[000 1]
The present invention relates to a wireless base station, a mobile
station, a wireless communication system, a control method for a wireless
base station, and a program.
10 Background Art
[0002]
In recent years, since the communication areas of a plurality of
networks having different communication schemes are overlapped, mobile
stations are often connected to any of these networks and provided with
15 communication services. Examples of the above-mentioned
communication schemes include a GSM (Global System for Mobile
Communication), a UTRAN (Universal Terrestrial Access Network), and
an E-UTRAN (Evolved UTRAN).
With the recent increase in traffic, an attempt has been made to
20 reduce the load of a radio access network equipped with macro base
stations by locating small mobile phone base stations or wireless LAN
~,0
(WLAN: Wireless Local Area Network) base stations. Another attempt
has been made to reduce the load of a core network by sending the traffic
of mobile stations from small wireless base stations or wireless LAN s to
25 the external network (Internet) without a core network which is host to a
radio access network. A network established by combining networks
having different conununication schernes, as described above, is called a
HetN et (Hetro geneous Network).
[0003]
2
Regarding the HetN et, a method for cooperation between a wireless
LAN and a mobile phone network is described in NPL 1 (3GPP (3rd
Generation Partership Projet) TR 37.834 v12.0.0). In this method, a
mobile station measures the radio qualities of signals transmitted from
5 both the wireless LAN and the mobile phone network. The mobile station
then determines a network to be connected, on the basis of factors such as
the measurement results of the radio qualities in accordance with a policy
or a threshold set from the mobile phone network or an instruction from the
mobile phone network.
10 [0004]
PTL 1 (Japanese Unexamined Patent Application Publication No.
2004-260444) discloses a method for implementing a seamless handover
while reducing the processing load in a HetN et. In this method, a mobile
station measures the radio quality of a signal from a radio access station in
15 each of a plurality of networks having different communication schemes
and determines a radio access station to be connected on the basis of the
measurement results. A network controller which is host to a radio
access station controls the handover operation of a mobile station on the
basis of a radio access station to be connected, a network accommodating
20 the radio access station, and the moving speed of the mobile station.
In the above-mentioned methods described in NPL 1 and PTL 1, the
mobile station needs to measure the radio quality of a signal from a
network having each communication scheme. Therefore, the number of
signals, the radio qualities of \vhich are to be measured by the mobile
25 station, increases, and the power consumption of the mobile station, in turn,
Increases.
[0005]
To overcome this issue, PTL 2 (International Publication No. WO
2007 /080627) discloses a method for suppressing the increase of the power
3
consumption of a mobile station in a wireless communication system in
which the communication areas of a 3rd generation mobile communication
system (3G), a 4th generation mobile communication system (4G), and
Super 3G (S3G) intermediate between 3G and 4G are overlapped. In this
5 method, the mobile station selects signals, the radio qualities of which are
to be measured, from signals of each of 3G, S3G, and 4G in accordance
with the remaining level of the battery and determines a connection
destination from networks corresponding to the signals, the radio qualities
of which have been measured. Selecting signals, the radio qualities of
10 which are to be measured, can suppress the increase of the power
consumption of the mobile station compared to the case where the radio
qualities of signals of each of 3G, S3G, and 4G are measured.
[0006]
The problem that the power consumption of the mobile station
15 increases due to an increase in number of objects, the radio qualities of
which are to be measured, is not limited to a HetNet. This problem may
also arise inCA (Carrier Aggregation) defined in NPL 2 (3GPP TS 36.300
v12.1.0).
CA is a technique for transmitting and receiving data using a
20 maximum of five componet carriers (to be referred to as CCs hereinafter)
having a maximum of 20 MHz. In CA, the mobile station needs to
measure the radio qualities of signals having a plurality of frequency bands
to use CCs having different frequencies in combination, thus the power
consumption of the mobile station increases.
25 [0007]
The above-n1entioned problern son1etin1es arise even in DC (Dual
Connectivity) defined by NPL 3 (3GPP TR 36.842 v 12.0.0).
ln DC, a Master eNB (evolved NodeB) (to be referred to as an
MeNB hereinafter) and a Secondary eNB (to be referred to as an SeND
4
hereinafter) are defined. The mobile station exchanges control data with
the far MeNB and exchanges user data with the near SeNB. In DC, the
mobile station needs to measure the radio qualities of signals transmitted
in cells respectively formed by the MeNB and the SeNB, thu,s the power
5 consumption of the mobile station increases.
Citation List
Patent Literature
[0008]
PTL 1: Japanese Unexamined Patent Application Publication No.
10 2004-260444
PTL 2: International Publication No. WO 2007/080627
Non Patent Literature
[0009]
NPL 1: 3GPP TR 37.834 v12.0.0
15 NPL 2: 3GPP TS 36.300 v12.1.0
NPL 3: 3GPP TR 36.842 v12.0.0
20
Summary of Invention
Technical Problem
[0010]
According to the above described methods described in PTL 1 and
NPL 1, there is a problem that the power consumption of the mobile station
Increases.
According to the method disclosed in PTL 2, an attempt can be
made to suppress the increase of the power consumption of the mobile
25 station. In the method disclosed in PTL 2, however, the mobile station
selects signals, the radio qualities of which are to be measured, and
determines a connection destination on the basis of the rneasuren1ent
results. Therefore, according to the method disclosed in PTL 2, there is a
problen1 that the object, the radio quality of whic'h is to be measured by the
5
mobile station may not be controlled, in consideration of the network load
from the side of the wireless base station.
There is sometimes the case that, for example, the radio quality of a
signal from a mobile phone base station in a mobile station is better than
5 that of a signal from a wireless LAN base station, but nonetheless no more
data is wanted from the mobile station due to congestion of the mobile
phone base station. Even in such a case, in the method disclosed in PTL
2, the mobile station may select a signal from the mobile phone base
station as an object to be measured and thus determine the mobile phone
10 base station as a connection destination.
The above-mentioned issue has not been sufficiently examined even
in NPLs 2 and 3.
It is an object of the present invention to provide a wireless base
station, a mobile station, a wireless communication system, a control
15 method for a wireless base station, and a program which can control an
object, the radio quality of which is to be measured by the mobile station,
in consideration of the network load to attempt to suppress the increase of
the power consumption of the mobile station.
Solution to Problem
20 [00 11]
In order to achieve the above-described object, a wireless base
station according to the present invention includes:
a communication unit which communicates with a mobile station
which measures radio quality of a signal transmitted in each of a plurality
25 of cells;
an acquisition unit which acquires load inforn1ation related to a
load of a network including a wireless base station forming the cell~ and
a control unit w·hich receives infonnation indicating a tncasurctncnt
result of the radio quality of the signal transmitted in each of the plurality
6
of cells and a state of a battery of the mobile station, from the mobile
station via the communication unit, determines a signal, radio quality of
which is to be measured by the mobile station, on the basis of the
measurement results of the radio qualities and the state of the battery of
5 the mobile station, indicated in the received information, and the load
information acquired by the acquisition unit, and notifies the signal
determined to be measured to the mobile station via the communication
unit.
10
[0012]
In order to achieve the above-described object, a mobile station
according to the present invention includes:
a battery;
a communication unit which communicates with a wireless base
station;
15 a measuring unit which measures radio quality of a signal
transmitted in each of a plurality of cells; and
a control unit which transmits information indicating a
measurement result of the radio quality of the signal transmitted in each of
the plurality of cells, obtained by the measuring unit, and a state of the
20 battery of the mobile station, to the wireless base station via the
communication unit, and, upon being notified a signal, the radio quality of
which is to be measured, from the wireless base station via the
communication unit, causes the measuring unit to measure the radio quality
of the notified signal.
25 [00 13]
In order to achieve the above-described object, a wireless system
according to the present invention includes:
a mobile station; and a wireless base station which communicates
with the 1110 bile station,
7
wherein the mobile station measures radio quality of a signal
transmitted in each of a plurality of cells and transmits information
indicating a measurement result of the radio quality of the signal
transmitted in each of the plurality of cells and a state of a battery of the
5 mobile station to the wireless base station,
the wireless base station acquires load information related to a load
of a network including a wireless base station forming the cell, determines
a signal, radio quality of which is to be measured by the mobile station, on
the basis of the measurement results of the radio qualities and the state of
10 the battery of the mobile station, transmitted from the mobile station, and
the acquired load information, and notifies the signal determined to be
measured to the mobile station, and
the mobile station measures radio quality of the signal notified
from the wireless base station.
15 [0014]
20
In order to achieve the above-described object, a control method for
a wireless base station according to the present invention includes:
communicating with a mobile station which measures radio quality
of a signal transmitted in each of a plurality of cells;
acquiring load information related to a load of a network including
a wireless base station forming the cell; and
receiving information indicating a measurement result of the radio
quality of the signal transmitted in each of the plurality of cells and a state
of a battery of the mobile station, from the mobile station, determining a
25 signal, radio quality of which is to be measured by the mobile station, on
the basis of the measurement results of the radio qualities and the state of
the battery of the mobile station, indicated in the received infonnation, and
the load infortnation acquired by the acquisition unit, and notifying the
signal detennined to be tneasured to the tnobile station.
8
[0015]
In order to achieve the above-described object, a computer-readable
recording medium according to the present invention records a program for
causing a computer within a wireless base station to perform the processes
5 of:
communicating with a mobile station which measures radio quality
of a signal transmitted in each of a plurality of cells;
acquiring load information related to a load of a network including
a wireless base station forming the cell; and
10 receiving information indicating a measurement result of the radio
quality of the signal transmitted in each of the plurality of cells and a state
of a battery of the mobile station, from the mobile station, determining a
signal, radio quality of which is to be measured by the mobile station, on
the basis of the measurement results of the radio qualities and the state of
15 the battery of the mobile station, indicated in the received information, and
the load information acquired by the acquisition unit, and notifying the
signal determined to be measured to the mobile station.
