(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2006/0098568 A1
`Oh et al.
`(43) Pub. Date:
`May 11, 2006
`
`US 20060098568A1
`
`(54) METHOD FOR SUPPORTING VARIOUS
`MULT-ANTENNASCHEMES IN BWA
`SYSTEM USING MULTIPLE ANTENNAS
`(75) Inventors: Jeong-Tae Oh, Yongin-si (KR); Won-Il
`Roh, Yongin-si (KR); Kyun-Byoung
`Ko, Hwaseong-si (KR); Jae-Ho Jeon,
`Seongnam-si (KR); Sung-Ryul Yun,
`Suwon-si (KR); Hong-Sil Jeong,
`Suwon-si (KR); Chan-Byoung Chae,
`Seoul (KR); Seung-Joo Maeng,
`Seongnam-si (KR)
`
`Correspondence Address:
`DILWORTH & BARRESE, LLP
`333 EARLE OVINGTON BLVD.
`UNIONDALE, NY 11553 (US)
`
`(73) Assignee: SAMSUNG ELECTRONICS CO.,
`LTD., Suwon-si (KR)
`
`(21) Appl. No.:
`
`11/268,893
`
`(22) Filed:
`
`Nov. 8, 2005
`
`(30)
`
`Foreign Application Priority Data
`
`Nov. 9, 2004 (KR)....................................... 91120/2004
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`H04 II/00
`(52) U.S. Cl. .............................................................. 370/2O6
`(57)
`ABSTRACT
`Disclosed is a method for using various multiple antenna
`schemes in a baseband wireless access system is provided.
`According to the method, a downlink MAP message is
`constructed in order to Support various multiple antenna
`schemes based on a multiple-input multiple output (MIMO),
`which is one of the multiple antenna Schemes, so that
`compatibility with exiting MIMO technology having no
`MIMO feedback can be achieved and overhead occurring in
`transmission of an MAP information element can be
`reduced. Further, it is possible to efficiently support spatial
`multiplexing technology capable of transmitting multiple
`layers having different modulation and coding in a MIMO
`system.
`
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`Precoding
`matrix
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`

`

`Patent Application Publication May 11, 2006 Sheet 1 of 3
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`US 2006/0098568 A1
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`Patent Application Publication May 11, 2006 Sheet 2 of 3
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`US 2006/0098568 A1
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`D
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`Patent Application Publication May 11, 2006 Sheet 3 of 3
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`US 2006/0098568 A1
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`

`

`US 2006/0098568 A1
`
`May 11, 2006
`
`METHOD FOR SUPPORTNG VARIOUS
`MULT-ANTENNASCHEMES IN BWA SYSTEM
`USING MULTIPLE ANTENNAS
`
`PRIORITY
`0001. This application claims priority to an application
`entitled “Method for Supporting Various Multi-antenna
`Schemes in BWA System Using Multiple Antenna' filed in
`the Korean Intellectual Property Office on Nov. 9, 2004 and
`assigned Serial No. 2004-91120, the contents of which are
`incorporated herein by reference.
`
`BACKGROUND OF THE INVENTION
`0002) 1. Field of the Invention
`0003. The present invention relates to a Broadband Wire
`less Access (BWA) system, and more particularly to a
`method for Supporting various multiple antenna Schemes in
`a system using an Orthogonal Frequency Division Multiple
`Access (OFDMA) scheme.
`0004 2. Description of the Related Art
`0005. In the current wireless mobile communication sys
`tem, extensive research is being conducted into a high
`quality multimedia service capable of transmitting mass
`storage data at a high speed. Different from wire channel
`environments, wireless channel environments are subject to
`a distortion of the actual transmission signals due to various
`factors such as multi-path interference, shadowing, wave
`attenuation, time-varying noise and interference. Fading due
`to the multi-path interference is closely related to the mobil
`ity of a reflector or a user terminal. Accordingly, the actual
`transmission signals are mixed with interference signals and
`mixed signals are received. Because the received signals
`already represent a serious distortion of the actual transmis
`sion signals, the entire performance of a mobile communi
`cation system may deteriorate.
