U.S. patent number RE48,004 [Application Number 15/590,322] was granted by the patent office on 2020-05-19 for method for transmitting control information and apparatus for same.
This patent grant is currently assigned to LG ELECTRONICS INC.. The grantee listed for this patent is LG ELECTRONICS INC.. Invention is credited to Joonkui Ahn, Mingyu Kim, Dongyoun Seo, Suckchel Yang.
View All Diagrams
United States Patent |
RE48,004 |
Yang , et al. |
May 19, 2020 |
Method for transmitting control information and apparatus for
same
Abstract
The present invention relates to a wireless communication
system. More particularly, the present invention relates to a
method for transmitting uplink channel state information (CSI) in a
wireless communication system that supports carrier aggregation,
and to an apparatus for the method. The method for reporting CSI in
a wireless communication system that supports carrier aggregation
comprises the steps of: configuring a plurality of downlink
component carriers (DL CCs); setting a CSI report mode on the
plurality of DL CCs for each DL CC; and performing an operation for
transmitting CSI according to the CSI report mode set on each DL
CC. If a P-number of CSI overlap in the same subframe and a first
condition is satisfied, a Q-number of CSI among the P-number of CSI
are transmitted through a first physical channel, and if the
P-number of SCI overlap in the same subframe and a second condition
is satisfied, only an R-number of CSI among the P-number of CSI are
transmitted through a second physical channel which is different
from the first physical channel, wherein R is smaller than Q.
Inventors: |
Yang; Suckchel (Anyang-si,
KR), Kim; Mingyu (Anyang-si, KR), Ahn;
Joonkui (Anyang-si, KR), Seo; Dongyoun
(Anyang-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG ELECTRONICS INC. (Seoul,
KR)
|
Family
ID: |
47296648 |
Appl.
No.: |
15/590,322 |
Filed: |
May 9, 2017 |
PCT
Filed: |
June 11, 2012 |
PCT No.: |
PCT/KR2012/004598 |
371(c)(1),(2),(4) Date: |
November 25, 2013 |
PCT
Pub. No.: |
WO2012/169859 |
PCT
Pub. Date: |
December 13, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
61495388 |
Jun 10, 2011 |
|
|
|
|
61554478 |
Nov 1, 2011 |
|
|
|
Reissue of: |
14122125 |
Jun 11, 2012 |
9167576 |
Oct 20, 2015 |
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
24/10 (20130101); H04L 1/0026 (20130101); H04L
1/0068 (20130101); H04L 1/0057 (20130101); H04W
72/042 (20130101); H04L 1/0068 (20130101); H04L
1/1671 (20130101); H04L 1/0026 (20130101); H04L
5/001 (20130101); H04L 1/1664 (20130101); H04L
1/1621 (20130101); H04L 1/1671 (20130101); H04W
72/042 (20130101); H04W 24/10 (20130101); H04L
5/0057 (20130101); H04L 1/0057 (20130101); H04L
1/1664 (20130101); H04L 1/1621 (20130101); H04L
5/001 (20130101); H04L 5/0057 (20130101) |
Current International
Class: |
H04W
72/04 (20090101); H04W 4/00 (20180101); H04L
5/00 (20060101); H04W 24/10 (20090101); H04L
1/16 (20060101); H04L 1/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
10-2008-0029912 |
|
Apr 2008 |
|
KR |
|
WO 2010/101409 |
|
Sep 2010 |
|
WO |
|
WO 2011/053970 |
|
May 2011 |
|
WO |
|
Other References
3rd Generation Partnership Project, "Technical Specification Group
Radio Access Network; Evolved Universal Terrestrial Radio Access
(E-UTRA); Physical Layer Procedures (Release 10)," 3GPP TS 36.213,
V10.1.0, Mar. 2011, pp. 1-115. cited by applicant .
CATR, "Periodic CQI Feedback on PUCCH for LTE-A," 3GPP TSG RAN WG1
Meeting #63, R1-106271, Jacksonville, USA, Nov. 15-19, 2010, 2
pages. cited by applicant.
|
Primary Examiner: England; David E
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Claims
The invention claimed is:
1. A method for reporting channel state information (CSI) in a
wireless communication system that supports carrier aggregation,
the method comprising: configuring a plurality of downlink
component carriers (DL CCs); setting a CSI report mode
.[.corresponding to.]. .Iadd.for a respective one of .Iaddend.the
plurality of DL CCs .[.for each DL CC.].; and performing an
operation for transmitting CSI in accordance with the CSI report
mode set .[.corresponding to each DL CC.]. .Iadd.for the respective
one of the plurality of DL CCs.Iaddend., wherein, if a P-number of
CSIs overlap with one another for the same subframe and a first
condition is satisfied, a Q-number of CSIs among the P-number of
CSIs are transmitted through a first physical channel, and if the
P-number of CSIs overlap with one another for the same subframe and
a second condition is satisfied, only an R-number of CSIs among the
P-number of CSI are transmitted through a second physical channel
which is different from the first physical channel, R being smaller
than Q.
2. The method according to claim 1, wherein the first condition
includes that P is equal to or more than M, the second condition
includes that P is less than M, P and Q are the same as each other,
and M is a minimum number of CSIs allowed for simultaneous
transmission through the first physical channel.
3. The method according to claim 1, wherein the first condition
includes that P is more than L, the second condition includes that
P is less than M, P is greater than Q, Q is the same as L, L is a
maximum number of CSIs allowed for simultaneous transmission
through the first physical channel, and M is a minimum number of
CSIs allowed for simultaneous transmission through the first
physical channel.
4. The method according to claim 1, wherein the first condition
includes that a size sum of the P number of CSIs is equal to or
more than M, the second condition includes that a size sum of the P
number of CSIs is less than M, P is the same as Q, R is a number of
CSIs, which has the highest priority among the P number of CSIs and
a size sum of CSIs of maximum integer being equal to or less than
S, M is a minimum size of CSI allowed for simultaneous transmission
through the first physical channel, and S is an integer less than M
determined in accordance with capacity of the second physical
channel.
5. The method according to claim 1, wherein the first condition
includes that a size sum of the P number of CSIs is more than L,
the second condition includes that a size sum of the P number of
CSIs is less than M, P is greater than Q, Q is a number of CSIs,
which has the highest priority among the P number of CSIs and a
size sum of CSIs of maximum integer being equal to or less than L,
R is a number of CSIs, which has the highest priority among the P
number of CSIs and a size sum of CSIs of maximum integer being
equal to or less than S, L is a maximum size of CSI allowed for
simultaneous transmission through the first physical channel, M is
a minimum size of CSI allowed for simultaneous transmission through
the first physical channel, and S is an integer less than M
determined in accordance with capacity of the second physical
channel.
6. A communication apparatus configured to report channel state
information (CSI) in a wireless communication system that supports
carrier aggregation, the communication apparatus comprising: a
radio frequency (RF) unit; and a processor, wherein the processor
configures a plurality of downlink component carriers (DL CCs),
sets a CSI report mode .[.corresponding to.]. .Iadd.for a
respective one of .Iaddend.the plurality of DL CCs .[.for each DL
CC.].; and performs an operation for transmitting CSI in accordance
with the CSI report mode set .[.corresponding to each DL CC.].
.Iadd.for the respective one of the plurality of DL CCs.Iaddend.,
wherein, if a P-number of CSIs overlap with one another for the
same subframe and a first condition is satisfied, a Q-number of
CSIs among the P-number of CSIs are transmitted through a first
physical channel, and if the P-number of CSIs overlap with one
another for the same subframe and a second condition is satisfied,
only an R-number of CSIs among the P-number of CSI are transmitted
through a second physical channel which is different from the first
physical channel, R being smaller than Q.
7. The communication apparatus according to claim 6, wherein the
first condition includes that P is equal to or more than M, the
second condition includes that P is less than M, P and Q are the
same as each other, and M is a minimum number of CSIs allowed for
simultaneous transmission through the first physical channel.
8. The communication apparatus according to claim 6, wherein the
first condition includes that P is more than L, the second
condition includes that P is less than M, P is greater than Q, Q is
the same as L, L is a maximum number of CSIs allowed for
simultaneous transmission through the first physical channel, and M
is a minimum number of CSIs allowed for simultaneous transmission
through the first physical channel.
9. The communication apparatus according to claim 6, wherein the
first condition includes that a size sum of the P number of CSIs is
equal to or more than M, the second condition includes that a size
sum of the P number of CSIs is less than M, P is the same as Q, R
is a number of CSIs, which has the highest priority among the P
number of CSIs and a size sum of CSIs of maximum integer being
equal to or less than S, M is a minimum size of CSI allowed for
simultaneous transmission through the first physical channel, and S
is an integer less than M determined in accordance with capacity of
the second physical channel.
