(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
`
`(43) International Publication Date
`
`8 July 2010 (08.07.2010) (10) International Publication Number
`
`WO 2010/077051 A2
`
`(51)
`
`(21)
`
`(22)
`
`(25)
`
`(26)
`
`(30)
`
`(71)
`
`(72)
`(75)
`
`International Patent Classification:
`
`H04B 7/04 (2006.01)
`
`H04W28/I6 (2009.01)
`
`International Application Number:
`PCT/KR2009/007858
`
`International Filing Date:
`29 December 2009 (29.12.2009)
`
`Filing Language:
`
`Publication Language:
`
`Priority Data:
`61/141,211
`29 December 2008 (29.12.2008)
`10-2009-0128759
`
`22 December 2009 (22.12.2009)
`
`English
`
`English
`
`US
`
`KR
`
`Applicant 0’or all designated States except US): LG
`ELECTRONICS INC.
`[KIUKR]; 20, Yeouido-dong,
`Yeongdeungpo-gu, Seoul, 150-721 (KR).
`
`Inventors; and
`Inventors/Applicants 0’or US only): SEO, Dong Youn
`[KIUKR]; LG Institute, #533, Hogye 1(il)-dong, Dongan-
`gu, Anyang-si, Gyeonggi-do 431-080 (KR). LEE, Jung
`Hoon [KIUKR]; LG Institute, #533, Hogye 1(il)-dong,
`Dongan-gu, Anyang-si, Gyeonggi-do 431-080 (KR).
`AHN, Joon Kui [KIUKR]; LG Institute, #533, Hogye
`1(il)-dong, Dongan-gu, Anyang-si, Gyeonggi-do 431-080
`(KR).
`
`(74)
`
`(81)
`
`(84)
`
`Agents: KIM, Yong In et al.; KBK & Associates, 7th
`Floor, Hyundae Building, 175-9, Jamsil-dong, Songpa-ku,
`Seoul, 138-861 (KR).
`
`Designated States (unless otherwise indicated, for every
`kind of national protection available): AE, AG, AL, AM,
`AO, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ,
`CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO,
`DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT,
`HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP,
`KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, ME,
`MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO,
`NZ, OM, PE, PG, PH, PL, PT, RO, RS, RU, SC, SD, SE,
`SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, TT,
`TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW.
`
`Designated States (unless otherwise indicated, for every
`kind of regional protection available): ARIPO (BW, GH,
`GM, KE, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, ZM,
`ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ,
`TM), European (AT, BE, BG, CH, CY, CZ, DE, DK, EE,
`ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV,
`MC, MK, MT, NL, NO, PL, PT, RO, SE, SI, SK, SM,
`TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW,
`ML, MR, NE, SN, TD, TG).
`
`(54) Title: METHOD FOR TRANSMITTING CONTROL INFORMATION TO REQUEST CHANNEL QUALITY INDICA-
`TOR IN A WIRELESS COMMUNICATION SYSTEM SUPPORTING MULTIPLE TRANSMISSION BANDWIDTHS
`
`[Continued on nextpage]
`
`[Fig. 8]
`
`-PDSCI-1*
`
`
`
`——PUSCH-—
`
`CQ11'eques1 ’\‘
`Other control information field
`1
`
`f~ Indication of DL CC ofCQl
`l CC
`
`CC A
`
`CC C
`
`CC B
`
`ICCC
`
`- PDCCH for UL grant has explicit
`Indication of DL CC of CQI
`
`lll ll ll
`
`CQI of
`CC C
`
`(57) Abstract: A method for transmitting con-
`trol information to request a Channel Quality In-
`dicator (CQI) in a Wireless communication sys-
`tem supporting a plurality of transmission bands
`is disclosed. The method includes generating
`control
`information including downlink trans-
`mission band indication information and CQI re-
`quest
`information,
`the downlink transmission
`band indication information indicating a down-
`link transmission band requiring CQI reporting
`among a plurality of downlink transmission
`bands and the CQI request information request-
`ing CQI reporting for the downlink transmission
`band, and transmitting the generated control in-
`formation on a downlink control channel of a
`
`band
`transmission
`downlink
`predetermined
`among the plurality of downlink transmission
`bands.