`0006 Fading may also distort the amplitude and phase of
`the received signals, and may become a main factor that
`disrupts the high speed data communication in wireless
`channel environments. Therefore, extensive research is
`being conducted in order to solve the fading problem. In
`order to transmit data at a high speed in a mobile commu
`nication system, it is necessary to minimize loss and any
`user-by-user interference resulting from the characteristics
`of a mobile communication channel. One of the technolo
`gies proposed in order to solve the afore-described problems
`is a Multiple Input Multiple Output (MIMO) technology.
`0007. The MIMO technology may be classified accord
`ing to the data transmission schemes used and whether the
`channel information is fedback.
`0008 First, the MIMO technology may be classified into
`a Spatial Multiplexing (SM) technique and a Spatial Diver
`sity (SD) technique according to the data transmission
`schemes. The SM technique is a technique for simulta
`neously transmitting different data by means of multiple
`antennas in a transmitter and a receiver, thereby transmitting
`data at a higher speed without increasing the bandwidth of
`the system. The SD technique is a technique for transmitting
`the identical data through multiple transmit (TX) antennas,
`thereby achieving the Transmit Diversity (TD).
`
`0009. The MIMO technology may also be classified into
`a closed-loop scheme, in which channel information is
`fedback from a receiver to a transmitter, and an open loop
`scheme, in which channel information is not fedback from
`a receiver to a transmitter.
`0010 Referring to the current standard documents
`802.16-REVd&D5, REVe/D5-2004 of the Institute of Elec
`trical and Electronics Engineers (IEEE) 802.16e standard,
`only a scheme for Supporting the MIMO technology using
`the open loop scheme has been proposed.
`SUMMARY OF THE INVENTION
`0011. Accordingly, the present invention has been made
`to solve at least the above-mentioned problems occurring in
`the prior art, and it is an object of the present invention to
`provide a method for Supporting various multiple antenna
`schemes based on MIMO technology in a BWA system
`using multiple antennas.
`0012. It is another object of the present invention to
`provide a method for Supporting various multiple antenna
`schemes by constructing an MAP message for classifying
`MIMO technology in a BWA system using multiple anten
`aS.
`0013. It is a further object of the present invention to
`provide a method for Supporting various multiple antenna
`schemes by constructing a downlink MAP message for
`efficiently providing multiple antenna technology, precoding
`or antenna grouping technology, antenna selection technol
`ogy, etc., which have feedback from a mobile station.
`0014. In order to accomplish the aforementioned objects,
`according to one aspect of the present, there is provided a
`method for supporting various Multiple Input Multiple Out
`put (MIMO) and precoding technologies in a Broadband
`Wireless Access (BWA) system employing an antenna tech
`nique of a MIMO scheme, the method including configuring
`a downlink MAP message that includes basic information
`fields for indicating the MIMO technology and information
`fields for indicating various precoding technologies; and
`applying the MIMO technology to a mobile station by
`means of the downlink MAP message.
`BRIEF DESCRIPTION OF THE DRAWINGS
`0015 The above and other objects, features and advan
`tages of the present invention will be more apparent from the
`following detailed description taken in conjunction with the
`accompanying drawings, in which:
`0016 FIG. 1 is a block diagram illustrating the construc
`tion of a transmitter, which includes a single encoder and a
`single modulator, capable of performing precoding by
`means of feedback information received from a mobile
`station in a BWA system according to an embodiment of the
`present invention;
`0017 FIG. 2 is a block diagram illustrating the construc
`tion of a transmitter, which includes a plurality of encoders
`and modulators, capable of performing preceding by means
`of feedback information received from a mobile station in a
`BWA system according to another embodiment of the
`present invention; and
`0018 FIG. 3 is a diagram illustrating available technol
`ogy according to the number of layers and streams according
`to an embodiment of the present invention.
`
`

`

`US 2006/0098568 A1
`
`May 11, 2006
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`Hereinafter, preferred embodiments according to
`0.019
`the present invention will be described with reference to the
`accompanying drawings. In the below description, many
`particular items, such as detailed elements, are shown, but
`these are provided for helping the general understanding of
`the present invention, and it is apparent to those skilled in the
`art that the particular items can be modified or varied within
`the scope of the present invention.
