as) United States
`a2) Patent Application Publication co) Pub. No.: US 2006/0262871 Al
`
` Choetal. (43) Pub. Date: Nov. 23, 2006
`
`
`US 20060262871A1
`
`(54) METHOD AND APPARATUS FOR
`MULTIPLEXING DATA AND CONTROL
`
`(30)
`
`Foreign Application Priority Data
`
`INFORMATION IN WIRELESS
`COMMUNICATION SYSTEMS BASED ON
`FREQUENCY DIVISION MULTIPLE ACCESS
`
`May 3, 2005
`
`(KR)wneesesesssssssecsseeneeeseerses 2005-37294
`
`Publication Classification
`
`(76)
`
`Inventors: Joon-Young Cho, Suwon-si (KR);
`Ju-Ho Lee, Suwon-si (KR);
`Hwan-Joon Kwon, Suwon-si (KR);
`Yun-Ok Cho, Suwon-si (KR)
`
`Correspondence Address:
`ROYLANCE, ABRAMS, BERDO &
`GOODMAN,L.L.P.
`1300 19TH STREET,N.W.
`SUITE 600
`WASHINGTON,, DC 20036 (US)
`
`(21) Appl. No.:
`
`11/416,393
`
`(22)
`
`Filed:
`
`May3, 2006
`
`(51)
`
`Int. Cl.
`(2006.01)
`HO4K 1/10
`(52) US. Ce ecceeesecssncesecsssscecesencesenessscecsenceseeneaee 375/260
`
`(57)
`
`ABSTRACT
`
`An apparatus for transmitting data in a frequency division
`multiple access based communication system is disclosed.
`The apparatus includes a symbol block generator for gen-
`erating a symbol block in a predetermined symbol block
`period within one TTI when control
`information to be
`transmitted exists in the TTI, an FFT unit for performing
`FFT on the symbol block, and an IFFT unit for performing
`IFFT on signals output from the FFT unit and then trans-
`mitting the signals. The symbol block includes the control
`information and data to be transmitted. The TTI includes
`multiple symbol block periods.
`
`(314)
`
`BLOCK
`
`SYMBOL
`
`7 A
`ON
`|CS|oATA DATA [DATA RSNSNDATA pata \WYat
`
`Seo
`
`BLOCK
`DURATION
`(302)
`
`e800) (310)
`
`IFOMA
`Or
`
`mapaing
`
`(312)
`
`APPLE 1005
`
`APPLE 1005
`
`

`

`Patent Application Publication Nov. 23, 2006 Sheet 1 of 9
`
`US 2006/0262871 Al
`
`OF CP
`
`PARALLEL-
`TO-SERIAL|»ADDITION
`CONVERSION
`
`FIG.1
`(CONVENTIONAL ART)
`
`

`

`Patent Application Publication Nov. 23, 2006 Sheet 2 of 9
`
`US 2006/0262871 Al
`
`(206)
`
`TX
`SYMBOLS
`
`OF CP
`
`PARALLEL-
`TO-SERIAL
`CONVERSION
`
`|_-»/ADDITION
`
`FIG.2
`|
`(CONVENTIONAL ART)
`
`

`

`Patent Application Publication Nov. 23, 2006 Sheet 3 of 9
`
`US 2006/0262871 A1
`
`Guiddeu
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`(cle)40018
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`TOBIAS
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`

`

`Patent Application Publication Nov. 23, 2006 Sheet 4 of 9
`
`US 2006/0262871 Al
`
`
`
`(400)
`
`FEMAPPA
`
`(404)
`
`SeasA
`
`
`
`
`
`DATA
`(402)|(yariABLe FORMAT)
`
`

`

`Patent Application Publication Nov. 23, 2006 Sheet 5 of 9
`
`US 2006/0262871 A1
`
`
`
`(71S)
`
`
`
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`(yzq)ONT(00S)IOBLNOD
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`(705)(208)
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`"ALIINWADWLC“3W3HOSNIdd
`onbiOai“(N32IS)EESN03
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`

