U.S. patent application number 16/088302 was filed with the patent office on 2019-04-18 for user terminal, radio base station and radio communication method.
This patent application is currently assigned to NTT DOCOMO, INC.. The applicant listed for this patent is NTT DOCOMO, INC.. Invention is credited to Hiroki Harada, Huiling Jiang, Liu Liu, Satoshi Nagata, Lihui Wang.
Application Number | 20190116489 16/088302 |
Document ID | / |
Family ID | 59965831 |
Filed Date | 2019-04-18 |
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United States Patent
Application |
20190116489 |
Kind Code |
A1 |
Harada; Hiroki ; et
al. |
April 18, 2019 |
USER TERMINAL, RADIO BASE STATION AND RADIO COMMUNICATION
METHOD
Abstract
The present invention is designed to suitably realize UCI
(Uplink Control Information) transmission at a desired timing in a
carrier where LBT (Listen Before Talk) is configured. A user
terminal, according to one embodiment of the present invention, has
a transmission section that transmits signals in carriers where
listening is performed before uplink transmission, a receiving
section that receives PUCCH cell configuration information as to
whether or not at least one of the carriers is a cell where a PUCCH
(Physical Uplink Control Channel) is transmitted, and a control
section that controls the transmission of uplink control
information (UCI) in the carriers based on the PUCCH cell
configuration information.
Inventors: |
Harada; Hiroki; (Tokyo,
JP) ; Nagata; Satoshi; (Tokyo, JP) ; Liu;
Liu; (Beijing, CN) ; Wang; Lihui; (Beijing,
CN) ; Jiang; Huiling; (Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NTT DOCOMO, INC. |
Tokyo |
|
JP |
|
|
Assignee: |
NTT DOCOMO, INC.
Tokyo
JP
|
Family ID: |
59965831 |
Appl. No.: |
16/088302 |
Filed: |
March 30, 2017 |
PCT Filed: |
March 30, 2017 |
PCT NO: |
PCT/JP2017/013136 |
371 Date: |
September 25, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 72/0453 20130101;
H04W 74/0808 20130101; H04W 72/0413 20130101; H04W 72/042 20130101;
H04W 72/0446 20130101; H04W 74/006 20130101; H04W 8/22 20130101;
H04W 72/14 20130101; H04W 16/14 20130101 |
International
Class: |
H04W 8/22 20060101
H04W008/22; H04W 16/14 20060101 H04W016/14; H04W 74/08 20060101
H04W074/08; H04W 72/14 20060101 H04W072/14; H04W 72/04 20060101
H04W072/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2016 |
JP |
2016-073412 |
May 20, 2016 |
JP |
2016-101884 |
Claims
1. A user terminal comprising: a transmission section that
transmits signals in carriers where listening is performed before
uplink transmission; a receiving section that receives PUCCH cell
configuration information as to whether or not at least one of the
carriers is a cell where a PUCCH (Physical Uplink Control Channel
(PUCCH) is transmitted; and a control section that controls
transmission of uplink control information (UCI) in the carriers
based on the PUCCH cell configuration information.
2. The user terminal according to claim 1, wherein: the
transmission section transmits terminal capability information as
to whether or not PUCCH formats 4 and/or 5 are supported in at
least one of the carriers; and the terminal capability information
is used to control whether or not at least one of the carriers is
the cell where the PUCCH is transmitted.
3. The user terminal according to claim 1, wherein the receiving
section receives information as to whether or not simultaneous
transmission of the PUCCH and a Physical Uplink Shared Channel
(PUSCH) is possible, and the control section, when determining that
at least one of the carriers is the cell where the PUCCH is
transmitted, controls the transmission of the UCI in the carriers
based on the information as to whether or not the simultaneous
transmission is possible.
4. The user terminal according to claim 3, wherein the control
section controls the UCI to be retained for a predetermined period,
and the transmission section simultaneously transmits a plurality
of UCIs pertaining to the carriers and retained, in at least one of
the carriers.
5. The user terminal according to claim 1, wherein the receiving
section receives information about UCI transmission modes for
specifying whether UCI of each carrier is transmitted in a carrier
where listening is not carried out before uplink transmission, or
in a carrier where listening is performed before uplink
transmission, and the control section, when determining that none
of the carriers is the cell where the PUCCH is transmitted,
controls the transmission of UCI in the carriers based on the
information about UCI transmission modes.
6. The user terminal according to claim 5, wherein the control
section exerts control so that the UCI is retained for a first
retention period before downlink control information for
transmitting the UCI in the Physical Uplink Shared Channel (PUSCH)
is received, and retained for a second retention period after the
downlink control information is received, and the transmission
section simultaneously transmits a plurality of UCIs pertaining to
the carriers and retained, in at least one of the carriers, in the
PUSCH.
7. (canceled)
8. A radio communication method comprising the steps of:
transmitting signals in carriers where listening is performed
before uplink transmission; receiving PUCCH cell configuration
information as to whether or not at least one of the carriers is a
cell where a Physical Uplink Control Channel (PUCCH) is
transmitted; and controlling transmission of uplink control
information (UCI) in the carriers based on the PUCCH cell
configuration information.
9. A user terminal comprising: a receiving section that receives
downlink signals; a transmission section that transmits
retransmission control information in response to the downlink
signals in carries where listening is performed before
transmission; and a control section that determines a codebook size
to use to transmit the retransmission control information based on
a retention period for the retransmission control information.
Description
TECHNICAL FIELD
[0001] The present invention relates to a user terminal, a radio
base station and a radio communication method in a next-generation
mobile communication system.
BACKGROUND ART
[0002] In the UMTS Universal Mobile Telecommunications System)
network, the specifications of long-term evolution (LTE) have been
drafted for the purpose of further increasing high speed data
rates, providing lower delays and so on (see non-patent literature
1). Also, the specifications of LTE-A (also referred to as
LTE-advanced, LTE Rel. 10, 11 or 12, etc.) have been drafted for
further broadbandization and increased speed beyond LTE (also
referred to as LTE Rel. 8 or 9), and successor systems of LTE (also
referred to as, for example, FRA (Future Radio Access), 5G (5th
generation mobile communication system), LTE Rel. 13 and so on) are
under study.
[0003] The specifications of Rel. 8 to 12 LTE have been drafted
assuming exclusive operation in frequency bands that are licensed
to operators (also referred to as "licensed bands"). As licensed
bands, for example, 800 MHz, 1.7 GHz and 2 GHz are used.
[0004] In recent years, user traffic has been increasing steeply
following the spread of high-performance user terminals (UE: User
Equipment) such as smart-phones and tablets. Although more
frequency bands need to be added to accommodate this increasing
user traffic, licensed bands have limited spectra (licensed
spectra).
[0005] Consequently, a study is in progress with Rel. 13 LTE to
enhance the frequencies of LTE systems by using bands of unlicensed
spectra (also referred to as "unlicensed bands") that are available
for use apart from licensed bands (see non-patent literature 2).
For example, the 2.4 GHz band and the 5 GHz band, where Wi-Fi
(registered trademark) and Bluetooth (registered trademark) can be
used, are under study for use as unlicensed bands.
[0006] To be more specific, with Rel. 13 LTE, a study is in
progress to execute carrier aggregation (CA) between licensed bands
and unlicensed bands. Communication that is carried out by using
unlicensed bands with licensed bands like this is referred to as
"LAA" (License-Assisted Access). Note that, in the future, dual
connectivity (DC) between licensed bands and unlicensed bands and
stand-alone (SA) of unlicensed bands may become the subject of
study under LAA.
[0007] For unlicensed bands in which LAA is run, a study is in
progress to introduce interference control functionality in order
to allow co-presence with other operators' LTE, Wi-Fi or different
systems. In Wi-Fi, LBT (Listen Before Talk), which is based on CCA
(Clear Channel Assessment), is used as an interference control
function for use within the same frequency. LBT refers to the
technique of "listening" (sensing) before transmitting signals, and
controlling transmission based on the result of listening. For
example, in Japan and Europe, the LBT function is stipulated as
mandatory in systems that run in the 5 GHz unlicensed band such as
Wi-Fi.
CITATION LIST
Non-Patent Literature
[0008] Non-Patent Literature 1: 3GPP TS36.300 V8.12.0 "Evolved
Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal
Terrestrial Radio Access Network (E-UTRAN); Overall description;
Stage 2 (Release 8)," April 2010 [0009] Non-Patent Literature 2:
AT&T, "Drivers, Benefits and Challenges for LTE in Unlicensed
Spectrum, 3GPP TSG-RAN Meeting #62 RP-131701," Nov. 26, 2013
SUMMARY OF THE INVENTION
Technical Problem
[0010] Now, research is on-going to transmit uplink control
information (UCI) in cells of unlicensed bands. However, in cells
of unlicensed bands, whether or not transmission is possible
changes depending on the result of LBT, and, unless the UCI
transmission operation in unlicensed band cells is adequately
specified, UCI may not be transmitted at desired timing, and the
throughput of communication and/or the quality of communication may
be degraded.
[0011] The present invention has been made in view of the above,
and it is therefore an object of the present invention to provide a
user terminal, a radio base station and a radio communication
method, whereby UCI can be transmitted adequately, at desired
timing, in a carrier where LBT is configured.
Solution to Problem
[0012] According to one aspect of the present invention, a user
terminal has a transmission section that transmits signals in
carriers where listening is performed before uplink transmission, a
receiving section that receives PUCCH cell configuration
information as to whether or not at least one of the carriers is a
cell where a PUCCH (Physical Uplink Control Channel) is
transmitted, and a control section that controls transmission of
uplink control information (UCI) in the carriers based on the PUCCH
cell configuration information.
Technical Advantage of the Invention
[0013] According to the present invention, it is possible to
transmit UCI adequately, at a desired timing in a carrier where LBT
is configured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a diagram to explain the UCI transmission
operation according to embodiment 2.1;
[0015] FIG. 2 is a diagram to explain the UCI transmission
operation according to embodiment 2.2;
[0016] FIG. 3 is a diagram to illustrate an example of the UCI
retention operation according to an alternative example of a second
embodiment;
[0017] FIG. 4 is a diagram to illustrate examples of UCI
transmission modes according to a third embodiment;
[0018] FIGS. 5A and 5B are diagrams to illustrate examples of
transmission control in UCI transmission mode 1;
[0019] FIGS. 6A and 6B are diagrams to illustrate examples of
transmission control in UCI transmission mode 2;
[0020] FIGS. 7A and 7B are diagrams to illustrate examples of
transmission control in UCI transmission mode 3;
[0021] FIG. 8 is a diagram to illustrate an example of the UCI
retention operation in UCI transmission mode 3 according to the
third embodiment;
[0022] FIG. 9 is a diagram to illustrate another example of the UCI
retention operation in UCI transmission mode 3 according to the
third embodiment;
[0023] FIG. 10 is a diagram to illustrate yet another example of
the UCI retention operation in UCI transmission mode 3 according to
the third embodiment;
[0024] FIG. 11 is a diagram to illustrate an example of a schematic
structure of a radio communication system according to one
embodiment of the present invention;
[0025] FIG. 12 is a diagram to illustrate an example of an overall
structure of a radio base station according to one embodiment of
the present invention;
[0026] FIG. 13 is a diagram to illustrate an example of a
functional structure of a radio base station according to one
embodiment of the present invention;
[0027] FIG. 14 is a diagram to illustrate an example of an overall
structure of a user terminal according to one embodiment of the
present invention;
[0028] FIG. 15 is a diagram to illustrate an example of a
functional structure of a user terminal according to one embodiment
of the present invention;
[0029] FIG. 16 is a diagram to illustrate an example hardware
structure of a radio base station and a user terminal according to
one embodiment of the present invention;
[0030] FIG. 17 is a diagram to illustrate an example of the method
of determining the codebook size according to a fourth
embodiment;
[0031] FIG. 18 is a diagram to illustrate another example of the
method of determining the codebook size according to the fourth
embodiment; and
[0032] FIG. 19 is a diagram to illustrate another example of the
method of determining the codebook size according to the fourth
embodiment.
DESCRIPTION OF EMBODIMENTS
[0033] In systems that run LTE/LTE-A in unlicensed bands (for
example, LAA systems), interference control functionality is likely
to be necessary in order to allow co-presence with other operators'
LTE, Wi-Fi and/or other systems. Note that systems that run
LTE/LTE-A in unlicensed bands may be collectively referred to as
"LAA," "LAA-LTE," "LTE-U," "U-LTE" and so on, regardless of whether
the mode of operation is CA, DC or SA.
[0034] Generally speaking, when a transmission point (for example,
a radio base station (eNB), a user terminal (UE) and so on) that
communicates by using a carrier of an unlicensed band (which may
also be referred to as an "unlicensed cell," an "unlicensed CC,"
etc.) detects another entity (for example, another UE) that is
communicating in this unlicensed band carrier, the transmission
point is disallowed to make transmission in this carrier.
[0035] In this case, the transmission point executes listening
(LBT) at a timing that is a predetermined period ahead of
transmission timing. To be more specific, by executing LBT, the
transmission point searches the whole applicable carrier band (for
example, one component carrier (CC)) at a timing that is a
predetermined period ahead of a transmission timing, and checks
whether or not other devices (for example, radio base stations,
UEs, Wi-Fi devices and so on) are communicating in this carrier
band.
[0036] Note that, in the present specification, "listening" refers
to the operation which a given transmission point (for example, a
radio base station, a user terminal, etc.) performs before
transmitting signals, in order to check whether or not signals to
exceed a predetermined level (for example, predetermined power) are
being transmitted from other transmission points. Also, this
"listening" performed by radio base stations and/or user terminals
may be referred to as "LBT," "CCA," "carrier sensing" and so
on.
[0037] Also, for example, LBT that is performed by an eNB prior to
downlink transmission may be referred to as "DL LBT," and, for
example, LBT that is performed by a UE prior to uplink transmission
may be referred to as "UL-LBT." Information about the carrier where
UL-LBT is to be carried out may be reported to the UE, and, based
on this information, the UE may identify the carrier and execute
UL-LBT.
[0038] The transmission point then carries out transmission using
this carrier only if it is confirmed that no other apparatus is
communicating. For example, if the received power measured by LBT
(the received signal power during the LBT period) is equal to or
lower than a predetermined threshold, the transmission point
determines that the channel is in free state (LBT free) free and
carries out transmission. When a "channel is in free state," this
means that, in other words, the channel is not occupied by a
specific system, and it is equally possible to say that a channel
is "idle," a channel is "clear," a channel is "free," and so
on.
