1. A base station comprising: a storage unit; and a processing unit, wherein the storage unit stores a neighbour relation table, and the processing unit is configured to: receive service information of a neighbour cell to its own cell, the service information being transmitted by another base station forming the neighbour cell to the own cell, the service information including at least one of an information element indicating whether the another base station has a function of a wireless LAN (Local Area Network) base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity, and register the service information of the neighbour cell with the neighbour relation table.

2. The base station according to claim 1, wherein the processing unit transmits, into the own cell, the service information of the own cell.

3. The base station according to claim 2, wherein the processing unit broadcasts, in the own cell, the service information of the own cell, and receives, from a terminal in a connected state to the own cell, the service information of the neighbour cell received by the terminal from the neighbour cell.

4. The base station according to claim 2 or 3, wherein the processing unit determines a handover destination cell of a terminal that is in a connected state to the own cell, based on the service information of the neighbour cell registered with the neighbour relation table.

5. A wireless communication system comprising: a terminal; and a plurality of base stations, wherein each of the plurality of base stations is configured to: receive service information of a neighbour cell to its own cell, the service information being transmitted by another base station forming the neighbour cell to the own cell, the service information including at least one of an information element indicating whether the another base station has a function of a wireless LAN (Local Area Network) base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity, and register the service information of the neighbour cell with a neighbour relation table.

6. The wireless communication system according to claim 5, wherein each of the plurality of base stations broadcasts, within the own cell, the service information of the own cell, and receives, from a terminal that is in a connected state to the own cell, the service information of the neighbour cell received by the terminal from the neighbour cell.

7. The wireless communication system according to claim 5 or 6, wherein each of the plurality of base stations determines a handover destination cell of a terminal that is in a connected state to the own cell, based on the service information of the neighbour cell registered with the neighbour relation table.

8. A communication method for use in a base station, comprising: a reception step of receiving service information of a neighbour cell to its own cell, the service information being transmitted by another base station forming the neighbour cell to the own cell, the service information including at least one of an information element indicating whether the another base station has a function of a wireless LAN (Local Area Network) base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity; and a registration step of registering the service information of the neighbour cell with a neighbour relation table.

9. The communication method according to claim 8, further comprising a transmission step of broadcasting, within the own cell, the service information of the own cell, wherein the reception step comprises receiving, from a terminal that is in a connected state to the own cell, the service information of the neighbour 25 cell received by the terminal from the neighbour cell.

10. The communication method according to claim 8 or 9, further comprising a determination step of determining a handover destination cell of a terminal that is in a connected state to the own cell, based on the service information of the neighbour cell registered with the neighbour relation table.

Technical Field
[0001]
The present invention relates to a base station, a wireless communication system, and a communication method. Background Art [0002]
Firstly, independent three techniques relevant to the present invention are described.
(A) 3GPP TS (3rd Generation Partnership Project Technical Specification)
36.300 V12.1.0 (NPL 1) prescribes a function called Energy Saving. This
function refers to a function of, in an environment where an E-UTRAN
Node B (hereinafter, eNB) in an Evolved Universal Terrestrial Radio
Access Network (E-UTRAN) forms a cell providing basic coverage,
automatically switching the power on/off of an antenna by another base
station disposed within the coverage. For example, when large-volume
traffic occurs temporarily in a relatively narrow area within the coverage,
the antenna of the above-described base station is powered on to add a cell.
This enables dynamic addition of a communication capacity. In this
manner, a cell for switching the power on/off of an antenna is expected to
accommodate large-volume traffic that occurs temporarily in a relatively
narrow area. This cell is called as a "capacity booster cell" in 3GPP
25 TS36.300 V12.1.0 (NPL 1), and is called a "cell for dynamically adding a communication capacity" in the present Description.
(B) Operation where a UE uses radio resources provided by at least two
eNBs connected with non-ideal backhaul (e.g., X2 interface) is called
"dual connectivity." This is defined in 3GPP TR (3GPP Technical

Report) 36.842 V12.0.0 (NPL 2). A User Equipment (hereinafter,
referred to as a UE) communicates with a Master eNB (hereinafter,
referred to as an MeNB) in part of cells of a Master Cell Group (hereinafter,
referred to as an MCG) formed by the MeNB. In addition, the UE
communicates with a Secondary eNB (hereinafter, referred to as an SeNB)
in part of cells of a Secondary Cell Group (hereinafter, referred to as an
SCG) formed by the SeNB. Since the SeNB is an additional node, the
SCG is also additional.
(C) In order to support traffic increase, a telecommunications carrier
disposes an eNB that has both the function of a Long-Term Evolution
(LTE) base station, a 3rd-Generation (3G) base station, or a Global System
for Mobile Communication (GSM) base station and the function of a
wireless Local Area Network (LAN) base station. Then, the eNB
concurrently forms an LTE cell, a 3G cell, or a GSM cell and a wireless
LAN cell. With this configuration, the load on the network can be
reduced.
Citation List
Patent Literature
[0003]
PTL 1: Japanese Translation of PCT International Application Publication
No. JP-T-2013-502749
PTL 2: Japanese Unexamined Patent Application Publication No.
2013-172406
PTL 3: Japanese Unexamined Patent Application Publication No.
2013-250174
Non Patent Literature
[0004]
NPL 1: 3GPP TS36.300 V12.1.0
NPL 2: 3GPP TR36.842 V12.0.0