10. The communication apparatus according to claim 6, wherein the
first condition includes that a size sum of the P number of CSIs is
more than L, the second condition includes that a size sum of the P
number of CSIs is less than M, P is greater than Q, Q is a number
of CSIs, which has the highest priority among the P number of CSIs
and a size sum of CSIs of maximum integer being equal to or less
than L, R is a number of CSIs, which has the highest priority among
the P number of CSIs and a size sum of CSIs of maximum integer
being equal to or less than S, L is a maximum size of CSI allowed
for simultaneous transmission through the first physical channel, M
is a minimum size of CSI allowed for simultaneous transmission
through the first physical channel, and S is an integer less than M
determined in accordance with capacity of the second physical
channel.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
.[.This non provisional application is a National Stage entry under
U.S.C. .sctn.371 of International Application No. PCT/KR2012/004598
filed on Jun. 11, 2012, which claims the benefit of U.S.
Provisional Application Nos. 61/495,388 filed on Jun. 10, 2011 and
61/554,478 filed on Nov. 1, 2011. The entire contents of all of the
above applications are hereby incorporated by reference..].
.Iadd.This Application is a Reissue Application of U.S. Pat. No.
9,167,576 issued on Oct. 20, 2015, which was filed as the National
Phase of PCT/KR2012/004598 on Jun. 11, 2012, which claims the
benefit under 35 U.S.C. .sctn. 119(e) to U.S. Provisional
Application Nos. 61/554,478 filed on Nov. 1, 2011 and 61/495,388
filed on Jun. 10, 2011, all of which are hereby expressly
incorporated by reference into the present application.
.Iaddend.
TECHNICAL FIELD
The present invention relates to a wireless communication system,
and more particularly, to a method for transmitting control
information and an apparatus for the same.
BACKGROUND ART
A wireless communication system has been widely developed to
provide various kinds of communication services such as voice and
data. Generally, the wireless communication system is a multiple
access system that can support communication with multiple users by
sharing available system resources (bandwidth, transmission power,
etc.). Examples of the multiple access system include a code
division multiple access (CDMA) system, a frequency division
multiple access (FDMA) system, a time division multiple access
(TDMA) system, an orthogonal frequency division multiple access
(OFDMA) system, and a single carrier frequency division multiple
access (SC-FDMA) system.
DISCLOSURE
Technical Problem
An object of the present invention devised to solve the
conventional problem is to provide a method for efficiently
transmitting control information in a wireless communication system
and an apparatus for the same. Another object of the present
invention is to provide a method for efficiently transmitting
uplink control information (for example, channel state information)
and efficiently managing resources for the uplink control
information in a system in which a plurality of carriers or cells
are aggregated, and an apparatus for the same.
It will be appreciated by persons skilled in the art that the
objects that could be achieved with the present invention are not
limited to what has been particularly described hereinabove and the
above and other objects that the present invention could achieve
will be more clearly understood from the following detailed
description.
Technical Solution
In one aspect of the present invention, a method for reporting
channel state information (CSI) in a wireless communication system
that supports carrier aggregation comprises the steps of
configuring a plurality of downlink component carriers (DL CCs);
setting a CSI report mode on the plurality of DL CCs for each DL
CC; and performing an operation for transmitting CSI in accordance
with the CSI report mode set on each DL CC, wherein, if a P-number
of CSIs overlap with one another for the same subframe and a first
condition is satisfied, a Q-number of CSIs among the P-number of
CSIs are transmitted through a first physical channel, and if the
P-number of CSIs overlap with one another for the same subframe and
a second condition is satisfied, only an R-number of CSIs among the
P-number of CSI are transmitted through a second physical channel
which is different from the first physical channel, R being smaller
than Q.
In another aspect of the present invention, a communication
apparatus configured to report channel state information (CSI) in a
wireless communication system that supports carrier aggregation
comprises a radio frequency (RF) unit; and a processor, wherein the
processor configures a plurality of downlink component carriers (DL
CCs), sets a CSI report mode on the plurality of DL CCs for each DL
CC, and performs an operation for transmitting CSI in accordance
with the CSI report mode set on each DL CC, and if a P-number of
CSIs overlap with one another for the same subframe and a first
condition is satisfied, a Q-number of CSIs among the P-number of
CSIs are transmitted through a first physical channel, and if the
P-number of CSIs overlap with one another for the same subframe and
a second condition is satisfied, only an R-number of CSIs among the
P-number of CSI are transmitted through a second physical channel
which is different from the first physical channel, R being smaller
than Q.
Preferably, the first condition includes that P is more than M, the
second condition includes that P is less than M, P and Q are the
same as each other, and M is the minimum number of CSIs allowed for
simultaneous transmission through the first physical channel.
Preferably, the first condition includes that P is more than L, the
second condition includes that P is less than M, P is greater than
Q, Q is the same as L, L is the maximum number of CSIs allowed for
simultaneous transmission through the first physical channel, and M
is the minimum number of CSIs allowed for simultaneous transmission
through the first physical channel.
Preferably, the first condition includes that a size sum of the P
number of CSIs is more than M, the second condition includes that a
size sum of the P number of CSIs is less than M, P is the same as
Q, R is the number of CSIs, which has the highest priority among
the P number of CSIs and a size sum of CSIs of maximum integer less
than S, M is a minimum size of CSI allowed for simultaneous
transmission through the first physical channel, and S is an
integer less than M determined in accordance with capacity of the
second physical channel.
Preferably, the first condition includes that a size sum of the P
number of CSIs is more than L, the second condition includes that a
size sum of the P number of CSIs is less than M, P is greater than
Q, Q is the number of CSIs, which has the highest priority among
the P number of CSIs and a size sum of CSIs of maximum integer less
than L, R is the number of CSIs, which has the highest priority
among the P number of CSIs and a size sum of CSIs of maximum
integer less than S, L is a maximum size of CSI allowed for
simultaneous transmission through the first physical channel, M is
a minimum size of CSI allowed for simultaneous transmission through
the first physical channel, and S is an integer less than M
determined in accordance with capacity of the second physical
channel.
Advantageous Effects
According to the present invention, control information may
efficiently be transmitted in the wireless communication system. In
more detail, uplink control information (for example, channel state
information) may efficiently be transmitted in a system where a
plurality of carriers or cells are aggregated, and resources for
the uplink control information may be managed efficiently.
It will be appreciated by persons skilled in the art that that the
effects that could be achieved with the present invention are not
limited to what has been particularly described hereinabove and
other advantages of the present invention will be more clearly
understood from the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
FIG. 1 is a diagram illustrating physical channels used in a 3GPP
system and a general method for transmitting a signal using the
physical channels;
FIG. 2 is a diagram illustrating a structure of a radio frame;
FIG. 3 is a diagram illustrating a resource grid of a downlink
slot;
FIG. 4 is a diagram illustrating a structure of a downlink
subframe;
FIG. 5 is a diagram illustrating a structure of an uplink
subframe;
FIG. 6 is a diagram illustrating a structure of a slot level of
PUCCH formats 1/1a/1b;
FIG. 7 is a diagram illustrating a structure of a slot level of
PUCCH formats 2/2a/2b;
FIGS. 8 to 11 are diagrams illustrating periodic report of channel
state information on a single carrier or cell;
FIG. 12 is a diagram illustrating a carrier aggregation (CA)
communication system;
FIG. 13 is a diagram illustrating cross-carrier scheduling;
FIGS. 14 and 15 are diagrams illustrating an enhanced-PUCCH
(E-PUCCH) format (that is, PUCCH format 3);
FIG. 16 is a diagram illustrating a procedure of CSI report
according to the related art when a plurality of carriers or cells
are aggregated;
FIG. 17 is a diagram illustrating a procedure of CSI report
according to the embodiment of the present invention when a
plurality of carriers or cells are aggregated; and
FIG. 18 is a diagram illustrating a base station and a user
equipment, which can be applied to one embodiment of the present
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
The following technology may be used for various wireless access
technologies such as CDMA (code division multiple access), FDMA
(frequency division multiple access), TDMA (time division multiple
access), OFDMA (orthogonal frequency division multiple access), and
SC-FDMA (single carrier frequency division multiple access). The
CDMA may be implemented by the radio technology such as UTRA
(universal terrestrial radio access) or CDMA2000. The TDMA may be
implemented by the radio technology such as global system for
mobile communications (GSM)/general packet radio service
(GPRS)/enhanced data rates for GSM evolution (EDGE). The OFDMA may
be implemented by the radio technology such as IEEE 802.11 (Wi-Fi),
IEEE 802.16 (WiMAX), IEEE 802.20, and evolved UTRA (E-UTRA). The
UTRA is a part of a universal mobile telecommunications system
(UMTS). A 3.sup.rd generation partnership project long term
evolution (3GPP LTE) is a part of an evolved UMTS (E-UMTS) that
uses E-UTRA, and adopts OFDMA in a downlink and SC-FDMA in an
uplink. LTE-advanced (LTE-A) is an evolved version of the 3GPP
LTE.