`
`
`
`wo2010/077051A2I||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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`WO 2010/077051 A2 ||||||||||||||||||||||||||||||||||||||||||ll|||||||||||||||||||||||||||||||||||||||||||||||||||
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`Published:
`
`— without international search report and to be republished
`upon receipt oftlzat report (Rule 48.2(g))
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
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`

`
`WO 2010/077051
`
`PCT/KR2009/007858
`
`Description
`
`Title of Invention: METHOD FOR TRANSMITTING CONTROL
`
`INFORMATION TO REQUEST CHANNEL QUALITY
`
`INDICATOR IN A WIRELESS COMMUNICATION SYSTEM
`
`SUPPORTING MULTIPLE TRANSMISSION BANDWIDTHS
`
`Technical Field
`
`[1]
`
`The present invention relates to a method for transmitting control information to
`
`request a Channel Quality Indicator (CQI) in a wireless communication system
`
`[2]
`
`[3]
`
`supporting a plurality of transmission bandwidths.
`
`Background Art
`
`(1) Multiple Input Multiple Output (MIMO) Technology
`
`The term "MIMO "is short for Multiple Input Multiple Output. Beyond conventional
`
`schemes using a single Transmit (TX) antenna and a single Reception (RX) antenna,
`
`MIMO uses a plurality of TX antennas and a plurality of RX antennas to thereby
`
`increase the transmission and reception efficiency of data. With the use of multiple
`
`antennas at a transmitter or a receiver, MIMO seeks to increase capacity or improve
`
`performance in a wireless communication system. The term "MIMO" is inter-
`
`changeable with "multi—antenna".
`
`[4]
`
`The MIMO technology does not depend on a single antenna path to receive an entire
`
`message. Rather, it completes the message by combining data fragments received
`
`through a plurality of antennas. Because MIMO may increase data rate within a certain
`
`area or extend system coverage at a given data rate, it is considered as a promising
`
`future—generation mobile communication technology that may find its use in a wide
`
`range including mobile terminals, relays, etc. With the growth of data communication,
`
`MIMO is attracting attention as a future— generation technology that may overcome a
`
`limit on transmission capacity that is almost reached due to the increased data commu-
`
`[5]
`
`[6]
`
`[7]
`
`nication.
`
`(2) MIMO System Model
`
`FIG. 1 illustrates the configuration of a typical MIMO communication system.
`
`Referring to FIG. 1, a simultaneous increase in the number of TX antennas of a
`
`transmitter to NT and in the number of RX antennas of a receiver to NR increases a the-
`
`oretical channel transmission capacity in proportion to the number of antennas,
`
`compared to use of a plurality of antennas at only one of the transmitter and the
`
`receiver. Therefore, transmission rate and frequency efficiency are remarkably
`
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`
`WO 2010/077051
`
`PCT/KR2009/007858
`
`increased. Given a maximum transmission rate R, that may be achieved in case of a
`
`single antenna, the increase of channel transmission capacity may increase the
`
`transmission rate, in theory, to the product of R0 and RT in case of multiple antennas. RT
`
`is a transmission rate increase rate.
`
`[8]
`
`MathFigure 1
`
`[Math. 1]
`
`R, = min(N, , NR)
`
`[9]
`
`For instance, a MIMO communication system with four TX antennas and four RX
`
`antennas may achieve a four—fold increase in transmission rate theoretically, relative to
`
`a single—antenna system. Since the theoretical capacity increase of the MIMO system
`
`was proved in the middle 1990's, many techniques have been actively studied to
`
`increase data rate in real implementation. Some of the techniques have already been
`
`reflected in various wireless communication standards for 3“ Generation (3G) mobile
`
`communications, future—generation Wireless Local Area Network (WLAN), etc.
`
`[10]
`
`Concerning the research trend of MIMO, active studies are underway in many
`
`respects of MIMO, inclusive of studies of information theories related to calculation of
`
`multi—antenna communication capacity in diverse channel environments and multiple
`
`access environments, studies of measuring MIMO radio channels and MIMO
`
`modeling, studies of time—space signal processing techniques to increase transmission
`
`reliability and transmission rate, etc.