NPL 3: 3GPP TS25.484 Vll.1.0 NPL 4: 3GPP TS36.331 V12.1.0 NPL 5: 3GPP TS25.331 vl2.1.0 NPL 6: 3GPP TS36.413 V12.1.0 NPL 7: 3GPP TS36.306 V12.0.0 NPL 8: 3GPP TS37.320 V12.0.0 NPL 9: 3GPP TR37.822 VI.2.0 Summary of Invention Technical Problem [0005]
Automatic Neighbour Relation (hereinafter, ANR) prescribed in 3GPP TS36.300 V12.1.0 (NPL 1) refers to a function of enabling automatic execution of the following operation by a system without operator's management. Firstly, an eNB instructs a UE to collect and report system information broadcasted in each neighbour cell. The eNB then constructs a Neighbour Relation Table (hereinafter, referred to as an NRT) based on the report from the UE. A neighbour cell herein includes not only a peripheral cell adjacent to its own cell, but also a cell that is in an inclusion relation with the own cell (e.g., a cell of a macro base station and a cell of a femto base station or the like disposed in the cell are in an inclusion relation). The eNB then determines a cell appropriate as a handover destination or a reselection destination based on the NRT, and notifies the UE of the determined cell. A similar function in a UTRAN is prescribed in 3GPP TS25.484 Vll.1.0 (NPL 3). In 3GPP, the ANR is regarded as part of a Self-organizing network (hereinafter, SON) function. Note that PTLs 1 to 3 also disclose that a UE measures the communication quality of each neighbour cell and reports the measured communication quality to a network. [0006]

The ANR utilizes system information of a cell defined in 3GPP TS36.331 vl2.1.0 (NPL 4) and 3GPP TS25.331 vl2.1.0 (NPL 5). The UE measures the communication quality based on the received system information, and reports information such as the communication quality, a cell ID, and a Tracking area ID (TAI) to a network. [0007]
However, the system information defined in 3GPP TS36.331 V12.1.0 (NPL 4) and 3GPP TS25.331 vl2.1.0 (NPL 5) may alone be insufficient for an eNB to determine a handover destination cell of a UE in some cases. [0008]
Therefore, the objective of the present invention is to provide a base station, a wireless communication system, and a communication method that enable to solve the above-described problem. Solution to Problem [0009]
A base station of the present invention includes:
a storage unit; and
a processing unit, wherein
the storage unit stores a neighbour relation table, and
the processing unit receives service information of a neighbour cell that is transmitted by another base station forming the neighbour cell adjacent to its own cell and that includes at least one of an information element indicating whether the other base station has a function of a wireless LAN base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity, and registers the service information of the neighbour cell with the neighbour relation table. [0010]

A wireless communication system of the present invention includes:
a terminal; and
a plurality of base stations, wherein
each of the plurality of base stations receives service information of a neighbour cell that is transmitted by another base station forming the neighbour cell adjacent to a its own cell and that includes at least one of an information element indicating whether the other base station has a function of a wireless LAN base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity, and registers the service information of the neighbour cell with a neighbour relation table. [0011]
A communication method of the present invention is a communication method by a base station, and includes:
a reception step of receiving service information of a neighbour cell that is transmitted by another base station forming the neighbour cell adjacent to a its own cell and that includes at least one of an information element indicating whether the other base station has a function of a wireless LAN base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity; and
a registration step of registering the service information of the neighbour cell with a neighbour relation table. Advantageous Effects of Invention 25 [0012]
The present invention produces an advantageous effect that a base station is able to obtain sufficient information to determine a handover destination cell of a terminal. Brief Description of Drawings

[0013]
Fig. 1 is a diagram illustrating an example of the entire configuration of a wireless communication system according to the present exemplary embodiment.
Fig. 2 is a block diagram illustrating an example of the configuration of the eNB illustrated in Fig. 1.
Fig. 3 is a sequence diagram illustrating an example of a processing sequence during construction of an NRT in the wireless communication system according to the present exemplary embodiment.
Fig. 4 is a diagram illustrating an example of service information in the wireless communication system according to the present exemplary embodiment.
Fig. 5 is a sequence diagram illustrating an example of a processing sequence during handover in the wireless communication system according to the present exemplary embodiment.
Fig. 6 is a diagram illustrating an example of the arrangement of cells of the wireless communication system according to the present exemplary embodiment.
Fig. 7 is a diagram illustrating an example of the NRT in the wireless communication system according to the present exemplary embodiment.
Fig. 8 is a flowchart illustrating an example of a process flow during determination of a handover destination cell in the wireless communication system according to the present exemplary embodiment. 25 Description of Embodiments [0014]
The following describes an exemplary embodiment for carrying out the present invention with reference to the drawings. (1) Configuration of Exemplary Embodiment

