U.S. patent application number 17/057475 was filed with the patent office on 2021-07-01 for terminal, radio communication method, base station, and system.
This patent application is currently assigned to NTT DOCOMO, INC.. The applicant listed for this patent is NTT DOCOMO, INC.. Invention is credited to Yuki Matsumura, Satoshi Nagata, Shohei Yoshioka.
Application Number | 20210203438 17/057475 |
Document ID | / |
Family ID | 1000005474676 |
Filed Date | 2021-07-01 |
United States Patent
Application |
20210203438 |
Kind Code |
A1 |
Matsumura; Yuki ; et
al. |
July 1, 2021 |
TERMINAL, RADIO COMMUNICATION METHOD, BASE STATION, AND SYSTEM
Abstract
A terminal is disclosed including a processor that, if
retransmission of an uplink shared channel is performed, determines
a time density of a phase tracking reference signal (PTRS) based on
whether a modulation and coding scheme (MCS) index is larger than a
certain value; and a transmitter that transmits the PTRS. In other
aspects, a radio communication method, a base station, and a system
are also disclosed.
Inventors: |
Matsumura; Yuki; (Tokyo,
JP) ; Yoshioka; Shohei; (Tokyo, JP) ; Nagata;
Satoshi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NTT DOCOMO, INC. |
Tokyo |
|
JP |
|
|
Assignee: |
NTT DOCOMO, INC.
Tokyo
JP
|
Family ID: |
1000005474676 |
Appl. No.: |
17/057475 |
Filed: |
May 23, 2019 |
PCT Filed: |
May 23, 2019 |
PCT NO: |
PCT/JP2019/020402 |
371 Date: |
November 20, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 1/0004 20130101;
H04L 1/189 20130101; H04W 72/0446 20130101; H04W 72/042 20130101;
H04L 5/0048 20130101 |
International
Class: |
H04L 1/00 20060101
H04L001/00; H04L 5/00 20060101 H04L005/00; H04L 1/18 20060101
H04L001/18; H04W 72/04 20060101 H04W072/04 |
Foreign Application Data
Date |
Code |
Application Number |
May 23, 2018 |
JP |
2018-110697 |
Claims
1.-3. (canceled)
4. A terminal comprising: a processor that, if retransmission of an
uplink shared channel is performed, determines a time density of a
phase tracking reference signal (PTRS) based on whether a
modulation and coding scheme (MCS) index is larger than a certain
value; and a transmitter that transmits the PTRS.
5. The terminal according to claim 4, wherein if the MCS index is
larger than the certain value, the processor determines the time
density of the PTRS based on the MCS index, notified in an initial
transmission, that is smaller than or equal to the certain
value.
6. The terminal according to claim 4, wherein the time density of
the PTRS is determined according to an MCS index threshold
indicated in a higher layer.
7. A radio communication method comprising: if retransmission of an
uplink shared channel is performed, determining a time density of a
phase tracking reference signal (PTRS) based on whether a
modulation and coding scheme (MCS) index is larger than a certain
value; and transmitting the PTRS.
8. A base station comprising: a processor that controls
retransmission of an uplink shared channel; and a receiver that, if
the retransmission of the uplink shared channel is performed,
receives a phase tracking reference signal (PTRS) whose time
density is determined based on whether a modulation and coding
scheme (MCS) index is larger than a certain value.
9. The terminal according to claim 5, wherein the time density of
the PTRS is determined according to an MCS index threshold
indicated in a higher layer.
10. A system comprising a terminal and a base station, wherein the
terminal comprises: a processor of the terminal that, if
retransmission of an uplink shared channel is performed, determines
a time density of a phase tracking reference signal (PTRS) based on
whether a modulation and coding scheme (MCS) index is larger than a
certain value; and a transmitter that transmits the PTRS, the base
station comprises: a processor of the base station that controls
the retransmission of an uplink shared channel; and a receiver
that, if the retransmission of the uplink shared channel is
performed, receives the PTRS whose time density is determined based
on whether the MCS index is larger than the certain value.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a user terminal and a
radio communication method in next-generation mobile communication
systems.
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 latency and so on (see Non-Patent Literature
1). For the purpose of further high capacity, advancement of LTE
(LTE Rel. 8, Rel. 9), and so on, the specifications of LTE-A
(LTE-Advanced, LTE Rel. 10, Rel. 11, Rel. 12, Rel. 13) have been
drafted.
[0003] Successor systems of LTE (referred to as, for example, "FRA
(Future Radio Access)," "5G (5th generation mobile communication
system)," "5G+ (plus)," "NR (New Radio)," "NX (New radio access),"
"FX (Future generation radio access)," "LTE Rel. 14," "LTE Rel. 15"
(or later versions), and so on) are also under study.
[0004] In the existing LTE systems (for example, 3GPP Rel. 8 to
Rel. 14), a user terminal (UE (User Equipment)) controls reception
of a downlink shared channel (for example, PDSCH (Physical Downlink
Shared Channel)), based on downlink control information (DCI) (also
referred to as the DL assignment, or the like) from a radio base
station. A user terminal also controls transmission of an uplink
shared channel (for example, PUSCH (Physical Uplink Shared
Channel)), based on DCI (also referred to as the UL grant, or the
like).
CITATION LIST
Non-Patent Literature
[0005] Non-Patent Literature 1: 3GPP TS 36.300 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
SUMMARY OF INVENTION
Technical Problem
[0006] With regard to future radio communication systems (for
example, NR), a study is underway about transmission of phase
tracking reference signals (PTRS) by base stations (for example,
gNBs) in the downlink. Moreover, a study is underway about
controlling the time domain density of PTRS based on a modulation
and coding scheme (MCS) index that is indicated in DCI.
[0007] However, how an MCS index is determined when uplink control
information (UCI) is transmitted utilizing an uplink shared channel
(for example, PUSCH) in which UL data (for example, UL-SCH) are not
multiplexed (UCI on PUSCH without data) has not been fully
discussed. This leads to a problem of how to determine the time
domain density of PTRS. A failure of appropriate transmission of
PTRS (for example, a case that the time domain density of PTRS is
failed to be appropriately determined) may deteriorate
communication quality.
[0008] Thus, an object of the present disclosure is to provide a
user terminal and a radio communication method that can
appropriately control transmission of PTRS.
Solution to Problem
[0009] A user terminal according to an aspect of the present
disclosure includes: a control section that controls, when
retransmitting an uplink shared channel, determination of time
density of a phase tracking reference signal (PTRS) based on
whether a modulation and coding scheme (MCS) index is included in a
range that is larger than a certain value; and a transmitting
section that transmits the PTRS.
Advantageous Effects of Invention
[0010] According to an aspect of the present disclosure, it is
possible to appropriately control transmission of PTRS.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a diagram to show an example of an MCS table;
[0012] FIG. 2 is a diagram to show an example of the MCS table;
[0013] FIG. 3 is a diagram to show an example of the MCS table;
[0014] FIG. 4 is a diagram to show an example of a table
representing correspondence between MCS indices and time domain
densities of PTRS;
[0015] FIG. 5 is a diagram to show an example of determination of
the time domain density of PTRS;
[0016] FIG. 6 is a diagram to show another example of determination
of the time domain density of PTRS;
[0017] FIG. 7 is a diagram to show still another example of
determination of the time domain density of PTRS;
[0018] FIG. 8 is a diagram to show an example of a schematic
structure of a radio communication system according to one
embodiment;
[0019] FIG. 9 is a diagram to show an example of an overall
structure of a radio base station according to one embodiment;
[0020] FIG. 10 is a diagram to show an example of a functional
structure of the radio base station according to one
embodiment;
[0021] FIG. 11 is a diagram to show an example of an overall
structure of a user terminal according to one embodiment;
[0022] FIG. 12 is a diagram to show an example of a functional
structure of a user terminal according to one embodiment; and
[0023] FIG. 13 is a diagram to show an example of a hardware
structure of the radio base station and the user terminal according
to one embodiment.
