U.S. patent application number 14/428098 was filed with the patent office on 2015-08-20 for communication control device, program, communication control method, and terminal device.
This patent application is currently assigned to SONY CORPORATION. The applicant listed for this patent is SONY CORPORATION. Invention is credited to Hiroaki Takano.
Application Number | 20150237545 14/428098 |
Document ID | / |
Family ID | 50626983 |
Filed Date | 2015-08-20 |
United States Patent
Application |
20150237545 |
Kind Code |
A1 |
Takano; Hiroaki |
August 20, 2015 |
COMMUNICATION CONTROL DEVICE, PROGRAM, COMMUNICATION CONTROL
METHOD, AND TERMINAL DEVICE
Abstract
There is provided a communication control device including an
acquisition unit configured to acquire system information of a
frequency band that is used in a small cell that is partially or
entirely overlapped by a macro cell, and a control unit configured
to control downlink transmission of the system information in the
macro cell. The control unit notifies a terminal device positioned
within the macro cell of radio resource that is used in the
downlink transmission.
Inventors: |
Takano; Hiroaki; (Saitama,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SONY CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
SONY CORPORATION
Tokyo
JP
|
Family ID: |
50626983 |
Appl. No.: |
14/428098 |
Filed: |
July 25, 2013 |
PCT Filed: |
July 25, 2013 |
PCT NO: |
PCT/JP2013/070210 |
371 Date: |
March 13, 2015 |
Current U.S.
Class: |
370/331 |
Current CPC
Class: |
H04W 36/0072 20130101;
H04W 36/22 20130101; H04W 48/12 20130101; H04W 72/0453 20130101;
H04W 48/10 20130101; H04W 72/0426 20130101; H04W 16/32 20130101;
H04W 84/045 20130101 |
International
Class: |
H04W 36/00 20060101
H04W036/00; H04W 72/04 20060101 H04W072/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 2012 |
JP |
2012-238813 |
Claims
1. A communication control device comprising: an acquisition unit
configured to acquire system information of a frequency band that
is used in a small cell that is partially or entirely overlapped by
a macro cell; and a control unit configured to control downlink
transmission of the system information in the macro cell, wherein
the control unit notifies a terminal device positioned within the
macro cell of radio resource that is used in the downlink
transmission.
2. The communication control device according to claim 1, wherein
the radio resource is resource of a frequency band that is used in
the macro cell and the resource that is not used in transmission of
the system information of the frequency band.
3. The communication control device according to claim 2, wherein
the radio resource is not used in transmission of system
information of a frequency band that is used in another small cell
either.
4. The communication control device according to claim 2, wherein
the radio resource is resource of a physical downlink shared
channel.
5. The communication control device according to claim 2, wherein
updating of the system information of the frequency band that is
used in the small cell is notified of independently of updating of
the system information of the frequency band that is used in the
macro cell.
6. The communication control device according to claim 5, wherein
updating of the system information of the frequency band that is
used in the small cell is also notified of independently of
updating of system information of a frequency band that is used in
another small cell.
7. The communication control device according to claim 5, wherein,
for the updating of the system information of the frequency band
that is used in the small cell, information pertaining to the
updating is notified of along with the radio resource.
8. The communication control device according to claim 2, wherein
the radio resource is notified of using radio resource for
notification that has a predetermined positional relation with
another radio resource that is used in transmission of a
predetermined information block included in the system information
of the frequency band used in the macro cell.
9. The communication control device according to claim 8, wherein
the another radio resource is resource positioned within a
predetermined range in a time direction and a frequency
direction.
10. The communication control device according to claim 8, wherein
the predetermined positional relation is a positional relation that
has a predetermined offset with the another radio resource in a
time direction or a frequency direction.
11. The communication control device according to claim 2, wherein
the radio resource is notified of through signaling to a terminal
device that is in a connection state in the macro cell.
12. The communication control device according to claim 2, wherein
the control unit also notifies small cell identification
information for identifying the small cell along with the radio
resource.
13. The communication control device according to claim 1, wherein
the system information of the frequency band that is used in the
small cell is not transmitted in the small cell.
14. A program causing a computer to function as: an acquisition
unit configured to acquire system information of a frequency band
that is used in a small cell that is partially or entirely
overlapped by a macro cell; and a control unit configured to
control downlink transmission of the system information in the
macro cell, wherein the control unit notifies a terminal device
positioned within the macro cell of radio resource that is used in
the downlink transmission.
15. A communication control method comprising: acquiring system
information of a frequency band that is used in a small cell that
is partially or entirely overlapped by a macro cell; controlling
downlink transmission of the system information in the macro cell;
and notifying a terminal device positioned within the macro cell of
radio resource that is used in the downlink transmission.
16. A communication control device comprising: a generation unit
configured to generate system information of a frequency band that
is used in a small cell that is partially ore entirely overlapped
by a macro cell; and a provision unit configured to provide the
system information to the device that is a device controlling
downlink transmission of the system information in the macro cell
and notifying a terminal device positioned within the macro cell of
radio resource that is used in the downlink transmission.
17. A program causing a computer to function as: a generation unit
configured to generate system information of a frequency band that
is used in a small cell that is partially or entirely overlapped by
a macro cell; and a provision unit configured to provide the system
information to a device that is a device controlling downlink
transmission of the system information in the macro cell and
notifying a terminal device positioned within the macro cell of
radio resource that is used in the downlink transmission.
18. A communication control method comprising: generating system
information of a frequency band that is used in a small cell that
is partially or entirely overlapped by a macro cell; and providing
the system information to a device that is a device controlling
downlink transmission of the system information in the macro cell
and notifying a terminal device positioned within the macro cell of
radio resource that is used in the downlink transmission.
19. A terminal device comprising: a wireless communication unit
configured to receive system information of a frequency band that
is used in a small cell that is partially or entirely overlapped by
a macro cell when the terminal device is positioned within the
macro cell; and an acquisition unit configured to acquire
information transmitted using radio resource as the system
information when the terminal device is positioned within the macro
cell and the radio resource that is used in downlink transmission
of the system information is notified of.
20. A communication control method comprising: receiving system
information of a frequency band that is used in a small cell that
is partially or entirely overlapped by a macro cell when a terminal
device is positioned within the macro cell; and acquiring
information transmitted using radio resource as the system
information when the terminal device is positioned within the macro
cell and the radio resource that is used in downlink transmission
of the system information is notified of.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a communication control
device, a program, a communication control method, and a terminal
device.
BACKGROUND ART
[0002] Currently, increasing data traffic in cellular systems
caused by spread of smartphones is a concern. For this reason,
expanding communication capacities of the cellular systems become
more and more important for each cellular business operator. In
order to expand the communication capacities, the business
operators dispose, for example, small cells such as pico cells and
femto cells within macro cells. Accordingly, the business operators
can gain more communication capacities from advantages of cell
splitting.
[0003] Generally in a macro cell, system information of the macro
cell is transmitted from a base station of the macro cell. Likewise
in a small cell, system information of the small cell is
transmitted from a base station of the small cell. Technologies
pertaining to transmission methods of such system information of
small cells have also been proposed.
[0004] For example, Patent Literature 1 discloses a technology in
which a base station of a femto cell transmits subframes that
constitute a subframe set including a plurality of kinds of
subframes and are included in the subframe set in a predetermined
order, in order to prevent deterioration in performance of a
system.
CITATION LIST
Patent Literature
[0005] Patent Literature 1: JP 2012-523745T
SUMMARY OF INVENTION
Technical Problem
[0006] According to the existing techniques for transmission of
system information including the technique disclosed in Patent
Literature 1, however, system information of small cells is
transmitted only by base stations of the small cells. For this
reason, an area in which a terminal device can receive the system
information of the small cells is limited. Thus, there may be cases
in which the terminal device has not acquired the system
information of the small cells when it has just entered or come
close to the small cells. As a result, spending much time in
connection of the terminal device in the small cells is a concern.
For example, spending much time in, for example, specifying a cell
in a cell search, receiving system information thereof after the
cell search, and the like is a concern. Due to the fact that a
small cell is smaller than a macro cell, the frequency of the
terminal device entering and exiting a small cell is considered to
be higher than the frequency of the terminal device entering and
exiting a macro cell, and thus spending much time as described
above is not favorable.
[0007] Therefore, it is desirable to provide a mechanism in which a
time taken for connection of a terminal device in a small cell can
be further shortened.
Solution to Problem
[0008] According to the present disclosure, there is provided a
communication control device including an acquisition unit
configured to acquire system information of a frequency band that
is used in a small cell that is partially or entirely overlapped by
a macro cell, and a control unit configured to control downlink
transmission of the system information in the macro cell. The
control unit notifies a terminal device positioned within the macro
cell of radio resource that is used in the downlink
transmission.
[0009] In addition, according to the present disclosure, there is
provided a program causing a computer to function as an acquisition
unit configured to acquire system information of a frequency band
that is used in a small cell that is partially or entirely
overlapped by a macro cell, and a control unit configured to
control downlink transmission of the system information in the
macro cell. The control unit notifies a terminal device positioned
within the macro cell of radio resource that is used in the
downlink transmission.
[0010] In addition, according to the present disclosure, there is
provided a communication control method including acquiring system
information of a frequency band that is used in a small cell that
is partially or entirely overlapped by a macro cell, controlling
downlink transmission of the system information in the macro cell,
and notifying a terminal device positioned within the macro cell of
radio resource that is used in the downlink transmission.
[0011] According to the present disclosure, there is provided a
communication control device including a generation unit configured
to generate system information of a frequency band that is used in
a small cell that is partially ore entirely overlapped by a macro
cell, and a provision unit configured to provide the system
information to the device that is a device controlling downlink
transmission of the system information in the macro cell and
notifying a terminal device positioned within the macro cell of
radio resource that is used in the downlink transmission.
[0012] In addition, according to the present disclosure, there is
provided a program causing a computer to function as a generation
unit configured to generate system information of a frequency band
that is used in a small cell that is partially or entirely
overlapped by a macro cell, and a provision unit configured to
provide the system information to a device that is a device
controlling downlink transmission of the system information in the
macro cell and notifying a terminal device positioned within the
macro cell of radio resource that is used in the downlink
transmission.
