WIRELESS COMMUNICATION DEVICE AND WIRELESS COMMUNICATION METHOD

DESCRIPTION
Title of the Invention: WIRELESS COMMUNICATION DEVICE AND WIRELESS COMMUNICATION METHOD
Technical Field [0001] The present invention relates to a wireless communication device and a wireless communication method using a multiuser MIMO technology.
Background Art [0002] In recent years  demands for larger capacity and higher speed of a wireless communication have been growing  and methods for improving an effective availability of finite frequency resources have been actively researched. As one of those methods  attention has been attracted to a technique using a space domain. [0003] In a MIMO (multiple input multiple output) technology  a plurality of antenna elements are equipped in each of a transmitter and a receiver  and spatial multiplexing transmission is realized under a propagation environment that is low in correlativity ofreception signals among antennas (refer to Non""patent Literature 1). In this case  the transmitter transmits different data series from a plurality of attached antennas by using a physical channel having the same time  the same frequency  and the same code for each antenna element. -The receiver separates and receives the reception signals from a plurality of attached antennas on the basis of the different data series. In this way  a plurality of spatial multiplexing channels is used so that high speed can be achieved without using multilevel modulation. When the transmitter and the receiver are equipped witll the same number of antennas under the environments where a large number of scatters exist between the transmitter and the receiver in a sufficient SIN (signal to noise ratio) condition  a communication capacity can be enlarged in proportion to the number of antennas. [0004] Also  as another MIMO technology  a multiuser MIMO technology (multiuser MIMO  or MU""MIMO) has been known. The MU""MIMO technology has been already discussed in a next""generation wireless communication system standard. For example  in a draft of 30PP LTE
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standard or IEEE 802  16m standard (hereinafter referred to as "16m")  the standardization of a transmission system using the multiuser MIMO has been included (refer to Non-patent Literature 2 and Non-patent Literature 3)  Hereinafter  as one example  a description will be given of an outline of the multiuser MIMO system in a downlink in the 16m  [0005] FIG  21 illustrates a frame format in a downlink.
In the figure  SFn (n = an integer of 0 to 7) denotes a subframe  In transmitting individual data of a terminal (or user) using an individual data area (blocks indicated by DL in the figure) in the downlink  a base station device allows control information such as terminal allocation information to be included in a signal to be transmitted from the base station device to a terminal device existing within a communication area  In the 16m  the base station device allows the control information to be included in areas allocated as A-MAP in FIG  21. [0006] FIG  22 illustrates an example of main parameters included in the control information (individual control information) for a specific terminal device MS#n  Resource allocation information RA#n that is one of the parameters illustrated in FIG  22 includes information related to a position  an allocation size  and distributed/continuous mapping of a transmission area of individualdata of the terminal (or user) in the individual data area DL to be transmitted by using an OFDM symbol subsequent to A-MAP. [0007] In MIMO mode information MEF illustrated in FIG  22  transmission information of a spatial multiplexing mode or a temporal-spatial diversity transmission mode is transmitted  When the MIMO mode information MEF indicates the MU-MIMO mode  the MIMO mode information MEF further includes pilot sequence information PSI#n and the number of spatial streams Mt in the MU-MIMO as a whole  The MCS information notifies the terminal device MS#n of modulation multi-level value of the spatial stream and code rate information  [0008] The MCRC#n that is terminal destination information illustrated in FIG  22 is CRC information masked with terminal identification information CID (connection ID) allocated to the terminal MS#n by the base station device at the time of establishing a connection  With this information  the terminal device detects individual control information addressed to the own station together with error detection  [0009] A description will be given of the operation of a conventional base
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station device 80 that performs the above-mentioned MU-MIMO transmission with reference to FIG. 23. FIG. 23 is a block diagram illustrating a configuration of the conventional base station device 80 and a conventional terminal device 90 (terminal device MS#n; n is a natural number). The base station device 80 illustrated in FIG. 23 notifies the individual terminal of the MU-MIMO allocation information through a downlink individual control channel allocated as an A-MAP  prior to the MU-MIMO transmission. As illustrated in FIG. 22  the MU-MIMO allocation information includes  as parameters necessary for a receiving process at the terminal device MS#n side  the number of spatial streams (Mt)  the code rate and modulation information MCS#n of the error correcting code performed on a spatial stream addressed to MS#n  pilot information (PSI#n) addressed to the MS#n  and resource allocation information RA#n addressed to the MS#n. In this case  n=l  ... Mt. Also  it is assumed that one spatial stream is allocated to the terminal device MS#n. [0010] A control information and data generator 84#n includes an individual pilot generator 85  a modulated data generator 86  a precoding weight multiplier 87  and an individual control information generator 88  and generates individual control information and data for the terminal device MS#n. [oon] The individual control information generator 88 generates an individual control signal including the above-mentioned MU-MIMO allocation information. The modulated data generator 86 generates a modulated data signal #n addressed to the terminal device MS#n that performs the spatial multiplexing transmission on the basis of the code rate and modulation information MCS#n. The individual pilot generator 85 generates a pilot signal #n used for channel estimation on the basis of pilot information (PSI#n) addressed to the MS#n. The precoding weight multiplier multiplies the modulated data signal #n by the pilot signal #n with the use of a common precoding weight #n to generate spatial streams. The spatial multiplexing streams are generated by the number of spatial multiplexing streams (Mt) by the control information and cjata generator 84#n1  ... #Mt.
[0012] An OFDM symbol configuration section 81 allocates an individual control signal to an A-MAP control information area on an OFDM symbol. Further  the spatial streams that are individual data addressed to Mt
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terminal devices are mapped to a source based on the resource allocation information RA#n by spatial mUltiplexing. IFFTs sections 82 performs OFDMA modulation on an output of the OFDM symbol configuration section  and add a cyclic prefiex (or guard interval) thereto. After frequency conversion  the outputs are transmitted from respective antennas 83. [0013] In this case  because in a precoded MIMO propagation channel the channel estimation can be performed with the use of the pilot signal precoded by the same precoding weight as that of the data signal  the MIMO mode information requires no precoding information. [0014] Also  the MIMO propagation channel in the terminal device MS#n can be estimated with the use ofsignals orthogonal to each other between the spatial multiplexing streams using frequency division as the respective pilot signals. [0015] On the other hand  the terminal device MS#n performs the following terminal receiving process. First  the terminal device MS#n detects the MU-MIMO allocation information addressed to the own terminal device from a downlink individual control signal received by a downlink control information detector 92 through antennas 91. Then  the terminal device MS#n extracts data in an area where the resource is allocated to the MU-MIMO transmission from data in which OFDMA demodulation not shown has been performed. [0016] Then  an MIMO separator 93 performs the channel estimation of the MIMO propagation channel with the use of the pilot signal precoded by the number of spatial multiplexing streams (Mt). Further  the MIMO separator 93 generates a reception weight based on MMSE criteria on the basis of the result of the channel estimation of the MIMO propagation channel and pilot information (PSI) addressed to the own terminal device  and separates a stream addressed to the own terminal device from the data in the resource allocated area which has been spatially multiplexed. Then  after separation of the stream addressed to the own terminal device  the terminal device MS#n demodulates and decodes the stream with the use of the MCS information by a demodulator/decoder 94.
[0017] In this case  the resource allocation information RA#n addressed to the MS#n which is a parameter required for the receiving process at the terminal device MS#n side includes distributed/continuous mapping information  position (start  end) information  and allocation size
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information.
[0018] In the 16m  the resources are placed on the basis of a physical
resource unit (PRU) including a given OFDM symbol and sub carrier. A
given number of pilot signals are arranged within the PRD.
[0019] FIG. 24 illustrates an example of a physical resource unit (PRU)
configuration at the time of transmitting two streams. The PRU illustrated
in FIG. 24 includes 6 OFDM symbols and 18 subcarriers. The PRU includes
12 pilot symbols (blocks indicated by 1 or 2 in the figure) and 96 data
symbols.
[0020] Also  there are two kinds of resource allocation methods which are a
continuous mapping (Continuous Resource Unit (CRU) or localized Resource
Unit)  and a distributed mapping (Distributed Resource Unit (DRU». The
continuous mapping continuously allocates a resource to the terminal device
with the subcarriers whose reception quality is relatively high  on the basis
of a reception quality status from the terminal device. This is a resource
allocation method particularly suitable for a case in which a travel speed of
the terminal is low  and a temporal change inthe reception quality is gentle . .On the other hand  the distributed mapping allocates the resources
distributed on the subcarriers to the terminal to easily obtain a frequency
diversity effect. This is a resource allocation method particularly suitable
for a case in which the travel speed of the terminal is high  and the temporal
change in the reception quality is severe.
[0021]
Subsequently  a description will be given of the continuous mapping
that is the resource allocation method with reference to FIG. 25.
The individual data of the user (individual data or user individual
data) which is transmitted to the terminal device  individually  is allocated to
the physical resource unit PRU with a logical resource unit (LRU) as a unit.
In this example  the LRU includes data as much as the number of data
symbols except for the pilot symbols included in the PRU  and is allocated to
a data symbol placed portion in the physical resource PRU in a given order.
Also  the LRU is allocated to the continuous subcarriers with one PRU as a
unit (hereinafter called "miniband unit") or n plural PRUs as an assembled
unit (hereinafter called "subband unit"). FIG. 25 illustrates an example of
the resource continuous mapping using the subband of n=4. As illustrated
in FIG. 25  in the individual data of the user  LRU#l to LRU #4 are allocated
to PRU#l to PRU#4  respectively. [0022] Subsequently  a description will be given of the distributed mapping that is the resource allocation method with reference to FIG. 26.
The individual data of the user which is transmitted to the terminal device  individually  is allocated to the physical resource unit PRU with the logical resource unit LRU as a unit. In this example  the LRU includes data as much as the number of data symbols except for the pilot symbols included in the PRU A sub carrier interleaver (or tone permutation) distributes a plurality of LRU data into a plurality of PRU in conformity to a given rule. [0023] As illustrated in FIG. 26  when a transmission diversity manner sllch as an SFBC (space-frequency block coding) is applied in the subcarrier leaver. in order to ensure continuity between two subcarriers  the distributed mapping is performed with the two subcarriers as one unit (two-subcarrier based interleaver or two-tone based permutation).
The SFBC is disclosed in Non-patent Literature 6. [0024] Also  when the maximum likelihood estimation (MLD) reception that obtains a high reception quality at the time of receiving the MU -MIMO is applicable in the terminal device  "modulation information on the spatial streams addressed to another user" which are spatially multiplexed at the same time is further included in the individual control inform:J.tion. [0025] FIG. 27 illustrates an example of bit allocation (per one user) of the modulation information on another user as disclosed in Non-patent literature 5. Referring to FIG. 27  another user is informed of any modulation format of QPSK  16QAM  and 64QAM (constellation information at the time of modulation) by use of 2 bits.