DESCRIPTION OF EMBODIMENTS
[0024] In NR, a base station (for example, gNB) transmits a phase
tracking reference signal (PTRS) in the downlink. The base station
may transmit the PTRS, for example, by continuously or
discontinuously mapping the PTRS in a time direction in one
subcarrier. The base station may transmit the PTRS during at least
part of a period (a slot, a symbol. or the like) for transmitting a
downlink shared channel (PDSCH (Physical Downlink Shared Channel)).
The PTRS transmitted by the base station may also be referred to as
a DL PTRS.
[0025] A UE transmits a phase tracking reference signal (PTRS) in
the uplink. The UE may transmit the PTRS, for example, by
continuously or discontinuously mapping the PTRS in a time
direction in one subcarrier. The UE may transmit the PTRS during at
least part of a period (a slot, a symbol. or the like) for
transmitting an uplink shared channel (PUSCH (Physical Uplink
Shared Channel)). The PTRS transmitted by the UE may also be
referred to as a UL PTRS. Hereinafter, the UL PTRS is simply
referred to as PTRS.
[0026] The UE may determine whether there is a PTRS in the uplink,
based on the configuration of higher layer signaling (for example,
the presence (or absence) of a PTRS-UplinkConfig information
element). The UE may assume that there is a PTRS in a resource
block for PUSCH. The base station may determine a phase noise and
correct a phase error in a received signal, based on the PTRS
transmitted from the UE.
[0027] Here, for example, the higher layer signaling may be any one
or combinations of RRC (Radio Resource Control) signaling, MAC
(Medium Access Control) signaling, broadcast information, and the
like.
[0028] For example, the MAC signaling may use MAC control elements
(MAC CE), MAC PDUs (Protocol Data Units), and the like. The
broadcast information may be, for example, master information
blocks (MIBs), system information blocks (SIBs), minimum system
information (RMSI (Remaining Minimum System Information)), other
system information (OSI), and the like.
[0029] With regard to NR, a study is underway about controlling at
least one of a modulation method (or a modulation order) and a
coding rate (modulation order/coding rate) of a physical uplink
shared channel (for example, PUSCH (Physical Uplink Shared
Channel)) that is scheduled by downlink control information (DCI),
based on a certain field (for example, a modulation and coding
scheme (MCS) field) included in the DCI (UL grant, for example, DCI
format 0_0, 0_1).
[0030] Specifically, a study is underway about determination, by a
user terminal (UE (User Equipment), of a modulation order/coding
rate for PUSCH corresponding to an MCS index indicated in the MCS
field of the DCI by using a table (an MCS table) that associates
MCS indices with modulation orders and TBS indices.
[0031] Here, each modulation order is a value corresponding to each
modulation method. For example, the modulation orders of QPSK
(Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude
Modulation), 64QAM and 256QAM are respectively defined as 2, 4, 6
and 8.
[0032] FIGS. 1 to 3 are diagrams to show examples of the MCS table.
Note that the values in the MCS tables illustrated in FIGS. 1 to 3
are only examples without limiting to these values. Some of the
items (for example, the spectral efficiency) associated with the
MCS index (I.sub.MCS) may be omitted or another item may be
added.
[0033] The user terminal may determine an MCS table to be used to
determine a modulation order/coding rate for PUSCH by using at
least one of following conditions (1) to (3): [0034] (1) Transform
precoding is enabled or not (whether DFT-Spread-OFDM (DFT-s-OFDM
(Discrete Fourier Transform-Spread-Orthogonal Frequency Division
Multiplexing)) waveform or OFDM waveform is adopted); [0035] (2)
Information indicating the MCS table (MCS table information) to be
used by the user terminal indicates a specific modulation method
(for example, 256QAM) or not; and [0036] (3) Which RNTI (Radio
Network Temporary Identifier) is used for DCI with CRC that is
scrambled (CRC-scrambled) with the RNTI.
[0037] For example, when the DCI (for example, DCI format 0_0 or
0_1) is CRC-scrambled with a specific RNTI (for example, C-RNTI,
TC-RNTI, or CS-RNTI), transform precoding is disabled, as well as,
the MCS table information does not indicate 256QAM, the user
terminal may determine a modulation order/coding rate corresponding
to the MCS index (I.sub.MCS) in the DCI by using the table shown in
FIG. 1.
[0038] When transform precoding is disabled, as well as, the MCS
table information indicates 256QAM, the user terminal may determine
the modulation order/coding rate corresponding to the MCS index
(I.sub.MCS) in the DCI by using the table shown in FIG. 2.
[0039] When transform precoding is enabled, as well as, the MCS
table information does not indicate 256QAM, the user terminal may
determine a modulation order/coding rate corresponding to the MCS
index (I.sub.MCS) in the DCI by using the table shown in FIG.
3.
[0040] Note that, for example, when the user terminal satisfies a
specific condition in FIG. 3 (for example, BPSK is supported), the
modulation order q corresponding to the specific MCS index (for
example, 0, 1) may be 1 (BPSK). When the above-described specific
condition is not satisfied, the modulation order q may be 2
(QPSK).
[0041] When transform precoding is enabled, as well as, the MCS
table information indicates 256QAM, the user terminal may determine
the modulation order/coding rate corresponding to the MCS index
(I.sub.MCS) in the DCI by using the table shown in FIG. 2.
[0042] Note that the conditions of using the tables shown in FIGS.
1 to 3 are not limited to the above conditions.
[0043] Further, with regard to NR, a study is underway about
determination of the time domain density of PTRS, based on an MCS
index indicated in DCI, by referring to a certain table.
[0044] FIG. 4 illustrates a table which defines correspondence
between MCS indices (for example, the ranges of MCS indices) and
the time densities of PTRS (hereinafter, also referred to as a
certain table). For example, the time density of PTRS is 4 when the
MCS index indicated in the DCI is not less than MCS 1 and less than
MCS 2; the time density of PTRS is 2 when the MCS index is not less
than MCS 2 and less than MCS 3, and the time density of PTRS is 1
when the MCS index is not less than MCS 3 and less than MCS 4. It
is to be understood that the correspondence relationships between
MCS indices and time densities (or time domain densities) of PTRS
are not limited to these.
[0045] NR supports a channel state information (CSI) report that
transmits as feedback, to a radio base station, the result of
measurement of a channel state by the user terminal based on a
reference signal for measurement as CSI at a certain timing.
[0046] The reference signal for measuring a channel state may also
be referred to as, for example, CSI-RS (Channel State
Information-Reference Signal) without limitation. The CSI may
include at least one of CQI (Channel Quality Indicator), PMI
(Precoding Matrix Indicator) and RI (Rank Indicator). The CSI may
also include at least one of first CSI (CSI part 1) and second CSI
(CSI part 2).
[0047] The supported CSI reports include: a periodic CSI report
(P-CSI report), a CSI report using semi-persistently specified
resources (SP-CSI report), and an aperiodic CSI report (A-CSI
report).
[0048] When transmitting the A-CSI report, the UE transmits the
A-CSI according to a CSI trigger (a CSI request) from a radio base
station. For example, the UE transmits an A-CSI report at a certain
timing (for example, 4 subframes) after receiving the CSI
trigger.
[0049] The A-CSI trigger is included in downlink control
information (DCI) that is transmitted using a downlink control
channel (PDCCH (Physical Downlink Control Channel)). The DCI that
includes the A-CSI trigger is a UL grant and, for example, is at
least one of DCI formats 0_0 and 0_1.
[0050] In transmitting an A-CSI report, the user terminal transmits
CSI by using a PUSCH that is specified by a UL grant including the
A-CSI trigger. The PUSCH is also referred to as PUSCH without
UL-SCH or the like, when no corresponding transport channel (also,
referred to as UL-SCH (Uplink Shared Channel), uplink data, uplink
user data or the like) exists.