`
`[11]
`
`To describe a communication scheme in a MIMO system in detail, the following
`
`mathematical model may be used. It is assumed that there are NT TX antennas and NR
`
`RX antennas as illustrated in FIG. 1. Regarding a transmission signal, up to NT pieces
`
`of information can be transmitted through the NT TX antennas, as eXpressed as the
`
`following vector.
`
`[12]
`
`MathFigure 2
`
`[Math.2]
`
`S :lS1> S2: ' I '3 SA/,-JT
`
`[13]
`
`A different transmit power may be applied to each piece of transmission information
`
`s1,.s'2,---,sNT
`
`. Let the transmit power levels of the transmission information be denoted by
`
`3.1%
`
`3..-,
`
`, respectively. Then the power—controlled transmission information
`/\
`
`S m
`
`ay be given as the following Math Figure 3.
`
`[14]
`
`MathFigure 3
`
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`

`
`WO 2010/077051
`
`PCT/KR2009/007858
`
`3
`
`[Math.3]
`
`g: i'§1=§2="'=§:\:}i7 = P151=P2S2="'=PNTSN,i7
`
`[151 §
`
`may be expressed as a diagonal matrix
`
`P
`
`of transmit power.
`
`[16]
`
`MathFigure 4
`
`[Math.4]
`
`§ =
`
`P1
`
`0
`
`0
`
`S1
`
`.S2
`
`= PS
`
`P2
`
`.
`
`PM SN,
`
`[17]
`
`Meanwhile, actual NT transmitted signals
`
`x1,x2’...,x~_
`
`may be configured by applying a weight matrix
`
`W
`
`to the power—controlled information Vector
`/'\
`
`The weight matrix
`
`S .
`
`W
`
`functions to appropriately distribute the transmission information to the Tx antennas
`
`according to transmission channel statuses, etc. These transmitted signals
`
`x1,x2’...,x~_
`
`are represented as a Vector
`
`X
`
`, which may be determined as
`
`[18]
`
`MathFigure 5
`
`[Math.5]
`
`xl
`
`x2
`
`J:
`
`:
`
`x :
`
`W11
`
`W21
`
`W12
`
`W22
`
`‘ '
`
`'
`
`“"1313.
`
`Wan’,
`
`Wu
`
`we
`
`111$}
`
`31
`
`5;
`
`_
`S}
`
`: W'§ : WPS
`
`x_v\,rI
`
`w}gr1
`
`wj\V& _7,
`
`w:“.C-Iv} K SPJT
`
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`
`WO 2010/077051
`
`PCT/KR2009/007858
`
`[19]
`
`W.1/
`
`denotes a weight for a jib piece of information transmitted through an ith TX antenna.
`
`W i
`
`s also referred to as a precoding matrix.
`
`[20]
`
`Given NR RX antennas, signals received at the RX antennas,
`
`y1=y2>"'=J/NR
`
`may be represented as the following Vector.
`
`[21]
`
`MathFigure 6
`
`[Math.6]
`
`y 2 [y1=y2="'=yNRir
`
`[22]
`
`When channels are modeled in the MIMO communication system, they may be dis-
`
`tinguished according to the indexes of TX and RX antennas and the channel between a j
`
`th TX antenna and an im RX antenna may be represented as hi,-. It is to be noted herein
`
`that the indeX of the RX antenna precedes that of the TX antenna in hi,-.
`
`[23]
`
`The channels may be represented as Vectors and a matriX by grouping them. The
`
`Vector representation of channels may be carried out in the following manner.
`
`FIG. 2 illustrates channels from NT TX antennas to an ith RX antenna.
`
`Referring to FIG. 2, the channels from the NT TX antennas to the ith RX antenna may
`
`[24]
`
`[25]
`
`be eXpressed as the following Math Figure 7.
`
`[26]
`
`MathFigure 7
`
`[Math.7]
`
`= |_hz1> hi2: 7
`
`7 7 = hiN,.J
`
`[27]
`
`Also, all channels from NT TX antennas to NR RX antennas may be eXpressed as the
`
`following matriX.