Citation List
Non-patent Literatures
[0026] Non-patent Literature 1: G. J. Foschini  "Layered space-time
architecture for wireless communication in a fading environment when using
multi-element antennas"  BellLabs Tech. J. Autumn of 1996  pp. 41-59
Non-patent Literature 2: 3GPP TS36.211 VS.3.0 (200S-05)
Non-patent Literature 3: IEEE S02.1Bm-09/0010r2  "Air Interface for
Fixed and Mobile Broadband Wireless Access Systems: Advanced Air
Interface (working document)"
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Non"patent Literature 4: Collection of Standard Technology of Japanese Patent Office (MIMO Related Art) https:Ilwww.jpo.go.jp/shiryou/s_sonota/hyoujun_gijutsu/mimo/mokuji.htm
Non"patent Literature 5: IEEE C802  16m"09/1017  "Text proposal on DL MAP"  Amir Khojastepour  Narayan Prasad  Sampath Rangarajan  Nader Zein  Tetsu Ikeda  Andreas Maeder (2009-04"27)
Non"patent Literature 6: King F  Lee and Douglas B  Williams  "Space"Frequency Transmitter Diversity Technique for OFDM Systems"  IEEE GLOBECOM2000  Vol. 3 2000  pp  1473"1477
Summary of the Invention Technical Problem [0027] In the above-mentioned MU"MIMO transmission  a plurality of terminals (users) share the same physical resources by spatial multiplexing  In this case  there is a method in which the users having common allocation size notified as the resource allocation information RA included in the individual control information are allocated as the MU"MIMO users  The method will be described with reference to FIG  28  FIG  28 is a diagram illustrating an example of the allocation of the MU"MIMO user  The axis of ordinate in FIG  28 expresses an index of the spatial stream  and the axis of abscissa in FIG  28 expresses an index of the resource  In this example  the MU"MIMO area represented in the axis of abscissa in FIG  28 represents the resource allocation area to which the resource that performs the spatial multiplexing transmission is allocated  [0028] In FIG  28  the users having common allocation resource size are MU"MIMO"allocated to each of two users (User#l  User#2) by the use of one spatial stream (the number of spatial multiplexing is 2)  The MU-MIMO user allocation method illustrated in FIG  28 has such an advantage that the transmission can be performed with the use of the minimum resource without wasting the spatial resource for the same physical resource and for satisfying a given reception quality  [0029] However  in the MU"MIMO user allocation method illustrated in FIG  28  there isa need to perform the MU"MIMO transmission by combining the users having common allocation source size together  and a load of a scheduler that performs the user allocation in performing the MU"MIMO is increased  Also  when the number of combinations of the users having
; -""
common allocation resource size is small  the MU-MIMO transmission mode cannot be used  leading to a loss of chances for performing the MU-MIMO transmission. As a result  in the MU-MIMO user allocation method illustrated in FIG. 28  the spatial multiplexing transmission cannot be flexibly used  and the frequency use efficiency is degraded. [0030] On the other hand  there is a method in which the users having different allocation resource sizes notified as the resource allocation information RA included in the individual control information are allocated as the MU-MIMO users. FIG. 29 is a diagram illustrating another example of the allocation of the MU-MIMO user. The axis of ordinate in FIG. 29 expresses an index of the spatial stream  and the axis of abscissa in FIG. 29 expresses an index of the resource. In this example  the MU-MIMO area represented in the axis of abscissa in FIG. 29 represents the resource allocation area of the user to which the maximum resource size is allocated among a plurality of users who perform the spatial multiplexing transmission at the same time  in performing the MU-MIMO transmission. [0031] In FIG. 29  the users having different allocation resource sizes are MU-MIMO-allocated to each of two users (User#l  User#2) by the use of one spatial stream (the number of spatial multiplexing is 2). As illustrated in FIG. 29  a portion (shaded portion in the figure) that does not satisfy the MU-MIMO area that performs the MU-MIMO transmits additional data to the User#2 that is a user having small allocation resource size as the user data of the User#2  to thereby effectively use the spatial resource. In this example  the additional data added as the user data of the User#2 excessively adds a parity bit obtained in conducing error correction coding  and transmits the parity bit (parity bit addition transmission). Alternatively  the addition data added as the user data of the User#2 repetitively transmits the bit series of a specific portion (repetition bit transmission). [0032] In the MU-MIMO user allocation method illustrated in FIG. 29  even in the combination of the users having different allocation resource sizes  because the MU-MIMO transmission mode can be used  a load of the scheduler that performs the user allocation in performing the MU-MIMO is reduced. Also  the chances for performing the MU-MIMO transmission are increased. For that reason  in the MU-MIMO user allocation method illustrated in FIG. 29  because the spatial multiplexing transmission can be
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flexibly used  even if the number of combinations of the users having common allocation resource size is small  the frequency use efficiency can be improved. Also  because of the transmission of the additional data  the user having small allocation resource size obtains the effect of improving the reception quality. In FIG. 29  the reception quality of the user User#2 allocated to the spatial stream #2 is improved. [0033) However  in the MU-MIMO user allocation method illustrated in FIG. 29  when the resource size of the user having small allocation resource size is sufficiently small with respect to the MU-MIMO area  the data reception quality of the user becomes an excessive quality. On the other hand  the reception quality of the spatial stream of the users large in the allocation resource size is not changed  resulting in such a problem that the reception quality among the spatial streams is biased.
[0034) An object of the present invention is to provide a wireless communication device and a wireless communication method  which can
suppress a bias of the reception quality among the spatial streams to the plurality of terminal device.
Solution to Problems [0035] A wireless communication device according to an aspect of the invention is a wireless communication device for performing a spatial multiplexing transmission with respect to a plurality of terminal devices  the wireless communication device including: an additional data area setting section that is configured to allocate  as an additional data area  a part of a resource allocation area to which no data addressed to each terminal device of the plurality of terminal devices is allocated among resource allocation areas for the spatial multiplexing transmission which are allocated to each terminal device of the plurality of terminal devices; an additional data generator that is configured to generate additional data corresponding to the additional data area allocated by the additional data area setting section; and a transmitter that is configured to transmit the data which is addressed to each terminal device of the plurality of terminal devices and the additional data. [0036] A wireless communication device according to an aspect of the invention is also a wireless communication device for performing a spatial multiplexing transmission with respect to a plurality of terminal devices  the
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wireless communication device including: a null data area setting section that is configured to allocate  as a null data area  a part of a resource allocation area to which no data addressed to each terminal device of the plurality of terminal devices is allocated among resource allocation areas for the spatial multiplexing transmission which are allocated to each terminal device of the plurality of terminal devices; a null data area signal generator that is configured to generate a null data signal to be transmitted to each terminal device of the plurality of terminal devices in the null data area; and a transmitter that is configured to transmit the data which is addressed to the plurality of terminal devices and the null data signal. [0087] A wireless communication method according to an aspect of the invention is a wireless communication method for performing a spatial multiplexing transmission with respect to a plurality of terminal devices  the wireless communication method including: an additional data area setting step of allocating  as an additional data area  a part of a resource allocation area to which no data addressed to each terminal device of the plurality of terminal devices is allocated among resource allocation areas for the spatial mUltiplexing transmission which are allocated to each terminal device of the plurality of terminal devices; an additional data generating step of generating additional data corresponding to the additional data area allocated by the additional data area setting section; and a transmitting step of transmitting the data which is addressed to each terminal device of the plurality of terminal devices and the additional data. [0088] A wireless communication method according to an aspect of the invention is also a wireless communication method for performing a spatial multiplexing transmission with respect to a plurality of terminal devices  the wireless communication method including: a null data area setting step of allocating  as a null data area  a part of a resource allocation area to which no data addressed to each terminal device of the plurality of terminal devices is allocated among resource allocation areas for the spatial multiplexing transmission which are allocated to each terminal device of the plurality of terminal devices; a null data area signal generating step of generating a null data signal to be transmitted to each terminal device of the plurality of terminal devices in the null data area; and a transmitting step of transmitting the data which is addressed to the plurality of terminal devices and the null data signal.
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Advantageous Effects of the Invention [0039] According to the wireless communication device and the wireless communication method of the present invention  the bias of the reception quality among the spatial streams to the plurality of terminal device can be suppressed in the multiuser MIMO transmission 
Brief Description of the Drawings [0040] FIG  1 is a diagram illustrating a configuration of a base station device 100 according to a first embodiment 
FIG  2 is a diagram illustrating a resource allocation status in performing MU•MIMO transmission  FIG  3 is a diagram illustrating a channel estimation range using a subband unit. In FIG  4  (a) and (b) are diagrams illustrating examples of mapping of a pilot sequence and mapping of a data series in two streams  respectively.
FIG  5 is a diagram illustrating an example of mapping to a PRU 
FIG  6 is a block diagram illustrating a configuration of a terminal device 200 according to the first embodiment 
FIG  7 is a diagram illustrating a processing procedure between a base station device 100 and the terminal device 200 according to the first embodiment 
FIG  8 is a block diagram illustrating a configuration of a base station device 100A. FIG  9 is a schematic diagram illustrating a transmission power control example (1) of a spatial stream power controller 143  FIG  10 is a schematic diagram illustrating a transmission power control example (2) of the spatial stream power controller 143  FIG  11 is a diagram schematically illustrating a resource allocation status in a two""userMU""MIMO mode according to the first embodiment. FIG  12 is a block diagram illustrating a configuration of a base station device 300 according to a second embodiment  FIG  13 is a diagram schematically illustrating a resource allocation status in the two""user MU•MIMO mode according to the second embodiment  FIG  14 is a block diagram illustrating a configuration of a base station device 500 according to a third embodiment 
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FIG. 15 is a diagram schematically illustrating a resource allocation status including a repetitive symbol data area in the two""user MU""MIMO mode according to the third embodiment.
FIG. 16 is a block diagram illustrating a configuration of a terminal device 600 according to the third embodiment. FIG. 17 is a block diagram illustrating a configuration of an MIMO receiving processor 609. FIG. 18 is a block diagram illustrating a configuration of an MIMO receiving processor 609A. FIG. 19 is a block diagram illustrating a configuration of an MIMO receiving processor 609B of a terminal device 600B. FIG. 20 is a schematic diagram in a case of setting a repetitive symbol period with liN of an LRU as a unit in the two""user MU•MIN mode. FIG. 21 is a diagram illustrating a frame format in a downlink discussed in an IEEE 802.16m standard draft. FIG. 22 is a diagram illustrating an example ofMU""MIMO allocation information for an n•th terminal device MS#n. FIG. 23 is a block diagram illustrating configurations of a conventional base station device 80 and a conventional terminal device 90. FIG. 24 is a diagram illustrating an example of a PRU configuration in a two""stream transmission mode. FIG. 25 is a diagram illustrating a continuous mapping according to one resource allocation method. FIG. 26 is a diagram illustrating a distributed mapping according to another resource allocation method. FIG. 27 is a diagram illustrating an example of bit mapping of modulation information on another user. FIG. 28 is a diagram illustrating one example of allocation of an MU•MIMO user. FIG. 29 is a diagram illustrating another example of allocation of the MU•MIMO user.
Modes for Carrying out the Invention
[0041] Hereinafter  embodiments of the present invention will be described
with reference to the drawings.