`0020. The present invention provides a method for using
`various Multiple Input Multiple Output (MIMO) schemes in
`a Broadband Wireless Access (BWA) communication sys
`tem using multiple antennas. Particularly, the present inven
`tion proposes a new downlink (DL)-MAP message in order
`to use a closed-loop MIMO scheme in a BWA communica
`tion system. The new DL-MAP message provides a method
`for selecting a transmission matrix corresponding to both the
`number of layers determined by the number of modulators
`and the number Mt of streams output from a Space Time
`Coding (STC) encoder. The STC encoder can be realized by
`a serial-to-parallel (S/P) converter. The transmission matrix
`has already been defined the IEEE 802.16 standard accord
`ing to a transmit diversity Scheme, a vertical encoding
`scheme and a horizontal encoding scheme.
`0021) When MIMO technology using the new DL-MAP
`message is applied to a BWA communication system, it is
`possible to make the closed-loop MIMO technology using
`the Channel Quality Information (CQI) fedback from a
`mobile station, i.e., a receiver, compatible with an exiting
`open loop MIMO technology having no feedback of the
`CQI. When the closed-loop MIMO technology is used, it is
`possible to perform a precoding.
`0022 FIG. 1 is a block diagram illustrating the construc
`tion of a transmitter, which includes a single encoder and a
`single modulator, capable of performing precoding by
`means of feedback information received from a mobile
`station in a BWA system according to an embodiment of the
`present invention.
`0023 Referring to FIG. 1, the transmitter includes an
`encoder 102 for performing coding for data 101 to be
`transmitted, a modulator 103 for mapping the coded data on
`a complex plane, an STC encoder 104 for applying basic
`MIMO technology to the modulated data, and a precoding
`block 105 for performing precoding for Mt number of
`streams received from the STC encoder 104. The precoding
`block 105 applies MIMO technology by using the CQI
`fedback from a mobile station. Further, the transmitter
`includes a Sub-carrier mapper 106 for mapping a symbol
`received from the precoding block 105, and an Inverse Fast
`Fourier Transform (IFFT) unit 107 for transforming the
`mapped symbol into an Orthogonal Frequency Division
`Multiple Access (OFDMA) symbol.
`0024. Because the transmitter includes one coder 102 and
`one modulator 103 as described above, the number of layers
`becomes one (L=1) and the STC encoder 104 outputs the Mt
`number of streams. Herein, MIMO technology for causing
`the Mt number of streams to acquire a diversity gain for
`common transmission signals corresponds to transmit diver
`sity technology. Further, MIMO technology for causing the
`Mt number of streams to acquire a gain for two or more
`
`separate transmission signals in view of a data rate will be
`referred to Vertical Encoding (VE) Spatial Multiplexing
`(SM) technology.
`0.025 The preceding block 105 receives the Mt number
`of streams and performs an MtxNt matrix operation. The Nt
`represents the number of transmit antennas.
`0026. The transmitter having the construction as
`described above receives channel feedback information and
`generates a matrix value of the precoding block 105, thereby
`operating by applying various MIMO algorithms such as
`feedback precoding (e.g., SVD precoding, beam forming
`preceding, etc), antenna grouping precoding, and antenna
`selection preceding.
`0027. The STC encoder 104 receives one input sequence
`so as to generate the Mt number of streams. When beam
`forming-precoding technology is applied, the STC encoder
`104 can output the Mt number of streams without perform
`ing STC encoding.
`0028 FIG. 2 is a block diagram illustrating the construc
`tion of a transmitter, which includes a plurality of encoders
`and modulators, capable of performing precoding by means
`of feedback information received from a mobile station in a
`BWA system according to another embodiment of the
`present invention.
`0029 Referring to FIG. 2, the transmitter includes a
`plurality of encoders 202a to 202n and modulators 203a to
`203n. Because the functions of the encoder and the modu
`lator have already been described with reference to FIG. 1,
`further detailed description will be omitted.