For clarification of the description, the following embodiments
will be described based on that technical features of the present
invention are applied to the 3GPP LTE/LTE-A. However, it is to be
understood that the technical spirits of the present invention are
not limited to the 3GPP LTE/LTE-A. Also, specific terminologies
used hereinafter are provided to assist understanding of the
present invention, and various modifications may be made in the
specific terminologies within the range that does not depart from
the technical spirits of the present invention.
In a wireless communication system, a user equipment receives
information from a base station through a downlink (DL), and also
transmits information to the base station through an uplink (UL).
Examples of information transmitted from or received in the base
station and the user equipment include data and various kinds of
control information, and various physical channels exist depending
on a type and usage of the information transmitted from or received
in the base station and the user equipment.
FIG. 1 is a diagram illustrating physical channels used in a 3GPP
LTE system and a general method for transmitting a signal using the
physical channels.
The user equipment performs initial cell search such as
synchronizing with the base station when it newly enters a cell or
the power is turned on at step S101. To this end, the user
equipment synchronizes with the base station by receiving a primary
synchronization channel (P-SCH) and a secondary synchronization
channel (S-SCH) from the base station, and acquires information
such as cell ID, etc.
Afterwards, the user equipment may acquire broadcast information
within the cell by receiving a physical broadcast channel (PBCH)
from the base station. Meanwhile, the user equipment may identify a
downlink channel status by receiving a downlink reference signal
(DL RS) at the initial cell search step.
The user equipment which has finished the initial cell search may
acquire more detailed system information by receiving a physical
downlink shared channel (PDSCH) in accordance with a physical
downlink control channel (PDCCH) and information carried in the
PDCCH at step S102.
Afterwards, the user equipment may perform a random access
procedure (RACH) such as steps S103 to S106 to complete access to
the base station. To this end, the user equipment may transmit a
preamble through a physical random access channel (PRACH) (S103),
and may receive a response message to the preamble through the
PDCCH and the PDSCH corresponding to the PDCCH (S104). In case of a
contention based RACH, the user equipment may perform a contention
resolution procedure such as transmission (S105) of additional
physical random access channel and reception (S106) of the physical
downlink control channel and the physical downlink shared channel
corresponding to the physical downlink control channel.
The user equipment which has performed the aforementioned steps may
receive the physical downlink control channel (PDCCH)/physical
downlink shared channel (PDSCH) (S107) and transmit a physical
uplink shared channel (PUSCH) and a physical uplink control channel
(PUCCH) (S108), as a general procedure of transmitting
uplink/downlink signals. Control information transmitted from the
user equipment to the base station will be referred to as uplink
control information (UCI). The UCI includes HARQ ACK/NACK (Hybrid
Automatic Repeat and reQuest Acknowledgement/Negative-ACK), SR
(Scheduling Request), CQI (Channel Quality Information), a PMI
(Precoding Matrix Indicator), RI (Rank Indication), etc. Although
the UCI is periodically transmitted through the PUCCH in the LTE
system, it may be transmitted through the PUSCH if control
information and traffic data should be transmitted at the same
time. Also, the user equipment may non-periodically transmit the
UCI through the PUSCH in accordance with request/command of the
network.
FIG. 2 is a diagram illustrating a structure of a radio frame. The
radio frame includes a plurality of subframes, each of which
includes a plurality of OFDM or SC-FDMA symbols. The 3GPP LTE(-A)
standard supports a type 1 radio frame structure for frequency
division duplex (FDD) and a type 2 radio frame structure for time
division duplex (TDD).
FIG. 2(a) is a diagram illustrating a structure of a type 1 radio
frame. The downlink radio frame includes 10 subframes, each of
which includes two slots in a time domain. For example, one
subframe may have a length of 1 ms, and one slot may have a length
of 0.5 ms. One slot includes a plurality of OFDM symbols or a
plurality of SC-FDMA symbols in a time domain, and includes a
plurality of resource blocks (RBs) in a frequency domain. The 3GPP
LTE(-A) system uses OFDMA on a downlink and SC-FDMA on an
uplink.
FIG. 2(b) is a diagram illustrating a structure of a type 2 radio
frame. The type 2 radio frame includes two half frames, each of
which includes four normal subframes and one special subframe. The
special subframe includes a downlink pilot time slot (DwPTS), a
guard period (GP), and an uplink pilot time slot (UpPTS). The DwPTS
is used for initial cell search, synchronization or channel
estimation at the user equipment. The UpPTS is used to synchronize
channel estimation at the base station with uplink transmission of
the user equipment. Also, the guard period provides switching time
between UL transmission and DL transmission. Each normal subframe
within the radio frame is used for UL transmission or DL
transmission in accordance with uplink-downlink (UL-DL)
configuration.
FIG. 3 is a diagram illustrating a resource grid of a downlink
slot. A structure of an uplink slot is the same as that of the
downlink slot except that OFDM symbols are replaced with SC-FDMA
symbols.
Referring to FIG. 3, the downlink slot includes a plurality of OFDM
symbols in a time domain. The downlink slot may include seven (six)
OFDM symbols, and a resource block may include twelve subcarriers
in a frequency domain. Each element on the resource grid will be
referred to as a resource element (RE). One resource block (RB)
includes 12.times.7(6) resource elements. The number N.sub.RB of
resource blocks (RBs) included in the downlink slot depends on a
downlink transmission bandwidth.
FIG. 4 is a diagram illustrating a structure of a downlink
subframe.
Referring to FIG. 4, maximum three (four) OFDM symbols located at
the front of the first slot of the subframe correspond to a control
region to which a control channel is allocated. The other OFDM
symbols correspond to a data region to which a physical downlink
shared channel (PDSCH) is allocated. Examples of the downlink
control channel used in the LTE include a PCFICH (Physical Control
Format Indicator CHannel), a PDCCH (Physical Downlink Control
CHannel), and a PHICH (Physical Hybrid ARQ Indicator CHannel). The
PCFICH is transmitted at the first OFDM symbol of the subframe, and
carries information on the number of OFDM symbols used for
transmission of the control channel within the subframe. The PHICH
carries HARQ ACK/NACK (acknowledgement/negative-acknowledgement)
signal in response to uplink transmission. The PDCCH carries
transport format and resource allocation information of a downlink
shared channel (DL-SCH), transport format and resource allocation
information of an uplink shared channel (UL-SCH), paging
information on a paging channel (PCH), system information on the
DL-SCH, resource allocation information of upper layer control
message such as random access response transmitted on the PDSCH, a
set of transmission power control commands of individual user
equipments (UEs) within a user equipment group, a transmission
power control command, activity indication information of voice
over Internet protocol (VoIP), etc.
FIG. 5 is a diagram illustrating a structure of an uplink subframe
in an LTE system.
Referring to FIG. 5, the uplink subframe includes a plurality of
slots (for example, two). Each slot may include a plurality of
SC-FDMA symbols, wherein the number of SC-FDMA symbols included in
each slot is varied depending on a cyclic prefix (CP) length. The
uplink subframe is divided into a data region and a control region
in a frequency domain. The data region includes a PUSCH, and is
used to transmit a data signal such as voice. The control region
includes a PUCCH, and is used to transmit uplink control
information (UCI). The PUCCH includes RB pair located at both ends
of the data region on a frequency axis, and performs hopping on the
border of the slots.
The PUCCH may be used to transmit the following control
information. SR (Scheduling Request): is information used to
request uplink UL-SCH resource. The SR is transmitted using an
on-off keying (OOK) system. HARQ ACK/NACK: is a response signal to
a downlink data packet on the PDSCH. It represents whether the
downlink data packet has been successfully received. ACK/NACK 1 bit
is transmitted in response to a single downlink codeword (CW), and
ACK/NACK 2 bits are transmitted in response to two downlink
codewords. CSI (Channel State Information): is feedback information
on a downlink channel. The CSI includes a channel quality indicator
(CQI), a rank indicator (RI), a precoding matrix indicator (PMI),
and a precoding type indicator (PTI). 20 bits are used per
subframe.
The quantity of the uplink control information (UCI) that may be
transmitted from the user equipment for the subframe depends on the
number of SC-FDMA symbols available for control information
transmission. The SC-FDMA symbols available for control information
transmission mean the remaining SC-FDMA symbols except for SC-FDMA
symbols for reference signal transmission for the subframe, and the
last SC-FDMA symbol of the subframe is excluded in case of the
subframe for which a sounding reference signal (SRS) is set. The
reference signal is used for coherent detection of the PUCCH. The
PUCCH supports seven formats in accordance with information which
is transmitted.
Table 1 illustrates a mapping relation between the PUCCH format and
the UCI in the LTE(-A) system.