[0013] In addition, according to the present disclosure, there is
provided a communication control method including generating system
information of a frequency band that is used in a small cell that
is partially or entirely overlapped by a macro cell, and providing
the system information to a device that is a device controlling
downlink transmission of the system information in the macro cell
and notifying a terminal device positioned within the macro cell of
radio resource that is used in the downlink transmission.
[0014] According to the present disclosure, there is provided a
terminal device including a wireless communication unit configured
to receive system information of a frequency band that is used in a
small cell that is partially or entirely overlapped by a macro cell
when the terminal device is positioned within the macro cell, and
an acquisition unit configured to acquire information transmitted
using radio resource as the system information when the terminal
device is positioned within the macro cell and the radio resource
that is used in downlink transmission of the system information is
notified of.
[0015] In addition, according to the present disclosure, there is
provided a communication control method including receiving system
information of a frequency band that is used in a small cell that
is partially or entirely overlapped by a macro cell when a terminal
device is positioned within the macro cell, and acquiring
information transmitted using radio resource as the system
information when the terminal device is positioned within the macro
cell and the radio resource that is used in downlink transmission
of the system information is notified of.
Advantageous Effects of Invention
[0016] According to the present disclosure as described above, it
is possible to further shorten a time taken for connection of a
terminal device in a small cell.
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is an illustrative diagram for describing an example
of a scenario in which a macro cell and a small cell use different
frequency bands.
[0018] FIG. 2 is an illustrative diagram for describing an example
of PCCs of each UE.
[0019] FIG. 3 is an illustrative diagram for describing a physical
broadcast channel (PBCH) on which an MIB is transmitted.
[0020] FIG. 4 is an illustrative diagram for describing subframes
transmitted by SIB 1.
[0021] FIG. 5 is an illustrative diagram showing an example of a
schematic configuration of a wireless communication system
according to an embodiment.
[0022] FIG. 6 is a block diagram showing an example of a
configuration of a macro eNodeB according to an embodiment.
[0023] FIG. 7 is an illustrative diagram for describing an example
of information transmitted for notification of radio resource used
in transmission of system information of a pico cell side.
[0024] FIG. 8 is an illustrative diagram for describing an example
of correspondences between LPSI and radio resource.
[0025] FIG. 9 is a block diagram showing an example of a
configuration of a pico eNodeB according to an embodiment.
[0026] FIG. 10 is a block diagram showing an example of a
configuration of a UE according to an embodiment.
[0027] FIG. 11 is a sequence diagram showing an example of a
schematic flow of a communication control process according to an
embodiment.
[0028] FIG. 12 is an illustrative diagram for describing an example
of a position of radio resource used in transmission of SIB 1.
[0029] FIG. 13 is an illustrative diagram for describing a first
example of radio resource used in transmission of LPSI according to
a first modified example of an embodiment.
[0030] FIG. 14 is an illustrative diagram for describing a first
example of radio resource used in transmission of LPSI according to
a second modified example of an embodiment.
[0031] FIG. 15 is an illustrative diagram for describing a first
example of radio resource used in transmission of LPSI according to
a third modified example of an embodiment.
[0032] FIG. 16 is a sequence diagram showing an example of a
schematic flow of a communication control process according to the
first modified example of an embodiment.
[0033] FIG. 17 is an illustrative diagram for describing an example
of information transmitted for notification of updating of system
information of a pico cell side.
[0034] FIG. 18 is an illustrative diagram for describing an example
of correspondences between pico system information and information
transmitted to notify of updating of the pico system
information.
[0035] FIG. 19 is a sequence diagram showing an example of a
schematic flow of a communication control process according to a
second modified example of an embodiment.
DESCRIPTION OF EMBODIMENTS
[0036] Hereinafter, preferred embodiments of the present disclosure
will be described in detail with reference to the appended
drawings. Note that, in this specification and the appended
drawings, structural elements that have substantially the same
function and structure are denoted with the same reference
numerals, and repeated explanation of these structural elements is
omitted.
[0037] Note that description will be provided in the following
order.
[0038] 1. Preface [0039] 1.1. Wireless communication technology of
the 3GPP [0040] 1.2. Technical problem
[0041] 2. Schematic configuration of a wireless communication
system
[0042] 3. Configurations of respective devices [0043] 3.1.
Configuration of a macro eNodeB [0044] 3.2. Configuration of a pico
eNodeB [0045] 3.3. Configuration of a UE
[0046] 4. Process flow
[0047] 5. Modified examples [0048] 5.1. First modified example
[0049] 5.1.1. Overview [0050] 5.1.2. Configurations of respective
devices [0051] 5.1.3. Process flow [0052] 5.2. Second modified
example [0053] 5.2.1. Overview [0054] 5.2.2. Configurations of
respective devices [0055] 5.2.3. Process flow
[0056] 6. Conclusion
1. PREFACE
[0057] First, a wireless communication technology of the 3.sup.rd
Generation Partnership Project (3GPP) and technical challenges
thereof will be described.
1.1. Wireless Communication Technology of the 3GPP
[0058] Hereinafter, the wireless communication technology of the
3GPP will be described with reference to FIGS. 1 to 4.
(Small Cell of Release 10)
[0059] There is a mention in Release 10 as well as Release 11 of
the 3GPP of small cells (to be specific, pico cells). In Release 10
and Release 11, a base station is referred to as an eNodeB, and
particularly, an eNodeB of a macro cell is referred to as a macro
eNodeB, and an eNodeB of a pico cell is referred to as a pico
eNodeB.
[0060] A pico cell is partially or entirely overlapped by a macro
cell, and for example, a macro eNodeB and a pico eNodeB use the
same frequency band. Such a network is referred to as a
heterogeneous network (Het-Net). Reducing interference between a
macro eNodeB and a pico eNodeB in a Het-Net is an important task,
and thus the 3GPP has been vigorously discussed a technology for
reducing such interference. For example, providing a subframe that
is called an almost blank subframe (ABS) in which most
transmissions stop on a macro cell (macro eNodeB) side and the like
have been reviewed.
(Small Cell that is Assumed in Release 12)
[0061] On the other hand, a scenario in which a macro eNodeB and a
pico eNodeB use different frequency bands is expected to be
reviewed as a scenario of Release 12. Hereinbelow, this point will
be described in more detail with reference to FIG. 1.
[0062] FIG. 1 is an illustrative diagram for describing an example
of the scenario in which a macro cell and a small cell use
different frequency bands. Referring to FIG. 1, a macro cell 10 and
a macro eNodeB 11 are shown. In addition, a pico cell 20 that is
entirely overlapped by the macro cell 10 and a pico eNodeB 21 are
shown. Furthermore, a user equipment (UE) 31 that communicates with
the macro eNodeB and the pico eNodeB is shown. On such a network,
for example, the macro eNodeB 11 performs wireless communication
with the UE 31 using a frequency band of the 2 GHz band within the
macro cell 10. In addition, for example, the pico eNodeB 21
performs wireless communication with the UE 31 using a frequency
band of the 5 GHz band within the pico cell 20.
(Carrier Aggregation of Release 10)
[0063] Component Carrier
[0064] In carrier aggregation of Release 10, up to five component
carriers (CCs) are bundled and used in a UE. Each CC is a bandwidth
of up to 20 MHz. In carrier aggregation, CCs continuing in a
frequency direction are used in some cases and CCs separated in the
frequency direction are used in some cases. In carrier aggregation,
the CCs to be used can be set for each UE.
[0065] Primary CC and Secondary CC
[0066] In carrier aggregation, one of the plurality of CCs used by
the UE is a special CC. The one special CC is referred to as a
primary component carrier (PCC). Of the plurality of CCs, the
remaining CCs are referred to as secondary component carriers
(SCCs). The PCC can differ for each UE. This point will be
described more specifically below with reference to FIG. 2.
[0067] FIG. 2 is an explanatory diagram illustrating an example of
the PCC of each UE. A UE 31a, a UE 31b, and five CCs 1 to 5 are
illustrated in FIG. 2. In this example, the UE 31a uses two CCs,
the CC 1 and the CC 2. The UE 31a uses the CC 2 as the PCC. On the
other hand, the UE 31b uses two CCs, the CC 2 and the CC 4. The UE
31b uses the CC 4 as the PCC. In this way, each UE can use a
different CC as the PCC.
[0068] Since the PCC is the most important CC among the plurality
of CCs, the CC for which communication quality is the stablest is
preferable. Which CC is used as the PCC actually depends the way in
which they are installed.
[0069] The CC with which a UE initially establishes connection is
the PCC in the UE. The SCC is added to the PCC. That is, the PCC is
a main frequency band and the SCC is an auxiliary frequency band.
The SCC is changed by deleting the existing SCC and adding a new
SCC. The PCC is changed in an inter-frequency handover sequence of
the related art. In carrier aggregation, a UE may not use only the
SCC, but necessarily uses one PCC.
[0070] The PCC is also referred to as a primary cell. The SCC is
also referred to as a secondary cell.
(System Information)
[0071] System information includes a master information block (MIB)
and a system information block (SIB). An MIB includes vital
information for receiving data in a first stage such as a bandwidth
to be used, a system frame number (SFN), a configuration of a
hybrid ACK, and the like. In addition, an SIB includes other system
information. Information included in an MIB is more important
information than information included in an SIB.
[0072] An MIB is transmitted on a physical broadcast channel
(PBCH). Hereinbelow, a PBCH on which an MIB is transmitted will be
described in detail.
[0073] FIG. 3 is an illustrative diagram for describing a physical
broadcast channel (PBCH) on which an MIB is transmitted. Referring
to FIG. 3, radio resource of a frequency band in a #0 subframe are
shown. The #0 subframe is one of 10 subframes (#0 to #9 subframes)
included in a 10 ms radio frame (Radio Frame). Referring to FIG. 3,
the subframe includes two slots. In addition, each slot includes 7
OFDM symbols. 1 to 3 OFDM symbols of the first slot are physical
downlink control channels (PDCCH), and 4 to 7 OFDM symbols of the
first slot and the second slot are physical downlink shared
channels (PDSCH). In addition, particularly in the #0 subframe, a
PBCH is positioned in the range of 72 subcarriers at the center of
a frequency band in the frequency direction and 1 to 4 OFDM symbols
of the second slot in the time direction. In other words, a PBCH is
disposed over six resource blocks. An MIB is transmitted on this
PBCH.