20
Advantageous Effects of Invention
[00 16]
According to the present invention, an object, the radio quality of
which is to be measured by a mobile station, can be controlled in
consideration of the network load to attempt to suppress the increase of the
power consumption of the mobile station.
Brief Description of Drawings
25 [00 1 7]
[Pig. 1] Pig. 1 is a diagram illustrating the configuration of a wireless
communication system according to a first exemplary embodiment of the
present invention.
[Pig. 2] Pig. 2 is a block diagram illustrating the configuration of the main
9
part of an HeNB illustrated in Fig. 1.
[Fig. 3] Fig. 3 is a block diagram illustrating the configuration of the main
part of a UE illustrated in Fig. 1.
[Fig. 4] Fig. 4 is a diagram illustrating an exemplary environment to which
5 the present invention is applied.
[Fig. 5] Fig. 5 is a sequence chart illustrating the operations of the HeNB
and the UE illustrated in Fig. 1.
[Fig. 6] Fig. 6 is a view illustrating an exemplary structure of a
measurement report.
10 [Fig. 7] Fig. 7 is a flowchart illustrating the operation of a control unit
illustrated in Fig. 2.
[Fig. 8] Fig. 8 is a diagram illustrating signals, the radio qualities of which
are to be measured by the UE illustrated in Fig. 1.
[Fig. 9] Fig. 9 is a diagram illustrating the configuration of a wireless
15 communication system according to a second exemplary embodiment of the
present invention.
[Fig. 1 0] Fig. 10 is a block diagram illustrating the configuration of the
main part of an eNB illustrated iri Fig. 9.
[Fig. 11] Fig. 11 is a diagram illustrating an exemplary environment to
20 which the present invention is applied.
[Fig. 12] Fig. 12 is a sequence chart illustrating the operations of the eNB
and the UE illustrated in Fig. 9.
[Fig. 13] Fig. 13 is a diagram illustrating the configuration of a wireless
communication system according to a third exemplary embodiment of the
25 present invention.
[Fig. 14] Fig. 14 is a block diagram illustrating the configuration of the
main part of an MeNB illustrated in Fig. 13.
[Fig. 15] Fig. 15 is a diagram illustrating an exemplary environment to
which the present invention is applied.
10
[Fig. 16] Fig. 16 is a sequence chart illustrating the operations of the
MeNB and the UE illustrated in Fig. 13.
[Fig. 17] Fig. 17 is a block diagram illustrating another configuration of a
wireless base station according to the present invention.
5 [Fig. 18] Fig. 18 is a view illustrating another exemplary structure of a
measurement report.
Description of Embodiments
[00 18]
Embodiments of the present invention will be described below with
10 reference to the drawings.
[00 19]
(First Exemplary Embodiment)
Fig. 1 is a diagram illustrating the configuration of a wireless
communication system 1 according to a first exemplary embodiment of the
15 present invention.
The wireless communication system 1 illustrated in Fig. 1 includes
a UE (User Equipment) 2, an HeNB (Home eNB) 11, an HeNB-GW (Home
eNB Gateway) 12, (H)eNBs 13 and 14, an X2-GW 15, an EPC (Evolved
Packet Core) 16, a PG W (Packet Data Network Gateway) 17, an AND SF
20 (Access Network Discovery and Selection Function) 18, a N odeB 19, an
HNB (Home NodeB) 20, an HNB-GW (Home NodeB Gateway) 21, an RNC
(Radio Network Controller) 22, a 3 GCN (3rd Generation Core Network) 23,
a BTS (Base Tranceiver Station) 24, a BSC (Base Staion Controller) 25, a
2GCN (2nd Generation Core Network) 26, a WLAN AP (Wireless Local
25 Area Network Access Point) 27, an ePDG (evolved Packet Data Gateway)
28, and a PGW29.
[0020]
The HeNB 11 is a small wireless base station forming a cell as a
communi cRtion area which allows wireless communication with the lTE 2.
11
The HeNB wirelessly communicates with the UE 2 camping on the cell
formed by the HeNB, via a Uu interface using the L TE (Long Term
Evolution) scheme.
The HeNB-G W 12 is connected to the HeNB 11 via an S 1 interface
5 and manages the HeNB 11.
The (H)eNBs 13 and 14 are HeNBs or eNBs (so-called macro base
stations) and are wireless base stations forming cells. The (H)eNBs 13
and 14 wirelessly communicate with the UE 2 camping on the cell formed
by the (H)eNBs 13 and 14, using the L TE scheme. The (H)eNB 13 is
10 connected to the HeNB 11 via an X2 interface.
The X2-G W 15 is connected to the HeNB 11 and the (H)eNB 14 via
X2 interfaces. The X2-GW 15 relays communication between the HeNB
11 and the (H)eNB 14.
The HeNB 11, the HeNB-G W 12, the (H)eNBs 13 and 14, and the
15 X2-GW 15 configure an E-UTRAN 3, that is, an E-UTRAN network.
[0021]
The EPC 16 is a core network device compatible with the E-UTRAN
3. The EPC 16 is connected to the HeNB-G W 12 and the (H)eNBs 13 and
14 via S 1 interfaces. The EPC 16 performs an authentication, movement
20 control, bearer management, billing, QoS (Quality of Service) control and
the like.
25
The PG W 1 7 is connected to the EPC 16 and connected to the
Internet 7 via an SGi interface. The PGW 17 performs data transfer
between the E-UTRAN 3 and the Internet 7.
The ANDSF 18 provides data (for example, a policy) for assisting
the UE 2 in discovering and connecting to a network in accordance with a
policy defined by the operator to the UE 2 via an S 14 interface. The
above-mentioned data providing is done in response to requests for access
network discovery information fron1 the lTE 2.
12
[0022]
Currently, no interfaces are defined between the ANDSF 18 and
other nodes (for example, the HeNB 11, the (H)eNBs 13 and 14, the HNB
20, the RNC 22, and the BSC 25). The following description assumes
5 that interfaces referred to as ltf-X (ltf-X interfaces) are defined between
the ANDSF 18 and other nodes.
Referring to Fig. 1, the HeNB-G W 12 is not indispensable. The
(H)eNBs 13 and 14 are connected to the EPC 16 without the HeNB-G W 12.
Referring again to Fig. 1, the X2-GW 15 is not indispensable either. The
10 HeNB 11 is directly connected to the (H)eNB 13 without the X2-G W 15.
[0023]
The N odeB 19 is a wireless base station (so-called macro base
station) forming a cell. The N odeB 19 wirelessly communicates with the
UE 2 camping on the cell formed by the NodeB 19, using the UTRAN
15 scheme.
The HNB 20 is a small wireless base station forming a cell. The
HNB 20 wirelessly communicates with the UE 2 camping on the cell
formed by the HNB 20, using the UTRAN scheme.
The HNB-GW 21 is connected to the HNB 20 via an lub interface
20 and manages the HNB 20.
The RNC 22 is connected to the NodeB 19 via an lub interface and
connected to the HNB~GW 21 via an lur interface. The RNC 22 performs,
for example, management and handover control of the N odeB 19 and the
HNB 20. The RNC 22 is further connected to the BSC 25 via an lurg
25 interface.
The NodeB 19, the HNB 20, the HNB-GW 21, and the RNC 22
configure a UTRAN 4, that is, a UTRAN network.
[0024]
The 3GCN 23 is a core network device compatible with the UTRAN
13
4. The 3GCN 23 is connected to the HNB-GW 21 and the RNC 22 via lu
interfaces and connected to the Internet 7 via a Gi interface. The 3 GCN
23 performs, for example, data transfer between the UTRAN 4 and the
Internet 7.
5 [0025]
The BTS 24 is a wireless base station forming a cell. The BTS 24
wirelessly communicates with the UE 2 camping on the cell formed by the
BTS 24, using the GSM scheme.
The BSC 25 is connected to the BTS 24 via an Abis interface and
10 performs, for example, control of the BTS 24.
The BTS 24 and the BSC 25 configure a GSM 5, that is, a GSM
network.
[0026]
The 2GCN 26 is a core network device compatible with the GSM 5.
15 The 2GCN 26 is connected to the BSC 25 via an A interface and connected
to the Internet 7 via a Gi interface. The 2GCN 26 performs, for example,
data transfer between the GSM 5 and the Internet 7.
[002 7]
The WLAN AP 27 is a wireless base station (WLAN base station)
20 forming a cell. The WLAN AP 27 wirelessly communicates with the UE
2 camping on the cell formed by the WLAN AP 2 7, using the WLAN
scheme. The WLAN AP 27 configures a WLAN 6, that is, a WLAN
network.
[0028]
25 The ePDG 28 is a core network dev_ice compatible with the WLAN 6.
The ePDG 28 relays traffic between the WLAN AP 27 and the PGW 29.
The PGW 29 is connected to the ePDG 28 and connected to the
Internet 7 via an SGi interface. The PGW 29 performs, for example, data
transfer between the WLAN 6 and the Internet 7.
14
Wireless communication between the WLAN AP 27 and the UE 2 is
done using an SWu interface or an S2c interface. When an SWu interface
is used, traffic may directly flow between the WLAN AP 2 7 and the PG W
29 via an S2a interface and may flow between them via an S Wn interface
5 and an S2b interface upon passing through the ePDG 28. When an S2c
interface is used, traffic may directly flow between the WLAN AP 27 and
the PGW 29 via the S2c interface and may tlow between them via the S2c
interface upon passing through the ePDG 28.
