U.S. patent application number 17/565353 was filed with the patent office on 2022-04-21 for method and apparatus for data modulation and coding for new radio.
This patent application is currently assigned to KT CORPORATION. The applicant listed for this patent is KT CORPORATION. Invention is credited to Kyujin PARK.
Application Number | 20220123855 17/565353 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-21 |
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United States Patent
Application |
20220123855 |
Kind Code |
A1 |
PARK; Kyujin |
April 21, 2022 |
METHOD AND APPARATUS FOR DATA MODULATION AND CODING FOR NEW
RADIO
Abstract
Provided is a method of transmitting scheduling control
information on a physical uplink shared channel by a base station.
The method includes transmitting control information indicating a
specific modulation and coding scheme (MCS) index corresponding to
modulation and coding scheme (MCS) information to be applied to the
physical uplink shared channel through a physical downlink control
channel, and receiving the physical uplink shared channel modulated
based on specific MCS information determined using one of two or
more MCS tables containing the specific MCS index and modulation
order information corresponding to at least the MCS index.
Inventors: |
PARK; Kyujin; (Seongnam-si,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KT CORPORATION |
Seongnam-si |
|
KR |
|
|
Assignee: |
KT CORPORATION
Seongnam-si
KR
|
Appl. No.: |
17/565353 |
Filed: |
December 29, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16241086 |
Jan 7, 2019 |
11258532 |
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17565353 |
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International
Class: |
H04L 1/00 20060101
H04L001/00; H04W 76/11 20060101 H04W076/11; H04W 72/04 20060101
H04W072/04; H04W 4/70 20060101 H04W004/70 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2018 |
KR |
10-2018-0004091 |
May 24, 2018 |
KR |
10-2018-0058965 |
Oct 31, 2018 |
KR |
10-2018-0132306 |
Claims
1-20. (canceled)
21. A method of receiving control information for a physical data
channel by a wireless device, the method comprising: receiving,
through a physical downlink control channel, the control
information indicating a specific modulation and coding scheme
(MCS) index corresponding to specific MCS information for the
physical data channel; and determining the specific MCS information
used for the physical data channel using the specific MCS index and
one MCS table from a plurality of MCS tables, wherein the one MCS
table comprises modulation order information and a target code rate
corresponding to the specific MCS index, wherein the one MCS table
is configured based on a lower modulation order, which is lower
than 256 quadrature amplitude modulation (QAM), and wherein the one
MCS table is associated with a specific RNTI for both a physical
downlink shared channel and a physical uplink shared channel
performing a code block group based retransmission.
22. The method of claim 21, wherein the specific RNTI is an
MCS-C(Cell)-radio network temporary identifier (RNTI).
23. The method of claim 21, wherein the specific RNTI is allocated
by a base station through a higher layer signaling.
24. The method of claim 21, wherein the one MCS table is associated
with the reception of the physical downlink control channel in a
certain search space.
25. The method of claim 24, wherein the certain search space is a
user equipment (UE)-specific search space.
26. The method of claim 21, wherein a format of the physical
downlink control channel indicating the specific MCS index for the
physical downlink shared channel is different from a format of the
physical downlink control channel indicating the specific MCS index
for the physical uplink shared channel.
27. A wireless device comprising: a receiver configured to receive
control information indicating a specific modulation and coding
scheme (MCS) index corresponding to specific MCS information for a
physical data channel through a physical downlink control channel;
and a controller configured to determine the specific MCS
information used for the physical data channel using the specific
MCS index and one MCS table from a plurality of MCS tables, wherein
the one MCS table comprises modulation order information and a
target code rate corresponding to the specific MCS index, wherein,
based on the determined specific MCS information, the physical data
channel is transmitted or received, wherein the one MCS table is
configured based on a lower modulation order, which is lower than
256 quadrature amplitude modulation (QAM), and wherein the one MCS
table is associated with a specific RNTI for both a physical
downlink shared channel and a physical uplink shared channel
performing a code block group based retransmission.
28. The wireless device of claim 27, wherein the specific RNTI is
an MCS-C (Cell)-radio network temporary identifier (RNTI).
29. The wireless device of claim 27, wherein the specific RNTI is
allocated by a base station through a higher layer signaling.
30. The wireless device of claim 27, wherein the one MCS table is
associated with the reception of the physical downlink control
channel in a certain search space.
31. The wireless device of claim 30, wherein the certain search
space is a user equipment (UE)-specific search space.
32. The wireless device of claim 27, wherein a format of the
physical downlink control channel indicating the specific MCS index
for the physical downlink shared channel is different from a format
of the physical downlink control channel indicating the specific
MCS index for the physical uplink shared channel.
33. A method of transmitting control information for a physical
data channel by a base station, the method comprising: determining
specific modulation and coding scheme (MCS) information used for
the physical data channel; and after determining the specific MCS
information, transmitting, through a physical downlink control
channel, the control information indicating a specific modulation
and coding scheme (MCS) index corresponding to specific MCS
information for the physical data channel, wherein the specific MCS
information is determined based on one MCS table from a plurality
of MCS tables, wherein the one MCS table comprises modulation order
information and a target code rate corresponding to the specific
MCS index, wherein, based on the determined specific MCS
information, the physical data channel is transmitted or received,
wherein the one MCS table is configured based on a lower modulation
order, which is lower than 256 quadrature amplitude modulation
(QAM), and wherein the one MCS table is associated with a specific
RNTI for both a physical downlink shared channel and a physical
uplink shared channel performing a code block group based
retransmission.
34. The method of claim 33, wherein the specific RNTI is an
MCS-C(Cell)-radio network temporary identifier (RNTI).
35. The method of claim 33, wherein the specific RNTI is allocated
through a higher layer signaling.
36. The method of claim 33, wherein the one MCS table is associated
with the transmission of the physical downlink control channel in a
certain search space.
37. The method of claim 36, wherein the certain search space is a
user equipment (UE)-specific search space.
38. The method of claim 33, wherein a format of the physical
downlink control channel indicating the specific MCS index for the
physical downlink shared channel is different from a format of the
physical downlink control channel indicating the specific MCS index
for the physical uplink shared channel.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Korean Patent
Applications No. 10-2018-004091, filed on Jan. 11, 2018, No.
10-2018-0058965, filed on May 24, 2018, & No. 10-2018-0132306,
filed on Oct. 31, 2018 which are hereby incorporated by reference
for all purposes as if fully set forth herein.
BACKGROUND OF THE DISCLOSURE
Technical Field
[0002] The present disclosure relates to methods and apparatuses
for transmitting and/or receiving control information through a
physical data channel in a next-generation/5G radio access network
(hereinafter, referred to as a new radio (NR)).
[0003] More specifically, the present disclosure proposes methods
of data modulation and coding for satisfying requirements of
reliability for ultra reliable and low latency communications
(URLLC) data.
Background Art
[0004] Recently, the 3rd generation partnership project (3GPP) has
approved the "Study on New Radio Access Technology", which is a
study item for research on next-generation/5G radio access
technology. On the basis of the Study on New Radio Access
Technology, Radio Access Network Working Group 1 (RAN WG1) has been
discussing frame structures, channel coding and modulation,
waveforms, multiple access methods, and the like for the new radio
(NR). The NR is required to be designed not only to provide an
improved data transmission rate as compared with the long term
evolution (LTE)/LTE-Advanced, but also to meet various requirements
in detailed and specific usage scenarios.
[0005] An enhanced mobile broadband (eMBB), massive machine-type
communication (mMTC), and ultra reliable and low latency
communication (URLLC) are proposed as representative usage
scenarios of the NR. In order to meet the requirements of the
individual scenarios, it is required to design frame structures to
be more flexible, compared with the LTE/LTE-Advanced.
[0006] Particularly, there is an increasing need for a specific and
efficient method of defining a separate modulation and coding
scheme (MCS) table for each target block error rate (BLER) in the
NR.
SUMMARY
[0007] To address such issues, at least one object of the present
disclosure is to provide methods and apparatuses for defining a
separate MCS table for each target BLER in the NR.
[0008] In accordance with an aspect of the present disclosure, a
method of a base station is provided for transmitting scheduling
control information on a physical uplink shared channel.
[0009] The method of the base station includes transmitting control
information indicating a specific modulation and coding scheme
(MCS) index corresponding to modulation and coding scheme (MCS)
information to be applied to a physical uplink shared channel
through a physical downlink control channel, and determining
specific MCS information used for the physical uplink shared
channel using the specific MCS index and one of two or more MCS
tables containing modulation order information and target code rate
corresponding to at least the specific MCS index.
[0010] In accordance with another aspect of the present disclosure,
a method of a user equipment is provided for receiving scheduling
control information on a physical data channel.
[0011] The method of the user equipment includes receiving control
information indicating a specific modulation and coding scheme
(MCS) index corresponding to modulation and coding scheme (MCS)
information to be applied to a physical data channel through a
physical downlink control channel, and determining specific MCS
information used for the physical data channel using the specific
MCS index and one of two or more MCS tables containing modulation
order information and target code rate corresponding to the
specific MCS index.
[0012] In accordance with another aspect of the present disclosure,
a base station is provided for transmitting scheduling control
information on a physical uplink shared channel.
[0013] The base station includes a transmitter configured to
transmit control information indicating a specific modulation and
coding scheme (MCS) index corresponding to modulation and coding
scheme (MCS) information to be applied to a physical uplink shared
channel through a physical downlink control channel, and a receiver
configured to receive the physical uplink shared channel modulated
based on specific MCS information determined using the specific MCS
index and one of two or more MCS tables containing modulation order
information and target code rate corresponding to the specific MCS
index.
[0014] In accordance with another aspect of the present disclosure,
a user equipment is provided for receiving scheduling control
information on a physical data channel.
[0015] The user equipment includes a receiver configured to receive
control information indicating a specific modulation and coding
scheme (MCS) index corresponding to modulation and coding scheme
(MCS) information to be applied to a physical data channel through
a physical downlink control channel, and a controller configured to
determine specific MCS information used for the physical data
channel using the specific MCS index and one of two or more MCS
tables containing modulation order information and target code rate
corresponding to the specific MCS index.
[0016] In accordance with embodiments of the present disclosure, it
is possible to define a separate MCS table for each target BLER in
the NR.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a diagram schematically illustrating a structure
of a NR wireless communication system.
[0018] FIG. 2 is a diagram illustrating a frame structure of a NR
system.
[0019] FIG. 3 is a diagram illustrating a resource grid supported
by radio access technology.
[0020] FIG. 4 is a diagram illustrating a bandwidth part supported
by radio access technology.
[0021] FIG. 5 is a diagram illustrating an exemplary
synchronization signal block in radio access technology.
[0022] FIG. 6 is a diagram illustrating a random access procedure
in radio access technology.
[0023] FIG. 7 is a diagram illustrating control resource sets
(CORESETs).
[0024] FIG. 8 is a diagram illustrating a comparison between a
subslot and a slot.