[0042] (First Embodiment)
A first embodiment will be described with reference to FIGS. 1 to 11. FIG. 1 is a diagram illustrating a configuration of a base station device 100 according to the first embodiment. FIG. 1 illustrates the configuration of a case in which the base station device 100 performs multiuser MIMO transmission with respect to a terminal device MS#l to a terminal device MS#S  which are S number of terminal devices 200  as an example. [0042] The base station device 100 illustrated in FIG. 1 includes a plurality of antennas 101 configuring a base station antenna  a receiver 103  a feedback information extractor 105  a terminal device allocator 107  a resource allocation information extractor 109  an additional data area setting section 111  a null data area setting section 113  a pilot sequence allocator 115  an individual control signal and individual data signal generator 120  an OFDMA frame-forming section 151  a plurality of IFFT sections 153  and a plurality of transmitters 155. A configuration of the individual control signal and individual data signal generator 120 will be described later. [0044] The base station antenna includes the plurality of antennas 101 that receive and transmit a high-frequency signal. [0045] The receiver 103 demodulates and decodes a reception signal from the base station antenna. [0046] The feedback information extractor 105 extracts feedback information transmitted by the terminal device MS#n  from data decoded by the receiver 103. In this example  the feedback information from the terminal device MS#n includes reception quality information and desired precoding weight information. In this example  n is a value of 1 to S. [0047] The terminal device allocator 107 determines the combination of the terminal devices that perform the multiuser MIMO transmission  tbe resource allocation of a frequency or a time to the terminal devices used for the multiuser MIMO transmission  and a transmission format to each terminal device (modulation multi-level value  the code rate of the error correcting code  or the precoding weight) on the basis of the feedback information extracted by the feedback information extractor 105 so as to satisfy a required quality. [0048] [Resource Allocation in MU-MIMO Transmission]
Hereinafter  a description will be given in detail of the resource allocation in the MU-MIMO transmission  which is one feature of the present
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invention  The terminal device allocator 107 determines the resource allocation information RA#l to #S with respect to the plurality of terminal devices MS#l to #S that perform the MU-MIMO transmission  respectively. In this example  the resource allocation information RA#l to #S includes the following three pieces of information  The terminal device allocator 107 determines those pieces of information  [0049] As one piece of information of the resource allocation information RA#l to #S  the terminal device allocator 107 determines the resource allocation size when using the MCS necessary to satisfy the required quality  as a size RA_SIZE#l to #S which is an integral multiple of a basic unit with an LRU as the basic unit  .on the basis of the amount of data to be transmitted to the respective terminal devices MS#l to #S  and the reception quality status fed back from the terminal device MS#n  [0050] As one piece of information of the resource allocation information RA#l to #S  the terminal device allocator 107 determines start positions (RA_START#l to #S) of the resource allocation with the use of an index of the LRD. [0051] As one piece of information of the resource allocation information RA#l to #S  the terminal device allocator 107 determines whether a distributed mapping (DRU) or a continuous mapping (CRU)  which is a allocation method (RA_PLACEMENT)  is used  The allocation method is common to all of the terminal device MS#l to #S that perform the multiuser MIMO transmission  [0052] Hereinafter  in this embodiment  a description will be given of a case in which the terminal device allocator 107 determines that only the continuous mapping (CRU) is used as the allocation method (RA_placement)  [0053] The resource allocation information extractor 109 extracts the resource allocation information RA#l to #S (that is  including RA_SIZE#l to #S  RA_START#l to #S  and RA_PLACEMENT (CRU) to the terminal device MS#l to #S that perform the MU-MIMO transmission  which are determined by the terminal device allocator 107 
[0054] When RA_SIZE#l to #S included in the resource allocation information RA#l to #S is different from each other (including a case in which RA_START#l to #S is different even if RA_SIZE#l to #S is the same)  the additional data area setting section 111 detects an area including the minimum and the maximum of indexes of the LRU used for allocation to the
terminal device M#l to #8 that perform the MU-MIMO transmission as an MU-MIMO area  from RA_8TART#1 to #8 and RA_8IZE#1 to #8 information. That is  the MU-MIMO area ([start position  end position]) is defined by the following Exp ression (l). [0055] [Expression 1]
[~2 ~i{R.4 --SlilRT# n)  ~1~~{RA __ S1.""ART#n+ RA_"SIZE#n)] (1)
[0056] Further  the additional data area setting section 111 sets the additional data area that enables transmission with the additional data by the use of a partial resource of a resource area (hereinafter called "unfilled resource area RA_UNFILLED#n") in which the resource allocation area [RA_START#n  RA_START#n+RA_SIZE#n] to the terminal device MS#n (n=l to S in this example) is less than the MU-MIMO area. [0057] In this example  the additional data area is set on the basis of a value LRU_ADD#n that is integer-valued by multiplying the number of LRU included in the unfilled resource area RA_UNFILLED#n by a specific coefficient smaller than 1 (for example  1/2  113  2/3)  and rounding up  down  or off the multiplied result. [0058] An upper limit may be provided for the LRU_ADD#n so that when the LRU_ADD#n exceeds the upper limit  the LRU_ADD#n is replaced with the upper limit. As a result  when the unfilled resource area RA_UNFILLED#n is larger  the upper limit is set to the additional data area so that the quality of the spatial stream addressed to the M8#n can be prevented from being excessive. [0059] With above operation  the additional data area is set to an area continuous to the resource allocation area [RA...8TART#n  RA_STAR""Ttin + RA_8IZEtln] of the terminal device M8t1n in a range not exceeding the MU-MIMO area  on the basis of the LRU_ADDtln determined by the additional data area setting section 111. [0060] In this example  the additional data area is set by selecting one kind of pattern although there are the following three patterns (1) to (3) from a positional relationship between the resource allocation area and the MU_MIMO area of the terminal device MStin. [00611 As a setting pattern (l) of the additional data area  when an end position of the resource allocation area of the terminal device M8t1n matches anend position of the MU-MIMO area  the additional data area is set to an
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---:-¬
area continuous to [RA_START#n-LRU_ADD#n  RA_START#n-ll in the range not exceeding the MU-MIMO area_ [0062] As a setting pattern (2) of the additional data area  when a start position of the resource allocation area of the terminal device MS#n matches a start position of the MU-MIMO area  the additional data area is set to an area continuous to [RA_START#n+RA_SIZE#n+l  A_START#n+RA_SIZE#n+LRU_ADD#n] in the range not exceeding the MU-MIMO area  [0063] As a setting pattern (3) of the additional data area  when the start position and the end position of the resource allocation area of the terminal device MS#n do not match the start position and the end position of the MU-MIMO area  the additional data area is set to an area continuous to [RA_START#n-A  RA_START#n-l] and [RA_START#n+RA_SIZE#n+l  A_START#n+RA_SIZE#n+B] in the range not exceeding the MU-MIMO area  In this example  A and B are distributed so that A+B=LRU_ADD#n is met  [0064] Then  the additional data area setting section 111 outputs additional data area setting information that is set by anyone of the above-mentioned setting patterns  area information on the resource allocation area [RA_STAR""r#n  RA_START#n+RA_SIZE#nl to the terminal device MS#n including the additional data area  and allocation information RA_PLACEMENT (CRU) to an additional data generator 121  a resource allocation information generator 123  and the null data area setting section 113  [0065] The additional data per se is transmitted from the base station device 100 to the terminal device 200  by the use of the area exceeding the RA_SIZE#n from the start position of the finally determined area of the resource allocation area [RA_START#n  RA_START#n+RA_SIZE#nl including the additional data area (The detail will be described in the description of the operation of the additional data generator 121.)  [0066] Subsequently  a description will be given in detail of the operation of the additional data area setting section 111 when performing the MU-MIMO transmission to the four terminal devices MS#1 to MS#4 with reference to FIG  2  FIG  2 is a diagram illustrating a resource allocation status in performing MU-MIMO transmission  The axis of ordinate in FIG  2 represents an index of the spatial streams  and the axis of abscissa in FIG  2 represents a resource index (LRU index expression) of an LRU unit  Also 
in the figure  blocks not hatched represent the resource allocation areas allocated by the terminal device allocator 107  blocks hatched represent the additional data area  and areas (areas not included in the resource allocation areas and the additional data areas) not blocked which are indicated by arrows in the MU-MIMO area represent null data areas  [0067] In FIG  2  the MU-MIMO area is [1  S] (LRU index expression)  and expresses an example of setting the additional data area in the case of LRU _ADD#n=(lJ2)RA_ UNFILLED#n  [006S]
As illustrated in FIG  2  the start position of the resource allocation area of the terminal device MS#1 matches the start position #1 of the MU-MIMO area [1  S]. For that reason  the additional data area setting section 111 sets the additional data area in the setting pattern (2) of the additional data area  [0069] <""rerminal Devices MS#2  MS#4>
Also  as illustrated in FIG  2  the end positions of the resource allocation areas of the terminal devices MS#2 and MS#4 match the end position#S of the MU-MIMO area [1  S]  For that reason  the additional data area setting section 111 sets the additional data area in the setting pattern (1) of the additional data area  [0070] < Terminal Device MS#3>
Further  as illustrated in FIG  2  the start position and the end position of the resource allocation area of the terminal device MS#3 do not match the start position #1 and the end position #S of the MU-MIMO area [1  S]  For that reason  for that reason  the additional data area setting section III sets the additional data area in the setting pattern (3) of the additional data area  [0071] When the continuous mapping (CRU) is performed on a subband unit basis  configured by a given number ofPRUs continuous in a frequency domain  setting of the additional data area by the additional data area setting section 111 is performed so that the null data area becomes an integral multiple of the subband unit  This is because of the following reasons  [0072] When the continuous mapping (CRU) of the subband unit is performed  there is generally used a technique in which the channel estimation precision is improved by interpolating (averaging) the channel
estimation using a pilot symbol between the adjacent PRUs within the subband. FIG. 3 illustrates a channel estimation range based on the subband unit configured by four PRU#k  #k+1  #k+2  and #k+8 continuous in the frequency domain. Referring to FIG. 3  a channel estimation range (1) is used for the PRU#k and #k+1  and a channel estimation range (2) is used for the PRU#k+2 and #k+3 to perform the channel estimation. As a result  the channel estimation can be performed by using the pilot symbol included in the adjacent PRU  and an error in the channel estimation can be reduced. [0073] When the continuous mapping (CRU) of the subband unit as illustrated in FIG. 3 is performed  if the additional data area is set so that the null data area is less than the integral multiple of the subband unit  the subband including the data area (the resource allocation area or the additional data area) and the null data area is configured. In the data area  the pilot symbol is transmitted as usual. However  in a null data area signal generator 126 that will be described later  a signal for transmitting the pilot symbol as a null pilot (transmitting with a transmission power 0) is generated in the null data area. For that reason  in performing the channel interpolation between the PRUs spanning the data area and the null data area  a method of transmitting the pilot symbol is different between those areas. Therefore  an error in the channel estimation is increased. [0074] However  as described above  the additional data area setting section 111 sets the additional data area so that the null data area includes the area of the integral multiple of the subband unit. As a result  the channel interpolation is not performed between the PRUs spanning the data area and the null data area at the time of estimating the channel in the terminal device MS#n  thereby enabling an influence of the degradation of the channel estimation to be prevented. When a plurality of null data areas discontinuously exist in the MU-MIMO area as with the MS#3 in FIG. 3  the additional data area is set in each of the null data areas so as to provide an area of the integral multiple of the subband unit. [0075] The null data area setting section 113 sets the resource area (hereinafter called "null data area RA_NULLltn") that is less than the MU-MIMO area on the basis of the area information on the resource allocation area [RA_START#n  RA_START#n+RA_SIZE#n] to the terminal device MS#n (n=1 to S in this example) including the additional data area from the additional data area setting section 111. The MU-MIMO area is
detected with the use of information from the resource allocation information extractor 109 as with the additional data area setting section 111. [0076] The pilot sequence allocator 115 determines mapping of the pilot sequence to be transmitted together with the spatial stream to all of the terminal devices MS#l to #S that perform the MU-MIMO transmission  in other words  the number PSI (pilot stream index) of the pilot sequence. In this example  S represents the number of spatial multiplexing (the number of spatial multiplexing users). When the number of spatial multiplexing is S  a pilot sequence number (PSI  ; S) which is a natural number of S or lower is used. [0077] In FIG. 4  (a) and (b) are diagrams illustrating examples of mapping of the pilot sequence and mapping of the data series in two streams mapped to the subcarriers including a plurality of OFDM symbols. [0078] In FIG. 4(a)  symbols indicated by "I" are pilot symbols in the case of PS 1=1  square frames having no description are areas to which data symbols of the spatial streams transmitted together with the pilot sequence of PSI=l are allocated. In FIG. 4(b)  symbols indicated by "2" are pilot symbols in the case ofPS1=2  square frames having no description are areas to which data symbols of the spatial streams transmitted together with the pilot sequence ofPSI=2 are allocated. Also  in FIG. 4  at (a) and (b)  symbols indicated by "x" are null symbols  and the pilots are also time-frequency resources to which data is not also allocated. [0079] The different PSIs have a property having an orthogonal relationship to each other (anyone or combination of time  frequency  and code). In FIG. 4  PSI=l and PSI=2 are orthogonal to each other in the time-frequency resource. [0080] Subsequently  a description will be given of the individual control signal and individual data signal generator 120 configuring a part of the base station device 100 according to the first embodiment with reference to FIG. 1. The individual control signal and individual data signal generator
120 includes a plurality of individual control signal and individual data signal generators #1 to #S. [0081] Further  each of the individual control signal and individual data signal generators #1 to #S includes the additional data generator 121  a mode information/stream number information generator 122  the resource allocation information generator 123  an individual ID information generator