`

`Patent Application Publication Nov. 23, 2006 Sheet 6 of 9
`
`US 2006/0262871 Al
`
`(614) YMBO BLOCKDURATION (604)
`
`DATA
`
`Yj
`
` FIG.6
`yyis
`CONTEGE
`TT(602) (600)
`
`
`SOMTRONSONTRON
`
`DATA|DATA
`
`

`

`Patent Application Publication Nov. 23, 2006 Sheet 7 of 9
`
`US 2006/0262871 Al
`
`

`

`Patent Application Publication Nov. 23, 2006 Sheet 8 of 9
`
`US 2006/0262871 Al
`
`START
`
`EXTRACT PILOT FROM FFT OUTPUT &
`PERFORM CHANNEL ESTIMATION
`
`800
`
`~ CHANNEL COMPENSATION FOR SYMBOL
`BLOCK PERIOD INCLUDING BOTH DATA &
`CONTROL INFO OR ONLY DATA
`
`L802
`
`
`
`
`EXTRACT/DEMODULATE/DECODE CONTROL INFO
`FROM IFFT OUTPUT & CONVERTIT TO CONTROL
`INFO INCLUDING MODULATION & CODING
`SCHEMES APPLIED TO DATA & HARQ INFO
`
`
` 804
`
`DEMODULATE & DECODE IFFT OUTPUT CORRES-
`PONDING TO SYMBOL BLOCK PERIOD INCLUDING}
`BOTH DATA & CONTROLINFO OR ONLY DATA
`
`806
`
`FIG.8
`
`

`

`Patent Application Publication Nov. 23, 2006 Sheet 9 of 9
`
`US 2006/0262871 Al
`
`START
`
`:
`
`GENERATE FRAME WITHIN TTI BY MULT]
`PLEXING DATA, CONTROLINFO & PILOT
`
`gy
`
`PERFORM FFT ON SIGNAL BLOCKS
`WITHIN EACH SYMBOL BLOCK PERIOD[~992
`
`MAP FFT OUTPUT TO IFFT OUTPUT ACCORDING
`TO IFDMA OR LFDMA RULE & PERFORM IFFT[~904
`
`ATTACH CP TO IFFT OUTPUT &
`TRANSMIT IT
`
`906
`
`~ END
`
`FIG.Y
`
`

