(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2012/0269153 A1
`Seo et al.
`(43) Pub. Date:
`Oct. 25, 2012
`
`US 20120269153A1
`
`(54) METHOD AND APPARATUS FOR
`REPORTING A CHANNEL QUALITY IN A
`WIRELESS COMMUNICATION SYSTEM
`Inventors:
`Dong Youn Seo, Anyang-si (KR);
`Min Gyu Kim, Anyang-si (KR);
`Suck Che1Yang, Anyang-Si (KR);
`Joon Kui Ahn, Anyang-si (KR)
`
`(76)
`
`Publication Classification
`
`(51)
`
`Int Cl
`H04W 24/10
`H04W 72/04
`
`(2009.01)
`(200901)
`
`(52) U.s. Cl. ...................................................... .. 370/329
`
`(21) App1.No.:
`
`13/516,950
`
`(57)
`
`ABSTRACT
`
`(22) PCT Fi1ed3
`
`De“ 162 2010
`
`PCT/KR2010/009002
`
`(86) PCT No‘:
`§ 371 (OX1)
`’
`(2), (4) Date:
`
`Jun‘ 18, 2012
`.
`.
`Related U'S' Apphcatlon Data
`(60) Provisional application No. 61/287,168, filed on Dec.
`16, 2009,
`
`The present invention provided a method and apparatus for
`reporting a charmel quality in a wireless communication sys-
`tern. A terminal receives an uplink grant from a base station
`via one of a plurality ofdownlink component carriers (CCs).
`Th
`1'nk
`'
`1 d
`h
`1
`1'
`' d'
`C 1
`e up 1
`grant 1I1C u es a c ar1ne qua ity in 1cator( Q )
`request for instructing uplink allocation and CQI reporting.
`The terminal reports the CQI ofthe downlink CC being linked
`to the base station. The downlink CC being linked is one ofthe
`plurality Of d0Whlihl< CCS, Which is lihked t0 the 11Plihl< CC
`for which the uplink allocation is scheduled.
`
`One radio frame
`
` One subframe
`
`
`
`One OFDM
`
`symbol
`
`
`
`Control region
`
`Data region
`
`frequency
`
`time
`
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`

`
`Patent Application Publication
`
`Oct. 25, 2012 Sheet 1 of 8
`
`US 2012/0269153 A1
`
`FIG. 1
`
`One radio frame
`
`
`
`One subframe
`
`
`
`-‘\_~x
`
`\~~_—__-~_
`
`\-_~\~—. _~__
`
`\~_
`
`‘—\~s
`
`
`
`One OFDM
`
`symbol
`
`
`
`Control region
`
`Data region
`
`frequency
`
`time
`
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`

`
`Patent Application Publication
`
`Oct. 25, 2012 Sheet 2 of 8
`
`US 2012/0269153 A1
`
`
`
` 202
`
`FIG.2
`
`201
`
`CQI
`
`reques
`
`DLsubframe
`
`ULsubframe
`
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`

`
`Patent Application Publication
`
`Oct. 25, 2012 Sheet 3 of 8
`
`US 2012/0269153 A1
`
`FIG. 3
`
`DL CC #0
`
`DL CC #1
`
`DL CC #2
`
`
`
`L
`
`I
`
`UL CC #0
`
`UL CC #1
`
`UL CC #2
`
`Control
`
`region
`
`DL
`
`subfra me
`
`Data
`
`region
`
`UL
`
`subframe
`
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`
`Patent Application Publication
`
`Oct. 25, 2012 Sheet 4 of 8
`
`US 2012/0269153 A1
`
`FIG. 4
`
`
`
`Available CC
`
`Assigned CC
`
`
`Reference CC
`
`KCVCJ
`
`Active CC
`
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`Patent Application Publication
`
`Oct. 25, 2012 Sheet 5 of 8
`
`US 2012/0269153 A1
`
`FIG. 5
`
`701
`
`DL CC #0
`
`DL CC #1
`
`DL CC #2
`
`region I ,4 ‘K
`
`1
`
`UL CC #0
`
`UL CC #1
`
`UL
`
`!