~ o~-~--:
:
124  a pilot sequence information generator 125  the null data area signal generator 126  an MCS information generator 131  an individual control signal generator 133  an encoder/modulator 135  an individual pilot adder 137  a precoding controller 139  and a beam-forming section 141. [0082] The individual control signal and individual data signal generator #S generates the individual control signal and individual data signal on the basis of the individual resource allocation information for the terminals output from the terminal device allocator 107  the individual additional data area setting information for the terminals output from the additional data area setting section 111  and the individual null data area setting information output from the null data area setting section 113 with respect to the terminal device MS#n. In this example  n=l to S. [0083]
Subsequently  a description will be given of a configuration related to the individual control signal generation and operation thereof in the configurations of the individual control signal and individual data signal generator #n below. [0084] The mode information/stream number information generator 122 extracts information on the presence or absence of the multiuser MIMO transmission to the terminal device MS#n allocated by the terminal device allocator 107  and also information on the total number of spatial multiplexing over the terminal devices in the multiuser MIMO mode  and generates the mode information/stream number information based on a given format. [0085] The individual ID information generator 124 extracts the individual ID information on the terminal device MS#n allocated by the terminal device allocator 107  and generates the individual ID information based on a given format. [0086] The pilot sequence information generator 125 extracts the pilot sequence allocation information for the terminal device MS#n from the pilot sequence allocator 115  and generates the pilot sequence information based on a given format. [0087] The MCS information generator 131 extracts information on the modulation multi-level value and the code rate of the error correcting cocle (hereinafter referred to as "MCS (modulation and coding scheme)") for the terminal device MS#n allocated by the terminal device allocator 107  and generates the MCS information based on a given format. [OOSS] The individual control signal generator 188 generates the individual control information based on a given format on the basis of outputs of the mode information/stream number information generator 122  the resource allocation information generator 123  the individual ID information generator 124  the pilot sequence information generator 125  and the MCS information generator 181. The individual control signal generator 133 subjects the generated individual control information on a given error detection coding process and an error detection code (CRC code) adding process  and subjects the individual control information on a given modulating process to form an individual control signal. [0089] The resource allocation information generator 123 extracts the resource allocation information for the allocated terminal device MS#n on the basis of the output of the additional data area setting section Ill  and generates the allocation information based on a given format. That is  when no additional data area is set by the additional data area setting section 111  the resource allocation information RA#n (that is  including RA_SIZE#n  RA3)TART#n  RA_PLACEMENT (CRU)) 
[0090] In this example  when the additional data area is set by the additional data area setting section Ill  the resource allocation information generated by the resource allocation information generator 123 includes RA_SIZE#n+LRU_ADD#n that is the size information  the start position information  and the allocation information RA_PLACEMENT (CRU)
[0091] The start position information that is one of the resource allocation information generated by the resource allocation information generator 123 is anyone of three kinds of patterns (1) to (3) stated below 
[0092] As a pattern (1) of the start position information  when the end position of the resource allocation area of the terminal device MS#n matches the end position of the MU-MIMO area  the start position information is
RA_START#n-LRU_ADD#n 
[0093] As a pattern (2) of the start position information  when the start position of the resource allocation area of the terminal device MS#n matches the start position of the MU-MIMO area  the start position information is
RA_START#n+RA_SIZE#n+1.
[0094] As a pattern (3) of the start position information  when the start
 
position and the end position of the resource allocation area of the terminal device MS#n do not match the start position and the end position of the MU-MIMO area  the start position information is RA_START#n-A [0095]
Subsequently  a description will be given of the configuration related to the individual data signal generation and operation thereof in the configurations of the individual control signal and individual data signal generator #n below_ [0096] The encoder/modulator 135 performs a coding process and a modulating process on the data (individual data) addressed to the terminal device MS#n allocated by the terminal device allocator 107 according to the code rate and the modulation multi-level value based on the MCS information from the MCS information generator 131 to generate symbol data addressed to the terminal device MS#n. [0097] The additional data generator 121 generates bit data according to additional parity bit or repetition bit on the basis of the adqitional data area information LRU ADD#n for the terminal device MS#n froin the additional data area setting section 111  and further performs a modulating process on the bit data through a modulation system based on the MeS information from the MeS information generator to generate additional data symbol data addressed to the terminal device MS#n. [0098] In this example  as a method of generating the additional data in the additional data generator 121  an example in which punctured coding such as turbo coding is used will be described below. [0099] Punctured coded data such as a turbo code that has been subjected to the error correction coding process in the encoder/modulator 135 is coded by a mother code rate (code rate 112 or 113) of the encoder once  and temporarily saved in a circular buffer. In this example  coded bit data including a systematic bit and a parity bit is saved in the circular buffer  and stored in the order of the systematic bit and the parity bit. [0100] The encoder/modulator 135 reads the systematic bit and the parity bit from the coded bit data saved in the circular buffer so as to provide the code rate instructed by the MCS information generator 131. [0101] In this case  the generation of the additional data in the additional data generator 121 reads  from the last position of the parity bit read by the
-~ ¬
encoder/modulator 135  a follow"on parity bit. The number of read bits is as large as a value (JxD) obtained by multiplying the number of data symbols D indicated by the additional data area information LRU_ADD#n by the number of bits per the modulation symbol in the modulation system instructed by the MCS information generator 131  that is  J bits. In this example  when the read position is a termination position of the circular buffer  the read position returns to a head position of the circular buffer  and the bits are again read from the systematic bit. [0102] The additional data generator 121 generates a modulation symbol by using the same modulation system as the modulation system in the encoder/modulator 135 with respect to the additional bit obtained in the above"mentioned method. With the above operation  the additional data generator 121 can generate the symbol data to be transmitted with the use of the additional data area information LRU_ADD#n. [0103] The individual pilot adder 137 adds the individual pilot signal to the symbol data that are outputs of the encoder/modulator 135 and the additional data generator 121 of the terminal device MS#non the basis of the information from the pilot sequence information generator 125. [0104] In this example  the symbol data is arranged in the order of the output symbol data of the encoder/modulator 135 and the output symbol data of the additional data generator 121 as one output. As a result  even if the additional data symbol exists  the receiving process can be performed by the terminal device without any additional control information. This is because  in the additional data generator 121  the output symbol data of the encoder/modulator 135 and the output symbol data of the additional data generator 121 are symbol data generated from continuous bit data on the circular buffer.
[0105] The pilot sequence uses a known signal orthogonal between the series by using time division multiplexing  frequency division mUltiplexing  or code division multiplexing on an OFDM subcarrier basis. As a result  the terminal device can receive the signal while suppressing interference between the spatial streams  thereby being capable of improving a channel estimation precision of the MIMO propagation channel using the individual pilot signal. [0106] The null data area signal generator 126 generates a signal in the null data area on the basis of the information on the null data area RA_NULL#n
for the terminal device MS#n (n=l to S in this example)  That is  the symbol data of the LRU included in the null data area RA_NULL#n of the spatial stream #n addressed to the terminal device MS#n generates a signal of the null data with a transmission power of 0  Also  the individual pilot symbol included in the null data area generates the signal of the null pilot with the transmission power of 0  [0107] The precoding controller 139 extracts the precoding weight information for the terminal device MS#n allocated by the terminal device allocator 107  and controls a precoding weight Vt in the subsequent beam-forming section 141 on the basis of the precoding information  [0108] The beam-forming section 141 multiplies a signal xs in which the individual pilot signal is added to the symbol data addressed to the terminal device MS#n  which is output from the individual pilot adder 137  by the precoding weight Vt  and outputs data wjxs for the number of transmission antennas (Nt)  In this example  when the number of transmission antennas is Nt  a transmission weight vector Vt is expressed by an Nt-order column vector having Nt vector elements wj  In this example  j=l  "" Nt  [0109] The OFDMA frame-forming section 151 maps the individual data signal addressed to the terminal device MS#n and the individual control signal addressed to the terminal device MS#n for the number of transmission antennas (Nt)  which are output from the beam-forming section 141  to the subcarrier (physical resource unit PRU) within a given OFDMA frame on the basis of the resource allocation information output from the resource allocation information generator 123  and outputs the mapped signals to the IFFT sections 153  [0110] In this example  mapping of the individual data signal to the physical resource unit PRU is mapped to the PRU on the basis of the area information on the resource allocation area [RA_START#n  RA_START#n+RA_SIZE#n] for the individual data addressed to the terminal device MS#n indicated by the LRU index including the additional data area  and allocation information (CRU)   In this example  FIG  5 illustrates an example of mapping to the
PRU  CRt) [0111] In this embodiment  because only the continuous mapping (~is dealt with as the allocation information  the OFDMA frame-forming section 151 maps each of the LRU#1 to LRU#4 to each sub carrier of the PRU#l to LRU#4 as illustrated in FIG  5  That is  the OFDMA frame-forming section
151 maps one LRU to the subcarrier within one PRU.
[0112] In this example  the output from the beam-forming section 141 is symbol information in which the individual pilot is added to the LRU data  and includes the pilot symbol and the data symbol included in the PRU. The symbol information is allocated to a data symbol mapping portion and a pilot mapping portion in the PRU in a given order_ [0113] Further  the OFDMA frame-forming section 151 maps the null symbol data output from the null data area signal generator 126 to the PRU on the basis of LRU index information indicated by the null data area information  which is output from the null data area setting section 113  [0114] The individual control signal is transmitted without being formed into a beam  but in this situation  a transmission diversity technique such as a CDD  an STBC  or an SFBC is applied to enable an improvement in the reception quality. [0115] The IFFT sections 153 performs an IFFT process on the respective outputs of the Nt OFDMA frame-forming section 151  and adds and outputs a given cyclic prefix (or guard interval)  [0116] The transmitters 155 converts a baseband signal from the IFFT sections 153 into a high frequency signal of a carrier frequency band  and outputs the high frequency signal from the base station antenna  [00117] Subsequently  a description will be given of a configuration of the terminal device 200 according to the first embodiment with reference to FIG  6  FIG  6 is a block diagram illustrating a configuration of the terminal device 200 according to the first embodiment  The terminal device 200 illustrated in FIG  6 includes a plurality ofreception antennas 201  a plurality of receivers 203  a control information extractor 205  a channel estimator 207  an MIMO receiving processor 209  a decoder 211  a precoding weight selector and reception quality estimator 213  a feedback information generator 215  a transmitter 217  and a transmission antenna 219  [Ol1S] The plurality ofreception antennas 201 receive the high frequency signal from the base station device 100  [0119] The plurality of receivers 203 convert the high frequency signals received by the respective reception antennas 201 into the baseband signals  The signal processed by each of the receivers 203 is output to the control information extractor 205  the channel estimator 207  and the MIMO receiving processor 
 
[0120] The control information extractor 206 detects an individual control signal addressed to a own terminal device  including the individual ID information on the own terminal device from the individual control signals notified of from the base station device 100. Then  the control information extractor 206 of the terminal device 200 extracts the resource allocation information  the MCS information  and the mode information  which are control information included in the individual control signal addressed to the own terminal device. Further  when the extracted mode information is indicative of a mode for performing the multiuser MIMO transmission  the control information extractor 206 extracts stream number inform a tion and pilot sequence information. [0121] The channel estimator 207 extracts a common pilot signal to be periodically transmitted together with the control information signal from the base station device 100  and calculates a channel estimate value. [0122] Also  in the multiuser MIMO transmission mode  the channel estimator 207 extracts the individual pilot signal allocated by the PSI for the number of spatial streams (Mt) included in the resource to which the spatial stream is allocated  on the basis of the spatial stream information Mt and the resource allocation information  which are included in the individual control information at the time of the multiuser MIMO transmission  and performs the channel estimation of the MIMO propagation channel. [0123] In this example  when the number of spatial streams is Mt  the channel estimator 207 extracts the individual spatial streams allocated by PSI=l to Mt  which are included in the Mt spatial streams  and performs the channel estimation. When the number of reception antennas is Mr  a channel matrix H representative of the MIMO propagation channel includes an element h(n  m) ofMr x Mt. In this example  n=l  ...   Mr  m=l  ...   Mt  and h(n m) represents a channel estimate value when an moth spatial stream (that is  a spatial stream including the pilot sequence ofPSI=m) is received by an n-th reception antenna.
