throbber
(12) United States Patent
`Kwak et a].
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 7,852,883 B2
`Dec. 14, 2010
`
`US007852883B2
`
`(75)
`
`(54) METHOD OF TRANSMITTING UPLINK
`CONTROL SIGNALS IN WIRELESS
`COMMUNICATION SYSTEM
`Inventors: Jin Sam Kwak, Anyang-si (KR); Hong
`Won Park, Anyang-si (KR); Seung Hee
`Han, Anyang-si (KR); Min Seok Noh,
`Anyang-si (KR); Yeong Hyeon KWon,
`Anyang-si (KR); Hyun Woo Lee,
`Anyang-si (KR); Dong Cheol Kim,
`Anyang-si (KR); Jae Hoon Chung,
`Anyang-si (KR)
`
`(73)
`
`Assignee: LG Electronics Inc., Seoul (KR)
`
`(*)
`
`Notice:
`
`(21)
`(22)
`
`(86)
`
`(87)
`
`(65)
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`USC 154(b) by 0 days.
`12/594,159
`Aug. 7, 2008
`
`Appl. No .:
`PCT Filed:
`
`PCT No.:
`
`PCT/KR2008/004590
`
`§ 371 (0X1)’
`(2), (4) Date:
`
`Sep. 30, 2009
`
`PCT Pub. No.: WO2009/020358
`
`PCT Pub. Date: Feb. 12, 2009
`
`Prior Publication Data
`
`US 2010/0046460 A1
`
`Feb. 25, 2010
`
`Related US. Application Data
`
`(52) U.S. c1. .................................................... .. 370/522
`(58) Field of Classi?cation Search ................ .. 370/522
`See application ?le for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`2007/0133458 A1
`
`6/2007 Chandra et al.
`
`(Continued)
`FOREIGN PATENT DOCUMENTS
`
`KR
`
`10-2007-0074431 A
`
`7/2007
`
`(Continued)
`OTHER PUBLICATIONS
`
`Source: LG Electronics Inc., 3GPP TSG RAN WGI #51; “Schedul
`ing Request (SR) interaction With PUCCH”; Agenda Item: 6.2.4;
`Document for: Discussion and Decision; Jeju, Korea; Nov. 5-9, 2007;
`R1-074739.
`
`(Continued)
`Primary ExamineriMelvin Marcelo
`(74) Attorney, Agent, or FirmiBirch, Stewart, Kolasch &
`Birch, LLP
`
`(57)
`
`ABSTRACT
`
`A method of transmitting uplink control signals in a Wireless
`communication system includes preparing a ACK/NACK
`resource for transmitting the ACK/NACK signal for HARQ
`of doWnlink data on an uplink control channel, preparing a
`scheduling request resource for transmitting a scheduling
`request and the ACK/NACK signal on the uplink control
`channel in one subframe, and transmitting the ACK/NACK
`signal on the uplink control channel con?gured by the sched
`uling request resource for the positive transmission of the
`scheduling request and transmitting the ACK/NACK signal
`on the uplink control channel con?gured by the ACK/NACK
`resource for negative transmission of the scheduling request.
`
`14 Claims, 11 Drawing Sheets
`
`(60)
`
`Provisional application No. 60/954,812, ?led on Aug.
`8, 2007, provisional application No. 60/979,860, ?led
`on Oct. 14, 2007.
`Foreign Application Priority Data
`(30)
`Dec. 7, 2007
`
`(KR) .................... .. 10-2007-0127014
`
`(51)
`
`Int. Cl.
`H04B 7/26
`
`(2006.01)
`
`~Time
`Freq.
`
`SR Signal
`SR-Related Data
`
`(1)
`
`(2)
`
`ACK/NACK Signal-0i;
`
`SR TriggeringiT
`
`(3)
`
`SR Channel
`
`{Coherent SR+SR-Re|ated Data Detection
`(1)
`Non-coherent SR
`+ Coherent SR-Related Data Detection
`
`(2)
`
`Non-coherent SR
`+ Coherent ACK/NACK Detection
`
`W» Coherent ACK/NACK Detection
`
`ACK/NACK Channel
`
`1
`
`HUAWEI 1005
`
`

