U.S. patent application number 14/124640 was filed with the patent office on 2014-04-24 for method and device for information transmission in wireless communication system.
This patent application is currently assigned to LG ELECTRONICS INC.. The applicant listed for this patent is Seunghee Han, Jinmin Kim, Hyunwoo Lee. Invention is credited to Seunghee Han, Jinmin Kim, Hyunwoo Lee.
Application Number | 20140112280 14/124640 |
Document ID | / |
Family ID | 47296562 |
Filed Date | 2014-04-24 |
United States Patent
Application |
20140112280 |
Kind Code |
A1 |
Lee; Hyunwoo ; et
al. |
April 24, 2014 |
METHOD AND DEVICE FOR INFORMATION TRANSMISSION IN WIRELESS
COMMUNICATION SYSTEM
Abstract
The present invention relates to a wireless communication system
and more specifically relates to a method and device for
transmitting information. A wireless communication system can
support carrier aggregation (CA). In one aspect of the present
invention, a method, in which a terminal receives information from
a base station in a wireless communication, comprises the steps of:
receiving, from the base station, first information on the
transmission method of a first channel; receiving the receiving the
first channel, from the base station, via at least one serving cell
formed in the terminal; and carrying out decoding on the first
channel in accordance with the first information. Therein, the
first channel is an enhanced physical downlink control channel
(ePDCCH), and the terminal is capable of not carrying out decoding
on the first channel in a frequency region in a present
subframe.
Inventors: |
Lee; Hyunwoo; (Gyeonggi-do,
KR) ; Han; Seunghee; (Gyeonggi-do, KR) ; Kim;
Jinmin; (Gyeonggi-do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lee; Hyunwoo
Han; Seunghee
Kim; Jinmin |
Gyeonggi-do
Gyeonggi-do
Gyeonggi-do |
|
KR
KR
KR |
|
|
Assignee: |
LG ELECTRONICS INC.
Seoul
KR
|
Family ID: |
47296562 |
Appl. No.: |
14/124640 |
Filed: |
May 31, 2012 |
PCT Filed: |
May 31, 2012 |
PCT NO: |
PCT/KR2012/004305 |
371 Date: |
December 6, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61494422 |
Jun 8, 2011 |
|
|
|
Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04L 5/001 20130101;
H04L 1/0026 20130101; H04L 1/1812 20130101; H04L 27/2636 20130101;
H04W 72/04 20130101; H04W 72/042 20130101; H04L 5/0053 20130101;
H04L 5/0094 20130101; H04W 72/044 20130101 |
Class at
Publication: |
370/329 |
International
Class: |
H04W 72/04 20060101
H04W072/04 |
Claims
1. A method for a user equipment (UE) to receive information from a
base station (BS) in a wireless communication system, the method
comprising: receiving, from the BS, first information on a
transmission method of a first channel; and decoding the first
channel in accordance with the first information, wherein the first
channel is received by the UE from the BS via at least one serving
cell configured to the UE, wherein the first channel is an enhanced
physical downlink control channel (ePDCCH), wherein the first
information includes information on a resource region in which the
first channel is received, and wherein the information on the
resource region includes at least one of time region information
and frequency region information.
2. The method according to claim 1, wherein the preset subframe is
a subframe configured as an Almost Blank Subframe (ABS).
3. The method according to claim 1, wherein the preset subframe is
a subframe set C.sub.CSI,0 or C.sub.CSI,1 configured for channel
state information (CSI) measurement.
4. The method according to claim 1, wherein the preset subframe is
a subframe configured for paging.
5. (canceled)
6. The method according to claim 1, wherein the time region
information corresponds to one of information on a symbol basis,
information on a slot basis or information on a subframe, and
wherein the frequency region information corresponds to information
on a physical resource block (PRB) basis.
7. The method according to claim 6, wherein the first information
includes at least one of information on indices of PRBs used for
the first channel from among all PRBs, information on the lowest
PRB index used for the first channel from among all PRBs, or
information indicating the indices of PRBs used for the first
channel through a bitmap of all PRBs.
8. The method according to claim 1, wherein the first information
is received from the BS through radio resource control (RRC)
signaling.
9. A user equipment (UE) for receiving information from a base
station (BS) in a wireless communication system, comprising: a
reception module for receiving, from the BS, first information on a
transmission method of a first channel; and a processor for
decoding the first channel in accordance with the first
information, wherein the first channel is received by the UE from
the BS via at least one serving cell configured to the UE, wherein
the first channel is an enhanced physical downlink control channel
(ePDCCH), wherein the first information includes information on a
resource region in which the first channel is received, and wherein
the information on the resource region includes at least one of
time region information and frequency region information.
10-16. (canceled)
17. The method according to claim 1, wherein a start orthogonal
frequency division multiplexing (OFDM) symbol position of the first
channel is determined based on ePDCCH start OFDM symbol information
included in the first information.
18. The method according to claim 1, wherein a start orthogonal
frequency division multiplexing (OFDM) symbol position of the first
channel is determined based on a number of OFDM symbols for a PDCCH
which is indicated by Physical Control Format Indicator Channel
(PCFICH).
19. The method according to claim 1, wherein the UE is configured
not to decode the first channel on a resource region overlapped
with one of a Physical Broadcast Channel (PBCH), a Primary
Synchronization Signal or a Secondary Synchronization Signal.
20. The method according to claim 1, wherein the UE does not
perform decoding the first channel in a frequency region in a
preset subframe.
Description
TECHNICAL FIELD
[0001] The present invention relates to a wireless communication
system, and more particularly, to a method and device for
transmitting information. The wireless communication system
supports carrier aggregation (CA).
BACKGROUND ART
[0002] Wireless communication systems have been widely deployed to
provide various types of communication services including voice and
data services. In general, a wireless communication system is a
multiple access system that supports communication among multiple
users by sharing available system resources (e.g. bandwidth,
transmit power, etc.) among the multiple users. The multiple access
system may adopt a multiple access scheme such as code division
multiple access (CDMA), frequency division multiple access (FDMA),
time division multiple access (TDMA), orthogonal frequency division
multiple access (OFDMA), or single carrier frequency division
multiple access (SC-FDMA).
DISCLOSURE
Technical Problem
[0003] An object of the present invention devised to solve the
problem lies in a method for efficiently transmitting information
in a wireless communication system and a device for the same.
Another object of the present invention is to provide a channel
format and signal processing scheme for efficiently transmitting
information and a device for the same. A further object of the
present invention is to provide a method for efficiently allocating
resources for transmitting information and a device for the
same.
[0004] The technical problems solved by the present invention are
not limited to the above technical problems and those skilled in
the art may understand other technical problems from the following
description.
Technical Solution
[0005] The object of the present invention can be achieved by
providing a method for a user equipment (UE) to receive information
from a base station (BS) in a wireless communication system, the
method including: receiving, from the BS, first information on a
transmission method of a first channel; receiving the first channel
from the BS via at least one serving cell configured to the UE; and
decoding the first channel in accordance with the first
information, wherein the first channel is an enhanced physical
downlink control channel (ePDCCH), and wherein the UE does not
perform decoding the first channel in a frequency region in a
preset subframe.
[0006] In another aspect of the present invention, provided herein
is a UE for receiving information from a BS in a wireless
communication system, including: a reception module for receiving,
from the BS, first information on a transmission method of a first
channel and receiving the first channel from the BS via at least
one serving cell configured to the UE; and a processor for decoding
the first channel in accordance with the first information, wherein
the first channel is an ePDCCH, and wherein the processor does not
perform decoding the first channel in a frequency region in a
preset subframe.
Advantageous Effects
[0007] According to the present invention, it is possible to
efficiently transmit information in a wireless communication
system. In addition, it is possible to provide a channel format and
signal processing scheme for efficiently transmitting information.
Furthermore, it is possible to efficiently allocate resources for
transmitting information and a device for the same. The effects of
the present invention are not limited to the above-described
effects and other effects which are not described herein will
become apparent to those skilled in the art from the following
description.
DESCRIPTION OF DRAWINGS
[0008] The accompanying drawings, which are included to provide a
further understanding of the invention, illustrate embodiments of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
[0009] FIG. 1 illustrates configurations of user equipment (UE) and
a base station (BS) to which the present invention is
applicable;
[0010] FIG. 2 illustrates a signal processing procedure through
which a UE transmits an uplink signal;
[0011] FIG. 3 illustrates a signal processing procedure through
which a BS transmits a downlink signal;
[0012] FIG. 4 illustrates SC-FDMA and OFDMA to which the present
invention is applicable;
[0013] FIG. 5 illustrates examples of mapping input symbols to
subcarriers in the frequency domain while satisfying single carrier
property;
[0014] FIG. 6 illustrates a signal processing procedure of mapping
DFT process output samples to a single carrier in clustered
SC-FDMA;
[0015] FIGS. 7 and 8 illustrate a signal processing procedure of
mapping DFT process output samples to multiple carriers in
clustered SC-FDMA;
[0016] FIG. 9 illustrates a signal processing procedure in
segmented SC-FDMA;
[0017] FIG. 10 illustrates exemplary radio frame structures used in
a wireless communication system;
[0018] FIG. 11 illustrates an uplink subframe structure;
[0019] FIG. 12 illustrates determination of a PUCCH for ACK/NACK
transmission;
[0020] FIGS. 13 and 14 illustrate slot level structures of PUCCH
formats 1a and 1b for ACK/NACK transmission;
[0021] FIG. 15 illustrates PUCCH format 2/2a/2b in the case of
normal cyclic prefix;
[0022] FIG. 16 illustrates PUCCH format 2/2a/2b in the case of
extended cyclic prefix;
[0023] FIG. 17 illustrates ACK/NACK channelization for PUCCH
formats 1a and 1b;
[0024] FIG. 18 illustrates channelization for a hybrid structure of
PUCCH format 1/1a/1b and PUCCH format 2/2a/2b in the same PRB;
[0025] FIG. 19 illustrates allocation of physical resource blocks
(PRBs);
[0026] FIG. 20 illustrates a concept of management of downlink
component carriers (DL CCs) in a BS;
[0027] FIG. 21 illustrates a concept of management of uplink
component carriers (UL CCs) in a UE;
[0028] FIG. 22 illustrates a concept of management of multiple
carriers by one MAC layer in a BS;
[0029] FIG. 23 illustrates a concept of management of multiple
carriers by one MAC layer in a UE;
[0030] FIG. 24 illustrates a concept of management of multiple
carriers by multiple MAC layers in a BS;
[0031] FIG. 25 illustrates a concept of management of multiple
carriers by multiple MAC layers in a UE;
[0032] FIG. 26 illustrates a concept of management of multiple
carriers by multiple MAC layers in a BS;
[0033] FIG. 27 illustrates a concept of management of multiple
carriers by multiple MAC layers in a UE;
[0034] FIG. 28 illustrates asymmetrical carrier aggregation in
which five DL CCs are linked to one UL CC;
[0035] FIGS. 29 to 32 illustrate PUCCH format 3 and a signal
processing procedure for the same according to an embodiment of the
present invention;
[0036] FIG. 33 illustrates ACK/NACK information transmission
structures using channel selection to which the present invention
is applied;
[0037] FIG. 34 illustrates ACK/NACK information transmission
structures using enhanced channel selection to which the present
invention is applied;
[0038] FIG. 35 illustrates an example of ACK/NACK feedback in TDD
with respect to the present invention;
[0039] FIG. 36 illustrates cross-carrier scheduling with respect to
the present invention;
[0040] FIG. 37 illustrates a PDSCH or PDCCH in a subframe n-k
corresponding to PUCCH transmission in a subframe n for DCI format
1/1A/1B/1D/2/2A/2B/2C;
[0041] FIG. 38 illustrates a PDCCH subframe n-k' transmitting DCI
format 0/4 for allocating a PUSCH in a subframe n;
[0042] FIG. 39 illustrates a subframe n+k to which a PUSCH is
allocated when DCI format 0/4 or a PHICH for normal HARQ operation
is transmitted in a subframe n;
[0043] FIG. 40 illustrates an example of transmission of a PUSCH in
a subframe n+k when a PHICH corresponding to the PUSCH is
transmitted in a subframe n-1 using subframe bundling in TDD UL/DL
configuration #0 and an example of transmission of a PUSCH in
subframe n+k when DCI format 0/4 is transmitted in subframe n using
subframe bundling;
[0044] FIG. 41 illustrates an example of transmission of a PUSCH in
a subframe n+k when a PHICH corresponding to the PUSCH is
transmitted in a subframe n-1 using subframe bundling in TDD UL/DL
configurations #1 to #6 and an example of transmission of a PUSCH
in the subframe n+k when DCI format 0/4 is transmitted in the
subframe n using subframe bundling;
[0045] FIG. 42 illustrates an example of transmission of a HARQ-ACK
response to a PUSCH in a subframe n through a PHICH in a subframe
n+k.sub.PHICH;
[0046] FIG. 43 illustrates an example in which a HARQ-ACK response
received through a PHICH in a subframe i corresponds to a PUSCH in
a subframe i-k;
[0047] FIG. 44 illustrates interference generated in a mobile
network, which is different from interference generated in a
homogeneous network with respect to the present invention;
[0048] FIG. 45 illustrates an exemplary ABS configuration of a
macro cell in macro-pico scenarios according to the present
invention;
[0049] FIG. 46 illustrates an exemplary CSG scenario according to
the present invention;
[0050] FIG. 47 illustrates an exemplary pico scenario according to
the present invention;
[0051] FIG. 48 illustrates a method for mitigating interference by
allocating PDSCHs in orthogonal frequency regions to UEs located at
a cell edge, which is used when BSs exchange scheduling information
according to the present invention;
[0052] FIG. 49 illustrates influence of interference in different
UL/DL configurations with respect to the present invention;
[0053] FIG. 50 illustrates an ePDCCH in the time domain according
to the present invention;
[0054] FIG. 51 illustrates a configuration of an ePDCCH occupying a
subframe according to the present invention;
[0055] FIG. 52 illustrates a configuration of a TDM ePDCCH
occupying a subframe according to the present invention;
[0056] FIG. 53 illustrates a configuration of an ePDCCH occupying a
first slot according to the present invention;
[0057] FIG. 54 illustrates a configuration of a TDM ePDCCH
occupying a first slot according to the present invention;
[0058] FIG. 55 illustrates temporal positions of a PSS, SSS and
PBCH in frame structure type 1 according to the present
invention;
[0059] FIG. 56 illustrates temporal positions of a PSS, SSS and
PBCH in frame structure type 1 according to the present invention;
and
[0060] FIG. 57 illustrates temporal positions of a PSS, SSS and
PBCH in frame structure type 2 according to the present
invention.
BEST MODE
[0061] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. The detailed description,
which will be given below with reference to the accompanying
drawings, is intended to explain exemplary embodiments of the
present invention, rather than to show the only embodiments that
can be implemented according to the present invention. The
following detailed description includes specific details in order
to provide a thorough understanding of the present invention.
However, it will be apparent to those skilled in the art that the
present invention may be practiced without such specific
details.
[0062] Techniques described herein can be used in various wireless
access systems such as Code Division Multiple Access (CDMA),
Frequency Division Multiple Access (FDMA), Time Division Multiple
Access (TDMA), Orthogonal Frequency Division Multiple Access
(OFDMA), Single Carrier-Frequency Division Multiple Access
(SC-FDMA), etc. CDMA may be implemented as a radio technology such
as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may
be implemented as a radio technology such as Global System for
Mobile communications (GSM)/General Packet Radio Service
(GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be
implemented as a radio technology such as IEEE 802.11 (Wi-Fi), IEEE
802.16 (WiMAX), IEEE 802.20, Evolved-UTRA (E-UTRA) etc. UTRA is a
part of Universal Mobile Telecommunication System (UMTS). 3GPP LTE
is a part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs
OFDMA for downlink and SC-FDMA for uplink. LTE-A is evolved from
3GPP LTE. For clarity, the following description focuses on 3GPP
LTE/LTE-A. However, technical features of the present invention are
not limited thereto. For example, even if the following description
is made based on a wireless communication system corresponding to
3GPP LTE/LTT-A, the present invention is applicable to other
wireless communication systems except for specific features of 3GPP
LTE/LTE-A.
[0063] In some instances, well-known structures and devices are
omitted in order to avoid obscuring the concepts of the present
invention and the important functions of the structures and devices
are shown in block diagram form. The same reference numbers will be
used throughout the drawings to refer to the same or like
parts.
[0064] In the present invention a terminal refers to a device that
can be fixed or mobile and communicates with a base station to
transmit/receive various types of data and control information. The
term "terminal" may be used interchangeably with terms "user
equipment (UE)", "mobile station (MS)", "mobile terminal (MT)",
"user terminal (UT)", "subscriber station (SS)", "wireless device",
"personal digital assistant (PDA)", "wireless modem", "handheld
device", etc.
[0065] A base station refers to a fixed station communicating with
UEs or other base stations and communicates with UEs and other base
stations to exchange various types of data and information with the
same. The base station may be referred to as evolved-nodeB (eNB),
base transceiver system (BTS), access point (AP), etc.
[0066] In the present invention, allocation of a specific signal to
a frame/subframe/slot/carrier/subcarrier refers to transmission of
the specific signal through the corresponding carrier/subcarrier
for the duration or at the timing of the corresponding
frame/subframe/slot.
[0067] In the present invention, a rank or a transport rank refers
to the number of layers multiplexed or allocated to a single OFDM
symbol or a single resource element.
[0068] In the present invention, PDCCH (physical downlink control
channel)/PCFICH (physical control format indicator channel)/PHICH
(physical hybrid automatic retransmit request indicator
channel)/PDSCH (physical downlink shared channel) respectively
refer to sets of resource elements carrying DCI (downlink control
information)/CFI (control format indicator)/ACK/NACK
(acknowledgement/negative ACK)/downlink data for uplink
transmission.