`

`US 2006/0262871 Al
`
`Nov. 23, 2006
`
`METHOD AND APPARATUS FOR MULTIPLEXING
`DATA AND CONTROL INFORMATION IN
`WIRELESS COMMUNICATION SYSTEMS BASED
`ON FREQUENCY DIVISION MULTIPLE ACCESS
`
`PRIORITY
`
`[0001] This application claimsthe benefit under 35 U.S.C.
`§119(a) of a Korean Patent Application filed in the Korean
`Industrial Property Office on May 3, 2005 and assigned
`Serial No. 2005-37294, the entire disclosure of which is
`hereby incorporated by reference.
`
`BACKGROUND OF THE INVENTION
`
`[0002]
`
`1. Field of the Invention
`
`[0003] The present invention relates to a wireless com-
`munication system based on frequency division multiple
`access. Moreparticularly, the present invention relates to a
`method and apparatus for multiplexing and transmitting data
`and control information in a wireless communication system
`based on frequency division multiple access.
`
`[0004]
`
`2. Description of the Related Art
`
`[0005] Recent developments in broadcasting and mobile
`communication systems technology hasled to the wide use
`of an Orthogonal Frequency Division Multiplexing (OFDM)
`transmission scheme. The OFDM scheme eliminates the
`
`interference between multi-path signals, which is frequently
`found in wireless communication channels. Also, the OFDM
`scheme guarantees the orthogonality between multiple
`access users and facilitates an efficient use of resources.
`Therefore, the OFDM scheme is available for high speed
`data transmission and broadband systems more than the
`conventional Code Division Multiple Access
`(CDMA)
`scheme. However,
`the OFDM scheme is a multi-carrier
`transmission scheme, in which transmission data is distrib-
`uted to multiple sub-carriers and is then transmitted in
`parallel. This causes the OFDM scheme to increase the
`Peak-to-Average Power Ratio (PAPR)of the transmission
`signals.
`
`[0006] A large PAPR causesdistortion of output signals in
`a Radio Frequency (RF) power amplifier of a transmitter.
`Therefore, in order to solve such a problem, the transmitter
`requires power back-off to reduce the input power to the
`amplifier. Therefore, when the OFDM schemeis applied to
`the uplink of a mobile communication system, a terminal
`must perform the power back-off for the transmission sig-
`nals, which results in the reduction of the cell coverage.
`
`Interleaved Frequency Division Multiple Access
`[0007]
`(IFDMA)is being actively researched as a solution to solve
`the PAPR problem of the OFDM technology. The IFDMA
`guarantees the orthogonality between the multiple access
`users like the OFDM andis a technology based on a single
`sub-carrier, which shows a very low PAPRof transmission
`signals. Applying the IFDMA to a mobile communication
`system reduces the problem of cell coverage reduction due
`to the PAPRincrease.
`
`FIG.1 illustrates a structure of a typical IDMA
`[0008]
`transmitter.
`
`[0009] Although the structure shown in FIG.1 uses a Fast
`Fourier Transform (FFT) unit 104 and an Inverse Fast
`Fourier Transform (IFFT) unit 106, exemplary embodiments
`
`limited to the shown
`invention are not
`of the present
`structure and can be implemented by additional structures.
`The implementation that uses the FFT unit 104 and the IFFT
`unit 106 is advantageous because it facilitates an easy