`
`3:323:33
`
`r'v'v'v'v'''''9999’c9¢9a949a
`
`723
`
`UL
`
`subframe
`
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`Patent Application Publication
`
`Oct. 25, 2012 Sheet 6 of 8
`
`US 2012/0269153 A1
`
`DLCC#4
`
`812
`
`ULCC#4
`
`FIG.6
`
`
`
`801DLCC#1
`DLCC#0
`
`ULCC#1
`
`(N
`C)
`00
`
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`Patent Application Publication
`
`Oct. 25, 2012 Sheet 7 of 8
`
`US 2012/0269153 A1
`
`FIG. 7
`
`First CC linkage
`
`Second CC linkage
`
`S910
`
`S920
`
`
`
`
`Determination
`
`of DL CC
`
`CQI request
`
`S930
`
`CQI report
`
`5950
`
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`Patent Application Publication
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`Oct. 25, 2012 Sheet 8 of 8
`
`US 2012/0269153 A1
`
`FIG. 8
`
`50
`
`60
`
`
`
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`US 2012/0269153 A1
`
`Oct. 25, 2012
`
`METHOD AND APPARATUS FOR
`REPORTING A CHANNEL QUALITY IN A
`WIRELESS COMMUNICATION SYSTEM
`
`TECHNICAL FIELD
`
`[0001] The present invention relates to wireless communi-
`cations, and more particularly, to a method and apparatus for
`reporting channel quality in a wireless communication sys-
`tem.
`
`BACKGROUND ART
`
`In order to increase efficiency of a wireless commu-
`[0002]
`nication system, it is essential to know charmel quality. Qual-
`ity ofa downlink charmel is reported by a base station to a user
`equipment. An indicator for indicating the channel quality is
`called a channel quality indicator (CQI) or a charmel state
`indicator (CSI).
`[0003] The CQI may be a value obtained by quantizing a
`channel state (e.g., a signal to interference-plus-noise ratio
`(SINR), a carrier to interference and noise ratio (CINR), a bit
`error rate (BER), and a frame error rate (FER)) or a modula-
`tion and coding scheme (MCS) index in an MCS table. In
`addition, the CQI may include a rank indicator (RI) and/or a
`precoding matrix indicator (PMI) in a multi-antenna system.
`[0004] Long term evolution (LTE) based on 3"’ generation
`partnership project
`(3GPP)
`technical specification (TS)
`release 8 is a promising next-generation mobile communica-
`tion standard.
`
`In a typical wireless communication system, one
`[0005]
`component carrier is considered in general even if a band-
`width is differently set between an uplink and a downlink. In
`3"’ 3GPP LTE, one carrier constitutes each of the uplink and
`the downlink on the basis of a single carrier, and the band-
`width of the uplink is symmetrical to the bandwidth of the
`downlink in general.
`[0006] However, except for some areas of the world, it is
`difficult to allocate frequencies of wide bandwidths. There-
`fore, as a technique for effectively using fragmented small
`bands, a spectrum aggregation technique is being developed
`to obtain the same effect as when a band of a logically wide
`bandwidth is used by physically aggregating a plurality of
`bands in a frequency domain.
`[0007] The spectrum aggregation includes a technique for
`supporting a system bandwidth of 100 mega Hertz (MHZ) by
`using multiple carriers even if, for example, the 3GPP LIE
`supports a bandwidth of up to 20 MHZ, and a technique for
`allocating an asymmetric bandwidth between the uplink and
`the downlink.
`
`[0008] The 3GPP LTE is designed to report charmel quality
`on the basis of a single-component carrier. However, with the
`introduction of multiple carriers, there is a need for a method
`capable ofreporting charmel quality in a multi-carrier system.
`
`SUMMARY OF INVENTION
`
`Technical Problem
`
`[0009] The present invention provides a method and appa-
`ratus for reporting charmel quality in a wireless communica-
`tion system.
`
`Technical Solution
`
`In an aspect, a method for reporting charmel quality
`[0010]
`in a wireless communication system includes receiving an
`
`uplink grant from a base station through one of a plurality of
`downlink component carriers (CCs), the uplink grant includ-
`ing an uplink allocation and a channel quality indicator (CQI)
`indicating a triggering of CQI reporting, and reporting a CQI
`of a linked downlink CC to the base station. The linked
`
`downlink CC is a downlink CC linked to an uplink CC in
`which the uplink allocation is scheduled among the plurality
`of downlink CCs.
`
`[0011] The uplink grant may further include a carrier indi-
`cator field (CIF) indicating the uplink CC in which the uplink
`allocation is scheduled.
`
`[0012] The method may further include receiving system
`information including a first CC linkage between at least one
`uplink CC and the plurality of downlink CCs from the base
`station. The uplink CC in which the uplink allocation is
`scheduled may be determined according to the first CC link-
`age.