`

`US 7,852,883 B2
`Page 2
`
`US. PATENT DOCUMENTS
`
`7/2007 Zhang et a1.
`2007/0171849 A1
`2007/020l397 Al* 8/2007 Zhang ...................... .. 370/329
`2009/0l099l7 Al *
`4/2009 Pajukoski et al. ......... .. 370/329
`20l0/0l95629 Al *
`8/2010 Chen et al. ................ .. 370/336
`
`FOREIGN PATENT DOCUMENTS
`
`l0-2008-00736l6 A
`KR
`WO WO-2009/008677 A2
`WO WO-2007/078l7l A2
`
`8/2008
`1/2009
`7/2009
`
`OTHER PUBLICATIONS
`
`Rl-070l62, “EUTRA UL Ll/L2 Control Channel Mapping,”
`Motorola, RANl#47bis, Sorrento, Italy, Jan. 2007.
`Alcatel-Lucent: “Multiplexing the Scheduling Request in the
`Uplink” ; 5.13.2 UL Control Signaling; 3GPP TSG-RAN WGl
`#49bis; Rl-073066; Orlando U.S., Jun. 25-29, 2007; XP050106721.
`Nokia Siemens Networks, Nokia; Multiplexing of Scheduling
`Request and ACK/NACK and/or CQI; 3GPP TSG RAN WGl
`#49bis; Rl-07300l; 5.13.2; Orlando, U.S.A., Jun. 25-29, 2007;
`XP050106675.
`Ericsson: ‘Detail of ACK/NAK bundling for TDD’; TSG-RAN WGl
`#53; Rl-082002; 7.1.2; Kansas City, MO, USA, May 5-9, 2008;
`XP050ll0349.
`
`Rl -070777, “E-UTRA Multiplexing of UL Control Signaling With
`Data,” Motorola, RANl#48, St. Louis, USA, Feb. 2007.
`
`* cited by examiner
`
`2
`
`

`

`US. Patent
`
`Dec. 14, 2010
`
`Sheet 1 0f 11
`
`US 7,852,883 B2
`
`[Fig. 1]
`
`[Fig. 2]
`
`._.".
`
`'—'\ll
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`100
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`#1
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`#2
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`#18
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`#19
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`
`3
`
`

`

`US. Patent
`
`Dec. 14, 2010
`
`Sheet 2 0f 11
`
`US 7,852,883 B2
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`[Fig.4]
`
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`

`

`US. Patent
`
`Dec. 14, 2010
`
`Sheet 3 0f 11
`
`US 7,852,883 B2
`
`[Fig. 6]
`
`.2 Time Domain Sequence
`for SR signal
`
`
`
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`
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`

`

`US. Patent
`
`Dec. 14, 2010
`
`Sheet 4 0f 11
`
`US 7,852,883 B2
`
`[Fig.7]
`
`2
`‘ Reserved Time-Domain
`Sequence for SR signal
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`
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`
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`
`Reserved Time-Frequency Domain
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`
`6
`
`

`

`US 7,852,883 B2
`
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`

`US. Patent
`
`Dec. 14, 2010
`
`Sheet 6 0f 11
`
`US 7,852,883 B2
`
`[Fig. 10]
`
`Time Domain Sequence
`for SR slgnal
`
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`

`

`US. Patent
`
`Dec. 14, 2010
`
`Sheet 7 0f 11
`
`US 7,852,883 B2
`
`[Fig. 11]
`
`_
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`Sequence(s) For SR signal
`
`Code
`
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`
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`
`9
`
`

`

`U.S. Patent
`
`4a
`
`11f000
`
`US 7,852,883 B2
`
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`

`US. Patent
`
`Dec. 14, 2010
`
`Sheet 9 0f 11
`
`US 7,852,883 B2
`
`[Fig. 14]
`
`Reserved Block-Spreading
`2
`\ Codes for SR with Length 4
`
`853$ 0M ,6 £5 0:26
`
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`Sequence #1
`with Length 3
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`
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`Codes for SR with Length 3
`
`11
`
`

