U.S. patent number 9,271,161 [Application Number 13/699,208] was granted by the patent office on 2016-02-23 for mobile station, radio base station and communication control method.
This patent grant is currently assigned to NTT DOCOMO, INC.. The grantee listed for this patent is Hiroyuki Ishii, Mikio Iwamura, Anil Umesh. Invention is credited to Hiroyuki Ishii, Mikio Iwamura, Anil Umesh.
United States Patent |
9,271,161 |
Ishii , et al. |
February 23, 2016 |
Mobile station, radio base station and communication control
method
Abstract
A mobile station UE of the present invention is a mobile station
that communicates with a radio base station using equal to or
greater than two carriers, wherein the equal to or greater than two
carriers include a first carrier and a second carrier, the mobile
station including: a first communicating unit configured to perform
communication with the first carrier; and a second carrier
measuring unit configured to perform measurement of the second
carrier, wherein, in a case where a measurement gap for measuring
the second carrier is set, the first communicating unit is
configured to perform communication with the first carrier without
considering the measurement gap when the second carrier is
activated, and not to perform communication with the first carrier
in the measurement gap when the second carrier is not
activated.
Inventors: |
Ishii; Hiroyuki (Tokyo,
JP), Iwamura; Mikio (Tokyo, JP), Umesh;
Anil (Tokyo, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Ishii; Hiroyuki
Iwamura; Mikio
Umesh; Anil |
Tokyo
Tokyo
Tokyo |
N/A
N/A
N/A |
JP
JP
JP |
|
|
Assignee: |
NTT DOCOMO, INC. (Tokyo,
JP)
|
Family
ID: |
45003762 |
Appl.
No.: |
13/699,208 |
Filed: |
May 6, 2011 |
PCT
Filed: |
May 06, 2011 |
PCT No.: |
PCT/JP2011/060607 |
371(c)(1),(2),(4) Date: |
January 18, 2013 |
PCT
Pub. No.: |
WO2011/148770 |
PCT
Pub. Date: |
December 01, 2011 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20130107743 A1 |
May 2, 2013 |
|
Foreign Application Priority Data
|
|
|
|
|
May 24, 2010 [JP] |
|
|
2010-118834 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L
5/0098 (20130101); H04W 24/00 (20130101); H04W
72/02 (20130101); H04L 5/001 (20130101); H04L
5/0091 (20130101); H04W 28/06 (20130101); H04W
72/0453 (20130101); H04W 48/16 (20130101); Y02D
30/70 (20200801); H04W 76/28 (20180201) |
Current International
Class: |
G01R
31/08 (20060101); H04W 24/00 (20090101); H04L
5/00 (20060101); H04W 72/02 (20090101); H04W
28/06 (20090101); H04W 76/04 (20090101); H04W
72/04 (20090101); H04W 48/16 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
International Search Report issued in PCT/JP2011/060607 mailed Aug.
9, 2011 (2 pages). cited by applicant .
3GPP TR 36.913 V8.0.1; "3rd Generation Partnership Project;
Technical Specification Group Radio Access Network; Requirements
for further advancements for Evolved Universal Terrestrial Radio
Access (E-UTRA) (LTE-Advanced) (Release 8)"; Mar. 2009 (15 pages).
cited by applicant .
3GPP TS 36.331 V8.8.0; "3rd Generation Partnership Project;
Technical Specification Group Radio Access Network; Evolved
Universal Terrestrial Radio Access (E-UTRA) Radio Resource Control
(RRC); Protocol specification (Release 8)"; Dec. 2009 (211 pages).
cited by applicant .
3GPP TS 36.213 V8.8.0; "3rd Generation Partnership Project;
Technical Specification Group Radio Access Network; Evolved
Universal Terrestrial Radio Access (E-UTRA); Physical layer
procedures (Release 8)"; Sep. 2009 (77 pages). cited by applicant
.
3GPP TS 36.133 V8.7.0; "3rd Generation Partnership Project;
Technical Specification Group Radio Access Network; Evolved
Universal Terrestrial Radio Access (E-UTRA); Requirements for
support of radio resource management (Release 8)"; Sep. 2009 (317
pages). cited by applicant .
Office Action issued in counterpart Korean application No.
10-2012-7033400, mailed Mar. 20, 2014 (8 pages). cited by applicant
.
NTT DoCoMo, "Measurement gap control in CA"; 3GPP TSG-RAN WG2
Meeting #69bis, R2-102499; Beijing, China; Apr. 12-Apr. 16, 2010 (3
pages). cited by applicant .
Office Action issued in corresponding Chinese Application No.
201180035627.5, mailed Aug. 29, 2014 (16 pages). cited by applicant
.
Notice of Decision of Rejection issued in corresponding Korean
Application No. 10-2012-7033400, mailed Oct. 14, 2014 (6 pages).
cited by applicant .
Partial European Search Report issued in corresponding European
Application No. 11786470.2 dated Jan. 9, 2015 (8 pages). cited by
applicant .
Huawei, "Measurements on deactivated CC", 3GPP Draft; R2-101021
Measurement on Deactivated CC, 3rd Generation Partnership Project
(3GPP), Mobile Competence Centre; 650, Route Des Lucioles; F-06921
Sophia-Antipolis Cedex; France, vol. RAN WG2, No. San Francisco,
USA; dated Feb. 22-Feb. 26, 2010 (6 pages). cited by applicant
.
Ericsson et al., "Summary of the email discussion [68#23] LTE: CC
activation/deactivation", 3GPP Draft; R2-100079 Summary of the
Email Discussion 68-23 LTE CC Activation Deactivation, 3rd
Generation Partnership Project (3GPP), Mobile Competence Centre;
650, Route Des Lucioles; F-06921 Sophia-Antipolis Cedex; France,
vol. RAN WG2, No. Valencia, Spain; dated Jan. 18-Jan. 22, 2010 (17
pages). cited by applicant .
Extended European Search Report issued in corresponding European
Application No. 11786470.2 dated Apr. 29, 2015 (11 pages). cited by
applicant .
Office Action mailed Feb. 2, 2015, in corresponding Korean Patent
Application No. 10-2012-7033400 (with translation) (5 pages). cited
by applicant .
Office Action issued in corresponding Chinese Application No.
201180035627.5 dated Feb. 2, 2015, and English translation thereof
(15 pages). cited by applicant .
Third Office Action in counterpart Chinese Patent Application No.
201180035627.5, dated Jun. 30, 2015 (13 pages). cited by
applicant.
|
Primary Examiner: Oveissi; David
Attorney, Agent or Firm: Osha Liang LLP
Claims
The invention claimed is:
1. A mobile station that communicates with a radio base station
using equal to or greater than two carriers, wherein the equal to
or greater than two carriers include a first carrier and a second
carrier, the mobile station comprising: a first communicating unit
configured to perform communication with the first carrier and the
second carrier using a bandwidth; and a second carrier measuring
unit configured to perform measurement of the second carrier,
wherein, in a case where a measurement gap for measuring the second
carrier is set in the first carrier, the first communicating unit
is configured to perform, without changing the bandwidth,
communication with the first carrier and the second carrier without
considering the measurement gap when the second carrier is
activated, and not to perform communication with the first carrier,
by changing the bandwidth, in the measurement gap when the second
carrier is not activated, and wherein the second carrier measuring
unit is configured to perform measurement of received power of the
second carrier in the measurement gap when the second carrier is
not activated.
2. The mobile station as claimed in claim 1, wherein, the second
carrier measuring unit is configured to perform measurement of the
second carrier without using the measurement gap when the second
carrier is activated, and to perform measurement of the second
carrier using the measurement gap when the second carrier is not
activated.
3. The mobile station as claimed in claim 1, wherein the
measurement gap is a time section provided to measure a carrier of
a different frequency or a carrier of a different radio
communication system.
4. The mobile station as claimed in claim 1, wherein the first
carrier and the second carrier belong to the same frequency
band.
5. A communication control method in a mobile station that
communicates with a radio base station using equal to or greater
than two carriers, wherein the equal to or greater than two
carriers include a first carrier and a second carrier, the
communication control method comprising: a first step of performing
communication with the first carrier and the second carrier using a
bandwidth; and a second step of performing measurement of the
second carrier, wherein, in the first step, in a case where a
measurement gap for measuring the second carrier is set in the
first carrier, when the second carrier is activated, the mobile
station performs, without changing the bandwidth, communication
with the first carrier and the second carrier without considering
the measurement gap, and when the second carrier is not activated,
the mobile station does not perform communication with the first
carrier, by changing the bandwidth, in the measurement gap, and
wherein the performing measurement performs measurement of received
power of the second carrier in the measurement gap when the second
carrier is not activated.
Description
TECHNICAL FIELD
The present invention relates to a mobile station, a radio base
station, and a communication control method.
BACKGROUND ART
As a successor of a WCDMA (Wideband Code Division Multiplexing
Access) system, an HSDPA (High-Speed Downlink Packet Access)
system, and an HSUPA (High-Speed Uplink Packet Access) system, an
LTE (Long Term Evolution) system has been considered and
standardized by 3GPP (The 3rd Generation Partnership Project),
which is a standardization organization of WCDMA.
Furthermore, as a successor of the LTE system, an LTE-advanced
system is under consideration by 3GPP. The requirements for the
LTE-advanced system are summarized in the non-patent document
1.
As one of the requirements in the LTE-advanced system, an agreement
is reached that carrier aggregation is applied. When carrier
aggregation is applied, a mobile station UE can receive downlink
signals simultaneously using plural carriers or transmit uplink
signals simultaneously using plural carriers. Each carrier used in
carrier aggregation is referred to as a "component carrier".
The plural component carriers are categorized into a primary
component carrier as a main carrier and one or more secondary
component carriers other than the primary component carrier.
When a mobile station UE performs communications always using the
primary component carrier and the secondary component carriers, a
problem arises that power consumption becomes higher in proportion
to the number of component carriers. As used herein, communicating
using the primary component carrier and the secondary component
carriers includes usual data transmission and reception, cell
search or measurement on the respective carriers, and radio link
monitoring.
For example, the cell search includes establishing synchronization
in downlink using downlink synchronization signals in a serving
cell and an adjacent cell. Since cell search is the processing for
detecting a destination cell while a mobile station UE is moving,
the mobile station UE periodically needs to perform cell search.
For example, the measurement includes measuring received power
(more specifically, RSRP (Reference Signal Received Power) or the
like) of reference signals in a serving cell and an adjacent cell.
It should be noted that the combined processing of cell search and
measurement may be referred to as "measurement". The radio link
monitoring includes measuring radio quality (more specifically, SIR
(Signal-to-Interference Ratio)) of reference signals in a serving
cell, determining whether the SIR is above a predetermined
threshold, and determining that the serving cell is in
out-of-synchronization when the SIR is below the predetermined
threshold. The processing associated with cell search, measurement,
and radio link monitoring and their performance definitions are
described in non-patent documents 2 and 3, for example.