[0025] FIG. 9 is a diagram illustrating that a user equipment using
a RLLC service preempts a resource allocated to a user equipment
using an eMBB service.
[0026] FIG. 10 is a diagram illustrating a transmission block
configuration for supporting code block group based
retransmission.
[0027] FIG. 11 is a flow chart illustrating a method of a base
station for transmitting control information on a physical uplink
shared channel according to an embodiment of the present
disclosure.
[0028] FIG. 12 is a flow chart illustrating a method of a user
equipment for receiving control information on a physical data
channel according to an embodiment of the present disclosure.
[0029] FIG. 13 is a block diagram illustrating a base station
according to an embodiment of the present disclosure.
[0030] FIG. 14 is a block diagram illustrating a user equipment
according to an embodiment of the present disclosure.
DETAILED DESCRIPTION
[0031] Hereinafter, embodiments of the present disclosure will be
described in detail with reference to the accompanying drawings. In
denoting elements of the drawings by reference numerals, the same
elements will be referenced by the same reference numerals although
the elements are illustrated in different drawings. In the
following description of the present disclosure, a detailed
description of known functions and configurations incorporated
herein will be omitted when it is determined that the description
may make the subject matter of the present disclosure rather
unclear.
[0032] Terms, such as first, second, A, B, (a), or (b) may be used
herein to describe elements of the disclosure. Each of the terms is
not used to define essence, order, sequence, or number of an
element, but is used merely to distinguish the corresponding
element from another element. When it is mentioned that an element
is "connected" or "coupled" to another element, it should be
interpreted that another element may be "interposed" between the
elements or the elements may be "connected" or "coupled" to each
other via another element as well as that one element is directly
connected or coupled to another element.
[0033] In addition, terms and technical names used herein are for
the purpose of describing specific embodiments, and technical
spirit of the present disclosure is not limited to the
corresponding terms. Unless defined otherwise, the terms described
below may be construed in a manner normally understood by any
person skilled in the art to which the present disclosure pertains.
In a case where a corresponding term is a misleading technical term
that does not precisely embody the technical spirit of the present
disclosure, it should be understood that the term is replaced by a
technical term that can be correctly understood by any person
skilled in the art. Further, the terms used in the present
disclosure should be construed as according to definitions in
dictionaries or context, and should not be construed as being
excessively reduced in meaning.
[0034] In the present disclosure, the wireless communication
systems refer to systems for providing various communication
services using radio resources, such as a voice service, a data
packet service, etc., and may include a user equipment, a base
station, and a core network.
[0035] Preferred embodiments described below may be applied to
wireless communication systems using various radio access
technologies. For example, embodiments of the present disclosure
may be applied to various multiple access techniques, such as code
division multiple access (CDMA), frequency division multiple access
(FDMA), time division multiple access (TDMA), orthogonal frequency
division multiple access (OFDMA), singlecarrier frequency division
multiple access (SC-FDMA), or the like. The CDMA may be implemented
with radio technologies, such as universal terrestrial radio access
(UTRA) or CDMA2000. The TDMA may be implemented with radio
technologies, such as global system for mobile communications
(GSM), general packet radio service (GPRS), enhanced datarates for
GSM evolution (EDGE). The OFDMA may be implemented with radio
technologies, such as institute of electrical and electronics
engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20,
evolved UTRA (E-UTRA), or the like. The IEEE 802.16m is an
evolution of IEEE 802.16e and provides backward compatibility with
systems based on IEEE 802.16e. The UTRA is a part of the universal
mobile telecommunications system (UMTS). 3rd generation partnership
project (3GPP) long term evolution (LTE) is a part of E-UMTS
(evolved UMTS) using evolved-UMTS terrestrial radio access
(E-UTRA), and uses the OFDMA in downlink and the SC-FDMA in uplink.
As described above, embodiments of the present disclosure may be
applied to radio access technologies that are currently being
launched or commercialized, or that are being developed or
developed in the future.
[0036] Meanwhile, in the present disclosure, a user equipment is
defined as a generic term meaning a device including a wireless
communication module performing communications with a base station
in a wireless communication system. The user equipment shall be
construed as including, but not limited to, all of devices, such
as, as well as a user equipment (UE) supporting wideband code
division multiple access (WCDMA), LTE, high speed packet access
(HSPA), international mobile telecommunications (IMT)-2020 (5G or
new radio), or the like, a mobile station (MS) supporting the GSM,
a user terminal (UT), a subscriber station (SS), a wireless device,
or the like. In addition, the UE may be a portable device such as a
smart phone according to a type of usage, and may denote a vehicle,
a device including a wireless communication module in the vehicle,
or the like, in a V2X communication system. In addition, in the
case of a machine type communication (MTC) system, the UE may
denote a MTC terminal, an M2M terminal, or the like, on which a
communication module enabling machine type communication to be
performed is mounted.
[0037] In the present disclosure, a base station or a cell
generally refers to a station communicating with the UE. The base
station or cell is defined as a generic term including, but not
limited to, all of various coverage areas, such as a Node-B, an
evolved Node-B (eNB), a gNode-B (gNB), a low power node (LPN), a
sector, a site, various types of antennas, a base transceiver
system (BTS), an access point, a point (e.g., a transmitting point,
a receiving point, or a transceiving point), a relay node, a
megacell, a macrocell, a microcell, a picocell, a femtocell, a
remote radio head (RRH), a radio unit (RU), a small cell, or the
like.
[0038] The various cells described above is controlled by a base
station, therefore the base station may be classified into two
categories. 1) The base station may be referred to an apparatus
that provides a megacell, a macrocell, a microcell, a picocell, a
femtocell, and a small cell, in association with a radio area, or
2) the base station may be referred to a radio area itself. In case
of 1) the base station may be referred to all apparatuses providing
any radio area i) by being controlled by the same entity or ii) by
cooperating with one another. A point, a transmission/reception
point, a transmission point, a reception point, and the like may be
examples of the base station according to methods of configuring
the radio area. In case of 2) the base station may be a radio area
itself for enabling a UE or a base station for receiving a signal
from or transmitting a signal to another UE or a neighboring base
station perspective.
[0039] In the present disclosure, the cell may refer to a coverage
of a signal transmitted from a transmission/reception point, a
component carrier having the coverage of a signal transmitted from
a transmission point or a transmission/reception point, or a
transmission/reception point itself.
[0040] Uplink (UL) refers to data transmission and reception from a
UE to a base station, and downlink (DL) refers to data transmission
and reception from a base station to a UE. The DL may denote
communication or a communication path from multiple
transmission/reception points to a UE, and the UL may denote
communication or a communication path from the UE to the multiple
transmission/reception points. At this time, in the DL, a
transmitter may be a part of multiple transmission/reception
points, and a receiver may be a part of a UE. In the UL, a
transmitter may be a part of a UE and a receiver may be a part of
multiple transmission/reception points.
[0041] The UL and the DL i) transmit/receive control information
through one or more control channels, such as a physical DL control
channel (PDCCH), a physical UL control channel (PUCCH), and the
like and ii) transmit/receive data through one or more data
channels, such as a physical DL shared channel (PDSCH), a physical
UL shared channel (PUSCH), and the like. Hereinafter, the
transmission/reception of a signal through the PUCCH, the PUSCH,
the PDCCH, or the PDSCH, may be described as the
transmission/reception of the PUCCH, the PUSCH, the PDCCH, or the
PDSCH.
[0042] Hereinafter, to describe clearly embodiments of the present
disclosure, description will be given based on the 3GPP
LTE/LTE-A/NR (New RAT) communication systems, but is not limited
thereto.
[0043] After 4th-generation (4G) communication technology has been
developed, studies on 5th-generation (5G) communication technology
are in progress in the 3GPP, in order to meet requirements for next
generation radio access technology under the ITU-R. Specifically,
in the 3GPP, studies on a new NR communication technology are in
progress independent of 4G communication technology and LTE-A pro
having improved LTE-Advanced technology according to requirements
of the ITU-R to reach 5G communication technology. It is assumed
that both the LTE-A pro and the NR will be introduced into 5G
communication technology, for convenience of description,
embodiments of the present disclosure will be described mainly with
reference to the NR.
[0044] Various operation scenarios of the NR are defined by adding
scenarios for a satellite, a vehicle, a new vertical, and the like,
in typical 4G LTE scenarios. In terms of services, the NR supports
an enhanced mobile broadband (eMBB) scenario, a massive machine
communication (MMTC) scenario in which i) the density of UEs is
high, ii) corresponding deployment is performed over a wide range,
and iii) low data rate and asynchronous access are required, and an
Ultra Reliability and Low Latency (URLLC) scenario in which high
responsiveness and reliability are required and high-speed mobility
can be supported.
[0045] To satisfy such scenarios, the NR specifies wireless
communication systems to which at least one of a new waveform and
frame structure technique, a low latency technique, a
millimeter-wave (mmWave) support technique and a forward compatible
providing technique is applied. In particular, in order to provide
forward compatibility, various technological changes in terms of
flexibility have been introduced into NR systems. Main technical
features of the present disclosure are described below with
reference to the drawings.
[0046] <General NR System>
[0047] FIG. 1 is a diagram schematically illustrating a structure
of a NR system.
[0048] Referring to FIG. 1, the NR system is divided into a 5G Core
Network (5GC) and an NR-RAN part. The NG-RAN includes a gNB and an
ng-eNB, which provide user plane (SDAP/PDCP/RLC/MAC/PHY) and
control plane (RRC) protocol terminations toward a user equipment
(UE). Interconnection between gNBs or between the gNB and the
ng-eNB is performed through a XNA interface. Each of the gNB and
the ng-eNB is connected to the 5GC through an NG interface. The 5GC
may include an access and mobility management function (AMF)
responsible for a control plane, such as UE access, mobility
control function, etc., and a user plane function (UPF) responsible
for a control function for user data. The NR supports both a
frequency range of 6 GHz or lower (FR1, Frequency Range 1) and a
frequency range of 6 GHz or higher (FR2, Frequency Range 2).
[0049] The gNB denotes a base station providing NR user plane and
control plane protocol terminations toward a UE, and the ng-eNB
denotes a base station providing E-UTRA user plane and control
plane protocol terminations toward a UE. In the present disclosure,
the base station should be understood as meaning including both the
gNB and the ng-eNB and may be used as meaning of the gNB or the
ng-eNB, if necessary.
[0050] <NR Waveform, Numerology and Frame Structure>
[0051] In the NR, a cyclic prefix (CP)-OFDM waveform using a cyclic
prefix is used for downlink transmission, and a CP-OFDM or a
Discrete Fourier Transform-spread (DFT-s)-OFDM is used for uplink
transmission. The OFDM technique is considered more attractive
technique in combining with multiple input multiple output (MIMO)
and has the advantage capable of using a low complexity receiver
with high frequency efficiency.