`change of IFDMA system parameters without a high hard-
`ware complexity.
`
`[0010] The OFDM and the IFDMA mayhavethe follow-
`ing differences in the aspect of transmitter structure. In
`addition to the IFFT unit 106 which is used for multi-carrier
`
`transmission in the OFDM transmitter, the IFDMA trans-
`mitter includes the FFT unit 104 located before the IFFT unit
`
`106. Therefore, the transmission modulation (TX) symbols
`100 in FIG.1 are input to the FFT unit 104 block by block,
`each of which includes M number of transmission modula-
`
`tion symbols. The block is referred to as “symbol block,”
`and the period at which the symbolblock is input to the FFT
`unit is referred to as “symbol block period.” The signals
`output from the FFT unit 104 are input to the IFFT unit 106
`at equal intervals, so that the IFDMAtransmission signal
`elements are transmitted in the frequency domain by sub-
`carriers of equal intervals. In this process, it is usual for the
`input/output size N of the IFFT unit 106 to have a larger
`value than that of the input/output size M of the FFT unit
`104. In the OFDM transmitter,
`the transmission symbol
`blocks 100 are directly input to the IFFT unit 106 without
`passing through the FFT unit 104 andare then transmitted by
`multiple sub-carriers, thereby generating a PAPR with a
`large value.
`
`In the IFDMA transmitter, the transmission sym-
`[0011]
`bols are pre-processed by the FFT unit 104 before being
`processed by the IFFT unit 106. This occurs even though the
`transmission symbols are finally processed by the IFFT unit
`106 before being transmitted by multiple carriers. The
`pre-processing of the transmission symbols makes it pos-
`sible, due to the counterbalancing between the FFT unit 104
`and the IFFT unit 106, to have an effect similar to that which
`occurs when the output signals of the IFFT unit 106 are
`transmitted by a single sub-carrier, thereby achieving a low
`PAPR.Finally, the outputs of the IFFT unit 106 are con-
`verted to a serial stream by a Parallel-to-Serial Converter
`(PSC) 102. Before the serial stream is then transmitted, a
`Cyclic Prefix (CP) or guard interval is attached to theserial
`stream as it is in the OFDMsystem,to prevent interference
`between multi-path channel signal elements.
`
`[0012] FIG. 2 illustrates a structure of a transmitter based
`on a Localized Frequency Division Multiple Access
`(LFDMA)technique, which is similar to the IFDMA tech-
`nique. The LFDMA technique also guarantees the orthogo-
`nality between multiple access users,
`is based on single
`carrier transmission, and can achieve a PAPR lowerthanthat
`of the OFDM. Asillustrated in FIGS. 1 and 2, the difference
`between the LFDMAand the IFDMA in the view oftrans-
`
`mitter structure is that the outputs of the FFT unit 204 turn
`into inputs to the IFFT unit 206, which have sequential
`indexes following the last index of the FFT unit 204. In the
`frequency domain, the LFDMA signals occupy the band
`constituted by adjacent sub-carriers used when the outputs
`of the FFT unit 204 are mapped into the inputs of the IFFT
`unit 206. In other words,
`in the frequency domain,
`the
`IFDMA signals occupy the sub-carrier bands (sub-bands)
`distributed at an equal interval, and the LFDMA signals
`occupy the sub-band constituted by adjacent sub-carriers.
`
`