[0124] When the individual control signal that performs the multiuser MIMO transmission  which is transmitted to the terminal device MS#n  is included in the control information extracted by the control information extractor 205  the MIMO receiving processor 209 performing the MIMO receiving process on the spatial stream that is subjected to the multiuser MIMO transmission  on the basis of the control information included in the
individual control signal and a channel estimated result H from the channel estimator 207. The MIMO receiving process uses a linear receiving process using an inverse matrix of a channel matrix such as an MMSE or ZF (zero forcing) on the basis of the channel estimated result H  the pilot sequence information PSI for the spatial stream addressed to the own terminal device  and the modulation information included in the MCS information. [0125] The decoder 211 performs a decoding process on the basis of the output of the MIMO receiving processor 209. [0126] The precoding weight selector and reception quality estimator 213 selects a precoding weight highest in reception quality from several precoding weight candidates on the basis of the channel estimate value calculated in the channel estimator 207. Further  the precoding weight selector and reception quality estimator 213 estimates the reception quality of the selected precoding weight. Then  the precoding weight selector and reception quality estimator 213 outputs the selected precoding weight selection information and the estimated result of the reception quality to the feedback information generator 215. [0127] The feedback information generator 215 generates a data series of a given format in order to report the output of the precoding weight selector and reception quality estimator 213 to the base station device 100 as feedback information. [0128] The transmitter 217 transmits the data series generated by the feedback information generator 215 in order to report the data series to the base station device 100 as the feedback information. [0129] In the terminal device 200 according to this embodiment  the reception antennas 201 and the transmission antenna 219 are dealt with as separate parts  but the same antenna may be shared. Also  a plurality of the• transmission antennas 219 and a plurality of the transmitters 217 may be :provided to perform directional transmission. [0130] Subsequently  a description will be given of a processing procedure between the base station device 100 and the terminal device 200 in the first embodiment with reference to FIG. 7. FIG. 7 is a diagram illustrating a processing procedure between a base station device 100 and the terminal device 200 according to the first embodiment. [0131] In Step Sl  the base station device 100 periodically transmits the pilot signal (common pilot signal) not multiplied by the precoding weight
together with the control information signal. [0132] In Step S2  the terminal device 200 extracts the common pilot signal  and calculates the channel estimate value in the channel estimator 207. [0133] In Step S3  the terminal device 200 selects the precoding weight highest in reception quality from the several precoding weight candidates on the basis of the channel estimate value estimated in the precoding weight selector and reception quality estimator 213  and estimates the reception quality in this situation. [0134] In Step S4  the terminal device 200 generates a data series of a given format in order to report the output of the precoding weight selector and reception quality estimator 218 to the base station device 100 as the feedback information in the feedback information generator 215. [0135] In Step S4A  the terminal device 200 converts the baseband signal into the high frequency signal  and outputs the high frequency signal from the transmission antenna 219 in the transmitter 217. [0186] In Step S5  the base station device 100 performs the allocation of the terminal device 200 that performs the multiuser MIMO transmission in the terminal device allocator 107. Then  in Step S5A  the base station device 100 transmits the individual control information for notifying the allocation of the terminal device 200 that performs the multiuser MIMO transmission to the terminal device 200  [0187] In Step S6  the terminal device 200 detects the individual control signal addressed to the own terminal device in the individual control signals notified offrom the base station device 100 in the control information extractor 205  Then  the terminal device 200 extracts the resource allocation information  the MCS information  and the mode information which are the control information included in the individual control information addressed to the own terminal device. When the extracted mode information is indicative of a mode for performing the multiuser MIMO transmission  the terminal device 200 further extracts the stream number information and the pilot sequence information 
[0138] In Step S7  the base station device 100 generates the individual data signals and the individual pilot signals for the number oftransmission antennas (Nt)  [0139] In Step S7A  the base station device 100 transmits the individual control signal to the terminal device 200  and thereafter transmits the
individual data signal. [0140] In this example  the terminal device 200 performs processing in Steps S8 and S9 with the use of the individual control addressed to the own terminal device extracted by the control information extractor 205. [0141] In Step S8  the terminal device 200 performs the channel estimation of the MIMO propagation channel in the channel estimator 207. [0142] In Step S9  the terminal device 200 performs an error correction decoding process of the individual data signal received from the base station device 100 in Step S7A with the use of the code rate information on the error correcting code included in the MCS information for the spatial stream addressed to :he own terminal device  and the output of the MIMO receiving"" processor 209 in the decoder 211. [0143] As described above  in this embodiment  in the terminal device allocator 107 of the base station device 100  when theterminal device 200 not identical in the allocation resource size is allocated as a simultaneous multiplexing user at the time of the MU-MIMO transmission to reduce addition ofscheduling so that the flexibility of the MU-MIMO allocation can be enhanced. [0144] Also  in this embodiment  the base station device 100 transmits an additional parity bit (or repetition bit) to a part of a portion that is less than the MU-MIMO area  thereby enabling the reception quality of the user having small allocation resource to be improved. [0145] Also  in this embodiment  the base station device 100 uses the null data area for a part of the portion that is less than the MU-MIMO area  thereby enabling the same channel interference between the spatial multiplexing streams to be reduced. As a result  the reception quality of the users other than the user having small allocation resource can be also improved.
[0146] Also  in this embodiment  the base station device 100 sets the pilot in the null data area as the null pilot  thereby enabling the reception weight reflecting that the number of spatial streams is reduced in the null data area to be generated in the terminal device 200. As a result  the reception diversity effect can be enhanced to enable a remarkable improvement in the reception quality. [0147] From the advantages of the above-mentioned embodiment  in this embodiment  a bias of the reception quality between the spatial streams
;----¬
which perform the MU-MIMO is suppressed so that the overall quality of the spatial streams can be improved. [0148] [Modified Example of Base Station Device 100]
In this example  the base station device 100 according to the first embodiment has a configuration using the continuous mapping (CRU) as the resource allocation method  and uses the additional data area and the null data area  to thereby entirely improve the reception quality of the spatial streams between the terminal devices different in the resource size. However  the present invention is not limited to this configuration. In a base station device 100A according to a first modified example of the base station device 100 of the first embodiment  when the resource allocation is the continuous mapping (CRU)  the transmission power is changed for each stream so that the reception quality of the entire streams that perform the MU-MIMO transmission can be improved. [0149] Hereinafter  a configuration of the base station device 100A will be described with reference to FIG. 8. FIG. 8 is a block diagram illustrating the configuration of the base station device 100A. The base station device 100A illustrated in FIG. 8 includes the plurality of antennas 101 configuring the base station antenna  the receiver 103  the feedback information extractor 105  the terminal device allocator 107  the resource allocation information extractor 109  the additional data area setting section 111  the pilot sequence allocator 115  an individual control signal and individual data signal generator 120A  the OFDMA frame-forming section 151  the plurality ofIFFT sections 153  and the plurality of transmitters 155. [0150] Also  each of individual control signal and individual data signal generators #1 to #8 configuring the individual control signal and individual data signal generator 120A includes the additional data generator 121  the mode information/stream number information generator 122  the resource allocation information generator 123  the individual ID information generator 124  the pilot sequence information generator 125  the spatial stream power controller 143  the MC8 information generator 131  the individual control signal generator 133  the encoder/modulator 135  the individual pilot adder 137  the precoding controller 139  and the beam-forming section 14l. [0151] Differences of the base station device 100A illustrated in FIG. 8 from the base station device 100 according to the first embodiment illustrated in
;--""-¬
. -""
FIG. 1 reside in that the additional data area setting section 111 is replaced with an additional data area setting section 111A  and the null data area setting section 113 and the null data area signal generator 126 are replaced with the spatial stream power controller 143 provided in the individual control signal and individual data signal generator 120A. The other configurations are common to those in the base station device 100  and the common configurations are denoted by identical reference symbols  and their detailed description will be omitted. [0152] In the base station device 100A  instead of the use of the null data area  the spatial stream power controller 143 makes the transmission power between the spatial streams variable so that the reception quality of the spatial streams between the terminal devices different in the resource size can be entirely improved. [0153] Hereinafter  a description will be given of a configuration of the base station device 100A different from the base station device 100 according to the first embodiment illustrated in FIG. 1. [0154] When the RA SIZE#l to #S included in the resource allocation information RA#l to #S are different from each other (further  including a case in which RA_START#l to #S are different from each other even when RA SIZE#l to #S are identical with each other)  the additional data area setting section 111A detects an area including a minimum value and a maximum value of the indexes of the LRU used for allocation to the terminal devices MS#l to #S that perform the MU-MIMO transmission as the MU•MIMO area from RA.J)TART#l to #S and RA_SIZE#l to #S information. That is  the MU-MIMO area is defined by the following Expression (2) [0155] [Expression 2]
ff~ tg(RA.. STARl""fln)""l2;z;(RA_S""J""ARTNn + RA.. SIZE#nl] (2)
[0156] Further  the additional data area setting section 111A sets the additional data area for transmitting the additional data with the use of all of the resources in the resource area (hereinafter called "unfilled resource area RA_UNFILLED#n") where the resource allocation area [RA_START#n  RA_START#n+RA_SIZE#nJ for the terminal device MS#n (n=l to S in this example) is less than the MU-MIMO area.