[0074] In addition, an SIB is transmitted on a physical downlink
shared channel (Physical Downlink Shared Channel). Particularly, an
SIB 1 of SIBs is transmitted in a #5 subframe of a radio frame
whose SFN is an even number. This will be described in detail with
reference to FIG. 4.
[0075] FIG. 4 is an illustrative diagram for describing a subframe
in which the SIB 1 is transmitted. Referring to FIG. 4, two
consecutive radio frames, i.e., a radio frame whose SFN is an even
number and a radio frame whose SFN is an odd number are shown. In
addition, the SIB 1 is transmitted in the #5 subframe of the radio
frame whose SFN is an even number. On the other hand, the SIB 1 is
not transmitted in the radio frame whose SFN is an odd number. The
SIB 1 is transmitted in a fixed subframe as above.
[0076] Note that an MIB indicates at which position in the
frequency direction of the #5 subframe of the radio frame whose SFN
is an even number the SIB 1 is transmitted. For this reason, the
SIB 1 is not transmitted completely at a fixed position, but
transmitted at a semi-fixed position, different from an MIB. Note
that a position in the time direction (i.e., an OFDM symbol) in the
#5 subframe in which the SIB 1 is transmitted is fixed.
[0077] In addition, SIBs 2 to 11 among SIBs are not entirely
transmitted in a fixed subframe, like the SIB 1. The SIBs 2 to 11
are transmitted using the radio resource represented by the SIB
1.
(Paging)
[0078] In LTE, there are an RRC connected (RRC_Connected) mode and
an RRC idle (RRC_Idle) mode as modes of a UE.
[0079] When the mode of a UE is the RRC connected mode, connection
between the UE and an eNodeB is established, and thereby
transmission and reception of uplink signals and downlink signals
are possible.
[0080] On the other hand, when the mode of the UE is the RRC idle
mode, the eNodeB does not have information of the UE, and a
tracking area in which the UE is present is registered in a
mobility management entity (MME). An MME is a node that is
wire-connected to the eNodeB in an S1-MME interface. A tracking
area is an area that includes dozens to hundreds of cells close to
each other.
[0081] When there is an incoming call to the UE, the MME performs
calling-out at a paging channel in all cells included in the
tracking area of the UE. In other words, the UE in the RRC idle
mode monitors the paging channel, and when there is an incoming
call to the UE, the mode of the device transitions from the RRC
idle mode to the RRC connection mode.
[0082] The UE in the RRC idle mode performs power saving such as
stopping a clock of hardware, stopping power supply, or the like in
order to reduce power consumption except for the time at which
information is transmitted on the paging channel. In addition, when
the time at which information is transmitted on the paging channel
arrives, the UE turns the power on, receives the information on the
paging channel, and then performs power saving again after the
reception.
(Updating of System Information)
[0083] Updating of system information (System Information Update)
is notified of on the paging channel. In addition, updating of
system information is also notified of by the SIB 1 of the system
information.
(System Information in Carrier Aggregation and Updating
Thereof)
[0084] In carrier aggregation, system information is provided by
all component carriers (CC). In addition, since the SIB 1 is
transmitted by all CCs, updating of the system information is
notified of by all CCs. A UE applied to carrier aggregation,
however, can be aware of updating of the system information of all
CCs by monitoring only the PCC.
1.2. Technical Challenge
[0085] Next, a technical challenge that is also relevant to the
above-described technology will be described.
[0086] Generally in a macro cell, system information of the macro
cell is transmitted by a macro eNodeB. In addition, likewise in a
pico cell, system information of the pico cell is transmitted by a
pico eNodeB. A technology relating to a transmission method of
system information of such a small cell has also been proposed.
[0087] JP 2012-523745A, for example, discloses a technology in
which a base station of a femto cell transmits subframes that
constitutes a subframe set that includes a plurality kinds of
subframes and are included in the subframe set in a predetermined
order to prevent deterioration in performance of a system.
[0088] According to the transmission method of system information
of the related art described above, however, system information of
a pico cell is transmitted entirely by a pico eNodeB. For this
reason, due to low transmission electric power, a high frequency
band, or the like, for example, an area in which a UE can receive
the system information of the pico cell is limited. Thus, there are
also cases in which the UE has not yet acquired the system
information of the pico cell when the UE has just entered or come
close to the pico cell. For example, the UE can fail to acquire the
system information of the pico cell when the UE enters the pico
cell at a high speed. As a result, spending much time in connection
of a UE in a small cell is a concern. A UE, for example, the UE,
specifies a pico cell among all pico cell candidates in a cell
search based on a primary synchronization signal (PSS) and a
secondary synchronization signal (SSS), and thus specification of a
cell can require much time. In addition, since the UE newly
receives system information after the cell search, for example, the
reception of the system information can take much time as well. The
frequency of a UE entering and exiting a small cell is higher than
the frequency of the UE entering and exiting a macro cell due to
the fact that a small cell is smaller than a macro cell, and thus
spending much time as described above is not favorable.
[0089] Therefore, embodiments of the present disclosure enable a
time taken for connection of a UE in a pico cell to be further
shortened. Hereinbelow, details thereof will be described in
<<<2. Schematic configuration of a wireless communication
system>>>, <<<3. Configurations of respective
devices>>>, <<<4. Process flow>>>, and
<<<5. Modified examples>>>.
2. SCHEMATIC CONFIGURATION OF A WIRELESS COMMUNICATION SYSTEM
[0090] A schematic configuration of a wireless communication system
according to an embodiment of the present disclosure will be
described with reference to FIG. 5. FIG. 5 is an illustrative
diagram showing an example of the schematic configuration of the
wireless communication system according to the present embodiment.
The wireless communication system is a wireless communication
system based on, for example, LTE. Referring to FIG. 5, the
wireless communication system includes a macro eNodeB 100 of the
macro cell 10 and a pico eNodeB 200 of the pico cell 20, and a UE
300.
[0091] The macro eNodeB 100 wirelessly communicates with the UE 300
within the macro cell 10. As an example, a frequency band of the 2
MHz band is used within the macro cell 10 for wireless
communication between the macro eNodeB 100 and the UE 300.
[0092] The pico eNodeB 200 wirelessly communicates with the UE 300
within the pico cell 20. The pico cell 20 is partially or entirely
overlapped by the macro cell 10. Within the pico cell 20, for
example, a different frequency band from the frequency band used in
the macro cell 10 is used. To be specific, a frequency band used
within the pico cell 20, for example, is a higher frequency band
than the frequency band used within the macro cell 10. As an
example, a frequency band of the 5 MHz band is used in wireless
communication between the pico eNodeB 200 and the UE 300 within the
pico cell 20.
[0093] The UE 300 wirelessly communicates with the macro eNodeB 100
within the macro cell 10. In addition, the UE 300 wirelessly
communicates with the pico eNodeB 200 within the pico cell 20.
3. CONFIGURATIONS OF RESPECTIVE DEVICES
[0094] Next, examples of respective configurations of the macro
eNodeB 100, the pico eNodeB 200, and the UE 300 will be described
with reference to FIGS. 6 to 10.
3.1. Configuration of a Macro eNodeB
[0095] First, an example of a configuration of the macro eNodeB 100
will be described with reference to FIGS. 6 to 8. FIG. 6 is a block
diagram showing the example of the configuration of the macro
eNodeB 100 according to the present embodiment. Referring to FIG.
6, the macro eNodeB 100 is provided with an antenna unit 110, a
wireless communication unit 120, a network communication unit 130,
a storage unit 140, and a control unit 150.
(Antenna Unit 110)
[0096] The antenna unit 110 receives a radio signal and outputs the
received radio signal to the radio communication unit 120. The
antenna unit 110 transmits a transmission signal output by the
radio communication unit 120.
(Wireless Communication Unit 120)
[0097] The wireless communication unit 120 wirelessly communicates
with the UE 300 that is positioned within the macro cell 10. As an
example, the wireless communication unit 120 wirelessly
communicates with the UE 300 using a frequency band of the 2 MHz
band. The wireless communication unit 120 includes, for example, a
radio frequency (RF) circuit and other circuits.
(Network Communication Unit 130)
[0098] The network communication unit 130 communicates with other
devices. For example, the network communication unit 130
communicates with the pico eNodeB 200. The network communication
unit 130 includes, for example, a communication interface for any
type of wired communication.
(Storage Unit 140)
[0099] The storage unit 140 stores programs and data for operations
of the macro eNodeB 100. The storage unit 140 includes a storage
medium, for example, a hard disk, a semiconductor memory, or the
like.
(Control Unit 150)
[0100] The control unit 150 provides various functions of the macro
eNodeB 100. For example, the control unit 150 corresponds to a
processor such as a CPU or a DSP, and provides the various
functions by causing programs stored in the storage unit 140 or
other storage media to be executed. The control unit 150 includes
an information acquisition unit 151 and a communication control
unit 153.
(Information Acquisition Unit 151)
[0101] The information acquisition unit 151 acquires system
information of a frequency band that is used in the pico cell 20
(which will be referred to hereinafter as "pico system
information"). When, for example, the network communication unit
130 receives pico system information transmitted by the pico eNodeB
200, the information acquisition unit 151 acquires the pico system
information.
(Communication Control Unit 153)
[0102] The communication control unit 153 controls wireless
communication within the macro cell 10.
[0103] Transmission of System Information of a Pico Cell Side
[0104] Particularly in the present embodiment, the communication
control unit 153 controls downlink transmission of the pico system
information in the macro cell 10. For example, the wireless
communication unit 153 causes the wireless communication unit 120
to perform downlink transmission of the pico system information in
the macro cell 10. In other words, the wireless communication unit
153 causes the wireless communication unit 120 to transmit the pico
system information in the macro cell 10.
[0105] Radio resource to be used in the downlink transmission of
the pico system information (which will be referred to hereinafter
as "resource for pico system information) is resource of a
frequency band used in the macro cell 10. In addition, the resource
for pico system information is resource that are not used in
transmission of system information of the frequency band used in
the macro cell 10 (which will be referred to hereinafter as "macro
system information"). In other words, the communication control
unit 153 causes the wireless communication unit 120 to transmit the
pico system information using different radio resource from radio
resource used in transmission of the macro system information.