`

`US 2006/0262871 Al
`
`Nov. 23, 2006
`
`In order to apply the IFDMA and LFDMA based
`[0013]
`systemsto a broadcasting or mobile communication system,
`it is necessary to transmit data and to control information
`and a pilot signal for demodulation and decoding of the data
`in a receiver. The pilot signal has a guaranteed pattern
`between a transmitter and a receiver. Therefore, when a
`received signal has a distortion due to a wireless fading
`channel, the receiver can estimate and eliminate, based on
`the pilot signal, the distortion in the received signal due to
`the wireless
`fading channel. The control
`information
`includes a modulation scheme applied to the transmitted
`data, a channel coding scheme,a data block size, and Hybrid
`Automatic Repeat Request
`(HARQ)-related information
`such as a serve packet ID. By receiving the control infor-
`mation, the receiver can understand the information applied
`to the transmitted data to perform various operations includ-
`ing demodulation and decoding of the received data.
`
`[0014] According to the CDMAtechnique widely applied
`to current mobile communication systems, the data, control
`information, and pilot signal are transmitted by using dif-
`ferent channelization codes. This allows the receiver to
`separate and detect the signals without interference. Accord-
`ing to the OFDM technique, the data, control information,
`and pilot signal are transmitted by different sub-carriers or
`after being temporally divided.
`
`Since the control informationis not a large quantity
`[0015]
`of information capable of totally occupying one timeslot,
`application of the time division-based multiplexing scheme
`may result in an unnecessary waste of resources. When the
`control information is transmitted by a separate sub-carrier
`different from that which carries the data as it does in the
`
`is problematic in that the transmitted
`it
`OFDM scheme,
`signal has an increased PAPR.
`
`there is a need for an improved
`[0016] Accordingly,
`method and apparatus for multiplexing data and control
`information to lower a PAPRof a transmitted signal and to
`facilitate resource efficiency in an IFDMA or LFDMA-based
`communication system.
`SUMMARY OF THE INVENTION
`
`[0017] An aspect of exemplary embodiments of the
`present invention is to address at least the above problems
`and/or disadvantages andto provide at least the advantages
`described below. Accordingly, an aspect of exemplary
`embodiments of the present invention is to provide a method
`and an apparatus for multiplexing data and control informa-
`tion to lower a PAPRofa transmitted signal and to facilitate
`the efficient use of resources in anJIFDMA or LFDMA-based
`
`communication system.
`
`Itis another object of an exemplary embodiment of
`[0018]
`the present invention to provide a method and an apparatus
`for multiplexing data and control information at an FFT
`input side within one FFT block period in an IFDMAor
`LFDMA-based communication system.
`
`It is also another object of an exemplary embodi-
`[0019]
`ment of the present invention to provide a method and an
`apparatus for multiplexing data by distributing control infor-
`mation in each symbolblock period within a Transmission
`Time Interval (TTD in an IFDMA or LFDMA-based com-
`munication system.
`
`In order to accomplish this object, an apparatus for
`[0020]
`transmitting data in a frequency division multiple access
`
`based communication system is provided. The apparatus
`includes a symbol block generator, a Fast Fourier Transform
`(FFT) unit, and an Inverse Fast Fourier Transform (IFFT)
`unit. The symbol block generator generates a symbol block
`in a predetermined symbol block period within one Trans-
`mission Time Interval (TTI) when control information to be
`transmitted exists in the TTI. Also,
`the symbol block
`includes the control information and data to be transmitted
`and the TTI includes multiple symbol block periods. A Fast
`Fourier Transform (FFT) unit performs FFT on the symbol
`block and an Inverse Fast Fourier Transform (IFFT) unit
`performs IFFT on signals output from the FFT unit and then
`transmits the signals.
`
`In accordance with another aspect of an exemplary
`[0021]
`embodiment of the present invention, a method for trans-
`mitting data in a frequency division multiple access based
`communication system is provided. A symbol block is
`generated in a predetermined symbol block period within
`one Transmission Time Interval (TTI) when control infor-
`mation to be transmitted exists in the TTI. The symbol block
`includes the control information and data to be transmitted
`and the TTI includes multiple symbol block periods. Fast
`Fourier Transform (FFT) is performed on the symbolblock,
`Inverse Fast Fourier Transform (IFFT) is performed on the
`FFTed signals, and then the IFFTed signals are transmitted.
`
`In accordance with another aspect of an exemplary
`[0022]
`embodiment of the present
`invention, an apparatus for
`receiving data in a frequency division multiple access based
`communication system is provided. The apparatus includes
`a Fast Fourier Transform (FFT) unit, an Inverse Fast Fourier
`Transform (IFFT), a control information demodulator/de-
`coder, and a data demodulator/decoder. The FFT unit
`receives signals received during one symbol block period
`and performs FFT on the signals. The IFFT unit performs
`IFFT on the signals output from the FFT unit,
`thereby
`restoring symbol blocks. When the symbolblock period is a
`predetermined symbol block period in which data and
`control information are multiplexed, the control information
`demodulator/decoder, receives modulation symbols corre-
`sponding to predetermined IFFT output indexes from among
`the symbol blocks and demodulates and decodes the modu-
`lation symbols, thereby outputting control information. The
`data demodulator/decoder receives modulation symbols cor-
`responding to the other IFFT output indexes except for
`indexes corresponding to the control
`information from
`among the symbol blocks by using the control information,
`demodulates and decodes the received modulation symbols,
`and then outputs the data.
`
`[0023] According to another aspect of an exemplary
`embodimentof the present invention, a methodfor receiving
`data in a frequency division multiple access based commu-
`nication system is provided. The method includes the steps
`of: receiving signals recerved during one symbol block
`period and performing Fast Fourier Transform (FFT) on the
`signals by an FFT unit; restoring symbol blocks from the
`FFTed signals by an Inverse Fast Fourier Transform (IFFT)
`unit; when the symbol block period is a predetermined
`symbol block period in which data and control information
`are multiplexed, receiving modulation symbols correspond-
`ing to predetermined IFFT output indexes from among the
`symbol blocks from the IFFT unit and demodulating and
`decoding the modulation symbols, thereby outputting con-
`trol information; and receiving modulation symbols corre-
`
`

