG. 28] FIG. 28 is a sequence diagram showing signaling to implement CoMP.
15 [FIG. 29] FIG. 29 is an explanatory view showing a use case according to a second
embodiment.
[FIG. 30] FIG. 30 is a functional block diagram showing the configuration of the base
station according to the second embodiment.
[FIG 31] FIG. 31 is a flow chart showing a first operation example of the base station
20 according to the second embodiment.
[FIG. 32] FIG. 32 is a flow chart showing a second operation example of the base
station according to the second embodiment.
[FIG. 33] FIG. 33 is a flow chart showing a third operation example of the base
station according to the second embodiment.
25 [FIG. 34] FIG. 34 is a flow chart showing a fourth operation example of the base
station according to the second embodiment.
[FIG. 35] FIG. 35 is a functional block diagram showing the configuration of a
management node.
[FIG. 36] FIG 36 is a flow chart showing a first operation example of the
30 management node.
[FIG. 37] FIG. 37 is a flow chart showing a second operation example of the
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management node.
[FIG. 38] FIG 38 is a flow chart showing update processing of a terminal list by the
base station.
[FIG. 39] FIG. 39 is a sequence diagram showing the update processing of the
5 terminal list by the base station from another viewpoint.
[FIG. 40] FIG 40 is a sequence diagram showing the update processing of the
terminal list by the management node.
Description of Embodiments
10 [0016]
Hereinafter, preferred embodiments of the present disclosure will be
described in detail with reference to the appended drawings. Note that, in this
specification and the appended drawings, structural elements that have substantially
the same ftinction and structure are denoted with the same reference numerals, and
15 repeated explanation of these structural elements is omitted. In this specification
and the appended drawings, structural elements that have substantially the same
function and structure may be distinguished by attaching different alphabets after the
same reference numerals. For example, a plurality of configurations that have
substantially the same function and structure may be distinguished like UE 20A, UE
20 20B, UE 20C when necessary. However, when there is no need to specifically
distinguish each of a plurality of structural elements, only the same reference
numeral is attached. For example, if there is no need to specifically distinguish UE
20A, UE 20B, and UE 20C, UE 20A, UE 20B, and UE 20C are simply called UE 20.
[0017]
25 The present disclosure will be described in the order of items shown below:
1. Basic Configuration of Wireless Communication System
1-1. Grouping of UE
(Grouping for access restrictions)
(Grouping for priority connection)
30 1-2. CoMP
(Cooperative transmission)
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(Cooperative reception)
(Cooperative scheduling)
2. First Embodiment
2-1. Configuration of Base Station
5 2-2. Operation of Base Station
—Communication of information about grouping—
(First communication example: FIGS. 13, 14)
(Second communication example: FIGS. 15, 16)
(Third communication example: FIGS. 17, 18)
10 (Fourth communication example: FIGS. 19, 20)
(Fifth communication example: FIGS. 21, 22)
—Judgment whether to implement CoMP-
(First judgment example: FIG. 23)
(Second judgment example: FIG. 24)
15 (Third judgment example: FIG. 25)
(Fourth judgment example: FIG. 26)
—Procedure for performing CoMP—
3. Second Embodiment
3-1. Use Case of Second Embodiment
20 3-2. Configuration and Operation of Base Station
3-3. Configuration and Operation of Management Node
3-4. Supplementary Remarks - •
4. Summary
[0018]
25 «1. Basic Configuration of Wireless Communication System»
First, a basic configuration of a wireless communication system according
to an embodiment of the present disclosure will be described with reference to FIG. 1.
FIG. 1 is an explanatory view showing a configuration example of a wireless
communication system according to an embodiment of the present disclosure. As
30 shown in FIG. 1, a wireless communication system according to an embodiment of
the present disclosure includes eNodeB 11, a relay node 12, a femto cell base station
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13, UE (User Equipment) 20, and a management node 30.
[0019]
The eTStodeB 11 controls communication between the relay node 12 and the
UE 20 present inside a macro cell formed by the eNodeB 11. For example, eNodeB
5 llA manages scheduling information to communicate with UE 20A present in the
macro cell and communicates with the UE 20A according to the scheduling
information. Also, the eNodeB 11A manages scheduling information to
communicate with the relay node 12 present in the macro cell and manages
scheduling information for the relay node 12 and the UE 20B to communicate.
10 [0020]
Each of the eNodeB 11 is mutually connected via a wire communication
line called an X2 interface. Each of the eNodeB 11 is also connected to a
management node 30A via a wire communication line called an SI interface. Each
of the eNodeB 11 can communicate with other eNodeB or the management node 30
15 using these interfaces.
[0021]
The relay node 12 relays communication between the eNodeB 11 and the
UE 20 according to scheduling information managed by the eNodeB 11. More
specifically, the relay node 12 receives a signal transmitted from the eNodeB 11 in a
20 down link and transmits an amplified signal to the UE 20 using the frequency-time
according to scheduling information. By performing such a relay, when compared
with a case when a signal is directly transmitted from the eNodeB 11 to the UE 20
near a cell edge, the relay node 12 can make the signal-to-noise ratio larger.
[0022]
25 The femto cell base station 13 is a base station whose maximum
transmission power is smaller than that of the eNodeB 11 and forms a cell smaller
than a macro cell. The femto cell base station 13 is assumed to be arranged in the
home or office and forms, for example, CSG (Closed Subscriber Group) accessible
only from the UE 20 of the user in the home.
30 [0023]
The femto cell base station 13 is connected to a management node 30B and
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can communicate with the eNodeB 11 via a packet exchange network like ADSL.
Incidentally, the femto cell base station 13 may communicate with the eNodeB 11 via
a wireless link.
[0024]
5 The management node 30A is connected to each of the eNodeB 11 via a
backbone network. The management node 30A may also have a function as MME
(Mobile Management Entity) or a function as Serving Gateway. . The management
node 30A receives management information indicating the state of a macro cell
formed by each of the eNodeB 11 from each of the eNodeB 11 and controls.
10 communication in the macro cell formed by each of the eNodeB 11 based on the
management information. Incidentally, the function of the management node 30A
may be implemented by being distributed over a plurality of physically separated
configurations. Similarly, the management node 30B is connected to the femto cell
base station 13 and manages communication by the femto cell base station 13.
15 [0025]
The UE 20 is, as described above, a wireless terminal that communicates
with base stations like the eNodeB 11, the relay node 12, and the femto cell base
station 13. Data transmitted/received by the UE 20 includes audio data, music data
such as music, lectures, and radio programs, still image data such as photos,
20 documents, pictures, and diagrams, and dynamic image data such as video, TV
programs, video programs, and game images. FIG. 1 shows an example in which
the UE 20 is a smartphone, but the UE 20 may be any information processingapparatus
including a wireless communication function like a mobile phone, PC
(Personal Computer), mobile music reproducing apparatus, mobile game machine,
25 home music reproducing apparatus, and home game machine.
[0026]
According to a wireless communication system in an embodiment of the
present disclosure, as described above, a network called HetNet in which large and
small cells are arranged by being overlaid on each other. According to HetNet,
30 communication capacities in the whole area can be improved by communication
traffic that arises locally, which has been hard to be covered by a large cell like a
0
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macro sell, being covered by a small cell.
[0027]
Hereinafter, communication control apparatuses like the eNodeB 11, the
relay node 12, and the femto cell base station 13 forming HetNet may generically be
5 called base stations 10 when necessary. However, the base station 10 is not limited
to the eNodeB 11, the relay node 12, and the femto cell base station 13. For
example, the base station 10 may be a hot zone base station or RRH (Remote
RadioHead) cell base station.
[0028]
10 The hot zone base station is a base station whose maximum transmission
power is smaller than that of the eNodeB 11. The hot zone base station
communicates with the eNodeB 11 by using an interface like X2 or SI of the
backbone network. The hot zone base station forms OSG (Open Subscriber Group)
accessible from any of the UE 20.