`

`U.S. Patent
`
`Dec. 14, 2010
`
`Sheet 10 0f 11
`
`US 7,852,883 B2
`
`[Fig. 15]
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`

`US. Patent
`
`Dec. 14, 2010
`
`Sheet 11 0111
`
`US 7,852,883 B2
`
`jACK/NACK SR Signal
`
`1 slot
`
`1 slot
`
`[Fig. 16]
`
`
`
`Data Region
`
`ACK/NACK T SR Signal
`
`[Fig. 17]
`
`Phase Rotation/
`Onhogonal sequenoe/
`Differential
`modulation for SR signal
`
`ACK/NACK
`
`13
`
`

`

`US 7,852,883 B2
`
`1
`METHOD OF TRANSMITTING UPLINK
`CONTROL SIGNALS IN WIRELESS
`COMMUNICATION SYSTEM
`
`This application is the National Phase of PCT/KR2008/
`004590 ?led on Aug. 7, 2008, Which claims priority under 35
`U.S.C. ll9(e) to US. Provisional Application Nos. 60/954,
`812 ?led on Aug. 8, 2007 and 60/979,860 ?led on Oct. 14,
`2007, and under 35 U.S.C. l 19(a) to Patent Application No.
`10-2007-0127014 ?led in Korea on Dec. 7, 2007, all of Which
`are hereby expressly incorporated by reference into the
`present application.
`
`TECHNICAL FIELD
`
`The present invention relates to Wireless communications,
`and more particularly, to a method of transmitting uplink
`control signals in a Wireless communication system.
`
`BACKGROUND ART
`
`20
`
`2
`radio resource. The scheduling request is a sort of preliminary
`information exchange for data exchange. In order for the UE
`to transmit uplink data to the BS, radio resource allocation is
`?rst requested by using the scheduling request. When the BS
`allocates the uplink radio resource in response to the sched
`uling request, the UE transmits the uplink data by using the
`allocated radio resource.
`Compatibility With another control channel for transmit
`ting another control signal has to be taken into consideration
`When the scheduling request needs to be transmitted on an
`uplink control channel. UE capacity capable of transmitting
`the scheduling request has to be also taken into consideration.
`A case Where the scheduling request is transmitted simulta
`neously With other control signals has to be also taken into
`consideration. For example, the scheduling request andACK/
`NACK signals may be simultaneously transmitted by one UE.
`Accordingly, there is a need for a control channel having an
`effective structure for simultaneously transmitting a schedul
`ing request and other control signals.
`
`DISCLOSURE OF INVENTION
`
`Technical Problem
`
`The present invention provides a method of transmitting a
`plurality of multiplexed uplink control signals.
`The present invention also provides a method of transmit
`ting a scheduling request for requesting uplink radio resource
`allocation together With other control signals through one
`uplink control channel.
`
`Technical Solution
`
`In an aspect, a method of transmitting uplink control sig
`nals in a Wireless communication system is provided. The
`method includes preparing a scheduling request resource for
`transmitting a scheduling request on an uplink control chan
`nel in one subframe, a subframe comprising tWo slots, a slot
`comprising a plurality of single carrier-frequency division
`multiple access (SC-FDMA) symbols, the scheduling request
`being used to request a radio resource for uplink transmission,
`Wherein a positive transmission of the scheduling request is
`carried by presence of its transmission on the uplink control
`channel and a negative transmission of the scheduling request
`is carried by absence of its transmission on the uplink control
`channel, preparing an ACK/NACK resource for transmitting
`an ACK/NACK signal for hybrid automatic repeat request
`(HARQ) of doWnlink data on the uplink control channel in
`one subframe, and When both the ACK/NACK signal and the
`scheduling request are transmitted in same subframe, trans