[0052] Meanwhile, in the NR, requirements for data rate, latency,
coverage, etc. are different for each of the three scenarios
described above. Therefore, it is necessary to efficiently satisfy
the requirements for each scenario through frequency bands
establishing an NR system. To do this, a technique has been
proposed for efficiently multiplexing a plurality of
numerology-based radio resources different from one another.
[0053] Specifically, NR transmission numerology is determined based
on a subcarrier spacing and a cyclic prefix (CP), and the .mu.value
has an exponential value of 2 based on 15 kHz and exponentially
changed, as shown in Table 1 below.
TABLE-US-00001 TABLE 1 Subcarrier Supported Supported .mu. spacing
Cyclic prefix for data for synch 0 15 Normal Yes Yes 1 30 Normal
Yes Yes 2 60 Normal, Extended Yes No 3 120 Normal Yes Yes 4 240
Normal No Yes
[0054] As shown in Table 1 above, the NR numerology may be
classified into five types according to subcarrier spacings. Unlike
the NR, in LTE that is one of 4G communication techniques, a
subcarrier spacing is fixed with 15 kHz. Specifically, in the NR,
subcarrier spacings used for data transmission are 15, 30, 60, and
120 kHz, and subcarrier spacings used for synchronous signal
transmission are 15, 30, 12, and 240 kHz. Also, an extended CP is
applied only to the 60 kHz subcarrier spacing. Meanwhile, as a
frame structure of the NR, a frame is defined as a length of 10 ms
composed of 10 subframes having the same length of 1 ms. One frame
may be divided into 5 ms half frames, and each half frame includes
5 subframes. In the case of the 15 kHz subcarrier spacing, one
subframe is composed of one slot and each slot is composed of 14
OFDM symbols. FIG. 2 is a diagram illustrating a frame structure of
a NR system.
[0055] Referring to FIG. 2, the slot is fixedly made up of 14 OFDM
symbols in the case of normal CP, but the length of the slot may
vary according to subcarrier spacings. For example, in the case of
a numerology with the 15 kHz subcarrier spacing, the slot has 1 ms
length identical to the subframe. In the case of a numerology with
the 30 kHz subcarrier spacing, the slot is composed of 14 OFDM
symbols and has 0.5 ms length. Therefore, two slots may form one
subframe. That is, the subframe and the frame are defined with a
fixed time length, and the slot is defined by the number of
symbols. Therefore, the time length may vary according to
subcarrier spacings.
[0056] Meanwhile, NR defines a slot as a basic unit of scheduling
and also introduces a minislot (or a subslot or a non-slot based
schedule) to reduce transmission delay in the radio section. When a
wide subcarrier spacing is used, the transmission delay in the
radio section may be reduced because the length of one slot is
shortened in inverse proportion. The minislot (or subslot) is for
efficient support for URLLC scenarios and may be scheduled on the
basis of 2, 4, or 7 symbols.
[0057] Also, unlike the LTE, the NR defines uplink and downlink
resource allocations on a symbol basis within one slot. In order to
reduce HARQ latency, a slot structure capable of directly
transmitting HARQ ACK/NACK in a transmission slot is defined, and
this slot structure is referred to as a self-contained structure
for description.
[0058] The NR has been designed to support a total of 256 slot
formats, of which 62 slot formats are used in Rel-15. In addition,
a common frame structure including an FDD, or a TDD frame is
supported through various slot combinations. For example, the NR
supports i) a slot structure in which all symbols of a slot are
configured in downlink, ii) a slot structure in which all symbols
of a slot are configured in uplink, and iii) a slot structure in
which downlink symbols and uplink symbols are combined. In
addition, the NR supports that data transmission is scheduled with
data distributed in one or more slots. Accordingly, a base station
may inform a UE whether a corresponding slot is a downlink slot, an
uplink slot, or a flexible slot, using a slot format indicator
(SFI). The base station may indicate a slot format i) by indicating
an index of a table configured through UE-specific RRC signaling,
using the SFI, ii) dynamically through downlink control information
(DCI), or iii) statically or quasi-statically through RRC.
[0059] <NR Physical Resources>
[0060] An antenna port, a resource grid, a resource element, a
resource block, a bandwidth part, or the like is considered for a
physical resource in the NR.
[0061] The antenna port is defined such that a channel for carrying
a symbol on an antenna port may be inferred from a channel for
carrying another symbol on the same antenna port. If a large-scale
property of a channel carrying a symbol on one antenna port may be
inferred from a channel carrying a symbol on another antenna port,
the two antenna ports may be in a quasi co-located or quasi
co-location (QC/QCL) relationship. Here, the large-scale property
includes at least one of a delay spread, a Doppler spread, a
frequency shift, an average received power, and a received
timing.
[0062] FIG. 3 is a diagram illustrating a resource grid supported
by radio access technology.
[0063] Referring to FIG. 3, since the NR supports a plurality of
numerologies in the same carrier, a resource grid may be configured
according to each numerology. In addition, the resource grid may be
configured depending on an antenna port, a subcarrier spacing, and
a transmission direction.
[0064] A resource block is composed of 12 subcarriers and is
defined only in the frequency domain. In addition, a resource
element is composed of one OFDM symbol and one subcarrier.
Therefore, as shown in FIG. 3, the size of one resource block may
vary according to the subcarrier spacings. In addition, the NR
defines "Point A" that serves as a common reference point for
resource block grids, a common resource block, and a virtual
resource block.
[0065] FIG. 4 is a diagram illustrating a bandwidth part supported
by radio access technology.
[0066] In the NR, the maximum carrier bandwidth is set from 50 MHz
to 400 MHz according to subcarrier spacings, unlike the LTE in
which carrier bandwidth is fixed at 20 MHz. Therefore, it is not
assumed that all UEs use all of these carrier bandwidths. As a
result, as shown in FIG. 4, in the NR, a bandwidth may be
configured within a carrier bandwidth part in order for a UE to
use. In addition, the bandwidth part i) is associated with one
numerology, ii) is composed of a contiguous subset of the common
resource blocks and iii) can be activated dynamically over time. In
the UE, up to four bandwidth parts are configured in each of uplink
and downlink, and data is transmitted/received using an activated
bandwidth part at a given time.
[0067] In the case of a paired spectrum, the uplink and downlink
bandwidth parts are configured independently. In the case of an
unpaired spectrum, the downlink and uplink bandwidth parts are
configured in pairs to enable a center frequency to be shared to
prevent unnecessary frequency re-tuning between downlink and uplink
operations.
[0068] <NR Initial Access>
[0069] In the NR, a UE performs cell search and random access
procedures to access a base station and perform communication.
[0070] The cell search is a procedure of i) synchronizing a UE with
a cell of a corresponding base station using a synchronization
signal block (SSB) transmitted from the base station, ii) acquiring
a physical layer cell ID, and iii) acquiring system
information.
[0071] FIG. 5 is a diagram illustrating an exemplary
synchronization signal block in radio access technology.
[0072] Referring to FIG. 5, the SSB includes i) a primary
synchronization signal (PSS) and a secondary synchronization signal
(SSS), each of which occupies one symbol and 127 subcarriers, and
ii) a PBCH configured on three OFDM symbols and 240
subcarriers.
[0073] The UE monitors the SSB in the time and frequency domain and
receives the SSB.
[0074] The SSB may be transmitted up to 64 times for 5 ms. A
plurality of SSBs are transmitted in different transmission beams
within 5 ms duration, and the UE detects the SSBs, assuming that
the SSBs are transmitted every 20 ms period based on a specific one
beam used for transmission. The higher the frequency band is, the
greater the number of beams that may be used for SSB transmission
within 5 ms duration can increase. For example, the SSBs may be
transmitted using i) up to four different beams in a frequency band
of 3 GHz or lower, ii) up to 8 different beams in a frequency band
of 3 to 6 GHz, and iii) up to 64 different beams in a frequency
band of 6 GHz or higher.
[0075] Two SSBs are included in one slot, and the start symbol and
the number of repetitions in a slot are determined according to
subcarrier spacings as described below.
[0076] Meanwhile, the SSB is not transmitted at a center frequency
of a carrier bandwidth unlike the SS of the LTE. That is, the SSB
may be transmitted on a frequency that is not the center of a
system band, and a plurality of SSBs may be transmitted in the
frequency domain in a case where wideband operation is supported.
Thus, the UE monitors a SSB using a synchronization raster, which
is a candidate frequency position for monitoring the SSB. A carrier
raster and the synchronous raster, which are center frequency
position information of a channel for initial access, are newly
defined in the NR. The synchronous raster is configured with a
wider frequency interval than the carrier raster, and thus, may
support that a UE rapidly searches the SSB.
[0077] The UE may acquire a master information block (MIB) through
the PBCH of the SSB. The MIB includes minimum information for
receiving remaining minimum system information (RMSI) by the UE
broadcast from the network. The PBCH may include information on the
position of the first DM-RS symbol in the time domain, information
for monitoring SIB1 by the UE (for example, SIB1 numerology
information, SIB1 CORESET related information, search space
information, PDCCH related parameter information, etc.), offset
information between a common resource block and a SSB (the absolute
position of the SSB in a carrier is transmitted via the SIB1), and
the like. Here, the SIB1 numerology information is equally applied
to messages 2 and 4 of a random access procedure for accessing a
base station after the UE has completed the cell search
procedure.
[0078] The RMSI means the system information block 1 (SIB1), and
the SIB1 is broadcast periodically (ex, 160 ms) in a corresponding
cell. The SIB1 includes information necessary for the UE to perform
an initial random access procedure, and the SIB1 is periodically
transmitted through the PDSCH. In order for the UE to receive the
SIB1, the UE is required to receive numerology information used for
SIB1 transmission and control resource set (CORESET) information
used for SIB1 scheduling, through the PBCH. The UE checks
scheduling information for the SIB1 using a SI-RNTI in the CORESET,
and acquires the SIB1 on the PDSCH according to the scheduling
information. Remaining SIB s other than the SIB1 may be transmitted
periodically or may be transmitted according to the request of a
UE.
[0079] FIG. 6 is a diagram illustrating a random access procedure
in radio access technology.
[0080] Referring to FIG. 6, when cell search is completed, a UE
transmits a random access preamble for random access to a base
station. The random access preamble is transmitted through PRACH.
Specifically, the random access preamble is transmitted to the base
station through PRACH, which is made up of consecutive radio
resources in a specific slot repeated periodically. Generally, a
contention-based random access procedure is performed when a UE
initially accesses a cell, and a non-contention based random access
procedure is performed when random access is performed for beam
failure recovery (BFR).
[0081] The UE receives a random access response to the transmitted
random access preamble. The random access response may include a
random access preamble identifier (ID), an UL grant (uplink radio
resource), a temporary cell-radio network temporary identifier
(temporary C-RNTI), and a time alignment command (TAC). Since one
random access response may include random access response
information for one or more UEs, the random access preamble
identifier may be included to inform which UE the included UL
grant, temporary C-RNTI and TAC are valid to. The random access
preamble identifier may be an identifier of a random access
preamble received by the base station. The TAC may be included as
information for adjusting uplink synchronization by a UE. The
random access response may be indicated by a random access
identifier on the PDCCH, i.e., a random access-radio network
temporary identifier (RA-RNTI).