[0069] In addition, PUCCH (physical uplink control channel)/PUSCH
(physical uplink shared channel)/PRACH (physical random access
channel) respectively refer to sets of resource elements carrying
UCI (uplink control information)/uplink data/random access
signal.
[0070] In particular, resource elements (REs) allocated or
belonging to PDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH are
referred to as PDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH REs or
PDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH resources.
[0071] Accordingly, transmission of PUCCH/PUSCH/PRACH by a UE
corresponds to transmission of UCI/uplink data/random access signal
on PUSCH/PUCCH/PRACH. In addition, transmission of
PDCCH/PCFICH/PHICH/PDSCH by a BS corresponds to transmission of
DCI/downlink data on PDCCH/PCFICH/PHICH/PDSCH.
[0072] Mapping of ACK/NACK information to a specific constellation
point corresponds to mapping of the ACK/NACK information to a
specific complex modulation symbol. In addition, mapping of
ACK/NACK information to a specific complex modulation symbol
corresponds to modulation of the ACK/NACK information into the
specific complex modulation symbol.
[0073] FIG. 1 illustrates configurations of a UE and a BS to which
the present invention is applicable. The UE serves as a transmitter
on uplink and operates as a receiver on downlink. The BS operates
as a receiver on uplink and functions as a transmitter on
downlink.
[0074] Referring to FIG. 1, the UE and the BS respectively include
antennas 500a and 500b for receiving information, data, signals or
messages, transmitters 100a and 100b for transmitting information,
data, signals or messages by controlling the antennas, receivers
300a and 300b for receiving information, data, signals or messages
by controlling the antennas, and memories 200a and 200b temporarily
or permanently storing information regarding the wireless
communication system. In addition, the UE and the BS respectively
include processors 400a and 400b connected to components such as
the transmitters, receivers and memories and configured to control
the components.
[0075] The transmitter 100a, the receiver 300a, the memory 200a and
processor 400a included in the UE may be implemented as independent
components by respective chips or two or more thereof may be
implemented as a single chip. The transmitter 100b, the receiver
300b, the memory 200b and processor 400b included in the BS may be
implemented as independent components by respective chips or two or
more thereof may be implemented as a single chip. The transmitter
and receiver may be integrated into a transceiver in the UE or
BS.
[0076] The antennas 500a and 500b transmit signals generated in the
transmitters 100a and 100b to the outside or receive external
signals and deliver the received signals to the receivers 300a and
300b. The antennas 500a and 500b are also called antenna ports. An
antenna port may correspond to a physical antenna or a combination
of a plurality of physical antennas. A transceiver supporting MIMO
(multiple input multiple output) for transmitting/receiving data
using multiple antennas may be connected to two or more
antennas.
[0077] The processors 400a and 400b control the overall operation
of components or modules included in the UE or BS. Particularly,
the processors 400a and 400b may execute various control functions
for performing the present invention, a MAC (medium access control)
frame variation control function according to service
characteristics and propagation environment, a power saving mode
function for controlling idle operation, a handover function,
authentication and encoding functions, etc. The processors 400a and
400b may be called controllers, microcontrollers, microprocessors
or microcomputers. The processors 400a and 400b may be implemented
by hardware, firmware, software or a combination thereof.
[0078] In hardware implementation, ASICs (application specific
integrated circuits), DSPs (digital signal processors), DSPDs
(digital signal processing devices), PLDs (programmable logic
devices), FPGAs (field programmable gate arrays), etc. configured
to implement the present invention may be included in the
processors 400a and 400b.
[0079] In a firmware or software configuration, the embodiments of
the present invention may be implemented in the form of a module, a
procedure, a function, etc. Firmware or software configured to
implement the present invention may be included in the processors
400a and 400b or stored in the memories 200a and 200b and executed
by the processors 400a and 400b.
[0080] The transmitters 100a and 100b perform predetermined coding
and modulation on a signal or data, which is scheduled by the
processors 400a and 400b or a scheduler connected to the processors
and transmitted to the outside, and transmit the modulated signal
or data to the antennas 500a and 500b. The transmitters 100a and
100b and the receivers 300a and 300b of the UE and BS may be
configured in a different manner according to a procedure of
processing a transmitted signal and a received signal.
[0081] The memories 200a and 200b may store programs for processing
and control of the processors 400a and 400b and temporarily store
input/output information. Furthermore, the memories 200a and 200b
may be used as buffers. The memories may be implemented using flash
memory, a hard disc, a multimedia card micro type or card type
memory (e.g. SD or XD memory), a random access memory (RAM), a
static RAM (SRAM), a read-only memory (ROM), an electrically
erasable programmable read-only memory (EEPROM), a programmable ROM
(PROM), a magnetic memory, a magnetic disc, an optical disc,
etc.
[0082] FIG. 2 illustrates a signal processing procedure through
which a UE transmits an uplink signal. Referring to FIG. 2, the
transmitter 100a included in the UE may include a scrambling module
201, a modulation mapper 202, a precoder 203, a resource element
mapper 204 and an SC-FDMA signal generator 205.
[0083] To transmit the uplink signal, the scrambling module 201 of
the UE may scramble the uplink signal using a scramble signal. The
scrambled signal is input to the modulation mapper 202 in which the
scrambled signal is modulated into complex symbols using binary
phase shift keying (BPSK), quadrature phase shift keying (QPSK) or
16-quadrature amplitude modulation (QAM)/64-QAM according to signal
type and/or channel status. The modulated complex symbols are
processed by the precoder 203, and then applied to the resource
element mapper 204. The resource element mapper 204 may map the
complex symbols to time-frequency resource elements. The signal
processed in this manner may be subjected to the SC-FDMA signal
generator 205 and transmitted to a BS through an antenna.
[0084] FIG. 3 illustrates a signal processing procedure through
which the BS transmits a downlink signal. Referring to FIG. 3, the
transmitter 100b included in the BS may include a scrambling module
301, a modulation mapper 302, a layer mapper 303, a precoder 304, a
resource element mapper 305 and an OFDMA signal generator 306.
[0085] To transmit a signal or one or more codewords on downlink,
the signal or codewords may be modulated into complex symbols
through the scrambling module 301 and the modulation mapper 302 as
in the uplink shown in FIG. 2. Then, the complex symbols are mapped
to a plurality of layers by the layer mapper 303. The layers may be
multiplied by a precoding matrix in the precoder 304 and allocated
to transport antennas. The processed signals for the respective
antennas may be mapped to time-frequency resource elements by the
resource element mapper 305 and subjected to the OFDM signal
generator 306 to be transmitted through the antennas.
[0086] When the UE transmits an uplink signal in a wireless
communication system, a peak-to-average ratio (PAPR) becomes a
problem, as compared to a case in which the BS transmits a downlink
signal. Accordingly, uplink signal transmission uses SC-FDMA while
downlink signal transmission uses OFDMA, as described above with
reference to FIGS. 2 and 3.
[0087] FIG. 4 illustrates SC-FDMA and OFDMA to which the present
invention is applied. 3GPP employs OFDMA on downlink and uses
SC-FDMA on uplink.
[0088] Referring to FIG. 4, both a UE for transmitting an uplink
signal and a BS for transmitting a downlink signal include a
serial-to-parallel converter 401, a subcarrier mapper 403, an
M-point IDFT module 404, and a cyclic prefix (CP) adder 406. The UE
for transmitting a signal according to SC-FDMA additionally
includes an N-point DFT module 402. The N-point DFT module 402
cancels some parts of the influence of IDFT of the M-point IDFT
module 404 such that a transmission signal has single carrier
property.
[0089] SC-FDMA needs to satisfy single carrier property. FIG. 5
illustrates examples of mapping input symbols to subcarriers in the
frequency domain, which satisfies single carrier property. When DFT
symbols are allocated to subcarriers according to one of FIGS. 5(a)
and 5(b), a transmission signal satisfying single carrier property
can be obtained. FIG. 5(a) illustrates a localized mapping scheme
and FIG. 5(b) illustrates a distributed mapping scheme.
[0090] Clustered DFT-s-OFDM may be employed by the transmitters
100a and 100b. Clustered DFT-s-OFDM, which is a modified version of
SC-FDMA, divides a signal that has passed through a precoder into
several sub-blocks and discretely maps the sub-groups to
subcarriers. FIG. 8 illustrates an example of mapping input symbols
to a single carrier according to clustered DFT-s-OFDM.
[0091] FIG. 6 illustrates a signal processing procedure for mapping
DFT process output samples to a single carrier in clustered
SC-FDMA. FIGS. 7 and 8 illustrate signal processing procedures for
mapping DFT process output samples to multiple carriers in
clustered SC-FDMA. FIG. 6 shows an example of application of
intra-carrier clustered SC-FDMA while FIGS. 7 and 8 show examples
of application of inter-carrier clustered SC-FDMA. FIG. 7
illustrates a case in which a signal is generated through a single
IFFT block when subcarrier spacing between neighboring component
carriers is set while component carriers are contiguously allocated
in the frequency domain. FIG. 8 shows a case in which a signal is
generated through a plurality of IFFT blocks when component
carriers are non-contiguously allocated in the frequency
domain.
[0092] FIG. 9 illustrates a signal processing procedure in
segmented SC-FDMA.
[0093] Segmented SC-FDMA is a simple extension of the DFT spreading
and IFFT subcarrier mapping structure of the conventional SC-FDMA,
when the number of DFT blocks is equal to the number of IFFT blocks
and thus the DFT blocks and the IFFT blocks are in one-to-one
correspondence. While the term `segmented SC-FDMA` is adopted
herein, it may also be called NxSC-FDMA or NxDFT-s-OFDMA. Referring
to FIG. 9, the segmented SC-FDMA is characterized in that total
time-domain modulation symbols are divided into N groups (N is an
integer larger than 1) and a DFT process is performed on a
group-by-group basis to relieve the single carrier property
constraint.
[0094] FIG. 10 illustrates exemplary radio frame structures used in
a wireless communication system. FIG. 10(a) illustrates a radio
frame according to frame structure type 1 (FS-1) of 3GPP LTE/LTE-A
and FIG. 10(b) illustrates a radio frame according to frame
structure type 2 (FS-2) of 3GPP LTE/LTE-A. The frame structure of
FIG. 10(a) can be applied to FDD (frequency division duplex) mode
and half FDD (H-FDD) mode. The frame structure of FIG. 10(b) can be
applied to TDD (time division duplex) mode.
[0095] Referring to FIG. 10, a radio frame is 10 ms (307200Ts) long
in 3GPP LTE/LTE-A, including 10 equally sized subframes. The 10
subframes of the radio frame may be numbered. Herein, T.sub.s is a
sampling time, expressed as T.sub.s=1/(2048.times.15 kHz). Each
subframe is 1 ms long, including two slots. The 20 slots of the
radio frame may be sequentially numbered from 0 to 19. Each slot
has a length of 0.5 ms. A time required to transmit one subframe is
defined as a transmission time interval (TTI). Time resources may
be identified by a radio frame number (or a radio frame index), a
subframe number (or a subframe index), and a slot number (or a slot
index).
[0096] Different radio frames may be configured for different
duplex modes. For example, downlink transmission is distinguished
from uplink transmission by frequency in the FDD mode. Therefore, a
radio frame includes only downlink subframes or only uplink
subframes.
[0097] On the other hand, since downlink transmission is
distinguished from uplink transmission by time in the TDD mode, the
subframes of a radio frame are divided into downlink subframes and
uplink subframes.
[0098] FIG. 11 illustrates an uplink subframe structure to which
the present invention is applied. Referring to FIG. 11, an uplink
subframe may be divided into a control region and a data region in
the frequency domain. At least one PUCCH may be allocated to the
control region to transmit uplink control information (UCI). In
addition, at least one PUSCH may be allocated to the data region to
transmit user data. If a UE adopts SC-FDMA in LTE release 8 or
release 9, it cannot transmit a PUCCH and a PUSCH simultaneously in
order to maintain the single carrier property.
[0099] UCI transmitted on a PUCCH differs in size and usage
depending on PUCCH formats. The size of UCI may also vary according
to coding rate. For example, the following PUCCH formats may be
defined.
[0100] (1) PUCCH Format 1: used for On-Off keying (OOK) modulation
and scheduling request (SR).
[0101] (2) PUCCH Formats 1a and 1b: used for transmission of
ACK/NACK information.
[0102] 1) PUCCH Format 1a: 1-bit ACK/NACK information modulated in
BPSK
[0103] 2) PUCCH Format 1b: 2-bit ACK/NACK information modulated in
QPSK
[0104] (3) PUCCH Format 2: modulated in QPSK and used for channel
quality indicator (CQI) transmission.
[0105] (4) PUCCH Formats 2a and 2b: used for simultaneous
transmission of a CQI and ACK/NACK information.
[0106] Table 1 lists modulation schemes and numbers of bits per
subframe for PUCCH formats and Table 2 lists numbers of reference
signals (RSs) per slot for PUCCH formats. Table 3 lists SC-FDMA
symbol positions of RSs for PUCCH formats. In Table 1, PUCCH
Formats 2a and 2b are for the case of a normal CP.
TABLE-US-00001 TABLE 1 PUCCH Format Modulation scheme Number of
Bits per Subframe 1 N/A N/A 1a BPSK 1 1b QPSK 2 2 QPSK 20 2a QPSK +
BPSK 21 2b QPSK + BPSK 22
TABLE-US-00002 TABLE 2 PUCCH Format Normal CP Extended CP 1, 1a, 1b
3 2 2 2 1 2a, 2b 2 N/A
TABLE-US-00003 TABLE 3 SC-FDMA Symbol Position of RS PUCCH Format
Normal CP Extended CP 1, 1a, 1b 2, 3, 4 2, 3 2, 2a, 2b 1, 5 3
[0107] Subcarriers far from a DC (Direct Current) subcarrier are
used for the control region in the uplink subframe. In other words,
subcarriers at both ends of an uplink transmission bandwidth are
allocated for transmission of UCI. The DC subcarrier is a component
that is spared from signal transmission and mapped to carrier
frequency f.sub.0 during frequency upconversion performed by an
OFDMA/SC-FDMA signal generator.
[0108] A PUCCH from one UE is allocated to an RB pair in a subframe
and the RBs of the RB pair occupy different subcarriers in two
slots. This PUCCH allocation is called frequency hopping of an RB
pair allocated to a PUCCH over a slot boundary. However, if
frequency hopping is not applied, the RB pair occupies the same
subcarriers in two slots. Since a PUCCH from a UE is allocated to
an RB pair in a subframe irrespective of frequency hopping, the
same PUCCH is transmitted twice, each time in one RB of each slot
in the subframe.
[0109] Hereinafter, an RB pair used for transmission of a PUCCH in
a subframe is referred to as a PUCCH region. A PUCCH region and a
code used therein are referred to as a PUCCH resource. That is,
different PUCCH resources may have different PUCCH regions or may
have different codes in the same PUCCH regions. For convenience, a
PUCCH carrying ACK/NACK information is referred to as an ACK/NACK
PUCCH, a PUCCH carrying CQI/PMI/RI information is referred to as a
channel state information (CSI) PUCCH, and a PUCCH carrying SR
information is referred to as an SR PUCCH.
[0110] A BS allocates PUCCH resources to a UE explicitly or
implicitly, for transmission of UCI.
[0111] UCI such as ACK/NACK information, CQI information, PMI
information, RI information, and SR information may be transmitted
in the control region of an uplink subframe.
[0112] The UE and the BS transmit and receive signals or data from
or to each other in the wireless communication system. When the BS
transmits data to the UE, the UE decodes the received data. If data
decoding is successful, the UE transmits an ACK to the BS. On the
contrary, if data decoding fails, the UE transmits a NACK to the
BS. The same applies to the opposite case, that is, the case where
the UE transmits data to the BS. In the 3GPP LTE system, the UE
receives a PDSCH from the BS and transmits an ACK/NACK for the
received PDSCH on a PUCCH that is implicitly determined by a PDCCH
carrying scheduling information for the PDSCH. A state in which the
UE does not receive data may be regarded as a discontinuous
transmission (DTX) state. In this case, the state may be processed
as a case in which there is no received data according to a
predetermined rule or a NACK case (in which decoding of data is not
successful although the data is received).
[0113] FIG. 12 illustrates a structure for determining a PUCCH for
ACK/NACK transmission, to which the present invention is
applied.
[0114] A PUCCH that will carry ACK/NACK information is not
allocated to a UE in advance. Rather, a plurality of PUCCHs is used
separately at each time instant by a plurality of UEs within a
cell. Specifically, a PUCCH that a UE will use to transmit ACK/NACK
information is implicitly determined on the basis of a PDCCH
carrying scheduling information for a PDSCH that delivers downlink
data. An entire area carrying PDCCHs in a downlink subframe
includes a plurality of control channel elements (CCEs) and a PDCCH
transmitted to a UE includes one or more CCEs. A CCE includes a
plurality of (e.g. 9) resource element groups (REGs). One REG
includes four contiguous REs except for an RS. The UE transmits
ACK/NACK information on an implicit PUCCH that is derived or
calculated by a function of a specific CCE index (e.g. the first or
lowest CCE index) from among the indexes of CCEs included in a
received PDCCH.
[0115] Referring to FIG. 12, the lowest CCE index of a PDCCH
corresponds to a PUCCH resource index for ACK/NACK transmission. As
illustrated in FIG. 12, on the assumption that a PDCCH including
CCEs #4, #5 and #6 delivers scheduling information for a PDSCH to a
UE, the UE transmits an ACK/NACK to a BS on a PUCCH, for example,
PUCCH #4 derived or calculated using the lowest CCE index of the
PDCCH, CCE index 4.