`

`US 2006/0262871 Al
`
`Nov. 23, 2006
`
`spondingto the other IFFT output indexes except for indexes
`corresponding to the control information from among the
`symbol blocks from the IFFT unit by using the control
`information, demodulating and decoding the received modu-
`lation symbols, and then outputting the data.
`
`[0024] Other objects, advantages, and salient features of
`the invention will become apparent to those skilled in the art
`from the following detailed description, which,
`taken in
`conjunction with the annexed drawings, discloses exemplary
`embodiments of the invention.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0025] The above and other exemplary objects, features
`and advantages of certain exemplary embodiments of the
`present invention will be more apparent from the following
`detailed description taken in conjunction with the accom-
`panying drawings, in which:
`
`[0026] FIG. 1 illustrates a structure of a conventional
`IFDMAtransmitter;
`
`[0027] FIG. 2 illustrates a structure of a conventional
`LFDMaA transmitter;
`
`FIG.3 illustrates an apparatus for multiplexing and
`[0028]
`transmitting data, control information, and a pilot signal
`according to a first exemplary embodiment of the present
`invention;
`
`FIG.4 illustrates the FFT mapping in the symbol
`[0029]
`block period in which the control information and the data
`are multiplexed according to the first exemplary embodi-
`ment of the present invention;
`
`FIG.5 illustrates a structure of a receiver accord-
`[0030]
`ing to the first exemplary embodimentof the present inven-
`tion;
`
`FIG.6 illustrates a method for multiplexing con-
`[0031]
`trol information and data according to a second exemplary
`embodimentof the present invention;
`
`[0032] FIG. 7 illustrates a structure for mapping IFFT
`outputs to the control information demodulator/decoder and
`the data demodulator/decoder in the receiver according to
`the first or second exemplary embodiment of the present
`invention;
`
`[0033] FIG. 8 is a flowchart for illustrating the operation
`of the receiver according to a first exemplary embodiment of
`the present invention; and
`
`[0034] FIG. 9 is a flowchart showing an operation of a
`transmitter according to an exemplary embodiment of the
`present invention.
`
`[0035] Throughout the drawings, the same drawing refer-
`ence numerals will be understood to refer to the same
`elements, features, and structures.
`
`DETAILED DESCRIPTION OF EXEMPLARY
`EMBODIMENTS
`
`[0036] The matters defined in the description such as a
`detailed construction and elements are provided to assist in
`a comprehensive understanding of the embodiments of the
`invention. Accordingly, those of ordinary skill in the art will
`recognize that various changes and modifications of the
`embodiments described herein can be made without depart-
`
`ing from the scope andspirit of the invention. Also, descrip-
`tions of well-known functions and constructions are omitted
`
`for clarity and conciseness.
`
`[0037] An exemplary embodiment of the present inven-
`tion proposes a method of multiplexing data and control
`information in at
`least one symbol block from among
`multiple symbol blocks included in one TTI and simulta-
`neously transmitting the multiplexed data and control infor-
`mation. The method of multiplexing and simultaneoustrans-
`mission can achieve a lower PAPR andresults in a more
`efficient use of resources comparedto the existing methods.
`The control
`information includes a modulation scheme
`applied to transmission data, a channel coding scheme, a
`data block size, and a Hybrid Automatic Repeat Request
`(HARQ)-related information such as a sub-packet ID. This
`can be included together with control information, such as
`Channel Quality Indicator (CQD or ACK/NACK.
`
`FIG.3 illustrates an apparatus for multiplexing and
`[0038]
`transmitting data, control information, and a pilot signal
`according to a first exemplary embodiment of the present
`invention.
`
`[0039] As shownin FIG.3, a symbol block generator 304
`of a transmitter generates a symbol block by multiplexing
`data, control information, or pilot signals to be transmitted
`for each symbol block period. The exemplary embodiment
`of FIG.3 illustrates one Transmission Time Interval (TTT)
`which includes eight symbol block periods.
`
`[0040] The symbol block generator 304 determines
`whether control information exists within the current TTI
`300. When control information exists within the current TTI
`
`300, the symbol block generator 304 generates a symbol
`block including the control information and data in a pre-
`determined symbol block period 302 within the TTI 300.
`The symbol block generator 304 generates symbol blocks
`which include data or a pilot signal without control infor-
`mation in other symbol block periods. Each symbol block
`includes M number of symbols, which are mapped to M
`numberof inputs of the FFT unit 310.
`
`In FIG. 3, the IFDMA or LFDMA transmission
`[0041]
`technique can be seen as the output signals of the FFT unit
`310 by multi-carriers by using the IFFT unit 314. Therefore,
`N numberof outputs from the IFFT unit 314 are converted
`to a serial stream by the PSC 102 as shown in FIG. 1, which
`is then transmitted with a CP attached thereto. At this time,
`each period in which the N outputs are generated corre-
`sponds to the symbol block period.
`
`[0042] Therefore, each of the eight symbol blocks in the
`TTI 300 is input to the FFT unit 310 at a corresponding
`symbol block period. Each of the symbol blocks is an FFT
`input block input through all input taps of the FFT unit 310
`and has the samesize as the tap size M of the FFT unit 310.
`Further, the M outputs of the FFT unit 310 are mappedto the
`inputs of the IFFT unit 314 according to the mapping rule
`corresponding to the IFDMA or LFDMA technique to be
`applied which is similar to the techniques applied in FIGS.
`1 and 2. Finally,
`the outputs of the IFFT unit 314 are
`converted to a serial stream, which is then transmitted
`together with a CP attached thereto.
`
`[0043] FIG. 9 is a flowchart illustrating an operation of a
`transmitter according to an exemplary embodiment of the
`present invention.
`
`