`
`[28]
`
`MathFigure 8
`
`[Math.8]
`
`hf
`h:
`
`hm
`;721
`
`H : 7
`hir
`
`: I
`F121
`
`‘L52
`#322
`
`I/7:2
`
`"'
`"'
`
`I
`
`_
`
`h1N3-
`h2N;,
`
`hxmg
`
`h§R
`
`_;"r-.r;.,_1
`
`’7'_N_,,2
`
`'
`
`'
`
`'
`
`hNRN, i
`
`[29]
`
`Actual channels eXperience the aboVe channel matriX H and then are added with
`
`Additive White Gaussian Noise (AWGN). The AWGN
`
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`
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`
`n1>n2="'=nNR
`
`added to the NR RX antennas is given as the following vector.
`
`[30]
`
`MathFigure 9
`
`[Math.9]
`
`n = [n1,n2,---,nNR]r
`
`[31]
`
`[32]
`
`[33]
`
`[34]
`
`[35]
`
`From the above modeled equations, the received signal is given as
`
`MathFigure 10
`
`[Math. 10]
`
`yl
`J72
`
`.1’:
`
`1111
`I721
`
`I712
`fizz
`
`—
`
`I111
`
`[712
`
`y —
`
`yr»;
`
`173131
`
`£7.-V2 2
`
`z7=..r.3
`I]: .-‘-..i—
`
`— X1
`x2.
`
`+
`
`ht.-'z’—
`
`xj
`
`771
`"2
`
`nj
`
`ks.-;.‘~.;_ "xix";
`
`"NR
`
`' "
`
`I
`
`‘
`
`I
`
`'
`
`I
`
`'
`
`— Hx+ n
`
`(3) Channel Quality Indicator (CQI)
`
`For efficient communication, it is necessary to feed back channel information. In
`
`general, information about a downlink channel is transmitted on an uplink and in-
`
`formation about an uplink channel is transmitted on a downlink. This channel in-
`
`formation is called a CQI. The CQI may be generated in various manners.
`
`[36]
`
`For example, the CQI generation methods may include transmitting quantized
`
`channel state information a CQI, transmitting the Signal to Interference and Noise
`
`Ratio (SINR) of a channel as a CQI, and transmitting information indicating how a
`
`channel is actually used, such as a Modulation and Coding Scheme (MCS) level, as a
`
`CQI.
`
`[37]
`
`Many of the CQI generation methods generate a CQI based on an MCS. For
`
`example, a CQI is generated based on an MCS in 3“ Generation Partnership Project
`
`(3GPP) High Speed Downlink Packet Access (HSDPA). An MCS specifies a
`
`modulation scheme, a coding scheme, and a coding rate. Therefore, a CQI is changed
`
`if a modulation scheme and a coding scheme are changed and thus at least one CQI is
`
`required per codeword.
`
`[38]
`
`In a MIMO system, the number of required CQIs is changed. As the MIMO system
`
`generates multiple channels through multiple antennas, a plurality of codewords is
`
`available. Accordingly, a plurality of CQIs should be reported, thus increasing the
`
`amount of control information proportionally.
`
`[39]
`
`FIG. 3 illustrates the concept of CQI generation and CQI reporting. A User
`
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`Equipment (UE) measures a downlink channel quality and reports a CQI value selected
`
`based on the downlink channel quality measurement to a Base Station (BS) on an
`
`uplink control channel. The BS performs downlink scheduling based on CQI reports
`
`received from UEs. The downlink scheduling involves selecting a UE and allocating
`
`resources to the selected UE. A CQI value may be any of SINR, Carrier to Interference
`
`and Noise Ratio (CINR), Bit Error Rate (BER), and Frame Error rate (FER). Alter-
`
`natively, the CQI value may be a transn1ittable value as which one of the SINR, CINR,
`
`BER and FER is expressed. In the MIMO system, Rank Indicator (RI), Precoding
`
`[40]
`
`[41]
`
`Matrix Index (PMI), etc. may be added as channel state information.
`
`(4) Characteristics of CQI in Frequency Band
`
`In mobile communication systems, an MCS and transmit power are controlled for a
`
`given channel by link adaptation in order to fully utilize the capacity of the channel. To
`
`allow the BS to perform the link adaptation, the UE should feed back a CQI to the BS.