[0051] Whether the PUSCH is PUSCH without UL-SCH or not may be
indicated by a certain field (for example, a UL-SCH indicator
field) in the UL grant. For example, the UL-SCH indicator field is
1 bit which may indicate whether PUSCH without UL-SCH or PUSCH with
UL-SCH is employed.
[0052] In this way, the PUSCH without UL-SCH is used for
transmission of uplink control information (for example, A-CSI) and
may transmit a data content different from a data content
transmitted on the PUSCH with UL-SCH (for example, at least one of
uplink user data and higher layer control information).
[0053] It is conceivable that the determination method of the
modulation order/coding rate of PUSCH may be configured differently
for PUSCH with UL-SCH and for PUSCH without UL-SCH.
[0054] As such, how the MCS index is determined by DCI has not been
sufficiently discussed with regard to UCI on PUSCH without data
(for example, A-CSI on PUSCH without data). This leads to a problem
of how to control the time domain density of PTRS for the UCI on
PUSCH without data.
[0055] For example, in UCI on PUSCH without data (for example,
A-CSI on PUSCH without data), when a certain MCS index (for
example, an MCS index in a first range (=0 to 27)) is indicated,
the time domain density of PTRS is determined according to a
certain table.
[0056] Whereas, in a case of PUSCH transmission (at least including
a case of UCI on PUSCH without data), any of MCS indices of 0 to 27
or any of MCS indices of 28 to 31 may be indicated in
retransmission. For example, it is conceivable that a value that is
not defined in a certain table (for example, MCS index of 30 or the
like) is indicated. In other words, how to control PTRS
transmission (for example, the time domain density of PTRS) in
retransmission (for example, retransmission of at least one of
PUSCH and UCI) is a problem.
[0057] Thus, the inventors of the present invention came up with
the idea of controlling the method of determining the time domain
density of PTRS, based on a region in which the indicated MCS index
is included (for example, included in either a first range or a
second range). The first range may be MCS index 0 to 27, and the
second range may be MCS index 28 to 31. Alternatively, the first
range may be MCS index 0 to 28, and the second range may be MCS
index 29 to 31. It is to be understood that the MCS indices are not
limited to these examples.
[0058] Embodiments according to the present disclosure will be
described in detail with reference to the drawings as follows. The
aspects according to the present embodiment may be employed
independently or may be employed in combination. Although the
following configuration will be described using PUSCH transmission
without data (for example, UL-SCH) as an example, the configuration
may be applied to PUSCH transmission with data. The following
configuration may be applied to CP-OFDM or DFT-S-OFDM. The
following configuration may be applied to DL transmission or
signals other than the PTRS.
(First Aspect)
[0059] In a first aspect, the time density of PTRS in
retransmission (for example, PUSCH retransmission) is determined
using a range in which the MCS index is included and at least one
of certain rules.
[0060] In retransmission, when a indicated MCS index is included in
a first range (for example, 0 to 27 (or 0 to 28)), the UE
determines the time domain density of PTRS, based on the indicated
MCS index and a certain table (for example, FIG. 4).
[0061] The UE may determine that the transmission is retransmission
when the value of a new data indicator field included in the DCI
indicated to the UE is different from the value of the same field
in the previous DCI. For example, the UE may determine that the
transmission is retransmission when the value of the new data
indicator field in the indicated DCI has changed from 0 to 1 or 1
to 0.
[0062] Whereas, when the MCS index is included in the first range
(for example, 28 to 31 (or 29 to 31)), the UE may adopt at least
one of following rules 1-1, 1-2, and 1-3.
<Rule 1-1>
[0063] The UE uses the time domain density of PTRS adopted in
initial transmission. In this case, the UE also adopts, in
retransmission, the time density of PTRS corresponding to the MCS
index (for example, any of 0 to 27) indicated in the initial
transmission.
[0064] In this way, the time density of PTRS can be appropriately
determined in retransmission, even if the time density of PTRS is a
value that is not defined as an MCS index in a certain table.
<Rule 1-2>
[0065] The UE determines time domain density according to a certain
conversion method, based on the time domain density of PTRS adopted
in initial transmission.
[0066] For example, the UE uses the time domain density of PTRS in
a different row in a certain table (for example, FIG. 4) from the
row adopted in the initial transmission. As an example, the UE uses
the time domain density of PTRS in a row up or down the row adopted
in the initial transmission.
[0067] Setting the time domain density of PTRS adopted in
retransmission smaller than the time domain density in initial
transmission, lowers the coding rate, thereby improving
characteristics. On the other hand, setting the time domain density
of PTRS adopted in retransmission larger than the time domain
density in initial transmission, facilitates gaining of phase noise
correction effects more effectively and improves
characteristics.
<Rule 1-3>
[0068] The UE determines the time domain density of PTRS by using
an MCS index indicated in retransmission, a certain table, and a
certain conversion formula (refer to FIGS. 5 to 7). FIG. 5
corresponds to a table that is used in initial transmission, and
FIGS. 6 and 7 correspond to tables that are used in the
retransmission. In this example, the MCS index that is used
(indicated to the UE) in the initial transmission is within the
range of 0 to 27, and the MCS index that is used (indicated to the
UE) in the retransmission is within the range of 28 to 31, without
limitation to these.
[0069] For example, the UE may determine the time domain density of
PTRS in retransmission according to a modulation order indicated
with the MCS index of 28 to 31 and an MCS index threshold that is
indicated in a higher layer.
[0070] In this example, as the MCS index thresholds that are
indicated in a higher layer (for example, RRC signaling), values
between MCS indices 4 and 5, between MCS indices 11 and 12, and
between MCX indices 19 and 20 are exemplified, without limiting the
thresholds and configured values of MCS indices to these.
[0071] FIGS. 6 and 7 show a case where the UE determines the time
domain density of PTRS in retransmission, based on the modulation
order which corresponds to the indicated MCS index (any of 28 to
31) (in this example, 28 corresponds to `q;` 29, `2;` 30, `4;` and
31, `6`).
[0072] For example, in FIG. 6, the UE assumes that there is no PTRS
(no presence of PTRS) when the modulation order is `q` (MCS
index=28). The UE assumes that the time domain density of PTRS is 4
when the modulation order is `2` (MCS index=29). The UE assumes
that the time domain density of PTRS is 2 when the modulation order
is `4` (MCS index=30). The UE assumes that the time domain density
of PTRS is 1 when the modulation order is `6` (MCS index=31).
[0073] In FIG. 7, the UE assumes that there is no PTRS (no presence
of PTRS) when the MCS index is 28. The UE assumes that the time
domain density of PTRS is 4 when the MCS index is 29. The UE
assumes that the time domain density of PTRS is 2 when the MCS
index is 30.
[0074] Alternatively, in FIG. 7, the UE assumes that there is no
PTRS (no presence of PTRS) when the MCS index is 28 or 29. The UE
assumes that the time domain density of PTRS is 4 when the MCS
index is 30. The UE may assume that the time domain density of PTRS
is 2 when the MCS index is 31.
[0075] In this way, when an MCS index within the range of 28 to 31
is indicated in retransmission, the time density of PTRS can be
appropriately determined by determining the time domain density of
PTRS by using the MCS index, a certain table, and a certain
conversion formula, even if the value is not defined in the certain
table.
(Second Aspect)
[0076] In a second aspect, the time domain density of PTRS is
determined in accordance with a certain rule when an MCS index
indicated in initial transmission is included in a certain range
(for example, 28 to 31 (or 29 to 31)).
[0077] For example, in the initial transmission, when an MCS index
included in DCI is included in a certain range (for example, 28 to
31), the UE determines the time domain density of PTRS according to
the indicated MCS index, a certain table, and a certain conversion
formula (refer to FIG. 5). For example, the UE may adopt rule 1-3
in the above-described first aspect (retransmission may be replaced
with initial transmission).