In order to address the problem of power consumption, it is
considered that control of activation/de-activation is applied in
the secondary component carrier, for example. For example, on a
secondary component carrier in a de-activation state, the mobile
station UE does not perform usual data transmission and reception
and reduces the frequencies of cell search, measurement, and radio
link monitoring, thereby saving the battery. The processing of
de-activation on a secondary component carrier is performed when
the amount of data to be communicated is small, for example.
In addition, in the LTE system, a measurement gap is defined in
order to perform measurement on a carrier with a different
frequency or a carrier for a different radio communication system
(non-patent document 4). The length of the measurement gap is
defined as 6 ms and its periodicity is defined as 40 ms or 80 ms,
for example. During the measurement gap, the mobile station UE
suspends communications in a serving cell and performs measurement
of a carrier of a different frequency or a carrier of a different
radio communication system. In this case, communication with the
serving cell is stopped, throughput of communication with the
serving cell deteriorates.
PRIOR ART DOCUMENTS
[Non-patent document 1] 3GPP TR36.913 (V8.0.1) [Non-patent document
2] 3GPP TS36.213 V8.8.0 (2009-09) [Non-patent document 3] 3GPP
TS36.133 V8.7.0 (2009-09) [Non-patent document 4] 3GPP TS36.331
V8.8.0 (2009-12)
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
As described above, when carrier aggregation is applied, it is
considered that deactivation is applied in a secondary component
carrier.
In this case, as shown in FIG. 1, a mobile station UE performs
communications only on a primary component carrier in an ordinary
state (section A1). Only when the mobile station UE performs cell
search, measurement, or radio link monitoring (section A2) on a
secondary component channel, the mobile station UE performs
communications on both of the primary component carrier and the
secondary component carrier.
However, as shown in FIGS. 2 and 3, the mobile station UE needs to
change the center frequency of the receiver between the case where
the mobile station UE performs communications only with the primary
component carrier and the case where the mobile station UE performs
communications with both of the primary component carrier and the
secondary component carrier, for example. As a result, at the time
of the change between the case where the mobile station UE performs
communications only on the primary component carrier and the case
where the mobile station UE performs communications on both of the
primary component carrier and the secondary component carrier, a
problem arises that the mobile station UE cannot transmit and
receive data on the primary component carrier. For example, the
state in which the mobile station UE cannot transmit and receive
data may include a state in which data to be transmitted and
received are lost.
In other words, when the mobile station UE receives plural
component carriers using a single receiver, the change of the
center frequency of the receiver occurs when the number of
component carriers to be received changes, for example. As a
result, the mobile station UE cannot transmit and receive data at
the time of the change.
Since the time when the mobile station UE performs cell search,
measurement, or radio link monitoring typically depends on the
implementation of the mobile station UE, the radio base station eNB
cannot recognize when data are lost.
In order to solve the above-mentioned problem, it may be considered
to set the above-mentioned measurement gap in the primary component
carrier and to perform measurement of the secondary component
carrier in the measurement gap. However, in this case, since
communication using the primary component carrier cannot be
performed in the measurement gap, there is a problem in that
throughput of the primary component carrier deteriorates.
The present invention is contrived in view of the problem as
described above, and an object of the present invention is to
provide a mobile station, a radio base station, and a communication
control method for making a system more efficient and achieving
stability of connections, by saving a battery when carrier
aggregation is applied while appropriately performing cell search,
measurement, or the like on each component carrier.
Means for Solving the Problem
A mobile station of the present invention is a mobile station that
communicates with a radio base station using equal to or greater
than two carriers, wherein the equal to or greater than two
carriers include a first carrier and a second carrier, the mobile
station including:
a first communicating unit configured to perform communication with
the first carrier; and
a second carrier measuring unit configured to perform measurement
of the second carrier,
wherein, in a case where a measurement gap for measuring the second
carrier is set, the first communicating unit is configured
to perform communication with the first carrier without considering
the measurement gap when the second carrier is activated, and
not to perform communication with the first carrier in the
measurement gap when the second carrier is not activated.
A communication control method of the present invention is a
communication control method in a mobile station that communicates
with a radio base station using equal to or greater than two
carriers, wherein the equal to or greater than two carriers include
a first carrier and a second carrier, the communication control
method including:
a first step of performing communication with the first carrier;
and
a second step of performing measurement of the second carrier,
wherein, in the first step, in a case where a measurement gap for
measuring the second carrier is set, when the second carrier is
activated, the mobile station performs communication with the first
carrier without considering the measurement gap, and when the
second carrier is not activated, the mobile station does not
perform communication with the first carrier in the measurement
gap.
A radio base station of the present invention is a radio base
station that communicates with a mobile station using equal to or
greater than two carriers, wherein the equal to or greater than two
carriers include a first carrier and a second carrier, the radio
base station including:
a first communicating unit configured to perform communication with
the first carrier,
wherein, in a case where a measurement gap for measuring the second
carrier is set, the first communicating unit is configured
to perform communication with the first carrier without
consideration of the measurement gap when the second carrier is
activated, and
not to perform communication with the first carrier in the
measurement gap when the second carrier is not activated.
A communication control method of the present invention is a
communication control method in a radio base station that
communicates with a mobile station using equal to or greater than
two carriers, wherein the equal to or greater than two carriers
include a first carrier and a second carrier, the communication
control method including:
a first step of performing communication with the first
carrier,
wherein, in a case where a measurement gap for measuring the second
carrier is set, when the second carrier is activated, the radio
base station performs communication with the first carrier without
consideration of the measurement gap, and when the second carrier
is not activated, the radio base station does not perform
communication with the first carrier in the measurement gap.
Effect of the Present Invention
According to the present invention, it becomes possible to provide
a mobile station, a radio base station, and a communication control
method for making a system more efficient and achieving stability
of connections, by saving a battery when carrier aggregation is
applied while appropriately performing cell search, measurement, or
the like on each component carrier.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram for explaining operation for measuring a
secondary component carrier in a de-activated state in a
conventional mobile communication system;
FIG. 2 is a diagram showing a center frequency of a receiver when
both of a primary component carrier and a secondary component
carrier are received;
FIG. 3 is a diagram showing a center frequency of a receiver when
only a primary component carrier is received;
FIG. 4 is a diagram for explaining component carriers in a mobile
communication system in accordance with an embodiment of the
present invention;
FIG. 5 is a diagram for explaining operations of a mobile station
and a radio base station in accordance with an embodiment of the
present invention (in a case where one gap section is used);
FIG. 6 is a diagram for explaining operations of a mobile station
and a radio base station in accordance with an embodiment of the
present invention (in a case where two gap sections are used);
FIG. 7 is a diagram for explaining a measurement gap formed by two
gap sections in accordance with an embodiment of the present
invention;
FIG. 8 is a diagram for explaining a measurement gap formed by two
gap sections in accordance with an embodiment of the present
invention;
FIG. 9 is a diagram for explaining a measurement gap formed by two
gap sections in accordance with an embodiment of the present
invention;
FIG. 10 is a block diagram of a mobile station in accordance with
an embodiment of the present invention;
FIG. 11 is a block diagram of a radio base station in accordance
with an embodiment of the present invention;
FIG. 12 is a flowchart of a communication control method in a
mobile station in accordance with an embodiment of the present
invention;
FIG. 13 is a flowchart of a communication control method in a radio
base station in accordance with an embodiment of the present
invention;
FIG. 14 is a diagram for explaining a measurement gap formed by two
gap sections in accordance with an embodiment of the present
invention;
FIG. 15 is a diagram showing a communication control method in a
mobile station UE; and
FIG. 16 is a diagram showing a communication control method in a
radio base station eNB.
EMBODIMENTS FOR CARRYING OUT THE INVENTION
Configuration of a Mobile Communication System in Accordance with a
First Embodiment of the Present Invention
A mobile communication system in accordance with a first embodiment
of the present invention is described below with reference to the
accompanying drawings. Throughout the figures for illustrating the
embodiments of the present invention, the same reference numerals
are used for the same or equivalent elements and their repeated
descriptions may be omitted.
For example, the mobile communication system in accordance with
this embodiment is an LTE-advanced system. In other words, the
mobile communication system in accordance with this embodiment
includes a radio base station eNB and a mobile station UE for
communicating with the radio base station eNB, and the radio base
station eNB and the mobile station UE perform communications
according to the LTE-Advanced scheme. The mobile station UE may be
also referred to as a user apparatus.
Communication channels used in the mobile communication system in
accordance with this embodiment are described below.
In the mobile communication system in accordance with this
embodiment, a PDSCH (Physical Downlink Shared Channel) shared by
mobile stations UE and a PDCCH (Physical Downlink Control Channel)
are used in downlink.
User data (i.e. typical data signals) are transmitted via the
PDSCH.
Control signals such as an ID of a mobile station UE for performing
communications using the PDSCH and transport format information of
user data (i.e. downlink scheduling information) as well as an ID
of a mobile station UE for performing communications using a PUSCH
(Physical Uplink Shared Channel) and transport format information
of user data (i.e. uplink scheduling grant) are transmitted via the
PDCCH.
The PDCCH may be also referred to as a "Downlink L1/L2 Control
Channel". The downlink scheduling information and the uplink
scheduling grant may be collectively referred to as "downlink
control information (DCI)".
In downlink, broadcast information is mapped to a BCCH (Broadcast
Control Channel) as a logical channel and transmitted.
Part of information to be transmitted via the BCCH is mapped to a
BCH (Broadcast Channel) as a transport channel. Information mapped
to the BCH is transmitted to mobile stations UE within the
corresponding cell via a P-BCH (Physical Broadcast Channel) as a
physical channel.
Part of information to be transmitted via the BCCH is also mapped
to a DL-SCH (Downlink Shared Channel) as a transport channel.
Information mapped to the DL-SCH is transmitted to mobile stations
UE within the corresponding cell via the PDSCH as a physical
channel.
In the mobile communication system in accordance with this
embodiment, a PUSCH (Physical Uplink Shared Channel) shared by
mobile stations UE and a PUCCH (Physical Uplink Control Channel)
are used in uplink.
User data (i.e. typical data signals) are transmitted via the
PUSCH.
Downlink quality information (CQI: Channel Quality Indicator) used
for scheduling processing and for AMCS (Adaptive Modulation and
Coding Scheme) of the PDSCH, and acknowledgement information for
the PDSCH are transmitted via the PUCCH.
The downlink quality information may be also referred to as a "CSI
(Channel State Indicator)", which is an indicator collectively
representing a CQI, a PMI (Pre-coding Matrix Indicator), and a RI
(Rank Indicator).
The acknowledgement information is expressed as either ACK
(Acknowledgement) indicating that a transmission signal is
successfully received or NACK (Negative Acknowledgement) indicating
that a transmission signal is not successfully received.