[0039] On the other hand, if only just a portion of the target
carrier band is detected to be used by another piece of apparatus,
the transmission point stops its transmission. For example, if the
transmission point detects that the received power of a signal from
another piece of apparatus in this band exceeds a predetermined
threshold, the transmission point determines the channel is in the
busy state (LBT.sub.busy), and makes no transmission. In the event
LBT.sub.busy is yielded, LBT is carried out again with respect to
this channel, and the channel becomes available for use only after
the free state is confirmed. Note that the method of judging
whether a channel is in the free state or in the busy state based
on LBT is by no means limited to this.
[0040] As LBT mechanisms (schemes), FBE (Frame Based Equipment) and
LBE (Load Based Equipment) are currently under study. Differences
between these include the frame configurations to use for
transmission/receipt, the channel-occupying time, and so on. In
FBE, the LBT-related transmitting/receiving configurations have
fixed timings. Also, in LBE, the LBT-related transmitting/receiving
configurations are not fixed in the time direction, and LBT is
carried out on an as-needed basis.
[0041] To be more specific, FBE has a fixed frame cycle, and is a
mechanism of carrying out transmission if the result of executing
carrier sensing for a certain period (which may be referred to as
"LBT duration" and so on) in a predetermined frame indicates that a
channel is available for use, and not making transmission but
waiting until the next carrier sensing timing if no channel is
available.
[0042] On the other hand, LBE refers to a mechanism for
implementing the ECCA (Extended CCA) procedure of extending the
duration of carrier sensing when the result of carrier sensing
(initial CCA) indicates that no channel is available for use, and
continuing executing carrier sensing until a channel is available.
In LBE, random backoff is required to adequately avoid
contention.
[0043] Note that the duration of carrier sensing (also referred to
as the "carrier sensing period") refers to the time (for example,
the duration of one symbol) it takes to gain one LBT result by
performing listening and/or other processes and deciding whether or
not a channel can be used.
[0044] A transmission point can transmit a predetermined signal
(for example, a channel reservation signal) based on the result of
LBT. Here, the result of LBT refers to information about the state
of channel availability (for example, "LBT.sub.free,"
"LBT.sub.busy," etc.), which is acquired by LBT in carriers where
LBT is configured.
[0045] Also, when a transmission point starts transmission based on
an LBT result that indicates the free state (LBT.sub.free) the
transmission point can skip LBT and still carry out transmission,
for a predetermined period (for example, for 10 to 13 ms). This
transmission is also referred to as "burst transmission," "burst,"
"transmission burst," and so on.
[0046] As described above, by introducing interference control that
is based on LBT mechanism and that is for use within the same
frequency to transmission points in LAA systems, it becomes
possible to prevent interference between LAA and Wi-Fi,
interference between LAA systems and so on. Furthermore, even when
transmission points are controlled independently per operator that
runs an LAA system, LBT makes it possible to reduce interference
without learning the details of each operator's control.
[0047] Also, in LTE/LTE-A, a user terminal (UE: User Equipment)
feeds back uplink control information (UCI) to a device on the
network side (which is, for example, a radio base station (eNB:
eNode B)). The UE transmits UCI by using an uplink control channel
(PUCCH: Physical Uplink Control Channel).
[0048] Also, at times where uplink data transmission is scheduled,
the UE may transmit UCI by using an uplink shared channel (PUSCH:
Physical Uplink Shared Channel). The radio base station performs
data retransmission control, scheduling control and so on, for the
UE, based on the UCI received.
[0049] UCI that is stipulated in LTE includes channel state
information (CSI), which is comprised of a channel quality
indicator (CQI), a precoding matrix indicator (PMI), a rank
indicator (RI) and so on, retransmission control information (also
referred to as "HARQ-ACK (Hybrid Automatic Repeat
reQuest-ACKnowledgment)," "ACK/NACK," "A/N," etc.), a scheduling
request (SR), and so on.
[0050] LAA systems are assumed to apply carrier aggregation to
cells of licensed bands (also referred to as "licensed carriers,"
"licensed CCs," etc.) and cells of unlicensed bands (also referred
to as "unlicensed carriers," "unlicensed CCs," etc.). Assuming this
case, a study is in progress to use unlicensed CCs as secondary
cells (SCells). Note that SCells that operate on unlicensed bands
may be referred to as "LAA SCells," for example.
[0051] While research is in progress to transmit UCI in LAA SCells,
there is an on-going discussion as to which cells' UCI is to be
transmitted in LAA SCells. For example, one idea under discussion
is not to transmit HARQ-ACKs pertaining to licensed CCs in the UL
for LAA SCells. This is because the throughput of licensed CCs will
decrease if HARQ-ACKs pertaining to licensed CCs cannot be sent due
to "LBT.sub.busy" and/or the like.
[0052] Also, a study is conducted to allow HARQ-ACKs and CSIs for
unlicensed CCs to be transmitted in the UL of LAA SCells. This is
to prevent the primary cell (PCell) of licensed CCs from entering
the overload state with a large amount of UCI.
[0053] It is not yet decided whether PUCCH can be used when UCI, or
even a part of UCI, is transmitted in unlicensed CCs, but it is
necessary to decide how to send UCI both when PUCCH is supported
and when PUCCH is not supported. In any case, it may be possible to
re-use part of existing UCI transmission control methods.
[0054] One existing UCI transmission control method is a method to
use PUCCH groups. With the PUCCH groups used in DC, eCA (enhanced
CA) and so on, up to two PUCCH groups are configured in a UE. It is
possible to configure one PUCCH cell in each group. A PUCCH cell
refers to a cell that is configured to transmit PUCCH. The UCI for
CCs in a given group can be transmitted in the PUCCH, using the
same group's PUCCH cell. Note that the PUCCH cell is not limited to
PCell.
[0055] Another existing method for controlling UCI transmission is
simultaneous transmission of PUCCH and PUSCH. For example, a UE
where simultaneous transmission of PUCCH and PUSCH (hereinafter
referred to as "PUCCH+PUSCH simultaneous transmission") is
configured (configured "true") can transmit HARQ-ACKs in PUCCH and
CSI in PUSCH, at the same time. Note that periodic CSI (P-CSI) may
be reported in the cell with the smallest cell index (for example,
an SCell index) among the cells where PUSCH is allocated, and
aperiodic CSI (A-CSI) may be reported in triggered cells.
[0056] For example, if PUCCH can be used in LAA SCells, it may be
possible to re-use existing concepts related to the design of PUCCH
groups. In this case, it may be possible to configure a PUCCH group
consisting only of licensed CCs and a PUCCH group consisting only
of unlicensed CCs, and transmit the UCI for each PUCCH group in the
PUCCH cells of that group. Note that PUCCH+PUSCH simultaneous
transmission may be configured per PUCCH group, individually.
Furthermore, the PUCCH groups may be referred to as "cell
groups."
[0057] However, in this case, in the unlicensed CCs, whether or not
PUCCH and/or PUSCH can be transmitted changes depending on what
result LBT indicates, and therefore how to define the UCI
transmission operation in the PUCCH group of unlicensed CCs raises
a problem.
[0058] Meanwhile, if PUCCH cannot be used in LAA SCells, how to
specify the UCI transmission operation in each CC, taking into
account the constraints of PUCCH+PUSCH simultaneous transmission,
LBT and so on, poses a problem. The reasons that PUCCH cannot be
used in LAA SCell may include, for example, that PUCCH is not
supported in the specification, that PUCCH is not configured
because PUCCH+PUSCH simultaneous transmission leads to a
power-limited state and makes it difficult to achieve sufficient
quality, and so on.
[0059] Also, although PUCCH+PUSCH simultaneous transmission between
different cells is already supported in licensed CCs, the operation
in unlicensed CCs has not been studied.
[0060] So, the present inventors have come up with the idea of
clearly defining the UCI transmission operation (transmission
control) in LAA SCells, both when PUCCH is used and when PUSCH is
used.
[0061] To do so, the present inventors have first started out with
the idea of configuring whether or not PUCCH transmission in LAA
SCells is possible via RRC (Radio Resource Control) signaling. In
addition, assuming the case where PUCCH transmission is configured,
the present inventors have come up with the idea of specifying
separate UE operations depending on whether or not PUCCH+PUSCH
simultaneous transmission is possible. In addition, the present
inventors have come up with the idea of defining UE operations in
multiple different UCI transmission modes when PUCCH transmission
is not configured, so that eNB can configure the UCI transmission
mode for the UE.
[0062] Now, embodiments of the present invention will be described
in detail below with reference to the accompanying drawings. For
each embodiment, a UE will be described to perform UL-LBT in LAA
SCells, but this is not limiting.
[0063] Also, although each embodiment will be described on the
assumption that CA is applied to PCell that is a license cell and
SCell that is an unlicensed cell, but this is not limiting.
[0064] That is, in each embodiment, the structure in which licensed
carriers are regarded as carriers where listening (LBT) is not
configured (which may be referred to as "carriers where LBT is not
executed," "carriers where LBT cannot be executed," "non-LBT
carriers," etc.), and the structure in which unlicensed carriers
are regarded as carriers where listening (LBT) is configured (which
may be referred to as "carriers where LBT is executed", "carriers
where LBT should be executed", "LBT carriers," etc.) also
constitute embodiments of the present invention.
[0065] Also, the combinations of carriers where LBT is not
configured and carriers where LBT is configured, and PCell and
SCells are not limited to those given above. For example, the
present invention can be applied to the case where a UE connects
with an unlicensed band in stand-alone (when PCell and SCells are
all carriers where LBT is configured), and so on.
[0066] (Radio Communication Method)
First Embodiment
[0067] According to the first embodiment of the present invention,
a UE reports information as to whether or not the UE supports
transmission in PUCCH format (PF: PUCCH Format) 4 and/or 5 (whether
or not to support PF 4/5) in LAA SCells, to the network side (for
example, eNB), as terminal capability information (UE
capability).
[0068] This capability information here may be reported using one
or a combination of the following: (1) Existing UE capability
information bits (capability bits) to indicate that PF 4/5 are
supported (these bits may be included and reported in, for example,
PhyLayerParameters-v13x0, which is specified as a parameter for LTE
Rel. 13); (2) New UE capability information bits to indicate that
PF 4/5 are supported in LAA SCells (these bits may be included, for
example, in PhyLayerParameters-v14x0, which is defined as a
parameter for LTE Rel. 14, and reported as UL-LAA-specific
information); (3) L-LAA UE capability information, including
capability information to indicate that PF 4/5 are supported in LAA
SCells (for example, included and reported in, for example,
supportOfLAA-r14 specified as a parameter for LTE Rel. 14).
[0069] Note that above (3) means that a UE that supports UL-LAA
always supports PF 4/5 in LAA SCells.
[0070] Also, the eNB may configure information as to whether to use
PUCCH in a given LAA SCell--that is, information about whether or
not a given LAA SCell is a PUCCH cell (PUCCH cell configuration
information--in the UE via higher layer signaling (for example, RRC
signaling). For example, whether or not an LAA SCell is a PUCCH
cell may be included in the information that is used to identify
the UE-specific physical channel configuration related to the SCell
(PhysicalConfigDedicatedSCell-r10), in the form of pucch-Cell-r14,
which is defined as a parameter for LTE Rel. 14, and reported to
the UE.
[0071] The PUCCH cell configuration information can also be seen as
information to indicate whether or not a given cell is a
PUCCH-transmitting cell. Note that, when at least one of the
above-described types of UE capability information is received from
a predetermined UE, the eNB may report PUCCH cell configuration
information to the UE.
[0072] According to the first embodiment described above, the eNB
can preferably controls the PUCCH configuration in LAA SCells based
on UE capability information transmitted from the UE.
[0073] Note that, although the first embodiment has been described
so that, when UCI for an LAA SCell is transmitted in PUCCH, whether
or not PUCCH transmission is supported in the LAA SCell is reported
by using UE capability information that indicates whether PF 4/5
are supported in the LAA SCell, on the assumption that only PF 4/5
are used as PUCCH formats, but this is by no means limiting.
[0074] For example, when a predetermined PF (for example, PF 2)
other than PF 4/5 is used in an LAA SCell, whether or not PUCCH
transmission is supported in the LAA SCell may be reported by using
UE capability information that indicates whether or not this
predetermined PF is supported in the LAA SCell. In addition,
information as to whether or not PUCCH transmission is supported in
the LAA SCell may be directly included and reported in the UE
capability information. In this case, when the eNB receives this
information from a predetermined UE, the eNB may perform control
assuming that the UE supports PF 4/5.
Second Embodiment
[0075] In the second embodiment of the present invention, the UE
operation in the case where PUCCH transmission (PUCCH on LAA SCell)
is configured in LAA SCells will be defined. Below, the second
embodiment will be roughly divided into two cases--namely, the case
where PUCCH+PUSCH simultaneous transmission is not possible
(configured "false") (embodiment 2.1) and the case where
PUCCH+PUSCH simultaneous transmission is possible (configured
"true") (embodiment 2.2)--and each case will be described.
Information as to whether or not simultaneous PUCCH+PUSCH
transmission is possible can be reported (configured) to a UE
through higher layer signaling (for example, RRC signaling).
[0076] In the second embodiment, as mentioned earlier, a PUCCH
group consisting only of licensed CCs and a PUCCH group consisting
only of unlicensed CCs are provided, and, when the UCI for each
PUCCH group is transmitted in PUCCH, it is transmitted in the PUCCH
cells of that group. However, the UCI transmission control
according to the second embodiment can be applied even if another
CC configuration and/or group configuration is configured in the
UE.
[0077] In the following description, only the UCI transmission
operation related to the PUCCH group (cell group) including
unlicensed CCs will be described, and the description of the PUCCH
group including licensed CCs will be omitted.
Embodiment 2.1
[0078] FIG. 1 is a diagram to explain the UCI transmission
operation according to embodiment 2.1. FIG. 1 illustrates three LAA
SCells. "PUCCH SCell" is an LAA SCell that is capable of PUCCH
transmission (configured as a PUCCH cell). "LAA SCell.sub.i" and
"LAA SCell.sub.i+1" are LAA SCells that cannot perform PUCCH
transmission (not configured as PUCCH cells). Assume that the SCell
index of LAA SCell.sub.i is smaller than that of either LAA
SCell.sub.i+1 or the PUCCH SCell. Note that application of this
embodiment is not limited to the case where a UE uses three LAA
SCells.