`
`[0013] The method may further include receiving a radio
`resource control (RRC) message including a second CC link-
`age between at least one uplink CC and the plurality of down-
`link CCs from the base station. The uplink CC in which the
`uplink allocation is scheduled may be determined according
`to the second CC linkage.
`[0014]
`In another aspect, an apparatus configured for
`reporting charmel quality in a wireless communication sys-
`tem is provided. The apparatus includes a radio frequency
`(RF) unit configured for transmitting and receiving a radio
`signal, and a processor coupled to the RF unit and configured
`for receiving an uplink grant from a base station through one
`of a plurality of downlink component carriers (CCs), the
`uplink grant including an uplink allocation and a channel
`quality indicator (CQI) indicating a triggering of CQI report-
`ing, and reporting a CQI of a linked downlink CC to the base
`station. The linked downlink CC is a downlink CC linked to
`
`an uplink Cc in which the uplink allocation is scheduled
`among the plurality of downlink CCs.
`
`Advantageous Effects
`
`[0015] The present invention provides a method for trans-
`mitting a control signal in a multi-carrier system capable of
`cross carrier scheduling. More specifically, a method and
`apparatus for reporting charmel quality are proposed.
`
`DESCRIPTION OF DRAWINGS
`
`FIG. 1 shows a downlink radio frame structure in 3"’
`[0016]
`generation partnership project (3GPP) long term evolution
`(LTE).
`FIG. 2 shows channel quality indicator
`[0017]
`reporting in the conventional 3GPP LTE.
`[0018]
`FIG. 3 shows an example of multiple carriers
`[0019]
`FIG. 4 shows an example of a multi-carrier opera-
`tion.
`
`(CQI)
`
`[0020]
`1ng.
`
`FIG. 5 shows an example of cross-carrier schedul-
`
`FIG. 6 is a diagram for describing an operation
`[0021]
`according to an embodiment of the present invention.
`[0022]
`FIG. 7 is a flowchart showing a CQI reporting
`method according to an embodiment ofthe present invention.
`
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`
`US 2012/0269153 A1
`
`Oct. 25, 2012
`
`FIG. 8 is a block diagram showing a wireless com-
`[0023]
`munication system according to an embodiment of the
`present invention.
`
`MODE FOR INVENTION
`
`[0024] A user equipment (UE) may be fixed or mobile, and
`may be referred to as another terminology, such as a mobile
`station (MS), a mobile terminal (MT), a user terminal (UT), a
`subscriber station (SS), a wireless device, a personal digital
`assistant (PDA), a wireless modem, a handheld device, etc.
`[0025] A base station (BS) is generally a fixed station that
`communicates with the UE and may be referred to as another
`terminology, such as an evolved node-B (eNB), a base trans-
`ceiver system (BTS), an access point, etc.
`[0026] Each BS provides a communication service to a
`specific geographical region (generally referred to as a cell).
`The cell can be divided into a plurality of regions (referred to
`as sectors).
`[0027]
`FIG. 1 shows a downlink radio frame structure in 3"’
`generation partnership project (3GPP) long term evolution
`(LTE). The section 6 of 3GPP TS 36.211 V8.7.0 (2009-05)
`“Evolved Universal Terrestrial Radio Access (E-UTRA);
`Physical Charmels and Modulation (Release 8)” may be
`incorporated herein by reference.
`[0028] A radio frame consists of20 subframes indexed with
`0 to 19. One subframe consists of 2 slots. A time required for
`transmitting one subframe is defined as a transmission time
`interval (TTI). For example, one subframe may have a length
`of 1 millisecond (ms), and one slot may have a length of 0.5
`ms.
`
`[0029] One slot may include a plurality of orthogonal fre-
`quency division multiplexing (OFDM) symbols in a time
`domain. Since the 3GPP LTE uses orthogonal frequency divi-
`sion multiple access (OFDMA) in a downlink (DL), the
`OFDM symbol is only for expressing one symbol period in
`the time domain, and there is no limitation in a multiple
`access scheme or terminologies. For example, the OFDM
`symbol may also be referred to as another terminology such
`as a single carrier frequency division multiple access (SC-
`FDMA) symbol, a symbol period, etc.
`[0030] Although it is described that one slot includes 7
`OFDM symbols for example, the number of OFDM symbols
`included in one slot may vary depending on a length of a
`cyclic prefix (CP). According to 3GPP TS 36.211 V8.7.0, in
`case of a normal CP, one subframe includes 7 OFDM sym-
`bols, and in case of an extended CP, one subframe includes 6
`OFDM symbols.