[0078] For example, the UE may determine the time domain density of
PTRS according to a indicated MCS index and an MCS index threshold
that is indicated in a higher layer. As an example, the UE assumes
that there is no PTRS (no presence of PTRS) when the indicated MCS
index is 28. The UE assumes that the time domain density of PTRS is
4 when the MCS index is 29. The UE assumes that the time domain
density of PTRS is 2 when the MCS index is 30. The UE assumes that
the time domain density of PTRS is 1 when the MCS index is 31.
[0079] In this way, the time density of PTRS can be appropriately
determined, even if the value that is indicated in initial
transmission is not defined in a certain table as an MCS index.
(Variation)
[0080] The value of PTRS-UL configuration (for example,
PTRS-UplinkConfig) indicated from a base station to the UE may use
0 to 27. In this way, unnecessary RRC bits can be removed compared
with a case of configuring PTRS-UplinkConfig in the range of 0-29
as has been conventionally considered. The PTRS-UL configuration
may be transmitted using a higher layer (for example, RRC signaling
or the like).
(Radio Communication System)
[0081] Hereinafter, a structure of a radio communication system
according to the embodiment of the present disclosure will be
described. In this radio communication system, the radio
communication method illustrated in above-described embodiment may
be used alone or may be used in combination for communication.
[0082] FIG. 8 is a diagram to show an example of a schematic
structure of the radio communication system according to one
embodiment. 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 system bandwidth in an LTE system (for example, 20 MHz)
constitutes one unit.
[0083] Note that the radio communication system 1 may be referred
to as "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)," "NR (New Radio)," "FRA (Future Radio
Access)," "New-RAT (Radio Access Technology)," and so on, or may be
referred to as a system implementing these.
[0084] The radio communication system 1 includes a radio base
station 11 that forms a macro cell C1 of a relatively wide
coverage, 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. The arrangement,
the number, and the like of each cell and user terminal 20 are by
no means limited to the aspect shown in the diagram.
[0085] The user terminals 20 can connect with both the radio base
station 11 and the radio base stations 12. It is assumed that the
user terminals 20 use the macro cell C1 and the small cells C2 at
the same time by means of CA or DC. The user terminals 20 can
execute CA or DC by using a plurality of cells (CCs) (for example,
five CCs or less, or six CCs or more).
[0086] Between the user terminals 20 and the radio base station 11,
communication can be carried out by 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 between the
user terminals 20 and 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.
[0087] The user terminals 20 can perform communication by using
time division duplex (TDD) and/or frequency division duplex (FDD)
in each cell. Furthermore, in each cell (carrier), a single
numerology may be employed, or a plurality of different
numerologies may be employed.
[0088] Numerologies may be communication parameters applied to
transmission and/or reception of a certain signal and/or channel,
and for example, may indicate at least one of a subcarrier spacing,
a bandwidth, a symbol length, a cyclic prefix length, a subframe
length, a TTI length, the number of symbols per TTI, a radio frame
structure, a particular filter processing performed by a
transceiver in a frequency domain, a particular windowing
processing performed by a transceiver in a time domain, and so
on.
[0089] For example, if certain physical channels use different
subcarrier spacings of the OFDM symbols constituted and/or
different numbers of the OFDM symbols, it may be referred to as
that the numerologies are different.
[0090] A wired connection (for example, means in compliance with
the CPRI (Common Public Radio Interface) such as an optical fiber,
an X2 interface and so on) or a wireless connection may be
established between the radio base station 11 and the radio base
stations 12 (or between two radio base stations 12).
[0091] The radio base station 11 and the radio base stations 12 are
each connected with a 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.
[0092] 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. 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.
[0093] Each of the user terminals 20 is a terminal that supports
various communication schemes such as LTE and LTE-A, and may
include not only mobile communication terminals (mobile stations)
but stationary communication terminals (fixed stations).
[0094] In the radio communication system 1, as radio access
schemes, orthogonal frequency division multiple access (OFDMA) is
applied to the downlink, and single carrier frequency division
multiple access (SC-FDMA) and/or OFDMA is applied to the
uplink.
[0095] OFDMA is a multi-carrier communication scheme to perform
communication by dividing a frequency band into a plurality of
narrow frequency bands (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 combinations of these, and
other radio access schemes may be used.
[0096] 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, SIBs (System Information Blocks) and so on are
communicated on the PDSCH. The MIBs (Master Information Blocks) are
communicated on the PBCH.
[0097] The downlink L1/L2 control channels include at least one of
a downlink control channels (a PDCCH (Physical Downlink Control
Channel), and/or an EPDCCH (Enhanced Physical Downlink Control
Channel)), a PCFICH (Physical Control Format Indicator Channel),
and a PHICH (Physical Hybrid-ARQ Indicator Channel). Downlink
control information (DCI), including PDSCH and/or PUSCH scheduling
information, and so on are communicated on the PDCCH.
[0098] Note that the scheduling information may be indicated by the
DCI. For example, the DCI scheduling DL data reception may be
referred to as "DL assignment," and the DCI scheduling UL data
transmission may be referred to as "UL grant."
[0099] The number of OFDM symbols to use for the PDCCH is
communicated on the PCFICH. Transmission confirmation information
(for example, also referred to as "retransmission control
information," "HARQ-ACK," "ACK/NACK," and so on) of HARQ (Hybrid
Automatic Repeat reQuest) to a PUSCH is transmitted on the PHICH.
The EPDCCH is frequency-division multiplexed with the PDSCH
(downlink shared data channel) and used to communicate DCI and so
on, like the PDCCH.
[0100] 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. User data, higher layer control information and so
on are communicated on the PUSCH. In addition, radio link quality
information (CQI (Channel Quality Indicator)) of the downlink,
transmission confirmation information, scheduling request (SR), and
so on are transmitted on the PUCCH. By means of the PRACH, random
access preambles for establishing connections with cells are
communicated.
[0101] In the radio communication system 1, a cell-specific
reference signal (CRS), a channel state information-reference
signal (CSI-RS), a demodulation reference signal (DMRS), a
positioning reference signal (PRS), and so on are transmitted as
downlink reference signals. In the radio communication system 1, a
measurement reference signal (SRS (Sounding Reference Signal)), a
demodulation reference signal (DMRS), and so on are transmitted as
uplink reference signals. Note that DMRS may be referred to as a
"user terminal specific reference signal (UE-specific Reference
Signal)." Transmitted reference signals are by no means limited to
these.
<Radio Base Station>
[0102] FIG. 9 is a diagram to show an example of an overall
structure of the radio base station according to one embodiment. A
radio base station 10 includes 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 transmission line
interface 106. Note that the radio base station 10 may be
configured to include one or more transmitting/receiving antennas
101, one or more amplifying sections 102 and one or more
transmitting/receiving sections 103.
[0103] User data to be transmitted from the radio base station 10
to the user terminal 20 by the downlink is input from the higher
station apparatus 30 to the baseband signal processing section 104,
via the transmission line interface 106.
[0104] In the baseband signal processing section 104, the user data
is subjected to transmission processes, such as 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 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 section 103.
Furthermore, downlink control signals are also subjected to
transmission processes such as channel coding and inverse fast
Fourier transform, and the result is forwarded to each
transmitting/receiving section 103.
[0105] The transmitting/receiving sections 103 convert baseband
signals that are pre-coded and output from the baseband signal
processing section 104 on a per antenna basis, to have radio
frequency bands and transmit the result. 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. The transmitting/receiving sections 103 can be
constituted with 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 disclosure pertains. Note that each transmitting/receiving
section 103 may be structured as a transmitting/receiving section
in one entity, or may be constituted with a transmitting section
and a receiving section.