`mitting the ACK/NACK signal on the uplink control channel
`Which is con?gured by the scheduling request resource for the
`positive transmission of the scheduling request and transmit
`ting the ACK/NACK signal on the uplink control channel
`Which is con?gured by the ACK/NACK resource for the
`negative transmission of the scheduling request.
`The uplink control channel may be con?gured by dividing
`the plurality of SC-FDMA symbols in the slot into a ?rst set
`of SC-FDMA symbols and a second set of SC-FDMA sym
`bols, spreading a control signal With each of ?rst frequency
`domain sequences, the ?rst frequency domain sequences
`being generated by cyclic shifts of a base sequence, Wherein
`the control signal corresponds to the scheduling request or the
`ACK/NACK signal, mapping the spread control signals to
`each SC-FDMA symbol in the ?rst set, mapping each of
`second frequency domain sequences to each SC-FDMA sym
`bol in the second set, the second frequency domain sequence
`
`25
`
`30
`
`35
`
`40
`
`In order to maximize ef?ciency of a limited radio resource
`in a Wideband Wireless communication system, methods for
`more effectively transmitting data in time, spatial, and fre
`quency domains have been provided.
`Orthogonal frequency division multiplexing (OFDM) uses
`a plurality of orthogonal subcarriers. Further, the OFDM uses
`an orthogonality betWeen inverse fast Fourier transform
`(IFFT) and fast Fourier transform (FFT). A transmitter trans
`mits data by performing IFFT. A receiver restores original
`data by performing FFT on a received signal. The transmitter
`uses IFFT to combine the plurality of subcarriers, and the
`receiver uses FFT to split the plurality of subcarriers. Accord
`ing to the OFDM, complexity of the receiver can be reduced
`in a frequency selective fading environment of a broadband
`channel, and spectral e?iciency can be increased When selec
`tive scheduling is performed in a frequency domain by using
`a channel characteristic Which is different from one subcarrier
`to another. Orthogonal frequency division multiple access
`(OFDMA) is an OFDM-based multiple access scheme.
`According to the OFDMA, ef?ciency of radio resources can
`be increased by allocating different subcarriers to multiple
`users.
`To maximiZe ef?ciency in the spatial domain, the OFDM/
`OFDMA-based system uses a multiple-antenna technique
`45
`Which is used as a suitable technique for high-speed multi
`media data transmission by generating a plurality of time/
`frequency domains in the spatial domain. The OFDM/
`OFDMA-based system also uses a channel coding scheme for
`effective use of resources in the time domain, a scheduling
`scheme Which uses a channel selective characteristic of a
`plurality of users, a hybrid automatic repeat request (HARQ)
`scheme suitable for packet data transmission, etc.
`In order to implement various transmission or reception
`methods to achieve high-speed packet transmission, trans
`mission of a control signal on the time, spatial, and frequency
`domains is an essential and indispensable factor. A channel
`for transmitting the control signal is referred to as a control
`channel. An uplink control signal may be various such as an
`acknowledgement
`(ACK)/negative-acknoWledgement
`(NACK) signal as a response for doWnlink data transmission,
`a channel quality indicator (CQI) indicating doWnlink chan
`nel quality, a preceding matrix index (PMI), a rank indicator
`(RI), etc.
`One example of the uplink control signal is a scheduling
`request. The scheduling request is used When a user equip
`ment (UE) requests a base station (BS) to allocate an uplink
`
`50
`
`55
`
`60
`
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`
`14
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`