`[0031] A resource block (RB) is a resource allocation unit,
`and includes a plurality of subcarriers in one slot. For
`example, if one slot includes 7 OFDM symbols in a time
`domain and the RB includes 12 subcarriers in a frequency
`domain, one RB can include 7><12 resource elements (REs).
`[0032] A DL subframe is divided into a control region and
`a data region in the time domain. The control region includes
`up to three preceding OFDM symbols of a 15’ slot in the
`subframe. The number of OFDM symbols included in the
`control region may vary. A physical downlink control channel
`(PDCCH) is allocated to the control region, and a physical
`downlink shared charmel (PDSCH) is allocated to the data
`region.
`[0033] As disclosed in 3GPP TS 36.211 V8.7.0, the 3GPP
`LTE classifies a physical channel into a data channel and a
`control channel. Examples of the data channel include a
`physical downlink shared charmel (PDSCH) and a physical
`
`uplink shared channel (PUSCH). Examples of the control
`channel include a physical downlink control charmel (PD-
`CCH), a physical control format indicator charmel (PC-
`FICH), a physical hybrid-ARQ indicator charmel (PHICH),
`and a physical uplink control charmel (PUCCH).
`[0034] The PCFICH transmitted in a 15’ OFDM symbol of
`the subframe carries a control format indicator (CFI) regard-
`ing the number of OFDM symbols (i.e., a size of the control
`region) used for transmission of control channels in the sub-
`frame. The UE first receives the CFI through the PCFICH,
`and thereafter monitors the PDCCH.
`
`[0035] The PHICH carries a positive-acknowledgement
`(ACK)/negative-acknowledgement
`(HACK)
`signal
`for
`uplink hybrid automatic repeat request (HARQ). The ACK/
`NACK signal for uplink (UL) data on the PUSCH transmitted
`by the UE is transmitted on the PHICH.
`[0036] Control
`information transmitted through the
`PDCCH is referred to as downlink control information (DCI).
`The DCI may include a resource allocation of the PDSCH
`(this is referred to as a DL grant), a resource allocation of a
`PUSCH (this is referred to as a UL grant), a set of transmit
`power control commands for individual UEs in any UE group
`and/or activation of a voice over Internet protocol (VoIP).
`[0037] The DCI on the PDCCH is received by using blind
`decoding. A plurality of candidate PDCCHs can be transmit-
`ted in the control region of one subframe. The UE monitors
`the plurality of candidate PDCCHs in every subframe.
`Herein, monitoring is an operation in which the UE attempts
`decoding ofeach PDCCH according to a format ofPDCCH to
`be monitored. The UE monitors a set of PDCCH candidates in
`
`a subframe to find its own PDCCH. For example, ifthere is no
`cyclic redundancy check (CRC) error detected by performing
`de-making on an identifier (i.e., cell-radio network temporary
`identifier (RNTI)) of the UE in a corresponding PDCCH, the
`UE detects this PDCCH as a PDCCH having its DCI.
`[0038]
`In order to receive DL data, the UE first receives a
`DL grant on the PDCCH. DL data on the PDSCH is received
`by using the DL grant. In addition, to transmit UL data, the
`UE first receives a UL grant on the PDCCH. UL data is
`transmitted on the PUSCH by using the UL grant.
`[0039] A physical broadcast channel (PBCH) is transmitted
`in first four OFDM symbols in a 2"d slot of a 1” subframe of
`a radio frame. The PBCH carries system information neces-
`sary for communication between a UE and a BS. The system
`information transmitted through the PBCH is referred to as a
`master information block (MIB). In comparison thereto, sys-
`tem information transmitted through the PDCCH is referred
`to as a system information block (SIB).
`[0040] Now, channel quality reporting in 3GPP LTE will be
`described with reference to the section 7 .2 of 3GPP TS 3 6.213
`
`V8.7.0(2009-05).
`[0041]
`FIG. 2 shows CQI reporting in the conventional
`3GPP LTE.
`
`[0042] ABS transmits a CQI request 201 through a PDCCH
`in a DL subframe. The CQI request 201 is included in a DCI
`format 0 or a random access response. The DCI format 0 is
`used for transmission of a UL grant. The UL grant further
`includes a UL resource allocation for a PUSCH.