15 [0029]
The RRH cell base station is connected to the eNodeB 11 via an optical fiber.
Thus, the eNodeB 11 can transmit a signal to the RRH cell base station arranged in a
geographically different location via an optical fiber to cause the RRH cell base
station to wirelessly transmit the signal. For example, only an RRH cell base
20 station close to the location of the UE 20 may be used. A control system function is
implemented in the eNodeB 11 and the eNodeB 11 selects the optimum transmission
form in accordance with the distribution of the UE 20.
[0030]
<1-1. Grouping of UE>
25 The eNodeB 11 described above is open to all the UE 20 and permits
connection from all the UE 20. With a macro cell being expanded areawide by the
eNodeB 11 described above, the UE 20 can communicate in a wide range.
[0031]
On the other hand, a base station like the femto cell base station 13 that
30 groups the UE 20 and permits access only from the specific UE 20. Such a base
station is called a CSG (Closed Subscriber Group) cell. For example, by adding the
p
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UE 20 of an employee of an office in which a CSG cell is installed or of a member of
the family to the CSG list, only the UE 20 contained in the CSG list can access the
CSG cell. With the introduction of the CSG cell, the CSG cell is expected to realize
high-quality and high-speed communication by preventing congestion of access by
5 the UE 20.
[0032]
The base station 10 can also give priority to the specific UE 20 for
connection over the other UE 20 by grouping of the UE 20. Accordingly, when
building a communication system, the allocation of communication resources to each
10 time/location can be made efficient to improve communication quality of a specific
user or a specific area. An example of permitting access of only the specific UE 20
by grouping and an example of allowing priority connection of the specific UE 20 by
grouping will be concretely described.
[0033]
15 (Grouping for access restrictions)
FIG. 2 is an explanatory view showing an example of permitting access of
only specific UE by grouping. A case in which, as shown in FIG. 2, a base station
lOA does not group the UE 20 and base stations lOB, IOC group the UE 20. The
base stations lOB, IOC have terminal lists showing the UE 20 pennitted to access
20 and the terminal list of the base station lOB contains the UE 20A, UE 20B, UE 20C
and the terminal list of the base station IOC contains the UE 20A, UE 20D, UE 20E.
[0034]
In this case, the base station lOA can communicate with any of the UE 20A,
UE 20B, UE 20D. On the other hand, the base station lOB can communicate with
25 the UE 20A, UE 20B, but cannot communicate with the UE 20D because the UE
20D is not contained in the terminal list. Similarly, the base station IOC can
communicate with the UE 20A, UE 20D, but cannot communicate with the UE 20B
because the UE 20B is not contained in the terminal list.
[0035]
30 FIG. 3 is an explanatory view showing an example of a protocol related to
access to the base station 10 that groups the UE 20. As shown in FIG. 3, when the
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UE 20 makes an inquiry about the terminal list at the base station 10 to make sure
whether the base station 10 is connectable (S52), the base station 10 checks whether
the UE 20 is contained in the terminal list (S54). Then, the base station 10 notifies
the UE 20 of the check result (S56) or takes action according to grouping of the UE
5 20 for the UE 20.
[0036]
FIG 4 is an explanatory view showing another example of the protocol
related to access to the base station that groups UE 20. An example in which the
base station 10 holds a terminal list is described in FIG. 3, but as shown in FIG 4, the
10 management node 30 may hold a terminal list or both of the base station 10 and the
management node 30 may hold a terminal list.
[0037]
More specifically, when the UE 20 makes an inquiry about the terminal list
at the base station 10 to make sure whether the base station 10 is connectable (S60),
15 the base station 10 transfers the inquiry to the management node 30 (S62). Then,
the management node 30 checks whether the UE 20 is contained in the terminal list
(S64) and transmits the check result to the base station 10 (S66). The base station
10 transfers the check result received from the management node 30 to the UE 20
(S68).
20 [0038]
Though an illustration is omitted in FIG 4, a physical node may further be
present between the base station 10 and the management node. In this case, an
interposing physical node plays the role of transferring an inquiry or a check result.
[0039]
25 (Grouping for priority connection)
By grouping the UE 20, as described above, priority connection of the
specific UE 20 can be realized. For example, the base station 10 can realize priority
connection by allocating more communication resources (such as the time, frequency,
code, and space) to the specific UE 20 than to other UE. This point will be
30 described more concretely below with reference to FIG 5.
[0040]
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FIG. 5 is an explanatory view showing the allocation of resources by the
base station 10 that groups UE. The base station 10 shown in FIG. 5 groups the UE
20 into the UE 20 contained in a list 1, the UE 20 contained in a list 2, and the other
UE 20 and provides communication resources for each group.
5 [0041]
In the example shown in FIG. 5, the base station 10 provides frequencies Fl
to F4 to the group of the UE 20 contained in the list 2, frequencies F5 to F7 to the
group of the UE 20 contained in the list 1, and a frequency F8 to the other UE 20.
Thus, the highest priority is given to the UE 20 contained in the list 2, the next
10 highest priority is given to the UE 20 contained in the list 1, and the lowest priority is
given to the other UE 20.
[0042]
FIG 5 shows an example in which communication resources in the
frequency direction are changed for each group, but other communication resources
15 in the time direction can also be changed for each group. Thus, with a plurality of
terminal lists held by the base station 10, finer communication content in a cell
formed by the base station 10 can be controlled.
[0043]

20 Subsequently, CoMP communication performed by the base station 10
according to an embodiment of the present disclosure will be described. The CoMP
communication is cooperative communication in which a- plurality of the base
stations 10 is coordinated to perform communication with the UE 20. Examples of
the CoMP communication include cooperative transmission, cooperative reception,
25 and cooperative scheduling. Each type of the CoMP communication will be
described below more concretely.
[0044]
(Cooperative transmission)
Cooperative transmission is a method of transmitting information intended
30 for the target UE 20 from a plurality of the base stations 10 to the target UE 20. In
this case, the plurality of base stations 10 uses the same communication resources
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(such as the frequency, time, space, and code) at least partially. In addition, the
plurality of base stations 10 adjusts transmission parameters such as the error
correcting method of information to be transmitted, error correction coding rate,
modulation method, and weighting between the base stations 10. Accordingly, an
5 effect of the spatial transmission diversity by the plurality of base stations 10
(improvement of reception quality) or an effect of spatial multiplexing by different
information being transmitted by the plurality of base stations 10 using the same
communication resources (improvement of transmission rate) can be expected.
[0045]
10 FIG 6 is an explanatory view showing an example of cooperative
transmission to obtain a spatial diversity effect by the two base stations 10. When
cooperative transmission is performed to obtain a spatial diversity effect, as shown in
FIG. 6, the base stations lOA, lOB transmit the same information to the UE 20A
using the same frequency and time resources, but different spatial resources. More
15 specifically, the base station lOA uses a spatial weight Wl and the base station lOB
uses a spatial weight W2 to transmit the same information Dl. The spatial weights
Wl, W2 are desirably selected so that a combined signal can obtain a diversity effect
when signals are received by the UE 20A. The base stations lOA, lOB may use a
communication network like a packet exchange network as shown in FIG. 1 or a wire
20 channel to select resources and to share and control the same information between
the base stations 10.
[0046]
FIG. 7 is an explanatory view showing an example of cooperative
transmission to obtain a spatial multiplexing effect by the two base stations 10.
25 When cooperative transmission is performed to obtain a spatial multiplexing effect,
as shown in FIG. 7, the base stations lOA, lOB transmit different information to the
UE 20A using the same frequency and time resources, but different spatial resources.
The base stations lOA, lOB may use, like the example shown in FIG. 6, a
communication network like a packet exchange network or a wire channel to select
30 resources and to share and control information transmitted from the respective base
station between the base stations 10.