[0082] When receiving the valid random access response, the UE
processes information included in the random access response and
performs scheduled transmission to the base station. For example,
the UE applies the TAC and stores the temporary C-RNTI. In
addition, using the UL grant, the UE transmits data stored in a
buffer or newly generated data to the base station. In this case,
information for identifying the UE should be included.
[0083] The UE receives a downlink message for contention
resolution.
[0084] <NR CORESET>
[0085] A downlink control channel in the NR is transmitted on a
control resource set (CORESET) having a length of 1 to 3 symbols
and transmits up/down scheduling information, slot format index
(SFI) information, transmit power control information, and the
like.
[0086] Thus, in the NR, in order to secure the flexibility of the
system, the CORESET is introduced. The control resource set
(CORESET) refers to a time-frequency resource for a downlink
control signal. The UE may decode a control channel candidate using
one or more search spaces in a CORESET time-frequency resource.
Quasi CoLocation (QCL) assumption is established for each CORESET,
which is used for the purpose of informing characteristics for
analogue beam directions besides characteristics assumed by typical
QCL, such as delayed spread, Doppler spread, Doppler shift, or
average delay.
[0087] FIG. 7 is a diagram illustrating CORESETs.
[0088] Referring to FIG. 7, a CORESET may be configured in various
forms within a carrier bandwidth in one slot. The CORESET may
include a maximum of 3 OFDM symbols in the time domain. In
addition, the CORESET is defined as a multiple of six resource
blocks up to the carrier bandwidth in the frequency domain.
[0089] The first CORESET is indicated through the MIB as a part of
an initial bandwidth part configuration to enable additional
configuration information and system information to be received
from the network. After establishing a connection with a base
station, a UE may receive and configure one or more pieces of
CORESET information through RRC signaling.
[0090] Hereinafter, the URLLC will be described.
[0091] Hereinafter, the URLLC service will be described in
detail.
[0092] The URLLC service is devised to meet requirements of the UE
for scenarios in which reliability of data transmission and latency
minimization are more important than data transmission rate, and
both LTE system and the NR will support the URLLC.
[0093] Examples of the scenarios in which the reliability of data
transmission and the latency minimization are important include a
scenario for an autonomous vehicle required to recognize changes
rapidly in an external situation such as an accident, a scenario
for warning the detection of dangerous material leakage within a
limited time, or the like.
[0094] As an example of the requirements related to the latency of
the URLLC service, end-to-end (E2E) latency is required to be
within 5 ms, and the latency of the user plane is required to be
within 0.5 ms. As an example of the requirements related to the
transmission reliability of the URLLC service, a block error rate
(BLER) is required to be 10-5 or less, and it is required to
support mobility for a UE moving at a high speed up to 500 km.
[0095] In order to satisfy the requirements for the URLLC service
in the next generation mobile communication system, it is necessary
for a resource used for data transmission/reception to be allocated
rapidly to a UE using the URLLC service. In addition, it is
necessary for a resource to be allocated to a UE using the URLLC
service with a higher priority than a UE using an eMBB service or
an mMTC service.
[0096] <NR Mini-Slot>
[0097] As described above, in the NR, one subframe is determined to
be 1 ms regardless of the subcarrier spacing (SCS). One slot is
composed of 14 OFDM symbols, and the number of slots forming one
subframe may be different according to subcarrier spacings.
[0098] Thus, considering that it varies depending on the subcarrier
spacings, in the NR, resources for data transmission/reception may
be normally scheduled on a per-slot basis. This scheduling scheme
is referred to as slot-based scheduling.
[0099] However, it is necessary for a UE using the URLLC service to
be allocated resources for data transmission/reception in a unit
smaller than the slot in order to satisfy a corresponding low
latency requirement. Thus, with a subslot smaller than the slot
defined, a technique for scheduling resources on a per-subslot
basis is introduced into the NR, and this scheduling scheme is
referred to as non-slot based scheduling.
[0100] The subslot may also be referred to as a mini-slot and may
composed of 2, 4, or 7 OFDM symbols, unlike the slot composed of 14
OFDM symbols. Accordingly, when resources are scheduled on a
per-subslot basis, a UE using the URLLC service may be allocated
resources for data transmission/reception more rapidly.
[0101] FIG. 8 is a diagram illustrating a comparison between a
subslot and a slot.
[0102] Referring to FIG. 8, one slot is composed of 14 OFDM
symbols, whereas a subslot (mini-slot) is composed of 2 or 4 OFDM
symbols. That is, when resources are scheduled on a per-subslot
basis, a plurality of UEs may be allocated resources within one
slot and then use them for data transmission/reception.
[0103] <Preemption>
[0104] Meanwhile, in order for a UE using the URLLC service to be
allocated a resource with a high priority, the next generation
mobile communication system provides a preemption technique that
allows the UE to use a resource already allocated to another UE
using the eMBB service or the mMTC service.
[0105] As described above, in order to support the URLLC service,
it is necessary to subdivide a unit for performing resource
scheduling in the time domain. As a result, a resource may be
allocated to a UE using the URLLC service on the basis of a
subslot, which is a time unit smaller than a slot.
[0106] On the contrary, it is preferable to define a unit for
performing resource scheduling for a UE using the eMBB service or
the mMTC service on the basis of a longer time compared with a UE
using the URLLC service. The longer scheduling time unit, the less
overhead that occurs in the process of controlling scheduling.
[0107] However, in the case of scheduling on the basis of such a
long time, it is necessary to consider a case where a UE using the
URLLC service is urgently required to be allocated a resource for
data transmission while a UE using the MMTC service or the eMBB
service allocated a resource on the basis of a long time is using
the resource. For example, URLLC traffic may occur during eMBB
transmission.
[0108] In this case, if a UE using the URLLC service is allocated a
resource after UEs using the eMBB service or the mMTC service have
used all allocated resources, there is a possibility of not
satisfying the latency requirement required by the URLLC
service.
[0109] As one way to solve this problem, it is possible to consider
a method of configuring scheduling in the time domain on a short
time basis for the e-MBB service and the mMTC service as well as
the URLLC service. However, configuring scheduling in the time
domain on a short time basis for all services for URLLC service
traffic that is intermittently occurring results in increasing
scheduling overhead as described above.
[0110] Therefore, in a case where a UE using the URLLC service
required to satisfy latency requirements is urgently required to be
allocated a resource, instead of being allocated a resource with
scheduling on the basis of time units different from one another in
the time domain for each service, it is possible for the UE using
the URLLC service to preempt and use a part of a resource(s)
allocated to a UE using the eMBB service or the mMTC service.
[0111] In a case where the UE using the URLLC service has preempted
the resource, when a UE that has been originally allocated the
resource receives information indicating that the preemption has
occurred, the UE is required not to use the resource any longer or
discard data transmitted through the resource.
[0112] That is, when a UE using the eMBB service or the mMTC
service is instructed that an allocated resource is preempted by
another UE using the URLLC service, the UE using the eMBB service
or the mMTC service is required to flush data for the corresponding
preempted resource area from the soft buffer.
[0113] FIG. 9 is a diagram illustrating that a UE using a RLLC
service preempts a resource allocated to a UE using an eMBB
service.
[0114] Referring to FIG. 9, a diagram (a) illustrates a case where
a preemption occurs when a numerology applied to the URLLC service
and a numerology applied to the eMBB service are different from
each other.
[0115] In the diagram (a) of FIG. 9, a UE using the URLLC service
selects and uses a 4th OFDM symbol from the left in the time domain
among resources allocated to a UE using the eMBB service, a 4th to
7th subcarrier resources from the bottom in the frequency
domain.
[0116] In this case, since the numerology for the URLLC service is
applied to resources preempted by the UE using the URLLC service,
an OFDM symbol length and a subcarrier spacing of the preempted
resources are different from a symbol length and a subcarrier
spacing of resources allocated to the UE using the eMBB
service.
[0117] A diagram (b) of FIG. 9 illustrates a case where preemption
occurs when a numerology applied to the URLLC service and a
numerology applied to the eMBB service are the same.
[0118] Similar to the diagram (a) of FIG. 9, in the diagram (b) of
FIG. 9, a UE using the URLLC service preempts and uses a 4th OFDM
symbol from the left in the time domain among resources allocated
to a UE using the eMBB service, a 4th to 7th subcarrier resources
from the bottom in the frequency domain.
[0119] In this case, since the same numerology is applied to the
resources preempted by the UE using the URLLC service, an OFDM
symbol length and a subcarrier spacing of the preempted resources
are identical to a symbol length and a subcarrier spacing of
resources allocated to the UE using the eMBB service.
[0120] <URLLC HARQ>
[0121] The NR supports flexible HARQ timing based on dynamic
downlink control information considering dynamic TDD operation. For
example, in a state where a plurality of PDCCH-to-PDSCH and
PDSCH-to-PUCCH time delay values are set for each UE through RRC
signaling, a specific delay value is indicated using downlink or
uplink scheduling information.
[0122] Meanwhile, in order to reduce latency in the URLLC service,
it is necessary to configure a retransmission unit smaller than the
LTE.
[0123] In the case of the LTE, when transmitting data, it is
determined whether data retransmission is performed on a
transmission block (or a transport block) (TB) basis.
[0124] Specifically, when a transmitting end transmits a
transmission block, a 24-bit CRC (Cyclic Redundancy Check) is
additionally inserted into the entire transmission block, and the
CRC is additionally inserted into each code block (CB) composing
the transmission block.
[0125] A receiving end that receives the transmission block
transmitted from the transmitting end performs a CRC check on the
CRC for the entire transmission block and the CRC for each code
block.
[0126] At this time, if the CRC check is successful for both the
CRC for the entire transmission block and the CRC for each code
block, the receiving end determines that there is no error in the
corresponding transmission block. On the other hand, if the CRC
check fails for either the CRC for the entire transmission block or
the CRC for each code block, the receiving end determines that
there is an error in the corresponding transmission block and
requests retransmission for the entire transmission block.
[0127] However, if it is requested to retransmit the entire
transmission block even though an error has occurred in only a part
of a transmission block, there occurs a problem that a resource
used for retransmitting the transmission block increases.
[0128] Therefore, in the NR, when there is an error in a part of a
transmission block, it is defined to perform retransmission only
for the part in which the error has occurred, and thereby to
provide a function for reducing resources required for the
retransmission of the transmission block. In this case, the
retransmission is performed on the basis of not a transmission
block but a code block group (CBG) smaller than the transmission
block. Therefore, such a retransmission method is referred to as
CBG based retransmission.
[0129] In the CBG based retransmission, one or more code blocks may
be grouped into one code block group. Thus, a transmission block
may be composed of one or more code block groups.