(1-1) Entire Configuration of Wireless Communication System
Fig. 1 is a diagram illustrating the entire configuration of a wireless communication system according to the present exemplary embodiment. [0015]
As illustrated in Fig. 1, the wireless communication system according to the present exemplary embodiment includes an eNB 10-1, an eNB 10-2, a UE 20, and a mobility management entity (MME) 30. [0016]
The eNB 10-1 is a base station that forms an E-UTRAN cell 11-1. [0017]
The eNB 10-2 is a base station that forms an E-UTRAN cell 11-2. [0018]
The UE 20 is a terminal that communicates with the eNBs 10-1 and 10-2. [0019]
The MME 30 is a mobility management server that forms an Evolved Packet Core (hereinafter, referred to as an EPC). [0020]
Note that, hereinafter, the eNBs 10-1 and 10-2 are simply referred to as eNBs 10 in the case where they are not distinguished. [0021]
In addition, for the convenience of illustration, there are two eNBs 10 and one UE 20 illustrated in Fig. 1. However, eNBs 10 and UEs 20 other than the above may exist. 25 (1-2) Configuration of eNB 10
Fig. 2 is a block diagram illustrating an example of the configuration of the eNB 10-1 illustrated in Fig. 1. [0022]
As illustrated in Fig. 2, the eNB 10-1 includes a communication

unit 101, a storage unit 102, and a processing unit 103. [0023]
The communication unit 101 communicates with outside. [0024]
The storage unit 102 stores a neighbour relation table (NRT) or the like with which service information or the like of each neighbour cell adjacent to the E-UTRAN cell 11-1 is registered. [0025]
The processing unit 103 performs, for example, the following processing of:
•broadcasting service information of the E-UTRAN cell 11-1 within the E-UTRAN cell 11-1 via the communication unit 101; •receiving service information of each neighbour cell adjacent to the E-UTRAN cell 11-1 via the communication unit 101; •constructing an NRT;
•determining a handover destination cell of the UE 20 based on the NRT; and
•notifying the UE 20 of the handover destination cell via the communication unit 101.
Note that the configuration of the eNB 10-2 is the same as that of the eNB 10-1. (2) Operation of Present Exemplary Embodiment
The following describes the operation of the wireless communication system according to the present exemplary embodiment. (2-1) Operation of Constructing NRT
Firstly, the operation of constructing an NRT is described. [0026]
Fig. 3 is a sequence diagram illustrating an example of a processing sequence during construction of an NRT. Fig. 4 is a diagram illustrating

an example of service information. [0027]
The following describes Steps in Fig. 3. [0028]
Step Al:
The processing unit 103 of the eNB 10-2 broadcasts, within the E-UTRAN cell 11-2, service information of the E-UTRAN cell 11-2 as illustrated in Fig. 4, as being system information. In Fig. 4, underlined "capacity-booster-cell-Capable" and "wLAN-Capable" are newly added information elements. [0029]
"capacity-booster-cell-Capable" is an information element indicating whether the E-UTRAN cell 11-2 is a cell for dynamically adding a communication capacity. [0030]
"wLAN-Capable" is an information element indicating whether the eNB 10-2 forming the E-UTRAN cell 11-2 has a function of a wireless LAN base station. [0031]
Step A2:
The processing unit 103 of the eNB 10-1 transmits, to the UE 20, a
request to measure the communication quality of another cell in order to
make the UE 20 to report service information of the other cell.
[0032]
25 Step A3:
The UE 20 acquires the service information of the E-UTRAN cell 11-2 that is broadcasted within the E-UTRAN cell 11-2 by the eNB 10-2. [0033]
Step A4:

The UE 20 reports, to the eNB 10-1, a measurement result including the service information of the E-UTRAN cell 11-2. [0034]
Step A5:
The processing unit 103 of the eNB 10-1 adds the service information of the E-UTRAN cell 21 to an NRT. Accordingly, the NRT of the eNB 10-1 includes the E-UTRAN cell 21 added as being a neighbour cell. At this time, the value of "capacity-booster-cell-Capable" and the value of "wLAN-Capable" in the service information of the UTRAN cell 21 are set to corresponding attribute values. [0035]
Step A6:
The processing unit 103 of the eNB 10-1 newly adds the E-UTRAN cell 11-2 as being a candidate of a handover destination cell. In other words, the E-UTRAN cell 11-2 is a target for measurement of the communication quality in the next transmission of the measurement request. Consequently, the UE 20 that receives the measurement request for the next time acquires the service information of the E-UTRAN cell 11-2, and measures the communication quality of the E-UTRAN cell 11-2 based on the acquired service information. (2-2) Handover Operation
Next, the handover operation is described. [0036]
Fig. 5 is a sequence diagram illustrating an example of a processing 25 sequence during handover. [0037]
The following describes Steps in Fig. 5. [0038]
Step Bl:

The UE 20 is in a connected state to the E-UTRAN cell 11-1 (RRC CONNECTED state). [0039]
Step B2:
The processing unit 103 of the eNB 10-1 determines that the UE 20 needs to be handed over from the E-UTRAN cell 11-1 to another cell, based on the measurement result reported from the UE 20. [0040]
Step B3:
The processing unit 103 of the eNB 10-1 determines a handover destination cell of the UE 20 based on the service information of the neighbour cell registered with the NRT. [0041]
Step B4:
The processing unit 103 of the eNB 10-1 notifies the UE 20 of the handover destination cell. After the handover, the UE 20 continues communication in the handover destination cell. (2-3) Operation of Determining Handover Destination Cell
Next, a detailed description is made on the operation of determining a handover destination cell, which is carried out at Step B3 in Fig. 5. [0042]
Fig. 6 is a diagram illustrating an example of the arrangement of
cells of the wireless communication system.
[0043]
25 It is assumed that the arrangement of cells of the wireless
communication system according to the present exemplary embodiment is as illustrated in Fig. 6. In addition, it is assumed that the eNB 10-1 registers, with the NRT, E-UTRAN cells 11-3 to 11-5 in addition to the above-described E-UTRAN cell 11-2 as being neighbour cells at a point of

time when a handover trigger is generated at Step B2 in Fig. 5. An
example of the NRT at this time is illustrated in Fig. 7.
[0044]
Fig. 7 is a diagram illustrating an example of the NRT in the wireless communication system. [0045]
The value of "capacity-booster-cell-Capable" and the value of "wLAN-Capable" of each of the E-UTRAN cells 11-2 to 11-5 are as follows:
•E-UTRAN cell 11-2 (capacity-booster-cell-Capable=FALSE, wLAN-Capable=TRUE)
•E-UTRAN cell 11-3 (capacity-booster-cell-Capable=TRUE, wLAN-Capable=FALSE)
•E-UTRAN cell 11-4 (capacity-booster-cell-Capable=FALSE, wLAN-Capable=FALSE)
•E-UTRAN cell 11-5 (capacity-booster-cell-Capable=FALSE, wLAN-Capable=FALSE)
In addition, it is assumed that the E-UTRAN cell 11-5 is a cell of a macro base station. In addition, it is assumed that the E-UTRAN cells 11-1 to 11-4 are cells of a micro base station, a pico base station, or a femto base station having a cell diameter smaller than the cell of a macro base station and disposed for hot spot countermeasure. [0046]
The processing unit 103 of the eNB 10-1 compares the value of QCI 25 IE in E-RAB Level QoS Parameters and the values of UE Aggregate
Maximum Bit Rate Downlink IE and Aggregate Maximum Bit Rate Uplink IE in UE Aggregate Maximum Bit Rate, which are prescribed in 3GPP TS36.413 V12.1.0 (NPL 6), with the past statistical information. The processing unit 103 of the eNB 10-1 then estimates, based on a result of the

13 comparison, an amount of data transmitted and received by the UE 20 in
the past.
[0047]
Further, the processing unit 103 of the eNB 10-1 estimates, based
5 on the value of horizontalVelocity in Location Information element
prescribed in 3GPP TS36.331 V12.1.0 (NPL 4), a speed of movement of the
UE 20.
[0048]
The processing unit 103 of the eNB 10-1 performs handover control
10 whereby a handover destination cell of the UE 20 is determined based on
the NRT in consideration of subscriber information, such as an amount of
data transmitted and received by the UE 20 in the past, a speed of
movement of the UE 20, and the presence or absence of a function of a
wireless LAN terminal in the UE 20.
15 [0049]
Fig. 8 is a chart illustrating an example of a process flow indicating
a determination logic during determination of a handover destination cell.
However, the process flow is merely exemplary and it is assumed that
different determination logics may be implemented depending on the
20 policy of a telecommunications carrier and the policy for network design.
The following describes Steps in Fig. 8. [0050]
Step C1:
The processing unit 103 of the eNB 10-1 determines whether the UE
25 20 is moving at a low speed. For example, the processing unit 103
determines that the UE 20 is moving at a low speed when a speed of the
movement of the UE 20 is less than a threshold value.
[0051]
When the UE 20 is moving at a low speed, the processing proceeds

14 to Step C2.
[0052]
On the other hand, when the UE 20 is not moving at a low speed
(moving at a high speed), the processing proceeds to Step C7.
5 [0053]
Step C2:
The processing unit 103 of the eNB 10-1 determines whether the
user of the UE 20 is a heavy user. For example, the processing unit 103
determines that the user of the UE 20 is a heavy user when an amount of
10 data transmitted and received by the UE 20 in the past (which may be the
total amount of data in the past and the amount of data within the latest certain period) is equal to or greater than a threshold value. [0054]
When the user of the UE 20 is a heavy user, the processing proceeds
15 to Step C3.
[0055]
On the other hand, when the user of the UE 20 is not a heavy user,
the processing proceeds to Step C6.
[0056]
20 Step C3:
The processing unit 103 of the eNB 10-1 determines whether the UE 20 has a function of a wireless LAN terminal. [0057]
When the UE 20 has a function of a wireless LAN terminal, the
25 processing proceeds to Step C4.
[0058]
On the other hand, when the UE 20 does not have a function of a wireless LAN terminal, the processing proceeds to Step C5. [0059]