[015.7] Then  the additional data area setting section outputs the additional data area setting information set as described above  the area information on
;""--¬
the resource allocation area [RA_START#l to #n  RA_START#n+RA_SIZE#n] for the terminal device MS#n including the additional data area  and the allocation information RA_PLACEMENT (CRU) to the additional data generator 121  the resource allocation information generator 123  and the spatial stream power controller 143  [0158] The spatial stream power controller 143 controls the transmission power of the spatial streams on the basis of the setting status of the additional data area  That is  because the additional data area is set for the spatial streams of the terminal device in which the resource size is smaller than the MU-MIMO area  an improvement of the reception quality due to the additional data is estimated to control the transmission power to be reduced  On the other hand  the spatial stream power controller 143 performs a control for increasing the transmission power for the spatial streams of the terminal device in which the resource size is identical with or substantially equal to the MU-MIMO area  [0159] A description will be given of an example of the transmission power control of the entire MU-MIMO area by the spatial stream power controller 143 with reference to FIGS  9 and 10  FIG  9 is a diagram schematically illustrating a transmission power control example (1) of the spatial stream power controller 143  and FIG  10 is a diagram schematically illustrating a transmission power control example (2) of the spatial stream power controller 143  The axis of ordinate in FIGS  9 and 10 represents the indexes of the spatial streams  and the axis of abscissa in FIGS  9 and 10 represents a release index (LRU index expression) of the LRU basis  [0160] Also  hatched blocks in the figures represent the additional data areas  Also  ranges of both arrows indicated at the right of the axis of ordinate in FIGS  9 and 10 schematically represent magnitudes P#l and P#2 of the transmission powers for the respective indexes #1 and #2 of the spatial streams  That is  as the spatial streams are larger in the ranges of both the arrows indicated at the right of the axis of ordinate in FIGS  9 and 10  the"" transmission powers are larger  [0161] As illustrated in FIG  8  the spatial stream power controller 143 performs a control for increasing the transmission power P#l on the spatial stream of the terminal device MS#l in which the resource size is substantially equal to the MU-MIMO area 
[0162] Also  as illustrated in FIG  9  because the additional data area is set
for the spatial stream ofthe terminal device MS#2 in which the resource size is smaller than the MU-MIMO area  an improvement in the reception quality due to the additional data is estimated. Then  the transmission power is reduced for the LRU including the additional data area to set the transmission power P#2. [0163] As illustrated in FIGS. 8 and 9  the transmission power control of the entire MU-MIMO area is performed on the LRU basis while the individual pilot signal and the transmission powers of the individual data are kept equal to each other or at a predetermined power ratio. As a result  the data can be demodulated without providing an additional control signal. [0164] As described above  in the base station device 100A according to the modified example of the first embodiment  (1) the user stream small in the resource size uses the additional data area  and the transmission power is reduced  whereby (2) the transmission power is increased and distributed as large as the reduced transmission power with respect to the stream of another user  to thereby enable the reception quality to be improved. [0165] (Second Embodiment)
The first embodiment is described in a case where a decision is made that the terminal device allocator 107 of the base station device 100 uses only the continuous mapping (CRU) as the allocation method (RA PLACEMENT). However  in the first embodiment  when the distributed mapping (DRU) is also used as the allocation method (RA_PLACEMENT)  the LRU in the null data area is distributed in a plurality of PRUs. For that reason  when it is assumed that the pilot signal in the null data area is the null pilot signal  data out of the null data area is included in the PRU  and the channel estimate precision in modulating the data may be degraded. [0166] FIG. 11 illustrates an appearance in which when LRU#4 is the null data area  the LRU#4 is distributed into a plurality ofPRU#l to #4 as the PRD. As illustrated in FIG. 11  the LRU#4 of the null data area is distributed into the plurality of PRU#l to #4 as the PRU by a sub carrier interleaver (or tone permutation). Because the pilot signal is used for modulation of data out of the null data area  there is a need to transmit the pilot signal in the null data area as usual. However  when the CRU is used  the pilot signal in the null data area is set as the null pilot signal  as a result of which not only the same channel interference between the spatial
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multiplexing streams is reduced  but also the effect of improving the remarkable reception quality can be obtained by enhancing the reception diversity effect  [0167] In order to prevent the channel estimation precision from being degraded when the distributed mapping (DRU) is used as the allocation method (RA_PLACEMENT)  a base station device 300 according to the second embodiment newly includes  in addition to the configuration of the base station device 100 according to the first embodiment  a resource allocation method detector 301 that detects whether the resource allocation is the distributed mapping or the continuous mapping according to the resource allocation information  and a pilot transmission controller 302 that controls a pilot transmitting method to set the pilot signal in the null data area setting section 113 to the null pilot or the normal pilot transmission on the basis of the detection result of the resource allocation method detector  [0168] FIG  12 illustrates a configuration of the base station device 300 according to this embodiment  FIG  12 is a block diagram illustrating a configuration of the base station device 300 according to the second embodiment. The base station device 300 illustrated in FIG  12 includes the plurality of antennas 101 configuring the base station antenna  the receiver 103  the feedback information extractor 105  the terminal device allocator 107  the resource allocation information extractor 109  the additional data area setting section 111  the null data area setting section
113  the resource allocation method detector 301  the pilot transmission controller 302  an individual control signal and individual data signal generator 320  the OFDMA frame-forming section 151  the IFFT sections 153  and the plurality of transmitters 155  [0169] Differences of the base station device 300 illustrated in FIG  12 from the base station device 300 according to the first embodiment illustrated in FIG  1 reside in that the resource allocation method detector 301 and the pilot transmission controller 302 are additionally provided  and the individual control signal and individual data signal generator 120 is replaced with the individual control signal and individual data signal generator 320  Configurations common to those in the first embodiment are denoted by identical reference symbols  and their detailed description will be omitted  [01 70] Also a difference of the individual control signal and individual data signal generator 320 illustrated in FIG  12 from the individual control signal
and individual data signal generator 120 illustrated in FIG. 1 resides in that the null data area signal generator 126 is replaced with a null data area signal generator 326 different in the operation from the null data area signal generator 126. Configurations common to those in the first embodiment are denoted by identical reference symbols  and their detailed description will be omitted. [0171] The resource allocation method detector 301 further extracts only RA PLACEMENT (CRUIDRU) from the resource allocation information RA#l to #S (that is  including RA_SIZE#l to #S  RA_START#l to #S  RA_PLACEMENT (CRUIDRU)) extracted from the resource. allocation information extractor 109. The resource allocation method detector 301 then detects whether the resource allocation is the distributed mapping (DRU) or the continuous mapping (CRU). [0172] The pilot transmission controller 302 controls the pilot transmitting method to set the pilot signal in the null data area signal generator 326 to the null pilot or the normal pilot transmission. [0173] That is  when it is detected by the resource allocation method detector 301 that the resource allocation is the continuous mapping (CRU)  the pilot transmission controller 302 controls the pilot transmitting method to set the pilot signal in the null data area signal generator 326 to the null pilot. The null pilot is a pilot signal in which the transmission power of the pilot signal is O. In other words  when the resource allocation is the continuous mapping (CRU)  the pilot signal in the null data area is not transmitted. [0174] Further  when it is detected by the resource allocation method detector 301 that the resource allocation is the distributed mapping (DRU)   the pilot transmission controller 302 controls the pilot transmitting method to set the pilot signal in the null data area signal generator 326 to the normal pilot transmission. In other words  when the resource allocation is the distributed mapping (DRU)  the base station device 300 transmits the normal pilot signal in the null data area. [0175] The null data area signal generator 326 generates the signal of the null data area on the basis of information on the null data area RA_NULL#n for the terminal device MS#n (n=l to S). That is  the null data area signal generator 326 generates the symbol data of the LRU included in the null data area RA_NULL#n of the spatial stream #n addressed to the terminal
device MS#n as a signal of the null data in which the transmission power is 0 Also  the null data area signal generator 326 generates the individual pilot symbol included in the null data are a as the pilot signal on the basis of the control information of the pilot transmission controller 302. [0176] As described above  in this embodiment  the base station device 300 can control the pilot transmitting method in the null data area on the basis of the resource allocation method. For that reason  the base station device 300 can suppress the degradation of the reception characteristic due to the degradation of the channel estimation precision in the terminal device. Further  the use of the additional data area improves the quality of the spatial stream  and also the use of the null data area reduces the interference of the spatial stream addressed to another user. This can enhance the reception quality of all the spatial multiplexing streams that perform the MU-MIMO transmission in the terminal device. [0177] (Third Embodiment)
In the second embodiment  a description is given of fl. case in which the continuous mapping (CRU) and the distributed mapping (DRU) are used as the resource allocation method. However  when the base station device 300 according to the second embodiment is applied to the terminal device to which the MLD receiving system is applied in order to enhance the MIMO
. reception quality  there arises the following problems. [0178] The base station device 300 transmits only the pilot signal without transmitting data in the null data area. In this example  the terminal device that includes data addressed to the own terminal device in the null data area performs the MLD reception including the null data area. In this case  the pilot signal in the null data area is transmitted by not the null pilot but the normal transmission power. However  because data to be transmitted is the null data  the terminal device that performs the MLD reception generates an erroneous reception replica  and largely degrades the reception characteristic in the MLD receiving process. FIG. 13 schematically illustrates the resource allocation status in a two-user MU-MIMO mode. The axis of ordinate in FIG. 13 represents an index of the spatial streams  and the axis of abscissa in FIG. 13 represents a resource in""dex (LRU index expression) of an LRU basis. Also  blocks hatched in the figure represent the additional data area  and areas not blocked which are indicated by arrows in the MU-MIMO area represent the null data areas.
  ¬
Also  it is assumed that the terminal device MS#l is the MLD reception compliant terminal device. [0179] In the resource allocation status illustrated in FIG. 13  when the resource allocation is the distributed mapping (DRU)  the pilot signal in the null data area of the terminal device MS#2 is transmitted by not the null pilot but the normal transmission power. However  because data to be transmitted is the null data  the terminal device #1 that performs the MLD reception generates an erroneous reception replica  and erroneously generates the replica at the time of the MLD reception during the MLD recelVmg process. For that reason  the reception characteristic is largely degraded. On the other hand  in the case of the continuous mapping (CRU)  in order that the null pilot signal is transmitted together with the null data in the null data area ofthe terminal device MS#2  even ifthe terminal device MS#l performs the MLD reception  the characteristic is not degraded. Conversely  because the number of replica candidates is reduced  the characteristic of the MLD reception is improved. [0180] In the third embodiment  a description will be given of a configuration of a base station device 500 and a configuration of a terminal device 600 for suppressing the degradation of the MLD reception characteristic at the terminal device that performs the MLD reception. [0181] FIG.. 14 is a block diagram illustrating the configuration of the base station device 500 according to the third embodiment. The base station device 500 illustrated in FIG. 14 includes the receiver 103  the feedback information extractor 105  the terminal device allocator 107  the resource allocation information extractor 109  the additional data area setting section 111  the null data area setting section 113  a repetition symbol data area signal generator 503  an individual control signal and individual data signal generator 520  the OFDMA frame-forming section 151  the plurality of IFFT sections 153  and the plurality of transmitters 155. [0182] Differences of the base station device 500 illustrated in FIG. 14 from the base station device 300 illustrated in FIG. 12 reside in that the repetition symbol data area signal generator 503 is newly provided in addition to the configuration of the base station device 300 according to the second embodiment  the pilot transmission controller 302 is replaced with a data transmission controller 502  and the resource allocation method detector 301 is replaced with a resource allocation method detector 501. The other
-0_-_  -"" _ 
configurations are identical with those in the second embodiment  and in FIG. 4  components common to those in FIG. 12 are denoted by identical reference symbols. [0183] The repetition symbol data area signal generator 503 generates a signal of the known repetition symbol data area on the basis of the information on the null data area RA_NULL#n for the terminal device MS#n (1=1 to S in this example). That is  the symbol data of the LRU included in the null data area RA_NULL#n of the spatial stream #n addressed to the terminal device MS#n generates a signal of the symbol data using the same modulation system as that of the additional data area on the LRU basis. [0184] Also  the individual pilot symbol included in the repetition symbol data area generates the normal pilot signal. FIG. 15 schematically illustrates the resource allocation status including the repetition symbol data area in the two-user MU-MIMO mode. The axis of ordinate in FIG. 15 represents an index of the spatial streams  and the axis of abscissa in FIG. 15 represents a resource index (LRU index expression) of the LRU basis. Also  blocks hatched in the figure represent the additional data area  and areas not blocked which are indicated by arrows in the MU-MIMO area represent the null data areas. Also  it is assumed that the terminal device MS#1 is the MLD reception compliant terminal device. [0185] As illustrated in FIG. 15  in the spatial stream addressed to the terminal device MS#2  the signal of the symbol data using the same modulation system as that of the additional data area on the LRU basis is generated in the known repetition symbol data area. [0186] The data transmission controller 502 is configured to switch between an output of the null data area signal generator 326 and an output of the repetition symbol data area signal generator 503 through a switch 304 on the basis of the detection result of the resource allocation method detector 301  and output a selected output to the beam-forming section. That is  the data transmission controller 502 controls the pilot transmitting method to set the pilot signal in the null data area signal generator 326 to the null pilot or the normal pilot transmission on the basis of the detection result of the resource allocation method detector 301. [0187] When the resource allocation is the continuous mapping (CRU)  the data transmission controller 502 controls an output of the null data area signal generator 326 to be input to the individual control signal and
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individual data signal generator 520. On the other hand  when the resource allocation is the distributed mapping (DRU)  the data transmission controller 502 controls an output of the repetition symbol data area signal generator 503 to be input to the individual control signal and individual data signal generator 520. [0188] Subsequently  a description will be given of a configuration of the terminal device 600 according to the third embodiment with reference to FIG.