`0030 Herein, MIMO transmission technology applied to
`the transmitter having a plurality of layers will be referred to
`as a Horizontal Encoding (HE) spatial multiplexing tech
`nology.
`0.031) The STC encoder 204 receives L. number of input
`sequences so as to generate Mt number of streams. When
`beam forming-precoding technology is applied, the STC
`encoder 204 can output the Mt number of streams without
`performing STC encoding.
`0032 FIG. 3 is a diagram illustrating a scheme for
`applying a transmission matrix according to the number of
`layers and streams in a BWA communication system accord
`ing to an embodiment of the present invention.
`0033 Referring to FIG. 3, A, B and C represent trans
`mission matrices. Each of the STC encoders 104 and 204
`selects one transmission matrix according to the number of
`layers and streams in FIG. 3, thereby performing STC
`encoding. In the transmission matrix, a row index coincides
`with the number of antennas and a column index coincides
`with an OFDMA symbol time.
`0034) Equations 1 and 2 below represent sequential input
`symbol matrices of the STC encoders 104 and 204 of
`transmit diversity and spatial multiplexing when the Mt is 2.
`
`AM-2) =
`(Mt=2)
`
`S -S.
`S.
`
`(1)
`
`

`

`US 2006/0098568 A1
`
`May 11, 2006
`
`-continued
`
`TABLE 1-continued
`
`CM-2) =
`
`(2)
`
`0035 Equations 3 to 5 below represent sequential input
`symbol matrices of the STC encoders 104 and 204 of the
`transmit diversity, a hybrid of the transmit diversity and the
`spatial multiplexing, and the spatial multiplexing when the
`Mt is 3.
`
`S -s: 0
`
`0
`
`()
`()
`S.
`S.
`S. -S: Ss -S.
`BiM-3) = S, -ss S, -s;
`S. S.
`S. S;
`S
`CoM-3) = S2
`S3
`
`(3)
`
`(4)
`
`(5)
`
`0036) Equations 6 to 8 below represent sequential input
`symbol matrices of the STC encoders 104 and 204 of the
`transmit diversity, a hybrid of the transmit diversity and the
`spatial multiplexing, and spatial multiplexing when the Mt
`is 4.
`
`“M-4)
`
`S -S. ()
`S, S
`()
`o
`O s,
`()
`()
`S.
`
`()
`()
`is 4.
`S.
`
`S -S Ss -S.
`|S: Si
`S6 -'s
`M|S, -s; S, -s;
`S.
`S.
`Ss S,
`
`S.
`S2
`CM=4) = S.
`3
`S4
`
`(6)
`
`(7)
`
`(8)
`
`0037 Tables 1 to 3 below represent data formats of a
`MIMO-Compact DL-MAP message proposed as one
`example in order to efficiently provide all MIMO-based
`technologies in a BWA System according to an embodiment
`of the present invention.
`
`TABLE 1.
`
`Syntax
`MIMO Compact DL-MAP IE ( ) {
`Compact DL-MAP Type
`DL-MAP Sub-type
`
`Size
`(bits) Notes
`
`3
`5
`
`Type = 7
`MIMO = OxO1
`
`Syntax
`
`Length
`MIMO Type
`
`Num layer
`
`Mt
`
`Size
`(bits) Notes
`
`4 Length of the IE in Byte
`2 Type of MIMO Mode
`00 = Open-loop
`O1 = Antenna Grouping
`10 = antenna Selecting
`11 = Closed-loop
`Precoding
`2 Number of Multiple
`coding modulation layers
`00 = 1 layer
`01 = 2 layers
`10 = 3 layers
`11 = 4 layers
`2 Indicate number of STC
`output streams
`OO = 1 stream
`O1 = 2 streams
`10 = 3 streams
`11 = 4 streams
`
`0038 Table 2 below represents a message field subse
`quent to Table 1.