[0106] Meanwhile, as for uplink signals, radio frequency signals
that are received in the transmitting/receiving antennas 101 are
amplified in the amplifying sections 102. The
transmitting/receiving sections 103 receive the uplink signals
amplified in the amplifying sections 102. The
transmitting/receiving sections 103 convert the received signals
into the baseband signal through frequency conversion and outputs
to the baseband signal processing section 104.
[0107] 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 transmission line interface 106. The call
processing section 105 performs call processing (setting up,
releasing and so on) for communication channels, manages the state
of the radio base station 10, manages the radio resources and so
on.
[0108] The transmission line interface 106 transmits and/or
receives signals to and/or from the higher station apparatus 30 via
a certain interface. The transmission line interface 106 may
transmit and/or receive signals (backhaul signaling) with other
radio base stations 10 via an inter-base station interface (for
example, an optical fiber in compliance with the CPRI (Common
Public Radio Interface) and an X2 interface).
[0109] The transmitting/receiving sections 103 receives a phase
tracking reference signal (PTRS) for an uplink control channel that
is used in transmission of uplink control information without
data.
[0110] FIG. 10 is a diagram to show an example of a functional
structure of the radio base station according to one embodiment.
Note that, the present example primarily shows functional blocks
that pertain to characteristic parts of the present embodiment, and
it is assumed that the radio base station 10 may include other
functional blocks that are necessary for radio communication as
well.
[0111] The baseband signal processing section 104 at least includes
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
structures may be included in the radio base station 10, and some
or all of the structures do not need to be included in the baseband
signal processing section 104.
[0112] The control section (scheduler) 301 controls the whole of
the radio base station 10. The control section 301 can be
constituted with a controller, a control circuit or control
apparatus that can be described based on general understanding of
the technical field to which the present disclosure pertains.
[0113] The control section 301, for example, controls the
generation of signals in the transmission signal generation section
302, the mapping of signals by the mapping section 303, and so on.
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.
[0114] The control section 301 controls the scheduling (for
example, resource assignment) of system information, a downlink
data signal (for example, a signal transmitted on the PDSCH), a
downlink control signal (for example, a signal transmitted on the
PDCCH and/or the EPDCCH. Transmission confirmation information, and
so on). Based on the results of determining necessity or not of
retransmission control to the uplink data signal, or the like, the
control section 301 controls generation of a downlink control
signal, a downlink data signal, and so on.
[0115] The control section 301 controls the scheduling of a
synchronization signal (for example, PSS/SSS), a downlink reference
signal (for example, CRS, CSI-RS, DMRS), and so on.
[0116] The control section 301 determines a determination method of
the time domain density of PTRS in the UE, based on whether a
modulation and coding scheme (MCS) index indicated in the downlink
control information is included in a certain range (for example,
either the first range or the second range).
[0117] 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 the downlink signals to the mapping
section 303. The transmission signal generation section 302 can be
constituted with a signal generator, a signal generation circuit or
signal generation apparatus that can be described based on general
understanding of the technical field to which the present
disclosure pertains.
[0118] For example, the transmission signal generation section 302
generates DL assignment to report assignment information of
downlink data and/or UL grant to report assignment information of
uplink data, based on commands from the control section 301. The DL
assignment and the UL grant are both DCI, and follow the DCI
format. For a downlink data signal, encoding processing and
modulation processing are performed in accordance with a coding
rate, modulation scheme, or the like determined based on channel
state information (CSI) or the like from each user terminal 20.
[0119] The mapping section 303 maps the downlink signals generated
in the transmission signal generation section 302 to certain 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 with a mapper, a mapping
circuit or mapping apparatus that can be described based on general
understanding of the technical field to which the present
disclosure pertains.
[0120] 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
are, for example, uplink signals that are transmitted from the user
terminals 20 (uplink control signals, uplink data signals, uplink
reference signals and so on). The received signal processing
section 304 can be constituted with 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 disclosure pertains.
[0121] The received signal processing section 304 outputs the
decoded information acquired through the receiving processes to the
control section 301. For example, if the received signal processing
section 304 receives the PUCCH including HARQ-ACK, the received
signal processing section 304 outputs the HARQ-ACK to the control
section 301. The received signal processing section 304 outputs the
received signals and/or the signals after the receiving processes
to the measurement section 305.
[0122] The measurement section 305 conducts measurements with
respect to the received signals. The measurement section 305 can be
constituted with a measurer, a measurement circuit or measurement
apparatus that can be described based on general understanding of
the technical field to which the present disclosure pertains.
[0123] For example, the measurement section 305 may perform RRM
(Radio Resource Management) measurement, CSI (Channel State
Information) measurement, and so on, based on the received signal.
The measurement section 305 may measure a received power (for
example, RSRP (Reference Signal Received Power)), a received
quality (for example, RSRQ (Reference Signal Received Quality), an
SINR (Signal to Interference plus Noise Ratio), an SNR (Signal to
Noise Ratio)), a signal strength (for example, RSSI (Received
Signal Strength Indicator)), channel information (for example,
CSI), and so on. The measurement results may be output to the
control section 301.
<User Terminal>
[0124] FIG. 11 is a diagram to show an example of an overall
structure of a user terminal according to one embodiment. A user
terminal 20 includes 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 the user terminal 20 may be configured to include
one or more transmitting/receiving antennas 201, one or more
amplifying sections 202 and one or more transmitting/receiving
sections 203.
[0125] 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
transmitting/receiving sections 203 convert the received signals
into baseband signals through frequency conversion, and output the
baseband signals to the baseband signal processing section 204. The
transmitting/receiving sections 203 can be constituted with
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
disclosure pertains. Note that each transmitting/receiving section
203 may be structured as a transmitting/receiving section in one
entity, or may be constituted with a transmitting section and a
receiving section.
[0126] The baseband signal processing section 204 performs, on each
input baseband signal, an FFT process, error correction decoding, a
retransmission control receiving process, and so on. The 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. In the
downlink data, broadcast information may be also forwarded to the
application section 205.
[0127] Meanwhile, the 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.
[0128] The transmitting/receiving sections 203 convert the baseband
signals output from the baseband signal processing section 204 to
have radio frequency band and transmit the result. The radio
frequency signals having been 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.
[0129] The transmitting/receiving sections 203 transmits a phase
tracking reference signal (PTRS) for an uplink control channel that
is used in transmission of uplink control information without
data.
[0130] FIG. 12 is a diagram to show an example of a functional
structure of a user terminal according to one embodiment. Note
that, the present example primarily shows functional blocks that
pertain to characteristic parts of the present embodiment, and it
is assumed that the user terminal 20 may include other functional
blocks that are necessary for radio communication as well.
[0131] The baseband signal processing section 204 provided in the
user terminal 20 at least includes 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 structures may be included in the user
terminal 20, and some or all of the structures do not need to be
included in the baseband signal processing section 204.
[0132] The control section 401 controls the whole of the user
terminal 20. The control section 401 can be constituted with a
controller, a control circuit or control apparatus that can be
described based on general understanding of the technical field to
which the present disclosure pertains.
[0133] The control section 401, for example, controls the
generation of signals in the transmission signal generation section
402, the mapping of signals by the mapping section 403, and so on.
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.
[0134] The control section 401 acquires a downlink control signal
and a downlink data signal transmitted from the radio base station
10, from the received signal processing section 404. The control
section 401 controls generation of an uplink control signal and/or
an uplink data signal, based on the results of determining
necessity or not of retransmission control to a downlink control
signal and/or a downlink data signal.
[0135] If the control section 401 acquires a variety of information
indicated by the radio base station 10 from the received signal
processing section 404, the control section 401 may update
parameters to use for control, based on the information.
[0136] The control section 401 determines a determination method of
the time domain density of PTRS, based on whether a modulation and
coding scheme (MCS) index indicated in the downlink control
information is included in a certain range (for example, either the
first range or the second range).