[0116] In the illustrated case of FIG. 12, there are up to M' CCEs
in a downlink subframe and up to M PUCCHs in an uplink subframe.
Although M may be equal to M', M may be different from M' and CCEs
may be mapped to PUCCHs in an overlapping manner. For instance, a
PUCCH resource index may be calculated by the following
equation.
n.sup.(1).sub.PUCCH=n.sub.CCE+N.sup.(1).sub.PUCCH [Equation 1]
[0117] Here, n.sup.(1).sub.PUCCH denotes the index of a PUCCH
resource for transmitting ACK/NACK information, N.sup.(1).sub.PUCCH
denotes a signal value received from a higher layer, and n.sub.CCE
denotes the lowest of CCE indexes used for transmission of a
PDCCH.
[0118] FIGS. 13 and 14 illustrate slot-level structures of PUCCH
Formats 1a and 1b for ACK/NACK transmission.
[0119] FIG. 13 illustrates PUCCH Formats 1a and 1b in case of a
normal CP and FIG. 14 illustrates PUCCH Formats 1a and 1b in case
of an extended CP. The same UCI is repeated on a slot basis in a
subframe in PUCCH Format 1a and 1b. A UE transmits an ACK/NACK
signal in the resources of a different cyclic shift (CS) (a
frequency-domain code) of a computer-generated constant amplitude
zero auto correlation (CG-CAZAC) sequence and an orthogonal cover
(OC) or orthogonal cover code (OCC) (a time-domain spreading code).
The OC includes, for example, a Walsh/DFT orthogonal code. Given
six CSs and three OCs, a total of 18 UEs may be multiplexed into
the same PRB, for a single antenna. An OC sequence w0, w1, w2 and
w3 is applicable to a time domain (after FFT modulation) or to a
frequency domain (before FFT modulation). PUCCH Format 1 for
transmitting SR information is the same as PUCCH Formats 1a and 1b
in terms of slot-level structure and different from PUCCH Formats
1a and 1b in terms of modulation.
[0120] PUCCH resources composed of a CS, an OC, and a physical
resource block (PRB) may be allocated to a UE by radio resource
control (RRC) signaling, for transmission of SR information and an
ACK/NACK for semi-persistent scheduling (SPS). As described before
with reference to FIG. 12, PUCCH resources may be indicated to a UE
implicitly using the lowest CCE index of a PDCCH corresponding to a
PDSCH or the lowest CCE index of a PDCCH for SPS release, for
dynamic ACK/NACK (or an ACK/NACK for non-persistent scheduling)
feedback or ACK/NACK feedback for a PDCCH indicating SPS
release.
[0121] FIG. 15 illustrates PUCCH Format 2/2a/2b in case of a normal
CP and FIG. 16 illustrates PUCCH Format 2/2a/2b in case of an
extended CP. Referring to FIGS. 15 and 16, one subframe includes 10
QPSK symbols except for an RS symbol in case of a normal CP. Each
QPSK symbol is spread with a CS in the frequency domain and then
mapped to a corresponding SC-FDMA symbol. SC-FDMA symbol-level CS
hopping may be used to randomize inter-cell interference. An RS may
be code division multiplexed (CDM) using a CS. For example, if
there are 12 or 6 available CSs, 12 or 6 UEs may be multiplexed in
the same PRB. That is, a plurality of UEs may be multiplexed using
CS+OC+PRB and CS+PRB in PUCCH Formats 1/1a/1b and 2/2a/2b.
[0122] OCs of length 4 or length 3 for PUCCH Format 1/1a/1b are
illustrated in Table 4 and Table 5 below.
TABLE-US-00004 TABLE 4 Sequence Index Orthogonal sequence 0 [+1 +1
+1 +1] 1 [+1 -1 +1 -1] 2 [+1 -1 -1 +1]
TABLE-US-00005 TABLE 5 Sequence Index Orthogonal sequence 0 [1 1 1]
1 [1 e.sup.j2.pi./3 e.sup.j4.pi./3] 2 [1 e.sup.j4.pi./3
e.sup.j2.pi./3]
[0123] OCs for RSs in PUCCH Format 1/1a/1b are given in Table 6
below.
TABLE-US-00006 TABLE 6 Sequence Index Normal CP Extended CP 0 [1 1
1] [1 1] 1 [1 e.sup.j2.pi./3 e.sup.j4.pi./3] [1 -1] 2 [1
e.sup.j4.pi./3 e.sup.j2.pi./3] N/A
[0124] FIG. 17 illustrates ACK/NACK channelization for PUCCH
Formats 1a and 1b. In FIG. 14, .DELTA..sub.shift.sup.PUCCH=2.
[0125] FIG. 18 illustrates channelization for a hybrid structure of
PUCCH Format 1/1a/1b and PUCCH Format 2/2a/2b in the same PRB.
[0126] CS hopping and OC re-mapping may be performed as
follows.
[0127] (1) Symbol-based cell-specific CS hopping to randomize
inter-cell interference
[0128] (2) Slot-level CS/OS re-mapping
[0129] 1) for randomization of inter-cell interference
[0130] 2) slot-based approach for mapping between ACK/NACK channels
and resources k
[0131] Meanwhile, resources n.sub.r for PUCCH Format 1/1a/1b
include the following combinations.
[0132] (1) CS (identical to DFT OC at symbol level) (n.sub.cs)
[0133] (2) OC (OC at slot level) (n.sub.oc)
[0134] (3) Frequency RB (n.sub.rb)
[0135] Let the indexes of a CS, an OC, and an RB be denoted by
n.sub.cs, n.sub.oc, and n.sub.rb, respectively. Then, a
representative index n.sub.r includes n.sub.cs, n.sub.oc, and
n.sub.rb. n.sub.r satisfies n.sub.r=(n.sub.cs, n.sub.oc,
n.sub.rb).
[0136] A combination of an ACK/NACK and a CQI, PMI, RI and CQI may
be delivered in PUCCH Format 2/2a/2b. Reed Muller (RM) channel
coding may be applied.
[0137] For example, channel coding for an uplink CQI is described
as follows in the LTE system. A bit stream .alpha..sub.0,
.alpha..sub.1, .alpha..sub.3, . . . , .alpha..sub.A-1 is
channel-encoded with a (20, A) RM code. Table 7 lists base
sequences for the (20, A) code. .alpha..sub.0 and .alpha..sub.A-1
are the Most Significant Bit (MS) and Least Significant Bit (LSB),
respectively. Aside from simultaneous transmission of a CQI and an
ACK/NACK, up to 11 bits can be transmitted in case of an extended
CP. A bit stream may be encoded to 20 bits by an RM code and then
modulated in QPSK. Before QPSK modulation, the coded bits may be
scrambled.
TABLE-US-00007 TABLE 7 1 M.sub.1,0 M.sub.1,1 M.sub.1,2 M.sub.1,3
M.sub.1,4 M.sub.1,5 M.sub.1,6 M.sub.1,7 M.sub.1,8 M.sub.1,9
M.sub.1,10 M.sub.1,11 M.sub.1,12 0 1 1 0 0 0 0 0 0 0 0 1 1 0 1 1 1
1 0 0 0 0 0 0 1 1 1 0 2 1 0 0 1 0 0 1 0 1 1 1 1 1 3 1 0 1 1 0 0 0 0
1 0 1 1 1 4 1 1 1 1 0 0 0 1 0 0 1 1 1 5 1 1 0 0 1 0 1 1 1 0 1 1 1 6
1 0 1 0 1 0 1 0 1 1 1 1 1 7 1 0 0 1 1 0 0 1 1 0 1 1 1 8 1 1 0 1 1 0
0 1 0 1 1 1 1 9 1 0 1 1 1 0 1 0 0 1 1 1 1 10 1 0 1 0 0 1 1 1 0 1 1
1 1 11 1 1 1 0 0 1 1 0 1 0 1 1 1 12 1 0 0 1 0 1 0 1 1 1 1 1 1 13 1
1 0 1 0 1 0 1 0 1 1 1 1 14 1 0 0 0 1 1 0 1 0 0 1 0 1 15 1 1 0 0 1 1
1 1 0 1 1 0 1 16 1 1 1 0 1 1 1 0 0 1 0 1 1 17 1 0 0 1 1 1 0 0 1 0 0
1 1 18 1 1 0 1 1 1 1 1 0 0 0 0 0 19 1 0 0 0 0 1 1 0 0 0 0 0 0
[0138] Channel-coded bits b.sub.0, b.sub.1, b.sub.2, b.sub.3, . . .
, b.sub.B-1 may be generated by Equation 2.
b i = n = 0 A - 1 ( a n M i , n ) mod 2 [ Equation 2 ]
##EQU00001##
[0139] Here, i=0, 1, 2, . . . , B-1.
[0140] Table 8 illustrates a UCI field for feedback of a broadband
report (a single antenna port, transmit diversity, or open loop
spatial multiplexing PDSCH) CQI.
TABLE-US-00008 TABLE 8 Field Bandwidth Broadband CQI 4
[0141] Table 9 illustrates a UCI field for feedback of a broadband
CQI and a PMI. This field reports transmission of a closed loop
spatial multiplexing PDSCH.
TABLE-US-00009 TABLE 9 Bandwidth 2 antenna ports 4 antenna ports
Field Rank = 1 Rank = 2 Rank = 1 Rank > 1 Wideband CQI 4 4 4 4
Spatial-domain 0 3 0 3 differential CQI PMI 2 1 4 4
[0142] Table 10 illustrates a UCI field to feedback an RI for a
broadband report.
TABLE-US-00010 TABLE 10 Bit widths 4 antenna ports Field 2 antenna
ports Up to 2 layers Up to 4 layers RI 1 1 2
[0143] FIG. 19 illustrates PRB allocation. Referring to FIG. 19, a
PRB may be used to carry a PUCCH in slot n.sub.s.
[0144] A multi-carrier system or carrier aggregation (CA) system is
a system using a plurality of carriers each having a narrower
bandwidth than a target bandwidth in order to support broadband.
When a plurality of carriers each having a narrower bandwidth than
a target band are aggregated, the bandwidth of each of the
aggregated carriers may be limited to a bandwidth used in a legacy
system in order to ensure backward compatibility with the legacy
system. For example, the legacy LTE system supports 1.4, 3, 5, 10,
15, and 20 MHz and the LTE-A system evolved from the LTE system may
support a broader bandwidth than 20 MHz using only bandwidths
supported by the LTE system. Alternatively, CA may be supported by
defining a new bandwidth irrespective of the bandwidths used in the
legacy system. The term multi-carrier is used interchangeably with
CA and spectrum aggregation. In addition, CA covers both contiguous
CA and non-contiguous CA. Furthermore, CA my cover both intra-band
CA and inter-band CA.
[0145] FIG. 20 is a conceptual view illustrating DL CC management
at a BS and FIG. 21 illustrates a conceptual view illustrating UL
CC management at a UE. For convenience, a higher layer will be
referred simply as a MAC layer in FIGS. 19 and 20.
[0146] FIG. 22 is a conceptual view illustrating multi-carrier
management of one MAC layer at a BS and FIG. 23 is a conceptual
view illustrating multi-carrier management of one MAC layer at a
UE.
[0147] Referring to FIGS. 22 and 23, one MAC layer performs
transmission and reception by managing and operating one or more
frequency carriers. Because the frequency carriers managed by the
single MAC layer do not need to be contiguous, this multi-carrier
management scheme is more flexible in terms of resource management.
In FIGS. 22 and 23, one physical (PHY) layer refers to one CC, for
convenience. Yet, a PHY layer is not necessarily an independent
radio frequency (RF) device. While one independent RF device
generally corresponds to one PHY layer, it may include a plurality
of PHY layers.
[0148] FIG. 24 is a conceptual view illustrating multi-carrier
management of a plurality of MAC layers at a BS, FIG. 25 is a
conceptual view illustrating multi-carrier management of a
plurality of MAC layers at a UE, FIG. 26 is another conceptual view
illustrating multi-carrier management of a plurality of MAC layers
at a BS, and FIG. 27 is another conceptual view illustrating
multi-carrier management of a plurality of MAC layers at a UE.
[0149] Apart from the structures illustrated in FIGS. 22 and 23, a
plurality of MAC layers may control a plurality of carriers, as
illustrated in FIGS. 24 to 27.
[0150] Each MAC layer may control one carrier in a one-to-one
correspondence as illustrated in FIGS. 24 and 25, whereas each MAC
layer may control one carrier in a one-to-one correspondence, for
some carriers and one MAC layer may control one or more of the
remaining carriers as illustrated in FIGS. 26 and 27.
[0151] The above-described system uses a plurality of carriers,
that is, first to N-th carriers, and the carriers may be contiguous
or non-contiguous irrespective of downlink or uplink. A TDD system
is configured to use N carriers such that downlink transmission and
uplink transmission take place on each carrier, whereas an FDD
system is configured to use a plurality of carriers for each of
downlink transmission and uplink transmission. The FDD system may
support asymmetrical CA in which different numbers of carriers
and/or carriers having different bandwidths are aggregated for
downlink and uplink.
[0152] When the same number of CCs is aggregated for downlink and
uplink, all CCs can be configured with backward compatibility with
the legacy system. However, CCs without backward compatibility are
not excluded from the present invention.
[0153] FIG. 28 illustrates exemplary asymmetrical CA in which five
DL CCs are linked to a single UL CC. This asymmetrical CA may be
set from the perspective of transmitting UCI. Specific UCI (e.g.
ACK/NACK responses) for a plurality of DL CCs are aggregated in a
single UL CC and transmitted. When a plurality of UL CCs is
configured, specific UCI (e.g. ACKs/NACKs for DL CCs) are
transmitted on a predetermined UL CC (e.g., primary CC, primary
cell or PCell). For convenience, if it is assumed that each DL CC
can carry up to two codewords and the number of ACKs/NACKs for each
CC depends on the maximum number of codewords set per CC (for
example, if a BS sets up to two codewords for a specific CC, even
though a specific PDCCH uses only one codeword on the CC, two
ACKs/NACKs are set for the CC), at least two UL ACK/NACK bits are
needed for each DL CC. In this case, to transmit ACKs/NACKs for
data received on five DL CCs on a single UL CC, at least ten
ACK/NACK bits are needed. If a Discontinuous Transmission (DTX)
state is also to be indicated for each DL CC, at least 12 bits
(=5.sup.6=3125=11.61 bits) are required for ACK/NACK transmission.
Since up to two ACK/NACK bits are available in the conventional
PUCCH Formats 1a and 1b, this structure cannot transmit increased
ACK/NACK information. While CA is given as an example of a cause to
increase the amount of UCI, this situation may also occur due to an
increase in the number of antennas and the existence of a backhaul
subframe in a TDD system and a relay system. Like ACK/NACK
transmission, the amount of control information to be transmitted
is also increased when control information related to a plurality
of DL CCs is to be transmitted on a single UL CC. For example,
transmission of CQI/PMI/RI information related to a plurality of DL
CCs may increase UCI payload. While ACK/NACK information related to
codewords is described in the present invention by way of example,
it is obviously to be understood that a transport block
corresponding to a codeword exists and the same is applicable to
ACK/NACK information for transport blocks.
[0154] In FIG. 28, a UL anchor CC (a UL PCC or a UL primary CC) is
a CC that delivers a PUCCH or UCI, determined
cell-specifically/UE-specifically. For example, a UE can determine
a CC for which initial random access is attempted as the primary
CC. A DTX state may be fed back explicitly or may be fed back so as
to share the same state with a NACK.
[0155] In LTE-A, the concept of a cell is used to manage radio
resources. A cell is defined as a combination of downlink resources
and uplink resources. Yet, the uplink resources are not mandatory.
Therefore, a cell may be composed of downlink resources only or
both downlink resources and uplink resources. The linkage between
the carrier frequencies (or DL CCs) of downlink resources and the
carrier frequencies (or UL CCs) of uplink resources may be
indicated by system information. A cell operating in primary
frequency resources (or a PCC) may be referred to as a primary cell
(PCell) and a cell operating in secondary frequency resources (or
an SCC) may be referred to as a secondary cell (SCell). The PCell
is used for a UE to establish an initial connection or re-establish
a connection. The PCell may refer to a cell indicated during
handover. Only one PCell can exist during CA in LTE-A release 10.
The SCell may be configured after an RRC connection is established
and may be used to provide additional radio resources. The PCell
and the SCell may collectively be referred to as a serving cell.
Accordingly, a single serving cell composed of a PCell only exists
for a UE in RRC_Connected state, for which CA is not set or which
does not support CA. On the other hand, one or more serving cells
exist, including a PCell and entire SCells, for a UE in
RRC_CONNECTED state, for which CA is set. For CA, a network may
configure one or more SCells in addition to an initially configured
PCell, for a UE supporting CA during connection setup after an
initial security activation operation is initiated. Therefore, PCC
is interchangeably used with PCell, primary (radio) resources, and
primary frequency resources. Similarly, SCC is used interchangeably
with SCell, secondary (radio) resources, and secondary frequency
resources.
[0156] Now a description will be given of a method for efficiently
transmitting increased UCI with reference to drawings.
Specifically, a new PUCCH format, a signal processing operation,
and a resource allocation method for transmitting increased UCI are
proposed. The new PUCCH format proposed by the present invention is
called CA PUCCH Format or PUCCH Format 3, considering that PUCCH
Format 1 to PUCCH Format 2 are defined in legacy LTE Release 8/9.
The technical features of the proposed PUCCH format may be applied
to any physical channel (e.g. a PUSCH) that can deliver UCI in the
same manner or in a similar manner. For example, an embodiment of
the present invention is applicable to a periodic PUSCH structure
for transmitting control information periodically or a non-periodic
PUSCH structure for transmitting control information
non-periodically.