`US 7,852,883 B2
`
`3
`being generated by cyclic shifts of the base sequence, spread
`ing the mapped control signals in the ?rst set With a ?rst
`orthogonal sequence, the ?rst orthogonal sequence having a
`length equal to the number of SC-FDMA symbols in the ?rst
`set, and spreading the mapped second frequency domain
`sequences in the second set With a second orthogonal
`sequence, the second orthogonal sequence having a length
`equal to the number of SC-FDMA symbols in the second set.
`In another aspect, a method of transmitting uplink control
`signals in a Wireless communication system is provided. The
`method includes preparing a scheduling request resource for
`simultaneously transmitting a scheduling request and an
`ACK/NACK signal on an uplink control channel in a sub
`frame, the subframe comprising tWo slots, a slot comprising a
`plurality of SC-FDMA symbols, the scheduling request being
`used to request a radio resource for uplink transmission, and
`transmitting the ACK/NACK signal and the scheduling
`request on the uplink control channel Which is con?gured by
`the scheduling request resource When both the ACK/NACK
`signal and the scheduling request are transmitted in the sub
`frame.
`In still another aspect, a method of transmitting uplink
`control signals in a Wireless communication system is pro
`vided. Both an ACK/NACK signal and a scheduling request
`may be transmitted in same subframe. The method includes
`preparing a ACK/NACK resource for transmitting the ACK/
`NACK signal for HARQ of doWnlink data on an uplink con
`trol channel, preparing a scheduling request resource for
`transmitting a scheduling request and the ACK/NACK signal
`on the uplink control channel in one subframe, the one sub
`frame comprising tWo slots, a slot comprising a plurality of
`SC-FDMA symbols, the scheduling request being used to
`request a radio resource for uplink transmission, Wherein a
`positive transmission of the scheduling request is carried by
`presence of its transmission on the uplink control channel and
`a negative transmission of the scheduling request is carried by
`absence of its transmission on the uplink control channel, and
`transmitting the ACK/NACK signal on the uplink control
`channel con?gured by the scheduling request resource for the
`positive transmission of the scheduling request and transmit
`ting the ACK/NACK signal on the uplink control channel
`con?gured by the ACK/NACK resource for negative trans
`mission of the scheduling request.
`Advantageous Effects
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`A scheduling request and an acknowledgment (ACK)/
`negative-acknowledgement (NACK) signal can be simulta
`neously transmitted in the same subframe Without interfer
`ence With other control channels. Even When the scheduling
`request is simultaneously transmitted With other control sig
`nals, there is no performance deterioration in detection of the
`control signals. The scheduling request can be transmitted
`While minimiZing decrease in capability of the control chan
`nels.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 shoWs a Wireless communication system.
`FIG. 2 is a block diagram shoWing a transmitter according
`to an embodiment of the present invention.
`FIG. 3 shoWs an exemplary structure of a radio frame.
`FIG. 4 shoWs an exemplary subframe.
`FIG. 5 shoWs a structure of an acknowledgement (ACK)/
`negative-acknowledgement (NACK) channel.
`FIG. 6 shoWs an example of a con?guration of a scheduling
`request channel for coherent detection according to an
`embodiment of the present invention.
`
`50
`
`55
`
`60
`
`65
`
`4
`FIG. 7 shoWs an example of a con?guration of a scheduling
`request channel for coherent detection according to another
`embodiment of the present invention.
`FIG. 8 shoWs an example of a con?guration of a scheduling
`request channel for coherent detection according to another
`embodiment of the present invention.
`FIG. 9 shoWs an example of transmission of a scheduling
`request.
`FIG. 10 shoWs an example of a con?guration of a sched
`uling request channel for non-coherent detection according to
`an embodiment of the present invention.
`FIG. 11 shoWs an example of a con?guration of a sched
`uling request channel for non-coherent detection according to
`another embodiment of the present invention.
`FIG. 12 shoWs an example of a con?guration of a sched
`uling request channel for non-coherent detection according to
`another embodiment of the present invention.
`FIG. 13 shoWs an example of transmission of a scheduling
`request.
`FIG. 14 shoWs an example of a con?guration of a sched
`uling request channel according to an embodiment of the
`present invention.
`FIG. 15 shoWs an example of transmission of a scheduling
`request.
`FIG. 16 shoWs an example of transmission of a scheduling
`request of slot-based hopping.
`FIG. 17 shoWs an example of a slot structure for transmit
`ting a scheduling request.
`
`MODE FOR THE INVENTION
`
`FIG. 1 shoWs a Wireless communication system. The Wire
`less communication system can be Widely deployed to pro
`vide a variety of communication services, such as voices,
`packet data, etc.
`Referring to FIG. 1, the Wireless communication system
`includes at least one user equipment (UE) 10 and a base
`station (BS) 20. The UE 10 may be ?xed or mobile, and may
`be referred to as another terminology, such as a mobile station
`(MS), a user terminal (UT), a subscriber station (SS), a Wire
`less device, etc. The BS 20 is generally a ?xed station that
`communicates With the UE 10 and may be referred to as
`another terminology, such as a node-B, a base transceiver
`system (BTS), an access point, etc. There are one or more
`cells Within the coverage of the BS 20.
`Hereinafter, a doWnlink is de?ned as a communication link
`from the BS 20 to the UE 10, and an uplink is de?ned as a
`communication link from the UE 10 to the BS 20. In the
`doWnlink, a transmitter may be a part of the BS 20, and a
`receiver may be a part of the UE 10. In the uplink, the trans
`mitter may be a part of the UE 10, and the receiver may be a
`part ofthe BS 20.
`FIG. 2 is a block diagram shoWing a transmitter according
`to an embodiment of the present invention.
`Referring to FIG. 2, a transmitter 100 includes a transmit
`(Tx) processor 110, a discrete Fourier transform (DFT) unit
`120 that performs DFT, and an inverse fast Fourier transform
`(IFFT) unit 130 that performs IFFT. The DFT unit 120 per
`forms DFT on data processed by the Tx processor 110 and
`outputs a frequency domain symbol. The data input to the
`DFT unit 120 may be a control signal and/or user data. The
`IFFT unit 130 performs IFFT on the received frequency
`domain symbol and outputs a Tx signal. The Tx signal is a
`time domain signal and is transmitted through a Tx antenna
`190. A time domain symbol output from the IFFT unit 130 is
`referred to as an orthogonal frequency division multiplexing
`(OFDM) symbol. Since IFFT is performed after DFT spread
`
`15
`
`