`
`[0043] The CQI request 201 indicates whether CQI report-
`ing is triggered by using a 1-bit field. For example, if a value
`of the CQI request 201 is set to ‘1’, it means that the BS
`requests the UE to perform CQI reporting.
`
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`US 2012/0269153 A1
`
`Oct. 25, 2012
`
`Ifthe CQI request 201 indicates the triggering ofthe
`[0044]
`CQI reporting, the UE transmits a CQI 202 to the BS through
`a PUSCH.
`
`Since the UE reports the CQI at the request of the
`[0045]
`BS, this is called aperiodic CQI reporting.
`[0046]
`In 3GPP LTE, there are three types of CQI feedback,
`that is, Wideband, UE selected, and Higher layer-configured.
`In addition, there are also three types ofPMI feedback, that is,
`No PMI, Single PMI, and Multiple PMI. According to the
`CQI feedback type and the PMI feedback type, a transmission
`mode is divided as shown in Table 1 below.
`
`TABLE 1
`
`No PMI
`
`Single PMI
`
`Mode 2-0
`
`Mode 3-0
`
`Mode 3-1
`
`Multiple PMI
`Mode l-2
`
`Mode 2-2
`
`Wideband
`(wideband CQI)
`UE selected
`(subband CQI)
`Higher layer-
`configured
`(subband CQI)
`
`[0047] According to the mode 1-2, a PMI is selected under
`the assumption that data is transmitted in each subband. The
`UE determines a CQI by assuming the selected PMI with
`respect to a system band or a whole band designated by a
`higher layer (such a band is called a set S). The UE transmits
`the CQI and the PMI of each subband. Since the CQI of a
`whole band or subbands included in the set S is transmitted, it
`is called a wideband CQI. A size of each subband may vary
`depending on a size of the system band.
`[0048] According to the mode 2-0, the UE selects M (M>0)
`preferred subbands in the system band or the set S. The UE
`determines a CQI for the selected M subbands (such a sub-
`band is called a subband CQI). In addition, the UE addition-
`ally determines a wideband CQI with respect to the system
`band or the set S. The UE transmits the selected M subbands,
`one CQI for the selected M subbands, and the wideband CQI.
`[0049] According to the mode 2-2, M preferred subbands
`and a single PMI for the M preferred subbands are deter-
`mined. In addition, the UE determines a wideband CQI with
`respect to the system band or the set S. The UE transmits the
`selected M subbands, one CQI for the selected M subbands, a
`single PMI for the M selected subbands, and a wideband CQI.
`[0050] According to the mode 3-0, the UE determines the
`wideband CQI. Further, the UE determines a CQI for each
`subband.
`
`[0051] According to the mode 3-1, the UE determines a
`single PMI with respect to the system band or the set S. The
`UE determines a wideband CQI and a subband CQI for each
`subband by assuming the single PMI.
`[0052] Meanwhile, uplink power control is used in the
`wireless communication system. The BS increases uplink
`power when a channel environment
`is not good, and
`decreases the uplink transmit power when the channel envi-
`ronment is good. This is to decrease interference to a neigh-
`boring cell due to excessive transmit power and to optimize a
`power usage amount as much as possible.
`[0053]
`In 3GPP LTE, a transmit power command (TPC) is
`used for uplink transmit power control, and transmit power is
`controlled independently in each of a PUCCH and a PUSCH.
`In general, the TPC for the PUCCH used in transmission of an
`HARQ ACK/NACK signal is included in a DL grant. Further,
`the TPC for the PUSCH is included in a UL grant.
`
`[0054] Now, a multiple-carrier system will be described.
`[0055]
`To support a higher data rate, a multiple-carrier sys-
`tem supporting a plurality of component carriers (CCs) is
`taken into account.
`
`Spectrum aggregation (or bandwidth aggregation,
`[0056]
`also referred to as carrier aggregation) supports a plurality of
`CCs. The spectrum aggregation is introduced to support an
`increasing throughput, to prevent a cost increase caused by
`using a broadband radio frequency (RF) element, and to
`ensure compatibility with legacy systems. For example, if 5
`CCs are assigned as a granularity of a carrier unit having a
`bandwidth of 20 MHz, a bandwidth of up to 100 MHz can be
`supported.
`[0057]
`FIG. 3 shows an example of multiple carriers.
`Although three DL CCs and three UL CCs are shown herein,
`the number of DL CCs and the number of UL CCs are not
`
`limited thereto. A PDCCH and a PDSCH are independently
`transmitted in each DL CC. A PUCCH and a PUSCH are
`
`independently transmitted in each UL CC.