15 Step C4:
The processing proceeds to Step C4 when the UE 20 is moving at a
low speed, the user of the UE 20 is a heavy user, and the UE 20 has a
function of a wireless LAN terminal.
5 [0060]
In this case, the processing unit 103 of the eNB 10-1 selects the
E-UTRAN cell 11-2 as being a handover destination cell in a manner as
follows:
[0061]
10 The UE 20 is moving at a low speed. Thus, the E-UTRAN cells
11-2 to 11-4 are firstly selected, which are cells of a micro base station, a
pico base station, or a femto base station having a small cell diameter and
disposed for hot spot countermeasure.
[0062]
15 In addition, the UE 20 has a function of a wireless LAN terminal.
Thus, the E-UTRAN cell 11-2 having a function of a wireless LAN base
station is subsequently selected finally as being a handover destination cell
from among the E-UTRAN cells 11-2 to 11-4.
[0063]
20 This allows the UE 20 of the heavy user to be handed over to the
E-UTRAN cell 11-2 having a function of a wireless LAN base station.
Consequently, the load on the macro base station can be reduced.
[0064]
Step C5:
25 The processing proceeds to Step C5 when the UE 20 is moving at a
low speed, the user of the UE 20 is a heavy user, and the UE 20 does not
have a function of a wireless LAN terminal.
[0065]
In this case, the processing unit 103 of the eNB 10-1 selects the

16 E-UTRAN cell 11-3 as being a handover destination cell in a manner as
follows:
[0066]
The UE 20 is moving at a low speed. Thus, the E-UTRAN cells
5 11-2 to 11-4 are firstly selected, which are cells of a micro base station, a
pico base station, or a femto base station having a small cell diameter and disposed for hot spot countermeasure. [0067]
In addition, the UE 20 does not have a function of a wireless LAN
10 terminal, and the user of the UE 20 is a heavy user. Thus, the E-UTRAN
cell 11-3 not having a function of a wireless LAN base station and being a
cell for dynamically adding a communication capacity is subs equently
selected finally as being a handover destination cell from among the
E-UTRAN cells 11-2 to 11-4.
15 [0068]
This allows the UE 20 of the heavy user to be handed over to the
E-UTRAN cell 11-3 being a cell for dynamically adding a communication
capacity. Consequently, the load on the macro base station can be
reduced.
20 [0069]
Step C6:
The processing proceeds to Step C6 when the UE 20 is moving at a
low speed, and the user of the UE 20 is not a heavy user.
[0070]
25 In this case, the processing unit 103 of the eNB 10-1 selects the
E-UTRAN cell 11-4 as being a handover destination cell in a manner as follows: [0071]
The UE 20 is moving at a low speed. Thus, the E-UTRAN cells

17 11-2 to 11-4 are firstly selected, which are cells of a micro base station, a
pico base station, or a femto base station having a small cell diameter and
disposed for hot spot countermeasure.
[0072]
5 In addition, the user of the UE 20 is not a heavy user. Thus, the
E-UTRAN cell 11-4 not having a function of a wireless LAN base station
and not being a cell for dynamically adding a communication capacity is
subsequently selected finally as being a handover destination cell from
among the E-UTRAN cells 11-2 to 11-4.
10 [0073]
This allows the UE 20 of the ordinary user who is not a heavy us er
to be handed over to the E-UTRAN cell 11-4 not having a function of a
wireless LAN base station and not being a cell for dynamically adding a
communication capacity.
15 [0074]
This result facilitates handover of the UE 20 of a heavy user to a
cell having a function of a wireless LAN base station and to a cell for
dynamically adding a communication capacity. Consequently, the load
on the macro base station can be reduced.
20 [0075]
Step C7:
The processing proceeds to Step C7 when the UE 20 is moving at a
high speed.
[0076]
25 In this case, the processing unit 103 of the eNB 10-1 selects the
E-UTRAN cell 11-5 as being a handover destination cell in a manner as follows: [0077]
The UE 20 is moving at a high speed. Thus, the E-UTRAN cell

18 11-5 being a cell of a macro base station having a large cell diameter is
selected finally as being a handover destination cell.
(3) Advantageous Effects of Present Exemplary Embodiment
As described above, the present invention addresses some cases in
5 which the system information defined in 3GPP TS36.331 v12.1.0 (NPL 4)
and 3GPP TS25.331 v12.1.0 (NPL 5) may alone be insufficient for an eNB
to determine a handover destination cell of a UE.
[0078]
This problem becomes evident when the eNBs 10 are densely
10 arranged. Herein, assumed is a Heterogeneous Network where a cell
formed by a macro base station disposes therein a micro base station, a pico base station, or a femto base station that forms a cell having a cell diameter smaller than that of the macro base station. [0079]
15 For example, when a cell of a macro base station includes an area
where user traffic is concentrated (hot spot), it is necessary not to send
large-volume traffic occurring in the area to the macro base station as
much as possible. Thus, a source eNB has to select, as being a handover
destination cell of a UE, a cell of a base station with a function of a
20 wireless LAN base station or a cell for dynamically adding a
communication capacity. However, the service information defined in
3GPP TS36.331 v12.1.0 (NPL 4) and 3GPP TS25.331 v12.1.0 (NPL 5) alone does not allow determining whether a neighbour cell is a cell of a base station with a function of a wireless LAN base station or a cell for
25 dynamically adding a communication capacity. Accordingly,
large-volume traffic is sent to the macro base station, and this may deteriorate the user experience of many users by the increased load on the macro base station. [0080]