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[0047]
According to the cooperative transmission by the two base stations 10, as
described above, when compared with a case when information is transmitted to the
UE 20A by the base station 10 alone, higher transmission rate (for example, a double
5 transmission rate) can be obtained.
[0048]
(Cooperative reception)
Cooperative reception is a method of decoding information by a signal
transmitted from the target UE 20 being received by a plurality of the base stations
10 10 and the received signal being exchanged between the plurality of base stations 10
or the received signal being gathered at a predetermined place. In this case, the
plurality of base stations 10 allocates the same communication resources (such as the
frequency, time, space, and code) at least partially to the UE 20. Accordingly, an
effect of spatial reception diversity by the plurality of base stations 10 is obtained
15 and thus, for example, reception quality of an up link of the communication system
can be improved.
[0049]
FIG. 8 is an explanatory view showing an example of cooperative reception
to obtain the spatial diversity effect by the two base stations 10. When cooperative
20 reception is performed to obtain a spatial diversity effect, as shown in FIG. 8, the
base stations lOA, lOB allocate the same frequency and time resources to the UE
20A and theUE 20A uses allocated resources to transmit a signal. The base stations
lOA, lOB attempt to decode information by transferring respective received signals
to a predetermined location or exchanging received signals between the base station
25 1 OA and the base station lOB. Thus, by using received signals of a plurality of the
base stations 10 to decode information, reception quality can be improved.
Incidentally, information may be decoded by an apparatus other than the base station
lOA and the base station lOB. The UE 20A may transmit information by using
spatial weights.
30 [0050]
(Cooperative scheduling)
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Cooperative scheduling is a method of adjusting the allocation of resources
such that allocated resources to the UE 20 by each of a plurality of the base stations
10 performing communication with the target UE 20 are at least partially different.
Accordingly, signals from the plurality of base stations 10 are orthogonal in at least a
5 portion of communication resources and thus, the reduction of interference on the
side of the UE 20 can be expected.
[0051]
FIG. 9 is an explanatory view showing an example of cooperative
scheduling in a frequency direction by the two base stations 10. When cooperative
10 scheduling in the frequency direction is performed, as shown in FIG. 9, the base
stations IDA, lOB transmit different information using the same time resources, but
different frequency resources. Accordingly, signals from the base station lOA and
the base station lOB are orthogonal in the UE 20A and thus, interference can be
reduced.
15 [0052]
FIG. 10 is an explanatory view showing an example of cooperative
scheduling in a time direction by the two base stations 10. When cooperative
scheduling in the time direction is performed, as shown in FIG. 10, the base stations
10A, lOB transmit different information using the same frequency resources, but
20 different time resources. Also with the above configuration, signals from the base
station lOA and the base station lOB are orthogonal in the UE 20A and thus,
interference can be reduced.
[0053]
FIGS. 9 and 10 show examples in which different information is transmitted
25 from the base stations lOA, lOB, but the base stations lOA, lOB can obtain a
diversity effect by transmitting the same information. FIGS. 9 and 10 shows
transmission from a plurality of the base stations 10 to the UE 20, but cooperative
scheduling for transmission from the UE 20 to the plurality of base stations 10 can
also be realized by a similar method.
30 [0054]
(Supplementary remarks about CoMP)
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As described above, cooperative control of communication resources used
and sharing (distribution) of transmission information are needed for CoMP, but the
main agent that realizes cooperative control and sharing of transmission information
is not particularly limited. For example, the main agent may be the base station 10
5 (serving base station) to which the target UE 20 is connected or another apparatus
like the management node 30 shown in FIG. 1.
[0055]
« 2 . First Embodiment»
In the foregoing, the basic configuration of a wireless communication
10 system according to the present disclosure has been described with reference to FIGS.
1 to 10. Subsequently, the first embodiment of the present disclosure will be
described. As will be described in detail below, the base station 10 according to the
first embodiment of the present disclosure performs communication of infomiation
about grouping of the UE 20 with surrounding base stations to be able to control
15 CoMP communication based on the infonnation about grouping.
[0056]
<2-l. Configuration of Base Station>
FIG. 11 is a functional block diagram showing the configuration of the base
station 10 according to the first embodiment. As shown in FIG 11, the base station
20 10 according to the first embodiment includes a wireless communication unit 110, a
wire communication unit 120, a storage unit 130, and a communication controller
140.
[0057]
The wireless communication unit 110 functions as a transmitting unit to
25 transmit a wireless signal to the UE 20 and as a receiving unit to receive a wireless
signal from the UE 20. For example, the wireless communication unit 110 may be
configured for reception and contain a plurality of antennas, an analog processing
unit, an AD converter, a digital processing unit, and a decoder. The wireless
communication unit 110 may be configured for transmission and contain an encoder,
30 a digital processing unit, a DA converter, an analog processing unit, and a plurality of
antennas.
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[0058]
The wire communication unit 120 functions as a transmitting unit to
transmit information to the other base station 10, the management node 30 or the like
and as a receiving unit to receive information from the other base station 10, the
5 management node 30 or the like. The base station 10 according to the present
embodiment can communicate, as will be described in detail in "2-2. Operation of
Base Station", information about grouping and information to implement CoMP via
the wire communication unit 120. FIG. 11 shows an example of wire interface to
the other base station 10 or the management node 30, but the interface to the other
10 base station 10 or the management node 30 may be wireless.
[0059]
The storage unit 130 is a storage medium that stores programs to operate the
base station 10 and various kinds of information. Particularly when the base station
10 groups the UE 20, a terminal list showing content of the grouping is stored in the
15 storage unit 130.
[0060]
The communication controller 140 controls overall communication of the
base station 10 such as communication with the UE 20 by the wireless
communication unit 110 and communication with the other base stations 10 by the
20 wire communication unit 120. More specifically, the communication controller 140
controls communication of information about grouping with the other base station 10.
The communication controller 140 also sets communication parameters to perform
CoMP communication with the other base station 10. If terminal list is stored in the
storage unit 130, the communication controller. 140 determines whether to allow
25 communication with the UE 20 in accordance with whether the target UE 20 is
contained in the terminal list or gives priority to connection of the target UE 20.
[0061]
<2-2. Operation of Base Station>
In the foregoing, the configuration of the base station 10 according to the
30 present embodiment has been described with reference to FIG. 11. Subsequently,
after providing an overview of the operation of the base station 10 according to the
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present embodiment with reference to FIG. 12, the operation of the base station 10
according to the present embodiment will be described in detail.
[0062]
FIG. 12 is a sequence diagram showing an overview of the operation of the
5 base station 10 according to the present embodiment. As shown in FIG 12, the
base stations lOA, lOB transmit information about grouping of the UE 20 (S600).
The information about grouping may be, as will be described in "Communication of
information about grouping" in detail, information about whether or not the UE 20 is
grouped or information whether a terminal list having the specific UE 20 is held.
10 [0063]
Then, the base station lOA determines whether to implement CoMP with the
base station lOB based on the information about grouping obtained in the
communication in S600 (S700). Then, if the base station lOA determines to
implement CoMP, the base station lOA proceeds to the procedure to implement
15 CoMP with the base station lOB (S800). O the other hand, if the base station lOA
determines not to implement CoMP, the base station lOA performs communication
by a different method like one-to-one communication with the UE 20 (S860).
[0064]
Therefore, according to the present embodiment, a combined effect of the
20 introduction of grouping of the UE 20 and the introduction of CoMP can be obtained.
Each operation by the base station 10 according to the present embodiment described
above will be described in detail below. Two base- stations (lOA and lOB) are
shown as an example of a plurality of base station in FIG. 12, but the present
embodiment can also be applied to communication by the three base stations 10 or
25 more.
[0065]
—Communication of information about grouping—
Whether each of the base stations 10 groups the UE 20 is very important to
judge whether to implement CoMP. Thus, as shown in S600 in FIG. 12, the base
30 station 10 checks whether the surrounding base stations 10 group the UE 20.