`
`TABLE 2
`
`Mode Change
`if (Mode Change = = 1){
`
`if (MIMO Type = = 00 or 11){
`if (MIMO Type = = 11){
`Precoding Index}
`
`Matrix Indicator
`if (MIMO Type = = 01){
`
`Antenna Grouping Index
`
`:
`
`If (MIMO Type = = 10){
`Antenna Selection Index
`
`If (H-ARQ Mode=CTC
`Incremental Redundancy) {
`
`elseif(H-ARQ Mode=Generic
`Chase)
`DIUC
`
`1 Indicates Change of MIMO
`mode O = No change
`from previous
`allocation
`1 = Change of MIMO mode
`
`6 Indicates the index of precoding
`Matrix Sec8.4.8.3.6
`2 Indicates open-loop matrix (Sec
`8.48.3)
`OO = Matrix
`A(Transmit Diversity)
`O1 = Matrix B
`(Hybrid scheme
`Allocation only for 3 and 4
`antennas)
`10 = Matrix C(Pure Spatial
`Multiplexing)
`11 = Reserved
`4 Indicates the index of antenna
`grouping Sec 8.4.8.3.4 and
`8.483.5
`
`4 Indicates the index of antenna
`selection Sec 8.4.8.3.4 and
`8.483.5
`
`This loop specifies the Nep for
`layers 2 and above
`when required
`for STC.
`The same Nsch
`and RCID applied
`for each layer
`4 H-ARQ Mode is specified in the
`H-ARQ Compact DL-MAP IE
`format for Switch H-ARQ Mode
`
`

`

`US 2006/0098568 A1
`
`May 11, 2006
`
`TABLE 2-continued
`
`if(CQICH indicator = = 1){
`
`Allocation Index
`
`:
`
`CQICH indicator comes
`from the precoding
`Compact DL-MAP IE
`6 Index to CQICH assigned to this
`layer, For the multi-layer MIMO
`transmission,
`the feedback type for
`this CQICH and that of the
`precoding Compact DL-MAP IE
`shall be 000.
`
`Table 3 below represents a message field subse
`0.039
`quent to Table 2.
`
`TABLE 3
`
`CQICH Num
`
`for (j=1:<CQICH NUM:j++){
`CQI Feedback type
`
`Period(p)
`
`for (i-0;izCQICH Num;i++){
`Allocation index
`
`2
`
`3
`
`2
`
`5
`
`Total number of CQICHs
`assigned to this SS is
`(CQICH Num + 1)
`00 = 1 CQICH
`O1 = 2 CQICH
`10 = 3 CQICH
`11 = 4 CQICH
`
`Type of contents on
`CQICH for this SS
`OOO = Fast D1,
`measurement
`Default Feedback
`001 = Precoding
`Weight Matrix
`information
`010 = Channel
`Matrix H
`011 = Adaptive
`Rate Control
`information
`OO = Antenna
`Selection Index
`O1-111 = Reserved
`Period of the
`additional (CQICH Num)
`CQI channels in frame
`index to uniquely
`identify the additional
`CQICH resources
`assigned to the SS
`
`padding
`
`variable The padding
`bits are used to
`ensure the IE size is integer
`number of bytes
`
`0040. In Table 1, the initial 8 bits of an MAP information
`element for providing MIMO-based control information
`represent a type of a MAP information element of 3 bits and
`a sub-type of 5 bits, and a length field of 4 bits represents
`length of the MIMO-based control information, which is
`located in the next field.
`0041. The construction of the control information will be
`described. The field MIMO type of 2 bits represents a
`MIMO mode. That is, when the field MIMO type has a
`value of 00, it indicates an open loop MIMO mode. When
`the field MIMO type' has a value of '01, it indicates an
`antenna grouping MIMO mode. When the field MIMO
`type has a value of 10, it indicates an antenna selection
`
`MIMO mode. When the field MIMO type has a value of
`11, it indicates a MIMO mode in which closed-loop
`precoding is performed.
`0042. The field Num-layer is a field for indicating the
`number of layers, which is the number of signal branches
`input to the STC encoder.