[0106] In addition, for example, there are a plurality of pico
cells 20 in the macro cell 10. In this case, the resource for pico
system information are not used in transmission of system
information of a frequency band used in another pico cell 20 (in
other words, pico system information of another pico cell 20)
either. In other words, the communication control unit 153 causes
the wireless communication unit 120 to transmit pico system
information of each pico cell 20 using discrete radio resource.
[0107] In addition, as an example, the resource for pico system
information is resource of a physical downlink shared channel
(PDSCH).
[0108] Note that the communication control unit 153 also controls,
for example, downlink transmission of the macro system information
in the macro cell 10. The communication control unit 153 generates,
for example, macro system information. Then, the communication
control unit 153 causes the wireless communication unit 120 to
transmit the macro system information in the macro cell 10.
[0109] Notification of Radio Resource Used in Transmission of
System Information of a Pico Cell Side
[0110] In addition, the communication control unit 153 notifies the
UE 300 positioned within the macro cell 10 of the resource for pico
system information in the present embodiment. To be more specific,
for example, the communication control unit 153 causes the wireless
communication unit 120 to transmit information for specifying
resource for pico system information to the UE 300 positioned
within the macro cell 10. The information is, for example,
information representing a position of the resource for pico system
information in a frequency direction and a time direction (which
will be referred to hereinafter as "location of pico system
information (LPSI)"). LPSI includes, for example, a cycle, a
subframe number, a position of a resource block in a frequency
direction and a time direction, and the like.
[0111] In addition, the communication control unit 153 also
notifies the UE of, for example, a pico cell ID for identifying the
pico cell 20 along with the resource for pico system information.
To be specific, for example, the communication control unit 153
causes the wireless communication unit 120 to transmit a
combination of a pico cell ID and LPSI. Hereinbelow, a specific
example of this will be described with reference to FIGS. 7 and
8.
[0112] FIG. 7 is an illustrative diagram for describing an example
of information transmitted for notification of radio resource used
in transmission of system information of a pico cell side.
Referring to FIG. 7, three combinations of pico cell IDs and LPSI
are shown. When there are three pico cells 20 in the macro cell 10,
for example, a pico cell ID and LPSI are transmitted to the three
respective pico cells 20.
[0113] FIG. 8 is an illustrative diagram for describing an example
of correspondences between LPSI and radio resource. Referring to
FIG. 8, correspondences between the combinations of pico cell IDs
and LPSI shown in FIG. 7 and radio resource represented by the LPSI
are shown. In the radio resource represented by LPSI, system
information including MIBs and SIBs is transmitted. With the LPSI
with respect to each pico cell 20, the UE 300 can specify where
pico system information of each pico cell is.
[0114] In addition, the resource for pico system information are
notified of, for example, through signaling to the UE 300 that is
in a connected state in the macro cell 10. To be more specific, for
example, the communication control unit 153 causes the wireless
communication unit 120 to transmit the combinations of the pico
cell IDs and LPSI through RRC signaling to the UE 300 that is in
the RRC connection mode in the macro cell 10. The communication
control unit 153 may cause the wireless communication unit 120 to
transmit the respective combinations of the pico cell IDs and LPSI
separately from each other, or to transmit two or more of the
combinations as a whole.
3.2. Configuration of a Pico eNodeB
[0115] Next, an example of a configuration of the pico eNodeB 200
will be described with reference to FIG. 9. FIG. 9 is a block
diagram showing the example of the configuration of the pico eNodeB
200 according to the present embodiment. Referring to FIG. 9, the
pico eNodeB 200 is provided with an antenna unit 210, a wireless
communication unit 220, a network communication unit 230, a storage
unit 240, and a control unit 250.
(Antenna Unit 210)
[0116] The antenna unit 210 receives a radio signal and outputs the
received radio signal to the radio communication unit 220. The
antenna unit 210 transmits the transmitted signal output by the
radio communication unit 220.
(Wireless Communication Unit 220)
[0117] The wireless communication unit 220 wirelessly communicates
with the UE 300 that is positioned within the pico cell 20. As an
example, the wireless communication unit 220 wirelessly
communicates with the UE 300 using a frequency band of the 5 MHz
band. The wireless communication unit 120 includes, for example, an
RF circuit and other circuits.
(Network Communication Unit 230)
[0118] The network communication unit 230 communicates with other
devices. For example, the network communication unit 230
communicates with the macro eNodeB 100. The network communication
unit 230 includes, for example, a communication interface for any
type of wired communication.
(Storage Unit 240)
[0119] The storage unit 240 stores programs and data for operations
of the pico eNodeB 200. The storage unit 240 includes a storage
medium, for example, a hard disk, a semiconductor memory, or the
like.
(Control Unit 250)
[0120] The control unit 250 provides various functions of the pica
eNodeB 200. For example, the control unit 250 corresponds to a
processor such as a CPU or a DSP, and provides the various
functions by causing programs stored in the storage unit 240 or
other storage media to be executed. The control unit 250 includes a
communication control unit 251 and an information provision unit
253.
(Communication Control Unit 251)
[0121] The communication control unit 251 controls wireless
communication within the pico cell 20. Specifically, for example,
the communication control unit 251 generates system information of
a frequency band used in the pico cell 20 (in other words, pico
system information). The system information includes, for example,
an MIB and an SIB. The communication control unit 251 outputs the
generated pico system information to the information provision unit
253.
[0122] In addition, for example, the pico system information is not
transmitted in the pico cell 20. In other words, the communication
control unit 251 does not cause the wireless communication unit 220
to transmit pico system information in the pico cell 20.
(Information Provision Unit 253)
[0123] The information provision unit 253 provides the pico system
information to the macro eNodeB 100. To be specific, when the pico
system information is output by the communication control unit 251,
the information provision unit 253 acquires the pico system
information. Then, the information provision unit 253 causes the
network communication unit 230 to transmit the pico system
information to the macro eNodeB 100.
3.3. Configuration of a UE
[0124] Next, an example of a configuration of the UE 300 will be
described with reference to FIG. 10. FIG. 10 is a block diagram
showing the example of the configuration of the UE 300 according to
the present embodiment. Referring to FIG. 10, the UE 300 is
provided with an antenna unit 310, a wireless communication unit
320, a storage unit 330, and a control unit 340.
(Antenna Unit 310)
[0125] The antenna unit 310 receives a radio signal and outputs the
received radio signal to the radio communication unit 220. The
antenna unit 310 transmits a transmission signal output by the
radio communication unit 320.
(Wireless Communication Unit 320)
[0126] The wireless communication unit 320 wirelessly communicates
with the macro eNodeB 100 when it is positioned within the macro
cell 10. In addition, the wireless communication unit 320
wirelessly communicates with the pico eNodeB 200 when it is
positioned within the pico cell 20.
[0127] Particularly in the present embodiment, when the UE 300 is
positioned within the macro cell 10, the wireless communication
unit 320 receives system information of a frequency band used in
the pico cell 20 (i.e., pico system information). To be more
specific, for example, when the UE 300 is positioned within the
macro cell, the wireless communication unit 320 receives pico
system information transmitted by the macro eNodeB 100.
[0128] In addition, when, for example, the UE 300 is positioned
within the macro cell 10, the wireless communication unit 320
receives information for specifying resource for pico system
information. The information is, for example, LPSI. In addition,
the wireless communication unit 320 also receives a pico cell ID
along with the LPSI.
(Storage Unit 330)
[0129] The storage unit 330 stores programs and data for operations
of the UE 300. The storage unit 330 includes a storage medium, for
example, a hard disk, a semiconductor memory, or the like.
(Control Unit 340)
[0130] The control unit 340 provides various functions of the UE
300. For example, the control unit 340 corresponds to a processor
such as a CPU or a DSP, and provides the various functions by
causing programs stored in the storage unit 330 or other storage
media to be executed.
[0131] For example, the control unit 340 acquires control
information transmitted by the macro eNodeB 100 and the pico eNodeB
200. To be more specific, for example, the control unit 340
acquires the control information when the wireless communication
unit 320 receives the control information. As an example, a
position of radio resource in a frequency direction and a time
direction in which each piece of control information is transmitted
is known to the control unit 340. Therefore, the control unit 340
acquires information transmitted using the radio resource at the
known position as control information.
[0132] Particularly, in the present embodiment, when the UE 300 is
positioned within the macro cell 10 and radio resource used in
downlink transmission of pico system information are notified of,
the control unit 340 acquires information transmitted using the
radio resource as the pico system information.
[0133] To be more specific, for example, when the UE 300 is
positioned within the macro cell 10 and the wireless communication
unit 320 receives a pico cell ID and LPSI, the control unit 340
acquires the pico cell ID and the LPSI. Accordingly, the control
unit 340 can know radio resource that is used to transmit pico
system information of the pico cell 20. Then, when the information
transmitted using the radio resource is received by the wireless
communication unit 320, the control unit 340 acquires the
information as pico system information. In this way, the control
unit 340 acquires the pico system information of the pico cell
20.
[0134] Note that, since the UE 300 can know the pico cell ID from a
PSS and an SSS of the pico cell 20 in a cell search, the pico cell
20 found as a result of the cell search can be associated with the
system information acquired based on the LPSI using the pico cell
ID.
4. PROCESS FLOW
[0135] Next, an example of a communication control process
according to the present embodiment will be described with
reference to FIG. 11. FIG. 11 is a sequence diagram showing an
example of a schematic flow of the communication control process
according to the present embodiment.
[0136] In Step S401, the UE 300 is in the RRC connection mode with
the macro eNodeB 100.
[0137] In Step S403, the communication control unit 153 of the
macro eNodeB 100 causes the wireless communication unit 120 to
transmit a combination of a pico cell ID and LPSI. To be more
specific, the communication control unit 153 causes the wireless
communication unit 120 to transmit the combination of the pico cell
ID and the LPSI through RRC signaling to the UE 300 that is in the
RRC connection mode in the macro cell 10. Then, the wireless
communication unit 320 of the UE 300 receives the combination of
the pico cell ID and the LPSI, and the control unit 340 of the UE
300 acquires the combination of the pico cell ID and the LPSI.