10
[0029]
The UE 2 is a mobile station capable of wirelessly communicating
with a wireless base station configuring each network including the
E-UTRAN 3, the UTRAN 4, the GSM 5, and the WLAN 6. The UE 2
measures the radio qualities of signals transmitted in a plurality of cells
(cells formed by wireless base stations configuring the respective
15 networks) and transmits the measurement results to a communicating
wireless base station.
[003 0]
The configurations of the HeNB 11 and the UE 2 will be described
below. Since the configurations of other nodes are well known to those
20 skilled in the art and are not directly concerned with the present invention,
a description thereof will not be given.
[0031]
The configuration of the HeNB 11 will be described first.
Fig. 2 is a block diagram illustrating the configuration of the main
25 part of the HeNB 11.
The HeNB 11 illustrated in Fig. 2 includes a communication unit
101, a storage unit 102, and a control unit 103. The storage unit 102 is an
exemplary acquisition unit.
The communication unit 101 wirelessly communicates with the UE
15
2.
The storage unit 102 stores various types of information. The
storage unit 102 further acquires and stores load information related to the
load of each network including the E-UTRAN 3, the UTRAN 4, the GSM 5,
5 and the WLAN 6 that are radio access networks and core networks
respectively corresponding to them.
The control unit 103 receives information indicating the
measurement result of the radio quality of a signal transmitted in each of a
plurality of cells and the state of the battery of the UE 2, from the UE 2 via
10 the communication unit 101. The control unit 103 determines a signal,
the radio quality of which is to be measured by the UE 2, on the basis of
the measurement results of the radio qualities and the state of the battery
of the UE 2, indicated in the received information, and the load
information stored in the storage unit 102. The control unit 103 transmits
15 a message indicating the signal determined to be measured to the UE 2 via
the communication unit 101.
[0032]
The configuration of the UE 2 will be described below.
Fig. 3 is a block diagram illustrating the configuration of the main
20 part of the UE 2.
The UE 2 illustrated in Fig. 3 includes a communication unit 201, a
measuring unit 202, a storage unit 203, a battery 204, and a control unit
205.
The communication unit 201 wirelessly communicates with wireless
25 base stations (the HeNB 11, the (H)eNBs 13 and 14, the N odeB 19, the
HNB 20, the BTS 24, and the WLAN AP 27).
The measuring unit 202 measures the radio quality of a signal
transmitted in a plurality of cells (cells formed by wireless base stations
configuring the respective networks), which has been received via the
16
communication unit 201.
The storage unit 203 stores various types of information.
The battery 204 supplies power for operating the UE 2.
The control unit 205 transmits information indicating the
5 measurement results of the radio qualities obtained by the measuring unit
202 and the state of the battery 204 to the HeNB 11, via the communication
unit 201. Upon receiving a message indicating a signal, the radio quality
of which is to be measured, from the HeNB 11 via the communication unit
201, the control unit 205 causes the measuring unit 202 to measure the
10 radio quality of the signal indicated in the received message.
[0033]
The operations of the HeNB 11 and the UE 2 will be described
below.
The following description assumes that the UE 2 camps on an
15 E-UTRAN cell 11 a, that is, a cell formed by the HeNB 11 and has
established connection (RRC (Radio Resource Control) connection) to the
HeNB 11, as illustrated in Fig. 4. Assume again that the UE 11 also
camps on cells respectively formed by the (H)eNBs 13 and 14, the HNB 20,
the BTS 24, and the WLAN AP 27. The cells formed by the (H)eNBs 13
20 and 14, the HNB 2 0, the B T S 24, and the WLAN AP 2 7 will be referred to
as E-UTRAN cells 13a and 14a, a UTRAN cell 20a, a GSM cell 24a, and a
WLAN cell 27a, respectively, hereinafter. The following description
further assumes that a frequency X is used in the E-UTRAN cell 11 a, a
frequency Y is used in the E-UTRAN cell 13a, and a frequency Z is used in
25 the E-UTRAN cell 14a.
[0034]
Fig. 5 is a sequence chart illustrating the operations of the HeNB 11
and the UE 2.
First, the control unit 103 of the HeNB 11 requests a measurement
17
report to the UE 2 via the communication unit 101 (step S 11 ). The
control unit 103 requests the measurement of the radio quality of a signal
transmitted in each of the E-UTRAN cells 11 a, 13 a, and 14a, the UTRAN
cell 20a, the GSM cell 24a, and the WLAN cell 27a on which the UE 2
5 camps.
[0035]
The storage unit 102 acquires and stores load information related to
the load of a network in advance. More specifically, the storage unit 102
acquires and stores, for example, load information (load information
10 related to core networks) for the EPC 16, the 3GCN 23, the 2GCN 26, and
the ePDG 28 configuring core networks. The storage unit 102 further
acquires and stores load information (load information related to radio
access networks) for the (H)eNBs 13 and 14, the N odeB 19, the RNC 22,
the BTS 24, the BSC 25, the WLAN AP 27, and the like configuring radio
15 access networks.
Specific examples of the load information related to core networks
include pieces of information on BHCA (Busy Hour Call Attempts), the
number of connections and the like. Specific examples of the load
information related to radio access networks include the available radio
20 resources and the capacities of interfaces.
[0036]
Such load information can be acquired from other wireless base
stations, host devices, management devices, or the like. A specific
method for acquiring load information is not directly concerned with the
25 present invention and will not be described in detail herein, but the
following method is available. For example, a method is available for
exchanging pieces of information on available radio resources between
radio access networks having different schemes, in accordance with a
procedure called RAN Information Management defined in NPL 2.
18
Another method is available for exchanging pieces of information on
available radio resources between radio access networks having the same
scheme or different schemes, via an X2 interface and lurh, lurg, and lur
interfaces and the like that are interfaces between HNBs (not illustrated in
5 Fig. 1).
[003 7]
In response to the request for a measurement report from the HeNB
11, the control unit 205 of the UE 2 causes the measuring unit 202 to
measure the radio quality of a signal transmitted in each cell designated in
10 the measurement report. Specific examples of the radio quality include
RSRP (Referense Signal Received Power), RSRQ (Referense Signal
Received Quality), and Ec/Io (desired signal power/overall received
power). The control unit 205 causes the storage unit 203 to store the
measurement results obtained by the measuring unit 202. The control
15 unit 205 further measures the state (remaining level) of the battery 204 and
causes the storage unit 203 to store the measurement result.
[0038]
The control unit 205 transmits information indicating the
measurement result of the radio quality of each cell and the state
20 (remaining level) of the battery 204, stored in the storage unit 203, to the
HeNB 11 via the communication unit 201 as a measurement report (step
s 13).
Fig. 6 is a view illustrating an exemplary structure of a
m~asurement report.
25 The UE 2 transmits information obtained by adding a parameter (an
area marked with a dotted frame in Fig. 6) stated as batteryLevel to the
measurement report (MeasResults Information) defined in 3GPP TS 36.331
v12.1.0. The batteryLevel represents the percentage of the remaining
level of the battery 204.
19
[003 9]
Referring back to Fig. 5, upon receiving the measurement report
transmitted from the UE 2 via the communication unit 101, the control unit
103 of the HeNB 11 causes the storage unit 102 to store the received
5 measurement report. The control unit 103 sets the measurement report
and the load information stored in the storage unit 102 as inputs to an
evaluation function and determines a signal, the radio quality of which is
to be measured by the UE 2, on the basis of outputs from the evaluation
function.
10 [0040]
Fig. 7 is a flowchart illustrating the operation of the control unit
103 in determining a signal, the radio quality of which is to be measured.
The following description assumes that the load information of core
networks stored in the storage unit 102 indicates that the relative
15 magnitude of load descends in the EPC 16, the 3 GCN 23, the 2GCN 26, and
the ePDG 28 in this order. In other words, the correlation of the load of
each node is EPC 16 > 3GCN 23 > 2GCN 26 > ePDG28. The radio load
information of radio access networks stored in the storage unit 102
indicates that the amount of available radio resources ascends in the GSM
20 cell 24a, the UTRAN cell 20a, the E-UTRAN cell 13a, the WLAN cell 27a,
and the E-UTRAN cell 14a in this order. In other words, the correlation
of the amount of available radio resources is GSM Cell 24a < UTRAN Cell
20a < E-UTRAN Cell 13a < WLAN Cell 27a < E-UTRAN Cell 14a. The
following description assumes that the radio quality of each cell satisfies
25 GSM Cell 24a > UTRAN Cell 20a > E-UTRAN Cell 13a > E-UTRAN Cell
14a > WLAN Cell 27a.
[0041]
If the radio quality of each cell satisfies GSM Cell 24a > UTRAN
Cell 20a > E-UTRAN Cell 13a > E-UTRAN Cell 14a > WLAN Cell 27a
20
(step S21 ), the control unit 103 proceeds to the process in step S22.
The control unit 103 determines in step S22 whether the remaining
level of the battery 204 of the UE 2 indicated in the measurement report is
equal to or higher than a threshold.
5 If it is determined that the remaihing level of the battery 204 is
equal to or higher than the threshold (Yes in step S22), the control unit 103
determines whether the congestion of the EPC 16, the 3GCN 23, and the
2GCN 26 is equal to or higher than a threshold (step S23).