Hereinafter, a communication protocol of information about grouping between the
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base stations 10 will be described, but another apparatus may be interposed between
the base stations 10. In such a case, the interposed apparatus plays the role of
signaling or transferring ACK/NACK. When information about grouping is
managed by an apparatus (for example, the management node 30) other than the base
5 station 10, the communication protocol described below may be invoked as the
communication protocol between the base station 10 and the management node 30.
[0066]
(First communication example: FIGS. 13, 14)
FIGS. 13 and 14 are sequence diagrams showing a first communication
10 example of information about grouping. In the first communication example, as
shown in FIG. 13, the base station lOA notifies the base station lOB of having
grouped the UE 20 (S602). In addition to having grouped the UE 20, the base
station lOA may make a notification of a terminal list held by the base station lOA.
When the notification is received from the base station lOA, the base station lOB
15 transmits ACK to the base station 1OA (S604).
[0067]
On the other hand, if the base station lOB fails to receive the notification
from the base station lOA, as shown in FIG. 14, the base station lOB transmits
NACK to the base station lOA (S606). Alternatively, the base station lOB transmits
20 neither ACK nor NACK to the base station lOA (no response). In this case, the
base station lOA may notify the base station lOB of having grouped the UE 20 again
(S608). In addition, a predetermined upper limit may be set to the number of times
of notification. When the number of times of notification reaches the
predetermined upper limit, retransmission of the notification may be stopped.
25 [0068]
(Second communication example: FIGS. 15, 16)
FIGS. 15 and 16 are sequence diagrams showing a second communication
example of information about grouping. In the second communication example, as
shov/n in FIG. 15, the base station lOA makes an inquiry about whether the base
30 station lOB groups the UE 20 at the base station lOB (S612). When the inquiry is
received from the base station lOA, the base station lOB transmits information
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indicating whether the base station lOB groups the UE 20 to the base station lOA
(S614).
[0069]
On the other hand, when NACK is received from the base station lOB or no
5 response is received from the base station lOB (S616), as shown in FIG. 16, the base
station lOA may make an inquiry about whether the base station lOB groups the UE
20 at the base station lOB again (S618). In addition, a predetermined upper limit
may be set to the number of times of inquiry. When the number of times of inquiry
reaches the predetermined upper limit, retransmission of the inquiry may be stopped.
10 [0070]
(Third communication example: FIGS. 17, 18)
FIGS. 17 and 18 are sequence diagrams showing a third communication
example of information about grouping. In the third communication example, as
shown in FIG 17, the base station lOA makes an inquiry about the terminal list of the
15 base station lOB at the base station lOB (S622). When the inquiry is received from
the base station lOA, the base station lOB transmits the terminal list of the base
station lOB to the base station lOA (S624).
[0071]
On the other hand, when NACK is received from the base station lOB or no
20 response is received from the base station lOB (S626), as shown in FIG. 18, the base
station lOAmay make an inquiry about the terminal list of the base station lOB at the
base station lOB again (S628). In addition, a predetermined upper limit may be set
to the number of times of inquiry. When the number of times of inquiry reaches the
predetermined upper limit, retransmission of the inquiry may be stopped. After
25 making sure that the base station lOB groups the UE 20 according to the second
communication example, the base station lOA may exercise the control of the third
communication example.
[0072]
(Fourth communication example: FIGS. 19, 20)
30 FIGS. 19 and 20 are sequence diagrams showing a fourth communication
example of information about grouping. In the fourth communication example, as
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shown in FIG. 19, the base station IDA makes an inquiry about whether target UE
20X is contained in the terminal list of the base station lOB at the base station lOB
(S632). When the inquiry is received from the base station lOA, the base station
lOB checks whether the UE 20X is contained in the terminal list of the base station
5 1 OB and transmits the check result to the base station 1OA (S634).
[0073]
On the other hand, when NACK is received from the base station lOB or no
response is received from the base station lOB (S636), as shown in FIG. 20, the base
station lOA may make an inquiry about whether target UE 20X is contained in the
10 terminal list of the base station lOB at the base station lOB again (S638). In
addition, a predetermined upper limit may be set to the number of times of inquiry.
When the number of times of inquiry reaches the predetermined upper limit,
retransmission of the inquiry may be stopped. After making sure that the base
station lOB groups the UE 20 according to the second communication example, the
15 base station lOA may exercise the control of the fourth communication example.
[0074]
(Fifth communication example: FIGS. 21, 22)
FIGS. 21 and 22 are sequence diagrams showing a fifth communication
example of information about grouping. In the fifth communication example, as
20 shown in FIG. 21, the base station lOA makes an inquiry about whether to participate
in CoMP concerning the target UE 20X (S642). When the inquiry is received from
the-base station lOA, the base station lOB judges whether CoMP can be performed
for the UE 20X and transmits the result to the base station lOA (S644). If, for
example, the base station lOB does not group the UE 20, the UE 20X is contained in
25 the terminal list of the base station lOB, or the base station lOB is open to the UE
20X that is not contained in the terminal list, the base station lOB may determine that
CoMP for the UE 20X is possible.
[0075]
On the other hand, when NACK is received from the base station lOB or no
30 response is received from the base station lOB (S646). as shown in FIG. 22. the base
station lOA may make an inquiry about whether to participate in CoMP concerning
t
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the target UE 20X at the base station lOB again (S648). In addition, a
predetermined upper limit may be set to the number of times of inquiry. When the
number of times of inquiry reaches the predetermined upper limit, retransmission of
the inquiry may be stopped. After making sure that the base station lOB groups the
5 UE 20 according to the second communication example, the base station lOA may
exercise the control of the fifth communication example. Further, after making sure
that the base station lOB groups the UE 20 according to the third communication
example or the fourth communication example, the base station lOA may exercise
the control of the fifth communication example.
10 [0076]
(Supplementary remarks about communication of information about
grouping)
The communication protocol of information about grouping described
above is desirably implemented particularly in the application layer. With the
15 above configuration, any protocol can be selected in a lower layer of the channel
actually connecting the base stations 10 or the management nodes 30 and therefore,
the degree of freedom of the configuration of a communication system can be
improved. Particularly when the above communication protocol is implemented in
a cellular system like LTE (Long Term Evolution), the above communication
20 protocol is desirably implemented as a portion of the X2 interface or the SI interface.
In this manner, the cost of newly implementing a protocol interface can be reduced.
[0077]
-Judgment whether to implement CoMP—
As described above, after communicating information about grouping of the
25 UE 20 with surrounding base stations, the base station 10 can judge whether to
implement CoMP and if CoMP should be performed, in which way to implement
CoMP. Concrete examples of such judgment will be described below. The
judgment about CoMP may be made by the base station 10 (serving base station) to
which the UE 20 intended for CoMP is mainly connected or by the other base station
30 10 or the management node 30.
[0078]
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(First judgment example: FIG 23)
FIG 23 is a flow chart showing a first judgment example about CoMP. As
shown in FIG. 23, the communication controller 140 of the base station 10 first
checks information about grouping received from surrounding base stations (S702).
5 Then, if the base station 10 does not group the UE 20 (S704) and a surrounding base
station groups the UE 20 (S706), the communication controller 140 controls one-toone
communication with the target UE 20 (S708).
[0079]
On the other hand, if the base station 10 groups the UE 20 (S704) or no
10 surrounding base station groups the UE 20 (S706), the communication controller 140
controls communication with the UE 20 by any method like CoMP (S710).
[0080]
According to the first judgment, if at least one base station that groups the
UE 20 is present in the surrounding, the base station 10 performs normal one-to-one
15 communication with the target UE. Accordingly, simple communication with the
UE 20 can be realized by suppressing signaling to implement CoMP.
[0081]
(Second judgment example: FIG 24)
FIG. 24 is a flow chart showing a second judgment example about CoMP.