[0079] In FIG. 1, a UE executes listening in the CCA period before
transmitting UL signals in each SCell, and, upon judging that the
channel is idle, the UE carries out UL transmission. In addition,
periods t.sub.11 to t.sub.14 illustrated in FIG. 1 are simply
exemplary periods for explaining the UCI transmission operation,
and the order these periods occur, the length of these periods and
so on are not limited.
[0080] At a timing (for example, a TTI) where PUSCH is not
scheduled in either LAA SCell, the UCI for all of the unlicensed
CCs (in the PUCCH group) (including A/N, CSI (P-CSI, A-CSI, etc.),
SR and others) is transmitted (exemplified at t.sub.11) in the
PUCCHs of the LAA SCells based on LBT (PUCCH on LAA SCell).
However, A-CSI for SCells other than the PUCCH SCell may not be
transmitted in the PUCCH SCell.
[0081] Note that, referring to FIG. 1, UCI that needs not be
transmitted may not be transmitted even if it is illustrated in the
drawing. For example, at t.sub.11, at least one of A/N, CSI (P-CSI,
A-CSI, etc.) and SR may be transmitted. The same applies to the
other UCIs illustrated in the drawing, and the same applies to the
subsequent drawings.
[0082] The UE shall transmit PUCCH in PF 4/5 in the LAA SCells, but
other PFs may be used as well. Note that at a timing where only one
P-CSI is transmitted in PUCCH, the UE may transmit this one P-CSI
in accordance with PF 4 and/or 5, or transmit this one P-CSI in
accordance with an existing PF (for example, PF 2).
[0083] At a timing where PUSCH is scheduled in LAA SCells and A/N
and/or P-CSI is triggered (A/N and/or P-CSI is transmitted), the UE
transmits A/N and/or P-CSI based on LBT, in the PUSCH of a
particular cell among the LAA SCells that are scheduled
(exemplified at t.sub.12). In this case, the UE tries to transmit
UCI only in one of the LAA SCells that are scheduled, so that the
efficiency of the use of resources can be improved by not
transmitting redundant UCIs. At t.sub.12, the UE uses LAA
SCell.sub.i as the specific cell.
[0084] Here, the specific cell may be, for example, the cell where
a predetermined cell-related indicator is the smallest among the
LAA SCells that are scheduled. The predetermined indicator may be a
cell ID (cell identity), a physical cell ID, a virtual cell ID, a
cell index (for example, an SCell index, an index that is unique to
LAA SCells, etc.), or other indicators.
[0085] Also, at a timing where PUSCH is scheduled in LAA SCells and
A/N and/or P-CSI are triggered, the UE transmits A/N and/or P-CSI
based on LBT in the PUSCHs of all the scheduled LAA SCells
(exemplified at t.sub.13). In this case, the UE can try
transmitting UCI of the same contents in all of the LAA SCells that
are scheduled, so that the possibility that the UE will
successfully transmit the UCI can be improved.
[0086] Also, at a timing where PUSCH is scheduled in a
predetermined LAA SCell and A-CSI is triggered (A-CSI is
transmitted) in this LAA SCell, the UE transmits A-CSI based on
LTB, in the PUSCH of this LAA SCell (exemplified at t.sub.14). In
this case, the A-CSI is transmitted only in the A-CSI-triggered
cell, so that the communication overhead related to the reporting
of A-CSI can be distributed over each cell. In addition, when
having A/N that should be transmitted, the UE may transmit
(piggyback) the A-CSI and the A/N together.
Embodiment 2.2
[0087] FIG. 2 is a diagram to explain the UCI transmission
operation according to embodiment 2.2. FIG. 2 illustrates a similar
example to FIG. 1.
[0088] At a timing where at least one of A/N, P-CSI and SR should
be transmitted (for example, TTI), the UE transmits the UCI based
on the LBT in the PUCCH on the LAA SCell (PUCCH SCell) (illustrated
as t.sub.21, t.sub.23, t.sub.24 and t.sub.25).
[0089] FIG. 2 illustrates an example in which the UE transmits
PUCCH in PF 4/5 in LAA SCells, but different PFs may be used as
well. Note that at a timing where only one P-CSI is transmitted in
PUCCH, the UE may transmit this one P-CSI in PF 4 and/or 5, or
transmit this one P-CSI in an existing PF (for example, PF 2).
[0090] At a timing where A-CSI is triggered (A-CSI is transmitted),
the UE transmits A-CSI based on LBT using the PUSCH of the
triggered cell (exemplified at t.sub.22 and t.sub.25). For example,
at t.sub.22, A-CSI (A-CSI.sub.i) for LAA SCell.sub.i is transmitted
in LAA SCell.sub.i.
Alternative Example of Second Embodiment
[0091] When UCI is transmitted in an unlicensed CC, there is a
possibility that LBT fails (the result of LBT indicates "busy") and
a delay is produced before PUCCH and/or PUSCH are transmitted. When
transmission of UCI is delayed and the UCI that is already
generated is immediately discarded, unnecessary UCI generation
processing might take place in the UE, and the processing load in
the UE may increase.
[0092] So, the UE may retain the UCI for a predetermined period
(which may be referred to as "UCI retention period," "PUCCH-related
UCI retention period," etc.). By this means, the UE can transmit
all the UCI that has been retained, at the time LBT succeeds (the
result of LBT indicates "free"). For example, UCI may be retained
by storing UCI in a predetermined buffer area.
[0093] The UCI retention period may be defined as a period, which
starts from the time resource of a PUCCH that may be able to
transmit given UCI first (for example, TTI), and in which this UCI
can be transmitted in the PUCCH. Also, the UCI retention period may
be defined with a fixed value in advance in the specification, or
may be reported from the eNB by using higher layer signaling (for
example, RRC signaling, broadcast information (MIB (Master
Information Block), SIB (System Information Block), etc.), physical
layer signaling (for example, downlink control information (DCI)),
or a combination of these.
[0094] Note that, once UCI is successfully transmitted, the UCI
discards this UCI even during the UCI retention period. Meanwhile,
even after UCI is successfully transmitted, the UE may retain this
UCI during the UCI retention period.
[0095] FIG. 3 is a diagram to illustrate an example of the UCI
retention operation according to an alternative example of the
second embodiment. FIG. 3 illustrates downlink signals (DL Tx)
received in a UE, uplink resources for a PUCCH SCell and UCIs (A/N)
that are transmitted. FIG. 3 assumes a TTI duration of 1 ms, but
the TTI duration is not limited to this.
[0096] In FIG. 3, the UE receives downlink signals (downlink data)
in twelve consecutive TTIs. an A/N (A/N.sub.j) is generated in
response to the receipt of a downlink signal in the j-th TTI, and
retained. In this way, every time the UE receives a downlink
signal, the UE generates an A/N in response, and retains this. In
FIG. 3, the UCI retention period (X) is configured to 9 ms.
Consequently, each A/N.sub.j is discarded after it is retained for
9 ms. That is, it is possible to say that the maximum number of
UCIs (A/Ns) that can be retained in the buffer is the value given
by dividing the UCI retention period by the TTI duration.
[0097] The UE performs LBT-based UL transmission (including UCI
transmission) using PUCCH, in an XSCell, a predetermined period of
time (for example, 4 ms) after downlink data is received. Note
that, since the "UCI to be transmitted" cannot be transmitted
depending on the result of LBT (for example, in TTIs where "X"
overlaps "UL" in the drawing), there are cases where "UCI scheduled
to be transmitted" is indicated. According to this example, even
after UCI is successfully transmitted, the UCI is retained during
the UCI retention period, and transmission continues during the
retention period.
[0098] In this example, the UE can transmit UCI as long as the UCI
retention period (X) continues, and therefore the possibility that
each UCI can transmit each UCI in an LAA SCell (XSCell) can be
improved.
[0099] Note that, although FIG. 3 illustrates an example in which
UCI is transmitted in PUCCH, this is not limiting. For example,
even when the UE transmits UCI in PUSCH, or transmits UCI in PUCCH
and in PUSCH, the UE may likewise control the UCI transmission
process based on the UCI retention period.
[0100] Also, the UCI retention period may be configured/specified
individually for each type of UCI. For example, the UCI retention
period for A/Ns, the UCI retention period for P-CSI, the UCI
retention period for A-CSI and the UCI retention for the SR period
may be configured/defined differently, or may be configured/defined
the same.
Third Embodiment
[0101] A third embodiment of the present invention will define the
UE operation in the case where PUCCH transmission is not configured
in an LAA SCell (PUCCH on LAA SCell).
[0102] In the third embodiment, a plurality of UCI transmission
modes (UCI Tx (Transmission) modes) will be defined, which are used
to specify whether to transmit the UCI of each CC in a licensed
carrier or an unlicensed carrier. Then, the eNB configures
(reports) based on which UCI transmission mode the UE should
perform transmission control, via higher layer signaling (for
example, RRC signaling), physical layer signaling (for example,
DCI), or a combination of these.
[0103] FIG. 4 is a diagram to illustrate examples of UCI
transmission modes according to the third embodiment. UCI
transmission mode 0 is a mode of sending all the UCI related to the
unlicensed CC in the licensed CC. In UCI transmission mode 1, only
the A-CSI related to the unlicensed CC is sent in the unlicensed
CC, and the rest of the UCI is sent in the licensed CC. In UCI
transmission mode 2, CSI (P-CSI and A-CSI) related to the
unlicensed CC is sent in the unlicensed CC, and the A/N related to
the unlicensed CC is sent in the licensed CC. UCI transmission mode
3 is a mode of sending all the UCI related to the unlicensed CC in
the unlicensed CC.
[0104] Although not illustrated in FIG. 4, an SR pertaining to the
unlicensed CC may be transmitted, for example, in the CC where an
A/N for the unlicensed CC is transmitted, may be transmitted in the
licensed CC at all times, or may be transmitted in the CC where the
rest of the UCI is transmitted.
[0105] Hereinafter, points of each transmission mode according to
the third embodiment that are of particular importance will be
described in detail. Transmission control for UCI not specifically
mentioned in each transmission mode may be the same as the
transmission control in eCA of LTE Rel. 13.
[0106] Note that FIG. 5 to FIG. 7, which will be used in the
following description, illustrate a PCell, which is a licensed CC,
and a licensed SCell.sub.n, LAA SCell (and LAA SCell.sub.i+1),
which is an unlicensed CC, and uplink signals for each cell. LAA
SCell.sub.i is the cell with the smallest SCell index among LAA
SCells. Note that PCell can also be referred to as the PUCCH cell
of licensed carriers.
[0107] [UCI Transmission Mode 0]
[0108] In UCI transmission mode 0, in which in licensed CC A-CSI
relating to an unlicensed CC is to be transmitted may be defined in
the specification in advance, or may be configured in the UE via
RRC signaling and so on.
[0109] [UCI Transmission Mode 1]
[0110] FIG. 5 provide diagrams to illustrate examples of
transmission control according to UCI transmission mode 1. In UCI
transmission mode 1, where PUCCH+PUSCH simultaneous transmission is
not possible, at a timing where PUSCH is scheduled only in the
unlicensed CC, the UE drops the P-CSI for the unlicensed CC (FIG.
5A). FIG. 5A illustrates an example of dropping the P-CSI
(P-CSI.sub.i) for LAA SCell.sub.i at a timing where PUSCH is
scheduled only in LAA SCell.sub.i.
[0111] Also, in UCI transmission mode 1 where PUCCH+PUSCH
simultaneous transmission is not possible, at a timing where PUSCH
is scheduled only in the unlicensed CC and PF 3 is used in the
PCell, the UE drops the P-CSI for the unlicensed CC (FIG. 5B).
[0112] Note that, in UCI transmission mode 1, as illustrated in
FIG. 5, at a timing where PUSCH is scheduled in the licensed CC,
the UE can transmit the P-CSI for the unlicensed CC in the PUSCH of
the licensed CC.
[0113] [UCI Transmission Mode 2]
[0114] In UCI transmission mode 2, the UE may transmit P-CSI
pertaining to the unlicensed CC only in the PUSCH of a specific
cell or in the PUSCHs of all the LAA SCells that are scheduled.
Here, the specific cell may be, for example, the cell where a
predetermined cell-related indicator is the smallest among the LAA
SCells scheduled. The predetermined indicator may be a cell ID, a
physical cell ID, a virtual cell ID, a cell index (for example, an
SCell index, an index that is unique to LAA SCells, etc.), or other
indicators.
[0115] FIG. 6 provide diagrams to illustrate examples of
transmission control in accordance with UCI transmission mode 2.
FIG. 6A illustrates a case where PUCCH+PUSCH simultaneous
transmission is not possible, and FIG. 6B illustrates a case where
PUCCH+PUSCH simultaneous transmission is possible. In FIG. 6,
regardless of whether or not PUCCH+PUSCH simultaneous transmission
is possible, P-CSI for all unlicensed CCs is transmitted in the
PUSCH of LAA SCell.sub.i.
[0116] [UCI Transmission Mode 3]
[0117] In UCI transmission mode 3, the UE controls the transmission
of UCI using a newly defined operation. First, one specific LAA
SCell is selected as a special LAA SCell for transmitting UCI. This
special LAA SCell may be referred to as "XSCell," for example.
[0118] The UE may select XSCell and report information that
represents this XSCell to the eNB. The report may be sent, for
example, via higher layer signaling (for example, RRC signaling),
physical layer signaling (UCI), or a combination of these. The UE
may select XSCell based on the history of LBT results, for
example.
[0119] Also, the eNB may select XSCell and report information that
represents this XSCell to the UE. The report may be sent, for
example, via higher layer signaling (for example, RRC signaling),
physical layer signaling (for example, DCI such as a UL grant), or
a combination of these.
[0120] The eNB may select XSCell using or based on, for example,
one or a combination of following (a) to (d):
[0121] (a) uniform and random selection;
[0122] (b) A/Ns for each carrier;
[0123] (c) history of UL-LBT results reported from the UE; and
[0124] (d) when type-B multicarrier LBT is used for UL-LBT, a CC
that is selected to implement LBT category 4 (LBT to which random
backoff is applied) and XSCell are associated.
[0125] The UE transmits A/Ns and/or P-CSI for the unlicensed CC
only in the PUSCH of XSCell based on LBT. Here, if PUCCH+PUSCH
simultaneous transmission is not possible, the UE transmits the UCI
(A/Ns and/or P-CSI) in the unlicensed CC only at timings where
there is no PUCCH transmission in the licensed CC. On the other
hand, if PUCCH+PUSCH simultaneous transmission is possible, the UE
transmits the UCI in the unlicensed CC, regardless of the licensed
CC.