`[0058]
`FIG. 4 shows an example of a multi-carrier opera-
`tion. Even if a multi-carrier system supports a plurality of
`CCs, the number of supported CCs may differ depending on
`a cell or UE capability.
`[0059] An available CC indicates all CCs that can be used
`by the system. Herein, there are 6 CCs (i.e., CC #0 to CC #5).
`[0060] An assigned CC is a CC assigned by a BS to a UE
`according to the UE capacity among available CCs. Although
`it is shown that the CC #0 to the CC #3 are assigned CCs, the
`number of assigned CCs may be less than or equal to the
`number of available CCs.
`
`[0061] An active CC is a CC used by the UE to perform
`reception and/or transmission of a control signal and/or data
`with respect to the BS. The UE can perform PDCCH moni-
`toring and/or PDSCH buffering with respect to some or all of
`the active CCs. The active CCs can be activated or deactivated
`
`among the assigned CCs. Among the active CCs, a CC which
`is always activated is called a reference CC.
`[0062]
`In a multi-carrier system, a CC linkage can be
`defined between a DL CC and a UL CC. The CC linkage
`implies a mapping relation between a DL CC in which a
`PDCCH for carrying a UL grant is transmitted and a UL CC
`scheduled by the UL grant. Alternatively, the CC linkage may
`be a mapping relation between a DL CC (or UL CC) in which
`data for HARQ is transmitted or a UL CC (or DL CC) in
`which an HARQ ACK/NACK signal is transmitted. The CC
`linkage may be a relationship between a DL CC which is a
`target of CQI reporting and a UL CC for transmitting a CQI.
`[0063] The example of FIG. 3 shows a symmetric CC link-
`age in which a DL CC and a UL CC are one-to-one mapped.
`[0064] The CC linkage can be configured as a static CC
`linkage and a dynamic CC linkage as follows.
`[0065]
`In a first method, the CC linkage is fixed. This is
`called a fixed CC linkage or a static CC linkage. This can be
`signaled by using system information which is common
`information. Since a UL CC to be scheduled by a UL grant
`can be determined through the static CC linkage, additional
`signaling for configuring a linkage between a UL CC and a
`DL CC and transmitted for each UE is not necessary.
`[0066]
`In a second method, the CC linkage is dynamically
`or semi-statically changed or overridden. This is called the
`dynamic CC linkage. This can be reported by the BS to the UE
`by using a radio resource control (RRC) message or L1/L2
`signaling. The dynamic CC linkage can be UE-specific (in
`this case, it can be specific for each CC or may be common for
`
`TELEFONAKTIEBOLAGET LM ERIC SSON AND
`
`ERICSSON INC. EX. NO. 1008
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`ERICSSON INC. EX. NO. 1008
`
`

`
`US 2012/0269153 A1
`
`Oct. 25, 2012
`
`each CC), or can be UE group-specific or cell-specific. The
`dynamic CC linkage canbe mapped in a 1 :1 manner or 1:M or
`M21 manner
`
`[0067] Two methods are possible as CC scheduling.
`[0068]
`In a first method, a fixed CC linkage is utilized. A
`UL grant is transmitted through a DL CC. A UL transport
`block is transmitted by using the UL grant through a UL CC
`linked to the DL CC. Since a UL CC to be scheduled by the
`UL grant can be determined through a predefined CC linkage,
`additional signaling is not necessary.
`[0069]
`In a second method, a CC to be scheduled is directly
`indicated. For example, a PDCCH and a PDSCH are trans-
`mitted in different DL CCs, or a PUSCH is transmitted
`through a UL CC not linked to a DL CC in which the PDCCH
`is transmitted. This is called cross-carrier scheduling.
`[0070]
`FIG. 5 shows an example of cross-carrier schedul-
`ing. It is assumed that a DL CC #0 is linked to a UL CC #0, a
`DL CC #1 is linked to a UL CC #1, and a DL CC #2 is linked
`to a UL CC #2.
`
`[0071] A 15’ PDCCH 710 ofthe DL CC #0 carries DCI for
`a PDSCH 702 ofthe same DL CC #0. A 2”’ PDCCH 711 of
`the DL CC #0 carries DCI for a PDSCH 712 ofthe DL CC #1.
`A 3"’ PDCCH 721 ofthe DL CC #0 carries DCI for a PUSCH
`722 of the unlinked UL CC #2.