[0138] In Step S405, the communication control unit 251 of the pico
eNodeB 200 generates system information of a frequency band used in
the pico cell 20 (i.e., pico system information). After that, in
Step S407, the information provision unit 253 of the pico eNodeB
200 causes the network communication unit 230 to transmit the pico
system information to the macro eNodeB 100. Then, the network
communication unit 130 of the macro eNodeB 100 receives the pico
system information and the information acquisition unit 151
acquires the pico system information.
[0139] In Step S409, the communication control unit 153 of the
macro eNodeB 100 causes the wireless communication unit 120 to
transmit the pico system information in the macro cell 10 using
radio resource represented by the LPSI. Then, the wireless
communication unit 320 of the UE 300 receives the pico system
information using the radio resource represented by the LPSI.
[0140] After that, in Step S411, the control unit 340 of the UE 300
acquires the information transmitted and received using the radio
resource represented by the LPSI as the pico system
information.
[0141] The configurations of the respective devices and the process
flow of the present embodiment have been described above. As
described above, the UE 300 is notified of radio resource of the
macro cell 10, then pico system information is transmitted in the
macro cell 10 using the radio resource, and accordingly, the UE 300
can acquire the pico system information in the macro cell 10. In
other words, an area in which the pico system information can be
acquired is not limited to the pico cell 20, but expands to the
macro cell 10. Thus, the UE 300 can acquire the pico system
information of the pico cell 20 before the UE comes close to the
pico cell 20. As a result, a time taken for connection of the UE
300 in the pico cell is shortened. For example, the UE 300
specifies the pico cell 20 in a cell search based on a PSS and an
SSS from limited pico cells 20 corresponding to pico system
information that has been acquired beforehand. For this reason, a
time taken to specify a cell is shortened. In addition, for
example, it is not necessary for the UE 300 to receive system
information again after the cell search. For this reason, a time
taken for connection in the pico cell 20 is shortened more.
[0142] Note that PDCCHs, each of which is a control channel in the
macro cell 10 and the pico cell 20, for example, are present in
both of the macro cell 10 and the pico cell 20 as in the related
art. Mainly on the PDCCHs, release assignment information (i.e.,
scheduling information) is transmitted. The scheduling information
includes downlink assignment (Downlink Assignment) and an uplink
grant (Uplink Grant). The downlink assignment indicates which
resource block (RB) among downlink RBs is the RB that a UE should
receive. On the other hand, the uplink grant indicates which RB
among uplink RBs is the RB that a UE should use in transmission.
The reason is that deciding this scheduling information in each of
eNodeBs (i.e., each macro eNodeB 100 and each pico eNodeB 200)
simplifies implementation of the wireless communication system.
When the pico eNodeB 200 is implemented as a remote radio head
(RRH), transmission of scheduling information of the pico eNodeB
side may also be possible on the PDCCH of the macro eNodeB side.
When the pico eNodeB 200 is not implemented as an RRH, however, the
presence of the PDCCHs in each cell (i.e., each macro cell and each
pico cell) is considered to be natural.
[0143] In addition, in order to secure synchronization in a pico
cell, transmission of synchronization signals of PSSs and SSSs by
the pico eNodeB 200 is also considered to be natural.
[0144] On the other hand, taking the small area of the pico cell
20, transmission of system information of the pico cell 20, system
information updating, paging channels, and the like in the macro
cell 10 rather than the pico cell 20 is considered to be natural.
In addition, signaling to the UE via the macro eNodeB 100 is
considered to be desirable. This is because the pico eNodeB 200
should concentrate on transmission and reception of user data.
5. MODIFIED EXAMPLES
[0145] Next, a first modified example and a second modified example
according to the present embodiment will be described with
reference to FIGS. 12 to 19.
5.1. First Modified Example
[0146] First, the first modified example according to the present
embodiment will be described with reference to FIGS. 12 to 16.
<5.1.1. Overview>
[0147] In the examples of the present embodiment described above,
radio resource that is used in transmission of pico system
information (i.e., resource for pico system information) are
notified of through signaling (for example, RRC signaling) to the
UE 300 that is in a connection state in the macro cell 10. In this
case, the UE 300 that is not in a connection state in the macro
cell 10 (i.e., the UE 300 in an idle state) does not receive a
notification through signaling, and thus fails to acquire pico
system information. For this reason, it is not possible to cause
the above-described examples to correspond to a case in which, for
example, the UE 300 intends to perform wireless communication in a
specific pico cell 20 and then is in a connection state in the
macro cell 10.
[0148] Thus, in the first modified example of the present
embodiment, resource for pico system information are notified of
using radio resource for notification that have a predetermined
positional relation with other radio resource that is used in
transmission of a predetermined information block included in macro
system information. To be specific, for example, LPSI is
transmitted using radio resource for notification that have a
predetermined positional relation with other radio resource that is
used in transmission of a predetermined information block included
in macro system information.
[0149] Even a UE 300 that is not in a connection state in the macro
cell 10 can acquire system information of the macro cell 10. Thus,
according to the first modified example, when the UE 300 that is
not in a connection state in the macro cell 10 acquires the
predetermined information block, information transmitted with radio
resource that has a predetermined positional relation with radio
resource for transmission of the information block can be acquired
as information that represents resource for the pico system
information (i.e., LPSI). Then the UE 300 can acquire information
transmitted with the resource for pico system information
represented by the information as pico system information. In other
words, the UE 300 can acquire pico system information even when it
is not in a connection state in the macro cell 10.
<5.1.2. Configurations of Respective Devices
[0150] Next, configurations of respective devices according to the
first modified example of the present embodiment will be described
with reference to FIGS. 12 to 15. Herein, only changes from the
content that has already been described with reference to FIGS. 6,
9, and 10 will be described.
(Macro eNodeB 100)
[0151] Communication Control Unit 153
[0152] As described above, resource for pico system information are
notified of using radio resource for notification that have a
predetermined positional relation with other radio resource that is
used in transmission of a predetermined information block included
in macro system information. To be specific, the communication
control unit 153 causes the wireless communication unit 120 to
transmit a pico cell ID and LPSI using radio resource for
notification that have a predetermined positional relation with
other radio resource that is used in transmission of a
predetermined information block included in macro system
information.
[0153] The other radio resource used in transmission of the
predetermined information block included in the macro system
information is, for example, resource positioned within a
predetermined range of a time direction and a frequency direction.
As an example, the predetermined information block is the SIB 1
among system information blocks (SIBs). In addition, the other
radio resource is resource used in transmission of the SIB 1. In
other words, the communication control unit 153 causes the wireless
communication unit 120 to transmit the pico cell ID and LPSI using
radio resource that has a predetermined positional relation with
the radio resource used in transmission of the SIB 1. Hereinbelow,
the position of the radio resource used in transmission of the SIB
1 will be described with reference to FIG. 12.
[0154] FIG. 12 is an illustrative diagram for describing an example
of a position of radio resource used in transmission of the SIB 1.
Referring to FIG. 12, two consecutive radio frames, i.e., a radio
frame whose SFN is an even number and a radio frame whose SFN is an
odd number, are shown. In addition, the SIB 1 is transmitted in a
#5 subframe of the radio frame whose SFN is an even number. To be
more specific, the SIB 1 is transmitted on a PDSCH in the #5
subframe. To be more specific, the position of the SIB 1 is fixed
in the time direction in the #5 subframe, but variable in the
frequency direction. The position of the SIB 1 in the frequency
direction is notified of using an MIB 1. In the first modified
example of the present embodiment, LPSI is transmitted with radio
resource that has a predetermined positional relation with
semi-fixed radio resource used in transmission of the SIB 1.
[0155] In addition, the predetermined positional relation is a
positional relation that has a predetermined offset with the other
radio resource in the time direction and the frequency direction.
As an example, the predetermined positional relation is a
positional relation that has a predetermined offset with the radio
resource used in the transmission of the SIB 1 in the time
direction and the frequency direction. In other words, the
communication control unit 153 causes the wireless communication
unit 120 to transmit the pico cell ID and the LPSI using radio
resource that has a predetermined offset with the radio resource
used in the transmission of the SIB 1 in the time direction and the
frequency direction. Hereinbelow, a specific example of radio
resource that has a predetermined offset will be described with
reference to FIGS. 13 to 15.
[0156] FIG. 13 is an illustrative diagram for describing a first
example of radio resource used in transmission of LPSI according to
the first modified example of the present embodiment. Referring to
FIG. 13, radio resource of the macro cell 10 in the #5 subframe of
the radio frame whose SFN is an even number are shown. As shown in
FIG. 13, for example, the radio resource used in transmission of
LPSI have a predetermined offset with radio resource used in
transmission of the SIB 1 in the frequency direction.
[0157] FIG. 14 is an illustrative diagram for describing a second
example of the radio resource used in transmission of LPSI
according to the first modified example of the present embodiment.
Referring to FIG. 14, radio resource of the macro cell 10 in the #5
subframe of the radio frame whose SFN is an even number are shown.
As shown in FIG. 14, for example, the radio resource used in
transmission of the LPSI has a predetermined offset with the radio
resource used in transmission of the SIB 1 in the time direction.
To be more specific, the radio resource used in transmission of the
LPSI are transmitted in the #5 subframe, and transmitted using an
OFDM symbol different from that of the radio resource used in
transmission of the SIB 1.
[0158] FIG. 15 is an illustrative diagram for describing a third
example of the radio resource used in transmission of LPSI
according to the first modified example of the present embodiment.
Referring to FIG. 15, two consecutive radio frames, i.e., a radio
frame whose SFN is an even number and a radio frame whose SFN is an
odd number, are shown. In addition, the SIB 1 is transmitted in the
#5 subframe whose SFN is an even number. On the other hand, the
LPSI is transmitted in the #5 subframe whose SFN is an odd number.
The radio resource used in transmission of the LPSI have an offset
of one radio frame with respect to the radio resource used in
transmission of the SIB 1 in the time direction.
[0159] Note that the radio resource used in transmission of the
LPSI have predetermined offsets with the radio resource used in
transmission of the SIB 1 in the frequency direction and the time
direction as above. Note that the predetermined offset is not
limited to the above-described example, and various offsets can be
applied. In addition, the predetermined offset is not limited to
one offset of those in the frequency direction and the time
direction, and predetermined offsets in both of the frequency
direction and the time direction can be applied.