[0157] The following drawings and embodiments of the present
invention will be described focusing on a case in which the UCI/RS
symbol structure of the legacy LTE PUCCH Format 1/1a/1b (in case of
a normal CP) is used as a subframe-level/slot-level UCI/RS symbol
structure applied to PUCCH Format 3. However, the
subframe-level/slot-level UCI/RS symbol structure of PUCCH Format 3
is defined to provide an example, which should not be construed as
limiting the present invention. The number and positions of UCI/RS
symbols may be changed freely in PUCCH Format 3 of the present
invention according to system design. For example, PUCCH Format 3
according to an embodiment of the present invention may be defined
using the RS symbol structure of the legacy LTE PUCCH Format
2/2a/2b.
[0158] PUCCH Format 3 according to the embodiment of the present
invention may be used to transmit UCI of any type/size. For
example, information such as HARQ ACK/NACK, CQI, PMI, RI, and SR
may be transmitted in PUCCH Format 3 according to the embodiment of
the present invention. This information may have a payload of any
size. For convenience, the following description will focus on
transmission of ACK/NACK information in PUCCH Format 3 according to
the present invention.
[0159] FIGS. 29 to 32 illustrate the structure of PUCCH Format 3
that can be used in the present invention and a signal processing
operation for PUCCH Format 3. Especially, FIGS. 29 to 32 illustrate
a DFT-based PUCCH format. According to the DFT-based PUCCH
structure, a PUCCH is DFT-precoded and spread with a time-domain OC
at an SC-FDMA level, prior to transmission. Hereinafter, the
DFT-based PUCCH format will be referred to as PUCCH Format 3.
[0160] FIG. 29 illustrates an exemplary structure of PUCCH Format 3
using an OC with SF=4. Referring to FIG. 29, a channel coding block
channel-encodes transmission bits a.sub.--0, a.sub.--1, . . . ,
a_M-1 (e.g. multiple ACK/NACK bits), thus creating coded bits (or a
codeword), b.sub.--0, b.sub.--1, . . . , b_N-1. M is the size of
transmission bits and N is the size of coded bits. The transmission
bits include UCI, for example, multiple ACKs/NACKs for a plurality
of data (or PDSCHs) received on a plurality of DL CCs. Herein, the
transmission bits a.sub.--0, a.sub.--1, . . . , a_M-1 are jointly
encoded irrespective of the type, number, or size of UCI that forms
the transmission bits. For example, if the transmission bits
include multiple ACKs/NACKs for a plurality of DL CCs, channel
coding is performed on the entire bit information, rather than per
DL CC or per ACK/NACK bit. A single codeword is generated by
channel coding. Channel coding includes, without being limited to,
repetition, simplex coding, RM coding, punctured RM coding,
tail-biting convolutional coding (TBCC), low-density parity-check
(LDPC) coding, or turbo coding. While not shown, the coded bits may
be rate-matched, taking into account modulation order and the
amount of resources. The rate matching function may be incorporated
into the channel coding block or implemented in a separate
functional block. For example, the channel coding block may produce
a single codeword by performing (32, 0) RM coding on a plurality of
pieces of control information and may subject the single codeword
to cyclic buffer rate-matching.
[0161] A modulator generates modulation symbols c.sub.--0,
c.sub.--1, . . . , c_L-1 by modulating the coded bits b.sub.--0,
b.sub.--1, . . . , b_M-1. L is the size of modulation symbols. A
modulation scheme is performed by changing the amplitude and phase
of a transmission signal. The modulation scheme may be n-phase
shift keying (n-PSK) or n-quadrature amplitude modulation (QAM) (n
being 2 or a larger integer). More specifically, the modulation
scheme may be BPSK, QPSK, 8-PSK, QAM, 16-QAM, or 64-QAM.
[0162] A divider divides the modulation symbols c.sub.--0,
c.sub.--1, . . . , c_L-1 into slots. The order/pattern/scheme of
dividing modulation symbols into slots is not limited to a specific
one. For instance, the divider may divide the modulation symbols
into slots, sequentially starting from the first modulation symbol
(localized scheme). In this case, the modulation symbols c.sub.--0,
c.sub.--1, . . . , c_L/2-1 may be allocated to slot 0 and the
modulation symbols c_L/2, c_L/2+1, . . . , c_L-1 may be allocated
to slot 1. When the modulation symbols are allocated to the slots,
they may be interleaved (or permuted). For example, even-numbered
modulation symbols may be allocated to slot 0 and odd-numbered
modulation symbols may be allocated to slot 1. Division may precede
modulation.
[0163] A DFT precoder performs DFT precoding (e.g. 12-point DFT) on
the modulation symbols allocated to the slots in order to generate
a single carrier waveform. Referring to FIG. 29, the modulation
symbols c.sub.--0, c.sub.--1, . . . , c_L/2-1 allocated to slot 0
are DFT-precoded to d.sub.--0, d.sub.--1, . . . , d_L/2-1 and the
modulation symbols c_L/2, c_L/2+1, . . . , c_L-1 allocated to slot
1 are DFT-precoded to d_L/2, d_L/2+1, . . . , d_L-1. DFT precoding
may be replaced with another linear operation (e.g. Walsh
precoding).
[0164] A spreading block spreads DFT signals at an SC-FDMA symbol
level (in the time domain). The SC-FDMA symbol-level time-domain
spreading is performed using a spreading code (sequence). The
spreading code includes a quasi-orthogonal code and an orthogonal
code. The quasi-orthogonal code includes, without being limited to,
a PN (pseudo noise) code. The orthogonal code includes, without
being limited to, a Walsh code and a DFT code. While an orthogonal
code is taken as a main example of the spreading code herein for
convenience, the orthogonal code may be replaced with a
quasi-orthogonal code. The maximum value of a spreading code size
(or a spreading factor (SF)) is limited by the number of SC-FDMA
symbols used to transmit control information. For example, if four
SC-FDMA symbols carry control information in one slot, an
orthogonal code of length 4, w0, w1, w2, w3 can be used in each
slot. The SF means the degree to which control information is
spread. The SF may be related to the multiplexing order or antenna
multiplexing order of a UE. The SF may be changed to 1, 2, 3, 4, .
. . depending on system requirements. An SF may be predefined
between a BS and a UE or the BS may indicate an SF to the UE by DCI
or RRC signaling. For example, if one of SC-FDMA symbols for
control information is punctured to transmit an SRS, a spreading
code with a decreased SF (e.g. SF=3 instead of SF=4) may be applied
to the control information in a corresponding slot.
[0165] A signal generated from the above operation is mapped to
subcarriers in a PRB and converted to a time-domain signal by IFFT.
A CP is added to the time-domain signal and the resulting SC-FDMA
symbols are transmitted through an RF end.
[0166] On the assumption that ACKs/NACKs are transmitted for five
DL CCs, each operation will be described in greater detail. If each
DL CC can deliver two PDSCHs, ACK/NACK bits for the PDSCHs may be
12 bits, including a DTX state. Given QPSK and time spreading with
SF=4, the size of a coding block (after rate matching) may be 48
bits. The coded bits are modulated to 24 QPSK symbols and the QPSK
symbols are divided into two slots, 12 QPSK symbols for each slot.
The 12 QPSK symbols of each slot are converted into 12 DFT symbols
by 12-point DFT, spread to four SC-FDMA symbols using an OC with
SF=4 in the time domain, and then mapped. Because 12 bits are
transmitted on [2 bits.times.12 subcarriers.times.8 SC-FDMA
symbols], the coding rate is 0.0625 (=12/192). If SF=4, up to four
UEs may be multiplexed per PRB.
[0167] FIG. 30 illustrates an exemplary structure of PUCCH Format 3
using an OC with SF=5.
[0168] The basic signal processing operation is performed in the
same manner as described with reference to FIG. 29 except for the
number and positions of UCI SC-FDMA symbols and RS SC-FDMA symbols.
A spreading block may be generated in advance at the front end of a
DFT precoder.
[0169] In FIG. 30, RSs may be configured in the same configuration
as used in the LTE system. For example, a base sequence may be
cyclically shifted. The multiplexing capacity of a data part is 5
in view of SF=5. However, the multiplexing capacity of an RS part
is determined by a CS interval .DELTA..sub.shift.sup.PUCCH. For
example, given a multiplexing capacity of
12/.DELTA..sub.shift.sup.PUCCH, the multiplexing capacities for the
cases where .DELTA..sub.shift.sup.PUCCH=1,
.DELTA..sub.shift.sup.PUCCH=2, and .DELTA..sub.shift.sup.PUCCH=3
are respectively 12, 6, and 4. In FIG. 30, while the multiplexing
capacity of the data part is 5 due to SF=5, the multiplexing
capacity of the RS part is 4 in case of
.DELTA..sub.shift.sup.PUCCH. Therefore, overall multiplexing
capacity may be limited to the smaller of the two values, 4.
[0170] FIG. 31 illustrates an exemplary structure of PUCCH Format 3
that can increase a multiplexing capacity at a slot level.
[0171] Overall multiplexing capacity can be increased by applying
SC-FDMA symbol-level spreading described with reference to FIGS. 29
and 30 to RSs. Referring to FIG. 31, the multiplexing capacity is
doubled by applying a Walsh cover (or a DFT code cover) within a
slot. As a consequence, the multiplexing capacity is 8 even in case
of .DELTA..sub.shift.sup.PUCCH, thereby preventing a decrease in
the multiplexing capacity of a data part. In FIG. 31, an OC for RSs
may be [y1 y2]=[1 1], [y1 y2]=[1 -1], or their modification (e.g.
[j j] [j -j], [1 j] [1 -j], etc.).
[0172] FIG. 32 illustrates an exemplary structure of PUCCH Format 3
that can increase a multiplexing capacity at a subframe level.
[0173] Without slot-level frequency hopping, use of a Walsh cover
on a slot basis can further double a multiplexing capacity. As
described before, [x1 x2]=[1 1], [1 -1], or a modification thereof
may be used as an OC.
[0174] For reference, the processing operation of PUCCH Format 3 is
not limited to the orders illustrated in FIGS. 29 to 32.
[0175] FIG. 33 illustrates an ACK/NACK information transmission
structure using channel selection to which the present invention is
applied. Referring to FIG. 33, two PUCCH resources or PUCCH
channels (PUCCH resources #0 and #1 or PUCCH channels #0 and #1)
can be set for PUCCH format 1b for 2-bit ACK/NACK information.
[0176] If 3-bit ACK/NACK information is transmitted, 2 bits of the
3-bit ACK/NACK information can be represented according to PUCCH
format 1b and the remaining 1 bit can be represented according to
which one of the two PUCCH resources is selected. For example, 1
bit (2 cases) can be represented by selecting transmission of the
ACK/NACK information using PUCCH resource #0 or transmission of the
ACK/NACK information using PUCCH resource #1. In this manner, the
3-bit ACK/NACK information can be represented.
[0177] Table 11 shows an example of transmission of 3-bit ACK/NACK
information using channel selection on the assumption that two
PUCCH resources are set.
TABLE-US-00011 TABLE 11 Ch1 Ch2 ACK/NACK RS Data RS Data N, N, N 1
1 0 0 N, N, A 1 -j 0 0 N, A, N 1 j 0 0 N, A, A 1 -1 0 0 A, N, N 0 0
1 1 A, N, A 0 0 1 -j A, A, N 0 0 1 j A, A, A 0 0 1 -1
[0178] In Table 11, `A` denotes ACK information and `N` denotes
NACK information or NACK/DTX information. In addition, `1, -1, j
and -j` represent four complex modulated symbols obtained by
modulating 2 bits of information, b(0)b(1), transmitted in a PUCCH
format, according to QPSK. Here, b(0)b(1) correspond binary bits
transmitted using a selected PUCCH resource. For example, b(0)b(1)
can be mapped to a complex modulated symbol and transmitted through
a PUCCH resource.
TABLE-US-00012 TABLE 12 Complex modulated Modulation Binary
transmission bits b(0), b(1) symbol QPSK 0, 0 1 0, 1 -j 1, 0 J 1, 1
-1
[0179] FIG. 34 illustrates an ACK/NACK information transmission
structure using enhanced channel selection to which the present
invention is applied. While FIG. 34 shows that PUCCH #0 and PUCCH
#1 correspond to different time/frequency regions, PUCCH #0 and
PUCCH #1 can be configured to use different codes in the same
time/frequency region. Referring to FIG. 34, two PUCCH resources
(PUCCH resources #0 and #1) can be set for PUCCH format 1a for
1-bit ACK/NACK information transmission.
[0180] If 3-bit ACK/NACK information is transmitted, 1 bit thereof
can be represented using PUCCH format 1a and another 1 bit can be
represented according to which one of the PUCCH resources (PUCCH
resources #0 and #1) is used to transmit the ACK/NACK information.
The remaining 1 bit can be represented based on a reference signal
corresponding to a corresponding PUCCH resource. While the
reference signal is preferably transmitted in the time/frequency
region corresponding to a PUCCH resource (PUCCH resource #0 or #1)
selected first, the reference signal may be transmitted in a
time/frequency region with respect to the PUCCH resource
corresponding thereto.
[0181] That is, 2 bits (4 cases) can be represented by selecting
one of a case in which the ACK/NACK information is transmitted
through PUCCH resource #0 and a reference signal corresponding to
PUCCH resource #0 is transmitted, a case in which the ACK/NACK
information is transmitted through PUCCH resource #1 and a
reference signal corresponding to PUCCH resource #1 is transmitted,
a case in which the ACK/NACK information is transmitted through
PUCCH resource #0 and a reference signal corresponding to PUCCH
resource #1 is transmitted, and a case in which the ACK/NACK
information is transmitted through PUCCH resource #1 and a
reference signal corresponding to PUCCH resource #0 is transmitted.
In this manner, the 3-bit ACK/NACK information can be
represented.
[0182] Table 13 shows an example of transmission of 3-bit ACK/NACK
information using enhanced channel selection on the assumption that
two PUCCH resources are set.
TABLE-US-00013 TABLE 13 Ch1 Ch2 ACK/NACK RS Data RS Data N, N, N 1
1 0 0 N, N, A 1 -1 0 0 N, A, N 0 1 1 0 N, A, A 0 -1 1 0 A, N, N 1 0
0 1 A, N, A 1 0 0 -1 A, A, N 0 0 1 1 A, A, A 0 0 1 -1
[0183] In the case of transmission of 3-bit ACK/NACK information
using enhanced channel selection, shown in Table 13, symbols mapped
to PUCCH resources can be obtained according to BPSK, distinguished
from ACK/NACK information transmission using channel selection,
shown in Table 12. However, complex symbols can be obtained
according to QPSK using PUCCH format 1b, differently from the
example of FIG. 13. In this case, the number of bits that can be
transmitted through the same PUCCH resource can be increased.
[0184] While FIGS. 33 and 34 illustrate a case in which two PUCCH
resources are set for 3-bit ACK/NACK information transmission, the
number of bits of transmitted ACK/NACK information and the number
of PUCCH resources can be varied. Furthermore, the ACK/NACK
information transmission structures can be equally applied to
transmission of uplink control information other than ACK/NACK
information or simultaneous transmission of ACK/NACK information
and uplink control information.
[0185] Table 14 shows an example of transmission of six ACK/NACK
states using channel selection when two PUCCH resources are
set.
TABLE-US-00014 TABLE 14 b(0), HARQ-ACK(0), HARQ-ACK(1)
n.sup.(1).sub.PUCCH b(1) ACK, ACK n.sup.(1).sub.PUCCH, 1 1, 1 ACK,
NACK/DTX n.sup.(1).sub.PUCCH, 0 0, 1 NACK/DTX, ACK
n.sup.(1).sub.PUCCH, 1 0, 0 NACK/DTX, NACK n.sup.(1).sub.PUCCH, 1
1, 0 NACK, DTX n.sup.(1).sub.PUCCH, 0 1, 0 DTX, DTX N/A N/A
[0186] Table 15 shows an example of transmission of eleven ACK/NACK
states using channel selection when three PUCCH resources are
set.
TABLE-US-00015 TABLE 15 HARQ-ACK(0), HARQ-ACK(1), b(0), HARQ-ACK(2)
n.sup.(1).sub.PUCCH b(1) ACK, ACK, ACK n.sup.(1).sub.PUCCH, 2 1, 1
ACK, ACK, NACK/DTX n.sup.(1).sub.PUCCH, 1 1, 1 ACK, NACK/DTX, ACK
n.sup.(1).sub.PUCCH, 0 1, 1 ACK, NACK/DTX, NACK/DTX
n.sup.(1).sub.PUCCH, 0 0, 1 NACK/DTX, ACK, ACK n.sup.(1).sub.PUCCH,
2 1, 0 NACK/DTX, ACK, NACK/DTX n.sup.(1).sub.PUCCH, 1 0, 0
NACK/DTX, NACK/DTX, ACK n.sup.(1).sub.PUCCH, 2 0, 0 DTX, DTX, NACK
n.sup.(1).sub.PUCCH, 2 0, 1 DTX, NACK, NACK/DTX
n.sup.(1).sub.PUCCH, 1 1, 0 NACK, NACK/DTX, NACK/DTX
n.sup.(1).sub.PUCCH, 0 1, 0 DTX, DTX, DTX N/A N/A
[0187] Table 16 shows an example of transmission of twenty ACK/NACK
states using channel selection when four PUCCH resources are
set.