`0043. The field Mt is a field for indicating the number
`of streams output from the STC encoder. The transmitter
`determines the transmission matrices expressed by A, B and
`C in FIG. 3 by using the values of the field Num-layer and
`the field Mt. For example, when the field Num-layer has
`a value of 10 and the field Mt has a value of 10, the STC
`encoder performs STC encoding by using the horizontal
`encoding transmission matrix C.
`0044) The field Mode Change is a field for indicating if
`the MIMO mode has changed. For example, when the
`Mode Change has a value of 1, it means the use of a
`MIMO mode different from the previous MIMO mode.
`However, when the Mode Change has a value of 0, it
`means the current MIMO mode is identical to the previous
`MIMO mode. In this case, there is no changed information,
`it is not necessary to include the previous MIMO type
`information. Accordingly, it is possible to reduce the size of
`the Compact DL-MAP message.
`0045. When the field MIMO type' in Table 1 is desig
`nated to 00 or 11, it indicates a matrix index used in an
`open loop or a preceding matrix index used in a closed-loop.
`0046 Table 4 below or FIG. 3 represents combinations
`available according to the number L of layers and the
`number Mt of streams. Further, when the MIMO type has
`a value of 11, to which feedback precoding technology is
`designated, from among the closed-loop MIMO types, it
`indicates a corresponding feedback precoding matrix
`through an index of 6 bits for feedback precoding while the
`STC encoder is used. Herein, the feedback preceding matrix
`may have a size of Mt (the number of streams)xNt (the
`number of transmit antennas) and 64 different matrices at
`maximum, and the feedback precoding matrix may have a
`value depending on a generation algorithm, the number of
`layers, the number of streams, and the number of transmit
`antennas.
`
`Matrix Indicator
`
`This field indicates
`MIMO matrix for the
`burst.
`
`TABLE 4
`if (Num layer = 1){
`if (Mt = 1){
`SISO or AAS mode :
`elseif (Mt = 2){
`00 = A(TD):01 = C(VE):10 11 = Reserved
`elseif (Mt = 3){
`OO = A(TD):01 = B(VE):10 = C(VE) 11 =
`Reserved
`elseif (Mt = 4){
`OO = A(TD):01 = B(VE):10 = C(VE) 11 =
`Reserved
`else if (Num layer = 2){
`if (Mt = 2){
`00 = C(HE):01 11 = Reserved
`elseif (Mt = 3){
`00 = B(HE):01 11 = Reserved
`elseif (Mt = 4){
`00 = B(HE):01 11 = Reserved
`
`

`

`US 2006/0098568 A1
`
`May 11, 2006
`
`TABLE 4-continued
`elseif (Num layer = 3){
`if (Mt = 3){
`00 = C(HE):01 11 = Reserved
`elseif (Num layer = 4){
`if (Mt = 4){
`00 = C(HE):01 11 = Reserved
`
`0047. When the MIMO type in Table 1 has a value of
`01 and antenna grouping technology is designated, it may
`indicate an antenna precoding matrix through an antenna
`grouping index of 4 bits in Table 2.
`0.048 Table 5 below represents matrix combinations that
`may be indicated by the antenna grouping index of 4 bits in
`Table 2. Herein, the MIMO technologies in FIG.3 to be first
`applied are determined by the number of layers and the
`number Mt of streams in Table 1, and the MIMO technology
`to be finally applied is determined by the field antenna
`grouping index of 4 bits as expressed by Table 5 below.
`0049. As described above, STC encoding technology to
`be applied of the STC encoders 104 and 204 can be
`determined by the single field antenna grouping index of 4
`bits, and matrix values of the precoding blocks 105 and 205
`can be similarly understood. Accordingly, it is possible to
`efficiently reduce overhead of the control information mes
`Sage.
`
`TABLE 5
`
`Antenna Grouping Index
`This field indicates antenna Grouping Index for the current burst.