`

`US 2006/0262871 Al
`
`Nov. 23, 2006
`
`In step 900, the transmitter generates frames in
`[0044]
`TTI, that is, transmission data, by multiplexing data, control
`information, and pilot signals to be transmitted. When there
`is control information to be transmitted during one TTI, the
`transmitter inserts the control information into a symbol
`block predetermined within the TTI, and inserts data into a
`remaining portion of the symbol block. The pilot signal is
`included in and transmitted by one symbol block, and the
`data is included in a portion of the symbol block including
`the control signal and other symbol blocks except for the
`symbol block including the pilot signal. In step 902, the
`transmitter performs FFT on a symbol block of a corre-
`sponding period at each symbol block period.
`
`In step 904, the outputs of the FFT unit are mapped
`[0045]
`to the inputs of the IFFT unit according to the mapping rule
`corresponding to the applied IFDMA or LFDMA technique
`to be applied, and IFFT is then performed. In step 906, the
`transmitter attaches a CP to the output of the IFFT unit and
`then transmits it.
`
`[0046] As described above, the method proposed by the
`first exemplary embodimentof the present invention is to
`multiplex the data 306 and the control information 304 at the
`FFT input side during one symbol block period. The pilot
`signal 308 is transmitted during one entire symbol block
`period. This method of transmissionis different from that of
`the data 306 and the control information 304. In the case of
`IFDMA or LFDMAtransmission, when the pilot signal 308
`is multiplexed together with data within the same symbol
`block period, it is difficult to perform channel estimation and
`normally demodulate the received data and control infor-
`mation. However, as noted from the following description
`regarding the operation of a receiver, even when the control
`information 304 is multiplexed together with the data 306
`within one symbolblock period, it is possible to demodulate
`and decode the received data 306 and the control informa-
`tion 304.
`
`[0047] The method for multiplexing data 306, the control
`information 304, and the pilot signal 308 is applicable even
`to an JIFDMA or LFDMAtransmitter which is not based on
`the FFT and IFFT.
`
`[0048] Multiplexing the data and control information in
`one IFDMA symbol stream as shown in FIG. 3 makes it
`possible to obtain a lower PAPR, in comparison with the
`case data and control information which are divided in the
`frequency domain andare then transmitted according to the
`IFDMA or LFDMA scheme by using different sub-carrier
`bands as in an OFDM system. Further, the method as shown
`in FIG, 3 facilitates a more efficient use of resources, in
`comparison with the case of temporally multiplexing the
`data and the control information and then transmitting them
`in different symbol block periods by IFDMA or LFDMA.
`This results from the fact
`that
`the control
`information
`
`usually has a small volume, and allocation of one symbol
`block period to the transmission of the control information
`would result in allocation of an unnecessarily large quantity
`of resources to the transmission of the control information
`
`and cause a reduction of many resources which could
`otherwise be used for the data transmission. This problem
`becomes more severe whenit is necessary to transmit a large
`quantity of data at a high datarate.
`
`[0049] Hereinafter, a description will be given regarding
`the frame format of a transmission IFDMA or LFDMA
`
`signal for normal demodulation and decoding of data by a
`receiver when the data and control information are multi-
`
`plexed as described above. According to the quantity of data
`to be transmitted or the condition of a transmitted radio
`
`channel, different modulation schemes and coding schemes
`maybeapplied to the data transmission. When the HARQ
`technique is applied, different HARQ control information
`may be transmitted according to the retransmission situa-
`tions. Therefore, normal demodulation of data is possible
`only whenthe receiver has recognized the control informa-
`tion by demodulating and decoding the control information.
`
`[0050] The transmission format of the control information
`should be defined to be fixed to a specific transmission
`formator as one format used between the transmitter and the
`
`receiver at the time of radio link setup to facilitate normal
`demodulation of the control information for the user. The
`
`receiver can normally demodulate and decode the control
`information when the control information is mapped and
`transmitted with an always fixed modulation scheme and
`channel coding scheme,fixed numberof control information
`bits, and fixed time slots and FFT inputs. For example, the
`exemplary embodiment of FIG. 3 illustrates the control
`information convolutionally encoded with a coding rate of
`1/3 and then transmitted according to the QPSK modulation
`scheme, and includes L number of modulation symbols. The
`L modulation symbols are transmitted after being applied to
`the FFT inputs with input indexes of 0~(L-1) in the second
`symbol block period within the TTI. Then, the receiver can
`demodulate and decode the control information by using the
`transmission format of the control information, which is
`already recognized by the receiver. If the control is not
`transmitted with a fixed format, the receiver must try to
`detect the format for various possible formats by applying a
`blind format detection method.
`
`FIG.4 illustrates the FFT mapping in the symbol
`[0051]
`block period in which the control information and the data
`are multiplexed according to the first exemplary embodi-
`ment of the present invention. Referring to FIG. 4, the
`control information 400, including L modulation symbols, is
`applied to the inputs of the FFT unit 404 with input indexes
`of 0~(L-1), and the data is applied to the other FFT inputs,
`such as, the FFT inputs with the input indexes of 0~(L-1).
`It should be noted that the locations to which the modulation
`symbols of the control information 400 are mappedare not
`limited to the upper indexes of 0~(L-1). The control infor-
`mation may be mapped to any L numberof taps known in
`advanceto the transmitter and the receiver from among the
`M input taps of the FFT unit.
`
`FIG.5 illustrates a structure of a receiver accord-
`[0052]
`ing to the first exemplary embodimentof the present inven-
`tion.
`
`[0053] Referring to FIG.5, the receiverfirst eliminates the
`CP from the received signal, performs FFT by the FFT unit
`502, extracts the pilot signal from the output of the FFT unit
`502, and then performs channelestimation. For example, the
`FFT unit 502 of the receiver converts the received signal
`input to the FFT unit 502 to a frequency domain signal,
`corresponding to the IFFT unit 314 shown in FIG. 3. When
`the output from the FFT unit 502 corresponds to the pilot
`510, the output of the FFT unit 502 is input to the channel
`estimator 504. When the symbol block period in which the
`output of the FFT 502 occurs is a predetermined pilot period
`
`