TABLE-US-00016 TABLE 16 HARQ-ACK(0), HARQ-ACK(1), b(0),
HARQ-ACK(2), HARQ-ACK(3) n.sup.(1).sub.PUCCH b(1) ACK, ACK, ACK,
ACK n.sup.(1).sub.PUCCH, 1 1, 1 ACK, ACK. ACK, NACK/DTX
n.sup.(1).sub.PUCCH, 1 1, 0 NACK/DTX, NACK/DTX, NACK, DTX
n.sup.(1).sub.PUCCH, 2 1, 1 ACK, ACK, NACK/DTX, ACK
n.sup.(1).sub.PUCCH, 1 1, 0 NACK, DTX, DTX, DTX
n.sup.(1).sub.PUCCH, 0 1, 0 ACK, ACK, NACK/DTX, NACK/DTX
n.sup.(1).sub.PUCCH, 1 1, 0 ACK, NACK/DTX, ACK, ACK
n.sup.(1).sub.PUCCH, 3 0, 1 NACK/DTX, NACK/DTX, NACK/DTX, NACK
n.sup.(1).sub.PUCCH, 3 1, 1 ACK, NACK/DTX, ACK, NACK/DTX
n.sup.(1).sub.PUCCH, 2 0, 1 ACK, NACK/DTX, NACK/DTX, ACK
n.sup.(1).sub.PUCCH, 0 0, 1 ACK, NACK/DTX, NACK/DTX, NACK/DTX
n.sup.(1).sub.PUCCH, 0 1, 1 NACK/DTX, ACK, ACK, ACK
n.sup.(1).sub.PUCCH, 3 0, 1 NACK/DTX, NACK, DTX, DTX
n.sup.(1).sub.PUCCH, 1 0, 0 NACK/DTX, ACK, ACK, NACK/DTX
n.sup.(1).sub.PUCCH, 2 1, 0 NACK/DTX, ACK, NACK/DTX, ACK
n.sup.(1).sub.PUCCH, 3 1, 0 NACK/DTX, ACK, NACK/DTX, NACK/DTX
n.sup.(1).sub.PUCCH, 1 0, 1 NACK/DTX, NACK/DTX, ACK, ACK
n.sup.(1).sub.PUCCH, 3 0, 1 NACK/DTX, NACK/DTX, ACK, NACK/DTX
n.sup.(1).sub.PUCCH, 2 0, 0 NACK/DTX, NACK/DTX, NACK/DTX, ACK
n.sup.(1).sub.PUCCH, 3 0, 0 DTX, DTX, DTX, DTX N/A N/A
[0188] A UE collects responses to cases that require a plurality of
ACK/NACK feedbacks received from a PCell DL CC and SCell DL CCs
(through multiplexing, bundling, etc., for example) and transmits
the responses using a PUCCH in a UL CC in a PCell.
[0189] Cases that require HARQ ACK/NACK feedback for a DL CC can
include the following three.
[0190] First, HARQ ACK/NACK feedback can be required in the case of
Table 17.
TABLE-US-00017 TABLE 17 For a PDSCH(s) transmission indicated by
the detection of a corresponding PDCCH(s) in subframe(s) n - k,
where k .di-elect cons. K and K is a set of M elements {k.sub.0,
k.sub.1, . . . k.sub.M-1} depending on the subframe n and the UL-DL
configuration.
[0191] Table 17 represents a PDSCH(s) that requires normal A/N
feedback. The PDSCH can be present in DL PCell and SCells. This
PDSCH is called `PDSCH with PDCCH` in the following description for
convenience.
[0192] HARQ ACK/NACK feedback can be required in the case of Table
18.
TABLE-US-00018 TABLE 18 For a PDCCH(s) indicating downlink SPS
release in subframe(s) n - k, where k .di-elect cons. K and K is a
set of M elements {k.sub.0, k.sub.1, . . . k.sub.M-1} depending on
the subframe n and the UL-DL configuration.
[0193] Table 18 represents A/N feedback for PDCCH(s) for SPS
release. Here, only one PDSCH without corresponding PDCCH can be
present over one or more DL cells in one subframe. A/N feedback for
PDCCH(s) indicating DL SPS (semi-persistent scheduling) release may
be performed whereas A/N feedback for PDCCH(s) indicating DL SPS
activation may not be performed. This PDCCH can be present only in
a DL PCell. This case is referred to as `DL SPS release` in the
following description for convenience.
[0194] HARQ ACK/NACK feedback can be required in the case of Table
19.
TABLE-US-00019 TABLE 19 For a PDSCH(s) transmission where there is
not a corresponding PDCCH detected in subframe(s) n - k, where k
.di-elect cons. K and K is a set of M elements {k.sub.0, k.sub.1, .
. . k.sub.M-1} depending on the subframe n and the UL-DL
configuration.
[0195] Table 19 represents A/N feedback for PDSCH(s) without
PDCCH(s) indicating SPS. Only one PDSCH without corresponding PDCCH
can be present over one or more DL cells in one subframe. This
PDSCH can be present only in a DL PCell. This case is referred to
as `DL SPS` in the following description for convenience.
[0196] HARQ ACK/NACK feedback events described using Tables 17, 18
and 19 are exemplary and HARQ ACK/NACK feedback may be performed
when other events are generated.
[0197] In Tables 17, 18 and 19, M denotes the number of elements of
a set K and HARQ-ACK transmission timing for DL reception and K can
be represented according to subframe position (n) and TDD UL-DL
configuration, as shown in Table 20.
TABLE-US-00020 TABLE 20 UL-DL Subframe n Configuration 0 1 2 3 4 5
6 7 8 9 0 -- -- 6 -- 4 -- -- 6 -- 4 1 -- -- 7, 6 4 -- -- -- 7, 6 4
-- 2 -- -- 8, 7, 4, 6 -- -- -- -- 8, 7, 4, 6 -- -- 3 -- -- 7, 6, 11
6, 5 5, 4 -- -- -- -- -- 4 -- -- 12, 8, 7, 11 6, 5, 4, 7 -- -- --
-- -- -- 5 -- -- 13, 12, 9, 8, 7, 5, 4, 11, 6 -- -- -- -- -- -- --
6 -- -- 7 7 5 -- -- 7 7 --
[0198] Table 20 can be represented as FIG. 35 or 37.
[0199] FIGS. 35 and 37 illustrate ACK/NACK feedback for DL
subframes according to Table 20 when ACK/NACK feedback is performed
in UL subframes in the second of two frames.
[0200] For example, in the case of UL-DL configuration #0 shown in
FIG. 35, six UL subframes are present in one frame. In the first UL
subframe of the second frame, ACK/NACK for a special subframe (of
the first frame) corresponding to the sixth subframe from the first
UL subframe is fed back. In the second UL subframe of the second
frame, no ACK/NACK is fed back. In the third UL subframe of the
second frame, ACK/NACK for a DL subframe corresponding to the
fourth subframe from the third UL subframe and being prior to the
third UL subframe is fed back. In the fourth UL subframe of the
second frame, ACK/NACK for a special subframe corresponding to the
sixth subframe from the fourth UL subframe and being prior to the
fourth UL subframe is fed back. In the fifth UL subframe of the
second frame, no ACK/NACK is fed back. In the sixth UL subframe of
the second frame, ACK/NACK for a DL subframe corresponding to the
fourth subframe from the sixth UL subframe and being prior to the
sixth UL subframe is fed back.
[0201] In the case of UL-DL configuration #1 shown in FIG. 35, four
UL subframes are present in one frame. In the first UL subframe of
the second frame, ACK/NACK for a DL subframe (of the first frame),
which is the seventh one from the first UL subframe, and ACK/NACK
for a special subframe (of the first frame), which is the sixth one
from the first UL subframe, are multiplexed or bundled and fed
back. In the second UL subframe, ACK/NACK for a DL subframe (of the
first frame), which is the fourth one from the second UL subframe,
is fed back. In the third UL subframe, ACK/NACK for a DL subframe,
which is the seventh one from the third UL subframe, and ACK/NACK
for a special subframe, which is the sixth one from the third UL
subframe, are multiplexed or bundled and fed back. In the fourth UL
subframe, ACK/NACK for a DL subframe, which is the fourth subframe
from the fourth UL subframe, is fed back. While description of
operations in other UL-DL configurations is omitted for
convenience, ACK/NACK feedback is performed in the same manner as
in UL-DL configurations #0 and #1.
[0202] That is, the position of a DL subframe corresponding to
ACK/NACK fed back in each UL subframe depends on TDD UL-DL
configuration and UL subframe position in TDD.
[0203] In FDD, M is always 1 and K is always {k.sub.0}={4}.
[0204] In the meantime, cross-scheduling from a PCell to an
SCell(s) may be supported whereas cross-scheduling from the
SCell(s) to the PCell may not be supported.
[0205] When a cell(s) cross-scheduled from another cell is present,
additional PDSCH allocation may not be performed in the cell(s).
That is, a specific cell can be cross-scheduled only from a
specific cell.
[0206] Cross-carrier scheduling is a scheme in which a control
channel transmitted through a primary CC schedules a data channel
transmitted through the primary CC or another CC using a carrier
indicator field (CIF).
[0207] FIG. 36 illustrates cross-carrier scheduling. In FIG. 36,
the number of cells (or CCs) allocated to a relay node is 3 and
cross-carrier scheduling is performed using the CIF as described
above. Here, DL cell (or DL CC) #A is assumed as a primary DL CC
(i.e. primary cell; PCell) and other CCs #B and #C are assumed as
secondary CCs (i.e. secondary cells; SCells).
[0208] It is assumed that a UE is configured to performed
communication through two CCs in the following.
[0209] One of the two CCs is referred to as a primary CC (PCC or
PCell) and the other is referred to as a secondary CC (SCC or
SCell).
[0210] In addition, it is assumed that the UE receives various
control signals including a PDCCH through the PCell and data
transmission and reception of the SCell is cross-carrier scheduled
according to a control signal in the PCell.
[0211] The following description is given based on an FDD system
using CC #1 (DL PCell, LTE-A frequency band), CC #3 (UL PCell,
LTE-A frequency band) and CC #2 (SCell, unlicensed band).
[0212] Intra-band CA is considered first for a CA environment, in
general. A band used in intra-band and inter-band refers to an
operating band and can be defined as follows.
[0213] That is, the operating band represents a frequency range in
E-UTRA operating in a paired or unpaired manner and can be defined
as a specific set according to technical requirements.
[0214] For example, operating bands used in LTE can be defined as
shown in Table 21.
TABLE-US-00021 TABLE 21 Uplink (UL) operating band Downlink (DL)
operating band E-UTRA BS receive BS transmit Operating UE transmit
UE receive Duplex Band
F.sub.UL.sub.--.sub.low-F.sub.UL.sub.--.sub.high
F.sub.DL.sub.--.sub.low-F.sub.DL.sub.--.sub.high Mode 1 1920
MHz-1980 MHz 2110 MHz-2170 MHz FDD 2 1850 MHz-1910 MHz 1930
MHz-1990 MHz FDD 3 1710 MHz-1785 MHz 1805 MHz-1880 MHz FDD 4 1710
MHz-1755 MHz 2110 MHz-2155 MHz FDD 5 824 MHz-849 MHz 869 MHz-894
MHz FDD 6.sup.1 830 MHz-840 MHz 875 MHz-885 MHz FDD 7 2500 MHz-2570
MHz 2620 MHz-2690 MHz FDD 8 880 MHz-915 MHz 925 MHz-960 MHz FDD 9
1749.9 MHz-1784.9 MHz 1844.9 MHz-1879.9 MHz FDD 10 1710 MHz-1770
MHz 2110 MHz-2170 MHz FDD 11 1427.9 MHz-1447.9 MHz 1475.9
MHz-1495.9 MHz FDD 12 698 MHz-716 MHz 728 MHz-746 MHz FDD 13 777
MHz-787 MHz 746 MHz-756 MHz FDD 14 788 MHz-798 MHz 758 MHz-768 MHz
FDD 15 Reserved Reserved FDD 16 Reserved Reserved FDD 17 704
MHz-716 MHz 734 MHz-746 MHz FDD 18 815 MHz-830 MHz 860 MHz-875 MHz
FDD 19 830 MHz-845 MHz 875 MHz-890 MHz FDD 20 832 MHz-862 MHz 791
MHz-821 MHz 21 1447.9 MHz-1462.9 MHz 1495.9 MHz-1510.9 MHz FDD . .
. 33 1900 MHz-1920 MHz 1900 MHz-1920 MHz TDD 34 2010 MHz-2025 MHz
2010 MHz-2025 MHz TDD 35 1850 MHz-1910 MHz 1850 MHz-1910 MHz TDD 36
1930 MHz-1990 MHz 1930 MHz-1990 MHz TDD 37 1910 MHz-1930 MHz 1910
MHz-1930 MHz TDD 38 2570 MHz-2620 MHz 2570 MHz-2620 MHz TDD 39 1880
MHz-1920 MHz 1880 MHz-1920 MHz TDD 40 2300 MHz-2400 MHz 2300
MHz-2400 MHz TDD 41 2496 MHz-2690 MHz 2496 MHz-2690 MHz TDD Note
.sup.1Band 6 is not applicable.
[0215] Intra-band CA refers to positioning of a plurality of DL CCs
and/or UL CCs in the frequency domain in a contiguous or
non-contiguous manner.
[0216] In other words, intra-band CA can refer to positioning of
carrier frequencies of a plurality of DL CCs and/or UL CCs in the
same (operating) band.
[0217] Accordingly, a plurality of CCs can be designed on the
assumption that the CCs have similar propagation characteristics
through intra-band CA. The propagation characteristics include
propagation/path delay, propagation/path loss, fading channel
impact, etc. depending on frequency (or center frequency).
[0218] The UE sets uplink transmission timing for a primary cell UL
CC.
[0219] Uplink transmission timing for the secondary cell
corresponds to uplink transmission timing for the primary cell on
the above assumption (that CCs have similar propagation/path
delays). However, PRACH (physical random access channel)
transmission timing may be different.
[0220] Through the above-described procedure, inter-cell UL
subframe boundaries in the UE can be adjusted to correspond to each
other. Accordingly, the UE can perform communication in a CA
environment using a single radio frequency (RF) terminal.
[0221] However, one or more cells may not be contiguous to other
cells in the frequency domain in a CA environment because of
problems with respect to frequency allocation to mobile carriers
(allocation of remaining frequencies, reuse of frequencies
previously used for other purposes, etc.) for mobile
communication.
[0222] For example, if two cells construct a CA environment, the
carrier frequency of one cell can be 800 MHz (UL/DL) and the
carrier frequency of the other can be 2.5 GHz (UL/DL).
[0223] Alternatively, the carrier frequency of one cell can be 800
MHz (UL/DL) and the carrier frequency of the other can be 2.6 GHz
(UL/DL).
[0224] Otherwise, the carrier frequency of one cell can be 700 MHz
(UL/DL) and the carrier frequency of the other can be
1.7(UL)/2.1(DL) GHz (TDD). Here, the carrier frequency refers to
the carrier frequency of a DL CC or UL CC.
[0225] An environment in which CCs are spaced apart in the
frequency domain, as described above, can be referred to as
inter-band CA.
[0226] In other words, carrier frequencies of a plurality of DL CCs
and/or UL CCs are present in different bands.
[0227] In the inter-band CA environment, the assumption that cells
have similar propagation characteristics cannot be maintained.
[0228] That is, it cannot be assumed that inter-cell (UL) subframe
boundaries are adjusted to correspond to each other in the
inter-band CA environment. Accordingly, cells need different uplink
transmission timings and the UE may use a plurality of RF terminals
to perform communication in a CA environment.
[0229] Time for detecting a PDSCH (with or without corresponding
PDCCH) or PDCCH indicating DL SPS release, which corresponds to
PUCCH transmission timing (n-th subframe), can be defined as
follows.
[0230] A HARQ-ACK response to a PDCCH or PDSCH indicating DL SPS
release in subframe n-4 is transmitted through a PUCCH in subframe
n in an FDD environment.
[0231] HARQ-ACK responses to a PDCCH and/or PDSCH indicating DL SPS
release in subframe n-4 are transmitted through a PUCCH in subframe
n in a TDD environment. Here, k can depend on TDD UL/DL
configuration and subframe position in the TDD UL/DL configuration
and have one or more values as a set K (K={k.sub.0, k.sub.1, . . .
, k.sub.M-1,}) in a specific subframe. In other words, a single
PUCCH can include HARQ-ACK responses to one or more PDCCHs and/or a
PDSCHs indicating DL SPS release. The set K can be configured as
shown in Table 20.
[0232] A DAI (UL-DL configurations #1 to #6) in DCI format
1/1A/1B/1D/2/2A/2B/2C of a PDCCH can represent the accumulative
number of PDCCHs with assigned PDSCH transmission in subframe n-k
in each serving cell and a PDCCH indicating DL SPS release.
[0233] FIG. 37 illustrates a PDSCH or a PDCCH in subframe n-k
corresponding to PUCCH transmission in subframe n for DCI format
1/1A/1B/1D/2/2A/2B/2C. Here, k can depend on TDD UL/DL
configuration and subframe position in the TDD UL/DL configuration
and have one or more values as a set K (K={k.sub.0, k.sub.1, . . .
, k.sub.M-1}) in a specific subframe. In other words, a single
PUCCH can include HARQ-ACK responses to one or more PDCCHs and/or
PUSCHs indicating DL SPS release. The set K can be configured as
shown in Table 20.
[0234] DCI format 0 or DCI format 4 detection time corresponding to
PUSCH transmission time (n-th subframe) can be defined as
follows.
[0235] DCI format 0 or DCI format 4 in subframe n-k' represents
PUSCH allocation in subframe n in TDD.
[0236] Here, DAI, V.sub.DAI.sup.UL (UL-DL configurations #1 to #6),
represents the total number of subframes with PDCCH transmission
with DCI format 0 or 4 and with PDCCH indicating downlink SPS
release within subframe n-k'.
[0237] Table 22 shows uplink information regarding index k' for
TDD.