`if (Num layer = 1){
`if (Mt = 3){
`0000 = A1:0001 = A2: 0010 = A3;
`O011 = B1 (VE): 0100 = B2(VE); 01.01 = B3(VE):
`0110–1111 = Reserved
`elseif (Mt = 4){
`0000 = A1:0001 = A2: 0010 = A3;
`O011 = B1 (VE): 0100 = B2(VE); 01.01 = B3(VE): 0110 = B4(VE):
`O111 = B5 (VE); 1000 = B6(VE):
`1001–1111 = Reserved
`elseif (Num layer = 2){
`if (Mt = 3){
`0000 = B1 (HE); 0001 = B2(HE); 0010 = B3 (HE):
`O011–1111 = Reserved
`elseif (Mt = 4){
`0000 = B1 (HE); 0001 = B2(HE); 0010 = B3 (HE); 0011 = B4(HE):
`01.00 = B5 (HE): 0101 = B6(HE):
`0110–1111 = Reserved
`
`0050. When the MIMO type in Table 1 has a value of
`10 and antenna selection technology is designated, it may
`indicate a precoding matrix through the field antenna selec
`tion index of 4 bits in Table 2. This indicates an antenna
`selected by performing an operation identical to that for the
`antenna grouping index.
`0051) The field including the N or the Downlink Inter
`val Usage Code (DIUC) in table 2 indicates coding rates and
`modulation schemes for sets of encoders and modulators,
`which correspond to the number of layers, through a value
`of 4 bits. That is, when a plurality of layers exists, the field
`
`indicates a coding rate and a modulation scheme by a N.
`scheme in a Hybrid Automatic Request (H-ARQ) supple
`mentary information retransmission (that is, Incremental
`Redundancy) mode. Further, when at least one layer
`includes an error in a mobile station, a non acknowledge
`ment (NACK) is generated and combination data for coding
`gain increases for data of all layers are retransmitted. Fur
`ther, when the Channel Quality Information Channel
`(CQICH) is assigned, the last field indicates CQICH channel
`allocation information in order to load single CQI feedback
`information on each layer. Because each layer uses different
`encoding and modulation schemes as described above, each
`layer requires CQI feedback information.
`0.052 Table 3 illustrates the fields that a mobile station
`must refer to in order to feedback the CQI in a structure
`having multiple antennas or multiple layers. The field
`CQICH-NUM representing the number of feedback chan
`nels denotes the number of feedback channels to be simul
`taneously transmitted by the mobile station. The field CQI
`Feedback type', which indicates the type of feedback infor
`mation to be transmitted from each feedback channel,
`enables the mobile station to transmit different feedback
`information according to each allocated feedback channel.
`This enables the mobile station to transmit various feedback
`information required by a base station, thereby leading to
`more efficient operation of the MIMO technology.
`0053 As described above, the transmitter, i.e., the base
`station, determines at least one matrix from among a plu
`rality of transmission matrices by considering information
`fedback from the receiver, i.e., the mobile station, thereby
`performing STC encoding or precoding by means of the
`determined matrix and transmitting information for the
`determined matrix to the mobile station through a MIMO
`Compact DL-MAP message newly proposed by the present
`invention. Herein, the mobile station can understand the
`information for the matrix with reference to information for
`the layer values and the Mt values transmitted from the base
`station. Accordingly, the mobile station can perform decod
`ing by using the transmission matrix corresponding to the
`information for the layer values and the Mt values while
`having already recognized the information as described in
`FG, 3.
`0054 According to the present invention as described
`above, it is possible to efficiently notify a mobile station of
`various basic technologies for a MIMO and various MIMO
`precoding technologies using only a small quantity of data
`through downlink MAP message in a BWA system, thereby
`improving performance of the BWA System and increasing
`its cell capacity.
`0055 While the present invention has been shown and
`described with reference to certain preferred embodiments
`thereof, it will be understood by those skilled in the art that
`various changes in form and details may be made therein
`without departing from the spirit and scope of the present
`invention as defined by the appended claims.
`
`What is claimed is:
`1. A method for supporting various Multiple Input Mul
`tiple Output (MIMO) and precoding technologies in a
`Broadband Wireless Access (BWA) system employing an
`antenna technique of a MIMO scheme, the method com
`prising the steps of
`
`

`

`US 2006/0098568 A1
`
`May 11, 2006
`
`configuring a downlink MAP message including infor
`mation fields for indicating the MIMO technology and
`information fields for indicating various precoding
`technologies; and
`applying the MIMO technology to a mobile station by
`means of the downlink MAP message.