When carrier aggregation as described below is applied, operations
in the communication channels used in the mobile communicate system
in accordance with this embodiment may be performed in a single
component carrier or across plural component carriers. For example,
downlink scheduling information may be transmitted by one component
carrier, and a physical downlink shared channel corresponding to
this downlink scheduling information may be transmitted by another
component carrier. Alternatively, an uplink scheduling grant may be
transmitted by one component carrier and a physical uplink shared
channel corresponding to this uplink scheduling grant may be
transmitted by another component carrier. Such a scheduling may be
referred to as cross-carrier scheduling.
In the LTE-Advanced system, carrier aggregation may be applied. In
other words, communications in uplink or downlink are performed
using plural component carriers.
A component carrier corresponds to a single system carrier in the
LTE system. In the LTE system, communications are performed on a
single component carrier. In the LTE-Advanced system, on the other
hand, communications may be performed on two or more component
carriers.
For example, as shown in FIG. 4, a cell (first communication area)
in which a first component carrier (F1 in FIG. 4) is used
geographically overlaps with a cell (second communication area) in
which a second component carrier (F2 in FIG. 4) is used in the
mobile communication system in accordance with this embodiment.
Although FIG. 4 shows that the first communication area almost
coincides with the second communication area, the first
communication area may at least partially overlap with the second
communication area.
Although not shown in FIG. 4, a third component carrier may be used
in addition to the first component carrier and the second component
carrier. Alternatively, four or more component carriers may be
used.
In the following description, it is assumed that carrier
aggregation is applied using a first component carrier (hereinafter
referred to as a "first carrier") and a second component carrier
(hereinafter referred to as a "second carrier").
Also, the first carrier is the primary component carrier, and the
second carrier is the secondary component carrier. The primary
component carrier is the most important component carrier among
plural component carriers. The primary component carrier is a
carrier in which there is not a de-activated state. That is, the
primary component carrier is a carrier that is always
activated.
The second carrier is the secondary component carrier, in which
there are a de-activated state and an activated state. That is, in
the second carrier, there are a non-activated state and an
activated state.
In general, the number of the primary component carrier is one, and
the number of the secondary component carrier(s) may be one or may
be equal to or greater than two.
When the second carrier is not activated, that is, when the second
carrier is in a de-activated state, data transmission and reception
on the second carrier is not performed basically, and cell search,
measurement or radio link monitoring is performed at a reduced
frequency. The radio link monitoring may be performed or may not be
performed. In this case, battery saving in the mobile station UE is
realized since the mobile station UE can reduce load of processing
for the second carrier, that is, load of processing of cell search,
measurement, or radio link monitoring.
On the other hand, when the second carrier is activated, that is,
when the mobile station UE is in an activated state, data
transmission and reception are performed on the second carrier, and
cell search, measurement or radio link monitoring are performed at
a proper frequency. The proper frequency may be a frequency
necessary for properly performing handover in the second carrier,
for example.
Next, operation of the mobile station and the radio base station in
accordance with the present embodiment is described. More
specifically, operation of communications in the first carrier and
the second carrier, and operation of cell search, measurement or
radio link monitoring are described in a case where there are the
first carrier that is the primary component carrier and the second
carrier that is the secondary component carrier, and a measurement
gap for measurement of the second carrier is set. As for the second
carrier, there are a case where the second carrier is in an
activated state and a case where the second carrier is in a
de-activated state. In the operation of the mobile station and the
radio base station in accordance with the present embodiment, the
measurement gap for measuring the second carrier is applied only
when the second carrier is in a de-activated state, and the
measurement gap is not applied when the second carrier is in an
activated state. Details of the measurement gap are described
below.
In FIG. 5, the second carrier is in an activated state during a
period until point C1, and the second carrier is in a de-activated
state after the point C1. A measurement gap is defined in the first
carrier for measuring the second carrier. More specifically, each
of the section B1 and the section B2 is a section defined as the
measurement gap. The section B1 is a section where the second
carrier is in an activated state and the measurement gap is
applied. The section B2 is a section where the second carrier is in
a de-activated state and the measurement gap is applied. The
section B3 is a section in which the measurement gap is not
applied.
As mentioned above, the measurement gap is a gap section for
measuring a carrier of a different frequency or a carrier of a
different mobile communication system, for example. The size may be
a value of 6 ms, for example. The size of the measurement gap may
be a value greater than 6 ms, such as 8 ms and 9 ms. Also, the
period of the measurement gap may be a value of 40 ms or 80 ms, for
example. Or, the period of the measurement gap may be a value,
other than the 40 ms and 80 ms, such as 20 ms and 1280 ms, for
example. As long as timings of gap sections agrees with each other
between the radio base station eNB and the mobile station UE, any
pattern or any form of measurement gaps may be set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the mobile
station UE and the radio base station eNB perform communication of
the first carrier without consideration of the measurement gap
(section B1). That is, when the second carrier is activated, the
mobile station UE and the radio base station eNB perform
commemoration of the first carrier even in the measurement gap that
is for measuring the second carrier.
Communication of the first carrier in the mobile station UE may
include processing for receiving a downlink signal in downlink, and
may include processing for transmitting an uplink signal in uplink,
for example. Also, communication of the first carrier in the mobile
station UE may include cell search, measurement, and radio link
monitoring for the first carrier. Communication of the first
carrier in the radio base station eNB may include processing for
transmitting a downlink signal in downlink, and may include
processing for receiving an uplink signal in uplink.
On the other hand, in a case where the second carrier is in a
de-activated state, that is, in a case where the second carrier is
not activated, the mobile station UE and the radio base station eNB
do not perform communication of the first carrier considering the
measurement gap (section B2). That is, when the second carrier is
not activated, the mobile station UE and the radio base station eNB
do not perform communication of the first carrier in the
measurement gap that is for measuring the second carrier.
Also, in a case where the second carrier is in an activated state,
that is, in a case where the second carrier is activated, the
mobile station UE may perform measurement of the second carrier,
that is, may perform cell search, measurement, or radio link
monitoring without consideration of the measurement gap (section
B1). To perform measurement of the second carrier without
consideration of the measurement gap (section B1) may mean to
perform measurement of the second carrier in an arbitrary timing in
the section B1 or the section B3.
On the other hand, in a case where the second carrier is in a
de-activated state, that is, in a case where the second carrier is
not activated, the mobile station UE may perform measurement of the
second carrier, that is, may perform cell search, measurement, or
radio link monitoring in the measurement gap (section B2).
In a section (section B3) where the measurement gap is not applied,
the mobile station UE and the radio base station eNB may perform
communication of the first carrier irrespective of whether the
second carrier is in an activated state or in a de-activated
state.
As mentioned above, although the section B1 is set as a measurement
gap in terms of signaling, the section B1 may be regarded as a
section where the measurement gap is not applied since the second
carrier is in an activated state. Or, the section B1 may be
regarded as a section that is not set as a measurement gap in terms
of signaling since the measurement gap for measuring the second
carrier is applied only when the second carrier is in a
de-activated state. In the latter case, the section B1 may be
regarded as a measurement gap that is set when the second carrier
is assumed to be in a de-activated state.
Effects of the present embodiment are described in the
following.
In a case where the second carrier is in an activated state, a
receiver of the mobile station UE is in a state shown in FIG. 2, so
that the mobile station UE can receive both of the signals of the
first carrier and the second carrier at the same time. In this
case, it becomes possible that the mobile station UE performs
measurement of the second carrier without a measurement gap for
measuring the second carrier, so that the measurement gap can be
neglected. Thus, in a case where the second carrier is in an
activated state, the mobile station UE and the radio base station
eNB perform communication of the first carrier by neglecting the
measurement gap for measuring the second carrier, so that it
becomes possible to avoid deterioration of throughput of the first
carrier due to a measurement gap.
On the other hand, in a case where the second carrier is in a
de-activated state, a receiver of the mobile station UE is
basically in a state of FIG. 3, so that the mobile station UE can
receive only a signal of the first carrier. In this case, the
mobile station UE performs measurement of the second carrier using
a measurement gap for measuring the second carrier, and, the mobile
station UE and the radio base station eNB stop communication of the
first carrier. Accordingly, a predetermined measurement gap is set
between the mobile station UE and the radio base station eNB. In
the measurement gap, the mobile station UE performs measurement of
the second carrier, and the mobile station UE and the radio base
station eNB do not perform communication of the first carrier, so
that it becomes possible to avoid an above-mentioned event that
data to be transmitted and received by the mobile station UE is
lost in the mobile station UE.
To wrap up, according to the present embodiment, in a state where a
measurement gap is set for measuring the second carrier that is the
secondary component carrier, when the secondary component carrier
is activated, deterioration of throughput due to the measurement
gap can be avoided by neglecting the measurement gap. On the other
hand, when the secondary component carrier is not activated, by
performing measurement of the second carrier while stopping
communication of the first carrier in consideration of the
measurement gap, it becomes possible to avoid an event in which
data to be transmitted and received by the mobile station UE is
lost in the mobile station UE.
Although transition between the activated state and the
de-activated state is performed in the MAC layer in order to
perform control more quickly, setting of the measurement gap is
performed in the RRC layer that is an upper layer of the MAC layer.
Thus, if the measurement gap is set or released according to the
transition between the activated state and the de-activated state,
the advantage of control in the MAC layer in which control is
performed quickly is lost. That is, it is necessary that the
setting of the measurement gap is performed irrespective of the
activated state or the de-activated state. In other words,
according to the mobile station and the radio base station
apparatus of the present embodiment, it becomes possible to control
whether to use the measurement gap without setting a measurement
gap in the RRC layer, so that it becomes possible to perform proper
measurement while maintaining the advantage of the
activation/de-activation control in which control is performed
quickly in the MAC layer.
In the example of FIG. 5, although a periodic gap of a
predetermined length is applied as the measurement gap, instead of
this, periodic gaps of two divided gap sections may be applied as
the measurement gap as shown in FIG. 6. The section between the two
gap sections is a section in which no measurement gap is applied,
that is, the section between the two gap sections is a section
similar to the section B3 shown in FIG. 5. The size of each of the
two gap sections may be 2 ms, for example. Or, the size of each of
the two gap sections may be a value other than 2 ms.
The measurement gap shown in FIG. 6 may be represented as a
measurement gap in which two sets of gap sections having the same
period are set and a time between gap sections of the two sets is
constant as shown in FIG. 7.
Or, the measurement gap shown in FIG. 6 may be represented as a
measurement gap including two gap sections separated by a
predetermined time as shown in FIG. 8. In this case, the
measurement gap including the two gap sections separated by the
constant time may be provided at a constant period like a normal
measurement gap.
As mentioned above, when the receiver of the mobile station UE
changes from the state of FIG. 2 to the state of FIG. 3, or changes
from the state of FIG. 3 to the state of FIG. 2, it is necessary to
stop communication of the first carrier and the second carrier.