`

`US 7,852,883 B2
`
`5
`ing, the time domain symbol output from the IFFT unit 130 is
`also referred to as a single carrier-frequency division multiple
`access (SC-FDMA) symbol. SC-FDMA is a scheme in Which
`spreading is achieved by performing DFT at a previous stage
`of the IFFT unit 130 and is advantageous over the OFDM in
`terms of decreasing a peak-to-average poWer ratio (PAPR).
`Although the SC-FDMA scheme is described herein, mul
`tiple access schemes used in the present invention are not
`limited thereto. For example, various multiple access
`schemes may be used such as code division multiple access
`(CDMA), time division multiple access (TDMA), frequency
`division multiple access (FDMA), single-carrier FDMA (SC
`FDMA), orthogonal frequency division multiple access
`(OFDMA), etc.
`Different multiple access schemes may be used for uplink
`and doWnlink in the Wireless communication system. For
`example, the SC-FDMA scheme may be used for uplink, and
`the OFDMA scheme may be used for doWnlink.
`FIG. 3 shoWs an exemplary structure of a radio frame.
`Referring to FIG. 3, the radio frame includes 10 subframes.
`One subframe can include tWo slots. One slot can include a
`plurality of OFDM symbols in a time domain and at least one
`subcarrier in a frequency domain. The slot is a unit of radio
`resource allocation in the time domain. For example, one slot
`can include 7 or 6 OFDM symbols.
`The radio frame structure is shoWn for exemplary purposes
`only, and thus the number of subframes included in the radio
`frame or the number of slots included in the subframe or the
`number of OFDM symbols included in the slot is not limited
`thereto.
`FIG. 4 shoWs an exemplary subframe. The subframe may
`be an uplink subframe using SC-FDMA.
`Referring to FIG. 4, the uplink subframe can be divided
`into tWo parts, that is, a control region and a data region. Since
`the control region and the data region use different frequency
`bands, frequency division multiplexing (FDM) have been
`achieved.
`The control region is used to transmit only a control signal
`and is generally assigned to a control channel. The data region
`is used to transmit data and is generally assigned to a data
`channel. An uplink control channel assigned to the control
`region is referred to as a physical uplink control channel
`(PUCCH). An uplink data channel assigned to the data region
`is referred to as a physical uplink shared channel (PUSCH).
`The control channel transmits the control signal. The data
`channel transmits the user data. The control signal includes a
`plurality of signals other than the user data. That is, the
`control signal includes an acknowledgement (ACK)/nega
`tive-acknowledgement (NACK) signal, a channel quality
`indicator (CQI), a preceding matrix index (PMI), a rank indi
`cator (RI), a scheduling request, etc.
`Only the control signal is carried on the control region. The
`user data and the control signal can be carried together on the
`data region. That is, When a UE transmits only the control
`signal, the control region can be assigned to transmit the
`control signal. In addition, When the UE transmits both the
`data and the control signal, the data region can be assigned to
`transmit the data and the control signal. In an exceptional
`case, even if only the control signal is transmitted, the control
`signal may be transmitted in a large amount or the control
`signal may be not suitable to be transmitted through the
`control region. In this case, a radio resource can be assigned
`to the data region to transmit the control signal.