[0137] 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 the uplink signals to the mapping section
403. The transmission signal generation section 402 can be
constituted with a signal generator, a signal generation circuit or
signal generation apparatus that can be described based on general
understanding of the technical field to which the present
disclosure pertains.
[0138] For example, the transmission signal generation section 402
generates an uplink control signal about transmission confirmation
information, the channel state information (CSI), and so on, based
on commands from the control section 401. 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 indicated from the
radio base station 10, the control section 401 commands the
transmission signal generation section 402 to generate the uplink
data signal.
[0139] 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 with a mapper, a mapping circuit or
mapping apparatus that can be described based on general
understanding of the technical field to which the present
disclosure pertains.
[0140] 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
are, for example, downlink signals transmitted from the radio base
station 10 (downlink control signals, downlink data signals,
downlink reference signals and so on). The received signal
processing section 404 can be constituted with 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 disclosure pertains. The received signal
processing section 404 can constitute the receiving section
according to the present disclosure.
[0141] 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. The
received signal processing section 404 outputs the received signals
and/or the signals after the receiving processes to the measurement
section 405.
[0142] The measurement section 405 conducts measurements with
respect to the received signals. The measurement section 405 can be
constituted with a measurer, a measurement circuit or measurement
apparatus that can be described based on general understanding of
the technical field to which the present disclosure pertains.
[0143] For example, the measurement section 405 may perform RRM
measurement, CSI measurement, and so on, based on the received
signal. The measurement section 405 may measure a received power
(for example, RSRP), a received quality (for example, RSRQ, SINR,
SNR), a signal strength (for example, RSSI), channel information
(for example, CSI), and so on. The measurement results may be
output to the control section 401.
(Hardware Structure)
[0144] Note that the block diagrams that have been used to describe
the above embodiments show blocks in functional units. These
functional blocks (components) may be implemented in arbitrary
combinations of at least one of hardware and software. Also, the
method for implementing each functional block is not particularly
limited. That is, each functional block may be realized by one
piece of apparatus that is physically or logically coupled, or may
be realized by directly or indirectly connecting two or more
physically or logically separate pieces of apparatus (for example,
via wire, wireless, or the like) and using these plurality of
pieces of apparatus.
[0145] For example, a radio base station, a user terminal, and so
on according to one embodiment of the present disclosure may
function as a computer that executes the processes of the radio
communication method of the present disclosure. FIG. 13 is a
diagram to show an example of a hardware structure of the radio
base station and the user terminal according to one embodiment.
Physically, the above-described radio base station 10 and user
terminals 20 may each be formed as computer apparatus that includes
a processor 1001, a memory 1002, a storage 1003, a communication
apparatus 1004, an input apparatus 1005, an output apparatus 1006,
a bus 1007, and so on.
[0146] Note that, in the following description, the word
"apparatus" may be interpreted as "circuit," "device," "unit," and
so on. The hardware structure of the radio base station 10 and the
user terminals 20 may be designed to include one or a plurality of
apparatuses shown in the drawings, or may be designed not to
include part of pieces of apparatus.
[0147] For example, although only one processor 1001 is shown, a
plurality of processors may be provided. Furthermore, processes may
be implemented with one processor or may be implemented at the same
time, in sequence, or in different manners with one or more
processors. Note that the processor 1001 may be implemented with
one or more chips.
[0148] Each function of the radio base station 10 and the user
terminals 20 is implemented, for example, by allowing certain
software (programs) to be read on hardware such as the processor
1001 and the memory 1002, and by allowing the processor 1001 to
perform calculations to control communication via the communication
apparatus 1004 and control at least one of reading and writing of
data in the memory 1002 and the storage 1003.
[0149] The processor 1001 controls 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.
[0150] Furthermore, the processor 1001 reads programs (program
codes), software modules, data, and so on from at least one of the
storage 1003 and 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 are used. For
example, the control section 401 of each user terminal 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.
[0151] The memory 1002 is a computer-readable recording medium, and
may be constituted with, 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 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 the like for implementing the radio
communication method according to one embodiment of the present
disclosure.
[0152] The storage 1003 is a computer-readable recording medium,
and may be constituted with, 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,
and a key drive), a magnetic stripe, a database, a server, and
other appropriate storage media. The storage 1003 may be referred
to as "secondary storage apparatus."
[0153] The communication apparatus 1004 is hardware
(transmitting/receiving device) for allowing inter-computer
communication via at least one of wired and 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.
The communication apparatus 1004 may be configured to include a
high frequency switch, a duplexer, a filter, a frequency
synthesizer, and so on in order to realize, for example, at least
one of frequency division duplex (FDD) and time division duplex
(TDD). For example, the above-described transmitting/receiving
antennas 101 (201), amplifying sections 102 (202),
transmitting/receiving sections 103 (203), transmission line
interface 106, and so on may be implemented by the communication
apparatus 1004.
[0154] The input apparatus 1005 is an input device that receives
input from the outside (for example, a keyboard, a mouse, a
microphone, a switch, a button, a sensor, and so on). The output
apparatus 1006 is an output device that allows sending output to
the outside (for example, a display, a speaker, an LED (Light
Emitting Diode) lamp, and so on). Note that the input apparatus
1005 and the output apparatus 1006 may be provided in an integrated
structure (for example, a touch panel).
[0155] 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.
[0156] Also, the radio base station 10 and the user terminals 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.
(Variations)
[0157] Note that the terminology described in the present
disclosure and the terminology that is needed to understand the
present disclosure may be replaced by other terms that convey the
same or similar meanings. For example, at least one of "channels"
and "symbols" may be "signals" ("signaling"). Also, "signals" may
be "messages." A reference signal may be abbreviated as an "RS,"
and may be referred to as a "pilot," a "pilot signal," and so on,
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.
[0158] Furthermore, a radio frame may be constituted of one or a
plurality of periods (frames) in the time domain. Each of one or a
plurality of periods (frames) constituting a radio frame may be
referred to as a "subframe." Furthermore, a subframe may be
constituted of one or a plurality of slots in the time domain. A
subframe may have a fixed time length (for example, 1 ms)
independent of numerology.
[0159] Furthermore, a slot may be constituted of one or a plurality
of symbols in the time domain (OFDM (Orthogonal Frequency Division
Multiplexing) symbols, SC-FDMA (Single Carrier Frequency Division
Multiple Access) symbols, and so on). Furthermore, a slot may be a
time unit based on numerology.
[0160] A slot may include a plurality of mini-slots. Each mini-slot
may be constituted of one or a plurality of symbols in the time
domain. A mini-slot may be referred to as a "sub-slot." A mini-slot
may be constituted of symbols less than the number of slots. A
PDSCH and a PUSCH transmitted in a time unit larger than a
mini-slot may be referred to as "PDSCH/PUSCH mapping type A." A
PDSCH and a PUSCH transmitted using a mini-slot may be referred to
as "PDSCH/PUSCH mapping type B."
[0161] A radio frame, a subframe, a slot, a mini-slot, and a symbol
all express time units in signal communication. A radio frame, a
subframe, a slot, a mini-slot, and a symbol may each be called by
other applicable terms. For example, one subframe may be referred
to as a "transmission time interval (TTI)," a plurality of
consecutive subframes may be referred to as a "TTI" or one slot or
one mini-slot may be referred to as a "TTI." That is, at least one
of a subframe and a TTI may be a subframe (1 ms) in existing LTE,
may be a shorter period than 1 ms (for example, 1 to 13 symbols),
or may be a longer period than 1 ms. Note that a unit expressing
TTI may be referred to as a "slot," a "mini-slot," and so on
instead of a "subframe."
[0162] 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 a frequency bandwidth and transmission power that are
available for each user terminal) for the user terminal in TTI
units. Note that the definition of TTIs is not limited to this.