[0130] When determining whether retransmission is required for a
transmission block, a receiving end checks a CRC of each code block
composing the code block group to inspect whether an error has
occurred. If an error occurs in any of code blocks composing the
code block group, the receiving end requests retransmission of the
code block group.
[0131] If one transmission block is composed of N code block
groups, the receiving end records information indicating which code
block group should be retransmitted among the N code block groups,
in HARQ ACK/NACK for the corresponding transmission block. The
transmitting end may retransmit only the corresponding code block
group indicated for retransmission by receiving the corresponding
HARQ ACK/NACK.
[0132] FIG. 10 is a diagram illustrating a transmission block
configuration for supporting code block group based
retransmission.
[0133] Referring to FIG. 10, the entire transmission block is
composed of a total of 8 code blocks from CB #0 to CB #7. In this
case, i) code blocks CB #0 and CB #1 form a code block group CBG
#0, ii) code blocks CB #2 and CB #3 form a code block group CBG #1,
iii) code blocks CB #4 and CB #5 form a code block group CBG #2,
and iv) code blocks CB #6 and CB #7 form code block group CBG
#3.
[0134] If a CRC error occurs in the code block CB #2 or the code
block CB #3 in a transmission block received by a receiving end,
when transmitting HARQ ACK/NACK information to a transmitting end,
the receiving end configures i) ACK for the code block group CBG
#0, ii) NACK for the code block group CBG #1, iii) ACK for the code
block group CBG #2, and iv) ACK for the code block group CBG #3,
and transmits the configured information.
[0135] When receiving the HARQ ACK/NACK information and identifying
that NACK is set to only the code block group CBG #1, the
transmitting end may perform retransmission only for the
corresponding code block group CBG #1 to the receiving end.
[0136] Information on which code block group is retransmitted among
code block groups forming a transmission block is indicated through
downlink control information (DCI). It is indicated whether or not
a specific code block group is retransmitted through a code block
group transmission indicator (CBGTI, CBG Transmit Indicator) of the
downlink control information. It is also indicated whether or not
soft combining is to be performed for a retransmitted code block
group through a code block group flush indicator (CBGTI, CBG Flush
Indicator) of the downlink control information.
[0137] A frequency, a frame, a subframe, a resource, a resource
block (RB), a region, a band, a sub-band, a control channel, a data
channel, a synchronization signal, various reference signals,
various signals, and various messages associated with NR of the
present disclosure may be interpreted as being used in the past or
present or as various meanings to be used in the future.
[0138] Summary of NR(New Radio)
[0139] Recently, the 3rd generation partnership project (3GPP) has
approved the "Study on New Radio Access Technology", which is a
study item for research on next-generation/5G radio access
technology. On the basis of the Study on New Radio Access
Technology, Radio Access Network Working Group 1 (RAN WG1) has been
discussing frame structures, channel coding and modulation,
waveforms, multiple access methods, and the like for the new radio
(NR).
[0140] The NR is required to be designed not only to provide an
improved data transmission rate as compared with the long term
evolution (LTE)/LTE-Advanced, but also to meet various requirements
of each detailed and specific usage scenario. In particular, an
enhanced mobile broadband (eMBB), massive machine-type
communication (mMTC), and ultra reliable and low latency
communication (URLLC) are proposed as representative usage
scenarios of the NR. In order to meet the requirements of the
individual scenarios, it is required to design frame structures to
be flexible, compared with the LTE/LTE-Advanced.
[0141] Specifically, the eMBB, mMTC, URLLC are considered as
representative usage scenarios of the NR having been discussed in
the 3GPP. Since each usage scenario imposes a different requirement
of data rate, latency, coverage, etc., discussions on necessity for
techniques of efficiently multiplexing radio resource units based
on different types of numerology (e.g., a subcarrier spacing (SCS),
a subframe, a transmission time interval (TTI), etc.) are in
progress as methods for efficiently satisfying requirements of each
usage scenario through a frequency band configuring an NR
system.
[0142] To this end, there have been discussions on i) methods of
multiplexing numerologies having subcarrier spacing (SCS) values
different from one another based on TDM, FDM or TDM/FDM through one
NR carrier, and ii) methods of supporting one or more time units in
configuring a scheduling unit in the time domain.
[0143] In this regard, the NR has defined i) a subframe as one type
of a time domain structure, and as a reference numerology to define
a corresponding subframe duration, ii) a single subframe duration
composed of 14 OFDM symbols of normal CP overhead based on a
subcarrier spacing (SCS) of 15 kHz, which is the same as the LTE.
Therefore, the subframe in the NR has the time duration of 1 ms.
Unlike the LTE, since the subframe in the NR is an absolute
reference time duration, a slot and a minislot may be defined as a
time unit for actual UL/DL data scheduling. In this case, the
number of OFDM symbols included in the slot, a y value, has been
determined to be equals to 14 regardless of numerologies, but not
limited thereto.
[0144] Therefore, a slot may be composed of 14 symbols. In
accordance with a transmission direction for a corresponding slot,
all symbols may be used for DL transmission or UL transmission, or
the symbols may be used in the configuration of a DL portion+a
gap+a UL portion.
[0145] Further, a minislot composed of fewer symbols than the slot
has been defined in a numerology (or SCS), and as a result, a short
time domain scheduling interval may be configured for UL/DL data
transmission or reception based on the minislot. Also, a long time
domain scheduling interval may be configured for the UL/DL data
transmission or reception by slot aggregation.
[0146] In particular, in the case of transmission/reception of
latency-critical data, such as the URLLC, it may be difficult to
meet latency requirements when scheduling is performed on the basis
of a slot having 0.5 ms (7 symbols) or 1 ms (14 symbols) defined in
a frame structure based on a numerology having a small SCS value
such as 15 kHz. To solve this problem, by defining a minislot
composed of fewer OFDM symbols than the slot, it is possible to
enable scheduling for latency-critical data, such as the URLLC, to
be performed based on the minislot.
[0147] Further, methods have been discussed for scheduling data
according to latency requirements based on a slot (or a minislot)
length defined for each numerology, by multiplexing numerologies
having different SCS values from one another in one NR carrier,
using the TDM or FDM technique, as described above. For example, as
shown in FIG. 2, since a symbol length for the SCS of 60 kHz is
reduced by about a fourth of that for the SCS of 15 kHz, when one
slot is composed of seven OFDM symbols in both the cases, a slot
length based on the SCS of 15 kHz is 0.5 ms, whereas a slot length
based on the SCS of 60 kHz reduces to about 0.125 ms.
[0148] As described above, discussion on methods of satisfying each
requirement of URLLC and eMBB is in progress by defining different
SCSs or different TTI lengths in the NR.
[0149] NR PDCCH
[0150] Physical layer control information, such as DL allocation
downlink control information (DCI) and UL grant DCI is transmitted
and received through the PDCCH, in the NR and LTE/LTE-A systems. A
control channel element (CCE) is defined as a resource unit for
transmission of the PDCCH. In the NR, a CORESET (Control Resource
Set), which is a frequency/time resource for PDCCH transmission,
may be configured for each UE, with reference to FIG. 7, as
described above. In addition, each CORESET may be composed of one
or more search spaces configured by one or more PDCCH candidates
for monitoring the PDCCH by a UE.
[0151] Wider Bandwidth Operations
[0152] A typical LTE system supports scalable bandwidth operations
for an LTE component carrier (CC). An LTE service provider may
organize a bandwidth of at least 1.4 MHz up to 20 MHz according to
a frequency deployment scenario when configuring one LTE CC.
Accordingly, any normal LTE UE supports transmission/reception
capabilities of the bandwidth of 20 MHz for one LTE CC.
[0153] However, the NR is designed for enabling UEs having
transmission/reception bandwidth capabilities different from one
another to be supported in one broadband NR component carrier.
Accordingly, as illustrated in FIG. 4, it is required to i)
configure one or more bandwidth parts (BWPs) composed of subdivided
bandwidths for an NR component carrier (CC), and ii) support
flexible wider bandwidth operations by configuring and activating
BWPs different from one another for each UE.
[0154] Specifically, in the NR, one or more BWPs may be configured
through one serving cell configured from a UE perspective. The
corresponding UE may transmit/receive UP/DL data by activating one
DL BWP and one UP BWP in the serving cell. In addition, in a case
where a plurality of serving cells are established on a UE, that
is, carrier aggregation (CA) is applied to the UE, it is possible
to activate one DL bandwidth part and/or one UL BWP for each
serving cell, and then transmit and/or receive UP/DL data using a
radio resource of each serving cell.
[0155] Specifically, an initial bandwidth part may be defined for
an initial access procedure in a serving cell, and one or more
UE-specific BWPs may be configured through RRC signaling dedicated
for each UE, and a default bandwidth part may be defined for a
fallback operation for each UE.
[0156] In this case, it may be defined to activate and use a
plurality of downlink and/or uplink BWPs simultaneously according
to the configurations of BWPs and capabilities of a UE in any
serving cell. In this regard, NR rel-15 defines to activate and use
only one DL BWP and one UL BWP in any UE at any time.
[0157] NR MCS & TBS Determination
[0158] In the typical LTE system, a base station transmits
modulation and coding scheme (MCS) indication information for PDSCH
or PUSCH transmission/reception to a UE through downlink control
information (DCI). Also, based on an MCS table or a TBS table, a
modulation order and a transport block size (TBS) index are mapped
according to the MCS indication information, i.e., MCS index
information, indicated through the DCI, and a TBS is mapped based
on the TBS index and the number of allocated TBSs. Details of
methods of configuring an MCS and a relevant TBS can be found in
the documents of 3GPP TS 36.213 and TS 38.214.
[0159] Also, methods of determining the MCS and the TBS of the LTE
may be applied equally in the NR.
[0160] In the present disclosure, a method and apparatus are
proposed for configuring the MCS and the TBS to support data
transmission with different target BLERs in NR or LTE/LTE-A
systems.
[0161] As a usage scenario provided by the NR and the LTE/LTE-A
systems, there is increasing importance of methods for effectively
supporting, as well as data related to the eMBB service to maximize
data transmission rate, data related to the URLLC service to
maximize reliability.
[0162] In particular, since the URLLC requires an improved target
BLER (Block Error Rate) compared with a target BLER for typical
eMBB data, therefore, it is required to design a new MCS table or
TBS table is required for this purpose.
[0163] In this present disclosure, a method and apparatus are
proposed for efficiently operating a MCS table or a TBS table based
on different target BLERs if the MCS table or the TBS table is
defined as described above.
[0164] As described above, there occurs a difference between
reliability requirements required for data transmission according
to usage scenarios, and accordingly, target BLERs for data
transmission, i.e. PDSCH transmission or PUSCH transmission, may be
different. To satisfy such separate target BLERs, it is required to
define i) a separate CQI table for CQI reporting of a UE for each
target BLER, and ii) a separate MCS table for each target BLER.