TABLE-US-00001 TABLE 1 PUCCH format Uplink control information
(UCI) Format 1 SR (Scheduling Request) (non-modulated waveform)
Format 1a 1-bit HARQ ACK/NACK with/without SR Format 1b 2-bit HARQ
ACK/NACK with/without SR Format 2 CSI (20 coded bits) Format 2 CSI
and 1- or 2-bit HARQ ACK/NACK (20 bits) for extended CP only Format
2a CSI and 1-bit HARQ ACK/NACK (20 + 1 coded bits) Format 2b CSI
and 2-bit HARQ ACK/NACK (20 + 2 coded bits) Format 3 HARQ ACK/NACK
(+SR) (48 bits) (LTE-A)
Since the LTE user equipment cannot transmit the PUCCH and the
PUSCH at the same time, if UCI (for example, CQI/PMI, HARQ-ACK, RI,
etc.) transmission is required for the subframe for which the PUSCH
is transmitted, the user equipment multiplexes the UCI in the PUSCH
region. For example, if the user equipment should transmit HARQ-ACK
for the subframe for which PUSCH transmission is allocated, the
user equipment multiplexes UL-SCH data and HARQ-ACK before
DFT-spreading and then transmits control information and data
through the PUSCH.
FIG. 6 is a diagram illustrating a structure of a slot level of
PUCCH formats 1/1a/1b. The PUCCH format 1 is used for SR
transmission, and the PUCCH formats 1a/1b are used for ACK/NACK
transmission. In case of normal CP, SC-FDMA #2/#3/#4 are used for
transmission of DM RS (Demodulation Reference Signal). In case of
extended CP, SC-FDMA #2/#3 are used for transmission of DM RS.
Referring to FIG. 6, ACK/NACK information of 1 bit and ACK/NACK
information of 2 bits are respectively modulated in accordance with
a binary phase shift keying (BPSK) modulation scheme and a
quadrature phase shift keying (QPSK) modulation scheme, and one
ACK/NACK modulation symbol (d.sub.0) is generated. The ACK/NACK
information is set to 1 in case of positive ACK, whereas the
ACK/NACK information is set to 0 in case of negative ACK (NACK). A
cyclic shift (CS) (.alpha..sub.cs,x) is applied to the PUCCH
formats 1a/1b in the frequency domain, and orthogonal spreading
codes (for example, Walsh-Hadamard or DFT codes)
w.sub.0,w.sub.1,w.sub.2,w.sub.3 are applied thereto in the time
time domain. In case of the PUCCH formats 1a/1b, since code
multiplexing is used in both the frequency domain and the time
domain, more user equipments may be multiplexed on the same PUCCH
RB.
The RS transmitted from different user equipments are multiplexed
using the same method as that of the UCI. The number of cyclic
shifts supported by the SC-FDMA symbols for PUCCH ACK/NACK RB may
be configured by a cell-specific higher layer signaling parameter
.DELTA..sub.shift.sup.PUCCH. .DELTA..sub.shift.sup.PUCCH .di-elect
cons.{1, 2, 3} represents that shift values are 12, 6 and 4,
respectively. The number of spreading codes that may actually be
used for ACK/NACK in time-domain CDM may be limited by the number
of RS symbols. This is because that multiplexing capacity of the RS
symbols is smaller than that of UCI symbols due to a small number
of RS symbols.
FIG. 7 is a diagram illustrating a structure of a slot level of
PUCCH formats 2/2a/2b. The PUCCH formats 2/2a/2b are used for CSI
(channel state information) transmission. The CSI includes CQI,
PMI, RI, etc. In case of normal cyclic prefix (CP), SC-FDMA #1 and
#5 are used for transmission of demodulation reference signal (DM
RS) within the slot. In case of extended CP, SC-FDMA symbol (LB) #3
is only used for transmission of the DM RS within the slot.
Referring to FIG. 7, CCI of 10 bits is channel coded to 20 coded
bits using rate 1/2 punctured (20, k) Reed-Muller codes at a
subframe level (not shown). Afterwards, the coded bits are mapped
into quadrature phase shift keying (QPSK) constellation (QPSK
modulation) through scramble (not shown). Scramble may be performed
using length-31 gold sequence similarly to PUSCH data. Ten QPSK
modulation symbols are generated and five QPSK modulation symbols
d.sub.0.about.d.sub.4 are transmitted from each slot through
corresponding SC-FDMA symbols. Each of the QPSK modulation symbols
is used to modulate a length-12 base RS sequence (r.sub.u,O) prior
to inverse fast fourier transform (IFFT). Consequently, the RS
sequence is cyclic-shifted in the time domain in accordance with
the values of the QPSK modulation symbols (d.sub.x*r.sub.u,O,
x=0.about.4). The RS sequence multiplied by the QPSK modulation
symbols is cyclic-shifted (.alpha..sub.cs,x, x=1, 5). If the number
of cyclic shifts is N, N number of user equipments may be
multiplexed on the same CSI PUCCH RB.
FIGS. 8 to 11 are diagrams illustrating periodic report of channel
state information on a single carrier or cell. In other words,
FIGS. 8 to 11 illustrate periodic report of channel state
information on a single carrier or cell. Parameters/resources for
periodic report of the CSI (for example, CQI) are configured
semi-statically by higher layer (for example, RRC (radio resource
control)) signaling. For example, if a PUCCH resource index
n.sub.PUCCH.sup.(2) is set for CSI transmission, the CSI is
transmitted periodically on a CSI PUCCH linked with the PUCCH
resource index n.sub.PUCCH.sup.(2). The PUCCH resource index
n.sub.PUCCH.sup.(2) indicates cyclic shift (.alpha..sub.cs) and
PUCCH RB.
Referring to FIG. 8, four types of CQI report modes exist in the
LTE system. In more detail, the CQI report modes may be divided
into a wideband (WB) CQI report mode and a subband (SB) CQI mode in
accordance with CQI feedback type, and may be divided into a
non-PMI report mode and a single PMI report mode in accordance with
PMI transmission. Each user equipment receives information obtained
by combination of period and offset through RRC signaling to
periodically report CQI.
FIG. 9 illustrates an example of channel state information
transmitted if information indicating {period `5`, offset `1`} is
signaled to the user equipment. Referring to FIG. 9, if information
indicating a period of `5` and offset of `1` is signaled to the
user equipment, the user equipment transmits the channel state
information in a unit of five subframes at offset of a subframe in
an increasing direction of subframe index from the 0.sup.th
subframe. Although the channel state information is basically
transmitted through the PUCCH, if the PUSCH for data transmission
exists at the same time, the channel state information is
transmitted together with data through the PUSCH. The subframe
index is comprised by combination of system frame number n.sub.f
and slot index (n.sub.s, 0.about.19). Since the subframe includes
two slots, the subframe index may be defined as
10*n.sub.f+floor(n.sub.s/2). floor( )represents a floor
function.
There exist a type for transmitting WB CQI only and a type for
transmitting both WB CQI and SB CQI. In case of the type for
transmitting WB CQI only, CQI for the entire band is transmitted
for a subframe corresponding to every CQI transmission period.
Meanwhile, as shown in FIG. 8, if PMI should be transmitted in
accordance with a PMI feedback type, PMI information is transmitted
together with CQI. In case of the type for transmitting WB CQI and
SB CQI, WB CQI and SB CQI are transmitted alternately.
FIG. 10 illustrates a system of which system band includes 16 RBs.
In this case, it is assumed that the system band includes two
bandwidth parts (BPs) (BP0, BP1), each of which includes two
subbands (SBs) (SB0, SB1), each of which includes four RBs. This
assumption is exemplary for description, wherein the number of BPs
and a size of each BP may be varied depending on the size of the
system band. Also, the number of SBs constituting each BP may be
varied depending on the number of RBs, the number of BPs and the
size of the SB.
In case of the type for transmitting both WB CQI and SB CQI, WB CQI
is transmitted for the first CQI transmission subframe, and CQI of
SB having good channel status from SB0 and SB1, which belong to
BP0, and index of the corresponding SB are transmitted for next CQI
transmission subframe. Afterwards, CQI of SB having good channel
status from SB0 and SB1, which belong to BP1, and index of the
corresponding SB are transmitted for next CQI transmission
subframe. In this way, after WB CQI is transmitted, CQI for each BP
is transmitted in due order. CQI for each BP may be transmitted in
due order once to four times between two WB CQIs. For example, if
CQI is transmitted in due order once between two WB CQIs, the CQI
may be transmitted in the order of WB CQI BP0 CQI BP1 CQI WB CQI.
Also, if CQI is transmitted in due order four times between two WB
CQIs, the CQI may be transmitted in the order of WB CQI BP0 CQI BP1
CQI BP0 CQI BP1 CQI BP0 CQI BP1 CQI BP0 CQI BP1 CQI WB CQI.
Information as to how many times CQI for each BP is transmitted in
due order is signaled from a higher layer (for example, RRC
layer).