[0163] TTIs may be transmission time units for channel-encoded data
packets (transport blocks), code blocks, or codewords, or may be
the unit of processing in scheduling, link adaptation, and so on.
Note that, when TTIs are given, the time interval (for example, the
number of symbols) to which transport blocks, code blocks,
codewords, or the like are actually mapped may be shorter than the
TTIs.
[0164] Note that, in the case where one slot or one mini-slot is
referred to as a TTI, one or more TTIs (that is, one or more slots
or one or more mini-slots) may be the minimum time unit of
scheduling. Furthermore, the number of slots (the number of
mini-slots) constituting the minimum time unit of the scheduling
may be controlled.
[0165] A TTI having a time length of 1 ms may be referred to as a
"normal TTI" (TTI in LTE Rel. 8 to Rel. 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 "partial or fractional TTI," a "shortened
subframe," a "short subframe," a "mini-slot," a "sub-slot" and so
on.
[0166] Note that a long TTI (for example, a normal TTI, a subframe,
and so on) may be interpreted as a TTI having a time length
exceeding 1 ms, and a short TTI (for example, a shortened TTI and
so on) may be interpreted as a TTI having a TTI length shorter than
the TTI length of a long TTI and equal to or longer than 1 ms.
[0167] 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 a plurality of symbols in the time domain,
and may be one slot, one mini-slot, one subframe, or one TTI in
length. One TTI and one subframe each may be constituted of one or
a plurality of resource blocks. Note that one or a plurality of RBs
may be referred to as a "physical resource block (PRB (Physical
RB))," a "sub-carrier group (SCG)," a "resource element group
(REG)," a "PRB pair," an "RB pair," and so on.
[0168] Furthermore, a resource block may be constituted of one or a
plurality of resource elements (REs). For example, one RE may
correspond to a radio resource field of one subcarrier and one
symbol.
[0169] Note that the above-described structures of radio frames,
subframes, slots, mini-slots, symbols, and so on are merely
examples. For example, structures such as the number of subframes
included in a radio frame, the number of slots per subframe or
radio frame, the number of mini-slots included in a slot, the
numbers of symbols and RBs included in a slot or a mini-slot, the
number of subcarriers included in an RB, the number of symbols in a
TTI, the symbol length, the cyclic prefix (CP) length, and so on
can be variously changed.
[0170] Also, the information, parameters, and so on described in
the present disclosure may be represented in absolute values or in
relative values with respect to certain values, or may be
represented in another corresponding information. For example,
radio resources may be specified by certain indices.
[0171] The names used for parameters and so on in the present
disclosure are in no respect limiting. For example, since various
channels (PUCCH (Physical Uplink Control Channel), PDCCH (Physical
Downlink Control Channel), and so on) and information elements can
be identified by any suitable names, the various names assigned to
these individual channels and information elements are in no
respect limiting.
[0172] The information, signals, and so on described in the present
disclosure may be represented by using any of a variety of
different technologies. For example, data, instructions, commands,
information, signals, bits, symbols, chips, and so on, 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.
[0173] Also, information, signals, and so on can be output in at
least one of from higher layers to lower layers and from lower
layers to higher layers. Information, signals, and so on may be
input and/or output via a plurality of network nodes.
[0174] The information, signals, and so on that are input and/or
output may be stored in a specific location (for example, a memory)
or may be managed by using a management table. 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 another apparatus.
[0175] Reporting of information is by no means limited to the
aspects/embodiments described in the present disclosure, and other
methods may be used as well. For example, reporting of information
may be implemented by using physical layer signaling (for example,
downlink control information (DCI), uplink control information
(UCI), higher layer signaling (for example, RRC (Radio Resource
Control) signaling, broadcast information (master information block
(MIB), system information blocks (SIBs), and so on), MAC (Medium
Access Control) signaling and so on), and other signals and/or
combinations of these.
[0176] Note that physical layer signaling may be referred to as
"L1/L2 (Layer 1/Layer 2) control information (L1/L2 control
signals)," "L1 control information (L1 control signal)," and so on.
Also, RRC signaling may be referred to as an "RRC message," and can
be, for example, an RRC connection setup (RRCConnectionSetup)
message, an RRC connection reconfiguration
(RRCConnectionReconfiguration) message, and so on. Also, MAC
signaling may be reported using, for example, MAC control elements
(MAC CEs).
[0177] Also, reporting of certain information (for example,
reporting of "X holds") does not necessarily have to be reported
explicitly, and can be reported implicitly (by, for example, not
reporting this certain information or reporting another piece of
information).
[0178] Determinations 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 certain value).
[0179] Software, whether referred to as "software," "firmware,"
"middleware," "microcode," or "hardware description language," or
called by other terms, 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.
[0180] 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 at least one of wired technologies (coaxial
cables, optical fiber cables, twisted-pair cables, digital
subscriber lines (DSL), and so on) and wireless technologies
(infrared radiation, microwaves, and so on), at least one of these
wired technologies and wireless technologies are also included in
the definition of communication media.
[0181] The terms "system" and "network" used in the present
disclosure may be used interchangeably.
[0182] In the present disclosure, the terms such as a "base station
(BS)," a "radio base station," a "fixed station," a "NodeB," an
"eNodeB (eNB)," a "gNodeB (gNB)," an "access point," a
"transmission point," a "reception point," a
"transmission/reception point," a "cell," a "sector," a "cell
group," a "carrier," a "component carrier," a "bandwidth part
(BWP)," and so on can be used interchangeably. The base station may
be referred to as the terms such as a "macro cell," a small cell,"
a "femto cell," a "pico cell," and so on.
[0183] A base station can accommodate one or a plurality of (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 of or the entire coverage area of at least one of a base
station and a base station subsystem that provides communication
services within this coverage.
[0184] In the present disclosure, the terms "mobile station (MS),"
"user terminal," "user equipment (UE)," and "terminal," and the
like may be used interchangeably.
[0185] A mobile station may be referred to 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 appropriate terms in some
cases.
[0186] At least one of a base station and a mobile station may be
referred to as a "transmitting apparatus," a "receiving apparatus,"
and so on. Note that at least one of a base station and a mobile
station may be device mounted on a mobile body or a mobile body
itself, and so on. The mobile body may be a vehicle (for example, a
car, an airplane, and the like), may be a mobile body which moves
unmanned (for example, a drone, an automatic operation car, and the
like), or may be a robot (a manned type or unmanned type). Note
that at least one of a base station and a mobile station also
includes an apparatus which does not necessarily move during
communication operation.
[0187] Furthermore, the radio base station in the present
disclosure may be interpreted as a user terminal. For example, each
aspect/embodiment of the present disclosure may be applied to the
structure that replaces a communication between a radio base
station and a user terminal with a communication between a
plurality of user terminals (for example, which may be referred to
as "D2D (Device-to-Device)," "V2X (Vehicle-to-Everything)," and the
like). In this case, the user terminals 20 may have the functions
of the radio base stations 10 described above. The words "uplink"
and "downlink" may be interpreted as the words corresponding to the
terminal-to-terminal communication (for example, "side"). For
example, an uplink channel may be interpreted as a side
channel.
[0188] Likewise, the user terminal in the present disclosure may be
interpreted as radio base station. In this case, the radio base
stations 10 may have the functions of the user terminals 20
described above.
[0189] Actions which have been described in the present disclosure
to be performed by a base station may, in some cases, be performed
by upper nodes. In a network including one or a plurality of
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.
[0190] The aspects/embodiments illustrated in the present
disclosure 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 aspects/embodiments in the present disclosure may be
re-ordered as long as inconsistencies do not arise. For example,
although various methods have been illustrated in the present
disclosure with various components of steps in exemplary orders,
the specific orders that are illustrated herein are by no means
limiting.