`
`[42]
`
`If a system frequency band has a bandwidth wider than a coherence bandwidth, a
`
`channel is changed greatly within one bandwidth. Particularly, a multi—carrier system
`
`such as an Orthogonal Frequency Division Multiplexing (OFDM) system uses a
`
`plurality of subcarriers in a given bandwidth and a modulated symbol is transmitted on
`
`every subcarrier. While it is optimal to transmit a channel per subcarrier, the amount of
`
`feedback channel information rapidly increases. In this context, many schemes have
`
`[43]
`
`[44]
`
`been proposed to reduce the control overhead.
`
`(5) Concept of Multi—Carrier
`
`The concept of multi—carrier and Component Carrier (CC) will be described below.
`
`FIG. 4 illustrates a frequency band in a multi—carrier system. Referring to FIG. 4, the
`
`multi—carrier represents a total frequency band available to a BS, equivalent to a whole
`
`band in its meaning. For example, the multi—carrier may be 100MHz.
`
`[45]
`
`A CC is an element of the multi—carrier. That is, a plurality of CCs form the multi-
`
`carrier by carrier aggregation. The CC includes a plurality of lower bands. If a multi-
`
`carrier is called a whole band, a CC may be referred to as a subband and a lower band
`
`may be referred to as a partial band. Carrier aggregation is intended to extend a
`
`bandwidth by aggregating a plurality of carriers in order to increase data rate. For
`
`example, a legacy system uses a carrier of 20MHz and the bandwidth of the carrier
`
`may be extended up to 100MHz by aggregating five 20—MHz carriers. The term
`
`"carrier aggregation" covers aggregating carriers in different frequency bands.
`
`[46]
`
`How to report the above—described CQI in the multi—carrier system becomes an issue
`
`to be solved.
`
`Disclosure of Invention
`
`Technical Problem
`
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`[47]
`
`An object of the present invention devised to solve the problem lies on a method for
`
`transmitting control information to request a CQI in a wireless communication system
`
`supporting a plurality of transmission bandwidths.
`
`[48]
`
`It will be appreciated by persons skilled in the art that that the objects that could be
`
`achieved with the present invention are not limited to what has been particularly
`
`described hereinabove and the above and other objects that the present invention could
`
`achieve will be more clearly understood from the following detailed description taken
`
`in conjunction with the accompanying drawings.
`
`Solution to Problem
`
`[49]
`
`The object of the present invention can be achieved by providing a method for
`
`transmitting control information to request a CQI in a wireless communication system
`
`supporting a plurality of transmission bands, which includes generating control in-
`
`formation including downlink transmission band indication information and CQI
`
`request information, the downlink transmission band indication information indicating
`
`a downlink transmission band requiring CQI reporting among a plurality of downlink
`
`transmission bands and the CQI request information requesting CQI reporting for the
`
`downlink transmission band, and transmitting the generated control information on a
`
`downlink control channel of a predetermined downlink transmission band among the
`
`plurality of downlink transmission bands.
`
`[50]
`
`In another aspect of the present invention, provided herein is a method for
`
`transmitting CQI information in a wireless communication system supporting a
`
`plurality of transmission bands, including receiving from a BS control information
`
`including CQI request information requesting CQI reporting and an uplink grant for
`
`uplink scheduling on a downlink control channel of one of a plurality of downlink
`
`transmission bands, and transmitting CQI information for the downlink transmission
`
`band on an uplink shared channel of an uplink transmission band indicated by the
`
`uplink grant among a plurality of uplink transmission bands.
`
`[51]
`
`In another aspect of the present invention, provided herein is a method for
`
`transmitting CQI information in a wireless communication system supporting a
`
`plurality of transmission bands, which includes receiving from a BS control in-
`
`formation including CQI request information requesting CQI reporting and an uplink
`
`grant for uplink scheduling on a downlink control channel in one of a plurality of
`
`downlink transmission bands, and transmitting CQI information for a downlink
`
`transmission band corresponding to an uplink transmission band indicated by the
`
`uplink grant on an uplink shared channel of the uplink transmission band.