[0126] FIG. 7 provide diagrams, illustrating examples of
transmission control according to UCI transmission mode 3. FIG. 7A
illustrates a case where PUCCH+PUSCH simultaneous transmission is
not possible, and FIG. 7B illustrates a case where PUCCH+PUSCH
simultaneous transmission is possible. XSCell is LAA SCell.sub.i in
FIG. 7A and LAA SCell.sub.i+1 in FIG. 7B.
[0127] In FIG. 7A, at a timing where there is no PUCCH transmission
in the licensed CC, the unlicensed CC's A/N is transmitted in
XSCell, and this cell's A-CSI (A-CSI.sub.i) of the cell is
transmitted in LAA SCell Note that the UE gives priority to PUCCH
at a timing where there is PUCCH transmission in the licensed
CC.
[0128] In FIG. 7B, the UE transmits the UCI of the licensed CC in
the licensed CC (PCell or PUCCH cell) and transmits A/N and P-CSI
for the unlicensed CC in the PUSCH of XSCell. The UE transmits the
unlicensed CC's A-CSI in a measurement-triggered cell.
[0129] In UCI transmission mode 3, the UE may retain the UCI (for
example, A/N and P-CSI) for the unlicensed CC for a predetermined
period (which may be referred to as "UCI retention period (time
window for UCI retention)," "first retention period (first UCI
retention period related to PUSCH)," and so on). When the
opportunity to transmit PUSCH arrives during the first retention
period, the UE transmits all the UCI that has been retained all
together. Meanwhile, the UE discards the UCI that has passed the
first retention period.
[0130] The first retention period may be defined as a period in
which transmission of certain UCI (for example, A/N bit) in PUSCH
is valid. Also, the first retention period may be pre-defined in
the specification using fixed values, or may be reported from the
eNB by higher layer signaling (for example, RRC signaling),
physical layer signaling (DCI such as a DL grant), or a combination
of these.
[0131] Note that the UE retains an A/N during the first retention
period, even when no uplink resource-scheduling UL grant is
received. The first retention period may start from the first time
resource (for example, TTI) of XSCell's PUSCH where UCI may be
transmitted, or start from the TTI where given UCI is generated
(for example, a TTI where a DL signal is received).
[0132] Also, even when a UL grant is received, there is a
possibility that LBT will fail and UCI transmission will be
delayed. Therefore, in UCI transmission mode 3, the UE may retain
the UCI (for example, A/N and P-CSI) for the unlicensed CC for a
predetermined period (also referred to as "time window for UCI
transmission," "second retention period (second UCI retention
period on PUSCH)," etc.), which is different from the
above-mentioned UCI retention period.
[0133] The second retention period may be defined as a period which
starts from the first time resource (for example, TTI) of XSCell's
PUSCH where given UCI may be transmitted, and in which this UCI can
be transmitted in XSCell's PUSCH. Also, the second retention period
may be pre-defined in the specification using fixed values, or may
be reported from the eNB by higher layer signaling (for example,
RRC signaling), physical layer signaling (DCI such as a DL grant),
or a combination of these.
[0134] Note that, as for the retention period for predetermined UCI
(for example, A/N), the one with the larger value between the first
retention period (for example, Y ms) and the second retention
period (for example, X ms) may be used, or it is equally possible
to use the retention period until a UL grant is received as the
first retention period, and use the retention period after a UL
grant is received (after a transmission starting timing based on
the receipt of a UL grant) as the second retention period.
[0135] Furthermore, either the retention period until a UL grant is
received or the retention period after a UL grant is received may
be set as the first retention period (or second retention period).
In this case, the UE may exert control so that, when a UL grant is
received, the time that has passed since the retention of each
retained UCI started is reset.
[0136] Note that, once UCI is transmitted successfully, the UE may
discard this UCI even during the UCI retention period. On the other
hand, even after UCI is transmitted successfully, the UE may retain
this UCI during the UCI retention period.
[0137] Also, the UCI retention period, the first retention period,
the second retention period and others may be individually
configured/defined for each type of UCI.
[0138] FIG. 8 is a diagram to illustrate an example of the UCI
retention operation in UCI transmission mode 3 according to the
third embodiment. FIG. 8 illustrates downlink signals (DL Tx)
received by the UE, UL grants received by the UE, uplink resources
for the PUSCH of XSCell, and UCIs (A/Ns) that are transmitted based
on UL grants.
[0139] FIG. 8 assumes a TTI duration of 1 ms, but the TTI duration
is not limited to this. The same applies to FIG. 9 and FIG. 10
below.
[0140] In FIG. 8, the UE receives downlink signals (downlink data)
in twelve consecutive TTIs. an A/N (A/N.sub.j) is generated in
response to the receipt of a downlink signal in the j-th TTI, and
retained. In this way, every time the UE receives a downlink
signal, the UE generates an A/N in response, and retains this. In
FIG. 8, the UCI retention period (X) is configured to 9 ms.
Consequently, each A/N.sub.j is discarded after it is retained for
9 ms.
[0141] Also in FIG. 8, in TTIs where the UE receives downlink data,
the UE also receives UL grants that schedule XSCell's uplink
transmission. In FIG. 8, each UL grant schedules transmission of a
transport block in one subframe (single-subframe scheduling).
[0142] The UE performs LBT-based UL transmission (including
transmission of UCI) in XSCell a predetermined period of time (for
example, 4 ms) after a UL grant is received. In this example, even
UCI that has been successfully transmitted is retained during the
UCI retention period. The same applies to the examples of FIG. 9
and FIG. 10.
[0143] In this example, the UE can transmit UCI as long as the UCI
retention period (X) continues, so that the possibility that the UE
can transmit each UCI can be improved.
[0144] FIG. 9 is a diagram to illustrate another example of the UCI
retention operation in UCI transmission mode 3 according to the
third embodiment. FIG. 9 illustrates downlink signals (DL Tx)
received by the UE, UL grants received by the UE, uplink resources
for the PUSCH of XSCell, and UCIs (A/Ns) that are transmitted based
on UL grants.
[0145] In FIG. 9, the UE receives downlink signals (downlink data)
in twelve consecutive TTIs, as in the example of FIG. 8. In FIG. 9,
the first retention period (Y) is configured to 6 ms, and the
second retention period (X) is configured to 9 ms. Consequently,
each A/N.sub.j is discarded after it is retained for 9 ms.
[0146] Furthermore, in FIG. 9, in the TTIs where the sixth and
twelfth downlink signals are transmitted, UL grants are
transmitted. In FIG. 9, each UL grant schedules the transmission of
transport blocks in multiple subframes (multi-subframe
scheduling).
[0147] In this example, a UL grant commands the transmission of UL
subframes in a number of TTIs to match second retention period, so
that it is possible to improve the possibility that the UE can
transmit each UCI.
[0148] FIG. 10 is a diagram to illustrate yet another example of
the UCI retention operation in UCI transmission mode 3 according to
the third embodiment. FIG. 10 illustrates downlink signals (DL Tx)
received by the UE, UL grants received by the UE, UCIs (A/Ns) that
are retained for transmission (awaiting transmission), UCIs (A/Ns)
that are transmitted based on UL grants.
[0149] FIG. 10 illustrates an example in which the eNB tries to
transmit downlink signals (downlink data) in twelve consecutive
TTIs, and in which the eNB nevertheless fails to transmit some of
the downlink signals cannot be transmitted because the LBT result
indicated a busy state. In FIG. 10, the first retention period (Y)
is configured to 6 ms, and the second retention period (X) is not
configured. Consequently, each A/N.sub.j is discarded when 6 ms
pass without receiving a UL grant, or when 6 ms pass after
transmission is ready.
[0150] At the transmission timing based on the first UL grant
illustrated in FIG. 10, A/N.sub.1 to A/N.sub.4 are retained as UCIs
that can be transmitted. Also, at the transmission timing based on
the second UL grant illustrated in FIG. 10, A/N.sub.4 to A/N.sub.6
are retained.
[0151] As explained in this example, even when UL grants cannot be
received, it is still possible to improve the possibility that the
UE, where the first retention period (Y) is configured, can
transmit each UCI.
[0152] Note that the UCIs to retain are not limited to A/N and
P-CSI. For example, the transmission of at least one of A/N, P-CSI,
A-CSI and SR may be controlled based on the first retention period
and/or the second retention period.
[0153] [Control Signal for UCI Transmission Mode]
[0154] It may be possible to use a UL grant, a PDCCH that is
transmitted in a common search space (common PDCCH) and so on, as a
control signal for configuring the UCI transmission modes described
in the third embodiment in the UE.
[0155] For example, information about UCI transmission modes may be
reported using a UL grant. As this information, for example,
two-bit information to represent UCI transmission modes 0 to 3 may
be used.
[0156] Furthermore, information for specifying the special LAA
SCell (XSCell) for UCI transmission in UCI transmission mode 3 may
be reported using a UL grant. For this information, information of
a predetermined number of bits may be used (where the predetermined
number is, for example, the number of LAA SCells, the maximum
number of LAA SCells, etc.).
[0157] Furthermore, information about the first retention period
and/or the second retention period in UCI transmission mode 3 may
be reported in a common PDCCH (for example, DCI format 1C). The
common PDCCH may be transmitted in the PCell, or may be transmitted
in an SCell of a licensed CC and/or an LAA SCell.
[0158] Note that, in order to command these pieces of UCI
mode-related control information, new fields may be set forth in
DCI formats, or may replace existing fields (for example, the
resource allocation field) and be used.
Fourth Embodiment
[0159] With a fourth embodiment of the present invention, the
codebook size (also referred to as "CBS," "HARQ codebook size,"
etc.) for use when HARQ-ACK transmission is carried out in LAA
SCells will be explained. Note that, although PUCCH transmission is
not configured in LAA SCells (PUCCH on LAA SCell) in the case
described below, UCI such as HARQ-ACK is transmitted in PUSCH.
However, the present embodiment is not limited to this, and can
also be applied to cases where PUCCH transmission is performed.
[0160] When sending HARQ-ACK in response to DL transmission, the
user terminal transmits the HARQ-ACK in a predetermined codebook
size (also referred to as "ACK/NACK bit sequence," "A/N bit size,"
etc.). In existing systems, the codebook size of HARQ-ACK (ACK/NACK
bit sequence) to be transmitted in PUCCH is determined
semi-statically based on information about the number of CCs
reported by higher layer signaling.
[0161] When FDD is used, the overall A/N bit size is determined
based on the number of CCs configured by RRC signaling, and based
on TM (Transmission Mode), which indicates whether or not MIMO
(Multiple Input Multiple Output) is applicable in each CC. In a
given DL subframe, if a DL assignment is detected in at least one
SCell, the user terminal feeds back A/Ns in response to all the CCs
that are configured, in the UL subframe that comes a predetermined
period later (for example, 4 ms later).
[0162] When TDD is used, in addition to the above case of using
FDD, the overall size of the A/N bit sequence to transmit in PUCCH
is determined based on the number of DL subframes that pertain to
A/N per UL subframe.
[0163] Meanwhile, as mentioned above, when A/N transmission is
controlled so that an A/N is retained for a predetermined period of
time in LAA SCells, how to configure the codebook size is the
problem. Since existing systems do not assume that A/Ns are
retained, if existing methods are applied on an as-is basis, it may
not be possible to configure the codebook size adequately. In this
way, another problem which the present invention addresses is how
to appropriately configure the codebook size when performing
HARQ-ACK transmission in LAA SCells.
[0164] So, the present inventors have come up with the idea of
determining the codebook size of HARQ-ACK by taking into account
the retention period of A/Ns, when transmitting HARQ-ACK in LAA
SCells. Hereinafter, the case where the codebook size is fixedly
configured (fixed codebook size) and the case where the codebook
size is dynamically configured (dynamic codebook size) when
HARQ-ACK transmission is performed in LAA SCells will be
described.
[0165] According to the fourth embodiment, the user terminal
transmits A/Ns (retransmission control information) in response to
downlink signals in LAA SCells (carriers where listening is
performed before transmission). The user terminal configures the
codebook size to use to transmit an A/N based on the time the user
terminal retains this A/N.
[0166] [Fixed Codebook Size]
[0167] When using a fixed codebook size, the user terminal may
configure a fixed codebook size based on the period the A/N is
retained in the user terminal (A/N retention period). Here, the A/N
retention period may be at least one of the period A/N is retained,
starting from a TTI that is scheduled by a UL grant (second
retention period (X)), and the period in which an A/N in response
to a downlink signal is retained, starting from the TTI in which
the downlink signal is received (first retention period (Y)).
[0168] The user terminal retains an A/N for the second retention
period (X), which starts from a TTI scheduled by a UL grant.
Therefore, even when the user terminal fails listening in this
scheduled TTI, if the user terminal succeeds in listening in a
subsequent TTI within the second retention period (X), the user
terminal can transmit the A/N. After the second retention period
(X) is over, the user terminal discards the A/N.
[0169] Also, the user terminal retains an A/N for the first
retention period (Y) from a TTI in which a downlink signal is
received. Consequently, even when the user terminal does not
receive a UL grant in this TTI in which a downlink signal is
received (downlink data, a downlink data channel (for example,
PDSCH (Physical Downlink Shared Channel)), etc.), if the user
terminal successfully receives a UL grant in a subsequent TTI
within the first retention period (Y), the user terminal can
transmit the A/N in the TTI scheduled by this UL grant. When the
first retention period (Y) is over, the user terminal discards the
A/N.
[0170] Note that, when the first retention period (Y) is equal to
the TTI duration (for example 1 ms), this may be interpreted to
mean that the first retention period (Y) is not configured. In this
case, if the user terminal does not receive a UL grant in a TTI in
which a downlink signal was received, the user terminal cannot
transmit an A/N in response to the downlink signal.
[0171] Also, the user terminal may configure the fixed codebook
size based on the number of CCs (cells), in addition to the
above-described A/N retention period (at least one of the first
retention period (Y) and the second retention period (X)). Here,
the number of CCs has to be the number of cells (CCs) where A/Ns
need to be transmitted in response to downlink signals, but is not
limited to the number of LAA SCells or the number of CCs configured
in the user terminal. Also, the number of CCs may be the number of
CCs in a UCI cell group.
[0172] For example, the user terminal may configure a fixed
codebook size based on following equation 1:
CBS=[X/Y]YN (Equation 1)
where X is the second retention period described above, Y is the
first retention period described above, and N is the number of
cells (CC) where A/Ns are generated in response to downlink
signals. Note that equation 1 is simply an example, and this is by
no means limiting. Various parameters that are not indicated in
equation 1 may be taken into account.