[0165] For example, in the case of an MCS table optimized for
maximizing the transmission rate, such as in the eMBB, it is
possible to configure an MCS table based on higher order
modulation. For example, in the case of an MCS table for
reliability-critical data, such as in the URLLC, it is possible to
configure an MCS table based on lower order modulation. That is,
according to the target BLER values, as the target BLER is higher,
it is possible to configure an MCS table having an MCS index based
on a higher order modulation scheme such as 64QAM, 256QAM, or
1024QAM. As the target BLER is lower, it is possible to configure
another MCS table having an MCS index based on a lower order
modulation scheme such as QPSK or 16 QAM may be constructed.
[0166] Accordingly, in the NR or the LTE/LTE-A systems, a separate
CQI table for CQI or CSI reporting of a UE may be defined for each
target BLER. That is, it is possible to define a plurality of CQI
tables. Accordingly, i) a base station or a network may configure
configuration information on a CQI table to be applied for CQI
reporting in a UE based on a target BLER required for each UE
through higher layer signaling, and ii) MCS table configuration may
be performed according to the configured CQI table information.
[0167] That is, a plurality of different CQI tables may be defined
according to target BLERs for data transmission/reception. CQI
table configuration information to be applied for CQI reporting for
each UE may be configured by the base station and transmitted to
each UE through higher layer signaling. For example, CQI table A,
CQI table B, CQI table C, . . . etc. may be defined for each target
BLER, and a CQI table to be applied to each UE may be configured.
Further, it is possible to define a plurality of different MCS
tables or TBS tables for data transmission/reception through the
PDSCH/PUSCH for each target BLER or for each relevant CQI
table.
[0168] That is, MCS table A, MCS table B, MCS table C, . . . , etc.
may be defined for each target BLER or for each relevant CQI table.
An MCS table to be applied for data channel transmission/reception
for each UE may be defined to be determined according to CQI table
configuration information. As another example, MCS table A, MCS
table B, MCS table C, . . . , etc. may be defined for each target
BLER or for each relevant CQI table. A TBS table to be applied for
data channel transmission/reception for each UE may be defined to
be determined according to the CQI table configuration
information.
[0169] As another method of configuring the CQI table and the
relevant MCS table or TBS table, a method may be defined for
selecting a dynamic MCS table or TBS table. For example, it is
possible to configure simultaneously both a session (i.e., an
eMBB-based service) that requires a high data transmission rate and
a session (i.e., a URLLC service) that requires high reliability,
for any one UE. Accordingly, it may be necessary for one UE to
simultaneously support data transmission based on different target
BLERs.
[0170] In this case, as described above, it is required to
configure a dynamic MCS table or TBS table for each PDSCH or PUSCH
transmission other than a method of configuring a semi-static MCS
table or TBS table through higher layer signaling.
[0171] In this case, a plurality of CQI reporting or CSI reporting
processes may be established in a base station or a network for any
one UE. A separate CQI table to be applied for CQI reporting is
configured for each CQI reporting or CSI reporting process, and
then information on the configured separate CQI table may be
transmitted to a corresponding UE through higher layer
signaling.
[0172] In addition, when the eMBB-based service and the URLLC-based
service are simultaneously supported for any one UE, target BLERs
may be different for each PDSCH or PUSCH transmission for the
corresponding UE, as described above. Accordingly, it is necessary
to define a method of dynamically configuring an MCS table to be
applied for each PDSCH or PUSCH transmission.
[0173] As a method for this, a base station may be defined to
dynamically configure information for selecting an MCS table to be
applied through scheduling DCI on the PDSCH or PUSCH and then
signals to a corresponding UE. That is, in configuring a DL
allocation DCI format or a UL grant DCI format for a UE, it may be
defined to include an information area or an information field for
selecting the MCS table.
[0174] As another method for selecting the MCS table through
scheduling DCI on the PDSCH or the PUSCH, corresponding information
may be implicitly signaled through the scheduling DCI.
[0175] For example, the MCS table selection information may be
implicitly determined by a RNTI for PDCCH decoding of a UE. That
is, when such a new MCS table for the URLLC is configured for a UE,
the base station may allocate a new RNTI for the new MCS table
through higher layer signaling. For example, an MCS-C-RNTI may be
allocated for applying the new MCS table for the URLLC. The UE may
derive corresponding MCS table selection information based on the
MCS-C-RNTI, which is the new RNTI. The MCS-C-RNTI is scrambled by a
CRC of the PDCCH.
[0176] Specifically, in addition to scheduling control information
based on a MCS table defined for providing the typical eMBB
service, i.e., the C-RNTI or the CS-RNTI allocated for UE-specific
DL allocation DCI or UL grant DCI transmission/reception, it is
possible to define i) separately scheduling control information
based on an MCS table newly defined for the URLLC, i.e., the
MCS-C-RNTI or the MCS-CS-RNTI for UE-specific DL allocation DCI or
UL grant transmission/reception, and ii) an MCS table to be
selected based on this.
[0177] The new MCS-C-RNTI or MCS-CS-RNTI for the URLLC is either
explicitly allocated by the base station through higher layer
signaling or defined as a function of the typical C-RNTI or CS-RNTI
allocated for the UE. For example, a value obtained by adding a
specific value to the allocated C-RNTI or CS-RNTI may be defined as
an MCS-C-RNTI or MCS-CS-RNTI value for DCI transmission/reception
based on the MCS table defined for the URLLC.
[0178] Whether an information area for selecting an MCS table is
included in the DL allocation DCI format or the UL grant DCI format
configured for monitoring by a UE may be i) configured through
higher layer signaling for each UE, or ii) implicitly determined
depending on whether a plurality of CQI reports or CSI reports
based on different CQI tables for each target BLER is
configured.
[0179] That is, when a plurality of CQI reports or CSI reports
based on CQI tables different from one another are configured, the
DL allocation DCI format or the UL grant DCI format for a
corresponding UE may be defined to include an information area for
selecting an MCS table. Otherwise, the DL allocation DCI format or
the UL grant DCI format for the corresponding UE may be defined not
to include the information area for selecting an MCS table.
[0180] In addition, the size of the information area for selecting
an MCS table is determined i) by the maximum number of MCS tables,
an N vale (eg, log 2N bits), for each target BLER defined in the NR
system or the LTE/LTE-A system, or ii) by the number of the CQI
tables, a M value (Eg, log 2M bits), applied by CQI or CSI
reporting processes established for a corresponding UE, and the M
value.
[0181] As another method for configuring the MCS table, it may be
defined to configure an MCS table to be applied for each CORESET or
search space configured for a UE. For example, when a CORESET is
configured for a UE, it is possible to define that a base station
i) configures MCS information included in the PDCCH transmitted
through the CORESET, more specifically DL allocation DCI or UL
grant DCI, ii) configures an MCS table for interpreting the MCS
information, and iii) transmits it to the corresponding UE through
higher layer signaling.
[0182] For example, when CORESET A, CORESET B, and CORESET C are
configured for a UE, and support for MCS table A and MCS table B
according to target BLER A and target BLER B for data transmission
required by the UE is required, it is possible to define that the
base station configures MCS configuration information included in
the DL allocation DCI or the UL grant DCI for each CORESET and
transmits MCS table configuration information used for determining
by the UE which one of the MCS table A and the MCS table B is
applied through higher layer signaling.
[0183] That is, when configuration or reconfiguration information
for each CORESET A, CORESET B, and CORESET C is transmitted, it is
possible to define that the configuration or reconfiguration
information includes MCS table configuration information to be
applied to the DL allocation DCI or the UL grant DCI transmitted
through a corresponding CORESET.
[0184] As another example, the MCS table to be applied may be
configured for each search space configured in a CORESET or through
a plurality of CORESETs. For example, a base station may configure
the MCS table to be applied for each search space and transmit to a
US through higher layer signaling.
[0185] As another example, the MCS table may be implicitly
configured by each search space kind/type (e.g., CSS or UE-specific
SS) or an aggregation level (AL) of PDCCH candidates composing each
search space.
[0186] As another example, the search space may be defined as a set
of CCEs composed of PDCCH candidates based on an aggregation level
(AL). Accordingly, the MCS table is configured for each search
space, which may be construed in the same meaning as the MCS table
is configured for each set of PDCCH candidates composed for each
aggregation level (AL).
[0187] As another method for configuring the MCS table, an MCS
table may be defined to be implicitly applied is determined
according to a transmission method of the PDCCH. For example, the
MCS table to be applied may be determined according to i) whether
interleaving is applied, or PDCCH is repeatedly transmitted, or ii)
a bundle size.
[0188] As another method for configuring the MCS table to be
applied, an MCS table to be applied may be configured for each DCI
format configured to monitor by a UE. Specifically, a DL allocation
DCI format or UL grant DCI format and an MCS table to be applied
may be separately defined, for each target BLER.
[0189] For example, when data transmission/reception based on
target BLER A and target BLER B is supported in an NR system or
LTE/LTE-A system, it is possible to define an MCS table for the
target BLER A, and one or more DL allocation or UL grant DCI
formats based on this. In addition, an MCS table for the target
BLER B and one or more DL allocation or UL Grant DCI formats may be
defined separately from each other. Accordingly, the MCS table to
be applied may be defined to be implicitly mapped according to the
DCI format configured for monitoring by a UE through a CORESET or
search space.
[0190] As another example, when a DCI format for monitoring by each
UE is configured or a PDSCH/PUSCH transmission mode is set, it is
possible to define that the MCS table configuration information to
be applied, which is included in data or information to be
transmitted by the configuration or the setting, is explicitly
transmitted to the UE through higher layer signaling.
[0191] In this case, the higher layer signaling includes MAC CE
signaling or RRC signaling and may be cell-specific or UE-specific
higher layer signaling.
[0192] In the present disclosure, methods are proposed for
configuring an MCS table for PDSCH/PUSCH transmission for a UE when
different MCS tables are defined for each target BLER, and
embodiments of the present disclosure may be applied regardless of
a specific method for configuring an MCS table for each target
BLER.
[0193] In configuring a plurality of MCS tables described above,
when a plurality of TBS tables are defined for each target BLER,
TBS table configuration and selection methods may be applied in the
same manner as the MCS table configuration and selection
methods.
[0194] In addition, in a case where a plurality of CQI or MCS
tables are defined for each target BLER for data transmission in
the NR or LTE/LTE-A systems, as described above, it is possible to
define a default (or fallback) CQI table or MCS table for each UE.
The default MCS table may be defined as an MCS table to be applied
in fallback operation of a corresponding UE.
[0195] For example, in the case of a UE-specific DCI (e.g., DL
allocation DCI or UL grant DCI) transmitted through a common search
space (CSS) or a fallback DCI format, a base station may configure
an MCS index based on a default MCS table defined for a
corresponding UE, and then cause the UE to construe it, regardless
of the MCS table configuration method and the resultant UE-specific
MCS table configuration information. The default MCS table may be
defined in such a manner that i) a specific MCS table for each
system/network may be fixed as a default MCS table for all UEs
based on the corresponding system/network, ii) each separate MCS
table according to capabilities of UEs, etc. may be defined as a
default MCS table, or iii) a default MCS table may be configured by
the corresponding network through cell-specific higher layer
signaling or UE-specific higher layer signaling.