`
`[52]
`
`In another aspect of the present invention, provided herein is a BS in a wireless com-
`
`munication system supporting a plurality of transmission bands, which includes a
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`
`ERICSSON INC. EX. NO. 1011
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`ERICSSON INC. EX. NO. 1011
`
`

`
`WO 2010/077051
`
`PCT/KR2009/007858
`
`processor unit for generating control information including downlink transmission
`
`band indication information and CQI request information, the downlink transmission
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`band indication information indicating a downlink transmission band requiring CQI
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`reporting among a plurality of downlink transmission bands and the CQI request in-
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`formation requesting CQI reporting for the downlink transmission band, and an RF
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`unit electrically connected to the processor unit, for transmitting the generated control
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`information on a downlink control channel of a predetermined downlink transmission
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`band among the plurality of downlink transmission bands.
`
`[53]
`
`In another aspect of the present invention, provided herein is a UE in a wireless com-
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`munication system supporting a plurality of transmission bands, which includes a
`
`receiver for receiving from a BS control information, which includes CQI request in-
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`formation requesting CQI reporting and an uplink grant for uplink scheduling on a
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`downlink control channel of one of a plurality of downlink transmission bands, a
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`processor electrically connected to the receiver, for generating CQI information for the
`
`downlink transmission band, and a transmitter electrically connected to the processor,
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`for transmitting the CQI information on an uplink shared channel indicated by the
`
`uplink grant.
`
`[54]
`
`In a further aspect of the present invention, provided herein is a UE in a wireless
`
`communication system supporting a plurality of transmission bands, which includes a
`
`receiver for receiving from a BS control information including CQI request in-
`
`formation requesting CQI reporting and an uplink grant for uplink scheduling on a
`
`downlink control channel in one of a plurality of downlink transmission bands, a
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`processor electrically connected to the receiver, for generating CQI information for a
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`downlink transmission band corresponding to an uplink transmission band indicated by
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`the uplink grant, and a transmitter electrically connected to the processor, for
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`transmitting the CQI on an uplink shared channel of the uplink transmission band.
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`Advantageous Effects of Invention
`
`[55]
`
`According to the present invention, signaling can be effectively configured, when
`
`control information is transmitted to request CQI reporting in a multi—carrier system.
`
`[56]
`
`It will be appreciated by persons skilled in the art that that the effects that could be
`
`achieved with the present invention are not limited to what has been particularly
`
`described hereinabove and other advantages of the present invention will be more
`
`clearly understood from the following detailed description taken in conjunction with
`
`the accompanying drawings.
`
`Brief Description of Drawings
`
`[57]
`
`The accompanying drawings, which are included to provide a further understanding
`
`of the invention, illustrate embodiments of the invention and together with the de-
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`
`ERICSSON INC. EX. NO. 1011
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`ERICSSON INC. EX. NO. 1011
`
`

`
`WO 2010/077051
`
`PCT/KR2009/007858
`
`[58]
`
`[59]
`
`scription serve to explain the principle of the invention.
`
`In the drawings:
`
`FIG. 1 illustrates the configuration of a typical Multiple Input Multiple Output
`
`(MIMO) communication system;
`
`[60]
`
`FIG. 2 illustrates channels from NT Transmission (Tx) antennas to an im Reception
`
`(Rx) antenna;
`
`[61]
`
`FIG. 3 illustrates the concept of Channel Quality Indicator (CQI) generation and CQI
`
`reporting;
`
`[62]
`
`[63]
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`FIG. 4 illustrates a frequency band in a multi—carrier system;
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`FIG. 5 illustrates a method for selecting CQI subbands in the frequency domain and
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`generating CQIs for the selected CQI subbands;
`
`[64]
`
`FIG. 6 illustrates transmission bands when each of a downlink and an uplink uses a
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`single Component Carrier (CC);
`
`[65]
`
`FIG. 7 illustrates transmission bands when each of a downlink and an uplink uses a
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`plurality of (CCs);
`
`[66]
`
`FIG. 8 illustrates the configuration of control information fields used to request CQI
`
`reporting and a CQI transmission method in a multi—carrier system according to an
`
`exemplary embodiment of the present invention;
`
`[67]
`
`FIG. 9 illustrates the configuration of control information fields used to request CQI
`
`reporting and a CQI transmission method in the multi—carrier system according to
`
`another exemplary embodiment of the present invention;
`
`[68]
`
`FIG. 10 illustrates a method for configuring control information for CQI reporting in
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`the multi—carrier system according to another exemplary embodiment of the present
`
`invention;
`
`[69]
`
`FIG. ll illustrates the configuration of control information fields used to request CQI
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`reporting in the multi—carrier system according to another exemplary embodiment of
`
`the present invention;
`
`[70]
`
`FIG. 12 illustrates the configuration of control information fields used to request CQI
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`reporting in the multi—carrier system according to another exemplary embodiment of
`
`the present invention; and
`
`[71]
`
`FIG. 13 is a block diagram of an apparatus that is applicable to a User Equipment
`
`(UE) or a Base Station (BS), for implementing the above exemplary embodiments of
`
`the present invention, according to a further exemplary embodiment of the present
`
`invention.