[0173] Also, although above X, Y and N are configured via higher
layer signaling, these may be specified through physical layer
signaling, or determined by a combination of higher layer signaling
and physical layer signaling. Also, the CBS itself may be
configured via higher layer signaling, or may be specified through
physical layer signaling.
[0174] FIG. 17 is a diagram to illustrate an example of the method
of determining the codebook size according to the fourth
embodiment. FIG. 17 illustrates downlink signals (DL Tx) received
by the UE, UL grants received by the UE, uplink resources for the
PUSCH of XSCell, UCIs (A/Ns) that are transmitted based on UL
grants, A/Ns retained in each TTI based on the first retention
period (Y), and A/Ns retained in each TTI based on the second
retention period (X).
[0175] In FIG. 17, the TTI duration is 1 ms, but the TTI duration
is not limited to this. The same applies to FIG. 18 and FIG. 19
below. Furthermore, although, in FIG. 17, a UL grant schedules UL
transmission in the TTI that comes four TTIs later, UL transmission
to be scheduled by a UL grant is not limited to four TTIs
later.
[0176] Also, although FIG. 17 illustrates a case of single-subframe
scheduling, in which UL transmission is scheduled in a single
subframe by a UL grant in a single subframe, multi-subframe
scheduling can be applied as well, in which UL transmission is
scheduled in a plurality of subframes by that UL grant.
[0177] Also, in FIG. 17, the first retention period (Y) is
configured to 6 ms, and the second retention period (X) is
configured to 9 ms. Note that the configuration values of the first
retention period (Y) and the second retention period (X) are not
limited to these. The configuration values of the first retention
period (Y) and the second retention period (X) may each be n (n 1)
times the TTI duration. For example, if the first retention period
(Y) is not configured (in the event control is exerted so that,
unless a UL grant is received in a TTI in which a downlink signal
is received, no A/N is transmitted in response to this downlink
signal), Y=TTI duration (for example, 1 ms) may be used.
[0178] In addition, in FIG. 17, the number (N) of cells (CCs) where
A/Ns are generated in response to downlink signals is configured to
1, but this is not limiting. In FIG. 17, the fixed codebook size
determined using above equation 1 is 12 (=261).
[0179] In FIG. 17, the user terminal receives downlink signals
(downlink data) in 18 consecutive TTIs. When a downlink signal is
received in the j-th TTI, A/N.sub.j is generated in response to
this downlink signal. The user terminal retains the generated
A/N.sub.j for the first retention period (Y) (here, for 6 ms). For
example, A/N.sub.1 in response to the downlink signal of the first
TTI is retained from the first TTI to the sixth TTI, and discarded
if no UL grant is received by the sixth TTI.
[0180] Thus, A/N.sub.j in response to the downlink signal of the
j-th TTI is retained from the j-th TTI to the j+(Y-1)-th TTI.
A/N.sub.j is discarded unless a UL grant is received before the
j+(Y-1)-th TTI. On the other hand, when a UL grant is received by
the j+(Y-1)-th TTI, A/N.sub.j is transmitted using the PUSCH
scheduled by this UL grant.
[0181] In FIG. 17, when a UL grant is received in the sixth TTI,
A/N.sub.1 to A/N.sub.6 in response to the downlink signals of the
first to sixth TTIs are retained based on the first retention
period (Y), so that transmission of A/N.sub.1 to A/N.sub.6 is
attempted in the tenth TTI scheduled by the UL grant. Meanwhile,
the user terminal may not succeed in LBT in or immediately before
the tenth TTI. So, the user terminal retains A/N.sub.1 to A/N.sub.6
for the second retention period (X) (here, for 9 ms) from the tenth
TTI scheduled by the UL grant. In FIG. 17, since LBT succeeds in or
immediately before the tenth TTI, A/N.sub.1 to A/N.sub.6 are
transmitted in this tenth TTI, using six bits out of the twelve
bits of the codebook. In this case, the remaining six bits that are
not used may be, for example, configured in default values (for
example, NACK).
[0182] Also, at the time a UL grant is received in the twelfth TTI,
A/N 7 to A/N.sub.12 in response to the downlink signals of the
seventh to twelfth TTI are retained based on the first retention
period (Y). Furthermore, in the sixteenth TTI scheduled by the UL
grant, in addition to A/N.sub.7 to A/N.sub.12 above, A/N.sub.1 to
A/N.sub.6 in response to the downlink signals of the first to sixth
TTIs are retained based on the second retention period (X).
Therefore, in the sixteenth TTI, A/N.sub.1 to A/N.sub.12 are
transmitted using all bits of the twelve-bit codebook.
[0183] Also, at the time a UL grant is received at the eighteenth
TTI, A/N.sub.13 to A/N.sub.18 in response to the downlink signals
of the thirteenth to eighteenth TTIs are retained based on the
first retention period (Y). Furthermore, in the sixteenth TTI
scheduled by the UL grant, in addition to A/N.sub.13 to A/N.sub.18
above, A/N.sub.7 to A/N.sub.12 in response to the downlink signals
of the seventh to twelfth TTIs are retained based on the second
retention period (X). Accordingly, in the twentieth TTI, A/N.sub.7
to A/N.sub.18 are transmitted using all bits of the twelve-bit
codebook.
[0184] As described above, when the codebook size of each TTI is
set in a fixed size that is equal to the maximum possible number of
A/Ns, it is possible to simplify the control of the codebook size
in the user terminal.
[0185] [Dynamic Codebook Size]
[0186] When dynamically changing the codebook size, the codebook
size is determined taking the A/N retention period into account
(for example, the second retention period (X)). For example, when
UL transmission is performed in a given subframe (SF #n), the
codebook size is controlled based on whether or not there is a UL
subframe in a range of a predetermined period going backward from
this SF #n. The UL subframe here refers to a UL subframe in which
at least HARQ-ACK has been transmitted (including cases where
transmission is not allowed due to LBT results). Also, the
predetermined period can be a range that takes into account the A/N
retention period (for example, X-1 or less). Of course, X-1 is not
limiting.
[0187] The user terminal changes the codebook size depending on
whether or not there is a UL subframe (for example, SF #m) in which
HARQ-ACK is transmitted, within a range that goes (X-1) ms backward
from SF #n where HARQ-ACK is transmitted. To be more specific, when
there is a UL subframe (SF #m) in which HARQ-ACK is transmitted
within the range back to (X-1) ms before SF #n in which HARQ-ACK
transmission is performed, the user terminal determines the
codebook size of SF #n, by additionally taking into account the
codebook size of HARQ-ACK of SF #m. Note that there may be more
than one SF #m.
[0188] In this case, the user terminal can determine the codebook
size of SF #n regardless of the result of LBT in SF #m (based only
on the position of SF #m). Alternatively, the codebook size in SF
#n may be controlled, taking into account the result of UL
transmission (LBT result) in SF #m. For example, a structure may be
employed here in which, to decide the codebook size in SF #n when
an A/N is successfully transmitted in SF #m (LBT idle), the
codebook size of SF #m is not taken into consideration.
[0189] If, on the other hand, SF #m is not present within a range
of (X-1) ms going back from SF #n, the codebook size of SF #n is
determined without considering the codebook size of other UL
subframes. Note that although the second retention period (X)
described above is assumed as the retention period here, this is
not limiting. The above-described first retention period (Y) may be
taken into account.
[0190] FIG. 18 illustrates an example where the codebook size is
dynamically changed taking the A/N retention period into account.
In the case illustrated in FIG. 18, A/Ns in response to the DL
signals (for example, PDSCH) transmitted in SF #2 to SF #5 are
transmitted in SF #9, and A/Ns in response to the DL signals
transmitted in SF #11 to SF #14 are transmitted in SF #17.
[0191] Furthermore, in FIG. 18, the A/N transmission (codebook
size, etc.) in each UL subframe SF #9 and #17 is controlled based
on DAIs (Downlink Assignment Indicators (Indices)) included in DL
signals. As for the DAIs to be included in DL signals (for example,
DCI), a counter DAI (also referred to as "C-DAI," and so on), a
total DAI (also referred to as a "T-DAI" and so on), and others are
stipulated.
[0192] The counter DAI is information (count value) that is used to
count the DL signals that are scheduled (in FDD, this corresponds
to the number of CCs). The total DAI is information that indicates
the number of DL signals that are scheduled (in FDD, this
corresponds to the number of CCs). In the radio base station, the
counter DAI and the total DAI are included in each CC's downlink
control information and reported to the user terminal. Note that
the counter DAI and/or the total DIA can be specified using two
bits.
[0193] The user terminal can determine the number of scheduled DL
signals (codebook size) based on the reported total DAI and can
also determine the A/N for each DL signal based on the counter
DAI.
[0194] For example, in FIG. 18, the DCI of each DL signal
transmitted in SF #2 to SF #5 includes a different counter DAI
(here, 1 to 8) and a common total DAI (here, 8). Here, since no DL
signal with a counter DAI of 5 is received, the user terminal
determines that the user terminal has failed to receive the DL
signal with the counter DAI=5. The user terminal determines the A/N
and codebook size (here, 8) in each DL subframe based on the
counter DAI and the total DAI, and transmits multiple A/Ns in SF
#9.
[0195] Furthermore, in FIG. 18, the DCI of each DL signal
transmitted in SF #11 to SF #14 includes a different counter DAI
(here, 1 to 7) and a common total DAI (here, 7). Here, since no DL
signal with a counter DAI of 7 is received, the user terminal can
determine that the user terminal has failed to receive the DL
signal with the counter DAI=7. The user terminal determines the A/N
and codebook size (here, 7) of each DL subframe based on the
counter DAI and the total DAI, and transmits multiple A/Ns in SF
#17.
[0196] Thus, by determining the codebook size based on the total
DAI, it is possible to dynamically change the codebook size taking
into account the number of DL signals that are scheduled.
[0197] Furthermore, according to the present embodiment, when there
is a UL subframe (SF #m) within a range of (X-1) ms going backward
from SF #n where HARQ-ACK is transmitted, the codebook size of SF
#n is determined by additionally taking into account the codebook
size (for example, total DAI) of SF #m. For example, assume the
case where the HARQ-ACK codebook size in the UL subframe of SF #17
in FIG. 18 is determined.
[0198] In this case, the user terminal checks whether or not a UL
subframe is present in a range of a predetermined period (for
example, X-1 or less) backward from SF #17. For example, if X=9 is
configured, the user terminal checks whether or not a UL subframe
is present within a range of eight subframes backward from SF #17
(that is, in SFs #9 to #16). In FIG. 18, since there is a UL
subframe in SF #9, the user terminal determines the codebook size
in SF #17 taking into consideration the codebook size (for example,
the total DAI) in SF #9, and carries out A/N transmission
accordingly.
[0199] To be more specific, the user terminal combines the codebook
size in SF #9 (here, 8) and the codebook size (here, 7) of the A/Ns
transmitted in response to the DL signals of SFs #11 to #14, and
uses the resulting value (CBS=8+7) as the codebook size for SF #17.
Then, the user terminal feeds back A/Ns in response to the DL
signals of SFs #2 to #5 and A/Ns in response to the DL signals of
SFs #11 to #14 using this codebook size.
[0200] On the other hand, if, as illustrated in FIG. 19, there is
no UL subframe (SF #m) within a range of (X-1) ms going backward,
from SF #n in which HARQ-ACK is transmitted, the user terminal
determines the codebook size for SF #n without considering the
codebook size in SF #m. For example, assume the case where the
codebook size in the UL subframe of SF #22 in FIG. 19 is
determined. Note that, FIG. 19 is equivalent to a case where the
subframe of SF #17 in FIG. 18 is replaced by SF #22.
[0201] In this case, the user terminal checks whether or not a UL
subframe is present within a range of a predetermined period (for
example, X-1 or less) backward from SF #22. For example, when X=9
is configured, the user terminal checks whether or not a UL
subframe is present within a range of eight subframes backward from
SF #22 (that is, in SFs #14 to #21). In FIG. 19, the UL subframe
that is configured before SF #22 is SF #9 (which is beyond X-1 ms),
so that the user terminal determines the codebook size of SF #22
without considering the codebook size in SF #9, and performs A/N
transmission accordingly.
[0202] To be more specific, the user terminal determines the
codebook size (here, 7) of the A/Ns to transmit in response to the
DL signals of SFs #11 to #14 as the codebook size in SF #22. Then,
the user terminal feeds back A/Ns in response to the DL signals of
SFs #11 to #14 using this codebook size.
[0203] That is, in the case illustrated in FIG. 19, since the A/Ns
transmitted in SF #9 (the A/Ns transmitted in response to the DL
signals of SFs #2 to #5) are not retained in SF #22, the user
terminal performs A/N transmission without takes into consideration
the A/Ns in SF #9. In this way, the codebook size is changed
dynamically by taking into account the period for retaining A/Ns,
so that it is possible to prevent the opportunities for
transmitting A/Ns from reducing due to LBT results (LBT busy), and,
furthermore, prevent the overhead of the codebook size from
increasing.
[0204] HARQ-ACK transmission in LAA SCells is assumed to be
configured so that only A/Ns that have failed to be transmitted due
to "LBT busy" are transmitted at different timings than in existing
system (that is, an A/N, once transmitted successfully, is not
transmitted at a timing different from the existing one). By means
of this configuration, the dynamic codebook size, which has been
described above, can be suitably applied.
[0205] (Radio Communication System)
[0206] Now, the structure of the radio communication system
according to one embodiment of the present invention will be
described below. In this radio communication system, the radio
communication method according to one and/or a combination of the
above-described embodiments of the present invention is
employed.
[0207] FIG. 11 is a diagram to illustrate an example of a schematic
structure of a radio communication system according to one
embodiment of the present invention. A radio communication system 1
can adopt carrier aggregation (CA) and/or dual connectivity (DC) to
group a plurality of fundamental frequency blocks (component
carriers) into one, where the LTE system bandwidth constitutes 1
unit. Also, the radio communication system 1 has a radio base
station (for example, an LTE-U base station) that is capable of
using unlicensed bands.
[0208] Note that the radio communication system 1 may be referred
to as "SUPER 3G," "LTE-A" (LTE-Advanced), "IMT-Advanced," "4G" (4th
generation mobile communication system), "5G" (5th generation
mobile communication system), "FRA" (Future Radio Access) and so
on.