`To maintain a single carrier property, the UE cannot simul
`taneously transmit the PUSCH and the PUCCH. This also
`means that one UE cannot simultaneously transmit tWo dif
`ferent PUCCHs in the same subframe.
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`TWo slots Within a subframe is frequency hopped. That is,
`a ?rst slot of the tWo slots is assigned to a ?rst frequency band,
`and a second slot thereof is assigned to a second frequency
`band. By using different subcarriers in the tWo slots, a fre
`quency diversity gain can be obtained.
`For clarity, it is assumed hereinafter that one slot consists of
`7 OFDM symbols, and thus one subframe including tWo slots
`consists of l 4 OFDM symbols in total. The number of OFDM
`symbols included in one subframe or the number of OFDM
`symbols included in one slot is for exemplary purposes only,
`and technical features of the present invention are not limited
`thereto.
`FIG. 5 shoWs a structure of an ACK/NACK channel. The
`ACK/NACK channel is a control channel through Which an
`ACK/NACK signal is transmitted to perform hybrid auto
`matic repeat request (HARQ) of doWnlink data. The ACK/
`NACK signal is a transmission and/ or reception con?rm sig
`nal for the doWnlink data.
`Referring to FIG. 5, among 7 OFDM symbols included in
`one slot, a reference signal (RS) is carried on three consecu
`tive OFDM symbols in the middle portion of the slot and the
`ACK/NACK signal is carried on the remaining four OFDM
`symbols. The RS is carried on three contiguous OFDM sym
`bols located in the middle portion of the slot. The location and
`the number of symbols used in the RS may vary depending on
`a control channel. Changes in the location and the number the
`symbols may result in changes in those symbols used in the
`ACK/NACK signal.
`When the control signal is transmitted Within an assigned
`band, frequency domain spreading and time domain spread
`ing are simultaneously used to increase the number of multi
`plexable UEs and the number of control channels. A fre
`quency domain sequence is used as a base sequence to spread
`the ACK/NACK signal on a frequency domain. A Zadoff-Chu
`(ZC) sequence is one of constant amplitude Zero auto-corre
`lation (CAZAC) sequences and can be used as the frequency
`domain sequence.
`A k-th element of a ZC sequence having an index of M can
`be expressed as shoWn:
`
`Math FIG. I
`
`' Mk k + 1
`C(k) : exp{—]ni()}, When N is odd number
`N
`
`th. I
`[Ma
`1
`
`J'nM/cz
`C(k) : exp —
`
`,
`, When N is even number
`
`Where N denotes a length of the ZC sequence. An index M
`is a natural number equal to or less than N. M and N are
`relatively prime to each other.
`Control channels can be identi?ed by using base sequences
`having different cyclic shift values. The number of available
`cyclic shifts may vary according to channel delay spread.
`After being subjected to frequency domain spreading, the
`ACK/NACK signal is subjected to IFFT processing and is
`then spread again in a time domain by using a time domain
`sequence. The ACK/NACK signal is spread using four
`orthogonal sequences W0, W1, W2, and W3 for four OFDM
`symbols. The RS is also spread using an orthogonal sequence
`having a length of 3. This is called orthogonal covering.
`To con?gure the ACK/NACK channel, the plurality of
`SC-FDMA symbols in the slot are divided into a ?rst set of
`SC-FDMA symbols (a SC-FDMA symbol set for the ACK/
`NACK signal) and a second set of SC-FDMA symbols (a
`SC-FDMA symbol set for a RS). The ACK/NACK signal is
`
`16
`
`