That is, the mobile station UE needs to stop communication on the
first carrier and the second carrier only in a section of
transition between a state where the mobile station UE performs
communication only on the first carrier and a state where the
mobile station UE performs communication on both of the first
carrier and the second carrier. In other words, in a center section
of the section B2 shown in FIG. 5, the mobile station UE can
receive signals of both of the first carrier and the second
carrier. Thus, it is not necessary to define the center section as
a measurement gap. Therefore, as shown in FIGS. 6-8, a measurement
gap is divided into two gap sections and the section between two
gap sections is not set as a measurement gap, so that sections
where communication of the first carrier is stopped can be
decreased. As a result, it becomes possible to improve throughput
of communication of the first carrier.
In the separated two gap sections shown in FIGS. 6-8, the size of
the temporally first gap section may be greater than the size of
the temporally second gap section as shown in FIG. 9. Effects by
setting the size of the temporally first gap section to be greater
than the size of the temporally second gap section will be
described later.
More specifically, the temporally first gap section and the
temporally second gap section may be 6 ms and 1 ms, respectively,
for example. Or, the temporally first gap section and the
temporally second gap section may be 4 ms and 2 ms, respectively,
for example. Or, the sizes may be other values as long as the size
of the temporally first gap section is greater than the size of the
temporally second gap section.
In the example shown in FIG. 5, a constant length of gap is
periodically applied as a measurement gap. Instead of that, as
shown in FIG. 14, a measurement section for SCC (Secondary
Component Carrier) including four sections may be applied. The four
sections may be called a first section, a second section, a third
section and a fourth section from the top in terms of time. Similar
to the measurement gap for measuring the second carrier shown in
FIGS. 5 and 6, the measurement section for SCC is applied only when
the second carrier is in a de-activated state, and the measurement
section for SCC is not applied when the second carrier is in an
activated state. That is, in this case, the measurement section for
SCC is neglected.
For example, sizes of the first section, the second section, the
third section and the fourth section may be 2 ms, 4 ms, 5 ms and 2
ms, respectively. Or, sizes of the first section, the second
section, the third section and the fourth section may be values
other than the above-mentioned values.
The first section and the fourth section of the measurement section
for SCC are equivalent to the divided two gap sections of FIGS.
6-9. That is, the first section and the fourth section are regarded
as times when a receiver of the mobile station UE performs
switching of a center frequency and the like, so that communication
of the first carrier is not performed. That is, each of the first
section and the fourth section is regarded as a measurement gap,
and communication of the first carrier is not performed. That is,
in the first section and the fourth section, the radio base station
eNB and the mobile station UE do not perform communication of the
first carrier. In addition, for similar reasons, communication of
the second carrier is not performed in the first section and the
fourth section.
For the first carrier, the second section and the third section of
the measurement section for SCC are equivalent to the section
between the divided two gap sections of FIGS. 6-9. In this case, in
each of the second section and the third section, the receiver of
the mobile station UE is in a state of FIG. 2, so that
communication of the first carrier is performed. That is, in the
second section and the third section, the radio base station eNB
and the mobile station UE perform communication of the first
carrier. That is, each of the second section and the third section
is not a measurement gap for the first carrier, and is regarded as
a normal section, so that communication of the first carrier is
performed.
Also for the second carrier, the second section and the third
section of the measurement section for SCC are equivalent to the
section between the divided two gap sections of FIGS. 6-9. However,
in a case where the second carrier is in a de-activated state, the
mobile station UE performs measurement on the second carrier with
low frequency, that is, performs cell search, measurement, and
measurement for path loss of the serving cell, for example, with
low frequency. Thus, it is desirable that the mobile station UE
performs measurement on the second carrier again before starting
communication so as to improve accuracy of the measurement and
improve quality of communication. Therefore, in the second section
of the measurement section for SCC, operation may be adopted in
which the mobile station UE performs measurement of the second
carrier, and communication of the second carrier is not performed
between the mobile station UE and the radio base station eNB. That
is, in the second section, the radio base station eNB and the
mobile station UE do not perform communication of the second
carrier. Then, in the third section of the measurement section for
SCC, communication of the second carrier is performed. That is, in
the third section, the radio base station eNB and the mobile
station UE performs communication of the second carrier. The mobile
station UE may perform measurement of the second carrier also in
the third section of the measurement section for SCC.
That is, in the second section of the measurement section for SCC,
the mobile station UE performs cell search or measurement of the
second carrier, and measurement of path loss, and the mobile
station UE does not perform either uplink transmission or downlink
reception on the second carrier. Then, the mobile station UE
performs uplink transmission and downlink reception on the second
carrier in the third section of the measurement section for SCC.
Also, in the second section of the measurement section for SCC, the
radio base station eNB does not perform either uplink reception or
downlink transmission on the second carrier, and the radio base
station eNB performs uplink reception and downlink transmission on
the second carrier in the third section of the measurement section
for SCC.
Since measurement of path loss and the like is unnecessary for
downlink communication, the downlink communication may be performed
in both of the second section and the third section. In this case,
in the second section, only uplink communication is not performed.
That is, in the second section of the measurement section for SCC,
the mobile station UE performs cell search or measurement of the
second carrier, and measurement of path loss, and performs downlink
reception, and the mobile station UE does not perform uplink
transmission on the second carrier. Then, in the third section of
the measurement section for SCC, the mobile station UE performs
both of uplink transmission and downlink reception on the second
carrier. Also, in the second section of the measurement section for
SCC, the radio base station eNB performs downlink transmission in
the second carrier, but does not perform uplink reception. In the
third section of the measurement section for SCC, the radio base
station eNB performs both of uplink reception and downlink
transmission on the second carrier.
The operation of the mobile station UE and the radio base station
eNB related to measurement gap of the present embodiment described
with reference to FIGS. 5-9 and 14 is applied only when the first
carrier and the second carrier belong to the same frequency band,
and may not be applied when the first carrier and the second
carrier belong to different frequency bands.
In general, in a case where the first carrier and the second
carrier belong to different frequency bands, the mobile station UE
has respective receivers for the first carrier and the second
carrier. Thus, switching of the center frequency and the like shown
in FIGS. 2 and 3 does not occur, so that loss of data due to the
switching does not occur. Thus, in the case where the first carrier
and the second carrier belong to different frequency bands, the
above-mentioned operation of the mobile station UE and the radio
base station eNB related to measurement gap of the present
embodiment becomes unnecessary. In other words, only when the first
carrier and the second carrier belong to the same frequency band,
the mobile station UE and the radio base station eNB set a
measurement gap, and only when the second carrier is in a
de-activated state, the mobile station UE and the radio base
station eNB regard that the measurement gap exists, and when the
second carrier is in an activated state, the mobile station UE and
the radio base station eNB regard that the measurement gap does not
exist. In a case where the first carrier and the second carrier
belong to different frequency bands, the mobile station UE and the
radio base station eNB do not set the measurement gap. In this
case, when the first carrier and the second carrier belong to
different frequency bands, it becomes possible that the mobile
station UE performs measurement of the second carrier at an
arbitrary timing. As a result, it becomes possible to perform
measurement processing more flexibly.
In addition, in a case where there are plural secondary carriers,
the section B1 and the section B2 shown in FIGS. 5 and 6 or the
measurement section for SCC may be set in the same time among the
plural secondary carriers (second carriers in the example shown in
the above-mentioned figures).
As shown in FIG. 10, the mobile station UE includes a first
communicating unit 102, a second communicating unit 104, an
activation/de-activation control unit 106, and a gap control unit
108. The first communicating unit 102 includes a first downlink
receiving unit 102A, a first uplink transmitting unit 102B, and a
first measuring unit 102C. The second communicating unit 104
includes a second downlink receiving unit 104A, a second uplink
transmitting unit 104B, and a second measuring unit 104C.
It should be noted that FIG. 10 shows functional units associated
with baseband processing in the mobile station UE, but does not
show functional units associated with RF (radio frequency)
processing in the mobile station UE. Since the receiver shown in
FIG. 2 or 3 is included in functional units associated with RF
processing, these units are not shown in FIG. 10. The configuration
of the mobile station UE in accordance with this embodiment can be
used regardless of the functional units associated with RF
processing.
The first communicating unit 102, the first downlink receiving unit
102A, the first uplink transmitting unit 102B, the first measuring
unit 102C, the second communicating unit 104, the second downlink
receiving unit 104A, the second uplink transmitting unit 104B, the
second measuring unit 104C, the activation/de-activation control
unit 106, and the gap control unit 108 are connected with each
other.
The first communicating unit 102 performs communications related to
the first carrier. For example, the first communicating unit 102
performs downlink reception and uplink transmission on the first
carrier, and cell search, measurement, radio link monitoring, or
the like on the first carrier.
In the following, operation of the first communicating unit 102 is
described in a case where the measurement gap shown in FIGS. 5 and
6 is set.
When the second carrier is in an activated state, that is, when the
second carrier is activated, the first communicating unit 102
performs communication of the first carrier without consideration
of the measurement gap (section B1). That is, when the second
carrier is activated, the first communicating unit 102 performs
communication of the first carrier even in the measurement gap for
measuring the second carrier.
Also, in a case where the second carrier is in a de-activated
state, that is, in a case where the second carrier is not
activated, the first communicating unit 102 does not perform
communication of the first carrier in consideration of the
measurement gap (section B2). That is, when the second carrier is
not activated, the first communicating unit 102 does not perform
communication of the first carrier in the measurement gap for
measuring the second carrier.
In the following, operation of the first communicating unit 102 is
described in a case where the measurement gap for SCC shown in FIG.
14 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
communicating unit 102 performs communication of the first carrier
without consideration of the measurement section for SCC. That is,
in the case where the second carrier is activated, the first
communicating unit 102 performs communication of the first carrier
even in the first section, the second section, the third section
and the fourth section in the measurement section for SCC.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
communicating unit 102 does not perform communication of the first
carrier in the first section and the fourth section of the
measurement section for SCC in consideration of the measurement
section for SCC. That is, when the second carrier is not activated,
the first communicating unit 102 does not perform communication of
the first carrier in the first section and the fourth section in
the measurement section for SCC. In a case where the second carrier
is not activated, the first communicating unit 102 may perform
communication of the first carrier in the second section and the
third section in the measurement section for SCC.
The first downlink receiving unit 102A receives downlink signals on
the first carrier. For example, the downlink signals may be the
PDSCH or the PDCCH. Alternatively, the downlink signals may be a
P-BCH as broadcast information, a PSS (Primary Synchronization
Signal) or an SSS (Secondary Synchronization Signal) as
synchronization signals, or downlink reference signals.
In the following, operation of the first downlink receiving unit
102A is described in a case where the measurement gap shown in
FIGS. 5 and 6 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
downlink receiving unit 102A performs downlink signal reception on
the first carrier without consideration of the measurement gap
(section B1). That is, when the second carrier is activated, the
first downlink receiving unit 102A performs downlink signal
reception on the first carrier even in the measurement gap for
measuring the second carrier.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
downlink receiving unit 102A does not perform downlink signal
reception on the first carrier in consideration of the measurement
gap (section B2). That is, when the second carrier is not
activated, the first downlink receiving unit 102A does not perform
downlink signal reception on the first carrier in the measurement
gap for measuring the second carrier.