FIG. 11(a) illustrates that both WB CQI and SB CQI are transmitted
if information indicating {period of `5`, offset of `1`} is
signaled to the user equipment. Referring to FIG. 11(a), CQI may be
transmitted for the subframe only corresponding to the signaled
period and offset regardless of a type. FIG. 11(b) illustrates that
RI is additionally transmitted in case of FIG. 11(a). RI may be
signaled from the higher layer (for example, RRC layer) by
combination of a transmission period indicating what multiple of WB
CQI transmission period is used to transmit RI and offset at the
transmission period of RI. Offset of RI is signaled at a relative
value of offset of CQI. For example, if offset of CQI is `1` and
offset of RI is `0`, RI has the same offset as that of CQI. The
offset of RI is defined by 0 and a value of a negative number. In
more detail, in FIG. 11(b), it is assumed that the transmission
period of RI is one time of the transmission period of WB CQI and
the offset of RI is `-1` in the same environment as that of FIG.
11(a). Since the transmission period of RI is one time of the
transmission period of WB CQI, the transmission period of the
channel state information is substantially the same. Since the
offset of RI is `-1`, RI is transmitted on the basis of `-1` (that
is, 0.sup.th subframe) for offset `1` of CQI in FIG. 11(a). If the
offset of RI is `0`, transmission subframes of WB CQI and RI are
overlapped with each other. In this case, WB CQI is dropped and RI
is transmitted.
FIG. 12 is a diagram illustrating a carrier aggregation (CA)
communication system. The LTE-A system uses the carrier aggregation
technology or the bandwidth aggregation technology, which uses
greater uplink/downlink bandwidth through a plurality of
uplink/downlink frequency blocks, to use wider frequency bandwidth.
Each frequency block is transmitted using a component carrier (CC).
The component carrier may be understood as carrier frequency (or
center carrier or center frequency) for a corresponding frequency
block.
Referring to FIG. 12, a plurality of uplink/downlink component
carriers (CC) may be collected to support wider uplink/downlink
bandwidth. The respective CCs may adjoin each other or not in the
frequency domain. A bandwidth of each component carrier may be
defined independently. Asymmetric carrier aggregation where the
number of UL CCs is different from the number of DL CCs may be
performed. For example, if the number of DL CCs is 2 and the number
of UL CCs is 1, carrier aggregation may be configured to correspond
to 2:1. DL CC/UL CC links may be fixed to the system or may be
configured semi-statically. Also, even though a system full band
includes N number of CCs, a frequency band that may be monitored
and received by a specific user equipment may be limited to
M(<N) number of CCs. Meanwhile, the control information may be
set to be transmitted and received through a specific CC only. This
specific CC may be referred to as a primary CC (PCC) (or anchor
CC), and the other CCs may be referred to as secondary CCs
(SCC).
The LTE-A system uses a concept of cell to manage radio resources.
The cell is defined by combination of downlink resources and uplink
resources, wherein the uplink resources may be defined selectively.
Accordingly, the cell may be configured by downlink resources only,
or may be configured by downlink resources and uplink resources. If
carrier aggregation is supported, linkage between carrier frequency
(or DL CC) of the downlink resources and carrier frequency (or UL
CC) of the uplink resources may be indicated by system information.
The cell operated on the primary frequency (or PCC) may be referred
to as a primary cell (PCell), and the cell operated on the
secondary frequency (or SCC) may be referred to as a primary cell
(PCell). The PCell is used such that the user equipment performs an
initial connection establishment procedure or connection
re-establishment procedure. The PCell may refer to a cell indicated
during a handover procedure. The Scell may be configured after RRC
connection is established, and may be used to provide an additional
radio resource. The Pcell and the Scell may be referred to as
serving cells. Accordingly, although the user equipment is in
RRC-CONNECTED state, if it is not set by carrier aggregation or
does not support carrier aggregation, a single serving cell
configured by the P cell only exists. On the other hand, if the
user equipment is in the RRC-CONNECTED state and is set by carrier
aggregation, one or more serving cells may exist, wherein the
serving cells may include the Pcell and full Scells. After an
initial security activity procedure starts, for the user equipment
supporting carrier aggregation, the network may configure one or
more Scells in addition to the Pcell initially configured during a
connection establishment procedure.
If cross-carrier scheduling (or cross-CC scheduling) is used, the
PDCCH for downlink allocation is transmitted to DL CC#0, and the
corresponding PDSCH may be transmitted to DL CC#2. For
cross-carrier scheduling, the introduction of a carrier indicator
field (CIF) may be considered. The presence of CIF within the PDCCH
may be configured by higher layer signaling (for example, RRC
signaling) semi-statically so and user equipment-specifically. The
base lines of PDCCH transmission will be summed up as follows. CIF
disabled: the PDCCH on the DL CC allocates PDSCH resource on the
same DL CC or PUSCH resource on one linked UL CC. CIF enabled: the
PDCCH on the DL CC may allocate PDSCH or PUSCH resource on a
specific DL/UL CC among a plurality of aggregated DL/UL CCs by
using the CIF.
If the CIF exists, the base station may allocate a PDCCH monitoring
DL cell set to reduce complexity of blind decoding (BD) in view of
the user equipment. The PDCCH monitoring DL cell set includes one
or more DL CCs as a part of the aggregated DL CCs, and the user
equipment detects and decodes the PDCCH on the corresponding DL CC
only. In other words, if the base station schedules the PDSCH/PUSCH
to the user equipment, the PDCCH is transmitted through the PDCCH
monitoring DL CC set only. The PDCCH monitoring DL CC set may be
configured user equipment-specifically, user equipment
group-specifically or cell-specifically. The terms "PDCCH
monitoring DL CC" may be replaced with the equivalent terms such as
monitoring carrier and monitoring cell. Also, the CCs aggregated
for the user equipment may be replaced with the equivalent terms
such as serving CCs, serving carriers, and serving cells.
FIG. 13 is a diagram illustrating scheduling when a plurality of
carriers are aggregated. It is assumed that three DL cells are
aggregated. It is also assumed that DL CC A is set to a PDCCH
monitoring DL CC. DL CC A to DL CC C may be referred to as serving
CCs, serving carriers, serving cells, etc. If the CIF is disabled,
each DL CC may transmit the PDCCH only that schedules PDSCH of the
DL CC without CIF in accordance with the LTE PDCCH rule. On the
other hand, if the CIF is enabled, the DL CC A (monitoring DL CC)
may transmit the PDCCH, which schedules the PDSCH of another CC, as
well as the PDCCH, which schedules the PDSCH of the DL CCA. In this
case, the PDCCH is not transmitted from the DL CC B/C which is not
set to the PDCCH monitoring DL CC.
In the LTE-A system, a new type enhanced PUCCH format (E-PUCCH
format) (that is, PUCCH format 3) has been introduced for
transmission of more ACK/NACK signals.
FIG. 14 is a diagram illustrating E-PUCCH format (that is, PUCCH
format 3) of a slot level. A plurality of kinds of ACK/NACK
information is transmitted through joint coding (for example,
Reed-Muller code, Tail-biting convolutional code, etc.),
block-spreading and SC-FDMA modulation.
Referring to FIG. 14, one symbol sequence is transmitted over the
frequency domain, and orthogonal cover code (OCC) based time-domain
spreading is applied to the corresponding symbol sequence. Control
signals of several user equipments may be multiplexed into the same
RB by using the OCC. In more detail, five SC-FDMA symbols (that is,
UCI data part) are generated from one symbol sequence {d1, d2, . .
. } by using OCCs C1 to C5 of a length-5 (SF (spreading factor)=5).
In this case, the symbol sequence {d1, d2, . . . } may mean a
modulation symbol sequence or codeword bit sequence. If the symbol
sequence {d1, d2, . . . } means a codeword bit sequence, the block
diagram of FIG. 9 further includes a modulation block. Although a
total of two RS symbols (that is, RS part) are used for one slot in
the drawing, various applications may be considered in such a
manner that RS part of three RS symbols is used and UCI data part
based on OCC of SF=4 is used. In this case, the RS symbols may be
generated from constant amplitude zero autocorrelation (CAZAC)
sequences having a specific cyclic shift. Also, the RS may be
transmitted in a format in which a specific OCC is applied to
(multiplied by) a plurality of RS symbols of the time domain.
FIG. 15 illustrates E-PUCCH format (that is, PUCCH format 3) at a
subframe level.
Referring to FIG. 15, symbol sequences {d'0 to d'11} in a slot 0
are mapped into subcarrier of one SC-FDMA symbol and mapped into
five SC-FDMA symbols by block-spreading based on OCCs C1 to C5.