`
`Best Mode for Carrying out the Invention
`
`[72]
`
`Reference will now be made in detail to the exemplary embodiments of the present
`
`invention with reference to the accompanying drawings. The detailed description,
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`
`ERICSSON INC. EX. NO. 1011
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`ERICSSON INC. EX. NO. 1011
`
`

`
`WO 2010/077051
`
`PCT/KR2009/007858
`
`10
`
`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 invention. The following de-
`
`scription 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. The same reference
`
`numbers will be used throughout this specification to refer to the same or like parts.
`
`[73]
`
`Before describing methods for reporting a CQI in a multi—carrier system according to
`
`the present invention, a description will first be made of CQI generation schemes.
`
`[74]
`
`[75]
`
`[76]
`
`(1) CQI Generation Schemes
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`Along with the increase of channel information in amount, control signaling is also
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`increased. To reduce the control overhead, a CQI is generated in the manner that
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`reduces the information amount of the CQI. For this purpose, the following CQI
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`generation schemes have been designed.
`
`[77]
`
`One of the CQI generation schemes is to change a unit about which a CQI is
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`transmitted. In an Orthogonal Frequency Division Multiplexing (OFDM) system, for
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`example, a CQI is transmitted on a subcarrier group basis instead of transmitting a CQI
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`for every subcarrier. Given a total of 2048 subcarriers, the subcarriers are grouped into
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`l7l subcarrier groups each including 12 subcarriers. As a consequence, the number of
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`actually transmitted CQIs decreases from 2048 to l7l.
`
`[78]
`
`In the case where a frequency band is divided into an integer number of subcarriers
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`as in OFDM, the subcarriers are grouped into subcarrier groups each including one or
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`more subcarriers and a CQI is reported on a subcarrier group basis. Thus a basic CQI
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`reporting unit may be a subcarrier group which is defined as a CQI subcarrier group in
`
`the present invention. On the other hand, in the case where a frequency band is not
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`divided into sucarriers, the total frequency band is divided into subbands and a CQI is
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`generated on a subband basis. Thus, a basic CQI reporting unit may be a subband
`
`which is defined as a CQI subband in the present invention.
`
`[79]
`
`Another CQI generation scheme is to generate a CQI by compressing channel in-
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`formation. For example, channel information per subcarrier is compressed by a certain
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`compression method in the OFDM system. The compression method may be a
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`Discrete Cosign Transform (DCT), etc.
`
`[80]
`
`A third CQI generation scheme is to generate a CQI for a selected frequency band.
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`For example, in the OFDM system, M best subcarriers or subcarrier groups are
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`selected from among total subcarriers or subcarrier groups and CQIs concerning the M
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`best subcarriers or subcarrier groups are transmitted, rather than a CQI is transmitted
`
`for every subcarrier. This scheme is called a Best—M scheme.
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`
`ERICSSON INC. EX. NO. 1011
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`ERICSSON INC. EX. NO. 1011
`
`

`
`WO 2010/077051
`
`PCT/KR2009/007858
`
`11
`
`[81]
`
`When a CQI is transmitted for a selected frequency band, two information parts are
`
`actually transmitted, a CQI value and a CQI index.
`
`[82]
`
`[83]
`
`[84]
`
`(2) Generation of CQIs for Selected Frequency Bands
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`FIG. 5 illustrates a method for selecting CQI subbands in the frequency domain and
`
`generating CQIs for the selected CQI subbands. The frequency band—selective CQI
`
`generation involves three steps on the whole.