If it is determined that the congestion of the EPC 16, the 3 GCN 23,
10 and the 2GCN 26 is equal to or higher than the threshold (Yes in step S23 ),
the control unit 103 proceeds to the process in step S25 (to be described
15
later). If it is determined that the congestion of the EPC 16, the 3GCN 23,
and the 2GCN 26 is lower than the threshold (No in step S23 ), the control
unit 103 proceeds to the process in step S26 (to be described later).
If it is determined that the remaining level of the battery 204 is
lower than the threshold (No in step S22), the control unit 103 determines
whether the congestion of the EPC 16, the 3 GCN 23, and the 2GCN 26 is
equal to or higher than a threshold (step S24).
If it is determined that the congestion of the EPC 16, the 3 GCN 23,
20 and the 2GCN 26 is equal to or higher than the threshold (Yes in step S24 ),
the control unit 103 proceeds to the process in step S27 (to be described
later). If it is determined that the congestion of the EPC 16, the 3GCN 23,
and the 2GCN 26 is lower than the threshold (No in step S24 ), the control
unit 103 proceeds to the process in step S28 (to be described later).
25 [0042]
The process in each of steps S25 to S28 will be described below.
The process in step S25 will be described first.
When the process in step S25 is performed, the remaining level of
the battery 204 of the U E 2 is equal to or higher than a threshold (the
21
remaining level has a margin), and the congestion of the EPC 16, the 3GCN
23, and the 2GCN 26 is equal to or higher than a threshold (congested
state).
In this case, the control unit 103 determines a signal, the radio
5 quality of which is to be measured by the UE 2, in consideration of
followings:
a) the 2GCN 26 is congested, but its degree of congestion is
relatively small (load information related to core networks);
b) the ePDG 2 8 is not congested;
10 c) the available radio resources are relatively small in the GSM cell
15
24a, but are relatively large in the WLAN cell 2 7 a (load information
related to radio access networks); and
d) the radio quality of the GSM cell 24a is relatively good, while
the radio quality of the WLAN cell 27a is relatively poor.
In c), the evaluation of the WLAN cell 27a is high (its amount of
available radio resources is large), while the evaluation of the GSM cell
24a is low (its amount of available radio resources is small). In d), the
evaluation of the WLAN cell 27a is high (its radio quality is good), while
the evaluation of the GSM cell 24a is low (its radio quality is poor).
20 Hence, some or all of the evaluations of the WLAN cell 27a and the GSM
cell 24a are cancelled out. However, the control unit 103 takes into
consideration the fact that the WLAN cell 27a and the GSM cell 24a are
evaluated higher than the remaining cells in a) and b) and determines a
signal transmitted in the WLAN cell 27a and a signal transmitted in the
25 GSM cell 24a as signals, the radio qualities of which are to be measured.
The control unit 103 causes the storage unit 102 to store information
indicating that these signals have been determined as signals, the radio
qualities of which are to be measured by the UE 2. The above-mentioned
determination logic is merely an example, and the control unit 103 may
22
determine a signal, the radio quality of which is to be measured by the UE
2, in accordance with other types of determination logic.
[0043]
The process in step S26 will be described next.
5 When the process in step S26 is performed, the remaining level of
the battery 204 of the UE 2 is equal to or higher than a threshold (the
remaining level has a margin), and the congestion of the EPC 16, the 3GCN
23, and the 2GCN 26 is lower than a threshold (non-congested state).
In this case, the control unit 103 determines a signal, the radio
10 quality of which is to be measured by the UE 2, in consideration of
following a) to c):
a) the EPC 16 is not congested;
b) the E-UTRAN cell 13a and the E-ETRAN cell 14a have a certain
amount of available radio resources or more (load information related to
15 radio access networks); and
c) the radio qualities of the E-UTRAN cell 13 a and the E-ETRAN
cell 14a are relatively not poor.
In a), the GSM cell 24a and the E-UTRAN cells 13a and 14a have
the same evaluation in terms of "not congested." In b), the E-UTRAN
20 cell 13a and the E-UTRAN 14a are evaluated higher (their amounts of
available radio resources are larger) than the GSM cell 24a. In c), the
GSM cell 24a and the E-UTRAN cell 13 a and the E-UTRAN 14a have the
same evaluation in terms of "relatively not poor." As a result of taking
these facts into consideration, the control unit 103 determines a signal
25 having the frequency Y transmitted in the E-UTRAN cell 13a and a signal
having the frequency Z transmitted in the E-ETRAN cell 14a as signals, the
radio qualities of which are to be measured. The control unit 103 causes
the storage unit 102 to store information indicating that these signals have
been determined as signals, the radio qualities of which are to be measured
23
by the UE 2. The above-mentioned determination logic is merely an
example, and the control unit 103 may determine a signal, the radio quality
of which is to be measured by the UE 2, in accordance with other types of
determination logic.
5 [0044]
The process in step S27 will be described next.
When the process in step S2 7 is performed, the remaining level of
the battery 204 of the UE 2 is lower than a threshold (the remaining level
has no margin), and the congestion of the EPC 16, the 3 GCN 23, and the
10 2GCN 26 is equal to or higher than a threshold (congested state).
In this case, the control unit 103 determines a signal, the radio
quality of which is to be measured by the UE 2, in consideration of
following a) to e):
a) the 2GCN 26 is congested, but its degree of congestion is
15 relatively small (load information related to core networks);
b) the ePDG 28 is not congested;
c) the amount of available radio resources is relatively small in the
GSM cell 24a, but is relatively large in the WLAN cell 27a (load
information related to radio access networks);
20 d) the radio quality of the GSM cell 24a is relatively good, while
the radio quality of a WLAN cell 41-1 is relatively not good; and
e) since the remaining level of the battery 204 has no margin,
signals to be measured need to be narrowed down as much as possible.
The control unit 103 weights c) and e), among above-mentioned a)
25 to e), in the evaluation function and determines a signal, the radio quality
of which is to be measured by the UE 2. As a result, the control unit 103
determines a signal transn1i tted in the WLAN cell 2 7 a as an object, the
radio quality of which is to be measured. The control unit 103 causes the
storage unit 102 to store information indicating that the signal transmitted
24
in the WLAN cell 41-1 has been determined as a signal, the radio quality of
which is to be measured by the UE 2.
[0045]
The process in step S28 will be described next.
5 When the process in step S28 is performed, the remaining level of
the battery 204 of the UE 2 is lower than a threshold (the remaining level
has no margin), and the congestion of the EPC 16, the 3 GCN 23, and the
2GCN 26 is lower than a threshold (non-congested state).
In this case, the control unit 103 determines a signal, the radio
10 quality of which is to be measured by the UE 2, in consideration of
following a) to d):
a) the EPC 16 is not congested;
b) the E-UTRAN cell 13a and the E-ETRAN cell 14a have a certain
amount of available radio resources or more (load information related to
15 radio access networks);
c) the radio qualities of the E-UTRAN cell 13a and the E-ETRAN
cell 14a are relatively not poor, and the radio quality of the E-UTRAN cell
13a is better than that of the E-ETRAN cell 14a; and
d) since the remaining level of the battery 204 has no margin,
20 signals to be measured need to be narrowed down as much as possible.
The control unit 103 weights c) and d), among above-mentioned a)
to d), in the evaluation function and determines a signal, the radio quality
of which is to be measured by the UE 2. As a result, the control unit 103
determines a signal having the frequency Y transmitted in the E-UTRAN
25 cell 13a as a signal, the radio quality of which is to be measured. The
control unit 103 causes the storage unit 102 to store information indicating
that the signal having the frequency Y transmitted in the E-UTRAN cell
13a has been determined as a signal, the radio quality of \Vhich is to be
measured by the UE 2.
25
[0046]
Fig. 7 illustrates an exemplary operation of the control unit 103
when the radio quality of each cell satisfies GSM Cell 24a > UTRAN Cell
20a > ·E-UTRAN Cell 13a > E-UTRAN Cell 14a > WLAN Cell 27a. The
5 control unit 103 determines a signal, the radio quality of which is to be
measured by the UE 2, in accordance with determination logic which takes
the state of the battery of the UE 2 into consideration as well, for each
state of the radio quality of each cell.
10
[004 7]
Referring back to Fig. 5, the control unit 103 gives a notification of
the signal that has been determined as a signal, the radio quality of which
is to be measured by the UE 2, and stored in the storage unit 102, via the
communication unit 101 (step S 15). In other words, the control unit 103
transmits a message indicating the communication scheme and frequency
15 of the signal determined as an object, the radio quality of which is to be
measured, to the UE 2 via the communication unit 101.
[0048]
Upon being notified the signal, the radio quality of which is to be
measured, via the communication unit 201, the control unit 205 of the UE 2
20 causes the measuring unit 202 to measure the radio quality of the notified
signal (step S 16).
Fig. 8 is a diagram illustrating objects, the radio qualities of which
are to be measured by the UE 2, before and after the notification is given
from the HeNB 11. Referring to Fig. 8, a signal transmitted in the WLAN
25 cell 27a and a signal transmitted in the GSM cell 24a are assumed to be
notified as signals, the radio qualities of which are to be measured.
Before giving the notification from the HeNB 11, the UE 2
measures the radio qua 1i ties of each of the E -lJ T RAN c e 11 s l 1 a, 1 3 a, and
14a, the UTRAN cell 20a, the GSM cell 24a, and the WLAN cell 27a, as
" )
26
illustrated in Fig. 8. On the other hand, after giving the notification from
the HeNB 11, the UE 2 measures the radio qualities of only the GSM cell
24a and the WLAN cell 27a. This can reduce the number of signals, the
radio qualities of which are to be measured, thus the increase of the power
5 consumption of the UE 2 can be suppressed.