Similarly, symbol sequences {d'12 to d'23} in a slot 1 are mapped
into subcarrier of one SC-FDMA symbol and mapped into five SC-FDMA
symbols by block-spreading based on OCCs C1 to C5. In this case,
the symbol sequences {d'0 to d'11} or the symbol sequences {d'12 to
d'23} shown in each slot represent the format in which FFT or
FFT/IFFT is applied to the symbol sequences {d1, d2, . . . } of
FIG. 10. If the symbol sequences {d'0 to d'11} or {d'12 to d'23}
corresponds to the format in which FFT is applied to the symbol
sequences {d1, d2, . . . } of FIG. 9, IFFT is additionally applied
to the symbol sequences {d'0 to d'11} or {d'12 to d'23} to generate
SC-FDMA symbols. The total symbol sequences {d'0 to d'23} are
generated by joint coding of one or more UCI, and the first half
{d'0 to d'11} is transmitted through the slot 0, and the other half
{d'12 to d'23} is transmitted through the slot 1. Although not
shown, the OCC may be varied in a unit of slot, and UCI data may be
scrambled in a unit of SC-FDMA symbol.
FIG. 16 is a diagram illustrating a procedure of CSI report
according to the related art when a plurality of carriers or cells
are aggregated.
Referring to FIG. 16, the LTE-A supports aggregation of a plurality
of CCs (or cells) (see FIG. 13) (S1602), and a periodic CSI report
mode may be set independently per CC (for example, in accordance
with transmission mode) (S1604). Under the circumstances, if CSI
report subframes are overlapped with one another in the plurality
of CCs (S1606), (regardless of transmis sion based on PUCCH formats
2/2a/2b or transmission based on piggyback to the PUSCH) CSI for a
specific one of the plurality of CCs is only transmitted through
the corresponding subframe, and CSI for the other CCs is dropped
(S1608). One CSI (or one CC which will be a target for CSI
transmission) which will be a target for transmission may be
determined through Step 1 or Step 2 as follows.
Step 1) If only one CSI (CC) has the highest CSI type priority,
corresponding CSI (for CC) is only transmitted.
Step 2) If a plurality of CSI (CC) have the highest CSI type
priority, CSI for CC having the lowest ServCellIndex of the
plurality of CCs is only transmitted.
In this case, the CSI type is given as follows, and the priority
may be given in the order of CSI type 3, 5, 6, 2a (that is,
1.sup.st CSI type)>CSI type 2, 2b, 2c, 4 (that is, r.sup.nd CSI
type)>CSI type 1, 1a (that is, 3.sup.rd CSI type). Type 1 report
supports CQI feedback for the UE selected sub-bands Type 1a report
supports subband CQI and second PMI feedback Type 2, Type 2b, and
Type 2c report supports wideband CQI and PMI feedback Type 2a
report supports wideband PMI feedback Type 3 report supports RI
feedback Type 4 report supports wideband CQI Type 5 report supports
RI and wideband PMI feedback Type 6 report supports RI and PTI
feedback
In the meantime, CSI transmission timing points are not overlapped
with each other at two or more CCs (that is, if CSI transmission
for one CC is required for the corresponding subframe), CSI for the
corresponding CC is transmitted through the corresponding subframe
(S1610).
If periodic CSI report for the plurality of CCs is performed
through the aforementioned related art method, resources (that is,
overhead) required for CSI transmission may be reduced. However, a
problem may occur in accuracy and efficiency of channel estimation
and scheduling due to dropped CSIs in a state that CSI report
subframes for the plurality of CCs are overlapped with one another.
In this respect, there may be considered a method for
simultaneously transmitting a plurality of CSIs for a plurality of
CCs by using UL channel/format, which may support payload
relatively greater than that of the existing PUCCH formats 2/2a/2b.
For convenience, UL channel/format for transmission of a plurality
of CSIs will be referred to as UL channel/format X. The UL
channel/format may be, but not limited to, PUSCH or PUCCH format 3,
or new UL channel/format which is similar to the PUSCH or PUCCH
format 3. Hereinafter, unless mentioned specifically, the UL
channel/format X may be used to refer to the PUSCH or PUCCH format
3. Resources for the UL channel/format X may previously be
allocated to the user equipment through higher layer signaling (for
example, RRC signaling). Meanwhile, if CSI transmission is
performed using the UL channel/format X (for example, PUSCH or
PUCCH format 3 for transmission of a plurality of CSIs) without
considering the number/amount of CSIs to be transmitted and CSI
type, efficiency in use of UL resources may be reduced.
Accordingly, the present invention suggests a method for
simultaneously transmitting a plurality of CSIs for a plurality of
CCs on the basis of PUSCH or PUCCH format 3 (simply referred to as
PUSCH or PUCCHF3) by considering the number/amount of CSIs of which
transmission is required through CSI report subframe, CSI type, UL
data, and ACK/NACK. For convenience, it is assumed that the
priority based on the CSI type which is used is given by the order
of CSI type 3, 5, 6, 2a (that is, 1.sup.st CSI type)>CSI type 2,
2b, 2c, 4 (that is, 2.sup.nd CSI type)>CSI type 1, 1a (that is,
3.sup.rd CSI type), as described with reference to FIG. 16.
However, this priority is exemplary, and the CSI type applied to
the present invention and the CSI priority based on the CSI type
may be varied depending on the communication environment. The CSI
type applied to the present invention and the CSI priority based on
the CSI type may include, but not limited to, a CSI type of a
specific use such as cooperative multi-point (CoMP) CSI feedback
and a CSI priority corresponding to the CoMP CSI feedback.
Method 1: Limitation of the Number of CSIs (the Number of CCs for
CSI Transmission) which are Simultaneously Transmitted
For example, the number of minimum CSIs (CCs), which may be
transmitted using PUSCH or PUCCHF3, may be limited to M. In this
case, if the number of CSIs (CCs) of which transmission is required
through CSI report subframe is N.sub.CSI, the following operation
may be defined. For example, M may be, but not limited to, 2
(M=2).
i) In case of N.sub.CSI.gtoreq.M (CSI initially transmitted under
the corresponding condition will be referred to as "CSI 1-1")
simultaneous transmission of the corresponding N.sub.CSI CSIs (for
CCs) by using PUSCH or PUCCHF3.
ii) In case of N.sub.CSI<M (CSI initially transmitted under the
corresponding condition will be referred to as "CSI 1-2") one CSI
(for CC) determined on the basis of Step 1 or 2 is only transmitted
using PUCCH formats 2/2a/2b, or all the CSIs are dropped (in this
case, separate PUCCH format 2/2a/2b allocation may not be
required).
For another example, the number of maximum CSIs (CCs), which may be
transmitted using PUSCH or PUCCHF3, may be limited to L. In this
case, the following operation may be defined in accordance with
N.sub.CSI.
i) In case of N.sub.CSI.ltoreq.L simultaneous transmission of the
corresponding N.sub.CSI CSIs (for CCs) by using PUSCH or
PUCCHF3.
ii) In case of N.sub.CSI>L transmission of L number of CSIs (for
CCs) having the highest priority using PUSCH or PUCCHF3 on the
basis of Step 1 or 2
For another example, the number of minimum and maximum CSIs, which
may be transmitted using PUSCH or PUCCHF3 by combination of the
above two methods, may be limited to M and L, respectively. In this
case, the following operation may be defined.
i) In case of N.sub.CSI>L transmission of L number of CSIs (for
CCs) having the highest priority using PUSCH or PUCCHF3 on the
basis of Step 1 or 2
ii) In case of L.gtoreq.N.sub.CSI.gtoreq.M simultaneous
transmission of the corresponding N.sub.CSI CSIs (for CCs) by using
PUSCH or PUCCHF3
iii) N.sub.CSI<M one CSI (for CC) determined on the basis of
Step 1 or 2 is only transmitted using PUCCH formats 2/2a/2b, or all
the CSIs are dropped (in this case, separate PUCCH format 2/2a/2b
allocation may not be required).
In this case, the parameters M and L may be set UE-commonly or
UE-specifically through broadcast or layer 1 (L1)/layer 2
(L2)/radio resource control (RRC) signaling.
The aforementioned description illustrates that CSI transmission is
performed using two types of physical channels. Similarly, the CSI
transmission channels may be determined in the order of PUCCH
formats 2/2a/2b=>PUCCH format 3=>PUSCH in accordance with the
number of CSI CCs.
Method 2: Limitation of the Number A11 CSI Bits which are
Simultaneously Transmitted
For example, the number of minimum CSI bits, which may be
transmitted using PUSCH or PUCCHF3, may be limited to K. In this
case, if the number of all the CSI bits of which transmission is
required through the CSI report subframe is O.sub.CSI, the
following operation may be defined. For example, K may be, but not
limited to, 12 (K=12).
i) In case of O.sub.CSI.gtoreq.K (CSI initially transmitted under
the corresponding condition will be referred to as "CSI 2-1")
simultaneous transmission of the corresponding O.sub.CSI CSI bits
by using PUSCH or PUCCHF3.
ii) In case of O.sub.CSI<K (CSI initially transmitted under the
corresponding condition will be referred to as "CSI 2-2") X number
of CSIs (for CC) having the highest priority on the basis of Step 1
or 2 and a total of CSI bits of maximum integer less than 11 are
only transmitted using PUCCH formats 2/2a/2b, or all the CSIs are
dropped (in this case, separate PUCCH format 2/2a/2b allocation may
not be required).