TABLE-US-00022 TABLE 22 TDD UL/DL subframe number n Configuration 0
1 2 3 4 5 6 7 8 9 1 6 4 6 4 2 4 4 3 4 4 4 4 4 4 5 4 6 7 7 5 7 7
[0238] FIG. 38 illustrates PDCCH subframe n-k' through which DCI
format 0/4 for PUSCH allocation in subframe n is transmitted.
[0239] PUSCH transmission time corresponding to PDCCH or PHICH
detection time (n-th subframe) can be defined as follows.
[0240] For FDD and normal HARQ operation, a PDCCH with DCI format 0
or DCI format 4 and/or PHICH transmission in subframe n are
associated with a PUSCH in subframe n+4
[0241] For FDD and subframe bundling operation, a PDCCH with DCI
format 0 in subframe n and/or PHICH transmission in subframe n-5
are associated with the first PUSCH in subframe n+4.
[0242] For TDD, normal HARQ operation and UL/DL configurations #1
to #6, a PDCCH with a DCI format and/or PHICH transmission in
subframe n are associated with a PUSCH in subframe n+k.
[0243] For TDD, normal HARQ operation and UL/DL configuration #0, a
PDCCH with a DCI format and/or PHICH transmission in subframe n are
associated with (1) a PUSCH in subframe n+k when the MSB of the UL
index is set to 1 in the PDCCH with uplink DCI format or the PHICH
is received in subframe n=0 or 5 of the resource corresponding to
I.sub.PHICH=0, (2) a PUSCH in subframe n+7 when the LSB of the UL
index in DCI format 0 or DCI format 4 is set to 1, the PHICH is
received in subframe n=0 or 5 of the resource corresponding to
I.sub.PHICH=0 or the PHICH is received in subframe n=1 or 6 and (3)
a PUSCH in subframes n+k and n+7 when both the MSB and LSB of the
UL index in the PDCCH using the uplink DCI format are set in
subframe n.
[0244] For TDD, subframe bundling operation and UL/DL
configurations #0 to #6, a PDCCH with DCI format 0 in subframe n
and/or PHICH transmission in subframe n-1 are associated with the
first PUSCH in subframe n+k.
[0245] A PDCCH with DCI format 0 in subframe n and/or PHICH
transmission in subframe n-1 can be associated with (1) the first
PUSCH in subframe n+k when the MSB of the UL index in DCI format 0
is set to 1 or I.sub.PHICH=0 for TDD, subframe bundling operation
and UL/DL configuration #0 and (2) a PUSCH in subframe n+7 when the
LSB of the UL index in the PDCCH using DCI format 0 is set to 1 or
I.sub.PHICH=0 for TDD, UL/DL configuration #0 and subframe bundling
operation.
[0246] Table 23 shows the value k TDD configurations #0 to #6.
TABLE-US-00023 TABLE 23 TDD UL/DL subframe number n Configuration 0
1 2 3 4 5 6 7 8 9 0 4 6 4 6 1 6 4 6 4 2 4 4 3 4 4 4 4 4 4 5 4 6 7 7
7 7 5
[0247] Table 23 shows the value k TDD configurations #0, #1 and
#6.
TABLE-US-00024 TABLE 24 TDD UL/DL subframe number n Configuration 0
1 2 3 4 5 6 7 8 9 0 9 6 9 6 1 2 3 2 3 6 5 5 6 6 8
[0248] FIG. 39 illustrates subframe n+k to which a PUSCH is
allocated when DCI format 0/4 or a PHICH for a normal HARQ
operation is transmitted in subframe n.
[0249] FIG. 40 illustrates transmission of a PUSCH in subframe n+k
when a PHICH using subframe bundling is transmitted in subframe n-1
in TDD UL/DL configuration #0 and transmission of a PUSCH in
subframe n+k when DCI format 0/4 using subframe bundling is
transmitted in subframe n.
[0250] FIG. 41 illustrates transmission of a PUSCH in subframe n+k
when a PHICH using subframe bundling is transmitted in subframe n-1
in TDD UL/DL configurations #1 to #6 and transmission of a PUSCH in
subframe n+k when DCI format 0/4 using subframe bundling is
transmitted in subframe n.
[0251] PHICH reception time corresponding to PUSCH transmission
time (n-th subframe) can be defined as follows.
[0252] That is, a HARQ-ACK response to a PUSCH in subframe n is
transmitted through a PHICH in subframe n+4 in an FDD
environment.
[0253] A HARQ-ACK response to a PUSCH in subframe n is transmitted
through a PHICH in subframe n+k.sub.PHICH in a TDD environment.
[0254] Table 25 shows k.sub.PHICH in TDD.
TABLE-US-00025 TABLE 25 TDD UL/DL subframe index n Configuration 0
1 2 3 4 5 6 7 8 9 0 4 7 6 4 7 6 1 4 6 4 6 2 6 6 3 6 6 6 4 6 6 5 6 6
4 6 6 4 7
[0255] FIG. 42 illustrates transmission of a HARQ-ACK response to a
PUSCH in subframe n through a PHICH in subframe n+k.sub.PHICH.
[0256] PHICH reception time (n-th subframe) and PUSCH transmission
time corresponding to the above response can be defined as
follows.
[0257] A HARQ-ACK response to a PUSCH in subframe i-4 is received
through a PHICH in subframe i in an FDD environment.
[0258] A HARQ-ACK response to a PUSCH in subframe i-k is received
through a PHICH in subframe i in the case of TDD and UL/DL
configurations #1 to #6.
[0259] In addition, a HARQ-ACK response to a PUSCH in subframe i-k
is received through a PHICH in subframe i in the case of TDD and
UL/DL configuration #0. Here, a HARQ-ACK response to a PUSCH in
subframe i-k can be received through a PHICH in a resource
corresponding to I.sub.PHICH=0 in subframe i and a HARQ-ACK
response to a PUSCH in subframe i-6 can be received through a PHICH
in a resource corresponding to I.sub.PHICH=1 in subframe i.
[0260] Table 26 shows k applied to TDD configurations #0 to #6.
TABLE-US-00026 TABLE 26 TDD UL/DL subframe number i Configuration 0
1 2 3 4 5 6 7 8 9 0 7 4 7 4 1 4 6 4 6 2 6 6 3 6 6 6 4 6 6 5 6 6 6 4
7 4 6
[0261] FIG. 43 shows that a HARQ-ACK response received through a
PHICH in subframe i corresponds to a PUSCH in subframe i-k.
[0262] A description will be given of a PDCCH structure applicable
to the present invention.
[0263] A PDCCH carries a downlink control information (DCI)
message. Here, the DCI message can include resource allocation
information and other control information.
[0264] In general, a plurality of PDCCHs is transmitted in
subframes. Each PDCCH is transmitted using one or more control
channel elements (CCEs) which correspond to nine sets of four
physical resource elements in resource element groups (REGs).
[0265] Four QPSK symbols are respectively mapped to REGs. REs
mapped to reference symbols are not included in REGs, which means
that the number of REGs corresponding to given OFDM symbols depends
on whether or not cell-specific reference signals are present.
[0266] The concept of REGs is applicable to other DCI (e.g. PCFICH,
PHICH, etc.).
[0267] Four PDCCH formats can be supported as shown in Table
27.
TABLE-US-00027 TABLE 27 PDCCH Number of Number Number of format
CCEs(n) of REGs PDCCH bits 0 1 9 72 1 2 18 144 2 4 36 288 3 8 72
576
[0268] CCEs are numbered and used consecutively. A PDCCH with a
format consisting of n CCEs may only start with a CCE with a number
equal to a multiple of n in order to simplify decoding
operation.
[0269] The number of CCEs used for transmission of a particular
PDCCH is determined by the BS according to channel conditions.
[0270] For example, if the PDCCH is intended for a UE with a good
downlink channel, one CCE is likely to be sufficient. However, for
a UE with a poor downlink channel, eight CCEs may be required in
order to achieve sufficient robustness. Furthermore, the power
level of a PDCCH may be adjusted to match the channel
conditions.
[0271] A description will be given of PDCCH transmission and blind
decoding.
[0272] A set of CCE locations in which the UE may find PDCCHs
thereof can be considered a search space. In LTE, the search space
has a different size for each PDCCH format. A dedicated search
space (or UE-specific search space) and a common search space are
present. The dedicated search space is configured individually per
UE and the common search space is applicable to all UEs. The
dedicated search space and the common search space may overlap for
a given UE.
[0273] With a small search space, the BS cannot find CCE resources
to send PDCCHs to all UEs in a given subframe because information
related to some allocated CCE locations is not present for a
specific UE.
[0274] To solve this problem, a UE-specific hopping sequence can be
applied to the starting position of the dedicated search space. The
sizes of the dedicated search space and common search space are
listed in Table 28.
TABLE-US-00028 TABLE 28 Number of Number of PDCCH Number of
candidates in candidates in format CCEs(n) common search space
dedicated search space 0 0 -- 6 1 2 -- 6 2 4 4 2 3 8 2 2
[0275] In order to control the computational load generated due to
the total number of blind decoding attempts, the UE is not required
to simultaneously search for all DCI formats.
[0276] In general, the UE always searches for formats 0 and 1A in
the dedicated search space. Formats 0 and 1A have the same size and
are distinguished by a flag in a message.
[0277] The UE may be required to receive a further format (e.g.
format 1, 1B or 2).
[0278] The UE may be configured to search for formats 1A and 1C in
the common search space.
[0279] In addition, the UE may be configured to search for format 3
or 3A. Formats 3 and 3A which have the same size as formats 0 and
1A and may be distinguished by having CRC scrambled by a different
identity.
[0280] Transmission modes for configuring the multi-antenna
technique and the information content of the different DCI formats
are listed below.
[0281] (1) Transmission mode 1: transmission from a single BS
antenna port
[0282] (2) Transmission mode 2: transmit diversity
[0283] (3) Transmission mode 3: open-loop spatial multiplexing
[0284] (4) Transmission mode 4: closed-loop spatial
multiplexing
[0285] (5) Transmission mode 5: multi-user MIMO
[0286] (6) Transmission mode 6: closed-loop rank-1 precoding
[0287] (7) Transmission mode 7: transmission using UE-specific
reference signals
[0288] A description will be given of configuration of information
content of different DCI formats.
[0289] (1) Format 0: resource grants for PUSCH transmission
[0290] (2) Format 1: resource assignments for single codeword PDSCH
transmission (transmission modes 1, 2 and 7)
[0291] (3) Format 1A: compact signaling of resource assignments for
single codeword PDSCH (all modes)
[0292] (4) Format 1B: compact resource assignments for PDSCH using
rank-1 closed loop precoding (mode 6)
[0293] (5) Format 1C: compact resource assignment for PDSCH (e.g.
paging/broadcast system information)
[0294] (6) Format 1D: compact resource assignments for PDSCH using
multi-user MIMO (mode 5)
[0295] (7) Format 2: resource assignments for PDSCH for closed-loop
MIMO operation (mode 4)
[0296] (8) Format 2A: resource assignments for PDSCH for open-loop
MIMO operation (mode 3)
[0297] (9) Format 3/3A: power control commands for PUCCH and PUSCH
with 2-bit/1-bit power adjustment
[0298] Considering the above, the UE to which carrier aggregation
is not applied may be required to carry out a maximum of forty-four
blind decoding operations in any subframe.
[0299] This does not include checking the same message with
different CRC values, which requires only small additional
computational complexity.
[0300] A description will be given of a PDCCH resource assignment
procedure.
[0301] A control region can consist of a set of CCEs, numbered from
0 to N.sub.CCE,k-1, where N.sub.CCE,k denotes the total number of
CCEs in the control region of subframe k.
[0302] A UE needs to monitor a set of PDCCH candidates for control
information in every non-DRX subframe, where monitoring can imply
attempting to decode each of the PDCCHs in the set according to all
monitored DCI formats.
[0303] The set of PDCCH candidates to be monitored can be defined
in terms of search spaces. Here, search space S.sub.k.sup.(L) at
aggregation level L.epsilon.{1, 2, 4, 8} can be defined by a set of
PDCCH candidates.
[0304] CCEs corresponding to PDCCH candidates m of the search space
S.sub.k.sup.(L) can be determined according to Equation 3.
L{(Y.sub.k+m)mod N.sub.CCE,k/L}+i [Equation 3]
[0305] In Equation 3, i=0, . . . , L-1 and m=0, . . . ,
M.sup.(L)-1. In addition, M.sup.(L) is the number of PDCCH
candidates to monitor in a predetermined search space.
[0306] The UE needs to monitor a UE-specific search space at
aggregation levels 1, 2, 4 and 8 and a common search space at
aggregation levels 4 and 8.
[0307] The common search space and the UE-specific search space may
overlap.
[0308] Aggregation levels defining search spaces are listed in
Table 29. DCI formats that need to be monitored by the UE depend on
the configured transmission mode.
TABLE-US-00029 TABLE 29 Search space S.sub.k.sup.(L) Aggregation
Size Number of PDCCH Type level L [in CCEs] candidates M.sup.(L)
UE- 1 6 6 specific 2 12 6 4 8 2 8 16 2 Common 4 16 4 8 16 2
[0309] For the common search space, Y.sub.k is set to 0 for the two
aggregation levels L=4 and L=8 in Expression 3. For the UE-specific
search space S.sub.k.sup.(L) at aggregation level L, the variable
Y.sub.k is defined using Equation 4.
a k , 1 = d ( n ) , n = 0 , , 61 k = n - 31 + N RB DL N sc RB 2 [
Equation 4 ] ##EQU00002##
[0310] Here, Y.sub.-1=n.sub.RNTI.noteq.0, A=39827, D=65537 and
n.sub.s is the slot number within a radio frame.
[0311] A description will be given of heterogeneous deployments to
which the present invention is applicable.
[0312] Heterogeneous networks can be implemented by placing
low-power nodes throughout a macro-cell layout.
[0313] Interference characteristics in a heterogeneous deployment
are significantly different from those in a homogeneous deployment.
This is described with reference to FIG. 44.
[0314] Referring to FIG. 44(a), a home eNB (HeNB) may interfere
with a macro UE with no access to a closed subscriber group (CGS)
cell.
[0315] Referring to FIG. 44(b), a macro UE may cause severe
interference towards the HeNB.
[0316] Referring to FIG. 44(c), a CGS UE may be interfered by
another CSG HeNB.
[0317] Referring to FIG. 44(d), path-loss based cell association
may improve the uplink at the cost of increasing downlink
interference of non-macro UEs at the cell edge.
[0318] In these scenarios, preliminary results indicate that
methods for handling uplink and downlink interference as well as
L1/L2 control signals, synchronization signals and reference
signals are important. Such methods may operate in time, frequency
and/or spatial domains.
[0319] In macro-pico heterogeneous network scenarios, a macro cell
can cause severe interference to UEs served by a pico cell,
especially, pico UEs at the edge of the serving pico cell. With
time domain ICIC, the interfering macro cell provides a subframe, a
so called Almost Blank subframe (ABS or ABS), protected from the
dominant interference due to the macro cell.
[0320] FIG. 45 illustrates an exemplary configuration of ABS in
macro-pico scenarios.
[0321] Referring to FIG. 45, a macro cell for which subframes #2
and #6 are configured as ABSFs and information related thereto can
be indicated to a pico cell via backhaul. Based on this
information, the pico cell can schedule UEs corresponding thereto,
especially UEs at the boundary of the macro cell and the pico
cell.
[0322] If the UEs are to be scheduled only in ABSFs, CSI
measurement is only performed in the ABSFs. Otherwise, two types of
subframes are configured for CSI measurement such that CSI
measurement can be respectively performed in the normal subframe
and ABSF.
[0323] A description will be given of detailed embodiments with
respect to heterogeneous networks.
[0324] CSG Scenario
[0325] Dominant interference may occur when non-member UEs are in
close proximity to a CSG cell.
[0326] In this case, it may be possible to divert UEs suffering
from inter-cell interference to another E-UTRA carrier or other
RAT.
[0327] Time domain ICIC may be used to allow such non-member UEs to
remain served by the macro cell on the same frequency layer.
[0328] Such interference may be mitigated by the CSG cell utilizing
almost blank subframes to protect subframes of the corresponding
macro cell from the interference.
[0329] A non-member UE may be signaled to utilize protected
resources for cell measurements (RRM), radio link monitoring (RLM)
and CSI measurements for the serving macro cell, allowing a UE to
continue to be served by the macro cell under strong interference
from the CSG cell.
[0330] FIG. 46 illustrates an exemplary CSG scenario.
[0331] Pico Scenario
[0332] Time domain ICIC may be utilized for pico UEs operating at
the edge of a serving pico cell (e.g. for traffic off-loading from
a macro cell to a pico cell).
[0333] Time domain ICIC may be utilized to allow such UEs to remain
served by the pico cell on the same frequency layer.
[0334] Such interference may be mitigated by the macro cell
utilizing almost blank subframes to protect the corresponding
subframes of the pico cell from the interference.
[0335] A UE served by a pico cell can use protected resources for
cell measurements (RRM), radio link monitoring (RLM) and CSI
measurements for the serving pico cell.
[0336] For a UE served by a pico cell, RRM/RLM/CSI measurement
resource restriction may allow more accurate measurement of the
pico cell under strong interference from the macro cell.
[0337] The pico cell may selectively configure the RRM/RLM/CSI
measurement resource restriction only for UEs subject to strong
interference from the macro cell.
[0338] In addition, for a UE served by the macro cell, the network
may configure RRM measurement resource restriction for neighbour
cells in order to facilitate mobility from the macro cell to the
pico cell.
[0339] FIG. 47 illustrates an example of the above-described pico
scenario.
[0340] An IE can provide information about which subframe is
configured as an almost blank subframe by a BS and transmitted and
which subset of almost blank subframes is configured for
measurements for a UE.
[0341] Here, almost blank subframes correspond to subframes with
reduced power on some physical channels and/or reduced
activity.