In the following, operation of the first downlink receiving unit
102A is described in a case where the measurement gap for SCC shown
in FIG. 14 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
downlink receiving unit 102A performs downlink signal reception on
the first carrier without consideration of the measurement section
for SCC. That is, in the case where the second carrier is
activated, the first downlink receiving unit 102A performs downlink
signal reception on the first carrier even in the first section,
the second section, the third section and the fourth section in the
measurement section for SCC.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
downlink receiving unit 102A does not perform downlink signal
reception on the first carrier in the first section and the fourth
section of the measurement section for SCC in consideration of the
measurement section for SCC. That is, when the second carrier is
not activated, the first downlink receiving unit 102A does not
perform downlink signal reception on the first carrier in the first
section and the fourth section in the measurement section for SCC.
In a case where the second carrier is not activated, the first
downlink receiving unit 102A may perform downlink signal reception
on the first carrier in the second section and the third section in
the measurement section for SCC.
The first uplink transmitting unit 102B transmits uplink signals on
the first carrier. For example, the uplink signals may be the PUSCH
or the PUCCH. Alternatively, the uplink signals may be sounding
reference signals, demodulation reference signals, or signals on a
random access channel.
In the following, operation of the first uplink transmitting unit
102B is described in a case where the measurement gap shown in
FIGS. 5 and 6 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
uplink transmitting unit 102B performs uplink signal reception
without consideration of the measurement gap (section B1). That is,
when the second carrier is activated, the first uplink transmitting
unit 102B performs uplink signal transmission on the first carrier
even in the measurement gap for measuring the second carrier.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
uplink transmitting unit 102B does not perform uplink signal
transmission on the first carrier in consideration of the
measurement gap (section B2). That is, when the second carrier is
not activated, the first uplink transmitting unit 102B does not
perform uplink signal transmission on the first carrier in the
measurement gap for measuring the second carrier.
In the following, operation of the first uplink transmitting unit
102B is described in a case where the measurement gap for SCC shown
in FIG. 14 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
uplink transmitting unit 102B performs uplink signal transmission
on the first carrier without consideration of the measurement
section for SCC. That is, in the case where the second carrier is
activated, the first uplink transmitting unit 102B performs uplink
signal transmission on the first carrier even in the first section,
the second section, the third section and the fourth section in the
measurement section for SCC.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
uplink transmitting unit 102B does not perform uplink signal
transmission in consideration of the measurement section for SCC.
That is, when the second carrier is not activated, the first uplink
transmitting unit 102B does not perform uplink signal transmission
on the first carrier in the first section and the fourth section in
the measurement section for SCC. In a case where the second carrier
is not activated, the first uplink transmitting unit 102B may
perform uplink signal transmission on the first carrier in the
second section and the third section in the measurement section for
SCC.
The first measuring unit 102C performs measurement processing such
as cell search, measurement, radio link monitoring or the like on
the first carrier.
In the following, operation of the first measuring unit 102C is
described in a case where the measurement gap shown in FIGS. 5 and
6 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
measuring unit 102C performs measurement processing such as cell
search, measurement, or radio link monitoring on the first carrier
without consideration of the measurement gap (section B1). That is,
when the second carrier is activated, the first measuring unit 102C
performs measurement processing such as cell search, measurement,
or radio link monitoring on the first carrier even in the
measurement gap for measuring the second carrier.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
measuring unit 102C does not perform measurement processing such as
cell search, measurement, or radio link monitoring on the first
carrier in consideration of the measurement gap (section B2). That
is, when the second carrier is not activated, the first measuring
unit 102C does not perform measurement processing such as cell
search, measurement, or radio link monitoring on the first carrier
in the measurement gap for measuring the second carrier.
In the following, operation of the first measuring unit 102C is
described in a case where the measurement gap for SCC shown in FIG.
14 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
measuring unit 102C performs measurement processing such as cell
search, measurement, or radio link monitoring on the first carrier
without consideration of the measurement section for SCC. That is,
in the case where the second carrier is activated, the first
measuring unit 102C performs measurement processing such as cell
search, measurement, or radio link monitoring on the first carrier
even in the first section, the second section, the third section
and the fourth section in the measurement section for SCC.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
measuring unit 102C does not perform measurement processing such as
cell search, measurement, or radio link monitoring on the first
carrier in consideration of the measurement section for SCC. That
is, when the second carrier is not activated, the first measuring
unit 102C does not perform measurement processing such as cell
search, measurement, or radio link monitoring on the first carrier
in the first section and the fourth section in the measurement
section for SCC. In a case where the second carrier is not
activated, the first measuring unit 102C may perform measurement
processing such as cell search, measurement, or radio link
monitoring on the first carrier in the second section and the third
section in the measurement section for SCC.
The second communicating unit 104 performs communications related
to the second carrier. For example, the second communicating unit
104 performs downlink reception and uplink transmission on the
second carrier, and cell search, measurement, radio link
monitoring, or the like on the second carrier.
As mentioned above, in a case where the second carrier is in an
activated state, the second communicating unit 104 performs normal
data transmission and reception, and performs measurement of the
second carrier at a proper frequency. On the other hand, in a case
where the second carrier is in a de-activated state, the second
communicating unit 104 does not perform normal data transmission
and reception, and performs measurement of the second carrier by
reducing the frequency of measurement.
Operation of the second communicating unit 104 is described below
in a case where the measurement section for SCC shown in FIG. 14 is
set. In a case where the second carrier is in an activated state,
the second communicating unit 104 performs normal data transmission
and reception on the second carrier by neglecting the measurement
section for SCC, and performs measurement of the second carrier at
a proper frequency. On the other hand, in a case where the second
carrier is in a de-activated state, as mentioned above, the second
communicating unit 104 may perform uplink transmission and downlink
transmission on the second carrier, and measurement of the second
carrier only in a part of the measurement section for SCC. That is,
in the case where the second carrier is in a de-activated state,
the second communicating unit 104 may perform uplink transmission
and downlink reception only in the third section of the measurement
section for SCC, and does not perform uplink transmission and
downlink reception in the first section, the second section and the
fourth section of the measurement section for SCC.
The second downlink receiving unit 104A receives downlink signals
on the second carrier. For example, the downlink signals may be the
PDSCH or the PDCCH. Alternatively, the downlink signals may be the
P-BCH as broadcast information, the PSS (Primary Synchronization
Signal) or the SSS (Secondary Synchronization Signal) as
synchronization signals, or downlink reference signals.
In a case where the second carrier is in a de-activated state, the
second downlink receiving unit 104A does not perform downlink
signal reception on the second carrier.
Operation of the second downlink receiving unit 104A is described
below in a case where the measurement section for SCC shown in FIG.
14 is set. In a case where the second carrier is in an activated
state, the second downlink receiving unit 104A receives a downlink
signal on the second carrier by neglecting the measurement section
for SCC. In a case where the second carrier is in a de-activated
state, the second downlink receiving unit 104A may receive a
downlink signal on the second carrier only in the third section of
the measurement section for SCC. That is, in the case where the
second carrier is in a de-activated state, the second downlink
receiving unit 104A does not receive the downlink signal in the
first section, the second section and the fourth section of the
measurement section for SCC. As mentioned above, in a case where
the second carrier is in a de-activated state, the second downlink
receiving unit 104A may receive a downlink signal only in the
second section and the third section in the measurement section for
SCC instead of receiving the downlink signal only in the third
section in the measurement section for SCC.
The second uplink transmitting unit 104B transmits uplink signals
on the second carrier. For example, the uplink signals may be the
PUSCH or the PUSCH. Alternatively, the uplink signals may be
sounding reference signals, demodulation reference signals, or
signals on the random access channel.
In a case where the second carrier is in a de-activated state, the
second uplink transmitting unit 104B does not perform uplink signal
reception on the second carrier.
Operation of the second uplink transmitting unit 104B is described
below in a case where the measurement section for SCC shown in FIG.
14 is set. In a case where the second carrier is in an activated
state, the second uplink transmitting unit 104B transmits an uplink
signal on the second carrier by neglecting the measurement section
for SCC. In a case where the second carrier is in a de-activated
state, the second uplink transmitting unit 104B may transmit an
uplink signal only in the third section of the measurement section
for SCC. That is, in the case where the second carrier is in a
de-activated state, the second uplink transmitting unit 104B does
not transmit the uplink signal in the first section, the second
section and the fourth section of the measurement section for
SCC.
The second measuring unit 104C performs measurement processing such
as cell search, measurement, or radio link monitoring on the second
carrier.
In the following, operation of the second measuring unit 104C is
described in a case where the measurement gap shown in FIGS. 5 and
6 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the second
measuring unit 104C may perform measurement of the second carrier,
that is, may perform cell search, measurement, or radio link
monitoring without consideration of the measurement gap (section
B1). To perform measurement of the second carrier without
consideration of the measurement gap (section B1) may mean to
perform measurement of the second carrier at an arbitrary timing in
the section B1 or the section B3, for example.
On the other hand, in a case where the second carrier is in a
de-activated state, that is, in a case where the second carrier is
not activated, the second measuring unit 104C may perform
measurement of the second carrier, that is, may perform cell
search, measurement, or radio link monitoring in the measurement
gap (section B2).
Also, in a case where a measurement gap including two gap sections
separated by a constant time is set as a measurement gap for
measuring the second carrier as shown in FIGS. 6-8, the second
measuring unit 104C may perform measurement processing such as cell
search, measurement, or radio link monitoring or the like on the
second carrier in a temporally first gap section in the two gap
sections. The measurement may include after-mentioned measurement
of path loss.
In the following, the meaning is described that the second
measuring unit 104C performs measurement processing such as cell
search, measurement, radio link monitoring or the like on the
second carrier in the temporally first gap section in the two gap
sections.
For example, it is assumed that, in a case where the second carrier
is in a de-activated state, data to transmit occurs, and uplink
transmission occurs in the section between the two gap sections. In
this case, it is desirable that transmission power for the uplink
transmission is determined based on the newest path loss as much as
possible. In this case, if path loss is measured in the section
between the two gap sections, it is difficult to reflect the result
of the measured path loss in determination of transmission power
for the uplink transmission, in consideration of process delay and
the like. In other words, by measuring path loss in the section
before the section between the two gap sections, the transmission
power for the uplink transmission is determined based on the newest
path loss. As a result, quality of communication can be
improved.
In the above-mentioned example, the path loss is estimated from
received power RSRP of the downlink reference signal. Thus, to
measure the path loss in the temporally first gap section in the
two gap sections means to perform measurement of RSRP (so called
measurement) in the temporally first gap section in the two gap
sections.
Not only for the measurement of RSRP (so called measurement), but
also for cell search or radio link monitoring, it is desirable to
perform cell search or radio link monitoring in the temporally
first gap section of the two gap sections since processing based on
the measurement result becomes possible in the section between the
two gap sections.