`

`US 2006/0262871 Al
`
`Nov. 23, 2006
`
`in one TTI as shownin FIG.3, the output of the FFT unit
`502 is considered as the pilot 510.
`
`[0054] The channel estimator 504 generates channel esti-
`mation information 512 by estimating the channel condition
`from the pilot 510 and transfers the generated channel
`estimation information 512 to the channel compensation
`block 524 so that the IFFT unit 506 can demodulate the data
`and control information. Thereafter, the output from the FFT
`unit 502 is channel-compensated by using the channel
`estimation information 512 by the channel compensation
`block 524. The extraction of the pilot 510 by the channel
`estimator 504 and the channel compensation by the channel
`compensation block 524 may be performed by the output
`side of the IFFT unit 506.
`
`[0055] The channel-compensated signal 526 is input to the
`IFFT unit 506 according to the IIFDMA or LFDMA mapping
`rule applied in the transmitter, and is then subjected to the
`demodulation and decoding.
`
`In the case of the symbol block period including
`[0056]
`the control information and data, since the control informa-
`tion has been transmitted after being applied to the input
`indexes of 0~(L-1) of the FFT unit 404, the IFFT unit 506
`of FIG.5 applies the outputs 520 with the output indexes of
`0~(L-1) to the control
`information demodulator/decoder
`508, so that it is possible to extract the control information.
`Further, in the case of data, since pure data may sometimes
`be transmitted in one symbol block period,all the outputs of
`the IFFT unit 506, such as, the outputs 518 with the output
`indexes of 0~(M-1) are applied to the data demodulator/
`decoder 522. When the modulation and coding schemes
`used by the transmitted data for data transmission,
`the
`quantity of data, the HARQ control information 516, etc.
`have been transferred to the data demodulator/decoder 522
`
`by the demodulation and decoding of the control informa-
`tion in the symbolblock period correspondingto the control
`information, the decoded datais finally output from the data
`demodulator/decoder 522.
`
`[0057] FIG. 8 is a flowchart for illustrating the operation
`of the receiver according to a first exemplary embodiment of
`the present invention.
`
`In step 800, the receiver eliminates the CP from the
`[0058]
`received signal, performs FFT, extracts the pilot from the
`FFT output, and then performs channel estimation. In step
`802, when the FFT output corresponds to a symbol block
`period including data and control in