[0342] Table 30 shows ABS information.
TABLE-US-00030 IE type and IE/Group Name Presence Range reference
Semantics description CHOICE ABS Information M >FDD >>ABS
Pattern Info M BIT STRING Each position in the (SIZE(40)) bitmap
represents a subframe, for which value "1" indicates `blanked in
DL` and value "0" indicates `not blanked in DL`. The first position
of the ABS pattern corresponds to subframe 0 in a radio frame where
SFN = 0. The ABS pattern is continuously repeated in all radio
frames. The maximum number of subframes is 40. >>Number Of
Cell- M ENUMERATED P(number of antenna specific Antenna Ports (1,
2, 4, . . .) ports for cell - specific reference signals) defined
in TS 36.211 [10] >>Measurement Subset M BIT STRING Indicates
a subset of the (SIZE(40)) ABS Pattern Info above, and is used to
configure specific measurements towards the UE. >TDD >>ABS
Pattern Info M BIT STRING Each position in the (1 . . . 70) bitmap
represents a subframe for which value "1" indicates `blanked in DL`
and value "0" indicates `not blanked in DL`. The maximum number of
subframes depends on UL/DL subframe configuration. The maximum
number of subframes is 20 for UL/DL subframe configuration 1~5; 60
for UL/DL subframe configuration 6; 70 for UL/DL subframe
configuration 0. UL/DL subframe configuration defined in TS 36.211
[10]. The first position of the ABS pattern corresponds to subframe
0 in a radio frame where SFN = 0. The ABS pattern is continuously
repeated in all radio frames, and restarted each time SFN = 0.
>>Number Of Cell- M ENUMERATED P(number of antenna specific
Antenna Ports (1, 2, 4, . . .) ports for cell- specific reference
signals) defined in TS 36.211 [10] >>Measurement Subset M BIT
STRING Indicates a subset of the (1 . . . 70) ABS Pattern Info
above, and is used to configure specific measurements towards the
UE >ABS Inactive M NULL Indicates that interference coordination
by means of almost blank sub frames is not active
[0343] Referring to FIG. 30, the maximum number of subframes of an
ABS pattern may be 20 for UL/DL subframe configurations #1 to #5,
60 for UL/DL subframe configuration #6 or 70 for UL/DL
configuration #0.
[0344] Since the duration of an LTE subframe is 1 ms, the ABS
pattern is 20 ms, 60 ms or 70 ms.
[0345] That is, an ABS can have periodicity of 20 ms for UL/DL
subframe configurations #1 to #5, 60 ms for UL/DL subframe
configuration #6 and 70 ms for UL/DL configuration #0.
[0346] The ABS Status IE is used to aid the BS in designating ABS
to evaluate the need for modification of the ABS pattern.
[0347] Information related thereto is shown in Table 31.
TABLE-US-00031 TABLE 31 IE type and IE/Group Name Presence Range
reference Semantics description DL ABS status M INTEGER Percentage
of resource blocks (0 . . . 100) of ABS allocated for UEs protected
by ABS from inter- cell interference. This includes resource blocks
of ABS unusable due to other reasons. The denominator of the
percentage calculation is indicated in the Usable ABS Information.
CHOICE Usable ABS M Information >FDD >>Usable ABS Pattern
M BIT STRING Each position in the bitmap Info (SIZE(40)) represents
a subframe, for which value "1" indicates `ABS that has been
designated as protected from inter - cell interference` and value
"0" indicates `ABS that is not usable as protected ABS from
inter-cell interference`. The pattern represented by the bitmap is
a subset of, or the same as, the corresponding ABS Pattern InfoIE
conveyed in the LOAD INDICATION message. >TDD >> Usable
ABS Pattern M BIT STRING Each position in the bitmap Info (1 . . .
70) represents a subframe, for which value "1" indicates `ABS that
has been designated as protected from inter-cell interference` and
value "0" indicates `ABS that is not usable as protected ABS from
inter-cell interference`. The pattern represented by the bitmap is
a subset of, or the same as, the corresponding ABS Pattern Info IE
conveyed in the LOAD INDICATION message.
[0348] When ABSs are used, it is necessary to discriminate ABSs
from non-ABSs when a UE measures RSRP (reference signal received
power), RSRQ (reference signal received quality), etc. and performs
radio link monitoring.
[0349] That is, when ABSs are used, the UE is required to perform
measurement only in specific subframe sets (e.g. ABSs or non-ABSs)
rather than all subframes.
[0350] Time domain measurement resource restriction associated with
ABSs is given in such a manner that an ABS pattern has 40 bits for
FDD, 20 bits for TDD configurations #1 to #5, 70 bits for TDD
configuration #0 and 60 bits for TDD configuration #6 and thus have
periodicity of 40 ms, 20 ms, 70 ms and 60 ms.
[0351] The UE can be configured with resource-restricted CSI
measurement if subframe sets C.sub.CSI,0 and C.sub.CSI,1 are
configured by higher layers.
[0352] IE MeasSubframePattern can be used to specify time domain
measurement resource restriction.
[0353] The first/leftmost bit corresponds to the subframe #0 of the
radio frame satisfying SFN mod x=0 (where x is the size of the bit
string devided by 10). Here, "1" represents that the corresponding
subframe is used for measurement.
[0354] MeasSubframePattern information element is shown in Table
32.
TABLE-US-00032 TABLE 32 MeasSubframePattern information element --
ASN1START MeasSubframePattern-r10::= CHOICE {
SubframePatternFDD-r10 BIT STRING (SIZE(40)),
SubframePatternTDD-r10 CHOICE { SubframeConfig1-5-r10 BIT STRING
(SIZE(20)), SubframeConfig0-r10 BIT STRING (SIZE(70)),
SubframeConfig6-r10 BIT STRING (SIZE(60)), } } -- ASN1STOP
[0355] A subframe pattern for the time domain measurement resource
restriction with respect to ABS can be configured in
CQI-ReportConfig from among radio resource control information
elements of Table 32.
[0356] IE CQI-ReportConfig can be used to specify CQI reporting
configuration. Fields added for LTE-A release 10 CQI-ReportConfig
are shown in Table 33.
TABLE-US-00033 TABLE 33 CQI-ReportConfig-r10 ::= SEQUENCE {.1
cqi-ReportModeA perio dic-r10 ENUMERATED {,1 rm12, rm20, rm22,
rm30, rm31,.1 spare3, spare2, spare1} OPTIONAL -- Need OR.1
nomPDSCH-RS-EPRE-Offset-r10 INTEGER (-1..6)..1
cqi-ReportPERIODIC-R10 CQI-ReportPeriodic-r10 OPTIONAL -- Need ON.1
aperiodicCSI-Trig ger-10 SEQUENCE { .1 trigger1-r10 BIT STRING
(SIZE (8))..1 trigger2-r10 BIT STRING (SIZE (8)).1 } OPTIONAL --
Need ON.1 pmi-RI-Report-r9 ENUMERATED {setup} OPTIONAL -- Cond
PMIRI.1 csi-SubframePatternConfig-r10 CHOICE {.1 release NULL..1
setup SEQUENCE {.1 csi-SubframePattern-r10 SEQUENCE {.1
csi-SubframeSet1-r10 MeasSubframePattern-r10,.1
csi-SubframeSet2-r10 MeasSubframePattern-r10,1 },.1
cqi-ReportPeriodicIndex-r10 SEQUENCE{.1 cqi-pmi-ConfigIndex2-r10
INTEGER (0..1023)..1 ri-ConfigIndex2-r10 INTEGER (0..1023) OPTIONAL
-- Need OR.1 } OPTIONAL -- Cond Periodic.1 }.1 } OPTIONAL -- Need
ON.1 }.1 SEQUENCE {.1 CQI-ReportConfigSCell-r10 ::= ENUMERATED {.1
cqi-ReportModeA periodic-r10 rm12, rm20, rm22, rm30, rm31,.1
spare3, spare2, spare1} OPTIONAL -- Need OR.1 INTEGER (-1..6)..1
nomPDSCH-RS-EPRE-Offset-r10 .1 CQI-ReportPeriodic-r10 OPTIONAL --
Need ON.1 cqi-ReportPeriodicSCell-r10 ENUMERATED {setup} OPTIONAL
-- Cond PIMIRI.1 pmi-RI-Report-r9 }.1 CQI-ReportPeriodic-r10 ::=
CHOICE {.1 release NULL.1 setup SEQUENCE {.1
cqi-PUCCH-Resourceindex-r10 INTEGER (0..1184),.1 OPTIONAL -- Need
OR.1 cqi-PUCCH-ResourceindexP1-r10 INTEGER (0..1184)
cqi-pmi-ConfigIndex-r10 INTEGER (0..1123),.1
cqi-FormatIndicatorPeriodic-r10 CHOICE {.1 widebandCQI-r10 SEQUENCE
{.1 csi-ReportMode-r10 ENUMERATED {submode1, submode2} OPTIONAL --
Need OR.1 },.1 subbandCQI-r10 SEQUENCE {.1 k-r10 INTEGER (0..4),.1
periodicityFactor-r10 ENUMERATED {n2, n4}.1 }.1 },.1
ri-ConfigIndex-r10 INTEGER (0..1123) OPTIONAL, -- Need OR.1
simultaneousAckNackAndCQI-r10 BOOLEAN,.1 cqi-Mask-r9 ENUMERATED
{setup} OPTIONAL -- Need OR.1 }.1 }.1
[0357] A subframe for time domain measurement resource restriction
with respect to the ABS is configured in
RadioResourceConfigDedicated.
[0358] RadioResourceConfigDedicated is shown in Table 35 in
detail.
TABLE-US-00034 TABLE 34 RadioResourceConfigDedicated ::= SEQUENCE
{.1 srb-ToAddModList SRB-ToAddModList OPTIONAL, -- Cond HO-Conn.1
drb-ToAddModList DRB-ToAddModList OPTIONAL, -- Cond HO-Conn.1
drb-ToReleaseList DRB-ToReleaseList OPTIONAL, -- Need ON.1
mac-MainConfig CHOICE {.1 explicitValue MAC-MainConfig,.1
defaultValue NULL.1 } OPTIONAL, -- Cond HO-toEUTRA2.1 sps-Config
sps-Config OPTIONAL, -- Need ON.1 physicalConfigDedicated
physicalConfigDedicated OPTIONAL, -- Need ON.1 ...,.1 [[
rlf-TimersAndConstants-r9 RLF-TimersAndConstants-r9 OPTIONAL, --
Need ON.1 ]]..1 [[ measSubframePattern-Serv-r10CHOICE {.1 release
NULL,.1 setup MeasSubframePattern-r10.1 } OPTIONAL, -- Need ON.1
]].1 }.1
[0359] If the subframe sets C.sub.CSI,0 and C.sub.CSI,1 are
configured, a UE can assume that one of the subframe sets is
configured as a non-ABS set and the other is configured as an ABS
set.
[0360] Furthermore, if a predetermined subframe for restricted
radio link monitoring is configured, the UE can assume that
subframes other than the indicated subframe are configured as
ABSs.
[0361] The present invention provides a procedure and method
through which a UE uses a new downlink control channel when the new
downlink control channel is introduced.
[0362] In a cellular network based wireless communication system,
interference between homogeneous networks or between heterogeneous
networks is present and may affect not only data channels but also
control channels.
[0363] In LTE/LTE-A, ABSs can be assigned to a victim cell such
that the victim cell receives an interference-free signal or a
signal with weak interference or orthogonal frequency regions can
be allocated to UEs located at a cell edge using scheduling
information of BSs in order to mitigate interference of data
channels (PDSCHs).
[0364] However, control channels (e.g. PDCCH, PCFICH and PHICH)
have difficulty in avoiding interference since they can be
transmitted in all subframes and are assigned to the entire
downlink bandwidth and transmitted. Accordingly, a technique for
mitigating or avoiding interference with respect to the control
channels is needed.
[0365] FIG. 48 illustrates a method of allocating PDSCHs to cell
edge UEs in orthogonal frequency regions to mitigate interference
according to the present invention, which can be used when eNBs
exchange scheduling information.
[0366] FIG. 49 illustrates influence of interference in different
UL/DL configurations according to the present invention.
[0367] Referring to FIG. 48, since a PDCCH is transmitted using the
entire DL bandwidth, expected interference cannot be mitigated.
[0368] In addition, new interference may be generated when BSs have
different UL/DL configurations. Referring to FIG. 49, a PUCCH or a
PUSCH transmitted by UE1 may act as interference on a PDCCH and
PDSCH that need to be received by UE2.
[0369] Here, if scheduling information is exchanged between the
eNBs, the interference acting on the PDSCH can be avoided by
allocating the UEs to orthogonal frequency regions.
[0370] However, the PDCCH transmitted using the entire DL bandwidth
is affected by the PUCCH or PUSCH transmitted from UE1.
[0371] Accordingly, in order to reduce the influence of the
interference, introduction of an advanced or enhanced PDCCH
(ePDCCH) distinguished from the PDCCH is discussed.
[0372] The ePDCCH may be used not only to mitigate interference but
also to introduce new technology.
[0373] For example, the ePDCCH can be introduced to effectively
support CoMP (coordinated multipoint transmission).
[0374] The present invention relates to a communication procedure
of a UE with respect to the ePDCCH when the ePDCCH is
introduced.
[0375] The ePDCCH can be configured such that the ePDCCH and the
existing PDCCH region do not overlap.
[0376] FIGS. 50 to 57 illustrate subframes configured such that
ePDCCHs and the existing PDCCH region do not overlap.
[0377] The ePDCCHs may be configured after OFDM symbols
constituting the PDCCH.
[0378] Here, OFDM symbols constituting the PDCCH and OFDM symbols
constituting the ePDCCHs may be consecutively configured or the
number of starting OFDM symbols of the ePDCCHs may be indicated
through additional signaling (according to RRC or PDCCH)
irrespective of the order of OFDM symbols.
[0379] In this case, one or more OFDMA symbols may be present
between the PDCCH region and ePDCCH region in the time domain.
[0380] While the PDCCH region and ePDCCH region are consecutively
present in the following description, the present invention is not
limited thereto.
[0381] FIG. 50 illustrates the ePDCCH in the time domain according
to the present invention.
[0382] Referring to FIG. 50, as many preceding OFDM symbols as the
number indicated by a PCFICH in a subframe can be used as a
PDCCH.
[0383] As many consecutive OFDM symbols as the number indicated by
RRC or PDCCH can be used as an ePDCCH.
[0384] FIG. 51 illustrates a configuration of ePDCCHs occupying a
subframe according to the present invention.
[0385] Referring to FIG. 51, as many preceding OFDM symbols as the
number indicated by a PCFICH in the subframe can be used as a
PDCCH.
[0386] The remaining OFDM symbols in the subframe can be used as
ePDCCHs.
[0387] Here, frequency regions of the ePDCCH may be indicated by
RRC or PDCCH.
[0388] FIG. 52 illustrates an ePDCCH configuration in TDM within a
subframe.
[0389] Referring to FIG. 52, as many preceding OFDM symbols as the
number indicated by a PCFICH in the subframe can be used as a
PDCCH.
[0390] The remaining OFDM symbols in the subframe can be used as
ePDCCHs.
[0391] In addition, ePDCCHs for respective UEs may be
time-division-multiplexed as shown in FIG. 52. Here, frequency
regions of the ePDCCHs can be indicated by RRC or PDCCH.
[0392] FIG. 53 illustrates an ePDCCH configuration in the first
slot of a subframe according to the present invention.
[0393] Referring to FIG. 53, as many preceding OFDM symbols as the
number indicated by a PCFICH in the subframe can be used as a
PDCCH.
[0394] The remaining OFDM symbols in the first slot of the subframe
can be used as ePDCCHs. Here, frequency regions of the ePDCCHs can
be indicated by RRC or PDCCH.
[0395] FIG. 54 illustrates an ePDCCH configuration in TDM within
the first slot of a subframe according to the present
invention.
[0396] Referring to FIG. 54, as many preceding OFDM symbols as the
number indicated by a PCFICH in the subframe can be used as a
PDCCH.
[0397] The remaining OFDM symbols in the first slot of the subframe
can be used as ePDCCHs.
[0398] In addition, ePDCCHs for respective UEs may be
time-division-multiplexed as shown in FIG. 54.
[0399] Here, frequency regions of the ePDCCHs can be indicated by
RRC or PDCCH.
[0400] According to an embodiment of the present invention, various
methods can be used to signal the time or frequency region of the
ePDCCH to a UE.
[0401] The methods for signaling the time or frequency region of
the ePDCCH to the UE will now be described. However, the following
description is exemplary and the present invention is not limited
thereto.
[0402] The UE can be informed of the time or frequency region of
the ePDCCH through RRC signaling (or configuration).
[0403] The UE can be informed of the time or frequency region of
the ePDCCH using a specific format or specific field of a
predetermined PDCCH through RRC signaling (or configuration).
[0404] When an eNB indicates the frequency region of the ePDCCH,
the following methods can be used.
[0405] Indices of PRBs (or VRBs) corresponding to the ePDCCH from
among all PRBs (or VRBs) can be indicated.
[0406] The lowest PRB (or VRB) index used for the ePDCCH from among
all PRB (or VRB) indices can be indicated. Here, the UE can be
aware of positions of PRBs (or VRBs) used for the ePDCCH according
to a predetermined rule (e.g. consecutive VRBs, etc.). Otherwise,
the eNB may indicate information about the number of PRBs (or VRBs)
to be used.
[0407] Alternatively, PRBs (or VRBs) used for the ePDCCH are
indicated through a bitmap of all PRBs (or VRBs). For example, bits
of the PRBs (or VRBs) can be used in such a manner that each bit
indicates whether or not each PRB (or VRB) is used for the ePDCCH
as 0 (indicating that the corresponding PRB is not used for the
ePDCCH or 1 (indicating that the corresponding PRB is used for the
ePDCCH).