`
`For cross-carrier scheduling, the DCI ofthe PDCCH
`[0072]
`may include a carrier indicator field (CIF). The CIF indicates
`a DL CC or a UL CC scheduled through the DCI. The CIF
`may include an index of a UL CC or an index of a DL CC
`scheduled through the DCI. For example, the 2”’ PDCCH 71 1
`may include a CIF indicating the DL CC #1. The 3"’ PDCCH
`721 may include a CIF indicating the UL CC #2.
`[0073] As described above, in the conventional 3GPP LTE,
`a UL frequency band and a DL frequency band correspond to
`each other, and only one UL and one DL CC are present.
`Therefore, a TPC included in DCI for a DL grant is control
`information for a UL CC corresponding to a DL CC, and a
`CQI request included in DCI for a UL grant is control infor-
`mation for a DL CC corresponding to a scheduled UL CC.
`[0074] However, an ambiguity may occur in a multi-carrier
`system using a plurality of CCs according to the conventional
`3GPP LTE structure.
`
`[0075] More specifically, a 3"’ PDCCH 721 transmitted
`through a DL CC #0 carries a UL grant for scheduling a UL
`CC #2. Assume that the UL CC #2 is linked to a DL CC #2. In
`
`this case, when a CQI request is included in the UL grant,
`whether the CQI request is a CQI for one DL CC or a CQI for
`a DL CC group (or all CCs)or which CC(s) is a target DL CC
`thereof may be ambiguous.
`[0076]
`For example, ifthe CQI request is for one CC, it may
`be ambiguous whether the CQI request is for requesting CQI
`reporting for the DL CC #0 in which the 3"’ PDCCH 721 is
`transmitted or is for requesting CQI reporting for the DL CC
`#2 linked to the UL CC #2 in which the UL grant is scheduled.
`[0077]
`FIG. 6 is a diagram for describing an operation
`according to an embodiment of the present
`invention.
`Although there are 5 DL CCs and 5 UL CCs, the number of
`CCs is not limited thereto. It is assumed that a DL CC #k
`
`(0<:k<:4) is linked to a UL CC #k according to a static CC
`linkage. The static CC linkage can be reported by the BS to
`the UE by using a part of system information (i.e., MIB or
`SIB).
`It is assumed that a CIF consists of 3 bits, and each
`[0078]
`value is defined by Table 2 below.
`
`TABLE 2
`
`Description
`UL CC index 0
`UL CC index 1
`UL CC index 2
`UL CC index 3
`UL CC index 4
`Reserved
`Reserved
`UL CC index 0, dynamic CC linkage
`
`CIF value
`0
`1
`2
`3
`4
`5
`6
`7
`
`[0079] Hereinafter, a CC index of a CIF in a UL grant is an
`index of a UL CC scheduled by the UL grant. However, in
`another example, a CC index of a CIF in a UL grant may be an
`index of a DL CC linked to a UL CC to be scheduled by the
`UL grant.
`[0080] DCI ofa 15’ PDCCH 801 ofthe DL CC #1 includes
`a UL grant for scheduling the UL CC #0. The UL grant
`includes a UL resource allocation 802, a CQI request, and a
`CIF.
`
`If a value of the CQI request is 0, CQI reporting is
`[0081]
`not triggered, and if the value of the CQI request is 1, CQI
`reporting is triggered.
`[0082] Assume that the value of the CIF included in the UL
`grant ofthe 1” PDCCH 801 is set to 0, i.e., an index ofthe UL
`CC #0. When CQI reporting is triggered, the UE can report a
`CQI for the DL CC #0 linked to a UL CC having a CC index
`0 (i.e., UL CC #0). That is, when CQI reporting is triggered,
`the UE reports a CQI of a DL CC linked to a UL CC indicated
`by a CIF included in the UL grant.
`[0083] Assume that CQI reporting is triggered, and the CIF
`value is set to 7 which indicates the dynamic CC linkage.
`When the CIF value is 7, a UL CC in which a UL grant is
`scheduled can be predetermined. In this example, if the CIF
`value is 7, it indicates the UL CC #0. The CIF value indicating
`the dynamic CC linkage is for exemplary purposes only, and
`thus can be set to any specific value. When the CIF value
`indicates the dynamic CC linkage, a UL CC scheduled by a
`UL grant may be a UL CC defined by a higher layer message
`such as an RRC message, or may be a UL CC which is
`predetermined to transmit a control signal.