16. FIG. 16 is a block diagram illustrating the configuration of the terminal device 600 according to the third embodiment. The terminal device 600 illustrated in FIG. 16 includes the plurality of reception antennas 201  the plurality of receivers 203  the control information extractor 205  the channel estimator 207  the MIMO receiving processor 609  the decoder 211  the precoding weight selector and reception quality estimator 213  the feedback information generator 215  the transmitter 217  and the transmission antenna 219. A difference of the terminal device 600 illustrated in FIG. 16 from the terminal device 200 according to the first embodiment illustrated in FIG. 6 resides in the MIMO receiving processor 609  and the other configurations are identical with those of the terminal device 200. Configurations common to those in the first embodiment are denoted by identical reference symbols  and their detailed description will be omitted. [0189] The terminal device 600 according to this embodiment can improve the MLD reception quality during the MLD receiving process in the repetition symbol data area through the processing of the MIMO receiving processor 609. Hereinafter  a configuration of the MIMO receiving processor 609 will be described in detail with reference to FIG. 17. FIG. 17 is a block diagram illustrating a configuration of the MIMO receiving processor 609. The MIMO receiving processor 609 illustrated in FIG. 17 includes an LRU basis symbol data converter 621  an MLD processor 622  a repetition symbol area matching""detector 623  a known symbol memory 624  and a repetition symbol area decider 625.
[0190] The LRU basis symbol data converter 621 permutates data of the PRU basis into data of the LRU basis on the basis of output data of the receivers 203 for each of the reception antennas 201  and outputs data of the LRU basis to the MLD processor 622. [0191] The MLD processor 622 performs MLD processing on the basis of a channel matrix H that is an output from the channel estimator 207  the pilot
-:--~-""
sequence information PSI for the spatial stream addressed to the own terminal device or another terminal device  which is an output from the control information extractor 205  and the modulation information included in the MCS information. The MLD receiving process may use  for example  a technique disclosed in Non-patent Literature 4. Then  the MLD processor 622 outputs a soft decision value of the LRU basis of all the spatial streams to be subjected to the multiuser transmission to the decoder 211 and the repetition symbol area matching-detector 623. [0192] The known symbol memory 624 stores the known repetition symbol in a given period. The repetition symbol is output to the repetition symbol area matching-detector 623. [0193] The repetition symbol area matching-detector 623 converts the soft decision value output from the MLD processor 622 into a hard decision value. Then  the repetition symbol area matching-detector 623 detects a consistency of the hard decision value and the output from the known symbol memory 624. Then  the repetition symbol area matching-detector 623 outputs the detection result to the repetition symbol area decider 625. [0195] When the repetition symbol area matching-detector 623 detects that the consistence of the hard decision value and the output from the known symbol memory 624 is a given value or more  the repetition symbol area decider 625 outputs the decision result to the MLD processor 622 as the null symbol area. [0195] When the repletion symbol area is included in a part (Yk) of the spatial streams (Yl  Y2  ...   Y s)  the MLD processor 622 generates a replica in which the symbol ofYk is decided at the time of generating the replica in the MLD processor 622 on the basis of the decision result from the repetition symbol area decider 625  and performs the MLD processing for estimating the symbol of the remaining undecided spatial streams with the use of the maximum likelihood estimation standard. [0196] The terminal device 600 according to the third embodiment can improve the MLD reception characteristic by reducing the number of reception candidates through the above-mentioned MLD receiving process. [0197] As described above  in this embodiment  when the user not identical in the allocation resource size is allocated to the multiuser MIMO user  the base station device 500 sets  (1) when the resource allocation is the continuous mapping (CRU)  the additional data area for transmitting the
additional parity bit (or repetition bit)  and the remaining area as the null data areas with respect to a part of a portion that is less than the MU-MIMO area through the spatial stream of the user in which the allocation resource size is less than the MU-MIMO area  and sets  (2) when the resource allocation is the distributed mapping (DRU)  "additional data area" for transmitting the additional parity bit (or repetition bit)  and "repetition symbol area" for transmitting the known identical symbol on the LRU basis  on the LRU basis  respectively. As a result  even if the resource allocation is anyone of the continuous mapping (CRU) and the distributed mapping (DRU)  the reception characteristic is prevented from being largely degraded by generation of the erroneous reception replica during the AMLD receiving process. Further  the user of the additional data area improves the quality of the spatial stream. Also  the null data area is used when the resource allocation is the continuous mapping  or the repetition symbol area is used when the resource allocation is the distributed mapping. As a result  with application of the MLD receiving method that reduces the interference of the spatial stream addressed to another user or reduces the reception replica  the reception quality of all the spatial multiplexing streams that perform the MU-MIMO transmission in the terminal device can be enhanced. Hence  the reception quality of all the spatial multiplexing streams that perform the MU-MIMO transmission in the terminal device 600 can be enhanced. [0198] Further  in this embodiment  in the terminal device allocator 107 of the base station device 500  the base station device 500 not identical in the allocation resource size is allocated as the simultaneous multiplexing user during the MU-MIMO transmission  thereby being capable of reducing a load of scheduling  and enhancing the flexibility of the MU-MIMO allocation.
[0199] Also  in this embodiment  the base station device 500 transmits the additional parity bit (or the repetition bit) to a part of a portion that is less than the MU-MIMO area  thereby enabling the reception quality of the user having small allocation resource to be improved. [0200] Also  in this embodiment  when the resource allocation is the continuous mapping (CRU)   the base station device 500 uses the null data area for the spatial multiplexing stream  thereby enabling the same channel interference between the spatial multiplexing streams to be reduced. [0201] Also  in this embodiment  when the resource allocation is the continuous mapping (CRU)  the base station device 500 sets the pilot of the
.   ¬
null data area as the null pilot so that the reception diversity effect can be enhanced in the terminal device 600  to enable a remarkable improvement in the reception quality. [0202] Also  in this embodiment  when the resource allocation is the continuous mapping eCRU)  the base station device 500 can control the pilot transmitting method in the null data area on the basis of the resource allocation method. For that reason  the degradation of the reception characteristic attributable to the degradation of the channel estimation precision in the terminal device 600 can be suppressed. [0203] [First Modified Example of Terminal Device 600]
In the third embodiment  in the base station device 500  instead of the null data area used in the first embodiment or the second embodiment  there is used a transmitting method in which transmission using the repetition symbol data area is performed to enable an improvement in the reception quality even in the terminal device 600 that performs the MLD reception. However  the present invention is not limited to this configuration. A configuration and operation of a terminal device 600A that is a modified example of the terminal device 600 according to the third embodiment will be described below. In the terminal device 600A  processing to be described later is added to the normal MLD receiving process so that the null data area used in the first embodiment or the second embodiment can be applied as it is. [0204] A difference of the terminal device 600A from the terminal device 600 according to the third embodiment illustrated in FIG. 16 resides in that the MIMO receiving processor 609 is replaced with a MIMO receiving processor 609A. The other configurations are common to those of the terminal device 600  and therefore their detailed description will be omitted. [0205] A description will be given of a configuration of the MIMO receiving processor 609A of the terminal device 600A with reference to FIG. 18. FIG. 18 is a block diagram illustrating the configuration of the MIMO receiving processor 609A. The MIMO receiving processor 609 illustrated in FIG. 18 includes an LRU basis symbol data converter 631  an MLD processor 682  a pilot symbol data part power measurer 686  a data area part received power measurer 687  a received power comparator 688  and a null data symbol area decider 689. [0206] The pilot symbol data part power measurer 636 for each antenna
measures an average received power of the data signal per each antenna on the LRU basis  and outputs the measurement result to the received power comparator 638. [0207] The data area part received power measurer 637 for each antenna estimates an average received power per each antenna of the assumed pilot symbol from the channel estimate value on the LRU basis  and outputs the estimation result to the received power comparator 638. [0208] The received power comparator 638 compares an output of the pilot symbol data part power measurer 636 for each antenna with an output of the data area part received power measurer 637 for each antenna on the LRU basis  and outputs the comparison result to the null data symbol area decider
639. [0209] When a difference of the received power is a given value or more on the LRU basis  the null data symbol area decider 639 decides that the area is the null data area from the comparison result of the received power comparator 638  and outputs the decision result to the MLD processor 632. [0210] The MLD processor 632 performs the MLD processing on the basis of the output result of the null data symbol area decider 639 on the LRU basis. That is  when the determination result of the null data symbol area decider 639 is not the null data area in the subject LRU  the MLD processor 632 performs the normal MLD processing. On the other hand  when the determination result ofthe null data symbol area decider 639 is the null data area in the LRU  the MLD processor 632 does not generate the replica of the data symbol of the spatial stream addressed to another station except for the stream addressed to the own terminal device  and sets the null data area as the null data. Then  the MLD processor 632 generates the symbol replica of the other spatial stream  and performs the MLD processing  [0211] As described above  the terminal device 600A that is a modified example of the terminal device 600 according to the third embodiment adds the above-mentioned MLD processing to the normal MLD receiving process so as to apply the null data area used in the first embodiment or the second embodiment as it is. [0212] [First Modified example of Base Station Device 500] .
In this example  in the base station device 500 according to the third embodiment  instead of the null data area used in the first embodiment or the second embodiment  there is used a transmitting method in which transmission using the repetition symbol data area is performed to enable an improvement in the reception quality even in the terminal device 600 that performs the MLD reception  However  the present invention is not limited to this configuration  As a modified example of the base station device 500  a base station device 500A notifies the individual control information to be transmitted to each terminal device of the information on the null data area in another spatial stream in the individual control signal generator 133 so as to apply the null data area used in the first embodiment or the second embodiment as it is  [0213] [Second Modified example of Base Station Device 500]
In this example  in the repetition symbol data area signal generator 503 of the base station device 500 according to the third embodiment  the known symbol data is generated and transmitted  However  the present invention is not limited to this configuration  For example  as a second modified example of the base station device 500  a base station device 500B may use the individual data of the terminal device using the repetition symbol data area instead of the known symbol data  The base station device 500B will be described below  [0214] In this example  a difference of the base station device 500B from the base station device 500 of the third embodiment resides in that the repetition symbol data area signal generator 503 is replaced with a repetition symbol data area signal generator 503B  Only the configuration and operation thereof will be described  and the detailed description of the common configurations will be omitted  [0215] The repetition symbol data area signal generator 503B generates a signal of the repetition symbol data area with the use of partial data of the terminal device MS#n on the basis ofthe information on the null data area RA_NULL#n for the terminal device MS#n (n=l to S in this example)  [0216] That is  the repetition symbol data area signal generator 503B generates the signal of the repetition symbol data with the use of the symbol data included in the last LRU addressed to the terminal device MS#n using the same modulation system as that of the additional data area on the LRU basis as the symbol data of the LRU included in the null data area RA_NULL#n of the spatial stream #n addressed to the terminal device MS#n  Also  the repetition symbol data area signal generator 503B generates the normal pilot signal as the individual pilot symbol included in the repetition
..