[0160] Note that, for example, the pico cell ID also is transmitted
using radio resource that has the predetermined offset along with
the LSPI.
(UE 300)
[0161] Control Unit 340
[0162] If radio resource used in downlink transmission of pico
system information (i.e., resource for pico system information) are
notified of when the UE 300 is positioned within the macro cell 10,
the control unit 340 acquires information transmitted using the
radio resource as the pico system information. Particularly in the
first modified example of the present embodiment, the resource for
pico system information is notified of using radio resource for
notification that have a predetermined positional relation with
other radio resource that is used in transmission of a
predetermined information bock included in macro system
information. In other words, the control unit 340 receives a
notification of the resource for pico system information using the
radio resource for notification. To be specific, for example, a
pico cell ID and LSPI transmitted using radio resource that have a
predetermined positional relation with the radio resource used in
transmission of the SIB 1 are received by the wireless
communication unit 320. Then, the control unit 340 acquires
information transmitted using the radio resource that has the
predetermined positional relation as the pico cell ID and the LSPI.
Note that details of the predetermined positional relation are as
described above.
<5.1.3. Process Flow>
[0163] Next, an example of a communication control process
according to the first modified example of the present embodiment
will be described with reference to FIG. 16. FIG. 16 is a sequence
diagram showing an example of a schematic flow of the communication
control process according to the first modified example of the
present embodiment.
[0164] In Step S501, the communication control unit 153 of the
macro eNodeB 100 generates macro system information.
[0165] Then, in Step S503, the communication control unit 153 of
the macro eNodeB 100 causes the wireless communication unit 120 to
transmit the macro system information in the macro cell 10. In
addition, the communication control unit 153 causes the wireless
communication unit 120 to transmit the pico cell ID and the LPSI
using radio resource that has a predetermined offset with radio
resource that is used in transmission of the SIB 1 of the macro
system information. On the other hand, the wireless communication
unit 320 of the UE 300 receives the macro system information, and
receives the pico cell ID and the LPSI using the radio resource
that has the predetermined offset.
[0166] In Step S505, the control unit 340 of the UE 300 acquires
the macro system information. In addition, in Step S507, the
control unit 340 acquires the pico cell ID and the LPSI. To be
specific, for example, the control unit 340 acquires information
transmitted using the radio resource that has the predetermined
offset with the radio resource used in transmission of the SIB 1 as
the pico cell ID and the LPSI.
[0167] In Step S509, the communication control unit 251 of the pico
eNodeB 200 generates pico system information. Then, in Step S511,
the information provision unit 253 of the pico eNodeB 200 causes
the network communication unit 230 to transmit the pico system
information to the macro eNodeB 100. Then, the network
communication unit 130 of the macro eNodeB 100 receives the pico
system information, and the information acquisition unit 151
thereof acquires the pico system information.
[0168] In Step S513, the communication control unit 153 of the
macro eNodeB 100 causes the wireless communication unit 120 to
transmit the pico system information in the macro cell 10 using
radio resource represented by the LPSI. Then, the wireless
communication unit 320 of the UE 300 receives the pico system
information using the radio resource represented by the LPSI.
[0169] Then, in Step S515, the control unit 340 of the UE 300
acquires the information transmitted and received using the radio
resource represented by the LPSI as the pico system
information.
5.2. Second Modified Example
[0170] Next, the second modified example according to the present
embodiment will be described with reference to FIGS. 17 to 19.
<5.2.1. Overview>
[0171] As described above, pico system information is transmitted
by the macro eNodeB 100 in the embodiment and the first modified
example of the embodiment. For this reason, updating of system
information is also basically transmitted by the macro eNodeB 100.
In such a case, if updating of both of macro system information and
pico system information is notified of as notification of system
information updating, the frequency of system information updating
becomes very high. For example, if there are 20 pico cells 20
within the macro cell 10, updating of system information is
frequently performed. Then, a process on the UE 300 side occurs
each time system information is updated. As a result, the UE 300
increasingly consumes power.
[0172] Thus, in the second modified example of the embodiment,
updating of system information of a frequency band used in the pico
cell 20 (i.e., pico system information) is notified of
independently of updating of system information of the frequency
band used in the macro cell 10 (i.e., macro system information).
For example, updating of pico system information is notified of
along with resource for pico system information. To be more
specific, for example, information representing updating of pico
system information is transmitted along with LPSI.
[0173] When updating of macro system information together with pico
system information is set to be notified of, if one of the macro
system information and pico system information is updated, it is
notified of as updating of system information. Thus, the UE 300
that wirelessly communicates only in the macro cell 10 checks
updating of system information even when only pico system
information has been updated. As a result, a load of the UE 300
increases. Thus, by setting updating of macro system information to
be notified of separately from updating of pico system information
as described above, the UE 300 that wirelessly communicates only in
the macro cell 10 can check updating of system information only
when the macro system information has been updated. As a result,
the frequency of the UE 300 that wirelessly communicates only in
the macro cell 10 checking updating of system information can be
suppressed.
<5.2.2. Configurations of Respective Devices>
[0174] Next, configurations of the respective devices according to
the second modified example of the embodiment will be described
with reference to FIGS. 17 and 18. Herein, only changes from the
first modified example of the embodiment will be described.
(Macro eNodeB 100)
[0175] Communication Control Unit 153
[0176] The communication control unit 153 performs notification of
updating of system information. For example, the communication
control unit 153 performs notification of macro system information.
To be more specific, the communication control unit 153 performs
notification of updating of macro system information using a paging
channel. In addition, the communication control unit 153 performs
notification of updating of macro system information using the SIB
1 of the macro system information.
[0177] Particularly, in the second modified example of the
embodiment, the communication control unit 153 performs updating of
pico system information independently of updating of macro system
information. To be more specific, for example, the communication
control unit 153 does not perform notification of updating of pico
system information using the paging channel and the SIB 1.
[0178] In addition, updating of system information of a frequency
band used in the pico cell 20 (i.e., pico system information), for
example, is notified of independently of updating of system
information of a frequency band used in another pico cell 20 (i.e.,
pico system information of another cell 20). In other words, the
communication control unit 153 separately performs notification of
updating of pico system information for each pico cell 20.
[0179] In addition, for example, updating of pico system
information is notified of along with radio resource used in the
downlink transmission of the pico system information (i.e.,
resource for the pico system information). In other words, the
communication control unit 153 performs notification of updating of
pico system information along with resource for the pico system
information. To be more specific, for example, the communication
control unit 153 transmits information indicating whether or not
pico system information has been updated (which will be referred to
hereinafter as "pico system information updating information") to
the wireless communication unit 120 along with a cell ID and LPSI.
Hereinbelow, this will be described in detail with reference to
FIGS. 17 and 18.
[0180] FIG. 17 is an illustrative diagram for describing an example
of information transmitted for notification of updating of system
information of a pico cell side. Referring to FIG. 17, three
combinations each having a pico cell ID, LPSI, and pico system
information updating information (UPDATE INFO) are shown. When, for
example, there are three pico cells 20 in the macro cell 10, pico
cell IDs, LPSI, and pico system information updating information of
the three respective pico cells 20 are transmitted.
[0181] FIG. 18 is an illustrative diagram for describing an example
of correspondences between pico system information and information
transmitted to notify of updating of the pico system information.
Referring to FIG. 18, the correspondences between the combinations
of the pico cell IDs, LPSI, and pico system information updating
information shown in FIG. 17 and radio resource represented by the
LPSI are shown. In the radio resource represented by the LPSI,
system information including MIBs and SIBS is transmitted. With the
pico system information updating information of each of the pico
cells 20, the UE 300 can know whether or not individual pico system
information of each pico cell 20 has been updated.
[0182] Note that, as described as the first modified example of the
present embodiment, for example, resource for pico system
information are notified of using radio resource for notification
that have a predetermined positional relation with other radio
resource that is used in transmission of a predetermined
information block included in macro system information. Thus,
updating of the pico system information is also notified of using
the radio resource for notification that have a predetermined
positional relation with the other radio resource that is used in
transmission of the predetermined information block. To be
specific, for example, the communication control unit 153 causes
the wireless communication unit 120 to transmit the pico cell IDs,
LPSI, and pico system information updating information using the
radio resource for notification that have the predetermined
positional relation with the other radio resource that is used in
transmission of the predetermined information block.
[0183] As an example, the predetermined information block is, for
example, the SIB 1 of the macro system information. In addition,
the predetermined positional relation is a positional relation that
has a predetermined offset with the other radio resource used in
transmission of the predetermined information block in the time
direction or the frequency direction. In other words, the
communication control unit 153 causes the wireless communication
unit 120 to transmit the pico cell IDs, LPSI, and pico system
information updating information using the radio resource that have
the predetermined offset with the radio resource that is used in
transmission of the SIB 1 of the macro system information.
(UE 300)
[0184] Control Unit 340
[0185] The control unit 340 is notified of updating of system
information by the macro eNodeB. For example, the control unit 340
is notified of updating of macro system information. To be more
specific, for example, the control unit 340 is notified of updating
of macro system information using a paging channel and the SIB 1 of
the macro system information.
[0186] Particularly in the second modified example of the present
embodiment, the control unit 340 is notified of updating of pico
system information independently of updating of the macro system
information. To be more specific, for example, the control unit 340
is not notified of updating of pico system information using the
paging channel and the SIB 1. In addition, for example, the control
unit 340 is separately notified of updating of pico system
information for each pico cell 20.
[0187] In addition, for example, the control unit 340 is notified
of updating of pico system information along with resource for pico
system information. To be more specific, for example, when pico
system information updating information is received by the wireless
communication unit 320 along with a cell ID and LPSI, the control
unit 340 acquires the pico system information updating information
along with the cell ID and the LPSI.
[0188] To be more specific, for example, the cell ID, the LPSI, and
the pico system information updating information are transmitted
using, for example, radio resource that have a predetermined
positional relation with the radio resource used in transmission of
the SIB 1, and then received by the wireless communication unit
320. Then, the control unit 340 acquires the information
transmitted using the radio resource that has the predetermined
positional relation as the pico cell ID, the LSPI, and the pico
system information updating information.