`[0084] The dynamic CC linkage indicates CC mapping for
`CQI reporting. The dynamic CC linkage can indicate at least
`any one of the following four types.
`[0085]
`(1) all available DL CCs
`[0086]
`(2) all active DL CCs
`[0087]
`(3) all assigned DL CCs
`[0088]
`(4) a DL CC group (or DL CC list) including at least
`one DL CC
`
`[0089] That is, if the dynamic CC linkage type (4) is used,
`the UE reports a CQI for DL CCs in a DL CC group.
`[0090] The dynamic CC linkage may be pre-defined, or
`may be transmitted by the BS to the UE by using a radio
`resource control (RRC) message or L1/L2 signaling. The
`dynamic CC linkage may be UE-specific, UE group-specific,
`or cell-specific. The dynamic linkage may be specific for each
`CC or common for each CC.
`
`[0091] Which type ofdynamic CC linkage will be used can
`be reported by the BS to the UE by using the RRC message.
`If the dynamic CC linkage type (4) is used, information
`regarding a DL CC group for reporting a CQI can be reported
`by the BS to the UE by using the RRC message.
`
`TELEFONAKTIEBOLAGET LM ERIC SSON AND
`
`ERICSSON INC. EX. NO. 1008
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`ERICSSON INC. EX. NO. 1008
`
`

`
`US 2012/0269153 A1
`
`Oct. 25, 2012
`
`[0092] One or more dynamic CC linkages can be used. In
`the example of Table 2, if the CIF value is 6, it may indicate
`the dynamic CC linkage type (1), and if the CIF value is 7, it
`may indicate the dynamic CC linkage type (4). Alternatively,
`it is also possible to designate a plurality of dynamic CC
`linkage types (4) each of which can be designated by using a
`CIF. For example, ifthe CIF value is 6, it indicates DL CCs #0
`and #1, and ifthe CIF value is 7, it indicates the DL CCs #2 to
`#4.
`
`[0093] DCI ofa 2"d PDCCH 811 ofa DL CC #2 includes a
`DL grant for a DL CC #3. The DL grant includes a DL
`resource allocation 812, a CIF, and a TPC. Assume that the
`CIF value is set to 3 which is an index of the DL CC #3. The
`
`TPC may be a TPC for a UL CC #3 linked to the DL CC #3.
`Alternatively, the TPC may be a TPC for the UL CC #2 linked
`to the DL CC #2 in which the 2"d PDCCH 811 is transmitted.
`
`[0094] Although it is shown in this example that the TPC is
`included in the DL grant, the TPC may be included in a UL
`grant. In this case, the TPC may be a TPC for a UL CC
`indicated by the CIF. Alternatively, the TPC may be a TPC for
`a UL CC linked to a DL CC in which the UL grant is trans-
`mitted.
`
`[0095] The proposed invention is also applicable to not
`only CQI reporting and/or TPC transmission but also other
`control signals. A CQI request is a signal used when the BS
`requests the UE to set or trigger a control signal for a corre-
`sponding DL CC (or UL CC), and can be called a control
`setup signal or a control trigger signal.
`[0096] The dynamic CC linkage is not determined by a
`specific CIF value, but can be predetermined by using an RRC
`message or the like. If the CQI request is 0, the UE may not
`transmit the CQI report, and if the CQI request is 1, the UE
`may transmit the CQI report according to a dynamic CC
`linkage determined by using the RRC message.
`[0097] Although a case where the CQI request is 1 bit is
`considered in the aforementioned example, more various
`examples may be possible if the number of bits of the CQI
`request is increased. Table 3 below shows a configuration
`depending on each value when the CQI request is 2 bits.
`
`TABLE 3
`
`Value of CQI request Description
`
`mI\J>—AO
`
`No CQI reporting
`CQI reporting based on static CC linkage
`CQI reporting based on 1‘’ dynamic CC linkage
`CQI reporting based on 2"“? dynamic CC linkage
`
`Ifthe CQI request value is 1, the UE reports the CQI
`[0098]
`according to the static CC linkage. For example, upon receiv-
`ing a UL grant for a UL CC #1, the UE reports a CQI for a DL
`CC linked to the UL CC #1. If the CQI request value is 2 or 3,
`the UE reports a CQI according to the pre-defined 1” or 2"d
`dynamic CC linkage. The 15’ and 2”’ dynamic CC linkages
`can be determined by using