[0049]
In this manner, according to the present exemplary embodiment, the
HeNB 11 includes a communication unit 101 which communicates with the
UE 2, a storage unit 102 which acquires and stores load information for a
10 network, and a control unit 103. The control unit 103 receives
information indicating the measurement results of the radio qualities of a
plurality of cells and the state of the battery 204 of the UE 2 from the UE 2,
and determines a signal, the radio quality of which is to be measured by the
UE 2, on the basis of the measurement results of the radio qualities, the
15 state of the battery 204, and the load information. The control unit 103
notifies the signal determined to be measured to the UE 2.
[0050]
The increase of the power consumption of the UE 2 can be
suppressed by controlling an object, the radio quality of which is to be
20 measured by the UE 2, in consideration not only of the state of the battery
204 of the UE 2 but also of the network load.
Controlling an object, the radio quality of which is to be measured,
in consideration of the network load, allows the use of a signal in a cell
provided with available radio resources in large amounts as an object, the
25 radio quality of which is to be measured, to improve the rate of handover
success of the UE 2.
Controlling an object, the raJio 4uality of which is to be measured,
in consideration of the netw·ork load allo\vs selection of a cell in a network
having less load than other networks as a connection destination to
27
improve the throughput.
Setting only some of signals among signals in a plurality of cells
having different communication schemes or frequencies as objects to be
measured can lead to the suppression of the interference to improve the
5 throughput of the entire wireless communication system 1.
[0051]
The wireless communication system 1 has been described by taking
one equipped with the E-UTRAN 3, the UTRAN 4, the GSM 5, and the
WLAN 6 as an example in the present exemplary embodiment, the present
10 invention is not limited to this, and the wireless communication system 1
may be equipped with only some of the above-mentioned plurality of
networks. The wireless communication system 1 may be equipped with,
for example, only the GSM 5 and the WLAN 6.
15
[0052]
(Second Exemplary Embodiment)
Fig. 9 is a diagram illustrating the configuration of a wireless
communication system 1 a according to a second exemplary embodiment of
the present invention.
The wireless communication system 1 a according to the present
20 exemplary embodiment is different from the wireless communication
system 1 according to the first exemplary embodiment in that in the former
the HeNB 11 and the HeNB-GW 12 are omitted and an eNB 30 is added.
The eNB 3 0 is a wireless base station forming a cell. The eNB 3 0
wirelessly communicates with a UE 2 camping on the cell formed by the
25 eNB 30, using the L TE scheme. Assume herein that in the present
exemplary embodiment, CA is performed between the cNB 3 0 and the UE
2.
[0053]
The configuration of the eNB 30 will he described below.
28
Fig. 10 is a block diagram illustrating the configuration of the main
part of the eNB 30.
The eNB 30 illustrated in Fig. 10 includes a communication unit
301, a storage unit 302, and a control unit 303. The storage unit 302 is an
5 exemplary acquisition unit.
The communication unit 3 01 wirelessly communicates with the UE
2.
The storage unit 3 02 stores various types of information such as
load information.
10 The control unit 3 03 receives information indicating the
measurement results of the radio qualities and the state of a battery 204 of
the UE 2 from the UE 2 via the communication unit 301. The control unit
303 determines a CC, the radio quality of which is to be measured by the
UE 2, on the basis of the measurement results of the radio qualities and the
15 state of the battery 204 of the UE 2, indicated in the received information,
20
and the load information stored in the storage unit 3 02. The control unit
303 transmits a message indicating the CC determined to be measured to
the UE 2 via the communication unit 301.
[0054]
The operations of the eNB 30 and the UE 2 will be described below.
The following description assumes that the eNB 30 forms an
E-UTRAN cell 30a which uses a frequency band A including two CCs that
are unit frequency bands, and an E-UTRAN cell 3 Ob which uses a
frequency band B including three CCs, as illustrated in Fig. 11. Assume
25 again that the UE 2 camps on the E-UTRAN cell 30a and has established
RRC connection, but it is also included in the coverage of the E-UTRAN
cell 30b.
L0055J
Fig. 12 is a sequence chart illustrating the operations of the eNB 3 0
29
and the UE 2.
First, the control unit 303 of the eNB 30 requests a measurement
report to the UE 2 via the communication unit 301 (step S31 ). The
control unit 303 requests the measurement of the radio qualities of the
5 E-UTRAN cells 30a and 30b. The storage unit 302 acquires and stores
load information in advance. Since the details of load information to be
acquired and the method for acquiring load information are the same as
those in the first exemplary embodiment, a description thereof will be
omitted.
10 [0056]
In response to the request for a measurement report from the eNB
30, a control unit 205 of the UE 2 causes a measuring unit 202 to measure
the radio qualities of signals transmitted in the E-UTRAN cells 30a and
30b designated in the measurement report (step S32). A frequency band
15 A including two CCs is used in the E-UTRAN cell 30a, and a frequency
band B including three CCs is used in the E-UTRAN cell 30b, as described
above. The measuring unit 202 measures radio quality for each CC in the
frequency band of each cell.
The control unit 205 causes the storage unit 203 to store the
20 measurement results (the radio quality of each cell) obtained by the
measuring unit 202. The control unit 205 further measures the state
(remaining level) of the battery 204 and causes the storage unit 203 to
store the measurement result.
[0057]
25 The control unit 205 transmits information indicating the
measurement result of the radio quality of each cell and the state
(remaining level) of the battery 204, stored in the storage unit 203, to the
eNB 30 via a communication unit 201 as a measurement report (step S33).
The control unit 205 transmits information obtained by adding a parameter
5
30
stated as battery Level representing the percentage of the remaining level of
the battery 204 to the measurement report (MeasResults Information) of
the radio qualities, as in the first exemplary embodiment.
[0058]
lJpon receiving the measurement report transmitted from the UE 2
via the communication unit 301, the control unit 303 of the eNB 30 causes
the storage unit 302 to store the received measurement report. The
control unit 303 determines a CC to be used by the UE 2, on the basis of
the measurement report and the load information stored in the storage unit
10 3 02. When, for example, the remaining level of the battery 204 of the UE
2 is low, the control unit 303 determines to cause the UE 2 to use not the
CCs included in the frequency band B used in the E-UTRAN cell 30b but
only one CC included in the frequency band A used in the E-UTRAN cell
30a. Further, when, for example, the radio quality of the E-UTRAN cell
15 30b is poor, or a few radio resources are available in the E-UTRAN cell
3 Ob, the control unit 3 03 determines not to cause the UE 2 to use the CCs
included in the frequency band B.
The control unit 3 03 determines the CC determined to be used by
UE 2 as a CC, the radio quality of which is to be measured by the UE 2, and
20 causes storage unit 302 to store the CC.
[0059]
The control unit 303 notifies the CC that has been determined as an
object, the radio quality of which is to be measured by the UE 2, and stored
in the storage unit 302, via the communication unit 301 (step S35). In
25 other words, the control unit 3 03 transmits a message indicating the CC
determined as an object, the radio quality of which is to be measured, to
the UE 2 via the communication unit 101.
[0060]
TJpon being notified the CC, the radio quality of which is to be
31
measured, via the communication unit 201, the control unit 205 of the UE 2
causes the storage unit 203 to store the notified CC. The control unit 205
causes the measuring unit 202 to measure the radio quality of the CC stored
in the storage unit 203. The control unit 205 further causes the
5 communication unit 201 to continue communication with the eNB 30 using
the CC stored in the storage unit 203.
[0061]
In this manner, according to the present exemplary embodiment, the
eNB 30 includes a communication unit 301 which communicates with the
10 UE 2, a storage unit 302 which acquires and stores load information for a
network, and a control unit 3 03. When CA is performed, the control unit
303 receives information indicating the measurement results of the radio
qualities of cells and the state of the battery 204 from the UE 2, and
determines a CC, the radio quality of which is to be measured by the UE 2,
15 on the basis of the measurement results of the radio qualities, the state of
the battery 204, and the load information. The control unit 103 notifies
the CC determined to be measured to the UE 2.
[0062]
The increase in the power consumption of the UE 2 can be
20 attempted to be suppressed by controlling a CC, the radio quality of which
is to be measured by the UE 2, in consideration not only of the state of the
battery 204 of the UE 2 but also of the network load.
Setting only some of CCs among CCs used in CA as objects to be
measured can result in the suppression of the interference to improve the
25 throughput of the entire wireless communication system 1 a.
[0063]
('Third Exemplary Embodiment)
Fig. 13 is a diagram illustrating the configuration of a wireless
comn1unication systen1 1 b according to a third exetnplary etnboditnent of
32
the present invention. The wireless communication system 1 b according
to the present exemplary embodiment is different from the wireless
communication system 1 a according to the second exemplary embodiment
in that in the former the eNB 30 is replaced with an eNB 31 and the
5 (H)eNB 13 is replaced with an eNB 32.
The eNBs 31 and 32 are wireless base stations forming cells. The
eNBs 31 and 32 wirelessly communicate with a UE 2 camping on the cells
formed by the eNBs 31 and 32, via Uu interfaces using the L TE scheme.
Assume herein that in the present exemplary embodiment, the UE 2 is
10 simultaneously connected to the eNBs 31 and 32, the eNB 31 serves as an
MeNB, the eNB 32 serves as an SeNB, and DC is performed. The eNB 31
will be referred to as an MeNB 3 1 and the eNB 3 2 will be referred to as an
SeNB 3 2 hereinafter.
15
[0064]
The configuration of the MeNB 31 will be described below. Since
the configuration of the SeNB 32 is the same as that of the MeNB 31, a.
description thereof will not be given.
Fig. 14 is a block diagram illustrating the configuration of the main
part of the MeNB 31.