[0191] The aspects/embodiments illustrated in the present
disclosure 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), NR(New Radio), NX (New radio access), FX
(Future generation radio access), 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, next-generation
systems that are enhanced based on these and so on. A plurality of
systems may be combined (for example, a combination of LTE or LTE-A
and 5G, and the like) and applied.
[0192] The phrase "based on" (or "on the basis of") as used in the
present disclosure does not mean "based only on" (or "only on the
basis of"), unless otherwise specified. In other words, the phrase
"based on" (or "on the basis of") means both "based only on" and
"based at least on" ("only on the basis of" and "at least on the
basis of").
[0193] Reference to elements with designations such as "first,"
"second," and so on as used in the present disclosure does not
generally limit the quantity or order of these elements. These
designations may be used in the present disclosure 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.
[0194] The term "judging (determining)" as in the present
disclosure herein may encompass a wide variety of actions. For
example, "judging (determining)" may be interpreted to mean making
"judgments (determinations)" about judging, calculating, computing,
processing, deriving, investigating, looking up (for example,
searching a table, a database, or some other data structures),
ascertaining, and so on.
[0195] Furthermore, "judging (determining)" may be interpreted to
mean making "judgments (determinations)" about receiving (for
example, receiving information), transmitting (for example,
transmitting information), input, output, accessing (for example,
accessing data in a memory), and so on.
[0196] In addition, "judging (determining)" as used herein may be
interpreted to mean making "judgments (determinations)" about
resolving, selecting, choosing, establishing, comparing, and so on.
In other words, "judging (determining)" may be interpreted to mean
making "judgments (determinations)" about some action.
[0197] In addition, "judging (determining)" may be interpreted as
"assuming," "expecting," "considering," and the like.
[0198] The terms "connected" and "coupled," or any variation of
these terms as used in the present disclosure mean all direct or
indirect connections or coupling between two or more elements, and
may include the presence of one or more intermediate elements
between two elements that are "connected" or "coupled" to each
other. The coupling or connection between the elements may be
physical, logical, or a combination thereof. For example,
"connection" may be interpreted as "access."
[0199] In the present disclosure, when two elements are connected,
the two elements may be considered "connected" or "coupled" to each
other by using one or more electrical wires, cables, printed
electrical connections, or the like and, as some non-limiting and
non-inclusive examples, by using electromagnetic energy having
wavelengths in radio frequency regions, microwave regions, (both
visible and invisible) optical regions, or the like.
[0200] In the present disclosure, the phrase "A and B are
different" may mean that "A and B are different from each other."
The terms "separate," "be coupled" and so on may be interpreted
similarly.
[0201] When terms such as "include," "including," and variations of
these are used in the present disclosure or in claims, these terms
are intended to be inclusive, in a manner similar to the way the
term "comprising" is used. Furthermore, the term "or" as used in
the present disclosure or in claims is intended to be not an
exclusive disjunction.
[0202] For example, in the present disclosure, when an article such
as "a," "an," and "the" in the English language is added by
translation, the present disclosure may include that a noun after
these articles is in a plural form.
(Supplementary Note)
[0203] Supplementary notes of the present disclosure are added.
<Background Art>
Time Domain Density of PTRS
[0204] Determined based on an MCS index and a certain table.
MCS Index
[0205] Reported in DCI.
UCI on PUSCH Without Data
[0206] How an MCS index is determined in DCI is not defined, and,
thus, there is no method for determining the PTRS time domain
density in UCI on PUSCH without data.
[0207] UL-SCH indicator reports whether there is UL data or not
using 1 bit, and MCS is determined by the I.sub.MCS field bit in
DCI.
<Problem>
[0208] In UCI on PUSCH without data (for example, A-CSI on PUSCH
without data), when an MCS index in the range of 0 to 27 is
reported, the PTRS time domain density is determined according to a
certain table.
[0209] In a case of PUSCH transmission (at least including a case
of UCI on PUSCH without data), an MCS index within the range of 0
to 27 may be reported or an MCS index within the range of 28 to 31
may be reported in retransmission.
[0210] The method of determining PTRS (for example, time domain
density) in retransmission is not defined.
<Suggestion 1>
[0211] In retransmission, in other words, when the value of the new
data indicator field in reported DCI is different from the value of
the same field in the previous DCI (for example, the value of the
new data indicator field in the reported DCI is changed from 0 to 1
or 1 to 0), as well as, the MCS index within the range of 0 to 27
is reported, the UE determines the time domain density of PTRS
according to the reported MCS index and a certain table.
[0212] When an MCS index within the range of 28 to 31 is reported,
any of following suggestions 1-1, 1-2, 1-3 is adopted.
Suggestion 1-1
[0213] The time domain density of PTRS used in initial transmission
is used.
Suggestion 1-2
[0214] Time domain density is determined according to a certain
conversion method, based on the time domain density of PTRS used in
initial transmission.
<<Suggestion 1-2-1>>
[0215] A row up the row used in the initial transmission, in a
certain table, is used. This lowers the density and the coding
rate, thereby improving characteristics.
<<Suggestion 1-2-2>>
[0216] A row down the row used in the initial transmission, in a
certain table, is used. This increases the density and facilitates
gaining of phase noise correction effects more effectively, thereby
improving characteristics.
Suggestion 1-3
[0217] The time domain density of PTRS is determined according to
an MCS index reported in retransmission, a certain table, and a
certain conversion formula (refer to FIGS. 5 to 7).
[0218] For example, the time domain density of PTRS in
retransmission is determined according to a modulation order
reported by MCS index within the range of 28 to 31 and an MCS index
threshold reported in a higher layer. As an example, as shown in
FIG. 6 or 7, the time domain density of PTRS in retransmission is
determined according to the modulation order corresponding to the
MCS index within the range of 28 to 31 and the MCS index threshold
reported in a higher layer.
<Suggestion 2>
[0219] The time domain density of PTRS may be determined using
above-described suggestion 1-3 when an MCS index within the range
of 28 to 31 is reported in initial transmission. For example, the
time domain density of PTRS is determined by the reported MCS
index, a certain table, and a certain conversion formula.
<Suggestion 3>
[0220] The value of PTRS-UL configuration (for example,
PTRS-UplinkConfig) reported from a base station to the UE may use 0
to 27. In this way, unnecessary RRC bit can be removed compared
with a case of configuring the PTRS-UplinkConfig within the range
of 0 to 29. The PTRS-UL configuration may be transmitted using a
higher layer (for example, RRC signaling or the like).
[0221] In view of above, the following structures are
suggested.
[Structure 1]
[0222] A user terminal including:
[0223] a transmitting section that transmits a phase tracking
reference signal (PTRS) for an uplink control channel that is used
for transmission of uplink control information without data (UL-SCH
or transport channel); and
[0224] a control section that controls a determination method of
time domain density of PTRS, based on whether a modulation and
coding scheme (MCS) index reported in downlink control information
is included in a first range or a second range.
[Structure 2]
[0225] A radio communication method including: a step of
transmitting a phase tracking reference signal (PTRS) for an uplink
control channel that is used for transmission of uplink control
information without data; and a step of controlling a determination
method of time domain density of PTRS, based on whether a
modulation and coding scheme (MCS) index reported in downlink
control information is included in a first range or a second
range.
[0226] Now, although the invention according to the present
disclosure has been described in detail above, it should be obvious
to a person skilled in the art that the invention according to the
present disclosure is by no means limited to the embodiments
described in the present disclosure. The invention according to the
present disclosure can be implemented with various corrections and
in various modifications, without departing from the spirit and
scope of the invention defined by the recitations of claims.
Consequently, the description of the present disclosure is provided
only for the purpose of explaining examples, and should by no means
be construed to limit the invention according to the present
disclosure in any way.
[0227] The present application is based on Japanese Patent
Application No. 2018-110697 filed on May 23, 2018. The entire
contents of which is incorporated herein.
* * * * *