For another example, the number of maximum CSIs (CCs), which may be
transmitted using PUSCH or PUCCHF3, may be limited to H. In this
case, the following operation may be defined in accordance with
O.sub.CSI.
i) In case of O.sub.CSI.ltoreq.H simultaneous transmission of the
corresponding O.sub.CSI CSIs (for CCs) by using PUSCH or
PUCCHF3.
ii) In case of O.sub.CSI>H transmission of Y number of CSIs (for
CCs) having the highest priority on the basis of Step 1 or 2 and a
total of CSI bits of maximum integer less than H by using PUSCH or
PUCCHF3
For another example, the number of minimum and maximum CSIs, which
may be transmitted using PUSCH or PUCCHF3 by combination of the
above two methods, may be limited to K and H, respectively. In this
case, the following operation may be defined.
i) In case of O.sub.CSI>L transmission of Y number of CSIs (for
CCs) having the highest priority on the basis of Step 1 or 2 and a
total of CSI bits of maximum integer less than H by using PUSCH or
PUCCHF3
ii) In case of H.gtoreq.O.sub.CSI.gtoreq.K simultaneous
transmission of the corresponding O.sub.CSI CSI bits by using PUSCH
or PUCCHF3
iii) O.sub.CSI<K X number of CSIs (for CC) having the highest
priority on the basis of Step 1 or 2 and a total of CSI bits of
maximum integer less than 11 are only transmitted using PUCCH
formats 2/2a/2b, or all the CSIs are dropped (in this case,
separate PUCCH format 2/2a/2b allocation may not be required).
In this case, the parameters K and H may be set UE-commonly or
UE-specifically through broadcast or L1/L2/RRC signaling.
The aforementioned description illustrates that CSI transmission is
performed using two types of physical channels. Similarly, the CSI
transmission channels may be determined in the order of PUCCH
formats 2/2a/2b=>PUCCH format 3=>PUSCH in accordance with the
number of CSI bits.
Method 3: Feedback of a Plurality of CSIs (CCs) Having the Highest
CSI Type Priority in Step 2
In Step 2, one CSI (CC), which will be a target for final
transmission, among a plurality of CSIs (CCs) having the highest
CSI type priority, is simply determined on the basis of the lowest
cell index (lowest ServCellIndex) only. Accordingly, it is likely
that CSI loss may be increased for CC having relatively high
ServCellIndex in spite of the high CSI type priority. In this
respect, in the same manner as the condition of Step 2, this method
suggests that a plurality of CSIs (for a plurality of CCs) are
transmitted using PUSCH or PUCCHF3 at the same time if the
plurality of CSIs (CCs) have the highest CSI type priority for the
CSI report subframe. If only one CSI (CC) has the highest CSI type
priority for the CSI report subframe, the corresponding CSI (for
CC) may only be transmitted using PUCCH formats 2/2a/2b.
Also, this method may be applied to a specific CSI type priority
only. For example, if a plurality of CSIs (CCs) correspond to the
first CSI types for the CSI report subframe, the corresponding CSIs
(for CCs) are transmitted using PUSCH or PUCCHF3 at the same time.
If not so, only one CSI (for CC) determined on the basis of Step
1/2 may be transmitted using the PUCCH formats 2/2a/2b. For another
example, if a plurality of CSIs (CCs) correspond to the first CSI
type for the CSI report subframe or if a plurality of CSIs (CCs)
correspond to the second CSI type and have the highest priority,
the corresponding CSIs (for CCs) may be transmitted using the PUSCH
or PUCCHF3 at the same time. If not so, only one CSI (for CC)
determined on the basis of Step 1/2 may be transmitted using the
PUCCH formats 2/2a/2b.
Method 4: Configuration of UL Channel/Format for CSI Report per
CC
This method suggests that UL channel/format used for CSI report for
each CC is configured independently per CC. In more detail, whether
CSI for corresponding CC will be transmitted using PUSCH or PUCCHF3
or PUCCH formats 2/2a/2b may be configured independently for each
CC through RRC signaling. Through this configuration, CC group,
which will be a target for CSI transmission based on PUSCH or
PUCCHF3, will be referred to as "CSI group #1". Similarly, CC
group, which will be a target for CSI transmission based on the
PUCCH formats 2/2a/2b, will be referred to as "CSI group #2". In
more detail, the base station may configure a proper CSI report
channel/format per CC (group) by considering similarity of CSI
feedback modes between CCs aggregated by the user equipment,
similarity of CSI transmission period timing (for example, period,
offset), priority for CSI protection between CCs. As the proper CSI
report channel/format is configured per CC (group), channel
information lack and scheduling restrictions, which are caused by
frequent or unnecessary (or critical) CSI drop, may be reduced.
Also, in view of efficiency in use of resources, wasteful use (for
example, large sized PUSCH or PUCCHF3 is used unnecessarily even in
case that CSI transmission for one CC is required) of PUSCH or
PUCCHF3, which requires relatively much resource consumption, may
be reduced.
Under the circumstances, if CSI transmission for one or more CCs
belonging to CSI group #1 is required for a specific subframe, CSI
for all the corresponding CCs may be transmitted through the PUSCH
or PUCCHF3. Also, if CSI transmission for one or more CCs belonging
to CSI group #2 is required for a specific subframe, CSI for one
CC, which is determined on the basis of Step 1/2 among the
corresponding CCs, may only be transmitted through the PUCCH
formats 2/2a/2b. Meanwhile, if CSI transmission for one or more CCs
belonging to CSI group #1 and CSI transmission for one or more CCs
belonging to CSI group #2 are simultaneously required for a
specific subframe, the following operations may be considered as
the case may be.
Alt 1) CSI for all of the corresponding CC(s) belonging to CSI
group #1 and the corresponding CC(s) belonging to CSI group #2 is
transmitted using PUSCH or PUCCHF3.1
Alt 2) CSI for all of the corresponding CC(s) belonging to CSI
group #1 and CSI for one CC determined by Step 1/2 based on the
corresponding CC(s) belonging to CSI group #2 are transmitted using
PUSCH or PUCCHF3.
Alt 3) CSI for the CSI group #2 is dropped, and CSI for the CSI
group #1 is transmitted using PUSCH or PUCCHF3.
Alt 4) CSI for the CSI group #1 is dropped, and CSI for one CC
determined on the basis of Step 1/2 for the CSI group #2 is only
transmitted using the PUCCH formats 2/2a/2b.
Alt 4) CSI for one CC determined on the basis of Step 1/2 for all
of the CSI group #1 and the CSI group #2 is only transmitted using
the PUCCH formats 2/2a/2b.
Alt 1 may reduce possible CSI drop and thus may be useful in view
of the aspect that channel information lack and scheduling
restrictions may be reduced. Alt 2 or 3 reduces CSI drop and at the
same time reduces a sudden increase of a code rate of PUSCH or
PUCCHF3, whereby Alt 2 or 3 may be useful in view of CSI
transmission performance. Alt 4 or 5 may maintain CSI protection
priority and at the same time reduce use frequency of PUSCH or
PUCCHF3 if possible, whereby Alt 4 or 5 may be useful in view of
efficiency in use of resources. Meanwhile, a plurality of Alt
methods may be defined, and whether any one of these methods will
be applied may be configured through RRC signaling.
Method 5: Simultaneous Transmission Method According to the
Presence of UL Data
It is considered that PUSCH is used for transmission of a plurality
of CSIs. In this case, the PUSCH means a channel which is
previously allocated for transmission of a plurality of CSIs, and
is identified from PUSCH allocated by the existing UL grant PDCCH.
For convenience, the PUSCH allocated for transmission of a
plurality of CSIs will be referred to as PUSCH_CSI, and the PUSCH
allocated by the UL grant PDCCH will be referred to as PUSCH_UG. If
there is no PUSCH_UG transmission for the CSI report subframe
except for PUSCH_CSI and UL data to be transmitted exist, the
following operation may be considered to reduce delay of UL data
transmission.
i) In case of CSI 1-1 or CSI 2-1 (that is, if the number/amount of
CSIs is more than the number/amount of minimum CSIs for
simultaneous transmission), the corresponding CSI is only
transmitted through PUSCH_CSI regardless of the presence of UL data
(if UL data exist, transmission of the corresponding UL data is
delayed).
ii) In case of CSI 1-2 or CSI 2-2 (that is, if the number/amount of
CSIs is smaller than the number/amount of minimum CSIs for
simultaneous transmission), and if UL data do not exist, the
corresponding CSI is only transmitted through PUCCH formats
2/2a/2b, or all of the CSIs are dropped (in this case, separate
PUCCH format 2/2a/2b allocation may not be required).
iii) In case of CSI 1-2 or CSI 2-2, and if UL data exist, the
corresponding CSI and UL data are transmitted through PUSCH_CSI at
the same time.