[0196] In addition, one or more cases/embodiments where a MCS table
is selected from any or all combinations of the above-described
methods may be included in the scope of the present disclosure.
[0197] As described above, in a case where an MCS table or a TBS
table based on different target BLERs is defined, a method and
apparatus have been described for efficiently operating the MCS
table or the TB S table. Hereinafter, referring to FIGS. 10 to 13,
methods and apparatuses will be described for
transmitting/receiving control information for a physical data
channel, such as a PDSCH or a PUSCH through a physical downlink
control channel and transmitting/receiving a physical data channel.
Although the methods and apparatuses will be described using some
of the embodiments described above, they are equally applicable to
other embodiments.
[0198] FIG. 11 is a flow chart illustrating a method of a base
station for transmitting control information on a physical uplink
shared channel according to an embodiment of the present
disclosure.
[0199] Referring to FIG. 11, a method of a base station is provided
for transmitting control information on a physical uplink data
channel (physical uplink shared channel). The method 1100 includes
transmitting control information indicating a specific modulation
and coding scheme (MCS) index corresponding to modulation and
coding scheme (MCS) information to be applied to the physical
uplink shared channel through a physical downlink control channel
(S1110), and receiving the physical uplink shared channel modulated
based on specific MCS information determined using the specific MCS
index and one of two or more MCS tables containing modulation order
information corresponding to the specific MCS index (S1120). These
MCS tables may additionally include a target code rate
corresponding to the specific MCS index, which is calculated by the
target BLER described above and spectral efficiency.
[0200] In the transmitting S1110, a UL grant DCI format for a UE
may include an information region or an information field
indicating the specific modulation and coding scheme (MCS) index
corresponding to the specific modulation and coding scheme (MCS)
information. This information field may be an MCS index field.
[0201] At least one of the two or more MCS tables may be an MCS
table based on a higher modulation order including 64QAM or 256QAM,
and another of the MCS tables may be an MCS table based on a lower
modulation order including QPSK or 16QAM.
[0202] For example, in the case of an MCS table optimized for
maximizing the transmission rate, such as the eMBB, an MCS table
may be configured based on higher order modulation. For example, in
the case of an MCS table for reliability-critical data, such as in
the URLLC, an MCS table may be configured based on lower order
modulation. That is, according to the target BLER values, as a
corresponding target BLER is higher, an MCS table having an MCS
index may be configured based on a higher order modulation scheme
such as 64QAM, 256QAM, or 1024QAM. As a target BLER is lower,
another MCS table having an MCS index may be configured based on a
lower order modulation scheme such as QPSK or 16 QAM.
[0203] The base station may implicitly signal information for
selecting one of the two or more MCS tables through UL grant DCI
for the PUSCH.
[0204] One of the two or more MCS tables may be determined by an
RNTI value scrambled with a CRC of the physical downlink control
channel (PDCCH). The RNTI may be a new MCS-C-RNTI or a new
MCS-CS-RNTI that is additionally allocated for the URLLC other than
a typical C-RNTI and a typical CS-RNTI.
[0205] For example, the information for selecting one of two or
more MCS tables may be implicitly determined by a RNTI for PDCCH
decoding of the UE. That is, when such a new MCS table for the
URLLC is configured for any UE, a new RNTI for the new MCS table,
i.e., an MCS-C-RNTI or an MCS-CS-RNTI may be allocated by the base
station through higher layer signaling. The UE may derive
information for selecting one of two or more MCS tables based on
the new RNTI, i.e., the MCS-C-RNTI or the MCS-CS-RNTI.
[0206] Specifically, in addition to scheduling control information
based on an MCS table defined for providing the typical eMBB
service, i.e., the C-RNTI or the CS-RNTI allocated for UE-specific
DL allocation DCI or UL grant DCI transmission/reception, i)
scheduling control information may be separately defined based on
an MCS table newly defined for the URLLC, i.e., the new RNTI (e.g.,
the MCS-C-RNTI or the MCS-CS-RNTI) for UE-specific DL allocation
DCI or UL grant transmission/reception, and ii) one of two or more
MCS tables may be selected based on this newly defined
information.
[0207] As another method of selecting one of two or more MCS
tables, an MCS table to be applied may be selected for each search
space configured for any UE.
[0208] One of the two or more MCS tables may be determined by a
type of search space through which physical downlink control
channel (PDCCH) transmission is performed. The type of search space
may be a UE-specific search space.
[0209] That is, the MCS table may be implicitly configured by each
search space kind/type (e.g., CS or UE-specific SS) through which
the physical downlink control channel (PDCCH) transmission is
performed.
[0210] In the receiving S1120, the base station receives the
physical uplink shard channel (PUSCH) modulated based on the
specific MCS information determined using the specific MCS index
and one of the two or more MCS tables.
[0211] That is, the UE determines the specific MCS information
using the specific MCS index and one of two or more MCS tables. The
UE encodes the physical uplink shard channel (PUSCH) based on the
specific MCS information.
[0212] The UE transmits this physical uplink shared channel (PUSCH)
to the base station. The base station receives this physical uplink
shared channel (PUSCH) from the UE.
[0213] FIG. 12 is a flowchart illustrating a method of a UE for
receiving control information on a physical data channel according
to an embodiment of the present disclosure.
[0214] Referring to FIG. 12, a method of a UE is provided for
receiving control information on a physical data channel. The
method 1200 includes receiving control information indicating a
specific modulation and coding scheme (MCS) index corresponding to
modulation and coding scheme (MCS) information on a physical data
channel through a physical downlink control channel (S1210), and
determining specific MCS information used for the physical data
channel using the specific MCS index and one of two or more MCS
tables containing modulation order information corresponding to the
specific MCS index (S1220). These MCS tables may additionally
include a target code rate corresponding to the specific MCS index,
which is calculated by the target BLER described above and spectral
efficiency.
[0215] The physical data channel may be a physical downlink
data/shard channel (PDSCH) or a physical uplink data/shard channel
(PUSCH).
[0216] In the receiving S1210, a DL allocation DCI format and a UL
grant DCI format for any UE may include an information area or an
information field indicating the specific modulation and coding
scheme (MCS) index corresponding to the specific modulation and
coding scheme (MCS) information. This information field may be an
MCS index field. A format of the physical downlink control channel
indicating an MCS index for the physical downlink shard channel and
a format of the physical downlink control channel indicating an MCS
index for the physical uplink shard channel may be different from
each other.
[0217] At least one of the two or more MCS tables may be an MCS
table based on a higher modulation order including 64QAM or 256QAM,
and another of the MCS tables may be an MCS table based on a lower
modulation order including QPSK or 16QAM.
[0218] For example, in the case of an MCS table optimized for
maximizing the transmission rate, such as the eMBB, an MCS table
may be configured based on higher order modulation. For example, in
the case of an MCS table for reliability-critical data, such as in
the URLLC, an MCS table may be configured based on lower order
modulation. That is, according to the target BLER values, as a
corresponding target BLER is higher, an MCS table having an MCS
index may be configured based on a higher order modulation scheme
such as 64QAM, 256QAM, or 1024QAM. As a target BLER is lower,
another MCS table having an MCS index may be configured based on a
lower order modulation scheme such as QPSK, or 16 QAM may be
constructed.
[0219] A base station may implicitly signal information for
selecting one of the two or more MCS tables through DL allocation
DCI for the PDSCH and UL grant DCI for the PUSCH. The UE derives
one of two or more MCS tables, which have been signaled implicitly,
through the DL allocation DCI for the PDSCH and the UL grant DCI
for the PUSCH.
[0220] One of the two or more MCS tables may be determined by an
RNTI value scrambled with a CRC of the physical downlink control
channel (PDCCH). The RNTI may be a new MCS-C-RNTI or a new
MCS-CS-RNTI that is additionally allocated for the URLLC other than
a typical C-RNTI and a typical CS-RNTI.
[0221] For example, the information for selecting one of two or
more MCS tables may be implicitly determined by a RNTI for PDCCH
decoding of the UE. That is, in a case where such a new MCS table
for the URLLC is configured for any UE, the base station may
allocate a new RNTI for the new MCS table, i.e., an MCS-C-RNTI or
an MCS-CS-RNTI through higher layer signaling. The UE may derive
information for selecting one of two or more MCS tables based on
the new RNTI, i.e., the MCS-C-RNTI or the MCS-CS-RNTI.
[0222] Specifically, in addition to scheduling control information
based on an MCS table defined for providing the typical eMBB
service, i.e., the C-RNTI or the CS-RNTI allocated for UE-specific
DL allocation DCI or UL grant DCI transmission/reception, i)
scheduling control information may be separately defined based on
an MCS table newly defined for the URLLC, i.e., the new RNTI (e.g.,
the MCS-C-RNTI or the MCS-CS-RNTI) for UE-specific DL allocation
DCI or UL grant transmission/reception, and ii) one of two or more
MCS tables may be selected based on this newly defined
information.
[0223] As another method of selecting one of two or more MCS
tables, an MCS table to be applied may be selected for each search
space configured for any UE.
[0224] One of the two or more MCS tables may be determined
according to a type of search space through which physical downlink
control channel (PDCCH) transmission is performed. The type of
search space may be a UE-specific search space.
[0225] That is, the MCS table may be implicitly configured based on
each search space kind/type (e.g., CS or UE-specific SS) through
performing the physical downlink control channel (PDCCH)
transmission.
[0226] In the determining S1220, the UE determines the specific MCS
information using the specific MCS index and one of two or more MCS
tables.
[0227] For example, when the physical data channel is a physical
downlink shard channel (PDSCH), the base station may encode the
physical downlink shard channel (PDSCH) based on the specific MCS
information. The UE decodes the physical downlink shard channel
(PDSCH) based on the specific MCS information.
[0228] For example, when the physical data channel is a physical
uplink shard channel (PUSCH), the UE encodes the physical uplink
shard channel (PDSCH) based on the specific MCS information. The UE
transmits this physical uplink shared channel (PUSCH) to the base
station. The base station receives this physical uplink shared
channel (PUSCH) from the UE.
[0229] FIG. 13 is a block diagram illustrating a base station
according to an embodiment of the present disclosure.
[0230] Referring to FIG. 13, a base station 1300 according to an
embodiment includes a controller 1310, a transmitter 1320, and a
receiver 1330.
[0231] The controller 1310 controls the overall operation of the
base station 1300 for performing a method in which a separate MCS
table is configured for each target BLER, as a method for
configuring a MCS and a TBS in the NR required to perform the
above-described embodiments of the present discharge.
[0232] The transmitter 1320 and the receiver 1330 are used to
transmit to and receive, from a UE, signals, messages, and data
necessary for carrying out the present disclosure described
above.