20 As shown in FIG. 24, the communication controller 140 of the base station 10 first
checks information about grouping received from surrounding base stations (S712).
Then, if the base stafion 10 groups the UE 20 (S714), the communication controller
140 controls communication with the UE 20 by any method like one-to-one
communication, broadcast communication, or CoMP communication (S716).
25 [0082]
On the other hand, if the base station 10 does not group the UE 20 (S714),
the communication controller 140 repeats the processing in S718 to S724 for each
surrounding base station. More specifically, if a surrounding base station groups
the UE 20 (S718), th"" target UE 20 is not contained in the terminal list of the
30 surrounding base station (S720), and the surrounding base station is not open to the
UE 20 that is not contained in the terminal list (S722), the communication controller
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140 excludes the surrounding base station from partners of CoMP (S724).
[0083]
Then, the communication controller 140 controls communication to request
cooperation of CoMP with surrounding base stations that are not excluded from
5 partners of CoMP (S726).
[0084]
(Third judgment example: FIG. 25)
FIG 25 is a flow chart showing a third judgment example about CoMP. As
shown in FIG 25, the communication controller 140 of the base station 10 first
10 checks information about grouping received from surrounding base stations (S732).
Then, if the base station 10 groups the UE 20 (S734), the communication controller
140 controls one-to-one communication with the UE 20 (S736). On the other hand,
if the base station 10 does not group the UE 20 (S734), the communication controller
140 controls communication with the UE 20 by any method like one-to-one
15 communication, broadcast communication, or CoMP communication (S738).
[0085]
According to the third judgment example, if the base station 10 is a CSG
cell like, for example, a femto cell base station, the base station 10 judges not to
implement CoMP. In this case, signaling to implement CoMP can be reduced.
20 When operating according to the third judgment example, the base station 10 may
not have the step (S600) of performing communication about grouping with
surrounding base stations as described with reference to FIGS. 12 to 22.
[0086]
(Fourth judgment example: FIG. 26)
25 FIG. 26 is a flow chart showing a fourth judgment example about CoMP.
As shown in FIG 26, the communication controller 140 of the base station 10 first
checks information about grouping received from surrounding base stations (S742).
Then, if the base station 10 does not group the UE 20 (S744), the communication
controller 140 controls communication with the UE 20 by any method like one-to-
30 one communication or CoMP communication (S746).
[0087]
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On the other hand, if the base station 10 groups the UE 20 (S744), the
communication controller 140 repeats the processing in S748 to S754 for each
surrounding base station. More specifically, if a surrounding base station groups
the UE 20 (S748), the target UE 20 is not contained in the terminal list of the
5 surrounding base station (S750), and the surrounding base station is not open to the
UE 20 that is not contained in the terminal list (S752), the communication controller
140 excludes the surrounding base station from partners of CoMP (S754).
[0088]
Then, the communication controller 140 controls communication to request
10 cooperation of CoMP with surrounding base stations that are not excluded from
partners of CoMP (S756).
[0089]
(Supplementary remarks about judgment whether to implement CoMP)
To sum up judgment examples described above, the base station 10 operates
15 as described below. For convenience of description, a base station that does not
group the UE 20 is called an OSG cell and a base station that groups the UE 20 is
called a CSG cell.
[0090]
A. When the serving base station is an OSG cell
20 A-1. When a CSG cell is present in the surrounding
A-1-1. When an OSG cell is present in the surrounding
(Operation example 1) CoMP with the surrounding base station including
the CSG cell
(Operation example 2) CoMP with the base station excluding the CSG cell
25 in the surrounding
(Operation example 3) CoMP is not performed
A-1-2. When an OSG cell is not present in the surrounding
(Operation example 1) CoMP with the CSG cell
(Operation example 2) CoMP is not performed
30 A-2. When a CSG cell is not present in the surrounding
A-2-1. When an OSG cell is present in the surrounding
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(Operation example) CoMP with the OSG cell
A-2-2. When an OSG cell is not present in the surrounding
(Operation example) CoMP is not performed
[0091]
5 B. When the serving base station is a CSG cell
B-1. When a CSG cell is present in the surrounding
B-1-1. When an OSG cell is present in the surrounding
(Operation example 1) CoMP with the surrounding base station including
the OSG cell
10 (Operation example 2) CoMP with the base station excluding the OSG cell
in the surrounding
(Operation example 3) CoMP is not performed
B-1-2. When an OSG cell is not present in the surrounding
(Operation example 1) CoMP with the base station excluding the OSG cell
15 in the surrounding
(Operation example 2) CoMP is not performed
B-2. When a CSG cell is not present in the surrounding
B-2-1. When an OSG cell is present in the surrounding
(Operation example 1) CoMP with the surrounding base station including
20 the OSG cell
(Operation example 2) CoMP is not performed
B-2-2. When an OSG cell is not present in the surrounding
(Operation example) CoMP is not performed
[0092]
25 —Procedure for performing CoMP—
When a judgment to implement CoMP is made by the above method, the
base station 10 performs signaling to implement CoMP. A concrete example will be
described below with reference to FIGS. 27 and 28.
[0093]
30 FIGS. 27 and 28 are sequence diagrams showing signaling to implement
CoMP. When, as shown in FIG. 27, information indicating participation in CoMP is
»
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received from the base station lOB, the base station lOA selects or calculates
communication resource to implement CoMP and transmission/reception parameters
such as the spatial weight, modulation method, and coding method (S802). Then,
the base station lOA notifies the base station lOB of selection results such as
5 transmission/reception parameters (S804). Subsequently, when ACK is received
from the base station lOB (S806), the base station lOA implements CoMP according
to communication resources and transmission/reception parameters selected in S802
(S808). A concrete example of CoMP is as shown in "1-2. CoMP".
[0094]
10 On the other hand, when NACK is received from the base station lOB or no
response is received from the base station lOB (S810), as shown in FIG. 28, the base
station lOA notifies the base station lOB of selection results such as
transmission/reception parameters (S812). In addition, a predetermined upper limit
may be set to the number of times of notification. When NACK is received from
15 the base station lOB or no response is received from the base station lOB (S810), or
the number of times of notification reaches the predetermined number of times, the
base station lOA may perform one-to-one communication with the UE 20 without
implementing CoMP or implement CoMP with surrounding base stations.
[0095]
20 Each of the base stations 10 may perform the following processing when
implementing CoMP.
(a)
The serving base station 10 notifies the other base stations 10 that
implement CoMP of the terminal ID of the target UE 20 and information to be
25 transmitted. Each of the base stations 10 having received the notification transmits
the notified information to the UE 20 having the notified terminal ID.
(b)
The serving base station 10 notifies the other base stations 10 that
implement CoMP of the terminal ID of the target UE 20 and scheduling information.
30 Each of the base stations 10 having received the notification allocates
communication resources (the slot and resource block) indicated by the notified
9
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scheduling information for the UE 20 having the notified terminal ID.
(c)
The serving base station 10 notifies the other base stations 10 that
implement CoMP of the terminal ID of the target UE 20 and scheduling information.
5 Each of the base stations 10 having received the notification allocates different
communication resources from communication resources indicated by the notified
scheduling information for the UE 20 having the notified terminal ID.
(d)
A plurality of the base stations 10 that implement CoMP changes at least
10 one parameter of transmission power, antenna directivity, and antenna weights from
parameters during past transmission when transmitting a signal to the UE 20. These
parameters may be decided by each of the base stations 10. In such a case, each of
the base stations 10 may use past reception results of signals transmitted from the UE
20 to set these parameters. These parameters may also be decided by the serving
15 base station 10 or the UE 20.
(e)
At least a portion of the plurality of base stations 10 that implement CoMP
other than the serving base station 10 decodes and demodulates a signal when the
signal is received from the target UE 20 and transmits the result to the serving base
20 station 10.