symbol data area. [0217] [Second Modified Example of Terminal Device 600]
When the base station device 500B that is a second modified example of the base station device 500 according to the third embodiment is used as the base station device  the operation of the MIMO receiving processor 609 of the terminal device 600 illustrated in FIG. 16 is different. For that reason  a description will be given of the configuration and operation of an MIMO receiving processor 609B in a terminal device 600B as the second modified example of the terminal device 600. A difference of the terminal device 600B from the terminal device 600 illustrated in FIG. 16 resides in that the MIMO receiving processor 609 is replaced with the MIMO receiving processor 609B  and the detailed""description of the other common configurations will be omitted. [0218] The terminal device 600B can improve the MLD reception quality during the MLD receiving process in the repetition symbol data area using the individual data ofthe terminal device. [0219] A description will be given of a configuration of the MIMO receiving processor 609B in the terminal device 600B with reference to FIG. 19. FIG. 19 is a block diagram illustrating the configuration of the MIMO receiving processor 609B in the terminal device 600B. The MIMO receiving processor 609B illustrated in FIG. 19 includes an LRU basis symbol data converter 641  an MLD processor 642  an LRU basis hard decision value memory 643  a repetition symbol area matching""detector 644  a likelihood value updater 645  and a repetition symbol area decider 646. [0220] The LRU basis symbol data converter 641 permutates data of the PRU basis into data of the LRU basis on the basis of the output data of the receivers 203 for each of the reception antennas 201  and outputs the data of the LRU basis to the MLD processor 642. [0221] The MLD processor 642 performs the MLD processing on the basis of the channel matrix H that is the output from the channel estimator 207  the pilot sequence information PSI for the spatial stream addressed to the own terminal device or another terminal device  which is an output from the control information extractor 205  and the modulation information included in the MCS information. The MLD receiving process may use  for example  a technique disclosed in Non""patent Literature 4. Then  the MLD processor 642 outputs a soft decision value of the LRU basis of all the spatial streams
to be subjected to the multiuser transmission to the decoder 211  the LRU basis hard decision value memory 643  and the repetition symbol area matching-detector 644. [0222] The LRU basis hard decision value memory 643 converts the output of the soft decision value from the MLD processor 642 into the hard decision value  and temporarily stores the result. [0223] The repetition symbol area matching-detector 644 converts the output of the soft decision value from the MLD processor 642 into the hard decision value for the subsequent LRU  and detects a consistency of the converted hard decision value and the hard decision value stored in the LRU basis hard decision value memory 643  which has a time delay on the LRU basis. Then  when the consistency is a given value or more  the repetition symbol area matching-detector 644 outputs the converted hard decision value as the soft decision value ofthe repetition symbol area to the likelihood value updater 645. [0224] The likelihood value updater 645 updates the likelihood value of the spatial stream transmitted by plural times with the use of the repetition"" symbol area  and decides the symbol on the basis of the updated likelihood value. [0225] When the repletion symbol area is included in the part (Yk) of the spatial streams (Yl  Y2  ".  YS)  the MLD processor 642 generates a replica in which the symbol ofYk is decided at the time of generating the replica in the MLD processor 622 on the basis of the symbol decision result from the likelihood value up dater  and performs the MLD processing for estimating the symbol of the remaining undecided spatial streams with the use of the maximum likelihood estimation standard.
[0226] As described above  the terminal device 600B that is the second modified example of the terminal device 600 according to the third embodiment can improve the MLD reception characteristic by reducing the number ofreception candidates through the above-mentioned MLD receiving process. [0227] [Third Modified Example of Base Station Device 500]
In this example  the repetition symbol data area signal generator 503 of the base station device 500 according to the third embodiment transmits the known symbol or the repetition symbol using a part of the user data to the repetition symbol area as described above. Then  the unit of the
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repetition symbol is set to the LRU basis  but the present invention is not limited to this configuration. For example  the unit of the repetition symbol may be set to a value smaller than the LRU unit. [0228] In this example  the unit of the repetition symbol may be set to liN
(N: natural number) of the LRU. In this case  even if the size of the repetition symbol area is 1 LRU  because the repetition symbol is transmitted by plural times (N times per LRU)  the characteristic improvement is enabled in the repetition symbol area by the MLD receiving process based on the detection result together with the detection within 1 LRU. However  when N is too large  a length of the symbol that performs repetition becomes small  as a result of which when the symbol is not an original repetition symbol  there is a possibility that consistency erroneously occurs. That is  because there is a trade-off between the area detection precision and the reception characteristic improvement  there is a need to increase N to some degree. Taking this into account  N=3  4  or 8 is effective. This is because the MLD reception that improves the reception quality can be applied to an area of half the LRU or more  and there are two or more timings of the match detection within one LRU. [0229] FIG. 20 schematically illustrates a case of setting a repetitive symbol period with liN of the LRU as a unit in the two-user MU-MIN mode. The axis of ordinate in FIG. 20 represents an index of the spatial streams  and the axis of abscissa in FIG. 20 represents a resource index of the LRU basis. Also  blocks hatched in the figure represent the additional data area. Also  it is assumed that the terminal device MS#l is the MLD reception compliant terminal device. As illustrated in FIG. 20  the repetition symbol area partitioned by the liN unit of the LRU is disposed on the back of the additional data area of the spatial stream #2  thereby enabling the characteristic improvement in the repetition symbol area. [0230] In the description of the above respective embodiments  the antennas are applied. An antenna port is similarly applicable. The antenna port means a logical antenna configured by one or plural physical antennas. That is  the antenna port does not always mean one physical antenna  but may mean an array antenna configured by plural antennas. For example  in an LTE  the antenna port is not specified by the number of physical antennas configuring the antenna port  but specified as a minimum unit for allowing the base station to transmit different reference signals. Also  the
antenna port may be specified as a minimum unit for multiplying a pecoding vector. [0231] Also  the respective functional blocks used in the description of the above respective embodiments are typically realized as an LSI that is an integrated circuit. Each of those functional blocks may be integrated into one chip  or parts or all of those functional blocks may be integrated into one chip. The LSI in this example may be called an Ie  a system LSI  a super LSI  or an ultra LSI depending on a difference of integration. [0232] Also  a technique of the integrated circuit is not limited to the LSI  but may be realized by a dedicated circuit or a general-purpose processor There may be used an FPGA (field programmable gate array) that is programmable after manufacturing an LSI  or a reconfigl.uable processor that can reconfigure the connection or setting of a circuit cell within the LSI. [0233] Further  if a technology for integration circuit which is substituted for the LSI appears due to the development of the semiconductor technology or another technology derived therefrom  the functional blocks may be integrated by that technology. A biotechnology may be applied. [0234] The present invention has been described in detail and with reference to the specified embodiments. However  it would be apparent to one skilled in the art that the present invention could be variously modified or corrected without departing from the spirit and scope of the present invention.
[0235] The present invention is based on Japanese Patent Application No. 2009-173369 filed on July 24  2009  and content thereof is incorporated herein by reference.
Industrial Applicability [0236] The wireless communication device and the wireless communication method according to the present invention has such an advantage that a bias ofthe reception quality between the spatial streams can be suppressed  and is useful as the wireless communication device.
Reference Signs List [0237] 100  100A  300  500: base station device
101: antenna 103 : receiver
106: feedback information extractor
107: terminal device allocator
109: resource allocation information extractor Ill  111A: additional data area setting section
113: null data area setting section
115: pilot sequence allocator 120  120A: individual control signal and individual data signal generator
121: additional data generator
122: mode information/stream number information generator
123: resource allocation information generator
124: individual ID information generator
125: pilot sequence information generator
126: null data area signal generator
131: MCS information generator
133: individual control signal generator
135: encoder/modulator
137: individual pilot adder
139: precoding controller
141: beam-forming section
143: spatial stream power controller
151: OFDMA frame-forming section
153: IFFT section
155: transmitter 200  600: terminal device
201: reception antenna
203: receiver
205: control information extractor 20T channel estimator 209  609  609A  609B: MIMO receiving processor
211: decoder
213: precoding weight selector and reception quality estimator
215: feedback information generator 21T transmitter
219: transmission antenna
301: resource allocation method detector
302: pilot transmission controller
o•~•
~
320: individual control signal and individual data signal generator
326: null data area signal generator
501: resource allocation method detector
502: data transmission controller
503: repetition symbol data area signal generator
520: individual control signal and individual data signal generator 621 631  641:LRU basis symbol data converter 622  632  642: MLD processor
623: repetition symbol area matching-detector
624: known symbol memory
625: repetition symbol area decider
636: pilot symbol data part power measurer
637: data area part received power measurer
638: received power comparator
639: null data symbol area decider
643: LRU basis hard decision value memory
644: repetition symbol area matching-detector
645: likelihood value updater
646: repetition symbol area decider
-. 
Amendment under peT Article 19(1)
CLAlMS
Claim 1 {Amended} A wireless communication device for performing a spatial multiplexing transmission with respect to a plurality of terminal devices  the wireless communication device comprising:
a signal generator that is configured to allocate a pilot sig""nal to a part of at least one or more resource allocation areas to which no data addressed to the terminal device is allocated among resource allocation areas for the spatial multiplexing transmission based on a resource allocation method for allocating data addressed to the plurality of terminal devices; and
a transmitter that is configured to transmit the data addressed to the plurality of terminal devices and the pilot signal.
Claim 2 {Amended} The wireless communication device according to claim 1  wherein
the signal generator allocates the pilot signal for which a transmission power is set to 0 or the pilot signal for which a transmission power is set to a predetermined value other than 0 based on the resource allocation method for allocating data addressed to the plurality of terminal devices.
Claim 3 {Amended} The wireless communication device according to claim 1 or 2  wherein
the signal generator sets the transmission power of the pilot signal to 0 when the resource allocation method for allocating data addressed to the plurality of terminal devices is a continuous mapping.
Claim 4 {Amended} The wireless communication device according to claim
1 or 2  wherein
the signal generator sets the transmission power of the pilot signal to the predetermined value other than 0 when the resource allocation method for allocating data addressed to the plurality of terminal devices is a distributed mapping.
Claim 5 {Amended} The wireless communication device according to claim 1  wherein
Amendment under peT Article 19(1)
the part of at least one or more resource allocation areas to which no data addressed to the terminal device is allocated is an area on a subband basis being configured by a plurality of physical resource units and continuously provided in a frequency domain.
Claim 6 (Amended) The wireless communication device according to claim 1  further comprising:
an additional data generator that is configured to allocate additional data to at least one or more resource allocation areas to which no date addressed to the terminal device is allocated among resource allocation areas for the spatial multiplexing transmission which are allocated to each terminal device of the plurality of terminal devices  wherein
the transmitter transmits the data addressed to the plurality of terminal devices  the additional data and the pilot signal.
Claim 7 (Amended) The wireless communication device according to claim 6  wherein the additional data generator allocates repetition bit data or additional parity bit data as the additional data.
Claim 8 (Amended) The wireless communication device according to claim 6  further comprising:
a repetition symbol data generator that is configured to allocate known repetition symbol data to be transmitted to the plurality of terminal devices to an area which is at least one or more resource allocation areas to which no data addressed to the terminal device is allocated among the resource allocation areas for the spatial multiplexing transmission and is not allocated to the additional data area  wherein
the transmitter transmits the data addressed to the plurality of terminal devices  the additional data  the pilot signal and the repetition symbol data.
Claim 9 (Amended) A wireless communication method for performing a
spatial multiplexing transmission with respect to a plurality of terminal
devices  the wireless communication method comprising:
allocating a pilot signal to a part of at least one or more resource
;---""--¬
--. 
Amendment under peT Article 19(1)
allocation areas to which no data addressed to the terminal device is allocated among resource allocation areas for the spatial multiplexing transmission based on a resource allocation method for allocating data addressed to the plurality of terminal devices; and
transmitting the data addressed to the plurality of terminal devices and the pilot signal.