19 As a solution for the above-described problem, there is conceived a
method whereby a base station can use information (hereinafter, service
information) relating to whether a neighbour cell is a cell of another base
station with a function of a wireless LAN base station or a cell for
5 dynamically adding a communication capacity. However, when the base
station cannot automatically acquire and reflect the service information in
the processing, a telecommunications carrier constructing the
above-described Heterogeneous Network has to manually register the
service information of each neighbour cell for every disposition of a base
10 station. Since the man-hour of operation by the telecommunications
carrier increases with the increase in the number of base stations, the increase in Operational Expenditure (hereinafter, OPEX) is inevitable. [0081]
In contrast, the eNB 10 in the present exemplary embodiment
15 acquires, via the UE 20 that is in a connected state to the own cell, service
information of each neighbour cell (two new information elements "capacity-booster-cell-Capable" and "wLAN-Capable" are added) received by the UE 20, and registers the acquired service information with an NRT. [0082]
20 Therefore, the eNB 10 is able to obtain information that relates to
whether a neighbour cell is a cell of a base station with a function of a
wireless LAN base station or a cell for dynamically adding a
communication capacity, which is sufficient to determine a handover
destination cell of the UE 20. This allows the UE 20 to be handed over to
25 a cell of a base station with a function of a wireless LAN base station or a
cell for dynamically adding a communication capacity. [0083]
For example, large-volume traffic of the UE 20 of a heavy user occurring in a hot spot can be prevented from being sent to a macro base

20
station. Consequently, the load on the macro base station can be reduced.
[0084]
In addition, the eNB 10 in the present exemplary embodiment
acquires service information of each neighbour cell by itself and registers
5 the acquired service information of the neighbour cell with an NRT.
[0085]
Therefore, there is no need for a telecommunications carrier to
manually register the service information of the neighbour cell with the
NRT. Consequently, the OPEX can be reduced.
10 (4) Modification Examples of Present Exemplary Embodiment
The present invention has been described above with reference to
the exemplary embodiment. However, the present invention is not
limited to the above-described exemplary embodiment. Various
modifications that are understandable to those skilled in the art can be
15 made to the configuration and the detail of the present invention within the
scope of the present invention. The following describes modification
examples of the present exemplary embodiment.
(4-1) In the above-described exemplary embodiment, an eNB adds two information elements "capacity-booster-cell-Capable" and
20 "wLAN-Capable" to service information. However, an eNB does not
necessarily add both of the two information elements, but is only required
to add at least one of the two information elements. This configuration
also allows a UE to be handed over to a cell of a base station with a function of a wireless LAN base station or a cell for dynamically adding a
25 communication capacity, and produces an advantageous effect similar to
that of the above-described exemplary embodiment.
(4-2) In the above-described exemplary embodiment, an eNB does not
specify the capability of a UE from the UE Category prescribed in 3GPP
TS36.306 V12.0.0 (NPL 7). However, an eNB may specify the capability

21
of a UE from the UE Category. For example, it is conceivable that an
eNB determines that a user of a UE of Category 6 or Category 7 of the UE
Category is a heavy user.
(4-3) In the above-described exemplary embodiment, an eNB does not
5 include, in service information, an information element indicating
"whether a cell is part of a SCG." However, an eNB may include the
information element in service information. In general, a cell of an SeNB
has a cell diameter smaller than that of a cell of an MeNB, and is capable
of large-volume data communication. Thus, for example, it is
10 conceivable that a UE of a heavy user can be preferentially handed over to
part of cells of an SCG.
(4-4) In the above-described exemplary embodiment, an eNB does not include, in service information, an information element indicating "whether Machine to Machine (hereinafter, M2M) is used in a cell ."
15 However, an eNB may include the information element in service
information. For example, a UE using M2M is characterized in being
disposed in equipment or the like and transmitting information at a fixed
time of a day. Increase in the number of such UEs may possibly cause
congestion in an eNB. In addition, some eNBs include a mechanism for
20 controlling congestion. Thus, for example, it is conceivable that a UE
using M2M is preferentially handed over to a cell of an eNB with the mechanism for controlling congestion.
(4-5) In the above-described exemplary embodiment, handover control is
applied to handover between E-UTRAN cells. However, the handover
25 control in the above-described exemplary embodiment may be applied to
handover between an E-UTRAN cell and a cell of another wireless communication scheme (e.g., GSM EDGE Radio Access Network (GERAN), Code Division Multiple Access (CDMA) 2000, wireless LAN, and Worldwide Interoperability for Microwave Access (WiMAX)), and may be

22 applied to handover between cells of the other identical wireless
communication scheme.
(4-6) In the above-described exemplary embodiment, an eNB broadcasts
service information using SystemInformationBlockType1 message (see Fig.
5 4) defined in 3GPP TS36.331V12.1.0 (NPL 4). However, an eNB may
add a new information element to another kind of information broadcasted
in an LTE wireless communication system and to system information
broadcasted in a wireless communication system using a scheme other than
LTE.
10 (4-7) In the above-described exemplary embodiment, a UE reports, in a
procedure of execution of the ANR, service information including a new
added information element to an eNB. However, the service information
may be included in information that is reported from a UE by using a function called Minimization Drive Tests (hereinafter, referred to as MDT)
15 prescribed in 3GPP TS37.320 V12.0.0 (NPL 8). The MDT refers to a
function of making a UE used by a subscriber to take ov er the work of a telecommunications carrier who used to measure the communication quality of a cell while moving by an automobile on which a measuring instrument is mounted, and making an eNB to report a result of the
20 measurement. The MDT enables the reduction of the OPEX.
(4-8) In the above-described exemplary embodiment, an eNB adds two information elements "capacity-booster-cell-Capable" and
"wLAN-Capable" to service information. However, in addition to these
two information elements, an eNB may add another information element
25 that can enhance the degree of satisfaction of a user of an UE. Such
information elements that are conceivable are as follows:
∙Information element that indicates whether an eNB forming a cell is a
Relay Node (Hereinafter, referred to as a RN) (An RN is assumed to have
small coverage. Thus, for example, it is conceivable that a UE moving at