`2. The method as claimed in claim 1, wherein the down
`link MAP message includes a field representing coding and
`modulation information according to layers and a field list
`information for Channel Quality Information (CQI) alloca
`tion.
`3. The method as claimed in claim 2, wherein the down
`link MAP message includes a field representing a number of
`streams output from a Space Time Coding (STC) encoder,
`and indicates applicable MIMO technology in the field
`representing the coding and modulation information.
`4. The method as claimed in claim 3, wherein the down
`link MAP message includes a field for indicating if a
`Supportable mode has changed, and indicates a type of the
`STC encoder through a number of layers included in the
`field representing the coding and modulation information,
`the number of streams, and a value of the basic information
`field.
`5. The method as claimed in claim 1, wherein the step of
`applying the MIMO technology comprises the sub-steps of:
`determining MIMO technology to be applied based on a
`number of layers and a number of streams designated
`in the downlink MAP message, when the information
`field for indicating various precoding technologies,
`which is included in the downlink MAP message, is
`designated as antenna grouping precoding technology:
`determining MIMO technology to be applied by an
`antenna grouping index field designated in the down
`link MAP message; and
`applying the determined MIMO technology.
`6. A method for Supporting multiple antennas by a base
`station in a Broadband Wireless Access (BWA) communi
`cation system using a Multiple Input Multiple Output
`(MIMO) scheme, the method comprising the steps of:
`receiving Channel Quality Information (CQI) from a
`mobile station;
`determining the MIMO scheme according to the CQI;
`encoding data according to the determined MIMO
`Scheme; and
`configuring a downlink MAP message including the
`encoded data and information used for the encoding,
`and transmitting the downlink MAP message.
`7. The method as claimed in claim 6, wherein the MIMO
`scheme determines a transmission matrix according to a
`
`number of layers corresponding to a number of modulators
`and a number of modulation streams output from an encoder
`in a transmitter of the base station.
`8. The method as claimed in claim 6, wherein the encod
`ing includes one of a transmit diversity scheme, a vertical
`encoding scheme and a horizontal encoding scheme.
`9. The method as claimed in claim 6, wherein the infor
`mation used for the encoding includes information defining
`a number of layers corresponding to a number of modulators
`and a number of modulation streams output from an encoder
`in a transmitter of the base station, and transmits to the
`mobile station a downlink MAP message for indicating a
`transmission matrix determined by the number of layers and
`modulation streams.
`10. The method as claimed in claim 6, wherein the
`information used for the encoding includes information
`defining a number of layers corresponding to a number of
`modulators and a number of modulation streams output from
`an encoder in a transmitter of the base station, and transmits
`to the mobile station a downlink MAP message for indicat
`ing antenna grouping/selection index information deter
`mined by the number of layers and modulation streams.
`11. An apparatus of a base station for application of a
`Multiple Input Multiple Output (MIMO) scheme in a Broad
`band Wireless Access (BWA) communication system using
`the MIMO scheme, the apparatus comprising:
`a first encoder for encoding data;
`a modulator for mapping on a complex plane the encoded
`data output from the first encoder;
`a second encoder for applying the MIMO scheme to the
`modulated data; and
`a precoding block for receiving a modulation stream from
`the second encoder and performing precoding for the
`received modulation stream.
`12. The apparatus as claimed in claim 11, wherein the
`second encoder includes a Space Time Coding (STC)
`encoder for performing space time coding.
`13. The apparatus as claimed in claim 11, wherein the
`precoding block operates when receiving Channel Quality
`Information (CQI) fedback from a mobile station.
`14. The apparatus as claimed in claim 11, wherein the
`MIMO scheme determines a transmission matrix according
`to a number of layers corresponding to a number of modu
`lators and a number of modulation streams output from the
`second encoder in a transmitter of the base station.
`15. The apparatus as claimed in claim 11, wherein the
`second encoder uses one of a transmit diversity Scheme, a
`vertical encoding scheme and a horizontal encoding scheme.
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