(f)
At least a portion of the plurality of base stations 10 that implement CoMP
other than the serving base station 10 does not transmit ACK/NACK from the UE 20
to the serving base station 10. Further, the plurality of base stations 10 that
25 implement CoMP does not have to decode and demodulate ACK/NACK and does
not have to schedule ACK/NACK.
(g)
At least a portion of the plurality of base stations 10 that implement CoMP
does not transmit ACK/NACK to data received from the UE 20.
30 (h)
At least a portion of the plurality of base stations 10 that implement CoMP
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transmits a signal to the target UE 20 or receives a signal from the UE 20 using the
same frequency band or frequency bands having an overlapping portion.
[0096]
According to the first embodiment of the present disclosure, as described
5 above, CoMP communication can appropriately be controlled even in a network in
which the base station 10 that group the UE 20 like CSG cells and OSG cells and the
base station 10 that does not group the UE 20 are mixed. That is, advantages due to
the introduction of the base station 10 that groups the UE 20 and the introduction of
CoMP communication can be obtained at the same time.
10 [0097]
« 3 . Second Embodiment»
Subsequently, the second embodiment of the present disclosure will be
described. In the second embodiment of the present disclosure, a mechanism to
allow a plurality of base stations 10' to share the same terminal list will be proposed.
15 [0098]
<3-l. Use Case of Second Embodiment>
In the second embodiment, a use case in which the plurality of base stations
10' having the same terminal list constitutes a communication system is assumed.
For example, in a relatively large office, a use case in which the whole office is
20 covered by the plurality of base stations 10' (small base stations like femto cell base
stations) can be considered.
[0099]
In the example shown in FIG. 29, base stations lO'A to lO'D are arranged in
the same office and the base stations lO'A to lO'D have the same terminal list.
25 Accordingly, the UE 20 contained in the terminal list can connect to any of the base
stations 10' from anywhere in the office. Incidentally, the terminal list may be
managed by a management node 30'. In addition, the base station 10' can perform
one-to-one communication with the UE 20 or, as described in the first embodiment,
implement CoMP.
30 [0100]
In such a communication system, it is important that the same terminal list
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is shared by each of the base stations 10'. Thus, the configuration to allow each of
the base stations 10' to share the same terminal list will be described in detail.
[0101]
<3-2. Configuration and Operation of Base Station>
5 FIG 30 is a functional block diagram showing the configuration of the base
station 10' according to the second embodiment. As shown in FIG 30, the base
station 10' according to the second embodiment include the wireless communication
unit 110, the wire communication unit 120, the storage unit 130, a communication
controller 142, a list comparison unit 150, and a list update unit 160. The wireless
10 communication unit 110, the wire communication unit 120, and the storage unit 130
are as described in the first embodiment and thus, a detailed description thereof is
here omitted.
[0102]
The communication controller 142 controls, in addition to the function of
15 the communication controller 140 described in the first embodiment, communication
to acquire the terminal lists of the surrounding base stations 10'. The
communication controller 142 also controls communication to request an update of
the terminal lists of the surrounding base stations 10'.
[0103]
20 The list comparison unit 150 compares the terminal lists of the surrounding
base stations 10' and the terminal list of the base station 10' stored in the storage unit
130 to determine whether there is the surrounding base station 10' whose terminal list
is different from the terminal list of the base station 10'.
[0104]
25 When the list comparison unit 150 determines that there is the surrounding
base station 10' whose terminal list is different from the terminal list of the base
station 10', for example, the list update unit 160 matches the terminal list of the base
station 10' stored in the storage unit 130 to the terminal list of the surrounding base
stafion 10'.
30 [0105]
Also when the list comparison unit 150 determines that there is the
9
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surrounding base station 10' whose terminal list is different from the terminal list of
the base station 10', the communication controller 142 may control communication
that requests matching of the terminal list of the surrounding base stations 10' to the
terminal list of the base station 10' stored in the storage unit 130.
5 [0106]
Hereinafter, operation examples of the base station 10' will concretely be
described with reference to FIGS. 31 to 34.
[0107]
(First operation example)
10 FIG. 31 is a flow chart showing a first operation example of the base station
10' according to the second embodiment. As shown in FIG. 31, first when the base
station 10' acquires the terminal lists of the surrounding base stations 10' according to
the control of the communication controller 142 (S902), the list comparison unit 150
determines whether there is the surrounding base station 10' whose terminal list is
15 different from the terminal list of the base station 10' stored in the storage unit 130
(S904).
[0108]
Then, if there is the surrounding base station 10' having a different terminal
list from the terminal list of the base station 10' and the UE 20 that is not contained in
20 the terminal list of the base station 10' is contained in the terminal list of the
surrounding base station 10', the list update unit 160 adds the applicable UE 20 to the
terminal list of the base station 10' (S908). Then, the base station 10' proceeds to
the step of communication with the UE 20 (S910).
[0109]
25 (Second operation example)
FIG. 32 is a flow chart showing a second operation example of the base
station 10' according to the second embodiment. As shown in FIG. 32, first when
the base station 10' acquires the terminal lists of the surrounding base stations 10'
according to the control of the communication control 142 (S912), the list
30 comparison unit 150 determines whether there is the surrounding base station 10'
whose terminal list is different from the terminal list of the base station 10' stored in
0
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the storage unit 130 (S914).
[0110]
Then, if there is the surrounding base station 10' having a different terminal
list from the terminal list of the base station 10' and the UE 20 that is not contained in
5 the terminal list of the surrounding base station 10' is contained in the terminal list of
the base station 10' (S916), the list update unit 160 deletes the applicable UE 20 from
the terminal list of the base station 10' (S918). Then, the base station 10' proceeds
to the step of communication with the UE 20 (S920).
[0111]
10 The terminal lists of the base station 10' and the surrounding base station 10'
can be matched by the first operation example and the second operation example
described above. Examples in which the terminal list of the base station 10' is
updated are described above, but like a third operation example and a fourth
operation example described below, the terminal lists of the base station 10' and the
15 surrounding base station 10' can also be matched by updating the terminal list of the
surrounding base station 10'.
[0112]
(Third operation example)
FIG. 33 is a flow chart showing a third operation example of the base station
20 10' according to the second embodiment. As shown in FIG. 33, first when the base
station 10' acquires the terminal lists of the surrounding base stations 10' according to
the control of the communication control 142 (S922), the list comparison unit 150
determines whether there is the surrounding base station 10' whose terminal list is
different from the terminal list of the base station 10' stored in the storage unit 130
25 (S924).
[0113]
Then, if there is the surrounding base station 10' having a different terminal
list from the terminal list of the base station 10' and the UE 20 that is not contained in
the terminal list of the base station 10' is contained in the terminal list of the
30 surrounding base station 10' (S926). the communication controller 142 controls
communication that requests deletion of the applicable UE 20 from the surrounding
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base station 10' (S928). Then, the base station 10' proceeds to the step of
communication with the UE 20 (S930).
[0114]
(Fourth operation example)
5 FIG. 34 is a flow chart showing a fourth operation example of the base
station 10' according to the second embodiment. As shown in FIG. 34, first when
the base station 10' acquires the terminal lists of the surrounding base stations 10'
according to the control of the communication controller 142 (S932), the list
comparison unit 150 determines whether there is the surrounding base station 10'
10 whose terminal list is different from the terminal list of the base station 10' stored in
the storage unit 130 (S934).
[0115]
Then, if there is the surrounding base station 10' having a different terminal
list from the terminal list of the base station 10' and the UE 20 that is not contained in
15 the terminal list of the surrounding base station 10' is contained in the terminal list of
the base station 10' (S936), the communication controller 142 controls
communication that requests addition of the applicable UE 20 from the surrounding
base station 10' (S938). Then, the base station 10' proceeds to the step of
communication with the UE 20 (S940).
20 [0116]
<3-3. Configuration and Operation of Management Node>
Examples of matching the terminal lists of the plurality of base station 10'
by the base station 10' acting as a main agent are described above, but the
management node 30' may also act as a main agent to match the terminal lists of the
25 plurality of base station 10'. The configuration and operation of the above
management node 30' will be described in detail below.