23
a high speed is not handed over to a cell of an RN. This makes it possible
to avoid deterioration of a User Experience.)
∙Information element that indicates whether a cell is a cell dedicated for
downlink communication or a cell prioritized for downlink communication
5 (For example, it is conceivable that a UE in execution of downloading data
may be handed over to the cell, whereas a UE in telephone communication
is not handed over to the cell.)
∙Information element that indicates whether a cell is split using the
function of Cell splitting executed by the function of an Active Antenna
10 System prescribed in 3GPP TR37.822 V1.2.0 (NPL 9) (When large-volume
traffic occurs permanently or frequently in a certain area, a cell can be
split. Thus, for example, it is conceivable that a UE of a heavy user i s
preferentially handed over to the split cell.) (4-9) In the above-described exemplary embodiment, an eNB acquires
15 service information of each neighbour cell by measurement report from an
UE. However, an eNB may acquire, by its own, service information of
each neighbour cell by using a function, called a Network Monitoring
Mode, of measuring a surrounding radio environment. Alternatively, an
eNB may acquire service information of each neighbour cell through a
20 message received from a neighbour eNB via an X2 interface, an Iur
interface, an Iurh interface, an Iurg interface or the like, through a RAN Information Management (hereinafter, referred to as RIM) procedure defined in 3GPP TS36.413 V12.1.0 (NPL 6), or from an Operation & Maintenance (O&M) server.
25 (4-10) In the above-described exemplary embodiment, a UE in a
RRC_CONNECTED state in an LTE network acquires service information
of each neighbour cell. However, as defined in 3GPP TS25.484V11.1.0
(NPL 9), a UE in an IDLE mode in a 3G network may acquire service information of each neighbour cell and report the acquired service

24 information to a base station.
(4-11) In the above-described exemplary embodiment, an eNB manages an
NRT. However, a device that manages a plurality of eNBs may manage
an NRT of each of the eNBs.
5 [0086]
Note that a part or all of the above-described exemplary
embodiments can be described as the following Supplementary notes but
the present invention is not limited to the following.
[Supplementary note 1]
10 A base station including:
a storage unit that stores a neighbour relation table; and
a processing unit, wherein
the storage unit
stores the neighbour relation table, and
15 the processing unit
receives service information of a neighbour cell that is transmitted
by another base station forming the neighbour cell adjacent to its own cell
and that includes at least one of an information element indicating whether
the other base station has a function of a wireless LAN base station and an
20 information element indicating whether the neighbour cell is a cell for
dynamically adding a communication capacity, and
registers the service information of the neighbour cell with the
neighbour relation table.
[Supplementary note 2]
25 The base station according to Supplementary note 1, wherein
the processing unit transmits, into the own cell, the service information of the own cell. [Supplementary note 3]
The base station according to Supplementary note 2, wherein

25 the processing unit further includes, in the service information of
the own cell, an information element indicating whether the own cell is
part of an SCG.
[Supplementary note 4]
5 The base station according to Supplementary note 2 or 3, wherein
the processing unit further includes, in the service information of
the own cell, an information element indicating whether M2M is used in
the own cell.
[Supplementary note 5]
10 The base station according to any one of Supplementary notes 2 to 4,
wherein
the processing unit further includes, in the service information of
the own cell, an information element indicating whether the local base
station is a relay node.
15 [Supplementary note 6]
The base station according to any one of Supplementary notes 2 to 5,
wherein
the processing unit further includes, in the service information of
the own cell, either an information element indicating whether the own cell
20 is a cell dedicated for downlink communication or an information element
indicating whether the own cell is a cell prioritized for downlink
communication.
[Supplementary note 7]
The base station according to any one of Supplementary notes 2 to 6,
25 wherein
the processing unit
broadcasts, within the own cell, the service information of the own
cell, and
receives, from a terminal in a connected state to the own cell, the