In the temporally second gap section in the two gap sections, only
processing such as switching of the center frequency of the
receiver occurs as mentioned above. On the other hand, in the
temporally first gap section in the two gap sections, processing of
the above-mentioned cell search, measurement, or radio link
monitoring is performed in addition to the processing such as the
switching of the center frequency of the receiver. Thus, the size
of the temporally first gap section in the two gap sections may be
set to be greater than the temporally second gap section in the two
gap sections.
That is, the mobile station UE and the radio base station eNB may
perform processing, in which the mobile station UE and the radio
base station eNB do not perform communication processing on the
first carrier in the temporally first gap section of the two gap
sections and in the temporally second gap section of the two gap
sections by regarding that data transmission and reception on the
first carrier cannot be performed in the sections. Also, the size
of the temporally first gap section in the two gap sections may be
set to be greater than the size of the temporally second gap
section in the two gap sections.
Operation of the second measuring unit 104C is described below in a
case where the measurement section for SCC shown in FIG. 14 is set.
In a case where the second carrier is in an activated state, the
second measuring unit 104C performs measurement of the second
carrier by neglecting the measurement section for SCC. In a case
where the second carrier is in a de-activated state, the second
measurement unit 104C may perform measurement of the second carrier
in the second section in the measurement section for SCC. For
example, the measurement may be cell search or measurement of a
serving cell or an adjacent cell, measurement of path loss of the
serving cell, or radio link monitoring. The effect in which the
second measuring unit 104C performs measurement of the second
carrier in the second section is the same as the effect of
performing measurement in the temporally first gap section in the
two gap sections. Thus, the description is not given.
The activation/de-activation control unit 106 is configured to
perform management on whether the second component carrier of the
mobile station UE is in a de-activated state or in an activated
state. More specifically, the activation/de-activation control unit
106 is configured to perform management on whether the second
carrier that is the secondary component carrier is in an activated
state or in a de-activated state. The activation/de-activation
control unit 106 reports information indicating whether the second
carrier is in an activated state or in a de-activated state, that
is, whether the second carrier is activated or not activated, to
the first communicating unit 102 (the first downlink receiving unit
102A, the first uplink transmitting unit 102B, the first measuring
unit 102C), the second communicating unit 104 (the second downlink
receiving unit 104A, the second uplink transmitting unit 104B, the
second measuring unit 104C) and the gap control unit 108.
The gap control unit 108 controls a measurement gap. More
specifically, the gap control unit 108 manages a measurement gap
for measuring a carrier with a different frequency or a carrier for
a different radio communication system. The gap control unit 108
provides information about a subcarrier in which the measurement
gap is provided to the activation/de-activation control unit 106,
the first communicating unit 102 (the first downlink receiving unit
102A, the first uplink transmitting unit 102B, and the first
measuring unit 102C), and the second communicating unit 104 (the
second downlink receiving unit 104A, the second uplink transmitting
unit 104B, and the second measuring unit 104C).
The measurement gap includes the measurement gap for measuring the
second carrier described with reference to FIGS. 5-9 or the
measurement section for SCC described with reference to FIG. 14 in
addition to the measurement gap for measurement on different
frequency carriers or measurement on carriers of different mobile
communication systems. That is, the gap control unit 108 manages
the measurement gap for measuring the second carrier or the
measurement section for SCC, and reports information on the
measurement gap or the measurement section for SCC, that is,
information on a subframe in which the measurement gap or the
measurement section for SCC is set, for example, to the
activation/de-activation control unit 106, the first communicating
unit 102 (the first downlink receiving unit 102A, the first uplink
transmitting unit 102B, the first measuring unit 102C), and the
second communicating unit 104 (the second downlink receiving unit
104A, the second uplink transmitting unit 104B, the second
measuring unit 104C). The measurement gap for measuring the second
carrier or the measurement section for SCC may be different from or
may be the same as the measurement gap for measurement of the
different frequency carriers or for measurement of carriers of
different mobile communication systems in terms of the period,
configuration of gap sections, and the length of the gap
sections.
As shown in FIG. 11, the radio base station eNB includes a first
communicating unit 202, a second communicating unit 204, an
activation/de-activation control unit 206, and a gap unit 208. The
first communicating unit 202 includes a first downlink transmitting
unit 202A and a first uplink receiving unit 202B. The second
communicating unit 204 includes a second downlink transmitting unit
204A and a second uplink receiving unit 204B. The first
communicating unit 202, the first downlink transmitting unit 202A,
the first uplink receiving unit 202B, the second communicating unit
204, the second downlink transmitting unit 204A, the second uplink
receiving unit 204B, the activation/de-activation control unit 206,
and the gap control unit 208 are connected with each other.
The first communicating unit 202 performs communications related to
the first carrier. For example, the first communicating unit 202
performs downlink transmission and uplink reception on the first
carrier.
In the following, operation of the first communicating unit 202 is
described in a case where the measurement gap shown in FIGS. 5 and
6 is set.
When the second carrier is in an activated state, that is, when the
second carrier is activated, the first communicating unit 202
performs communication of the first carrier without consideration
of the measurement gap (section B1). That is, when the second
carrier is activated, the first communicating unit 202 performs
communication of the first carrier even in the measurement gap for
measuring the second carrier.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
communicating unit 202 does not perform communication of the first
carrier in consideration of the measurement gap (section B2). That
is, when the second carrier is not activated, the first
communicating unit 202 does not perform communication of the first
carrier in the measurement gap for measuring the second
carrier.
In the following, operation of the first communicating unit 202 is
described in a case where the measurement gap for SCC shown in FIG.
14 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
communicating unit 202 performs communication of the first carrier
without consideration of the measurement section for SCC. That is,
in the case where the second carrier is activated, the first
communication unit 202 performs communication of the first carrier
even in the first section, the second section, the third section
and the fourth section in the measurement section for SCC.
Also, in a case where the second carrier is in a de-activated
state, that is, in a case where the second carrier is not
activated, the first communicating unit 202 does not perform
communication of the first carrier in the first section and the
fourth section of the measurement section for SCC in consideration
of the measurement section for SCC. That is, when the second
carrier is not activated, the first communicating unit 202 does not
perform communication of the first carrier in the first section and
the fourth section in the measurement section for SCC. In a case
where the second carrier is not activated, the first communicating
unit 202 may perform communication of the first carrier in the
second section and the third section in the measurement section for
SCC.
The first downlink transmitting unit 202A transmits downlink
signals on the first carrier. For example, the downlink signals may
be the PDSCH or the PDCCH. Alternatively, the downlink signals may
be the P-BCH as broadcast information, the PSS (Primary
Synchronization Signal) or the SSS (Secondary Synchronization
Signal) as synchronization signals, or downlink reference
signals.
In the following, operation of the first downlink transmitting unit
202A is described in a case where the measurement gap shown in
FIGS. 5 and 6 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
downlink transmitting unit 202A performs downlink signal
transmission of the first carrier without consideration of the
measurement gap (section B1). That is, when the second carrier is
activated, the first downlink transmitting unit 202A performs
downlink signal transmission on the first carrier even in the
measurement gap for measuring the second carrier.
Alternatively, in a case where the second carrier is in an
activated state, the first downlink transmitting unit 202A may
perform downlink scheduling by neglecting the measurement gap for
measuring the second carrier. That is, in a case where the second
carrier is in an activated state, the first downlink transmitting
unit 202A may perform downlink scheduling for the mobile station UE
even in the measurement gap for measuring the second carrier. The
"scheduling" indicates processing for selecting a mobile station UE
that performs communication using a shared channel in a
subframe.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
downlink transmitting unit 202A does not perform downlink signal
transmission on the first carrier in consideration of the
measurement gap (section B2). That is, when the second carrier is
not activated, the first downlink transmitting unit 202A does not
perform downlink signal transmission on the first carrier in the
measurement gap for measuring the second carrier.
Alternatively, in a case where the second carrier is in a
de-activated state, the first downlink transmitting unit 202A may
perform scheduling such that the mobile station UE does not receive
a downlink signal in the measurement gap for measuring the second
carrier. The "scheduling" indicates processing for selecting a
mobile station UE that performs communication using a shared
channel in a subframe.
In the following, operation of the first downlink transmitting unit
202A is described in a case where the measurement gap for SCC shown
in FIG. 14 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
downlink transmitting unit 202A performs downlink signal
transmission on the first carrier without consideration of the
measurement section for SCC. That is, in the case where the second
carrier is activated, the first downlink transmitting unit 202A
performs downlink signal transmission on the first carrier even in
the first section, the second section, the third section and the
fourth section in the measurement section for SCC for measuring the
second carrier.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
downlink transmitting unit 202A does not perform downlink signal
transmission in consideration of the measurement section for SCC.
That is, when the second carrier is not activated, the first
downlink transmitting unit 202A does not perform downlink signal
transmission on the first carrier in the first section and the
fourth section in the measurement section for SCC. In a case where
the second carrier is not activated, the first downlink
transmitting unit 202A may perform downlink signal transmission on
the first carrier in the second section and the third section in
the measurement section for SCC.
The first uplink receiving unit 202B receives uplink signals on the
first carrier. For example, the uplink signals may be the PUSCH or
the PUCCH. Alternatively, the uplink signals may be sounding
reference signals, demodulation reference signals, or a random
access channel.
In the following, operation of the first uplink receiving unit 202B
is described in a case where the measurement gap shown in FIGS. 5
and 6 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
uplink receiving unit 202B performs uplink signal reception on the
first carrier without consideration of the measurement gap (section
B1). That is, when the second carrier is activated, the first
uplink receiving unit 202B performs uplink signal reception on the
first carrier even in the measurement gap for measuring the second
carrier.
Alternatively, in a case where the second carrier is activated, the
first uplink receiving unit 202B may perform uplink scheduling by
neglecting the measurement gap for measuring the second carrier.
That is, in a case where the second carrier is activated, the first
uplink receiving unit 202B may perform uplink scheduling for the
mobile station UE even in the measurement gap for measuring the
second carrier. The "scheduling" indicates processing for selecting
a mobile station UE that performs communication using a shared
channel in a subframe. More specifically, the first uplink
receiving unit 202B may be configured not to transmit an uplink
scheduling grant to the mobile station UE in a corresponding
subframe of downlink such that the mobile station does not transmit
an uplink signal in the measurement gap for measuring the second
carrier. The uplink scheduling grant may be transmitted via the
first downlink transmission unit 202A.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
uplink receiving unit 202B does not perform uplink signal reception
on the first carrier in consideration of the measurement gap
(section B2). That is, when the second carrier is not activated,
the first uplink receiving unit 202B does not perform uplink signal
reception on the first carrier in the measurement gap for measuring
the second carrier.