`

`US 7,852,883 B2
`
`7
`spread With each of ?rst frequency domain sequences Which
`is generated by cyclic shifts of a base sequence, and mapped
`to each SC-FDMA symbol in the ?rst set. Also, each of
`second frequency domain sequences Which is generated by
`cyclic shifts of the base sequence is mapped to each SC
`FDMA symbol in the second set. The mapped ACK/NACK
`signal is spread With a ?rst orthogonal sequence Which has the
`length equal to the number of SC-FDMA symbols in the ?rst
`set. Finally, the ACK/NACK channel is con?gured by spread
`ing the mapped second frequency domain sequences in the
`second set With a second orthogonal sequence Which has the
`length equal to the number of SC-FDMA symbols in the
`second set.
`NoW, a method of generating a scheduling request channel
`for transmitting a scheduling request (SR) Will be described.
`The SR is used When a UE request a BS to allocate an
`uplink radio resource. The SR is a sort of preliminary infor
`mation exchange for data exchange. In order for the UE to
`transmit uplink data to the BS, a radio resource needs to be
`allocated using the SR. When the UE transmits the SR, the BS
`allocates the radio resource for uplink data transmission and
`informs the UE of the radio resource allocation. The BS has to
`only recogniZe a presence/absence of the SR. Therefore, a
`positive transmission of the SR can be achieved With the
`presence of transmission of the SR, and a negative transmis
`sion of the SR can be achieved With the absence of transmis
`sion ofthe SR.
`A control channel such as anACK/NACK channel needs to
`be considered along With transmission of the SR. If the ACK/
`NACK channel and the scheduling request channel are sepa
`rately con?gured, the UE cannot transmit tWo channels in
`order to maintain the single carrier property. Therefore, there
`is a problem in that the UE cannot simultaneously transmit the
`SR and the ACK/NACK signal. This is because transmission
`is made by selecting one of the scheduling request channel
`and the ACK/NACK channel in order to maintain the single
`carrier property. HoWever, it is dif?cult to clearly distinguish
`priorities for selecting the SR and other control signals. For
`example, the ACK/NACK signal has a direct effect on a
`doWnlink throughput. In this case, transmission of the ACK/
`NACK signal may be delayed due to the SR, Which may cause
`deterioration in resource e?iciency.
`In addition, even if an additional control channel for simul
`taneously transmitting the SR and the ACK/NACK signal is
`de?ned, limited control channel resources may be Wasted as
`a result. This is because resources for a neW control channel
`needs to be reserved in addition to the scheduling request
`channel and the ACK/NACK channel.
`Therefore, there is a need for a method Whereby the UE can
`simultaneously transmit the SR and the ACK/NACK signal in
`an effective manner.
`Hereinafter, a con?guration of an effective scheduling
`request channel for transmitting a SR in an ACK/NACK
`channel con?gured using time-frequency domain spreading
`Will be described. To simultaneously transmit the SR and
`other control signals, the channel has to be con?gured to
`satisfy the folloWing requirements.
`(1) Compatibility With the ACK/NACK channel (or other
`control channels) is possible.
`(2) The same channel structure is used even When only the
`SR is transmitted.
`(3) Capability of the existingACK/NACK channel is main
`tained When only the ACK/NACK signal is transmitted.
`(4) Channel capability is maximiZed When the SR and the
`ACK/NACK signal is simultaneously transmitted.
`
`40
`
`45
`
`20
`
`30
`
`35
`
`50
`
`55
`
`60
`
`65
`
`8
`(5) The same channel con?guration is achieved irrespec
`tive of Whether the ACK/NACK signal and the SR are simul
`taneously transmitted.
`(6) Con?guration of the ACK/NACK channel and con?gu
`ration of the scheduling request channel are ?exible in an
`assigned time-frequency resource.
`(7) Flexibility of sequence allocation is increased When a
`dedicated scheduling request channel is con?gured through
`sequence allocation.
`(8) Transmission of the ACK/NACK signal and the SR is
`possible When

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