26 service information of the neighbour cell received by the terminal from the
neighbour cell.
[Supplementary note 8]
The base station according to any one of Supplementary notes 2 to 6,
5 wherein
the processing unit transmits the service information of the own
cell and receives the service information of the neighbour cell to and from
the other base station forming the neighbour cell via a predetermined
interface.
10 [Supplementary note 9]
The base station according to any one of Supplementary notes 2 to 8,
wherein
the processing unit determines a handover destination cell of a
terminal in a connected state to the own cell, based on the service
15 information of the neighbour cell registered with the neighbour relation
table.
[Supplementary note 10]
The base station according to Supplementary note 9, wherein
the processing unit determines a handover destination cell of a
20 terminal in a connected state to the own cell, further using information
indicating an amount of data transmitted and received by the terminal in
the past, a speed of movement of the terminal, and whether the terminal has
a function of a wireless LAN terminal.
[Supplementary note 11]
25 A wireless communication system including:
a terminal; and
a plurality of base stations, wherein
each of the plurality of base stations
receives service information of a neighbour cell that is transmitted

by another base station forming the neighbour cell adjacent to its own cell and that includes at least one of an information element indicating whether the other base station has a function of a wireless LAN base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity, and
registers the service information of the neighbour cell with a neighbour relation table. [Supplementary note 12]
The wireless communication system according to Supplementary note 11, wherein
each of the plurality of base stations transmits, into the own cell, the service information of the own cell. [Supplementary note 13]
The wireless communication system according to Supplementary note 12, wherein
each of the plurality of base stations
broadcasts, within the own cell, the service information of the own cell, and
receives, from a terminal in a connected state to the own cell, the service information of the neighbour cell received by the terminal from the neighbour cell. [Supplementary note 14]
The wireless communication system according to Supplementary note 12 or 13, wherein
each of the plurality of base stations determines a handover destination cell of a terminal in a connected state to the own cell, based on the service information of the neighbour cell registered with the neighbour relation table. [Supplementary note 15]

A communication method by a base station, including:
a reception step of receiving service information of a neighbour cell that is transmitted by another base station forming the neighbour cell adjacent to a own cell and that includes at least one of an information element indicating whether the other base station has a function of a wireless LAN base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity; and
a registration step of registering the service information of the neighbour cell with a neighbour relation table. [Supplementary note 16]
The communication method according to Supplementary note 15, further including
a transmission step of transmitting, into the own cell, the service information of the own cell. [Supplementary note 17]
The communication method according to Supplementary note 16, wherein
the transmission step includes broadcasting, within the own cell, the service information of the own cell, and
the reception step includes receiving, from a terminal in a
connected state to the own cell, the service information of the neighbour
cell received by the terminal from the neighbour cell.
[Supplementary note 18]
25 The communication method according to Supplementary note 16 or
17, further including
a determination step of determining a handover destination cell of a terminal in a connected state to the own cell, based on the service information of the neighbour cell registered with the neighbour relation

table. [0087]
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2014-85221, filed on April 17, 2014, the disclosure of which is incorporated herein in its entirety by reference.

WE CLAIM:
1. A base station comprising:
a storage unit; and
a processing unit, wherein
the storage unit
stores a neighbour relation table, and
the processing unit is configured to:
receive service information of a neighbour cell to its own cell, the service information being transmitted by another base station forming the neighbour cell to the own cell, the service information including at least one of an information element indicating whether the another base station has a function of a wireless LAN (Local Area Network) base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity, and
register the service information of the neighbour cell with the neighbour relation table.
2. The base station according to claim 1, wherein
the processing unit transmits, into the own cell, the service information of the own cell.
3. The base station according to claim 2, wherein
the processing unit
broadcasts, in the own cell, the service information of the own cell, and
receives, from a terminal in a connected state to the own cell, the service information of the neighbour cell received by the terminal from the neighbour cell.

4. The base station according to claim 2 or 3, wherein
the processing unit determines a handover destination cell of a terminal that is in a connected state to the own cell, based on the service information of the neighbour cell registered with the neighbour relation table.
5. A wireless communication system comprising:
a terminal; and
a plurality of base stations,
wherein each of the plurality of base stations is configured to:
receive service information of a neighbour cell to its own cell, the service information being transmitted by another base station forming the neighbour cell to the own cell, the service information including at least one of an information element indicating whether the another base station has a function of a wireless LAN (Local Area Network) base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity, and
register the service information of the neighbour cell with a neighbour relation table.
6. The wireless communication system according to claim 5, wherein
each of the plurality of base stations
broadcasts, within the own cell, the service information of the own cell, and
receives, from a terminal that is in a connected state to the own cell, the service information of the neighbour cell received by the terminal from the neighbour cell.
7. The wireless communication system according to claim 5 or 6,

wherein
each of the plurality of base stations determines a handover destination cell of a terminal that is in a connected state to the own cell, based on the service information of the neighbour cell registered with the neighbour relation table.
8. A communication method for use in a base station, comprising:
a reception step of receiving service information of a neighbour cell to its own cell, the service information being transmitted by another base station forming the neighbour cell to the own cell, the service information including at least one of an information element indicating whether the another base station has a function of a wireless LAN (Local Area Network) base station and an information element indicating whether the neighbour cell is a cell for dynamically adding a communication capacity; and
a registration step of registering the service information of the neighbour cell with a neighbour relation table.
9. The communication method according to claim 8, further
comprising
a transmission step of broadcasting, within the own cell, the service information of the own cell, wherein
the reception step comprises receiving, from a terminal that is in a connected state to the own cell, the service information of the neighbour 25 cell received by the terminal from the neighbour cell.
10. The communication method according to claim 8 or 9, further
comprising
a determination step of determining a handover destination cell of a

terminal that is in a connected state to the own cell, based on the service information of the neighbour cell registered with the neighbour relation table.