[0209] The radio communication system 1 illustrated in FIG. 11
includes a radio base station 11 that forms a macro cell C1, and
radio base stations 12 (12a to 12c) that form small cells C2, which
are placed within the macro cell C1 and which are narrower than the
macro cell C1. Also, user terminals 20 are placed in the macro cell
C1 and in each small cell C2. For example, a mode may be possible
in which the macro cell C1 is used in a licensed band and the small
cells C2 are used in unlicensed bands (LTE-U). Also, a mode may be
also possible in which part of the small cells is used in a
licensed band and the rest of the small cells are used in
unlicensed bands.
[0210] The user terminals 20 can connect with both the radio base
station 11 and the radio base stations 12. The user terminals 20
may use the macro cell C1 and the small cells C2, which use
different frequencies, at the same time, by means of CA or DC. For
example, it is possible to transmit assist information (for
example, the DL signal configuration) related to a radio base
station 12 (which is, for example, an LTE-U base station) that uses
an unlicensed band, from the radio base station 11 that uses a
licensed band to the user terminals 20. Furthermore, a structure
may be employed here in which, when CA is applied between a
licensed band and an unlicensed band, 1 radio base station (for
example, the radio base station 11) controls the scheduling of
licensed band cells and unlicensed band cells.
[0211] Note that it is equally possible to adopt a structure in
which a user terminal 20 connects with the radio base stations 12,
without connecting with the radio base station 11. For example, it
is possible to adopt a structure in which a radio base station 12
that uses an unlicensed band establishes a stand-alone connection
with a user terminal 20. In this case, the radio base station 12
controls the scheduling of unlicensed band cells.
[0212] Between the user terminals 20 and the radio base station 11,
communication can be carried out using a carrier of a relatively
low frequency band (for example, 2 GHz) and a narrow bandwidth
(referred to as, for example, an "existing carrier," a "legacy
carrier" and so on). Meanwhile, between the user terminals 20 and
the radio base stations 12, a carrier of a relatively high
frequency band (for example, 3.5 GHz, 5 GHz and so on) and a wide
bandwidth may be used, or the same carrier as that used in the
radio base station 11 may be used. Note that the structure of the
frequency band for use in each radio base station is by no means
limited to these.
[0213] A structure may be employed here in which wire connection
(for example, means in compliance with the CPRI (Common Public
Radio Interface) such as optical fiber, the X2 interface and so on)
or wireless connection is established between the radio base
station 11 and the radio base station 12 (or between two radio base
stations 12).
[0214] The radio base station 11 and the radio base stations 12 are
each connected with higher station apparatus 30, and are connected
with a core network 40 via the higher station apparatus 30. Note
that the higher station apparatus 30 may be, for example, access
gateway apparatus, a radio network controller (RNC), a mobility
management entity (MME) and so on, but is by no means limited to
these. Also, each radio base station 12 may be connected with the
higher station apparatus 30 via the radio base station 11.
[0215] Note that the radio base station 11 is a radio base station
having a relatively wide coverage, and may be referred to as a
"macro base station," a "central node," an "eNB" (eNodeB), a
"transmitting/receiving point" and so on. Also, the radio base
stations 12 are radio base stations having local coverages, and may
be referred to as "small base stations," "micro base stations,"
"pico base stations," "femto base stations," "HeNBs (Home
eNodeBs)," "RRHs (Remote Radio Heads)," "transmitting/receiving
points" and so on. Hereinafter the radio base stations 11 and 12
will be collectively referred to as "radio base stations 10,"
unless specified otherwise. Also, it is preferable to configure
radio base stations 10 that use the same unlicensed band on a
shared basis to be synchronized in time.
[0216] The user terminals 20 are terminals that support various
communication schemes such as LTE, LTE-A and so on, and may be
either mobile communication terminals or stationary communication
terminals.
[0217] In the radio communication system 1, as radio access
schemes, OFDMA (Orthogonal Frequency Division Multiple Access) is
applied to the downlink and SC-FDMA (Single-Carrier Frequency
Division Multiple Access) is applied to the uplink.
[0218] OFDMA is a multi-carrier communication scheme to perform
communication by dividing a frequency bandwidth into a plurality of
narrow frequency bandwidths (subcarriers) and mapping data to each
subcarrier. SC-FDMA is a single-carrier communication scheme to
mitigate interference between terminals by dividing the system
bandwidth into bands formed with one or continuous resource blocks
per terminal, and allowing a plurality of terminals to use mutually
different bands. Note that the uplink and downlink radio access
schemes are by no means limited to the combination of these.
[0219] In the radio communication system 1, a downlink shared
channel (PDSCH: Physical Downlink Shared CHannel), which is used by
each user terminal 20 on a shared basis, a broadcast channel (PBCH:
Physical Broadcast CHannel), downlink L1/L2 control channels and so
on are used as downlink channels. User data, higher layer control
information and SIBs (System Information Blocks) are communicated
in the PDSCH. Also, the MIB (Master Information Block) is
communicated in the PBCH.
[0220] The downlink L1/L2 control channels include a PDCCH
(Physical Downlink Control CHannel), an EPDCCH (Enhanced Physical
Downlink Control CHannel), a PCFICH (Physical Control Format
Indicator CHannel), a PHICH (Physical Hybrid-ARQ Indicator CHannel)
and so on. Downlink control information (DCI), including PDSCH and
PUSCH scheduling information, is communicated by the PDCCH. The
number of OFDM symbols to use for the PDCCH is communicated by the
PCFICH. HARQ delivery acknowledgement signals (ACK/NACK) in
response to the PUSCH are communicated by the PHICH. The EPDCCH is
frequency-division-multiplexed with the PDSCH and used to
communicate DCI and so on, like the PDCCH.
[0221] In the radio communication system 1, an uplink shared
channel (PUSCH: Physical Uplink Shared CHannel), which is used by
each user terminal 20 on a shared basis, an uplink control channel
(PUCCH: Physical Uplink Control CHannel), a random access channel
(PRACH: Physical Random Access CHannel) and so on are used as
uplink channels. The PUSCH may be referred to as an "uplink data
channel." User data and higher layer control information are
communicated by the PUSCH. Also, downlink radio quality information
(CQI: Channel Quality Indicator), delivery acknowledgment
information (ACK/NACK) and so on are communicated by the PUCCH. By
means of the PRACH, random access preambles for establishing
connections with cells are communicated.
[0222] In the radio communication systems 1, cell-specific
reference signals (CRSs), channel state information reference
signals (CSI-RSs), demodulation reference signal (DMRSs) and so on
are communicated as downlink reference signals. Also, in the radio
communication system 1, the measurement reference signal (SRS:
Sounding Reference Signal), the demodulation reference signal
(DMRS) and so on are communicated as uplink reference signals. Note
that the DMRS may be referred to as a "user terminal-specific
reference signal (UE-specific Reference Signal)." Also, the
reference signals to be communicated are by no means limited to
these.
[0223] (Radio Base Station)
[0224] FIG. 12 is a diagram to illustrate an example of an overall
structure of a radio base station according to one embodiment of
the present invention. A radio base station 10 has a plurality of
transmitting/receiving antennas 101, amplifying sections 102,
transmitting/receiving sections 103, a baseband signal processing
section 104, a call processing section 105 and a communication path
interface 106. Note that one or more transmitting/receiving
antennas 101, amplifying sections 102 and transmitting/receiving
sections 103 may be provided.
[0225] User data to be transmitted from the radio base station 10
to a user terminal 20 on the downlink is input from the higher
station apparatus 30 to the baseband signal processing section 104,
via the communication path interface 106.
[0226] In the baseband signal processing section 104, the user data
is subjected to transmission processes, including a PDCP (Packet
Data Convergence Protocol) layer process, division and coupling of
the user data, RLC (Radio Link Control) layer transmission
processes such as RLC retransmission control, MAC (Medium Access
Control) retransmission control (for example, an HARQ (Hybrid
Automatic Repeat reQuest) transmission process), scheduling,
transport format selection, channel coding, an inverse fast Fourier
transform (IFFT) process and a precoding process, and the result is
forwarded to each transmitting/receiving sections 103. Furthermore,
downlink control signals are also subjected to transmission
processes such as channel coding and an inverse fast Fourier
transform, and forwarded to each transmitting/receiving section
103.
[0227] Baseband signals that are precoded and output from the
baseband signal processing section 104 on a per antenna basis are
converted into a radio frequency band in the transmitting/receiving
sections 103, and then transmitted. The radio frequency signals
having been subjected to frequency conversion in the
transmitting/receiving sections 103 are amplified in the amplifying
sections 102, and transmitted from the transmitting/receiving
antennas 101.
[0228] The transmitting/receiving sections 103 are capable of
transmitting/receiving UL/DL signals in unlicensed bands. Note that
the transmitting/receiving sections 103 may be capable of
transmitting/receiving UL/DL signals in licensed bands as well. The
transmitting/receiving sections 103 can be constituted by
transmitters/receivers, transmitting/receiving circuits or
transmitting/receiving apparatus that can be described based on
general understanding of the technical field to which the present
invention pertains. Note that a transmitting/receiving section 103
may be structured as a transmitting/receiving section in one
entity, or may be constituted by a transmitting section and a
receiving section.
[0229] Meanwhile, as for uplink signals, radio frequency signals
that are received in the transmitting/receiving antennas 101 are
each amplified in the amplifying sections 102. The
transmitting/receiving sections 103 receive the uplink signals
amplified in the amplifying sections 102. The received signals are
converted into the baseband signal through frequency conversion in
the transmitting/receiving sections 103 and output to the baseband
signal processing section 104.
[0230] In the baseband signal processing section 104, user data
that is included in the uplink signals that are input is subjected
to a fast Fourier transform (FFT) process, an inverse discrete
Fourier transform (IDFT) process, error correction decoding, a MAC
retransmission control receiving process, and RLC layer and PDCP
layer receiving processes, and forwarded to the higher station
apparatus 30 via the communication path interface 106. The call
processing section 105 performs call processing (such as setting up
and releasing communication channels), manages the state of the
radio base stations 10 and manages the radio resources.
[0231] The communication path interface section 106 transmits and
receives signals to and from the higher station apparatus 30 via a
predetermined interface. Also, the communication path interface 106
may transmit and receive signals (backhaul signaling) with other
radio base stations 10 via an inter-base station interface (which
is, for example, optical fiber that is in compliance with the CPRI
(Common Public Radio Interface), the X2 interface, etc.).
[0232] Note that the transmitting/receiving sections 103 transmit
downlink control information (DCI) and/or higher layer signaling
(for example, RRC signaling), which include PUCCH cell
configuration information, information as to whether or not
simultaneous PUCCH and PUSCH transmission is possible, information
about UCI transmission modes, and information about UCI retention
periods, and so on, to the user terminal 20 in licensed CCs and/or
unlicensed CCs. In addition, the transmitting/receiving sections
103 can receive the PUSCH from the user terminal 20 at least in
unlicensed CCs.
[0233] FIG. 13 is a diagram to illustrate an example of a
functional structure of a radio base station according to one
embodiment of the present invention. Note that, although FIG. 10
primarily illustrates functional blocks that pertain to
characteristic parts of the present embodiment, the radio base
station 10 has other functional blocks that are necessary for radio
communication as well.
[0234] The baseband signal processing section 104 has a control
section (scheduler) 301, a transmission signal generation section
302, a mapping section 303, a received signal processing section
304 and a measurement section 305. Note that these configurations
have only to be included in the radio base station 10, and some or
all of these configurations may not be included in the baseband
signal processing section 104.
[0235] The control section (scheduler) 301 controls the whole of
the radio base station 10. Note that, when a licensed band and an
unlicensed band are scheduled with 1 control section (scheduler)
301, the control section 301 controls communication in licensed
band cells and unlicensed band cells. For the control section 301,
a controller, a control circuit or control apparatus that can be
described based on common understanding of the technical field to
which the present invention pertains can be used.
[0236] The control section 301, for example, controls the
generation of signals in the transmission signal generation section
302, the allocation of signals by the mapping section 303, and so
on. Furthermore, the control section 301 controls the signal
receiving processes in the received signal processing section 304,
the measurements of signals in the measurement section 305, and so
on.
[0237] The control section 301 controls the scheduling (for
example, resource allocation) of downlink data signals that are
transmitted in the PDSCH and downlink control signals that are
communicated in the PDCCH and/or the EPDCCH. Also, the control
section 301 controls the scheduling of downlink reference signals
such as synchronization signals (the PSS (Primary Synchronization
Signal) and the SSS (Secondary Synchronization Signal)), the CRS,
the CSI-RS, the DM-RS and so on.
[0238] Also, the control section 301 controls the scheduling of
uplink data signals transmitted in the PUSCH, uplink control
signals transmitted in the PUCCH and/or the PUSCH (for example,
delivery acknowledgement signals (HARQ-ACKs)), random access
preambles transmitted in the PRACH, uplink reference signals and so
on.
[0239] The control section 301 may control the transmission signal
generation section 302 and the mapping section 303 to transmit
downlink signals (for example, PDCCH/EPDCCH) in carriers (for
example, unlicensed CCs) where listening is performed before
downlink transmission according to the LBT result obtained in the
measurement section 305.
[0240] The control section 301 may exert control so that UE
capability information as to whether or not PF 4/5 are supported in
at least one of the LBT carriers is obtained from the received
signal processing section 304, the PUCCH cell of LAA SCells is
determined based on this capability information, and PUCCH cell
configuration information pertaining to this cell is transmitted to
the user terminal 20.
[0241] The control section 301 may exert control so that
information as to whether or not simultaneous transmission of PUCCH
and PUSCH is possible, information about UCI transmission modes,
information about UCI retention periods and so on are transmitted
to the user terminal 20.
[0242] Furthermore, the control section 301 may determine in which
cell the user terminal transmits UCI based on the various pieces of
information transmitted to the user terminal 20, and perform the
receiving process and scheduling accordingly.
[0243] Furthermore, the control section 301 may control (determine)
the codebook size to use to transmit an A/N based on the time the
A/N (retransmission control information) is retained in the user
terminal 20 (for example, at least one of the first retention time
(Y) and the second retention time (X)). Furthermore, the control
section 301 may control the codebook size based on the number of
CCs, in addition to the time the A/N is retained.
[0244] The codebook size may be a fixed size that is uniquely
determined in each TTI (also referred to as "fixed codebook size,"
as illustrated in FIG. 17), or may be a size that is dynamically
changed (also referred to as "dynamic codebook size," as
illustrated in FIGS. 18 and 19). The fixed codebook size may be
equal to the maximum number of A/Ns that may be transmitted in each
TTI.