<5.2.3. Process Flow>
[0189] Next, an example of a communication control process
according to the second modified example of the embodiment will be
described with reference to FIG. 19. FIG. 19 is a sequence diagram
showing an example of a schematic flow of the communication control
process according to the second modified example of the embodiment.
Here, only Steps S521, S523, S525, and S527 which are differences
between the example of the schematic flow of the communication
control process according to the first modified example shown in
FIG. 16 and the example of the schematic flow of the communication
control process according to the second modified example shown in
FIG. 19 will be described.
[0190] In Step S521, the communication control unit 153 of the
macro eNodeB 100 causes the wireless communication unit 120 to
transmit macro system information in the macro cell 10. In
addition, the communication control unit 153 causes the wireless
communication unit 120 to transmit a pico cell ID, LPSI, and pico
system information updating information using radio resource that
has a predetermined offset with radio resource that is used in
transmission of the SIB 1 of the macro system information. On the
other hand, the wireless communication unit 320 of the UE 300
receives the macro system information, and receives the pico cell
ID, the LPSI, and the pico system information updating information
using the radio resource that has the predetermined offset.
[0191] In Step S523, the control unit 340 of the UE 300 acquires
the pico cell ID, the LPSI, and the pico system information
updating information. To be specific, for example, the control unit
340 acquires information transmitted using the radio resource that
has the predetermined offset with the radio resource used in
transmission of the SIB 1 as the pico cell ID, the LPSI, and the
pico system information updating information.
[0192] In Step S525, the control unit 340 of the UE 300 checks
whether or not the pico system information has been updated from
the pico system information updating information.
[0193] In Step S527, the control unit 340 of the UE 300 checks the
updated spot of the pico system information when the pico system
information has been updated.
6. CONCLUSION
[0194] Hereinabove, the communication devices and processes
according to embodiments of the present disclosure have been
described using FIGS. 1 to 19. According to the embodiments
relating to the present disclosure, system information of a
frequency band that is used in the pico cell 20 (i.e., pico system
information) is acquired, and downlink transmission of the pico
system information in the macro cell 10 is controlled. In addition,
the UE 300 that is positioned within the macro cell 10 is notified
of radio resource that is used in the downlink transmission of the
pico system information (i.e., resource for the pico system
information).
[0195] By notifying the UE 300 of the radio resource in the macro
cell 10 and transmitting the pico system information in the macro
cell 10 using the radio resource as described above, the UE 300 can
acquire the pico system information in the macro cell 10. In other
words, an area in which the pico system information can be acquired
is not limited to the pico cell 20, and expands to the macro cell
10. Thus, the UE 300 acquires the pico system information of the
pico cell 20 before it comes close to the pico cell 20. As a
result, a time taken for connection of the UE 300 in the pico cell
becomes short. For example, the UE 300 specifies a pico cell 20
based on a PSS and an SSS from limited pico cells 20 which
correspond to pico system information acquired in advance in a cell
search. For this reason, a time necessary for specifying a cell is
shortened. In addition, for example, it is not necessary for the UE
300 to receive system information again after the cell search. For
this reason, a time taken for connection in the pico cell 20 is
shortened more.
[0196] In addition, for example, the radio resource that is used in
the downlink transmission of the pico system information (i.e., the
resource for the pico system information) is resource of a
frequency band that is used in the macro cell 10. In addition, the
resource for the pico system information is resource that is not
used in transmission of the system information of the frequency
band that is used in the macro cell 10.
[0197] Radio resource that is used in transmission of macro system
information (particularly, radio resource that is used in
transmission of the MIB and SIB 1) have no spare bits with which
other information is transmitted. Thus, when pico system
information is also transmitted with the radio resource, there can
be cases in which the radio resource is insufficient. That is to
say, the radio resource should be expanded. Thus, if macro system
information and pico system information are transmitted separately
from each other as described above, there will not be such a case
in which radio resource that is used in transmission of the macro
system information are insufficient. Moreover, there is no need to
expand the radio resource.
[0198] In addition, when macro system information and pico system
information are transmitted separately from each other and only one
of the macro system information and the pico system information is
desired to be acquired, only the one can be selectively acquired.
Thus, it is good for the UE 300 to acquire only necessary system
information, and accordingly, a load of the UE 300 can be
suppressed.
[0199] In addition, if pico system information is included as a
part of macro system information, the frequency of updating the
macro system information becomes high. In other words, when pico
system information of any pico cell 20 is updated, the macro system
information is updated. As a result, the UE 300 which wirelessly
communicates only in the macro cell 10 checks updating of the
system information more often than necessary, and a load of the UE
300 increases accordingly. Therefore, by transmitting the macro
system information and the pico system information separately from
each other as described above, the frequency of updating the macro
system information can be suppressed. As a result, the frequency of
the UE 300 that wirelessly communicates only in the macro cell 10
checking updating of system information can be suppressed.
[0200] In addition, for example, the resource for the pico system
information are not used in transmission of system information of a
frequency band that is used in another pico cell 20 (i.e., pico
system information of another pico cell 20) either.
[0201] Accordingly, necessary pico system information can be
selectively acquired from pico system information of a plurality of
pico cells 20. Thus, it is good for the UE 300 to acquire only
necessary pico system information, and accordingly, a load of the
UE 300 can be suppressed.
[0202] In addition, when pico system information of a plurality of
pico cells 20 is collectively transmitted, if pico system
information of any pico cell 20 is updated, the updating of the
pico system information is notified of. As a result, the UE 300
checks updating of pico system information each time pico system
information of any pico cell 20 is updated regardless of whether
pico system information of the pico cell 20 that relates to the
device itself is updated. Accordingly, a load of the UE 300
increases. Therefore, by individually transmitting pico system
information of each pico cell 20, a frequency of the UE 300
checking updating of pico system information can be suppressed.
[0203] In addition, for example, the resource for the pico system
information is resource of a physical downlink shared channel.
[0204] Accordingly, the necessary amount of resource of pico system
information can be secured, and thus even if the number of pico
cells 20 increases, pico system information can be transmitted in
the macro cell 10. In addition, if pico system information is
transmitted on a physical downlink shared channel, a UE that need
not acquire pico system information is not affected thereby at all,
and therefore it gives no load to the UE.
[0205] In addition, for example, the resource for the pico system
information is notified of through signaling to the UE 300 that is
in a connection state in the macro cell 10.
[0206] Accordingly, the resource for the pico system information
can be specified without a special operation of the UE 300 being
performed.
[0207] In addition, for example, a pico cell ID for identifying the
pico cell 20 is also notified of, along with the resource for the
pico system information.
[0208] Accordingly, the UE 300 can know corresponding pico system
information of pico cells 20 for all resource for the pico system
information that are notified of. Thus, the UE 300 can easily
acquire pico system information of a desired pico cell 20.
[0209] In addition, for example, pico system information of a
frequency band used in a pico cell 20 is not transmitted in the
pico cell.
[0210] Accordingly, more radio resource can be used in transmission
of user data in the pico cell 20.
[0211] In addition, according to the first modified example of the
embodiment relating to the present disclosure, resource for pico
system information are notified of using radio resource for
notification that has a predetermined positional relation with
other radio resource that is used in transmission of a
predetermined information block included in macro system
information.
[0212] Even a UE 300 that is not in a connection state in the macro
cell 10 can acquire system information of the macro cell 10. Thus,
according to the first modified example, when acquiring the
predetermined information block, the UE 300 that is not in a
connection state in the macro cell 10 can acquire information
transmitted with radio resource that has the predetermined
positional relation with the radio resource for transmission of the
information block as information representing the resource for pico
system information (i.e., LPSI). Then, the UE 300 can acquire
information transmitted with the resource for the pico system
information represented by the information as pico system
information. In other words, the UE 300 can acquire pico system
information even when the UE is not in a connection state in the
macro cell 10.
[0213] In addition, for example, the other radio resource that is
used in the transmission of the predetermined information block
included in the macro system information is resource positioned
within a predetermined range in a time direction and a frequency
direction.
[0214] When the position of the radio resource used in transmission
of the information block (for example, the SIB 1) significantly
changes, the radio resource that has the predetermined positional
relation (for example, the radio resource used in transmission of
the LPSI) are not necessarily radio resource that can be freely
used. For example, there is also a possibility of the radio
resource that has the predetermined positional relation being radio
resource to be used in transmission of another information block or
other important control information. Thus, if the radio resource
used in transmission of the information block is resource for
transmission at a semi-fixed position as described above, the
predetermined positional relation can be set so that the radio
resource that has the predetermined positional relation is freely
usable resource.
[0215] In addition, for example, the predetermined positional
relation is a positional relation that has a predetermined offset
with the other radio resource in the time direction or the
frequency direction.
[0216] Accordingly, the UE 300 can easily specify the position of
the radio resource that has the predetermined positional relation
(for example, the radio resource used in transmission of the LPSI)
from the position of the radio resource used in transmission of the
information block (for example the SIB 1).
[0217] In addition, according to a third modified example of the
embodiment relating to the present disclosure, updating of system
information of a frequency band used in a pico cell 20 (i.e., pico
system information) is notified of independently of updating of
system information of the frequency band used in a macro cell 10
(i.e., macro system information).
[0218] When updating of macro system information and pico system
information are collectively notified of, if one of the macro
system information and the pico system information is updated, it
is notified of as updating of system information. Thus, the UE 300
that wirelessly communicates only in the macro cell 10 checks the
updating of system information even when only the pico system
information is updated. As a result, a load of the UE 300
increases. Thus, by notifying of updating of the macro system
information and updating of the pico system information separately
from each other as described above, the UE 300 that wirelessly
communicates only in the macro cell 10 can check updating of system
information only when the macro system information has been
updated. As a result, the frequency of the UE 300 that wirelessly
communicates only in the macro cell 10 checking updating of system
information can be suppressed.
[0219] In addition, for example, updating of system information of
a frequency band used in a pico cell 20 (i.e., pico system
information) is notified of independently of updating of system
information of a frequency band used in another pico cell 20 (i.e.,
pico system information of another cell 20).
[0220] When updating of pico system information of a plurality of
pico cells 20 is collectively notified of, if pico system
information of any pico cell 20 among the plurality of pico cells
20 is updated, it is notified of as updating of system information.