20 The MeNB 31 illustrated in Fig. 14 includes a communication unit
25
401, a storage unit 402, and a control unit 403. The storage unit 402 is an
exemplary acquisition unit.
The communication unit 401 wirelessly communicates with the UE
2.
The storage unit 402 stores various types of information such as
load information.
The control unit 403 receives information indicating the
measurement results of the radio qualities and the state of a battery 204 of
the UE 2 fro111 the UE 2 via the conununication unit 401. The control unit
33
403 determines a signal, the radio quality of which is to be measured by the
UE 2, on the basis of the measurement results of the radio qualities and the
state of the battery 204 of the UE 2, indicated in the received information,
and the load information stored in the storage unit 402. The control unit
5 403 transmits a message indicating the signal determined to be measured to
the UE 2 via the communication unit 401.
10
[0065]
The operations of the MeNB 31 and the lJE 2 will be described
below.
The following description assumes that the MeNB 31 forms a
serving cell group (to be referred to as an MSG: Master Cell Group
hereinafter) 31 a, as illustrated in Fig. 15. Assume again that the SeNB 32
forms a serving cell group (to be referred to as an S~G: Secondary Cell
Group hereinafter) 32a. Assume further that the UE 2 is located within
15 both the coverage of the MSG 31 a and the coverage of the SSG 32a, has
established connection to the MeNB 31 and the SeNB 32, and performs DC.
The following description even assumes that a frequency a is used in the
MSG 31 a and a frequency p is used in the SSG 32a.
[0066]
20 Fig. 16 is a sequence chart illustrating the operations of the MeNB
3 1 and the UE 2.
First, the control unit 403 of the MeNB 31 requests a measurement
report to the UE 2 via the communication unit 401 (step S41 ). The
control unit 403 requests the measurement of the radio qualities of signals
25 transmitted in the MSG 31a and the SSG 32a. The storage unit 402
acquires and stores load information in advance. Since the details of load
information to be acquired and the method for acquiring load information
are the same as those in the first exemplary embodiment, a description
thereof will not be given.
34
[0067]
In response to the request for a measurement report from the MeNB
31, a control unit 205 of the UE 2 causes a measuring unit 202 to measure
the radio qualities of signals transmitted in the MSG 31 a and the SSG 32a
5 designated in the measurement report (step S42).
The control unit 205 causes the storage unit 203 to store the
measurement results (the radio qualities of signals transmitted in the MSG
31a and the SSG 32a) obtained by the measuring unit 202. The control
unit 205 further measures the state (remaining level) of the battery 204 and
10 causes the storage unit 203 to store the measurement result.
[0068]
The control unit 205 transmits information indicating the
measurement results of the radio qualities and the state (remaining level)
of the battery 204, stored in the storage unit 203, to the MeNB 31 via a
15 communication unit 201 as a measurement report (step S43 ). The control
unit 205 transmits information obtained by adding a parameter stated as
battery Level representing the percentage of the remaining level of the
battery 204 to the measurement report (MeasResults Information) of the
radio qualities, as in the first exemplary embodiment.
20 [0069]
Upon receiving the measurement report transmitted from the UE 2
via the communication unit 401, the control unit 403 of the MeNB 31
causes the storage unit 402 to store the received measurement report.
The control unit 403 determines whether to permit the UE 2 to use the SSG
25 32a, on the basis of the measurement report and the load information stored
in the storage unit 402. When, for example, the remaining level of the
battery 204 is low, or a few radio resources are available in the SSG 32a,
the control unit 403 determines not to permit the UE 2 to use the SSG 32a.
When, for exan1ple, the UE 2 performs DC and utilizes a service which
35
requires less pieces of data to be transmitted and received, such as VoL TE
(Voice over LTE), there is no problem even if both control data and user
data may be exchanged with the MeNB 31. This obviates the need to
transmit ACK/NACK to both the MeNB 31 and the SeNB 32 and measure
5 radio quality in the MSG 31a and the SSG 32a, thus the power consumption
of the UE 2 can be attempted to be reduced.
[0070]
When the control unit 403 determines not to permit the use of the
SSG 32a, the control unit 403 causes the storage unit 402 to store
10 information indicating that the use of the SSG 32a is not permitted and
information indicating that a signal having the frequency a transmitted in
the MSG 31 a has been determined as a signal, the radio quality of which is
to be measured by the UE 2. When the control unit 403 determines to
permit the use of the SSG 32a, the control unit 403 causes the storage unit
15 402 to store information indicating that a signal having the frequency a
transmitted in the MSG 31 a and a signal having the frequency ~
transmitted in the SSG 32a have been determined as signals, the radio
qualities of which are to be measured by the UE 2.
[0071]
20 The control unit 403 notifies the signals that have been determined
as objects, the radio qualities of which are to be measured by the UE 2, and
stored in the storage unit 3 02, via the communication unit 401 (step S45).
More specifically, when the control unit 403 determines to permit the use
of the SSG 32a, the control unit 403 transmits a message indicating a
25 signal having the frequency a transmitted in the MSG 31 a and a signal
having the frequency ~ transmitted in the SSG 32a, which are determined
as objects, the radio qualities of which are to be measured. When the
control unit 403 determines not to permit the use of the SSG 32a, the
control unit 403 transtnits a n1essage indicating a signal that has the
36
frequency a transmitted in the MSG 31 a and has been determined as an
object, the radio quality of which is to be measured, and indicating that the
use of the SSG 32a is not permitted. The following description assumes
that the control unit 403 has determined not to permit the use of the SSG
5 32a.
[0072]
Upon being notified the signal, the radio quality of which is to be
measured (the signal having the frequency a transmitted in the MSG 31 a),
via the communication unit 201, the control unit 205 causes the storage
10 unit 203 to store the notified signal. Since the control unit 205 is notified
that the use of the SSG 32a is not permitted, the control unit 205 causes the
storage unit 203 to store information indicating that the SSG 32a is not
used. The control unit 205 causes the communication unit 201 to release
connection with the SeNB 32 and causes the measuring unit 202 to measure
15 the radio quality of the signal having the frequency a transmitted in the
MSG 31a.
[0073]
In this manner, according to the present exemplary embodiment, the
MeNB 31 includes a communication unit 401 which communicates with the
20 UE 2, a storage unit 402 which acquires and stores load information for a
network, and a control unit 403. The control unit 403 receives
information indicating the measurement results of the radio qualities of the
MSG 31 a and the SSG 32a and the state of the battery 204 of the UE 2 from
the UE 2, and determines whether to permit the use of the SSG 32a, on the
25 basis of the measurement results of the radio qualities, the state of the
battery 204, and the load information. The control unit 103 determines a
signal, the radio quality of which is to be measured by the UE 2, in
accordance with the above-mentioned determination, and notifies the
signal determined to be measured to the UE 2.
37
[007 4]
The increase in the power consumption of the UE 2 can be
attempted to be suppressed by determining whether to permit the use of the
SSG 32a, in consideration not only of the state of the battery 204 of the UE
5 2 but also of the network load, and determining a signal, the radio quality
of which is to be measured by the UE 2, in accordance with the
above-mentioned determination.
Reducing the frequency bands of signals to be measured by the UE
2 can lead to the suppression of the interference to improve the throughput
10 of the entire wireless communication system 1 b.
[0075]
Although the HeNB 11 has been described by taking one which
acquires the measurement results of the radio qualities from the UE 2 as an
example in the first exemplary embodiment, the present invention is not
15 limited to this. As a modification, the HeNB 11 may include a measuring
unit 104 which ~easures the radio quality of the cell of each network, and
the control unit 103 may acquire the measurement results of the radio
qualities from the measuring unit 104, as illustrated in Fig. 17.
20
[0076]
Although the HeNB 11 has been described by taking one which
transmits a measurement request to the UE 2 which has established RRC
connection as an example in the first exemplary embodiment, the present
invention is not limited to this. As a modification, the HeNB 11 may use
information indicating the cell formed by the HeNB 11 to transmit a
25 measurement request even to a UE which camps on the cell and has not
established RRC connection.
ln the first exemplary embodiment, the HeNB 11 may determine
whether the WLAN cell 27a has been registered as a cell adjacent to the
cell formed by the HeNB 11, in accordance with the O&M (Operation &
38
Maintenace) procedure. The HeNB 11 may set a signal transmitted in the
WLAN cell 27a as an object to be measured when the WLAN cell 27a has
been registered, and may not set the signal transmitted in the WLAN cell
2 7 a as an object to be measured when the WLAN cell 2 7 a has not been
5 registered.
[0077]
Although an example in which an object, the radio quality of which
is to be measured by the UE 2, is determined in consideration of the load of
core networks and radio access networks has been used for description in
10 the first to third exemplary embodiments, the present invention is not
limited to this. As a modification, the load of interfaces between
wireless base stations, such as an X2 interface used during a handover, the
load of the CPU (Central Processing Unit) of a wireless base station
forming a cell which may serve as a handover destination, and the like may
15 be taken into consideration. When these loads are high, the rate of
handover success lowers. Therefore, the number of trials of handovers to
cells having low rates of handover success can be reduced by not setting
signals transmitted in cells formed by wireless base stations which require
interfaces to be connected or CPU s having high loads as objects, the radio
20 qualities of which are to be measured.
[0078]
As another modification, the type of service utilized may be set as
input to the evaluation function. For example, a signal in the GSM cell
24a or the UTRAN cell 20a may be used as an object to be measured when
25 a voice call is utilized, and a signal in the E-UTRAN cell 13 a or 14 b may
be used as an object to be measured when a streaming service for viewing
contents is utilized.