[0408] Mapping of a sequence to resource elements depends on frame
structure.
[0409] The UE cannot assume that the primary synchronization signal
is transmitted through the same antenna port as a predetermined
downlink reference signals.
[0410] In addition, the UE cannot assume that any transmission
instance of the primary synchronization signal is transmitted
through the same antenna port or ports, or used for any other
transmission instance of the primary synchronization signal.
[0411] Sequence d(n) can be mapped to resource elements according
to Equation 5.
a k , l = d ( n ) , n = 0 , , 61 k = n - 31 + N RB DL N sc RB 2 [
Equation 5 ] ##EQU00003##
[0412] For frame structure type 1, the primary synchronization
signal needs to be mapped to the last OFDM symbol in slots 0 and
10.
[0413] For frame structure type 2, the primary synchronization
signal needs to be mapped to the third OFDM symbol in slots 1 and
6.
[0414] Resource elements (k,l) in OFDM symbols used for
transmission of the primary synchronization signal can be
determined according to Equation 6. The resource elements are
reserved and not used for transmission of the primary
synchronization signal.
k = n - 31 + N RB DL N sc RB 2 n = - 5 , - 4 , , - 1 , 62 , 63 , 66
[ Equation 6 ] ##EQU00004##
[0415] In a subframe for frame structure type 1 and in a half-frame
for frame structure type 2, the same antenna port as for the
primary synchronization signal cannot be used for the secondary
synchronization signal.
[0416] The sequence d(n) can be mapped to resource elements
according to Equation 7.
a k , l = d ( n ) , n = 0 , , 61 k = n - 31 + N RB DL N sc RB 2 l =
{ N symb DL - 2 in slots 0 and 10 for frame structure type 1 N symb
DL - 1 in slots 1 and 11 for frame structure type 2 [ Equation 7 ]
##EQU00005##
[0417] The resource elements are determined according to Equation
8. The resource elements are reserved and not used for transmission
of the secondary synchronization signal.
k = n - 31 + N RB DL N sc RB 2 l = { N symb DL - 2 in slots 0 and
10 for frame structure type 1 N symb DL - 1 in slots 1 and 11 for
frame structure type 2 n = - 5 , - 4 , , - 1 , 62 , 63 , 66 [
Equation 8 ] ##EQU00006##
[0418] The block of complex-valued symbols y.sup.(p)(0), . . . ,
y.sup.(p)(M.sub.symb-1) for each antenna port is transmitted
through 4 consecutive radio frames starting in each radio frame
satisfying n.sub.f mod 4=0 and mapped in a sequence starting with
y(0) corresponding to resource elements.
[0419] Mapping to resource elements which are not reserved for
transmission of reference signals increases in order of index k,
then the index in slot 1 in subframe 0 and finally the radio frame
number. The resource-element indices are determined according to
Equation 9.
k = N RB DL N sc RB 2 - 36 + k ' , k ' = 0 , 1 , , 71 l = 0 , 1 , ,
3 [ Equation 9 ] ##EQU00007##
[0420] Here, resource elements reserved for reference signals need
to be excluded.
[0421] The mapping operation needs to assume cell-specific
reference signals for antenna ports 0-3 being present irrespective
of the actual configuration.
[0422] Furthermore, though the UE needs to assume the resource
elements reserved for reference signals in the mapping operation,
resources that are not used for transmission of reference signals
are not available for PDSCH transmission.
[0423] The UE may not make any other assumptions about the resource
elements.
[0424] FIGS. 55 and 56 illustrate temporal positions of a PSS, SSS
and PBCH in frame structure type 1 according to the present
invention.
[0425] FIG. 57 illustrates temporal positions of a PSS and SSS in
frame structure type 2 according to the present invention.
[0426] A PDCCH of LTE release 8/9 uses only as many preceding OFDMA
symbols as the number indicated by a PCFICH in a subframe.
[0427] Here, transmission of a specific control signal, such as a
synchronization signal (SS) or PBCH, does not collide with the
position of a preceding PDCCH in the subframe.
[0428] As described above, the SS is transmitted only through
symbols #5 and #6 (in the case of normal CP) or symbols #4 and #5
(in the case of extended CP) of slot 0 of a specific FDD subframe.
In TDD, the SS is transmitted through the last symbol of a specific
subframe and the third symbol of a special subframe. The PBCH is
transmitted only through OFDMA symbols #0 to #3 of slot 1 of
subframe #0.
[0429] However, if PDSCH transmission and special subframe
transmission overlap in the frequency domain, the UE assumes that
PDSCH transmission is not performed.
[0430] The UE may not be expected to receive PDSCH resource blocks
transmitted through antenna port 5, 7, or 8 in two PRBs to which a
pair of VRBs is mapped if either one of the two PRBs overlaps in
frequency with transmission of a PBCH or primary or secondary
synchronization signal in the same subframe.
[0431] The UE may monitor PDCCHs in the corresponding subframe in
order to receive a PDCCH indicating SPS activation or release, DCI
format 3/3A in a PDCCH for power control, etc. even though PDSCH
transmission in the corresponding time/frequency region is not
expected.
[0432] The ePDCCH is present after a PDCCH in the time domain (when
the ePDCCH occupies the entire region (other than the PDCCH) of a
slot or subframe, particularly) and may collide with transmission
of a special control signal such as the SS or PBCH in the frequency
region within the subframe.
[0433] In this case, the UE is not expected to receive the ePDCCH
in the frequency region within the subframe in order to reduce the
number of unnecessary ePDCCH blind decoding operations or prevent
misdetection of information.
[0434] That is, the UE is not expected to receive ePDCCH resources
in two RPBs to which a pair of VRBs is mapped if either one of the
two PRBs overlaps in frequency with transmission of either PBCH or
a primary or secondary synchronization signal in the same
subframe.
[0435] Through this UE operation, the eNB can easily signal the
time and/or frequency regions corresponding to the ePDCCH to the UE
irrespective of presence or absence of a special control signal and
the UE can reduce the number of unnecessary blind decoding
operations.
[0436] As described above, the UE may not be expected to receive
the ePDCCH in a subframe set to an ABS in order to reduce the
number of unnecessary blind decoding attempts of the UE and prevent
misdetection of information.
[0437] Embodiments of the present invention will now be
described.
[0438] First, a case in which subframe set C.sub.CSI,0 is used as
an ABS is described.
[0439] A UE can be configured with resource-restricted CSI
measurements if subframe sets C.sub.CSI,0 and C.sub.CSI,1 are
configured by higher layers.
[0440] Within subframe set C.sub.CSI,0, the UE is not expected to
receive ePDCCH resource blocks associated with a subframe that
overlaps with transmission of either PBCH or a primary or secondary
synchronization signal in the same subframe.
[0441] That is, when subframe set C.sub.CSI,0 is used as an ABS,
the UE is not expected to receive an ePDCCH in subframe set
C.sub.CSI,0.
[0442] A case in which subframe set C.sub.CSI,1 is used as an ABS
will now be described.
[0443] The UE can be configured with resource-restricted CSI
measurements if subframe sets C.sub.CSI,0 and C.sub.CSI,1 are
configured by higher layers.
[0444] Within subframe set C.sub.CSI,1, the UE is not expected to
receive ePDCCH resource blocks associated with a subframe that
overlaps with transmission of either PBCH or a primary or secondary
synchronization signal in the same subframe.
[0445] That is, when subframe set C.sub.CSI,1 is used as an ABS,
the UE is not expected to receive an ePDCCH in subframe set
C.sub.CSI,1.
[0446] A case in which subframe set C.sub.CSI,0 or C.sub.CSI,1 is
used as an ABS will now be described.
[0447] The UE can be configured with resource-restricted CSI
measurements if subframe sets C.sub.CSI,0 and C.sub.CSI,1 are
configured by higher layers.
[0448] Within subframe set C.sub.CSI,1, the UE is not expected to
receive ePDCCH resource blocks associated with a subframe that
overlaps with transmission of either PBCH or primary or secondary
synchronization signal in the same subframe.
[0449] The UE can be configured with resource-restricted CSI
measurements if subframe sets C.sub.CSI,0 and C.sub.CSI,1 are
configured by higher layers.
[0450] If a PDCCH is detected in a subframe set between C.sub.CSI,0
and C.sub.CSI,1, the UE can recognize that one subframe set is for
non-ABSs and the other subframe set is for ABSs.
[0451] Within an ABS subframe set, the UE is not expected to
receive ePDCCH resource blocks associated with a subframe that
overlaps with transmission of either PBCH or primary or secondary
synchronization signal in the same subframe.
[0452] That is, the UE can assume that the subframe set C.sub.CSI,0
or C.sub.CSI,1 in which the PDCCH is detected is a subframe set for
non-ABSs and the other subframe set is a subframe for ABSs.
[0453] The UE is not expected to receive ePDCCHs in subframes
corresponding to an ABS set.
[0454] If higher-layer signaling indicates predetermined subframes
for restricted radio link monitoring, the UE is not expected to
receive ePDCCH resource blocks associated with a subframe that
overlaps with transmission of either PBCH or primary or secondary
synchronization signal in the same subframe.
[0455] That is, when subframes for restricted radio link monitoring
are signaled and/or configured, the UE is not expected to receive
an ePDCCH when the SS or PBCH is transmitted in subframes other
than the subframes.
[0456] The ABS is supported by LTE-A release-10 UEs and UEs
following the same. Accordingly, LTE-A release-10 UEs supporting
the ABS may not be expected to receive a PDCCH in subframes set to
the ABS.
[0457] A case in which subframe set C.sub.CSI,0 is used as an ABS
will now be described.
[0458] The UE can be configured with resource-restricted CSI
measurements if subframe sets C.sub.CSI,0 and C.sub.CSI,1 are
configured by higher layers.
[0459] Within subframe set C.sub.CSI,0, the UE is not expected to
receive PDCCH resource blocks associated with a subframe that
overlaps with transmission of either PBCH or a primary or secondary
synchronization signal in the same subframe.
[0460] That is, when subframe set C.sub.CSI,0 is used as an ABS,
the UE is not expected to receive a PDCCH in subframe set
C.sub.CSI,0.
[0461] A case in which subframe set C.sub.CSI,1 is used as an ABS
will now be described.
[0462] The UE can be configured with resource-restricted CSI
measurements if subframe sets C.sub.CSI,0 and C.sub.CSI,1 are
configured by higher layers.
[0463] Within subframe sets C.sub.CSI,1, the UE is not expected to
receive PDCCH resource blocks associated with a subframe that
overlaps with transmission of either PBCH or a primary or secondary
synchronization signal in the same subframe.
[0464] That is, when subframe set C.sub.CSI,1 is used as an ABS,
the UE is not expected to receive a PDCCH in subframe set
C.sub.CSI,0.
[0465] When higher layer signaling is for predetermined restricted
radio link monitoring, the UE is not expected to receive PDCCH
resource blocks associated with a subframe that overlaps with
transmission of either PBCH or a primary or secondary
synchronization signal in the same subframe.
[0466] That is, when subframes for restricted radio link monitoring
are signaled and/or configured, the UE is not expected to receive a
PDCCH when the SS or PBCH is transmitted in subframes other than
the subframes.
[0467] The above-described embodiments of the present invention may
be applied to both the ePDCCH and PDCCH such that the UE is not
expected to receive the ePDCCH and PDCCH.
[0468] In addition, the ABS is only supported by UEs that support
LTE-A release 10 and up, and thus the above-described configuration
may be set such that the legacy LTE release-8/9 UE procedure is not
changed.
[0469] The UE may not be expected to receive an ePDCCH in subframes
set for paging in order to reduce the number of unnecessary blind
decoding attempts of the UE and prevent misdetection of information
as described above.
[0470] Specifically, the UE can be configured with
resource-restricted CSI measurements if subframe sets C.sub.CSI,0
and C.sub.CSI,1 are configured by higher layers.
[0471] Within subframe set C.sub.CSI,1, the UE is not expected to
receive PDCCH resource blocks associated with a subframe that
overlaps with transmission of either PBCH or a primary or secondary
synchronization signal in the same subframe.
[0472] That is, when C.sub.CSI,1 is used as an ABS, the UE is not
expected to receive an ePDCCH in subframe set C.sub.CSI,1.
[0473] That is, the UE is not expected to receive an ePDCCH in a
paging subframe.
[0474] Methods of configuring, allocating and indicating a paging
subframe can be implemented as follows.
[0475] The purpose of a paging procedure is to transmit paging
information to a UE in RRC_IDLE mode, to inform UEs in RRC_IDLE
state and UEs in RRC_CONNECTED state about system information
variation, to transmit an ETWS primary notification and/or ETWS
secondary notification and/or to transmit inform about a CMAS
notification.
[0476] The UE may use discontinuous reception (DRX) in the idle
mode in order to reduce power consumption.
[0477] One paging occasion (PO) is a subframe where there may be
P-RNTI transmitted on PDCCH addressing the paging message.
[0478] One paging frame (PF) is one radio frame, which may contain
one or multiple paging occasions.
[0479] When DRX is used, the UE needs to monitor one PO per DRX
cycle.
[0480] PF and PO are determined by the following equation using DRX
parameters provided through system information.
[0481] PF is determined by Equation 10.
SFN mod T=(T div N)*(UE_ID mod N) [Equation 10]
[0482] Index i_s pointing to PO from a subframe pattern can be
determined by Equation 11.
i.sub.--s=floor(UE_ID/N)mod Ns [Equation 11]
[0483] System Information DRX parameters stored in the UE can be
updated locally in the UE whenever DRX parameter values are changed
in the system information.
[0484] If the UE has no IMSI, the UE can use as default identity
UE_ID=0 and i_s as represented by Equations 10 and 11.
[0485] The following parameters can be used for calculation of the
PF and i_s.
[0486] T denotes DRX cycle of the UE. T can be determined by the
shortest of the UE specific DRX values and, if allocated by upper
layers, a default DRX value may broadcast through the system
information.
[0487] In addition, nB may be 4T, 2T, T, T/2, T/4, T/8, T/16,
T/32
[0488] N may be min(T,nB)
[0489] Ns may be max(1,nB/T)
[0490] UE_ID may be IMSI mod 1024.
[0491] Here, IMSI is given as a sequence of digits of type Integer
(0.9).
[0492] For example, IMSI can be represented as Equation 12.
IMSI=12(digit1=1,digit2=2) [Equation 12]
[0493] Table 35 shows subframe patterns in FDD in association with
the paging procedure.
TABLE-US-00035 TABLE 35 PO when PO when PO when PO when Ns i_s = 0
i_s = 1 i_s = 2 i_s = 3 1 9 N/A N/A N/A 2 4 9 N/A N/A 4 0 4 5 9
[0494] Table 36 shows TDD subframe patterns in all UL/DL
configurations in association with the paging procedure.
TABLE-US-00036 TABLE 36 PO when PO when PO when PO when Ns i_s = 0
i_s = 1 i_s = 2 i_s = 3 1 0 N/A N/A N/A 2 0 5 N/A N/A 4 0 1 5 6
[0495] In applications of the present invention, UEs supporting
LTE-A release 10 or more can be replaced by UEs supporting carrier
aggregation.
[0496] The embodiments of the present invention described
hereinbelow are combinations of elements and features of the
present invention. The elements or features may be considered
selective unless otherwise mentioned. Each element or feature may
be practiced without being combined with other elements or
features. Further, an embodiment of the present invention may be
constructed by combining parts of the elements and/or features.
Operation orders described in embodiments of the present invention
may be rearranged. Some constructions of any one embodiment may be
included in another embodiment and may be replaced with
corresponding constructions of another embodiment. It will be
obvious to those skilled in the art that claims that are not
explicitly cited in each other in the appended claims may be
presented in combination as an embodiment of the present invention
or included as a new claim by subsequent amendment after the
application is filed.
[0497] In the embodiments of the present invention, a description
is made, centering on a data transmission and reception
relationship between a base station (BS) and a User Equipment (UE).
The BS is a terminal node of a network, which communicates directly
with a UE. In some cases, a specific operation described as
performed by the BS may be performed by an upper node of the BS.
Namely, it is apparent that, in a network comprised of a plurality
of network nodes including a BS, various operations performed for
communication with a UE may be performed by the BS, or network
nodes other than the BS. The term `BS` may be replaced with the
term `fixed station`, `Node B`, `evolved Node B (eNode B or eNB)`,
`access point (AP)`, etc. The term `UE` may be replaced with the
term `terminal`, `mobile station (MS)`, `mobile subscriber station
(MSS)`, etc.
[0498] The embodiments of the present invention may be achieved by
various means, for example, hardware, firmware, software, or a
combination thereof. In a hardware configuration, the methods
according to the embodiments of the present invention may be
achieved 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.
[0499] In a firmware or software configuration, the embodiments of
the present invention may be implemented in the form of a module, a
procedure, a function, etc. For example, software code may be
stored in a memory unit and executed by a processor. The memory
unit is located at the interior or exterior of the processor and
may transmit and receive data to and from the processor via various
known means.
[0500] Those skilled in the art will appreciate that the present
invention may be carried out in other specific ways than those set
forth herein without departing from the spirit and essential
characteristics of the present invention. The above embodiments are
therefore to be construed in all aspects as illustrative and not
restrictive. The scope of the invention should be determined by the
appended claims and their legal equivalents, not by the above
description, and all changes coming within the meaning and
equivalency range of the appended claims are intended to be
embraced therein.
INDUSTRIAL APPLICABILITY
[0501] While the method and device for transmitting information in
a wireless communication system according to the present invention
are applied to 3GPP LTE in the above description, the present
invention is applicable to various wireless communication systems
in addition to the 3GPP LTE system.
* * * * *