Thus, the UE 300 checks updating of pico system information even
when pico system information of a pico cell 20 that is irrelevant
to the device itself has been updated. As a result, a load of the
UE 300 increases. Thus, as updating of pico system information of
each pico cell 20 is individually notified of, the UE 300 can check
updating of system information only when pico system information of
a pico cell 20 that relates to the device itself has been updated.
As a result, the frequency of the UE 300 checking updating of
system information can be suppressed.
[0221] In addition, for example, updating of pico system
information is notified of along with radio resource used in the
downlink transmission of the pico system information (i.e.,
resource for the pico system information).
[0222] Accordingly, it is possible to check whether or not the pico
system information has been updated like the pico system
information resource.
[0223] The preferred embodiments of the present disclosure have
been described above with reference to the accompanying drawings,
whilst the present disclosure is not limited to the above examples,
of course. A person skilled in the art may find various alterations
and modifications within the scope of the appended claims, and it
should be understood that they will naturally come under the
technical scope of the present disclosure.
[0224] Although, for example, the example in which the LPSI and the
pico system information updating information are transmitted using
radio resource that has a predetermined offset with radio resource
used in transmission of the SIB 1 has been described in the second
modified example as in the first modified example, the present
disclosure is not limited thereto. For example, the LPSI and the
pico system information updating information may be transmitted
through RRC signaling.
[0225] In addition, although the example in which one frequency
band is used in each of a macro cell and a pico cell has been
described as an example, the present disclosure is not limited
thereto. A plurality of frequency bands may be used in one or both
of the macro cell and pico cell. As an example, a carrier
application may be applied to a pico cell. In addition, system
information of each CC used in a pico cell may be transmitted using
a frequency band used in a macro cell. In addition, pico system
information of each of CCs may be collectively transmitted in units
of pico cells. In such a case, LPSI may represent the position of
radio resource used to collectively transmit the pico system
information in units of pico cells. Alternatively, pico system
information of each of CCs may be individually transmitted in units
of CCs. In this case, the LPSI may represent the position of the
radio resource used to individually transmit the pico system
information in units of CCs. Note that, as another example, a
carrier application may be applied to a macro cell. In addition,
system information of a frequency band used in a pico cell may be
transmitted using any CC used in a macro cell.
[0226] In addition, although the example in which a CC used in a
macro cell is a frequency band of the 2 MHz band and a frequency
band used in a pico cell is a frequency band of the 5 GHz band has
been described as an example, the present disclosure is not limited
thereto. For example, a frequency band of the same band (for
example, the 2 GHz band) may be used in both of a macro cell and a
pico cell. In addition, a frequency band used in a macro cell and a
frequency band used in a pico cell may be different frequency
bands, or the same frequency band.
[0227] In addition, although the example in which the macro eNodeB
and the pico eNodeB perform wired communication has been described,
the present disclosure is not limited thereto. Instead of wired
communication, wireless communication (for example, microwave
communication) may be performed.
[0228] In addition, although the example in which the pico eNodeB
is a normal eNodeB has been described, the present disclosure is
not limited thereto. The pico eNodeB may be implemented as an RRH.
In such a case, for example, a control unit of the pico eNodeB may
be provided in a macro eNodeB or another communication control
device.
[0229] In addition, the macro eNodeB may be configured by a
plurality of devices rather than one device. For example, the macro
eNodeB may include a communication control device that includes at
least a control unit as one of the plurality of devices.
[0230] In addition, although the example of the wireless
communication system based on LTE has been described, the present
disclosure is not limited thereto. The technology relating to the
present disclosure can also be applied to a wireless communication
system of another communication standard in which transmission of
system information is performed. Also, although description has
been provided using the eNodeB as an example of a base station and
the UE as an example of a terminal device, the present disclosure
is not limited thereto. The technology relating to the present
disclosure can also be applied to a base station and a terminal
device that are based on another communication standard.
[0231] In addition, although the example in which a small cell that
is partially or entirely overlapped by a macro cell is a pico cell
has been described, the present disclosure is not limited thereto.
The small cell may be, for example, a femto cell, a nano cell, or a
micro cell.
[0232] Also, the processing steps in a communication control
process in this specification are not strictly limited to being
executed in a time series following the sequence described in a
flowchart. For example, the processing steps in a communication
control process may be executed in a sequence that differs from a
sequence described herein as a flowchart, and furthermore may be
executed in parallel.
[0233] In addition, it is possible to create a computer program for
causing hardware such as a CPU, ROM, and RAM built into a
communication control device or a terminal device to exhibit
functions similar to each structural element of the foregoing
communication control device or terminal device.
[0234] Additionally, the present technology may also be configured
as below.
(1)
[0235] A communication control device including:
[0236] an acquisition unit configured to acquire system information
of a frequency band that is used in a small cell that is partially
or entirely overlapped by a macro cell; and
[0237] a control unit configured to control downlink transmission
of the system information in the macro cell,
[0238] wherein the control unit notifies a terminal device
positioned within the macro cell of radio resource that is used in
the downlink transmission.
(2)
[0239] The communication control device according to (1), wherein
the radio resource is resource of a frequency band that is used in
the macro cell and the resource that is not used in transmission of
the system information of the frequency band.
(3)
[0240] The communication control device according to (2), wherein
the radio resource is not used in transmission of system
information of a frequency band that is used in another small cell
either.
(4)
[0241] The communication control device according to (2) or (3),
wherein the radio resource is resource of a physical downlink
shared channel.
(5)
[0242] The communication control device according to any one of (2)
to (4), wherein updating of the system information of the frequency
band that is used in the small cell is notified of independently of
updating of the system information of the frequency band that is
used in the macro cell.
(6)
[0243] The communication control device according to (5), wherein
updating of the system information of the frequency band that is
used in the small cell is also notified of independently of
updating of system information of a frequency band that is used in
another small cell.
(7)
[0244] The communication control device according to (5) or (6),
wherein, for the updating of the system information of the
frequency band that is used in the small cell, information
pertaining to the updating is notified of along with the radio
resource.
(8)
[0245] The communication control device according to any one of (2)
to (7), wherein the radio resource is notified of using radio
resource for notification that has a predetermined positional
relation with another radio resource that is used in transmission
of a predetermined information block included in the system
information of the frequency band used in the macro cell.
(9)
[0246] The communication control device according to (8), wherein
the another radio resource is resource positioned within a
predetermined range in a time direction and a frequency
direction.
(10)
[0247] The communication control device according to (8) or (9),
wherein the predetermined positional relation is a positional
relation that has a predetermined offset with the another radio
resource in a time direction or a frequency direction.
(11)
[0248] The communication control device according to any one of (2)
to (7), wherein the radio resource is notified of through signaling
to a terminal device that is in a connection state in the macro
cell.
(12)
[0249] The communication control device according to any one of (2)
to (11), wherein the control unit also notifies small cell
identification information for identifying the small cell along
with the radio resource.
(13)
[0250] The communication control device according to any one of (1)
to (12), wherein the system information of the frequency band that
is used in the small cell is not transmitted in the small cell.
(14)
[0251] A program causing a computer to function as:
[0252] an acquisition unit configured to acquire system information
of a frequency band that is used in a small cell that is partially
or entirely overlapped by a macro cell; and
[0253] a control unit configured to control downlink transmission
of the system information in the macro cell,
[0254] wherein the control unit notifies a terminal device
positioned within the macro cell of radio resource that is used in
the downlink transmission.
(15)
[0255] A communication control method including:
[0256] acquiring system information of a frequency band that is
used in a small cell that is partially or entirely overlapped by a
macro cell;
[0257] controlling downlink transmission of the system information
in the macro cell; and
[0258] notifying a terminal device positioned within the macro cell
of radio resource that is used in the downlink transmission.
(16)
[0259] A communication control device including:
[0260] a generation unit configured to generate system information
of a frequency band that is used in a small cell that is partially
ore entirely overlapped by a macro cell; and
[0261] a provision unit configured to provide the system
information to the device that is a device controlling downlink
transmission of the system information in the macro cell and
notifying a terminal device positioned within the macro cell of
radio resource that is used in the downlink transmission.
(17)
[0262] A program causing a computer to function as:
[0263] a generation unit configured to generate system information
of a frequency band that is used in a small cell that is partially
or entirely overlapped by a macro cell; and
[0264] a provision unit configured to provide the system
information to a device that is a device controlling downlink
transmission of the system information in the macro cell and
notifying a terminal device positioned within the macro cell of
radio resource that is used in the downlink transmission.
(18)
[0265] A communication control method including:
[0266] generating system information of a frequency band that is
used in a small cell that is partially or entirely overlapped by a
macro cell; and
[0267] providing the system information to a device that is a
device controlling downlink transmission of the system information
in the macro cell and notifying a terminal device positioned within
the macro cell of radio resource that is used in the downlink
transmission.
(19)
[0268] A terminal device including:
[0269] a wireless communication unit configured to receive system
information of a frequency band that is used in a small cell that
is partially or entirely overlapped by a macro cell when the
terminal device is positioned within the macro cell; and
[0270] an acquisition unit configured to acquire information
transmitted using radio resource as the system information when the
terminal device is positioned within the macro cell and the radio
resource that is used in downlink transmission of the system
information is notified of.
(20)
[0271] A communication control method including:
[0272] receiving system information of a frequency band that is
used in a small cell that is partially or entirely overlapped by a
macro cell when a terminal device is positioned within the macro
cell; and
[0273] acquiring information transmitted using radio resource as
the system information when the terminal device is positioned
within the macro cell and the radio resource that is used in
downlink transmission of the system information is notified of.
REFERENCE SIGNS LIST
[0274] 10 macro cell [0275] 20 pico cell [0276] 100 macro eNodeB
[0277] 110 antenna unit [0278] 120 wireless communication unit
[0279] 130 network control unit [0280] 140 storage unit [0281] 150
control unit [0282] 151 information acquisition unit [0283] 153
communication control unit [0284] 200 pico eNodeB [0285] 210
antenna unit [0286] 220 wireless communication unit [0287] 230
network control unit [0288] 240 storage unit [0289] 250 control
unit [0290] 251 communication control unit [0291] 253 information
provision unit [0292] 300 pico eNodeB [0293] 310 antenna unit
[0294] 320 wireless communication unit [0295] 330 storage unit
[0296] 340 control unit
* * * * *