[0233] A UL grant DCI format for the UE may include an information
area or an information field indicating a specific modulation and
coding scheme (MCS) index corresponding to specific modulation and
coding scheme (MCS) information. This information field may be an
MCS index field.
[0234] At least one of two or more MCS tables may be an MCS table
based on a higher modulation order including 64QAM or 256QAM, and
another of the MCS tables may be an MCS table based on a lower
modulation order including QPSK or 16QAM.
[0235] For example, in the case of an MCS table optimized for
maximizing the transmission rate, such as the eMBB, an MCS table
may be configured based on higher order modulation. For example, in
the case of an MCS table for reliability-critical data, such as in
the URLLC, an MCS table may be configured based on lower order
modulation. That is, according to target BLER values, as a target
BLER is higher, an MCS table having an MCS index may be configured
based on a higher order modulation scheme such as 64QAM, 256QAM, or
1024QAM. As a target BLER is lower, another MCS table having an MCS
index may be configured based on a lower order modulation scheme
such as QPSK or 16 QAM.
[0236] The base station may implicitly signal information for
selecting one of two or more MCS tables through UL grant DCI for a
PUSCH.
[0237] One of two or more MCS tables may be determined by an RNTI
value scrambled with a CRC of a physical downlink control channel
(PDCCH). The RNTI may be a new MCS-C-RNTI or a new MCS-CS-RNTI that
is additionally allocated for the URLLC other than a typical C-RNTI
and a typical CS-RNTI.
[0238] For example, the information for selecting one of two or
more MCS tables may be implicitly determined by a RNTI for PDCCH
decoding of the UE. That is, when such a new MCS table for the
URLLC is configured for any UE, a new RNTI for the new MCS table,
i.e., an MCS-C-RNTI or an MCS-CS-RNTI may be allocated. The
controller 1310 may scramble a CRC of the physical downlink control
channel (PDCCH) with the new RNTI, e.g., the MCS-C-RNTI or the
MCS-CS-RNTI.
[0239] Specifically, in addition to scheduling control information
based on an MCS table defined for providing the typical eMBB
service, i.e., the C-RNTI or the CS-RNTI allocated for UE-specific
DL allocation DCI or UL grant DCI transmission/reception, i)
scheduling control information may be separately defined based on
an MCS table newly defined for the URLLC, i.e., the new RNTI (e.g.,
the MCS-C-RNTI or the MCS-CS-RNTI) for UE-specific DL allocation
DCI or UL grant transmission/reception, and ii) one of two or more
MCS tables may be selected based on this newly defined
information.
[0240] As another method of selecting one of two or more MCS
tables, an MCS table to be applied may be selected for each search
space configured for any UE.
[0241] One of the two or more MCS tables may be determined by a
type of search space through which physical downlink control
channel (PDCCH) transmission is performed. The type of search space
may be a UE-specific search space.
[0242] That is, the MCS table may be implicitly configured by each
search space kind/type (e.g., CS or UE-specific SS) through which
the physical downlink control channel (PDCCH) transmission is
performed.
[0243] The receiver S1120 receives the physical uplink shard
channel (PUSCH) modulated based on specific MCS information
determined using the specific MCS index and one of the two or more
MCS tables.
[0244] That is, the UE determines the specific MCS information
using the specific MCS index and one of two or more MCS tables. The
UE encodes the physical uplink shard channel (PUSCH) based on the
specific MCS information.
[0245] The UE transmits this physical uplink shared channel (PUSCH)
to the base station. The receiver 1330 receivers this physical
uplink shared channel (PUSCH) from the UE.
[0246] FIG. 14 is a block diagram illustrating a UE according to an
embodiment of the present disclosure.
[0247] Referring to FIG. 14, a UE 1400 according to another
embodiment includes a receiver 1410, a controller 1420, and a
transmitter 1430.
[0248] The receiver 1410 receives downlink control information and
data, messages through a corresponding channel from a base
station.
[0249] The controller 1420 controls the overall operation of the UE
1400 for performing a method in which a separate MCS table is
configured for each target BLER, as a method for configuring a MCS
and a TBS in the NR required to perform the above-described
embodiments of the present discharge.
[0250] The transmitter 1430 transmits uplink control information
and data, messages through a corresponding channel to the BS.
[0251] A physical data channel may be a physical downlink
data/shard channel (PDSCH) or a physical uplink data/shard channel
(PUSCH).
[0252] As described above, a downlink allocation DCI format and an
uplink grant DCI format for a UE may include an information area or
an information field indicating the specific modulation and coding
scheme (MCS) index corresponding to the specific modulation and
coding scheme (MCS) information. This information field may be an
MCS index field. A format of a physical downlink control channel
indicating an MCS index for the physical downlink shard channel and
a format of a physical downlink control channel indicating an MCS
index for the physical uplink shard channel may be different from
each other.
[0253] At least one of two or more MCS tables may be an MCS table
based on a higher modulation order including 64QAM or 256QAM and
another of the MCS tables may be an MCS table based on a lower
modulation order including QPSK or 16QAM.
[0254] For example, in the case of an MCS table optimized for
maximizing the transmission rate, such as the eMBB, an MCS table
may be configured based on higher order modulation. For example, in
the case of an MCS table for reliability-critical data, such as in
the URLLC, an MCS table may be configured based on lower order
modulation. That is, according to target BLER values, as a target
BLER is higher, an MCS table having an MCS index may be configured
based on a higher order modulation scheme such as 64QAM, 256QAM, or
1024QAM. As a target BLER is lower, another MCS table having an MCS
index may be configured based on a lower order modulation scheme
such as QPSK or 16 QAM.
[0255] The base station may implicitly signal information for
selecting one of the two or more MCS tables through DL allocation
DCI for the PDSCH and UL grant DCI for the PUSCH. The controller
1420 derives one of two or more MCS tables, which have been
signaled implicitly, through the DL allocation DCI for the PDSCH
and the UL grant DCI for the PUSCH.
[0256] One of two or more MCS tables may be determined by an RNTI
value scrambled with a CRC of the physical downlink control channel
(PDCCH). The RNTI may be a new MCS-C-RNTI or a new MCS-CS-RNTI that
is additionally allocated for the URLLC other than a typical C-RNTI
and a typical CS-RNTI.
[0257] The controller 1420 selects one of two or more MCS tables
based on the RNTI value scrambled with the CRC of the physical
downlink control channel (PDCCH), i.e., the MCS-C-RNTI or the
MCS-CS-RNTI.
[0258] For example, information for selecting one of two or more
MCS tables may be implicitly determined by a RNTI for PDCCH
decoding of the UE. That is, in a case where such a new MCS table
for the URLLC is configured for any UE, a new RNTI for the new MCS
table, i.e., an MCS-C-RNTI or an MCS-CS-RNTI may be allocated. The
controller 1429 may derive information for selecting one of two or
more MCS tables based on the new RNTI, i.e., the MCS-C-RNTI or the
MCS-CS-RNTI.
[0259] Specifically, in addition to scheduling control information
based on an MCS table defined for providing the typical eMBB
service, i.e., the C-RNTI or the CS-RNTI allocated for UE-specific
DL allocation DCI or UL grant DCI transmission/reception, i)
scheduling control information may be separately defined based on
an MCS table newly defined for the URLLC, i.e., the new RNTI (e.g.,
the MCS-C-RNTI or the MCS-CS-RNTI) for UE-specific DL allocation
DCI or UL grant transmission/reception, and ii) one of two or more
MCS tables may be selected based on this newly defined
information.
[0260] As another method of selecting one of two or more MCS
tables, an MCS table to be applied may be selected for each search
space configured for any UE.
[0261] One of the two or more MCS tables may be determined by a
type of search space through which physical downlink control
channel (PDCCH) transmission is performed. The type of search space
may be a UE-specific search space.
[0262] That is, the MCS table may be implicitly configured by each
search space kind/type (e.g., CS or UE-specific SS) through which
the physical downlink control channel (PDCCH) transmission is
performed.
[0263] That is, the controller 1420 determines specific MCS
information using a specific MCS index and one of two or more MCS
tables.
[0264] For example, when the physical data channel is a physical
downlink shard channel (PDSCH), the base station may encode the
physical downlink shard channel (PDSCH) based on the specific MCS
information. The controller 1420 decodes the physical downlink
shard channel (PDSCH) based on the specific MCS information.
[0265] For example, when the physical data channel is the physical
uplink shard channel (PUSCH), the UE encodes the physical uplink
shard channel (PDSCH) based on the specific MCS information. The
transmitter 1430 transmits this physical uplink shared channel
(PUSCH) to the base station. The base station receives this
physical uplink shared channel (PUSCH) from the UE.
[0266] The embodiments described above may be supported by the
standard documents disclosed in at least one of the wireless access
systems IEEE 802, 3GPP and 3GPP2. That is, the steps,
configurations, and parts not described in the present embodiments
for clarifying the technical idea may be supported by standard
documents described above. In addition, all terms disclosed herein
may be described by the standard documents described above.
[0267] The embodiments described above may be implemented by
various means. For example, the embodiments of the present
disclosure may be implemented by hardware, firmware, software, or a
combination thereof.
[0268] In the case of hardware implementation, the method according
to embodiments may be implemented by one or more of application
specific integrated circuits (ASICs), digital signal processors
(DSPs), digital signal processing devices (DSPDs), programmable
logic devices (PLDs) (Field Programmable Gate Arrays), a processor,
a controller, a microcontroller, a microprocessor, or the like.
[0269] In the case of an implementation by firmware or software,
the method according to the embodiments may be implemented in the
form of an apparatus, a procedure, or a function for performing the
functions or operations described above. The software code may be
stored in a memory unit and driven by the processor. The memory may
be located inside or outside the processor, and may exchange data
with the processor by various well-known means.
[0270] The terms "system", "processor", "controller", "component",
"module", "interface", "model", "unit", and the like, described
above may generally refer to computer-related entity hardware, a
combination of hardware and software, software, or software in
execution. For example, components described above may be, but are
not limited to, a process driven by a processor, a processor, a
controller, a control processor, an entity, an execution thread, a
program and/or a computer. For example, an application running on a
controller, controller or processor can be a component. One or more
components can be included within a process and/or thread of
execution, and a component can be placed on one system or be
disposed on more than one system.
[0271] The features, structures, configurations, and effects
described in the present disclosure are included in at least one
embodiment but are not necessarily limited to a particular
embodiment. A person skilled in the art can apply the features,
structures, configurations, and effects illustrated in the
particular embodiment embodiments to another one or more additional
embodiment embodiments by combining or modifying such features,
structures, configurations, and effects. It should be understood
that all such combinations and modifications are included within
the scope of the present disclosure. Accordingly, the embodiments
of the present disclosure are intended to be illustrative rather
than limiting, and the scope of the present invention is not
limited by these embodiments. The scope of protection of the
present disclosure is to be construed according to the claims, and
all technical ideas within the scope of the claims should be
interpreted as being included in the scope of the present
invention.
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