JP5859786B2 - Wireless transmission device, wireless reception device, wireless communication system, program, and integrated circuit - Google Patents

Description

  The present invention relates to a technique for simultaneously transmitting data from a wireless transmission device to a plurality of wireless reception devices using spatial multiplexing.

  MIMO (Multiple-Input Multiple-Output) transmission technology that uses multiple antennas for transmission and reception, spatially multiplexes multiple different data sequences (data streams) in the same frequency band and communicates simultaneously, It has been put to practical use in wireless LANs and cellular systems. In a next-generation cellular system, wireless LAN, or the like, a system has been proposed in which the number of transmission antennas included in a wireless transmission device is significantly larger than the number of reception antennas included in a wireless reception device. In such a system, a multi-user MIMO (Multi-User MIMO) that multiplexes data sequences addressed to a plurality of radio receiving apparatuses (users) in order to further improve the system throughput by effectively using the transmitting antenna of the radio transmitting apparatus. MIMO) has been proposed.

  However, since signals received by other wireless receiving devices cannot be known among a plurality of wireless receiving devices that receive signals multiplexed in multi-user MIMO, between users occurring between streams directed to each user as they are Interference (Multi-User Interference: MUI) significantly degrades the characteristics. Here, if the wireless transmission device recognizes CSI (Channel State Information) that is channel state information from each transmission antenna of the wireless transmission device to each reception antenna of each wireless reception device, a large load is imposed on the wireless reception device. Several methods have been proposed that can generate a transmission signal that can suppress MUI at the time of reception in a wireless reception device without being applied (Non-Patent Document 1).

For example, there is a method of performing transmission after precoding a transmission signal in a wireless transmission device so that reception can be performed in a state where MUI is suppressed at the time of reception in the wireless reception device. As an example, from the channel matrix H having the complex propagation path gain between each transmission antenna and each reception antenna of each wireless reception device obtained from CSI as its element, its inverse matrix H ⁻¹ (or pseudo inverse matrix H ^† = H ^H (HH ^H ) ⁻¹ : The superscript H represents Hermitian conjugate) is used as a weighting matrix (linear filter) W to weight the transmission signal (multiply the transmission signal by W = H ⁻¹ ). Weight matrix (linear filter) W = H ^H (HH ^H + αI) ⁻¹ (I is a unit matrix, α) obtained by Zero-forcing (ZF) precoding or Minimum Mean Square Error (MMSE) norm There is linear precoding (LP) that precodes a transmission signal by linear processing, such as MMSE precoding that weights the transmission signal with a normalization coefficient.

As another example, a signal point where transmission power is reduced in the signal space in order to suppress transmission power that is increased after interference subtraction is performed by subtracting the interference signal component obtained from CSI in advance. There is non-linear precoding (NLP) in which a transmission signal is precoded by non-linear processing for encoding a signal after interference subtraction. As one of the nonlinear precoding, Tomlinson-Harashima, which can suppress an increase in transmission power by performing a modulo operation on a signal in both a radio transmission apparatus and a radio reception apparatus. Precoding (Tomlinson-Harashima Precoding: THP) has been proposed (Non-Patent Document 2, Non-Patent Document 3, Non-Patent Document 4). At this time, the radio receiving apparatus on the receiving side also performs the modulo operation similar to the transmission on the received signal. Here modulo operation Mod _tau modulo width tau, when a complex vector representing the received signal in the signal or receiver after interference subtraction on the transmission side [nu, represented by the formula (1). J is an imaginary unit, floor (a) is the maximum integer not exceeding a, and Re (ν) and Im (ν) are the real part of the complex number ν (corresponding to the in-phase component of the signal) and the imaginary part ( Corresponding to the orthogonal component of the signal). The non-linear processing here mainly means processing using processing in which discontinuities exist in output such as modulo arithmetic.

  Furthermore, considering the characteristic degradation called Modulo-Loss at low signal-to-noise power ratio (SNR) caused by modulo arithmetic in THP, the MUI is small and the transmission power suppression effect by modulo arithmetic is small. A method for performing non-linear precoding by THP by applying modulo arithmetic only to a terminal having a large MUI and a large transmission power suppression effect by modulo arithmetic, by performing the same processing as linear precoding without applying modulo arithmetic for the terminal Has been proposed (Non-Patent Document 6).