`
`[85]
`
`In Step 1, frequency bands for which CQIs are to be generated, that is, CQI subbands
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`are selected. Then CQI values are generated for the selected CQI subbands and
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`transmitted in Step 2 and the indexes of the selected CQI subbands are transmitted in
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`Step 3.
`
`[86]
`
`In FIG. 5, the Best—M scheme and a threshold—based scheme are presented as
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`examples of selecting CQI subbands. The Best—M scheme selects M CQI subbands in
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`good channel status. In the illustrated case of FIG. 5, CQI subbands with indexes 5, 6
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`and 9 in good channel status are selected according to a Best—3 scheme. Meanwhile,
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`the threshold—based scheme selects CQI subbands in channel statuses exceeding a pre-
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`determined threshold. It is shown in FIG. 5 that CQI subbands with indexes 5 and 6 in
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`channel statuses exceeding a threshold are selected.
`
`[87]
`
`As examples of generating and transmitting CQI values, an individual transmission
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`scheme and an average transmission scheme are illustrated in FIG. 5. CQI values for
`
`the selected CQI subbands are all transmitted in the individual transmission scheme.
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`Therefore, as more CQI subbands are selected, more CQI values are transmitted.
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`Meanwhile, the average transmission scheme is to transmit the average of CQI values
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`for the selected CQI subbands. Thus despite the advantage of transmission of a single
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`CQI value irrespective of the number of selected CQI subbands, CQI accuracy is
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`decreased. The average of CQI values may be an arithmetic average or a channel
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`capacity—based average.
`
`[88]
`
`A bitmap index scheme and a combinatorial index scheme are illustrated as examples
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`of transmitting the indexes of the CQI subbands in FIG. 5. In the bitmap index scheme,
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`one bit is mapped to each CQI subband. The bit is set to l for a selected CQI subband
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`and to 0 for a non—selected CQI subband. The bitmap index scheme requires as many
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`bits as total CQI subbands and thus a bitmap is represented always in the same number
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`of bits irrespective of the number of selected CQI subbands. Compared to the bitmap
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`index scheme, the number of selected CQI subbands is determined and then each of all
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`possible cases that may be produced by combining as many CQI subbands as the de-
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`termined number is mapped to an index in the combinatorial index scheme.
`
`[89]
`
`More specifically, given a total of N CQI subbands, if M CQI subbands are selected,
`
`the total number of possible combinations each having M CQI subbands is calculated
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`
`ERICSSON INC. EX. NO. 1011
`
`TELEFONAKTIEBOLAGET LM ERICSSON AND
`ERICSSON INC. EX. NO. 1011
`
`

`
`WO 2010/077051
`
`PCT/KR2009/007858
`
`12
`
`by
`
`[90]
`
`MathFigure 11
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`[Math.11]
`
`N!
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`NCM
`
`[91]
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`The number of bits required to represent as many combination cases as the number
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`determined by [Equation 11] is given as
`
`[92]
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`MathFigure 12
`
`[Math. 12]
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`[1082(NCM = [108
`
`N!
`
`[93]
`
`where
`
`[ ]
`
`represents a ceiling function.
`
`[94]
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`In FIG. 5, three CQI subbands are selected from among 11 CQI subbands in total and
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`thus the number of possible combinations each having three CQI subbands is 11C3=165
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`that satisfies
`
`27 3,, C, s 2*
`
`. Hence, eight bits are needed to represent the 165 combinations.
`
`[95]
`
`CQIs may increase in number in various dimensions, causing a great overhead,
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`which will be described below.
`
`[96]
`
`[97]
`
`[98]
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`(3) Increase of CQIs in Number in Many Domains
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`Regarding an increase in the number of CQIs in the spatial domain, when a MIMO
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`system transmits a plurality of codewords through a plurality of layers, a plurality of
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`CQIs is required accordingly. For example, up to two codewords are available and thus
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`two CQIs are needed in a 3“ Generation Partnership Project Long Term Evolution
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`(3GPP LTE)—MIMO system. Assuming that one CQI occupies 4 bits and two
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`codewords exist, CQIs requ