Alternatively, in a case where the second carrier is not activated,
the first uplink receiving unit 202B may perform scheduling such
that the mobile station UE does not transmit an uplink signal in
the measurement gap for measuring the second carrier. The
"scheduling" indicates processing for selecting a mobile station UE
that, performs communication using a shared channel in a subframe.
More specifically, the first uplink receiving unit 202B may be
configured not to transmit an uplink scheduling grant to the mobile
station UE in a corresponding subframe of downlink such that the
mobile station UE does not transmit an uplink signal in the
measurement gap for measuring the second carrier. The uplink
scheduling grant may be transmitted via the first downlink
transmitting unit 202A.
In the following, operation of the first uplink receiving unit 202B
is described in a case where the measurement gap for SCC shown in
FIG. 14 is set.
In a case where the second carrier is in an activated state, that
is, in a case where the second carrier is activated, the first
uplink receiving unit 202B performs uplink signal reception on the
first carrier without consideration of the measurement section for
SCC. That is, it the case where the second carrier is activated,
the first uplink receiving unit 202B performs uplink signal
reception on the first carrier even in the first section, the
second section, the third section and the fourth section in the
measurement section for SCC for measuring the second carrier.
In a case where the second carrier is in a de-activated state, that
is, in a case where the second carrier is not activated, the first
uplink receiving unit 202B does not perform downlink signal
reception on the first carrier in consideration of the measurement
section for SCC. That is, when the second carrier is not activated,
the first uplink receiving unit 202B does not perform uplink signal
reception on the first carrier in the first section and the fourth
section in the measurement section for SCC. In a case where the
second carrier is not activated, the first uplink receiving unit
202B may perform uplink signal reception on the first carrier in
the second section and the third section in the measurement section
for SCC.
Also in the case of the measurement section for SCC shown in FIG.
14, like the gap section for measuring the second carrier shown in
FIGS. 5-9, scheduling may be performed such that uplink
communication or downlink communication does not occur in the first
section and the fourth section. That is, in the first section and
the fourth section, transmission of uplink scheduling grant or
downlink scheduling information which causes uplink or downlink
communication may be restricted.
The second communicating unit 204 performs communications related
to the second carrier. For example, the second communicating unit
204 performs downlink transmission and uplink reception and the
like on the second carrier.
As mentioned above, in a case where the second carrier is in an
activated state, the second communicating unit 204 performs normal
data transmission and reception. On the other hand, in a case where
the second carrier is in a de-activated state, the second
communicating unit 204 does not perform normal data transmission
and reception.
Operation of the second communicating unit 204 is described below
in a case where the measurement section for SCC shown in FIG. 14 is
set. In a case where the second carrier is in an activated state,
the second communicating unit 204 performs normal data transmission
and reception on the second carrier by neglecting the measurement
section for SCC. On the other hand, in a case where the second
carrier is in a de-activated state, as mentioned above, the second
communicating unit 204 may perform uplink reception or downlink
transmission on the second carrier only in a part of the
measurement section for SCC. That is, in the case where the second
carrier is in a de-activated state, the second communicating unit
204 performs uplink reception and downlink transmission only in the
third section of the measurement section for SCC, and does not
perform uplink reception and downlink transmission in the first
section, the second section and the fourth section of the
measurement section for SCC.
The second downlink transmitting unit 204A transmits downlink
signals on the second carrier. For example, the downlink signals
may be the PDSCH or the PDCCH. Alternatively, the downlink signals
may be the P-BCH as broadcast information, the PSS (Primary
Synchronization Signal) or the SSS (Secondary Synchronization
Signal) as synchronization signals, or downlink reference
signals.
In a case where the second carrier is in a de-activated state, the
second downlink transmitting unit 204A does not perform downlink
signal transmission on the second carrier.
Operation of the second downlink transmitting unit 204A is
described below in a case where the measurement section for SCC
shown in FIG. 14 is set. In a case where the second carrier is in
an activated state, the second downlink transmitting unit 204A
transmits a downlink signal on the second carrier by neglecting the
measurement section for SCC. In a case where the second carrier is
in a de-activated state, the second downlink transmitting unit 204A
may transmit a downlink signal only in the third section of the
measurement section for SCC. That is, in the case where the second
carrier is in a de-activated state, the second downlink
transmitting unit 204A does not transmit the downlink signal in the
first section, the second section and the fourth section of the
measurement section for SCC. As mentioned above, in a case where
the second carrier is in a de-activated state, the second downlink
transmitting unit 204A may transmit a downlink signal only in the
second section and the third section in the measurement section for
SCC instead of transmitting the downlink signal only in the third
section in the measurement section for SCC.
The second uplink receiving unit 204B receives uplink signals on
the second carrier. For example, the uplink signals may be the
PUSCH or the PUCCH. Alternatively, the uplink signals may be
sounding reference signals, demodulation reference signals, or the
random access channel.
In a case where the second carrier is in a de-activated state, the
second uplink receiving unit 204B does not perform uplink signal
reception on the second carrier.
In a case where the second carrier is in a de-activated state and
there is an uplink signal to be transmitted, the second uplink
receiving unit 204B may perform scheduling of uplink in the second
carrier, that is, may perform assignment of a shared channel of the
second carrier such that the uplink signal is transmitted right
after the section B2. More specifically, in a case where the second
carrier is in a de-activated state and there is an uplink signal to
be transmitted, the second uplink receiving unit 204B may transmit
an uplink scheduling grant, in downlink, that is a control signal
for instructing uplink signal transmission such that the uplink
signal is transmitted right after the section B2.
Operation of the second uplink receiving unit 204B is described
below in a case where the measurement section for SCC shown in FIG.
14 is set. In a case where the second carrier is in an activated
state, the second uplink receiving unit 204B receives an uplink
signal on the second carrier by neglecting the measurement section
for SCC. In a case where the second carrier is in a de-activated
state, the second uplink receiving unit 204B may receive an uplink
signal only in the third section of the measurement section for
SCC. That is, in the case where the second carrier is in a
de-activated state, the second uplink receiving unit 204B does not
receive the uplink signal in the first section, the second section
and the fourth section of the measurement section for SCC.
As mentioned above, in the section B2 or the measurement section
for SCC, since cell search or measurement on the second carrier is
performed, accuracy of path loss used for uplink transmission is
considered to be high. Thus, in a case where uplink transmission is
performed in a de-activated state, uplink transmission power
control is performed more properly and communication quality is
improved by instructing the mobile station UE to transmit an uplink
signal right after the section B2 or the measurement section for
SCC. Alternatively, in the same reason, in a case where the second
carrier is in a de-activated state, the radio base station eNB may
activate the second carrier right after the section B2 or the
measurement section for SCC.
In a case where a measurement gap that includes two gap sections is
set as shown in FIG. 6, uplink transmission may be instructed such
that uplink transmission is performed in a section between the two
gap sections. In this case, as shown in FIG. 14, the uplink
transmission may be performed in the second half section (third
section in FIG. 14) in sections between the two gap sections.
The activation/de-activation control unit 206 is configured to
perform management and control on whether the secondary component
carrier of each mobile station UE in a cell is in an activated
state or in a de-activated state. More specifically, the
activation/de-activation control unit 206 is configured to perform
management and control on whether the second carrier that is the
secondary component carrier is in an activated state or in a
de-activated state for each mobile station UE in the cell. The
activation/de-activation control unit 206 reports information
indicating whether the second carrier of each mobile station UE in
the cell is in an activated state or in a de-activated state, that
is, whether the second carrier is activated or not activated, to
the first communicating unit 202 (the first downlink transmitting
unit 202A, the first uplink receiving unit 202B), the second
communicating unit 204 (the second downlink transmitting unit 204A,
the second uplink receiving unit 204B) and the gap control unit
208.
The gap control unit 208 controls a measurement gap. More
specifically, the gap control unit 208 manages a measurement gap
for measuring a carrier with a different frequency or a carrier for
a different radio communication system. The gap control unit 208
provides information about a subcarrier in which the measurement
gap is provided for each mobile station in the cell to the
activation/de-activation control unit 206, the first communicating
unit 202 (the first downlink transmitting unit 202A, the first
uplink receiving unit 202B), and the second communicating unit 204
(the second downlink transmitting unit 204A, the second uplink
receiving unit 204B).
In a case where a measurement gap is set for each mobile station in
the cell, the gap control unit 208 may transmit the setting
information to each mobile station in the cell using an RRC
message. The RRC message may be reported to the mobile station UE
via the first downlink transmitting unit 202A or the second
downlink transmitting unit 202A.
The measurement gap includes the measurement gap for measuring the
second carrier described with reference to FIGS. 5-9 or the
measurement section for SCC described with reference to FIG. 14 in
addition to the measurement gap for measurement on different
frequency carriers or measurement on carriers of different mobile
communication systems. That is, the gap control unit 208 manages
the measurement gap for measuring the second carrier or the
measurement section for SCC, and the gap control unit 208 reports
information on the measurement gap or the measurement section for
SCC, that is, information on a subframe in which the measurement
gap or the measurement section for SCC is set, for example, to the
activation/de-activation control unit 206, the first communicating
unit 202 (the first downlink transmitting unit 202A, the first
uplink receiving unit 202B), and the second communicating unit 204
(the second downlink transmitting unit 204A, the second uplink
receiving unit 204B).
The measurement gap for measuring the second carrier or the
measurement section for SCC may be different from or may be the
same as the measurement gap for measurement on the different
frequency carriers or for measurement on carriers of different
mobile communication systems in terms of the period, configuration
of gap sections, and the length of the gap sections.
The measurement gap for measuring the second carrier or the
measurement section for SCC may be set as a measurement gap that is
the same as or different from the measurement gap for measurement
on the different frequency carriers or for measurement on carriers
of different mobile communication systems. When the measurement gap
for measuring the second carrier or the measurement section for SCC
is set as a measurement gap different from the measurement gap for
measurement on the different frequency carriers or for measurement
on carriers of different mobile communication systems, the
measurement gap for measuring the second carrier or the measurement
section for SCC may be set at the same time when the measurement
gap for measurement on the different frequency carriers or for
measurement on carriers of different mobile communication systems
is set.
Also, the measurement gap for measuring the second carrier or the
measurement section for SCC may be a measurement gap that is
applied only when a carrier of measurement target is in a
de-activated state.
A communication control method in the mobile station UE according
to the present embodiment is described with reference to FIG.
12.
In step S302, the mobile station UE determines whether the
secondary component carrier (secondary CC) is in a de-activated
state in a corresponding subframe. The secondary CC corresponds to
the second carrier in the above description.
When the secondary CC is in a de-activated state in the subframe
(step S302:Yes), the mobile station UE determines whether the
subframe is a gap section for measuring the secondary CC. Instead
of determining whether the subframe is a gap section for measuring
the secondary CC, the mobile station UE may determine whether the
subframe is the first section or the fourth section shown in FIG.
14.