[0117]
FIG. 35 is a functional block diagram showing the configuration of the
management node 30'. As shown in FIG. 35, the management node 30' includes a
30 wire communication unit 320, a communication controller 342. a list comparison unit
350, and a list creation unit 370.
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[0118]
The wire communication unit 320 functions as a transmitting unit to
transmit information to the base station 10' and as a receiving unit to receive
information from the base station 10'. For example, the wire communication unit
5 320 receives the terminal list from each of the base stations 10' and transmits the
terminal list created by the list creation unit 370 to each of the base stations 10'.
FIG. 35 shows an example in which a wire interface is formed between the
management node 30' and the base station 10', but a wireless interface may be
formed between the management node 30' and the base station 10'.
10 [0119]
The communication controller 342 controls the overall communication by
the wire communication unit 320. For example, the communication controller 342
controls communication to request the terminal list from each of the base stations 10'
or transmission of the terminal list created by the list creation unit 370 to each of the
15 base stations 10'.
[0120]
The list comparison unit 350 compares the terminal lists received by the
wire communication unit 320 from the base stations 10' to determine whether, among
the terminal lists of the base stations 10', there is a terminal list that is different from
20 others.
[0121]
If it is determined that, among the terminal lists of the base stations 10',
there is a terminal list that is different from others, the list creation unit 370 creates a
new list based on the tenninal list of each of the base stations 10'. The new terminal
25 list created by the list creation unit 370 is transmitted to each of the base stations 10'
from the wire communication unit 230.
[0122]
An operation example of the management node 30' will be described more
concretely below with reference to FIGS. 36 and 37.
30 [0123]
FIG. 36 is a flow chart showing a first operation example of the
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management node 30'. As shown in FIG. 36, when the management node 30'
receives the terminal list from each of the base stations 10' under the control of the
communication controller 342 (S952), the list comparison unit 350 determines
whether, among the terminal lists of the base stations 10', there is a terminal list that
5 is different from others (S954).
[0124]
Subsequently, if there is a terminal list that is different from others, the list
creation unit 370 newly creates a terminal list containing the UE 20 included in one
of these terminal lists of the base stations 10' (S956). If, for example, the terminal
10 list of the base station lO'A contains the UE 20A, UE 20B, UE 20D and the terminal
list of the base station lO'B contains the UE 20A, UE 20B, UE 20C, the list creation
unit 370 creates a terminal list containing the UE 20A, UE 20B, UE 20C. UE 20D.
Then, the wire communication unit 320 transmits the new terminal list created by the
list creation unit 370 to each of the base stations 10' (S958).
15 [0125]
FIG. 37 is a flow chart showing a second operation example of the
management node 30'. As shown in FIG 37, when the management node 30'
receives the terminal list from each of the base stations 10' under the control of the
communication controller 342 (S962), the list comparison unit 350 determines
20 whether, among the terminal lists of the base stations 10', there is a terminal list that
is different from others (S964).
[0126]
Subsequently, if there is a terminal list that is different from others, the list
creation unit 370 newly creates a terminal list containing the UE 20 included in all
25 terminal lists of the base stations 10' (S966). If, for example, the terminal list of the
base station lO'A contains the UE 20A, UE 20B, UE 20D and the terminal list of the
base station lO'B contains the UE 20A, UE 20B, UE 20C, the list creation unit 370
creates a terminal list containing the UE 20A, UE 20B. Then, the wire
communication unit 320 transmits the new terminal list created by the list creation
30 unit 370 to each of the base stations 10' (S968).
[0127]
D
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In the second operation example, the UE 20 excluding the UE 20 permitted
to access all the base stations 10' is excluded and thus, from the viewpoint of security,
the example is robust with respect to access from the UE 20.
[0128]
5 <3-4. Supplementary Remarks>
In the foregoing, examples of updating the terminal list by the base station
10' or the management node 30' as a main agent have been described. The terminal
list may periodically be updated by the base station 10' or the management node 30',
but as will be described below, the base station 10' or the management node 30' may
10 update the terminal list in accordance with a request from the UE 20.
[0129]
FIG. 38 is a flow chart showing update processing of the terminal list by the
base station 10'. As shown in FIG 38, when a request of addition/deletion of the
UE 20 to/from the terminal list is received from the UE 20 (S970), the wireless
15 communication unit 110 of the base station 10' adds the UE 20 to the terminal list of
the storage unit 130 or deletes the UE 20 from the terminal list (S972).
[0130]
Then, the wire communication unit 120 of the base station 10' transmits the
terminal list updated by the list update unit 160 to the surrounding base stations 10'
20 (S974). Then, when a response to the terminal list is received from the surrounding
base stations 10', the base station 10' completes the update processing by notifying
the UE 20 of the update completion (S976). On the other hand, if an update
notification is not received by the wire communication unit 120 from the surrounding
base station 10', the wire communication unit 120 retransmits the updated terminal
25 list to the surrounding base stations 10' (S974).
[0131]
FIG. 39 is a sequence diagram showing the update processing of the
terminal list by the base station 10' from another viewpoint. As shown in FIG. 39,
when the UE 20 requests the base station 10'A to add/delete the UE 20 to/from the
30 terminal list (S981), the base station lO'A transmits the request to the other base
station lO'B (S982). FIG. 39 shows only the two base stations 10', but when the
^
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more base stations 10' constitute a communication system, each of the base stations
10' may sequentially transfer the request, for example, in a relay form.
[0132]
Then, each of the base stations 10' having received the request to add/delete
5 the UE 20 to/from the terminal list updates the terminal list according to the request
(S983, S984). Then, each of the base stations 10' transmits an update notification
indicating that the terminal list is updated (S985, S986).
[0133]
An example in which each of the base stations 10' individually updates the
10 terminal list is described above, but as will be described with reference to FIG 40,
one apparatus such as the management node 30' may update the terminal list.
[0134]
FIG. 40 is a sequence diagram showing the update processing of the
terminal list by the management node 30'. As shown in FIG 40, when the UE 20
15 requests the base station lO'A to add/delete the UE 20 to/from the terminal list (S991),
the base station lO'A transmits the request to the management node 30' (S992) and
then, the management node 30' updates the terminal list according to the request
(S993) and transmits the updated terminal list to each of the base stations (S994,
S995). Then, base station lO'A transmits an update notification indicating that the
20 terminal list is updated to the UE 20 (S996).
[0135]
As described abovCj the base station lO'A or the management node 30' may
update the terminal list in accordance with, for example, a request from the UE 20 or
update the terminal list in accordance with a request from outside the communication
25 system or a human operation on the base station 10'A or the management node 30'.
[0136]
« 4 . Summary»
According to the present disclosure, even if the UE 20 is grouped and many
base stations like CSG cells that distinguish an operation to the UE 20 belonging to
30 each group are introduced, CoMP including such base stations can be implemented
and therefore, a combined effect of the introduction of CSG cells and the
^
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introduction of CoMP can be obtained. As a result, communication capacities in
the whole area can be improved while efficiently covering communication traffic that
arises locally and therefore, user experience can be improved.
[0137]
5 Although preferred embodiments of the present disclosure have been
described in detail with reference to the appended drawings, the technical scope of
the present disclosure is by no means limited to these examples. A person skilled in
the art finds various alterations and modifications within the scope of the appended
claims, and it should be understood that they will naturally come under the technical
10 scope of the present invention.
[0138]
For example, each step of processing by the base station 10, the
management node 30 and the like in this specification does not necessarily need to be
executed chronologically in the order described as a sequence diagram or flow chart.
15 For example, each step of processing by the base station 10, the management node
30 and the like may be executed in an order that is different from the order described
as a flow chart or in parallel.