[0079]
As still another rnodification, the HeNB 11 may receive via an ltf-X
39
interface, data (for example, a policy) provided to the UE 2 by the ANDSF
18 and set the data as input to the evaluation function.
[0080]
In the second exemplary embodiment, when the remaining level of
5 the battery 204 has a margin, the number of CCs used by the UE 2 may be
increased. In the third exemplary embodiment, when the remaining level
of the battery 204 comes to have a margin after the determination of not to
permit the use of the SCG 32a, the use of the SCG 32a may be permitted.
The throughput can be improved by increasing the number of CCs used by
10 the UE 2 or permitting the use of the SCG 32a.
[0081]
Although an example in which a parameter stated as batteryLevel
representing the percentage of the remaining level of the battery 204 is
used as information on the state of the battery 204 has been used for
15 description in the first to third exemplary embodiments, the present
invention is not limited to this. As a modification, the absolute value
(for example, the discharge capacity (mAh) or the predicted value of the
endurance time) of the remaining level of the battery 204, the date of
manufacture, the type, the model number, or the like may be used as
20 information pertaining to the state of the battery 204. IMEISV
(International Mobile Equipment Identifier Software Version) including,
for example, the manufacturer, the model, the serial number, and the
software revision of the UE 2 may be set as input to the evaluation
function.
25 For example, even if the absolute value of the remaining level of
the battery 204 has a margin, when the model, the date of manufacture, the
serial number, or the software revision reveals that the UE 2 is an old
product and consumes much power, the remaining level of the battery 204
tnay be evaluated lower, or the like.
40
[0082]
Although the UE 2 has been described by taking one which reports
information pertaining to the state of the battery 204 together with the
measurement results of the radio qualities in response to the reception of a
5 measurement request from the wireless base station as an example in the
first to third exemplary embodiments, the present invention is not limited
to this. As a modification, the UE 2 may transmit information pertaining
to the state of the battery 204 in response to the trigger that the remaining
level of the battery 204 becomes equal to or higher than a predetermined
10 threshold or becomes equal to or lower than a predetermined threshold.
[0083]
Although an example in which information ("batteryLevel")
pertaining to the state of the battery 204 is notified from the UE 2 to the
wireless base station has been used for description in the first to third
15 exemplary embodiments, the present invention is not limited to this.
When the present invention is applied to a UTRAN, a parameter (an area
marked with a dotted frame in Fig. 18) stated as batteryLevel may be added
to a message defined in 3 G P P T S 2 5 . 3 3 1 v 12. 1. 0, as i 11 us tr ate d in Fig. 1 8 .
[0084]
20 Although the first exemplary embodiment has been described in
25
conjunction with L TE, the present invention may be applied to other
networks such as a UTRAN, a GSM, a WLAN, and a CDMA (Code Division
Multiple Access) 2000.
[0085]
In the first to third exemplary embodiments, when MIMO (Multi
input Multi Output) is used, the number of antennas used may be decreased
in accordance with output from the evaluation function. This can reduce
the power consumption of the UE 2.
[008G]
41
A technique called 3D beamforming is under study in
L TE-Advanced. In this technique, interference between cells is reduced
by horizontal and vertical beamforming and another beam is formed
between the UEs 2 in the same cell. In the first to third exemplary
5 embodiments, when 3D beamforming is used, the shape of a beam to be
generated may be controlled in accordance with the output from the
evaluation function. For example, the beam may be shaped thick when
the remaining level of the battery 204 is high, and the beam may be shaped
small when the remaining level of the battery 204 is low. This can reduce
10 the power consumption of the UE 2.
[0087]
Although the UE 2 has been described by taking one which releases
connection to the SeNB 3 2 and continues communication with the MeNB
31 as an example in the third exemplary embodiment, the present invention
15 is not limited to this. As a modification, the UE 2 may release connection
between the MeNB 31 and the UE 2 and continue connection to the SeNB
32.
[0088]
Although the UE 2 has been described by taking one which
20 performs processing according to a message for notifying a signal to be
measured, upon receiving the message, as an example in the first to third
exemplary embodiments, the present invention is not limited to this. For
example, the wireless base station incorporates a timer into a message,
then the UE 2 receives the message, thereafter may start the timer, and
25 when the timer terminates, the UE 2 may perform processing according to
the message. Further, the wireless base station incorporates a timer and
the threshold of a counter into a message. The UE 2 may repeat a process
of starting the timer after the reception of the message, incrementing the
value of the counter when the timer terminates, performing processing
42
according to the message, and after performing the processing, restarting
the timer, until the value of the counter exceeds the threshold.
The first to third exemplary embodiments may be combined as
appropriate.
5 [0089]
The method conducted in the wireless base station and the mobile
station (UE) according to the present invention may be applied to a
program to be executed by a computer. The program may even be stored
on a storage medium or provided to the outside via a network.
10 [0090]
15
Part or all of the above-described exemplary embodiments may be
described as in the following supplementary notes, but they are not limited
thereto.
[0091]
(Supplementary Note 1)
A wireless base station comprising:
a communication unit which communicates with a mobile station
which measures radio quality of a signal transmitted in each of a plurality
of cells;
20 an acquisition unit which acquires load information related to a
load of a network including a wireless base station forming the cell; and
a control unit which receives information indicating a measurement
result of the radio quality of the signal transmitted in each of the plurality
of cells and a state of a battery of the mobile station, from the mobile
25 station via the communication unit, determines a signal, radio quality of
which is to be measured by the mobile station, on the basis of the
measurement results of the radio qualities and the state of the battery of ;
the mobile station, indicated in the received information, and the load
information acquired by the acquisition unit, and notifies the signal
5
43
determined to be measured to the mobile station via the communication
unit.
[0092]
(Supplementary Note 2)
The wireless base station according to supplementary note 1,
wherein
the signal transmitted in each of the plurality of cells includes
signals having different communication schemes, and
the control unit determines a signal, radio quality of which is to be
10 measured by the mobile station, and transmits a message indicating at least
15
one of a communication scheme of the signal to be measured and a
frequency band of the signal to be measured to the mobile station via the
communication unit.
[0093]
(Supplementary Note 3)
The wireless base station according to supplementary note 1,
wherein
the signal transmitted in each of the plurality of cells includes
signals having a predetermined frequency band including at least one
20 component carrier serving as a unit frequency band, and
the control unit determines the component carrier, radio quality of
which is to be measured by the mobile station, and transmits a message
indicating the component carrier to be measured to the mobile station via
the communication unit.
25 [0094]
(Supplementary Note 4)
The wireless base station according to supplementary note 1 ~
wherein
the signal transmitted in each of the plurality of cells includes a
44
signal from each of the plurality of cells connected to the mobile station,
and
the control unit determines a signal, radio quality of which is to be
measured by the mobile station, and transmits a message indicating at least
5 one of a frequency band of the signal to be measured and a feature that
connection to a cell in which a signal that is not to be measured is
transmitted is to be released, to the mobile station via the communication
unit.
[0095]
10
station;
(Supplementary Note 5)
A mobile station comprising:
a battery;
a communication unit which communicates with a wireless base
15 a measuring unit which measures radio quality of a signal
transmitted in each of a plurality of cells; and
a control unit which transmits information indicating a
measurement result of the radio quality of the signal transmitted in each of
the plurality of cells, obtained by the measuring unit, and a state of the
20 battery of the mobile station, to the wireless base station via the
communication unit, and, upon being notified a signal, the radio quality of
which is to be measured, from the wireless base station via the
communication unit, causes the measuring unit to measure the radio quality
of the notified signal.
25 [0096]
(Supplementary Note 6)
The mobile station according to supplementary note 5, wherein
the signal transmitted in each of the plurality of cells includes
signals having different communication schemes, and
45
upon receiving a message indicating at least one of a
communication scheme of a signal to be measured and a frequency band of
the signal to be measured from the wireless base station via the
communication unit, the control unit causes the measuring unit to measure
5 radio quality of a signal having the communication scheme or the
frequency band indicated in the message.
10
[0097]
(Supplementary Note 7)
The mobile station according to supplementary note 5, wherein
the signal transmitted in each of the plurality of cells includes
signals having a predetermined frequency band including at least one
component carrier serving as a unit frequency band, and
upon receiving a message indicating a component carrier to be
measured from the wireless base station via the communication unit, the
15 control unit causes the measuring unit to measure radio quality of the
20
component carrier indicated in the message.
[0098]
(Supplementary Note 8)
The mobile station according to supplementary note 5, wherein
the signal transmitted in each of the plurality of cells includes a
signal from each of the plurality of cells connected to the mobile station,
and
upon receiving a message indicating at least one of a frequency
band of the signal to be measured and a feature that connection to a cell in
25 which a signal that is not to be measured is transmitted is to be cut off from
the wireless base station via the communication unit, the control unit
causes the measuring unit to measure radio quality of the signal indicated
in the rnessage and causes the con1munication unit to r~l~as~ the
connection to the cell in which the signal that is not to be measured is
5
46
transmitted.
[0099]
station,
(Supplementary Note 9)
A wireless communication system comprising:
a mobile station; and
a wireless base station which communicates with the mobile
wherein the mobile station measures radio quality of a signal
transmitted in each of a plurality of cells and transmits information
10 indicating a measurement result of the radio quality of the signal
transmitted in each of the plurality of cells and a state of a battery of the
mobile station to the wireless base station,
the wireless base station acquires load information related to a load
of a network including a wireless base station forming the cell, determines
15 a signal, radio quality of which is to be measured by the mobile station, on
the basis of the measurement results of the radio qualities and the state of
the battery of the mobile station, transmitted from the mobile station, and
the acquired load information, and notifies the signal determined to be
measured to the mobile station, and
20 the mobile station measures radio quality of the signal notified
from the wireless base station.