[0245] The transmission signal generation section 302 generates
downlink signals (downlink control signals, downlink data signals,
downlink reference signals and so on) based on commands from the
control section 301, and outputs these signals to the mapping
section 303. The transmission signal generation section 302 can be
constituted by a signal generator, a signal generating circuit or
signal generating apparatus that can be described based on general
understanding of the technical field to which the present invention
pertains.
[0246] For example, the transmission signal generation section 302
generates DL assignments, which report downlink signal allocation
information, and UL grants, which report uplink signal allocation
information, based on commands from the control section 301. Also,
the downlink data signals are subjected to the coding process, the
modulation process and so on, by using coding rates and modulation
schemes that are determined based on, for example, channel state
information (CSI) from each user terminal 20.
[0247] The mapping section 303 maps the downlink signals generated
in the transmission signal generation section 302 to predetermined
radio resources based on commands from the control section 301, and
outputs these to the transmitting/receiving sections 103. The
mapping section 303 can be constituted by a mapper, a mapping
circuit or mapping apparatus that can be described based on general
understanding of the technical field to which the present invention
pertains.
[0248] The received signal processing section 304 performs
receiving processes (for example, demapping, demodulation, decoding
and so on) of received signals that are input from the
transmitting/receiving sections 103. Here, the received signals
include, for example, uplink signals transmitted from the user
terminals 20 (uplink control signals, uplink data signals, uplink
reference signals and so on). For the received signal processing
section 304, a signal processor, a signal processing circuit or
signal processing apparatus that can be described based on general
understanding of the technical field to which the present invention
pertains can be used.
[0249] The received signal processing section 304 outputs the
decoded information acquired through the receiving processes to the
control section 301. For example, when a PUCCH to contain an
HARQ-ACK is received, the received signal processing section 304
outputs this HARQ-ACK to the control section 301. Also, the
received signal processing section 304 outputs the received
signals, the signals after the receiving processes and so on, to
the measurement section 305.
[0250] The measurement section 305 conducts measurements with
respect to the received signals. The measurement section 305 can be
constituted by a measurer, a measurement circuit or measurement
apparatus that can be described based on general understanding of
the technical field to which the present invention pertains.
[0251] The measurement section 305 executes LBT in a carrier where
LBT is configured (for example, an unlicensed band) based on
commands from the control section 301, and outputs the results of
LBT (for example, judgments as to whether the channel state is free
or busy) to the control section 301.
[0252] Also, the measurement section 305 may measure, for example,
the received power (for example, RSRP (Reference Signal Received
Power)), the received signal strength (for example, RSSI (Received
Signal Strength Indicator)), the received quality (for example,
RSRQ (Reference Signal Received Quality)) and the channel states of
the received signals. The measurement results may be output to the
control section 301.
[0253] (User Terminal)
[0254] FIG. 14 is a diagram to illustrate an example of an overall
structure of a user terminal according to one embodiment of the
present invention. A user terminal 20 has a plurality of
transmitting/receiving antennas 201, amplifying sections 202,
transmitting/receiving sections 203, a baseband signal processing
section 204 and an application section 205. Note that one or more
transmitting/receiving antennas 201, amplifying sections 202 and
transmitting/receiving sections 203 may be provided.
[0255] Radio frequency signals that are received in the
transmitting/receiving antennas 201 are amplified in the amplifying
sections 202. The transmitting/receiving sections 203 receive the
downlink signals amplified in the amplifying sections 202. The
received signals are subjected to frequency conversion and
converted into the baseband signal in the transmitting/receiving
sections 203, and output to the baseband signal processing section
204. The transmitting/receiving sections 203 are capable of
transmitting/receiving UL/DL signals in unlicensed bands. Note that
the transmitting/receiving sections 203 may be capable of
transmitting/receiving UL/DL signals in licensed bands as well.
[0256] A transmitting/receiving section 203 can be constituted by a
transmitters/receiver, a transmitting/receiving circuit or
transmitting/receiving apparatus that can be described based on
general understanding of the technical field to which the present
invention pertains. Note that a transmitting/receiving section 203
may be structured as a transmitting/receiving section in one
entity, or may be constituted by a transmitting section and a
receiving section.
[0257] In the baseband signal processing section 204, the baseband
signal that is input is subjected to an FFT process, error
correction decoding, a retransmission control receiving process,
and so on. Downlink user data is forwarded to the application
section 205. The application section 205 performs processes related
to higher layers above the physical layer and the MAC layer, and so
on. Furthermore, in the downlink data, broadcast information is
also forwarded to the application section 205.
[0258] Meanwhile, uplink user data is input from the application
section 205 to the baseband signal processing section 204. The
baseband signal processing section 204 performs a retransmission
control transmission process (for example, an HARQ transmission
process), channel coding, precoding, a discrete Fourier transform
(DFT) process, an IFFT process and so on, and the result is
forwarded to the transmitting/receiving section 203. Baseband
signals that are output from the baseband signal processing section
204 are converted into a radio frequency band in the
transmitting/receiving sections 203 and transmitted. The radio
frequency signals that are subjected to frequency conversion in the
transmitting/receiving sections 203 are amplified in the amplifying
sections 202, and transmitted from the transmitting/receiving
antennas 201.
[0259] Note that the transmitting/receiving sections 203 receive
downlink control information (DCI) including PUCCH cell
configuration information, information as to whether or not
simultaneous PUCCH and PUSCH transmission is possible, information
about UCI transmission modes, information about UCI retention
periods, etc. and/or higher layer signaling (for example, RRC
signaling), from the radio base station 10, in licensed CCs and/or
unlicensed CCs. In addition, the transmitting/receiving sections
203 can transmit the PUSCH to the radio base station 10 at least in
unlicensed CCs.
[0260] FIG. 15 is a diagram to illustrate an example of a
functional structure of a user terminal according to one embodiment
of the present invention.
[0261] Note that, although FIG. 15 primarily illustrates functional
blocks that pertain to characteristic parts of the present
embodiment, the user terminal 20 has other functional blocks that
are necessary for radio communication as well.
[0262] The baseband signal processing section 204 provided in the
user terminal 20 at least has a control section 401, a transmission
signal generation section 402, a mapping section 403, a received
signal processing section 404 and a measurement section 405. Note
that these configurations have only to be included in the user
terminal 20, and some or all of these configurations may not be
included in the baseband signal processing section 204.
[0263] The control section 401 controls the whole of the user
terminal 20. For the control section 401, a controller, a control
circuit or control apparatus that can be described based on general
understanding of the technical field to which the present invention
pertains can be used.
[0264] The control section 401, for example, controls the
generation of signals in the transmission signal generation section
402, the allocation of signals by the mapping section 403, and so
on. Furthermore, the control section 401 controls the signal
receiving processes in the received signal processing section 404,
the measurements of signals in the measurement section 405, and so
on.
[0265] The control section 401 acquires the downlink control
signals (signals transmitted in the PDCCH/EPDCCH) and downlink data
signals (signals transmitted in the PDSCH) transmitted from the
radio base station 10, via the received signal processing section
404. The control section 401 controls the generation of uplink
control signals (for example, delivery acknowledgement signals
(HARQ-ACKs) and so on) and uplink data signals based on the
downlink control signals, the results of deciding whether or not re
transmission control is necessary for the downlink data signals,
and so on.
[0266] The control section 401 may control the transmission signal
generation section 402 and the mapping section 403 to transmit
uplink signals (for example, PUCCH, PUSCH, etc.) in carriers (LBT
carriers) where listening is performed before uplink transmission,
according to LBT results acquired in the measurement section
405.
[0267] The control section 401 determines whether or not PUCCH
transmission is possible in LAA SCells, based on information (PUCCH
cell configuration information) as to whether or not at least one
of the LBT carriers is a cell where PUCCH is transmitted ("PUCCH
cell," "PUCCH SCell," etc.), acquired from the received signal
processing section 404, and controls the transmission of UCI in
each LAA SCell.
[0268] The control section 401 can obtain information as to whether
simultaneous transmission of an uplink control channel (for
example, PUCCH) and an uplink shared channel (for example, PUSCH)
is possible, from the received signal processing section 404.
Furthermore, if the control section 401 determines that PUCCH
transmission is possible in one of the LAA SCells based on the
PUCCH cell configuration information, the control section 401 can
further control the transmission of UCI in each LAA SCell based on
this information as to whether or not simultaneous transmission is
possible.
[0269] The control section 401 may obtain information related to
UCI transmission modes, which specify in which carriers various
UCIs pertaining to non-LBT carriers and LBT carriers are
transmitted, from the received signal processing section 404.
Furthermore, when the control section 401 determines that PUCCH
transmission is not possible in any of the LAA SCells, based on the
PUCCH cell configuration information, the control section 401 can
further control the transmission of UCI in each LAA SCell based on
this UCI transmission mode-related information.
[0270] The control section 401 may exert control so that UE
capability information as to whether PF 4/5 are supported in at
least one of the LBT carriers is transmitted.
[0271] The control section 401 may exert control so that various
UCIs are retained for a predetermined period of time (for example,
for a first retention period, a second retention period, etc.), and
a plurality of UCIs (for example, all UCIs of all LAA SCells) that
are retained for LBT carriers are transmitted simultaneously
(together) in at least one LAA SCell.
[0272] The control section 401 may control the codebook size to use
to transmit an A/N based on the time the A/N (retransmission
control information) is retained (for example, at least one of the
first retention time (Y) and the second retention time (X)). Also,
the control section 401 may control (determines) the codebook size
based on the number of CCs, in addition to the retention time of
the A/N.
[0273] The codebook size may be a fixed size that is uniquely
determined in each TTI (also referred to as "fixed codebook size,"
as illustrated in FIG. 17), or may be a size that is changed
dynamically (also referred to as "dynamic codebook size," as
illustrated in FIG. 18 and FIG. 19). The fixed codebook size may be
equal to the maximum number of A/Ns that can be transmitted in each
TTI.
[0274] The transmission signal generation section 402 generates
uplink signals (uplink control signals, uplink data signals, uplink
reference signals and so on) based on commands from the control
section 401, and outputs these signals to the mapping section 403.
The transmission signal generation section 402 can be constituted
by a signal generator, a signal generating circuit or signal
generating apparatus that can be described based on general
understanding of the technical field to which the present invention
pertains.
[0275] For example, the transmission signal generating section 402
generates uplink control signals such as delivery acknowledgement
signals (HARQ-ACKs), channel state information (CSI) and so on,
based on commands from the control section 401. Also, the
transmission signal generation section 402 generates uplink data
signals based on commands from the control section 401. For
example, when a UL grant is included in a downlink control signal
that is reported from the radio base station 10, the control
section 401 commands the transmission signal generation section 402
to generate an uplink data signal.
[0276] The mapping section 403 maps the uplink signals generated in
the transmission signal generation section 402 to radio resources
based on commands from the control section 401, and outputs the
result to the transmitting/receiving sections 203. The mapping
section 403 can be constituted by a mapper, a mapping circuit or
mapping apparatus that can be described based on general
understanding of the technical field to which the present invention
pertains.
[0277] The received signal processing section 404 performs
receiving processes (for example, demapping, demodulation, decoding
and so on) of received signals that are input from the
transmitting/receiving sections 203. Here, the received signals
include, for example, downlink signals (downlink control signals,
downlink data signals, downlink reference signals and so on) that
are transmitted from the radio base station 10. The received signal
processing section 404 can be constituted by a signal processor, a
signal processing circuit or signal processing apparatus that can
be described based on general understanding of the technical field
to which the present invention pertains. Also, the received signal
processing section 404 can constitute the receiving section
according to the present invention.
[0278] The received signal processing section 404 outputs the
decoded information, acquired through the receiving processes, to
the control section 401. The received signal processing section 404
outputs, for example, broadcast information, system information,
RRC signaling, DCI and so on, to the control section 401. Also, the
received signal processing section 404 outputs the received
signals, the signals after the receiving processes and so on, to
the measurement section 405.
[0279] The measurement section 405 conducts measurements with
respect to the received signals. The measurement section 405 can be
constituted by a measurer, a measurement circuit or measurement
apparatus that can be described based on general understanding of
the technical field to which the present invention pertains.
[0280] The measurement section 405 executes LBT in carriers where
LBT is configured, based on commands from the control section 401.
The measurement section 405 may output the results of LBT (for
example, judgments as to whether the channel state is free or busy)
to the control section 401.
[0281] Also, the measurement section 405 may measure the received
power (for example, RSRP), the received signal strength (RSSI), the
received quality (for example, RSRQ) and the channel states and so
on of the received signals. The measurement results may be output
to the control section 401.
[0282] (Hardware Structure)
[0283] Note that the block diagrams that have been used to describe
the above embodiments indicate blocks in functional units. These
functional blocks (components) may be implemented in arbitrary
combinations of hardware and/or software. Also, the means for
implementing each functional block is not particularly limited.
That is, each functional block may be implemented with 1 piece of
physically-integrated apparatus, or may be implemented by
connecting 2 physically-separate pieces of apparatus via radio or
wire and by using these multiple pieces of apparatus.
[0284] For example, the radio base station, user terminals and so
on according to embodiments of the present invention may function
as a computer that executes the processes of the radio
communication method of the present invention. FIG. 16 is a diagram
to illustrate an example hardware structure of a radio base station
and a user terminal according to one embodiment of the present
invention. Physically, the above-described radio base stations 10
and user terminals 20 may be formed as a computer apparatus that
includes a processor 1001, a memory 1002, a storage 1003,
communication apparatus 1004, input apparatus 1005, output
apparatus 1006 and a bus 1007.
[0285] Note that, in the following description, the word
"apparatus" may be replaced by "circuit," "device," "unit" and so
on. Note that the hardware structure of a radio base station 10 and
a user terminal 20 may be designed to include one or more of each
apparatus illustrated in the drawings, or may be designed not to
include part of the apparatus.
[0286] For example, although only one processor 1001 is
illustrated, a plurality of processors may be provided.
Furthermore, processes may be implemented with one processor, or
processes may be implemented in sequence, or in different manners,
on one or more processors.
[0287] Each function of the radio base station 10 and the user
terminal 20 is implemented by reading predetermined software
(program) on hardware such as the processor 1001 and the memory
1002, and by controlling the calculations in the processor 1001,
the communication in the communication apparatus 1004, and the
reading and/or writing of data in the memory 1002 and the storage
1003.
[0288] The processor 1001 may control the whole computer by, for
example, running an operating system. The processor 1001 may be
configured with a central processing unit (CPU), which includes
interfaces with peripheral apparatus, control apparatus, computing
apparatus, a register and so on. For example, the above-described
baseband signal processing section 104 (204), call processing
section 105 and so on may be implemented by the processor 1001.