Method 6: Simultaneous Transmission Method According to the
Presence of ACK/NACK
It is considered that PUSCH is used for transmission of a plurality
of CSIs. In this case, the PUSCH means a channel which is
previously allocated for transmission of a plurality of CSIs, and
is identified from PUSCH allocated by the existing UL grant PDCCH.
For convenience, the PUSCH allocated for transmission of a
plurality of CSIs will be referred to as PUSCH_CSI, and the PUSCH
allocated by the UL grant PDCCH will be referred to as PUSCH_UG.
According to the related art, if the CSI transmission timing is the
same as the ACK/NACK transmission timing and there is no PUSCH
allocated for the corresponding subframe, CSI is dropped in
accordance with UCI priority. In this method, if there is no
PUSCH_UG transmission for the CSI report subframe except for
PUSCH_CSI and ACK/NACK for DL data exists, the following operation
may be considered to reduce loss caused by CSI drop.
i) In case of CSI 1-1 or CSI 2-1 (that is, if the number/amount of
CSIs is more than the number/amount of minimum CSIs for
simultaneous transmission), and if ACK/NACK does not exist, the
corresponding CSI is only transmitted through PUSCH_CSI.
ii) In case of CSI 1-1 or CSI 2-1, and if ACK/NACK exists (that is,
if the number/amount of CSIs is more than the number/amount of
minimum CSIs for simultaneous transmission and ACK/NACK exists),
the corresponding CSI and ACK/NACK are transmitted through
PUSCH_CSI at the same time.
iii) In case of CSI 1-2 or CSI 2-2 (that is, if the number/amount
of CSIs is smaller than the number/amount of minimum CSIs for
simultaneous transmission), and if ACK/NACK does not exist, the
corresponding CSI is only transmitted through PUCCH formats
2/2a/2b, or all of the CSIs are dropped (in this case, separate
PUCCH format 2/2a/2b allocation may not be required).
iv) In case of CSI 1-2 or CSI 2-2, and if ACK/NACK exists, the
corresponding CSI and ACK/NACK are transmitted through PUSCH_CSI at
the same time (at this time, if ACK/NACK for DL data transmitted
through PCC exists only, the CSI and the ACK/NACK may be
transmitted using the PUCCH formats 2/2a/2b, or CSI may be dropped
andACK/NACK may only be transmitted using the PUCCH formats 1a/1b
(in this case, separate PUCCH format 2/2a/2b allocation may not be
required).
Method 7: Simultaneous Transmission Method According to SR Report
Subframe
It is considered that PUSCH is used for transmission of a plurality
of CSIs. In this case, the PUSCH means a channel which is
previously allocated for transmission of a plurality of CSIs, and
is identified from PUSCH allocated by the existing UL grant PDCCH.
For convenience, the PUSCH allocated for transmission of a
plurality of CSIs will be referred to as PUSCH_CSI, and the PUSCH
allocated by the UL grant PDCCH will be referred to as PUSCH_UG.
According to the related art, if the CSI report subframe is
overlapped with the SR report subframe, CSI is dropped in
accordance with UCI priority. In this method, if the CSI report
subframe is overlapped with the SR subframe and there is no
PUSCH_UG transmission for the corresponding time except for
PUSCH_CSI, the following operation may be considered to reduce loss
caused by CSI drop.
i) In case of CSI 1-1 or CSI 2-1 (that is, if the number/amount of
CSIs is more than the number/amount of minimum CSIs for
simultaneous transmission), the corresponding CSI and 1-bit SR
(negative/positive SR) are transmitted through PUSCH_CSI at the
same time.
ii) In case of CSI 1-2 or CSI 2-2 (that is, if the number/amount of
CSIs is smaller than the number/amount of minimum CSIs for
simultaneous transmission), the corresponding CSI and 1-bit SR are
transmitted through PUCCH formats 2/2a/2b at the same time, or CSI
is dropped and 1-bit SR is only transmitted using PUCCH format 1
(in this case, separate PUCCH format 2/2a/2b allocation may not be
required).
FIG. 17 is a diagram illustrating a procedure of CSI report
according to the embodiment of the present invention when a
plurality of carriers or cells are aggregated.
Referring to FIG. 17, a plurality of CCs (or cells) are configured
for a user equipment (S1702), and a periodic CSI report mode is
configured independently for each CC (for example, in accordance
with transmission mode) (S1704). If CSI report subframes are not
overlapped with one another at the plurality of CCs (that is, if
CSI transmission for one CC is only required for the corresponding
subframe) (S1706), the CSI for the corresponding CC is transmitted
through the corresponding subframe (S1708). On the other hand, if
the CSI report subframes are overlapped with one another at the
plurality of CCs (S1706), the user equipment may determine whether
the CSI report status satisfies a predetermined condition (S1708).
In this case, if the first condition is satisfied, the user
equipment may report N (>1) number of CSIs for the plurality of
CCs (or cells) by using the first channel/format (S1712), and if
the second condition is satisfied, the user equipment may report
CSI for one CC (or cell) by using the second channel/format or drop
CSI for all of the CCs (or cells) (S1714). In this case, the first
condition and the second condition are exemplary, and three or more
conditions may be used. Also, the first channel/format may
correspond to channel/format X, and the second channel/format may
include the PUCCH formats 2/2a/2b.
For convenience, the description of the steps S1712 and S1714
corresponds to the first example of the method 1. This is
exemplary, and each condition used in step S1710 and CSI report
based on each condition may be varied depending on the description
suggested in the methods 1 to 7.
FIG. 18 is a diagram illustrating a base station and a user so
equipment, which can be applied to one embodiment of the present
invention.
Referring to FIG. 18, the wireless communication system includes a
base station (BS) 110 and a user equipment (UE) 120. The base
station 110 includes a processor 112, a memory 114, and a radio
frequency (RF) unit 116. The processor 112 may be configured to
implement procedures and/or methods suggested in the present
invention. The memory 114 is connected with the processor 112 and
stores various kinds of information related to the operation of the
processor 112. The RF unit 116 is connected with the processor 112
and transmits and/or receives a radio signal. The user equipment
120 includes a processor 122, a memory 124, and a radio frequency
(RF) unit 126. The processor 122 may be configured to implement
procedures and/or methods suggested in the present invention. The
memory 124 is connected with the processor 122 and stores various
kinds of information related to the operation of the processor 122.
The RF unit 126 is connected with the processor 122 and transmits
and/or receives a radio signal. The base station 110 and/or the
user equipment 120 may have a single antenna or multiple
antennas.
The aforementioned embodiments are achieved by combination of
structural elements and features of the present invention in a
predetermined type. Each of the structural elements or features
should be considered selectively unless specified separately. Each
of the structural elements or features may be carried out without
being combined with other structural elements or features. Also,
some structural elements and/or features may be combined with one
another to constitute the embodiments of the present invention. The
order of operations described in the embodiments of the present
invention may be changed. Some structural elements or features of
one embodiment may be included in another embodiment, or may be
replaced with corresponding structural elements or features of
another embodiment. Moreover, it will be apparent that some claims
referring to specific claims may be combined with another claims
referring to the other claims other than the specific claims to
constitute the embodiment or add new claims by means of amendment
after the application is filed.
The embodiments of the present invention have been described based
on the data transmission and reception between the base station and
the user equipment. A specific operation which has been described
as being performed by the base station may be performed by an upper
node of the base station as the case may be. In other words, it
will be apparent that various operations performed for
communication with the user equipment in the network which includes
a plurality of network nodes along with the base station may be
performed by the base station or network nodes other than the base
station. The base station may be replaced with terms such as a
fixed station, Node B, eNode B (eNB), and access point. Also, the
user equipment may be replaced with terms such as mobile station
(MS) and mobile subscriber station (MSS).
The embodiments according to the present invention may be
implemented by various means, for example, hardware, firmware,
software, or their combination. If the embodiment according to the
present invention is implemented by hardware, the embodiment of the
present invention may be implemented by one or more application
specific integrated circuits (ASICs), digital signal processors
(DSPs), digital signal processing devices (DSPDs), programmable
logic devices (PLDs), field programmable gate arrays (FPGAs),
processors, controllers, microcontrollers, microprocessors,
etc.
If the embodiment according to the present invention is implemented
by firmware or software, the embodiment of the present invention
may be implemented by a type of a module, a procedure, or a
function, which performs functions or operations described as
above. A software code may be stored in a memory unit and then may
be driven by a processor. The memory unit may be located inside or
outside the processor to transmit and receive data to and from the
processor through various means which are well known.
It will be apparent to those skilled in the art that the present
invention may be embodied in other specific forms without departing
from the spirit and essential characteristics of the invention.
Thus, the above embodiments are to be considered in all respects as
illustrative and not restrictive. The scope of the invention should
be determined by reasonable interpretation of the appended claims
and all change which comes within the equivalent scope of the
invention are included in the scope of the invention.
Industrial Applicability
The present invention may be used for a wireless communication
device such as a user equipment, a relay and a base station.
* * * * *