[0 1 00]
(Supplementary Note 1 0)
The wireless communication system according to supplementary
25 note 9, wherein
the signal transmitted in each of the plurality of cells includes
signals having different communication schemes,
the wire 1 ess base s tatiuu d ~;: tennines a signal, radio q uali ly of which
is to be measured by the mobile station, and transmits a message indicating
47
at least one of a communication scheme of the signal to be measured and a
frequency band of the signal to be measured to the mobile station, and
upon receiving the message indicating the at least one of the
communication scheme of the signal to be measured and the frequency
5 band of the signal to be measured from the wireless base station, the
mobile station measures radio quality of the signal having the
communication scheme or the frequency band indicated in the message.
[0101]
10
(Supplementary Note 11)
The wireless communication system according to supplementary
note 9, wherein
the signal transmitted in each of the plurality of cells includes
signals having a predetermined frequency band including at least one
component carrier serving as a unit frequency band,
15 the wireless base station determines a component carrier, radio
quality of which is to be measured by the mobile station, and transmits a
message indicating the component carrier to be measured to the mobile
station, and
upon receiving the message indicating the component carrier to be
20 measured from the wireless base station, the mobile station measures radio
quality of the component carrier indicated in the message.
[0102]
(Supplementary Note 12)
The wireless communication system according to supplementary
25 note 9, wherein
the signal transmitted in each of the plurality of cells includes a
signal from each of the plurality of cells connected to the mobile station,
the wireless base station determines a signal, radio quality of which
is to be measured by the mobile station, and transmits a message indicating
48
at least one of a frequency band of the signal to be measured and a feature
that connection to a cell in which a signal that is not to be measured is
transmitted is to be released, and
upon receiving the message indicating the at least one of the
5 frequency band of the signal to be measured and a feature that the
connection to the cell in which the signal that is not to be measured is
transmitted is to be cut off from the wireless base station, the mobile
station measures radio quality of the signal indicated in the message and
releases the connection to the cell in which the signal that is not to be
10 measured is transmitted.
[0 103]
(Supplementary Note 13)
A control method for a wireless base station, the method
compns1ng:
15 communicating with a mobile station which measures radio quality
of a signal transmitted in each of a plurality of cells;
acquiring load information related to a load of a network including
a wireless base station forming the cell; and
receiving information indicating a measurement result of the radio
20 quality of the signal transmitted in each of the plurality of cells and a state
of a battery of the mobile station, from the mobile station, determining a
signal, radio quality of which is to be measured by the mobile station, on
the basis of the measurement results of the radio qualities and the state of
the battery of the mobile station, indicated in the received information, and
25 the load information acquired by the acquisition unit, and notifying the
signal determined to be measured to the mobile station.
L u 104 J
(S upplen1entary Note 14)
A program for causing a computer within a wireless base station to
49
perform the processes of:
communicating with a mobile station which measures radio quality
of a signal transmitted in each of a plurality of cells;
acquiring load information related to a load of a network including
5 a wireless base station forming the cell; and
receiving information indicating a measurement result of the radio
quality of the signal transmitted in each of the plurality of cells and a state
of a battery of the mobile station, from the mobile station, determining a
signal, radio quality of which is to be measured by the mobile station, on
10 the basis of the measurement results of the radio qualities and the state of
the battery of the mobile station, indicated in the received information, and
the load information acquired by the acquisition unit, and notifying the
signal determined to be measured to the mobile station.
15
[0 1 05]
Although the present invention has been described above with
reference to exemplary embodiments, the present invention is not limited
to the above-described exemplary embodiments. Various changes which
would be understood by those skilled in the art may be made to the
configurations or details of the present invention within the scope of the
20 present invention. This application claims priority based on Japanese
Patent A p p 1 i cation No. 2 0 14- 1 9 9 7 3 3 fi 1 e d on September 3 0, 2 0 14, the
25
disclosure of which is incorporated herein in its entirety.
Reference signs List

[CLAIMS]
(Claim 1)
51
A wireless base station comprising:
a communication unit configured to communicate with a mobile
5 station which measures radio quality of a signal transmitted in each of a
plurality of cells;
an acquisition unit configured to acquire load information related to
a load of a network including a wireless base station forming the cell; and
a control unit configured to receive information indicating a
10 measurement result of the radio quality of the signal transmitted in each of
the plurality of cells and a state of a battery of the mobile station, from the
mobile station via the communication unit,
determine a signal, radio quality of which is to be meas~red by the mobile
station, based on the measurement results of the radio qualities and the
15 state of the battery of the mobile station, indicated in the information
received, and the load information acquired by the acquisition unit, and
notify the signal determined to be measured to the mobile station via the
communication unit.
20 (Claim 2)
The wireless base station according to claim 1,
wherein the signal transmitted in each of the plurality of cells includes
signals having different communication schemes, and
wherein the control unit determines a signal, radio quality of which
25 is to be measured by the mobile station, and
transmits, to the mobile station via the communication unit, a message
indicating at least one of a communication scheme of the signal to be
tncasurcd and a frequency band of the signal to b~ n1~asur~d.
52
(Claim 3)
The wireless base station according to claim 1,
wherein the signal transmitted in each of the plurality of cells
includes signals having a predetermined frequency band including at least
5 one component carrier serving as a unit frequency band, and
10
wherein the control unit determines the component carrier, radio
quality of which is to be measured by the mobile station, and transmits a
message indicating the component carrier to be measured to the mobile
station via the communication unit.
(Claim 4)
The wireless base station according to claim 1,
wherein the signal transmitted in each of the plurality of cells includes a
signal from each of the plurality of cells connected to the mobile station,
15 and
wherein the control unit determines a signal, radio quality of which
is to be measured by the mobile station, and
transmits, to the mobile station via the communication unit, a message
indicating at least one of a frequency band of the signal to be measured and
20 information that connection to a cell in which a signal that is not to be
measured is transmitted is to be released.
25
(Claim 5)
A mobile station comprising:
a battery;
a communication unit configured to communicate with a wireless
base station;
a measuring unit configured to measure radio q.uality of a signal
transmitted in each of a plurality of cells; and
53
a control unit configured to transmit, to the .wireless base station
via the communication unit, information indicating a measurement result
of the radio quality of the signal transmitted in each of the plurality of
cells, obtained by the measuring unit, and a state of the battery of the
5 mobile station, and,
10
upon being notified a signal, the radio quality of which is to be measured,
from the wireless base station via the communication unit, causes the
measuring unit to measure the radio quality of the notified signal.
(Claim 6)
The mobile station according to claim 5,
wherein the signal transmitted in each of the plurality of cells includes
signals having different communication schemes, and
wherein, upon receiving a message indicating at least one of a
15 communication scheme of a signal to be measured and a frequency band of
20
the signal to be measured from the wireless base station via the
communication unit, the control unit causes the measuring unit to measure
radio quality of a signal having the communication scheme or the
frequency band indicated in the message.
(Claim 7)
The mobile station according to claim 5,
wherein the signal transmitted in each of the plurality of cells includes
signals having a predetermined frequency band including at least one
25 component carrier serving as a unit frequency band, and
wherein, upon receiving a message indicating a component carrier
to be measured from the wireless base station via the communication unit,
the control unit causes the measuring unit to measure radio quality of the
con1ponent carrier indicated in the tnessage.
54
(Claim 8)
A wireless communication system comprising:
a mobile station; and
5 a wireless base station which communicates with the mobile station,
wherein the mobile station
measures radio quality of a signal transmitted in each of a plurality of cells
and
transmits information indicating a measurement result of the radio quality
10 of the signal transmitted in each of the plurality of cells and a state of a
battery of the mobile station to the wireless base station,
wherein the wireless base station
acquires load information related to a load of a network including a
wireless base station forming the cell,
15 determines a signal, radio quality of which is to be measured by the mobile
station, based on the measurement results of the radio qualities and the
state of the battery of the mobile station, transmitted from the mobile
station, and the acquired load information, and
notifies the signal determined to be measured to the mobile station, and
20 wherein the mobile station measures radio quality of the signal
notified from the wireless base station.
(Claim 9)
A control method for a wireless base station, the method
25 compnstng:
communicating with a mobile station which measures radio quality
of a signal transmitted in each of a plurality of cells;
acquiring load information related to a load of a network including
a wireless base station forming the cell;
55
receiving information indicating a measurement result of the radio
quality of the signal transmitted in each of the plurality of cells and a state
of a battery of the mobile station, from the mobile station;
determining a signal, radio quality of which is to be measured by the
5 mobile station, based on the measurement results of the radio qualities and
the state of the battery of the mobile station, indicated in the received
information, and the load information acquired by the acquisition unit; and
notifying the signal determined to be measured to the mobile station.
10 (Claim 1 0)
A computer readable recording medium storing a program for
causing a computer within a wireless base station to perform a method, the
method comprising:
communicating with a mobile station which measures radio quality
15 of a signal transmitted in each of a plurality of cells;
acquiring load information related to a load of a network including
a wireless base station forming the cell;
receiving information indicating a measurement result of the radio
quality of the signal transmitted in each of the plurality of cells and a state
20 of a battery of the mobile station, from the mobile station,
determining a signal, radio quality of which is to be measured by the
mobile station, based on the measurement results of the radio qualities and
the state of the battery of the mobile station, indicated in the received
information, and the load information acquired by the acquisition unit; and
25 notifying the signal determined to be measured to the mobile station.