[0289] Furthermore, the processor 1001 reads programs (program
codes), software modules or data, from the storage 1003 and/or the
communication apparatus 1004, into the memory 1002, and executes
various processes according to these. As for the programs, programs
to allow computers to execute at least part of the operations of
the above-described embodiments may be used. For example, the
control section 401 of the user terminals 20 may be implemented by
control programs that are stored in the memory 1002 and that
operate on the processor 1001, and other functional blocks may be
implemented likewise.
[0290] The memory 1002 is a computer-readable recording medium, and
may be constituted by, for example, at least one of a ROM (Read
Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM
(Electrically EPROM), a RAM (Random Access Memory) and/or other
appropriate storage media. The memory 1002 may be referred to as a
"register," a "cache," a "main memory" (primary storage apparatus)
and so on. The memory 1002 can store executable programs (program
codes), software modules and/and so on for implementing the radio
communication methods according to embodiments of the present
invention.
[0291] The storage 1003 is a computer-readable recording medium,
and may be constituted by, for example, at least one of a flexible
disk, a floppy (registered trademark) disk, a magneto-optical disk
(for example, a compact disc (CD-ROM (Compact Disc ROM) and so on),
a digital versatile disc, a Blu-ray (registered trademark) disk), a
removable disk, a hard disk drive, a smart card, a flash memory
device (for example, a card, a stick, a key drive, etc.), a
magnetic stripe, a database, a server, and/or other appropriate
storage media. The storage 1003 may be referred to as "secondary
storage apparatus."
[0292] The communication apparatus 1004 is hardware
(transmitting/receiving device) for allowing inter-computer
communication by using wired and/or wireless networks, and may be
referred to as, for example, a "network device," a "network
controller," a "network card," a "communication module" and so on.
For example, the above-described transmitting/receiving antennas
101 (201), amplifying sections 102 (202), transmitting/receiving
sections 103 (203), communication path interface 106 and so on may
be implemented by the communication apparatus 1004.
[0293] The input apparatus 1005 is an input device for receiving
input from the outside (for example, a keyboard, a mouse, etc.).
The output apparatus 1006 is an output device for sending output to
the outside (for example, a display, a speaker, etc.). Note that
the input apparatus 1005 and the output apparatus 1006 may be
provided in an integrated structure (for example, a touch
panel).
[0294] Furthermore, these types of apparatus, including the
processor 1001, the memory 1002 and others, are connected by a bus
1007 for communicating information. The bus 1007 may be formed with
a single bus, or may be formed with buses that vary between pieces
of apparatus.
[0295] Also, the radio base station 10 and the user terminal 20 may
be structured to include hardware such as a microprocessor, a
digital signal processor (DSP), an ASIC (Application-Specific
Integrated Circuit), a PLD (Programmable Logic Device), an FPGA
(Field Programmable Gate Array) and so on, and part or all of the
functional blocks may be implemented by the hardware. For example,
the processor 1001 may be implemented with at least one of these
pieces of hardware.
[0296] (Variations)
[0297] Note that the terminology used in this specification and the
terminology that is needed to understand this specification may be
replaced by other terms that convey the same or similar meanings.
For example, "channels" and/or "symbols" may be replaced by
"signals (or "signaling")." Also, "signals" may be "messages." A
reference signal may be abbreviated as an "RS," and may be referred
to as a "pilot," depending on which standard applies. Furthermore,
a "component carrier" (CC) may be referred to as a "cell," a
"frequency carrier," a "carrier frequency" and so on.
[0298] Furthermore, a radio frame may be comprised of one or more
periods (frames) in the time domain. Each of one or more periods
(frames) constituting a radio frame may be referred to as a
"subframe." Furthermore, a subframe may be comprised of one or more
slots in the time domain. Furthermore, a slot may be comprised of 1
or multiple symbols (OFDM symbols, SC-FDMA symbols, etc.) in the
time domain.
[0299] A radio frame, a subframe, a slot and a symbol all represent
the time unit in signal communication. A radio frames, a subframe,
a slot and a symbol may be each called by other applicable names.
For example, one subframe may be referred to as a "transmission
time interval" (TTI), or a plurality of consecutive subframes may
be referred to as a "TTI," or one slot may be referred to as a
"TTI." That is, a subframe and a TTI may be a subframe (1 ms) in
existing LTE, may be a shorter period than 1 ms (for example, one
to thirteen symbols), or may be a longer period of time than 1
ms.
[0300] Here, a TTI refers to the minimum time unit of scheduling in
radio communication, for example. For example, in LTE systems, a
radio base station schedules the allocation of radio resources
(such as the frequency bandwidth and transmission power that can be
used by each user terminal) for each user terminal in TTI units.
Note that the definition of TTIs is not limited to this. The TTI
may be the transmission time unit of channel-encoded data packets
(transport blocks), or may be the unit of processing in scheduling,
link adaptation and so on.
[0301] A TTI having a time duration of 1 ms may be referred to as a
"normal TTI" (TTI in LTE Rel. 8 to 12), a "long TTI," a "normal
subframe," a "long subframe," and so on. A TTI that is shorter than
a normal TTI may be referred to as a "shortened TTI," a "short
TTI," a "shortened subframe," a "short subframe," and so on.
[0302] A resource block (RB) is the unit of resource allocation in
the time domain and the frequency domain, and may include one or a
plurality of consecutive subcarriers in the frequency domain. Also,
an RB may include one or more symbols in the time domain, and may
be one slot, one subframe or one TTI in length. One TTI and one
subframe each may be comprised of one or more resource blocks. Note
that an RB may be referred to as a "physical resource block" (PRB:
Physical RB), a "PRB pair," an "RB pair," and so on.
[0303] Furthermore, a resource block may be comprised of one or
more resource elements (REs). For example, one RE may be a radio
resource field of one subcarrier and one symbol.
[0304] Note that the above-described structures of radio frames,
subframes, slots, symbols and so on are merely examples. For
example, configurations such as the number of subframes included in
a radio frame, the number of slots included in a subframe, the
number of symbols and RBs included in a slot, the number of
subcarriers included in an RB, the number of symbols in a TTI, the
symbol duration and cyclic prefix (CP) length can be variously
changed.
[0305] Also, the information and parameters described in this
specification may be represented in absolute values or in relative
values with respect to predetermined values, or may be represented
in other information formats. For example, radio resources may be
specified by predetermined indices.
[0306] The information, signals and/or others described in this
specification may be represented by using a variety of different
technologies. For example, data, instructions, commands,
information, signals, bits, symbols and chips, all of which may be
referenced throughout the herein-contained description, may be
represented by voltages, currents, electromagnetic waves, magnetic
fields or particles, optical fields or photons, or any combination
of these.
[0307] Also, information, signals and so on can be output from
higher layers to lower layers and/or from lower layers to higher
layers. Information, signals and so on may be input and output via
a plurality of network nodes.
[0308] The information, signals and so on that are input may be
transmitted to other pieces of apparatus. The information, signals
and so on to be input and/or output can be overwritten, updated or
appended. The information, signals and so on that are output may be
deleted. The information, signals and so on that are input may be
transmitted to other pieces of apparatus.
[0309] Reporting of information is by no means limited to the
examples/embodiments described in this specification, and other
methods may be used as well. For example, reporting of information
may be implemented by using physical layer signaling (for example,
DCI (Downlink Control Information) and UCI (Uplink Control
Information)), higher layer signaling (for example, RRC (Radio
Resource Control) signaling, broadcast information (the MIB (Master
Information Blocks) and SIBs (System Information Blocks) and so on)
and MAC (Medium Access Control) signaling, other signals or
combinations of these.
[0310] Also, RRC signaling may be referred to as "RRC messages,"
and can be, for example, an RRC connection setup message, RRC
connection reconfiguration message, and so on. Also, MAC signaling
may be reported using, for example, MAC control elements (MAC CEs
(Control Elements)).
[0311] Also, predetermined information (for example, reporting of
information to the effect that "X holds") does not necessarily have
to be reported explicitly, and can be reported in an implicit
manner (by, for example, not reporting this piece of
information).
[0312] Decisions may be made in values represented by one bit (0 or
1), may be made in Boolean values that represent true or false, or
may be made by comparing numerical values (for example, comparison
against a predetermined value).
[0313] Software, whether referred to as "software," "firmware,"
"middleware," "microcode" or "hardware description language," or
called by other names, should be interpreted broadly, to mean
instructions, instruction sets, code, code segments, program codes,
programs, subprograms, software modules, applications, software
applications, software packages, routines, subroutines, objects,
executable files, execution threads, procedures, functions and so
on.
[0314] Also, software, commands, information and so on may be
transmitted and received via communication media. For example, when
software is transmitted from a website, a server or other remote
sources by using wired technologies (coaxial cables, optical fiber
cables, twisted-pair cables, digital subscriber lines (DSL) and so
on) and/or wireless technologies (infrared radiation and
microwaves), these wired technologies and/or wireless technologies
are also included in the definition of communication media.
[0315] The terms "system" and "network" as used herein are used
interchangeably.
[0316] As used herein, the terms "base station (BS)," "radio base
station," "eNB," "cell," "sector," "cell group," "carrier," and
"component carrier" may be used interchangeably. A base station may
be referred to as a "fixed station," "NodeB," "eNodeB (eNB),"
"access point," "transmission point," "receiving point," "femto
cell," "small cell" and so on.
[0317] A base station can accommodate one or more (for example,
three) cells (also referred to as "sectors"). When a base station
accommodates a plurality of cells, the entire coverage area of the
base station can be partitioned into multiple smaller areas, and
each smaller area can provide communication services through base
station subsystems (for example, indoor small base stations (RRHs:
Remote Radio Heads)). The term "cell" or "sector" refers to part or
all of the coverage area of a base station and/or a base station
subsystem that provides communication services within this
coverage.
[0318] As used herein, the terms "mobile station (MS)" "user
terminal," "user equipment (UE)" and "terminal" may be used
interchangeably. A base station may be referred to as a "fixed
station," "NodeB," "eNodeB (eNB)," "access point," "transmission
point," "receiving point," "femto cell," "small cell" and so
on.
[0319] A mobile station may be referred to, by a person skilled in
the art, as a "subscriber station," "mobile unit," "subscriber
unit," "wireless unit," "remote unit," "mobile device," "wireless
device," "wireless communication device," "remote device," "mobile
subscriber station," "access terminal," "mobile terminal,"
"wireless terminal," "remote terminal," "handset," "user agent,"
"mobile client," "client" or some other suitable terms.
[0320] Furthermore, the radio base stations in this specification
may be interpreted as user terminals. For example, each
aspect/embodiment of the present invention may be applied to a
configuration in which communication between a radio base station
and a user terminal is replaced with communication among a
plurality of user terminals (D2D: Device-to-Device). In this case,
user terminals 20 may have the functions of the radio base stations
10 described above. In addition, wording such as "uplink" and
"downlink" may be interpreted as "side." For example, an uplink
channel may be interpreted as a side channel.
[0321] Likewise, the user terminals in this specification may be
interpreted as radio base stations. In this case, the radio base
stations 10 may have the functions of the user terminals 20
described above.
[0322] Certain actions which have been described in this
specification to be performed by base station may, in some cases,
be performed by upper nodes.
[0323] In a network comprised of one or more network nodes with
base stations, it is clear that various operations that are
performed to communicate with terminals can be performed by base
stations, one or more network nodes (for example, MMEs (Mobility
Management Entities), S-GW (Serving-Gateways), and so on may be
possible, but these are not limiting) other than base stations, or
combinations of these.
[0324] The examples/embodiments illustrated in this specification
may be used individually or in combinations, which may be switched
depending on the mode of implementation. The order of processes,
sequences, flowcharts and so on that have been used to describe the
examples/embodiments herein may be re-ordered as long as
inconsistencies do not arise. For example, although various methods
have been illustrated in this specification with various components
of steps in exemplary orders, the specific orders that are
illustrated herein are by no means limiting.
[0325] The examples/embodiments illustrated in this specification
may be applied to LTE (Long Term Evolution), LTE-A (LTE-Advanced),
LTE-B (LTE-Beyond), SUPER 3G, IMT-Advanced, 4G (4th generation
mobile communication system), 5G (5th generation mobile
communication system), FRA (Future Radio Access), New-RAT (Radio
Access Technology), GSM (registered trademark) (Global System for
Mobile communications), CDMA 2000, UMB (Ultra Mobile Broadband),
IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX
(registered trademark)), IEEE 802.20, UWB (Ultra-WideBand),
Bluetooth (registered trademark), systems that use other adequate
radio communication methods and/or next-generation systems that are
enhanced based on these.
[0326] The phrase "based on" as used in this specification does not
mean "based only on," unless otherwise specified. In other words,
the phrase "based on" means both "based only on" and "based at
least on."
[0327] Reference to elements with designations such as "first,"
"second" and so on as used herein does not generally limit the
number/quantity or order of these elements. These designations are
used only for convenience, as a method for distinguishing between
two or more elements. Thus, reference to the first and second
elements does not imply that only two elements may be employed, or
that the first element must precede the second element in some
way.
[0328] As used herein the terms "determining" and "determining"
encompass a wide variety of actions. For example, to "decide" and
"determine" as used herein may be interpreted to mean making
decisions and determinations related to calculating, computing,
processing, deriving, investigating, looking up (for example,
searching a table, a database or some other data structure),
ascertaining and so on. Furthermore, to "decide" and "determine" as
used herein may be interpreted to mean making decisions and
determinations related to receiving (for example, receiving
information), transmitting (for example, transmitting information),
inputting, outputting, accessing (for example, accessing data in a
memory) and so on. In addition, to "decide" and "determine" as used
herein may be interpreted to mean making decisions and
determinations related to resolving, selecting, choosing,
establishing, comparing and so on.
[0329] Now, although the present invention has been described in
detail above, it should be obvious to a person skilled in the art
that the present invention is by no means limited to the
embodiments described herein. The present invention can be
implemented with various corrections and in various modifications,
without departing from the spirit and scope of the present
invention defined by the recitations of claims. Consequently, the
description herein is provided only for the purpose of explaining
examples, and should by no means be construed to limit the present
invention in any way.
[0330] The disclosures of Japanese Patent Application No.
2016-073412, filed on Mar. 31, 2016, and Japanese Patent
Application No. 2016-101884, filed on May 20, 2016, including the
specifications, drawings and abstracts, are incorporated herein by
reference in their entirety.
* * * * *