[0139]
A computer program that causes hardware such as a CPU, ROM, and RAM
20 contained in the base station 10, the management node 30 and the like to fiinction on
a par with each configuration of the base station 10, the management node 30 and the
like can be created. In addition, a storage medium in which the computer program
is stored is provided.
[0140]
25 Additionally, the present technology may also be configured as below.
(1)
A communication control apparatus including:
a communication controller that controls cooperative communication linked
to other communication control apparatuses depending on whether the
30 communication control apparatus or the other communication control apparatuses
perform terminal grouping to distinguish operations to a specific wireless terminal
9
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and to other wireless terminals.
(2)
The communication control apparatus according to (1), wherein, when the
communication control apparatus and another first communication control apparatus
5 do not perform the terminal grouping and another second communication control
apparatus performs the terminal grouping, the communication controller controls the
cooperative communication linked to the other first communication control apparatus.
(3)
The communication control apparatus according to (1) or (2), wherein,
10 when another second communication control apparatus has a terminal list containing
a target wireless terminal as the specific wireless terminal, the communication
controller controls the cooperative communication linked to the other second
communication control apparatus.
(4)
15 The communication control apparatus according to any one of (1) to (3),
wherein, when another second communication control apparatus permits connection
to the other wireless terminals, the communication controller controls the cooperative
communication linked to the other second communication control apparatus.
(5)
20 The communication control apparatus according to any one of (1) to (4),
wherein, when the communication control apparatus performs terminal grouping, the
communication controller controls one-to-one communication with a target wireless
terminal.
(6)
25 The communication control apparatus according to any one of (1) to (5),
wherein the communication controller controls communication with the other
communication control apparatuses, the communication exchanging information
about the terminal grouping.
(7)
30 The communication control apparatus according to (6). wherein the
communication controller controls communication of inquiry about whether the other
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communication control apparatuses perform the terminal grouping.
(8)
The communication control apparatus according to (6) or (7), wherein the
communication controller controls communication of inquiry about a terminal list
5 showing the terminal grouping in the other communication control apparatuses.
(9)
The communication control apparatus according to any one of (6) to (8),
wherein the communication controller controls communication of inquiry about
whether the other communication control apparatuses have a terminal list containing
10 a target wireless terminal as the specific wireless terminal.
(10)
The communication control apparatus according to any one of (6) to (9),
wherein the communication controller controls communication of inquiry about
whether it is possible to participate in the cooperative communication linked to the
15 other communication control apparatuses to communicate with a target wireless
terminal.
(11)
The communication control apparatus according to any one of (1) to (10),
wherein the specific terminal is one of a terminal permitted to connect to the
20 communication control apparatus and a terminal preferentially connected to the
communication control apparatus.
(12) • - .:: .. •
A communication control method, wherein a communication control
apparatus controls cooperative communication linked to other communication
25 control apparatuses depending on whether the communication control apparatus or
the other communication control apparatuses perform terminal grouping to
distinguish operations to a specific wireless terminal and to other wireless terminals.
(13)
A program causing a computer to function as
30 a communication control apparatus including
a communication controller that controls cooperative
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communication linked to other communication control apparatuses depending on
whether the communication control apparatus or the other communication control
apparatuses perform tenninal grouping to distinguish operations to a specific
wireless terminal and to other wireless terminals.
5 (14)
A communication system including:
a first communication control apparatus; and
a second communication control apparatus,
wherein the first communication control apparatus includes a
10 communication controller that controls cooperative communication linked to the
second communication control apparatus depending on whether the first
communication control apparatus or the second communication control apparatus
performs terminal grouping to disfinguish operations to a specific wireless terminal
and to other wireless terminals.
15 (15)
A wireless terminal which communicates with a communication control
apparatus that controls cooperative communication that is communication with the
communication control apparatus, the cooperative communication being linked to
other communication control apparatuses depending on whether the communication
20 control apparatus or the other communication control apparatuses perform terminal
grouping to distinguish operations to a specific wireless terminal and to other
wireless terminals. . ,-,
Reference Signs List
25 [0141]
10 base station
20 UE
30 management node
110 wireless communication unit
30 120, 320wire communication unit
130 storage unit
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140, 142, 342 communication controller
150, 3501ist comparison unit
160 list update unit
170 list creation unit

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CLAIMS
Claim 1
A communication control apparatus comprising:
a communication controller that controls cooperative communication linked
5 to other communication control apparatuses depending on whether the
communication control apparatus or the other communication control apparatuses
perform terminal grouping to distinguish operations to a specific wireless terminal
and to other wireless terminals.
10 Claim 2
The communication control apparatus according to claim 1, wherein, when
the communication control apparatus and another first communication control
apparatus do not perform the terminal grouping and another second communication
control apparatus perforais the terminal grouping, the communication controller
15 controls the cooperative communication linked to the other first communication
control apparatus.
Claim 3
The communication control apparatus according to claim 1, wherein, when
20 another second communication control apparatus has a terminal list containing a
target wireless terminal as the specific wireless terminal, the communication
controller controls the cooperative communication linked to the other second
communication control apparatus.
25 Claim 4
The communication control apparatus according to claim 1, wherein, when
another second communication control apparatus permits connection to the other
wireless terminals, the communication controller controls the cooperative
communication linked to the other second communication control apparatus.
30
Claim 5
c; * * . - * • '
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The communication control apparatus according to claim 1, wherein, when
the communication control apparatus performs terminal grouping, the
communication controller controls one-to-one communication with a target wireless
terminal.
5
Claim 6
The communication control apparatus according to claim 1, wherein the
communication controller controls communication with the other communication
control apparatuses, the communication exchanging information about the terminal
10 grouping.
Claim 7
The communication control apparatus according to claim 6, wherein the
communication controller controls communication of inquiry about whether the other
15 communication control apparatuses perform the terminal grouping.
Claim 8
The communication control apparatus according to claim 6, wherein the
communication controller controls communication of inquiry about a terminal list
20 showing the terminal grouping in the other communication control apparatuses.
Claim 9
The communication control apparatus according to claim 6, wherein the
communication controller controls communication of inquiry about whether the other
25 communication control apparatuses have a terminal list containing a target wireless
terminal as the specific wireless terminal.
Claim 10
The communication control apparatus according to claim 6, wherein the
30 communication controller controls communication of inquiry about whether it is
possible to participate in the cooperative communication linked to the other
. *••> V fi • ^ I
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communication control apparatuses to communicate with a target wireless terminal.
Claim 11
The communication control apparatus according to claim 1, wherein the
5 specific terminal is one of a terminal permitted to connect to the communication
control apparatus and a terminal preferentially connected to the communication
control apparatus.
Claim 12
10 A communication control method, wherein a communication control
apparatus controls cooperative communication linked to other communication
control apparatuses depending on whether the communication control apparatus or
the other communication control apparatuses perform terminal grouping to
distinguish operations to a specific wireless terminal and to other wireless terminals.
15
Claim 13
A program causing a computer to function as
a communication control apparatus comprising
a communication controller that controls cooperative
20 communication linked to other communication control apparatuses depending on
whether the communication control apparatus or the other communication control
apparatuses perform terminal grouping to distinguish operations to a specific
wireless terminal and to other wireless terminals.
25 Claim 14
A communication system comprising:
a first communication control apparatus; and
a second communication control apparatus,
wherein the first communication control apparatus includes a
30 communication controller that controls cooperative communication linked to the
second communication control apparatus depending on whether the first
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communication control apparatus or the second communication control apparatus
performs terminal grouping to distinguish operations to a specific wireless terminal
and to other wireless terminals.
5 Claim 15
A wireless terminal which communicates with a communication control
apparatus that controls cooperative communication that is communication with the
communication control apparatus, the cooperative communication being linked to
other communication control apparatuses depending on whether the communication
10 control apparatus or the other communication control apparatuses perform terminal
grouping to distinguish operations to a specific wireless terminal and to other
wireless terminals.