If the subframe is a gap section for measuring the secondary CC
(step S304:YES), the mobile station UE does not perform
communication on the primary component carrier (primary CC) in the
subframe (step S306). That is, the mobile station UE does not
perform uplink transmission and downlink reception on the primary
component carrier (primary CC) in the subframe. The primary CC
corresponds to the first carrier in the above-mentioned
description.
When the secondary CC is not in the de-activated state in the
subframe (step S302:NO), or when the secondary CC is in a
de-activated state in the subframe and the subframe is not a gap
section for the secondary CC (step S304:NO), the mobile station UE
performs communication on the primary CC in the subframe (step
S308).
A communication control method in the radio base station eNB
according to the present embodiment is described with reference to
FIG. 13.
In step S402, the radio base station eNB determines whether the
secondary component carrier (secondary CC) of the mobile station UE
is in a de-activated state in a corresponding subframe. The
secondary CC corresponds to the second carrier in the above
description.
When the secondary CC of the mobile station UE is in a de-activated
state in the subframe (step S402:Yes), the radio base station eNB
determines whether the subframe is a gap section for measuring the
secondary CC of the mobile station UE in step S404. Instead of
determining whether the subframe is a gap section for measuring the
secondary CC, the radio base station eNB may determine whether the
subframe is the first section or the fourth section shown in FIG.
14.
If the subframe is a gap section for measuring the secondary CC of
the mobile station UE (step S404:YES), the radio base station eNB
does not perform communication on the primary component carrier
(primary CC) for the mobile station UE in the subframe (step S406).
That is, the radio base station eNB does not perform downlink
transmission and uplink reception on the primary component carrier
(primary CC) for the mobile station UE in the subframe.
Alternatively, the radio base station eNB may perform scheduling
such that downlink transmission or uplink reception on the primary
CC for the UE does not occur. The primary CC corresponds to the
first carrier in the above-mentioned description.
When the secondary CC of the mobile station UE is not in the
de-activated state in the subframe (step S402:NO), or when the
secondary CC of the mobile station UE is in a de-activated state in
the subframe and the subframe is not a gap section for the
secondary CC of the mobile station UE (step S404:NO), the radio
base station eNB performs communication on the primary CC for the
mobile station UE in the subframe (step S408). Alternatively, the
radio base station eNB may perform downlink or uplink scheduling
for the primary CC on the UE.
A communication control method in the mobile station UE according
to the present embodiment is described with reference to FIG.
15.
In step S502, the mobile station UE determines whether the second
carrier is in a de-activated state in a corresponding subframe. The
second carrier may be the secondary component carrier.
When the second carrier is in a de-activated state in the subframe
(step S502:YES), the mobile station UE determines whether the
subframe is the second section of the measurement section for SCC
in step 504.
When the subframe is the second section of the measurement section
for SCC (step S504:YES), the mobile station UE performs measurement
of the second carrier and does not perform communication on the
second carrier (step S506). That is, the mobile station UE performs
cell search, measurement, radio link monitoring or the like on the
second carrier in the subframe, but does not perform uplink
transmission or downlink reception on the second carrier in the
subframe.
When the subframe is not the second section of the measurement
section for SCC (step S504:No), the mobile station determines
whether the subframe is the third section of the measurement
section for SCC (step S508)
When the subframe is the third section of the measurement section
for SCC (step S508:YES), the mobile station UE performs measurement
of the second carrier in the subframe (step S510). That is, the
mobile station UE transmits an uplink signal and receives a
downlink signal using the second carrier in the subframe.
When the subframe is not the third section of the measurement
section for SCC in step S508 (step S508:No), the mobile station UE
does not perform either measurement or communication on the second
carrier in the subframe. The mobile station UE performs
communication on the primary CC (step S512).
When the second carrier is not in a de-activated state in the
subframe (step 502:NO), the mobile station UE performs
communication on the second carrier and performs measurement of the
second carrier at a proper frequency (step S514).
A communication control method in the radio base station eNB
according to the present embodiment is described with reference to
FIG. 16.
In step S602, the radio base station eNB determines whether the
second carrier is in a de-activated state in a corresponding
subframe. The second carrier may be the secondary component
carrier.
When the second carrier is in a de-activated state in the subframe
(step S602:YES), the radio base station eNB determines whether the
subframe is the third section of the measurement section for SCC in
step 604.
When the subframe is the third section of the measurement section
for SCC (step S604:YES), the radio base station eNB performs
communication on the second carrier in the subframe (step S606).
That is, the radio base station eNB performs uplink reception and
downlink transmission on the second carrier.
When the subframe is not the third section of the measurement
section for SCC (step S604:No), the radio base station eNB does not
perform communication on the second carrier in the subframe (step
S608).
When the second carrier is not in a de-activated state in the
subframe (step 602:NO), the radio base station eNB performs
communication on the second carrier (step S610).
In the above-mentioned example, operation is described in which,
when the second carrier is not activated, the mobile station UE and
the radio base station eNB perform communication on the second
carrier in the third section shown in FIG. 14 or the section
between the two gap sections shown in FIGS. 6-9. Instead of this
operation, when the second carrier is not activated, operation may
be adopted in which communication is not performed in the second
carrier. In this case, the mobile station UE may perform
measurement of the second carrier as operation on the second
carrier in the gap section shown in FIG. 14 or FIGS. 6-9.
In the above-mentioned example, as an operation of the mobile
station UE and the radio base station eNB, operation is described
in which, in a state where a measurement gap for measuring the
second carrier that is the secondary component carrier is set, when
the secondary component carrier is activated, the measurement gap
is neglected, on the other hand, when the secondary component
carrier is not activated, communication of the first carrier is
stopped in the gap section of the measurement gap. Instead of this
operation, an operation may be adopted in which, in a state where a
measurement gap for measuring the second carrier that is the
secondary component carrier is set, when the secondary component
carrier is not in a DRX state, the measurement gap is neglected, on
the other hand, when the secondary component carrier is in a DRX
state, communication of the first carrier is stopped in the gap
section of the measurement gap.
The measurement gap and on-duration of the DRX control may be the
same. That is, the present embodiment is not limited to the cases
where the secondary component carrier is in an activated
state/where the secondary component carrier is in a de-activated
state, and the present embodiment may be applied to the cases where
the secondary component carrier is in a non-DRX state/where the
secondary component carrier is in a DRX state. In this case, the
sections B1 and B2 shown in FIG. 5 may correspond to the
on-duration, and sections, in which the mobile station UE switches
the center frequency of the receiver, that accompany before and
after the on-duration. Alternatively, the two divided gap sections
shown in FIG. 6 may correspond to the sections, in which the mobile
station UE switches the center frequency of the receiver, that
accompany before and after the on-duration, and the section between
the two divided gap sections may correspond to the on-duration.
Alternatively, the present embodiment is not limited to the case
where the secondary component carrier is in the activated state or
in the de-activated state, but may be applied to the case where the
secondary component carrier is in a state in which communications
are always performed or in a state in which communications are
intermittently performed. For example, the state in which
communications are intermittently performed may include a state
where monitoring of control signals, cell search, or measurement is
intermittently performed and usual data communications are not
performed.
The state which is not in the DRX state may be called a non-DRX
state. The Non-DRX state may be a state in which a parameter
associated with discontinuous reception control is not configured,
a state in which a parameter associated with discontinuous
reception control is configured and a timer for discontinuous
reception control is in an operating state, a state in which a
parameter associated with discontinuous reception control is
configured and a scheduling request is in a pending state, a state
in which a parameter associated with discontinuous reception
control is configured and a timing for uplink HARQ retransmission
is provided, or a state in which a parameter associated with
discontinuous reception control is configured and a downlink
control signal for initial transmission destined for the own
station is not received after a random access response for a
specified preamble is received. In addition, the DRX state may be a
state other than the Non-DRX state.
Effects of a mobile station UE, a radio base station eNB, a
communication control method in accordance with this embodiment are
described below.
As mentioned above, according to the present embodiment, in a state
where the measurement gap is set for measuring the second carrier
that is the secondary component carrier, when the secondary
component carrier is activated, deterioration of throughput due to
the measurement gap is avoided by neglecting the measurement gap,
on the other hand, when the secondary component carrier is not
activated, an event can be avoided in which data to be transmitted
and received is lost in the mobile station UE by performing
measurement of the second carrier while stopping the communication
of the first carrier in consideration of the measurement gap.
Although transition between the activated state and the
de-activated state is performed in the MAC layer for performing
control quickly, setting of the measurement gap is performed in the
RRC layer that is an upper layer of the MAC layer. Therefore, if
setting and release of the measurement gap is performed according
to transition between the activated state and the de-activated
state, the advantage of the MAC layer control in which control is
performed quickly disappears. That is, setting of the measurement
gap needs to be performed irrespective of whether the state is in
the activated state or the de-activated state.
The operations in the mobile station UE and the radio base station
eNB as described above may be applied to a mobile station, a radio
base station, and a control station in a system other than the
LTE-Advanced system. For example, the operations may be applied to
a mobile station, a radio base station, and a control station in an
LTE system, a WCDMA system, a CDMA 2000 system, or a WiMAX
system.
The operations in the mobile station UE and the radio base station
eNB as described above may be implemented as hardware, a software
module executed by a processor, or a combination of them.
The software module may be stored in a storage medium of any type,
such as a random access memory (RAM), a flash memory, a read-only
memory (ROM), an erasable programmable ROM (EPROM), an
electronically erasable and programmable ROM (EEPROM), a register,
a hard disk, a removable disk, or a CD-ROM.
The storage medium is connected to a processor in order for the
processor to read and write information in the storage medium.
Alternatively, the storage medium may be integrated in the
processor. Alternatively, the storage medium and the processor may
be included in an application specific integrated circuit (ASIC).
The ASIC may be included in a mobile station UE and a radio base
station eNB. Alternatively, the storage medium and the processor
may be included in a mobile station UE and a radio base station eNB
as a discrete component.
While the embodiments of the present invention have been described
in detail, a person skilled in the art clearly understands that the
present invention is not limited to the embodiments described in
the specification. The present invention can be modified or changed
without departing from the intention and the scope of the present
invention defined by the claims. Thus, the specification is
provided for the purpose of illustration and should not be treated
as limiting the present invention. Thus, the specification is
provided for the purpose of illustration and should not be treated
as limiting the present invention.
The present international application claims priority based on
Japanese patent application No. 2010-118834, filed in the JPO on
May 24, 2010, and the entire contents of the Japanese patent
application No. 2010-118834 are incorporated herein by
reference.
DESCRIPTION OF NOTATIONS
UE mobile station 102 first communicating unit 102A first downlink
receiving unit 102B first uplink transmitting unit 102C first
measuring unit 104A second downlink receiving unit 104E second
uplink transmitting unit 104C second measuring unit 106
Activation/De-activation control unit 108 gap control unit eNB
radio base station 202A first downlink transmitting unit 202B first
uplink receiving unit 204A second downlink transmitting unit 204B
second uplink receiving unit 206 Activation/De-activation control
unit 208 gap control unit
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