  On the other hand, as a method for identifying a plurality of radio reception devices that are destinations of a data sequence spatially multiplexed on a multiuser MIMO signal transmitted from a radio transmission device, a combination (group) of radio reception devices spatially multiplexed by multiuser MIMO The method of embedding a group ID (Group ID: GID) for identifying each group in the control information of the transmission frame at the time of multi-user MIMO transmission is the IEEE (The Institute of Electrical and Electronics) Engineers, Inc.) 801.11ac (Non-Patent Document 7). Here, each wireless reception device can belong to a plurality of groups. Note that the above combinations are groups in which a wireless transmission device (access point) determines a combination (group) of wireless reception devices spatially multiplexed by multiuser MIMO and identifies each group prior to multiuser MIMO transmission. An ID is added to notify each wireless reception device to which group it belongs. The group configuration is notified to the wireless reception device by the wireless transmission device.

Spencer et al., "An Introduction to the Multi-User MIMO Downlink", IEEE Communication Magazine, Vol. 42, Issue 10, p. 60-67, October 2004 Harashima et al., "Matched-Transmission Technique for Channels With Intersymbol Interference", IEEE Transaction on Communications, Vol.COM-20, No.4, p.774-780, August 1972 J. Liu et al., “Improved Tomlinson-Harashima Precoding for the Downlink of Multiple Antenna Multi-User Systems”, Proc. IEEE Wireless and Communications and Networking Conference, p.466-472, March 2005. M. Joham et al., “MMSE Approaches to Multiuser Spatio-Temporal Tomlinson-Harashima Precoding”, Proc. 5th Int. ITG Conf. On Source and Channel Coding, p.387-394, January 2004 P.W.Wolniansky et al., `` V-BLAST: an architecture for realizing very high data rates over the rich-scattering wireless channel '', Proc.ISSSE-98, p.295-300, September 1998 Nakano et al., “Proposal for Downlink MU-MIMO THP to Adaptively Control Transmission Methods”, IEICE Technical Report, RCS2009-293, March 2010 `` IEEE P802.11 Wireless LANs Specification Framework for TGac '', IEEE 802.11-09 / 0992r21, January 2011 Kazuki Takeda et al., “Single-Carrier HARQ Using Joint THP and FDE”, Proc. 2007 IEEE 66th Vehicular Technology Conference (VTC-2007 Fall), p.1188-1192, September 2007

  Unlike a case of linear precoding, a radio reception apparatus that receives a signal that has been subjected to interference suppression by nonlinear precoding needs to perform the same modulo operation on the received signal as the transmission side. For this reason, in a wireless communication system, when a wireless transmission device supports both linear precoding and nonlinear precoding and a wireless reception device supports both linear precoding and nonlinear precoding, it is further non-patented. When two types of interference suppression methods are used in combination, such as when the wireless transmission device performs interference suppression by simultaneously combining linear precoding and nonlinear precoding as in Document 6, the wireless reception device It is necessary to switch whether to perform modulo calculation according to the interference suppression method. For this reason, the radio transmission apparatus controls whether a signal received by the radio reception apparatus is linear precoding or non-linear precoding with respect to a reception apparatus that receives a signal transmitted with interference suppressed. There is a problem that the amount of control information increases because it is necessary to notify the information.

  The present invention has been made in view of such circumstances, and does not increase the amount of control information whether the multiuser MIMO signal transmitted from the wireless transmission device is linear precoding or non-linear precoding. An object of the present invention is to provide a wireless transmission device, a wireless reception device, a wireless communication system, a program, and an integrated circuit that can notify the wireless reception device.

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the wireless transmission device of the present invention is a wireless transmission device that includes a plurality of transmission antennas and transmits spatially multiplexed signals to a plurality of wireless reception devices, and each receives a plurality of wireless receptions from the plurality of wireless reception devices. Select a device to create a plurality of groups, determine a precoding method for performing precoding on signals to be transmitted to radio reception devices belonging to each group, and support the precoding method A group configuration unit that assigns one identification number to each group from among predetermined identification number candidates, a selection unit that selects any one group from the groups, and the selected A precoding corresponding to an identification number assigned to the selected group for a signal transmitted to a wireless reception device belonging to the group. Characterized in that it comprises a precoding section in loading scheme performs precoding, the.

  As described above, since a signal to be transmitted to a radio reception apparatus belonging to the selected group is precoded by a precoding scheme corresponding to the identification number assigned to the selected group, the radio reception apparatus It is possible to identify from the identification number whether the multiuser MIMO signal transmitted from the transmission apparatus has been precoded by the linear precoding scheme or by the non-linear precoding scheme. Thereby, it is possible to notify the radio reception apparatus of the precoding scheme without increasing the amount of control information.

  (2) Moreover, the wireless transmission device of the present invention includes a group storage unit that stores the created group, a configuration information generation unit that generates group configuration information for each group, and an identification number of the selected group An identification information generation unit that generates group identification information that notifies the group configuration information, transmitting the group configuration information to each of the wireless reception devices, and transmitting the group identification information and the precoded signal to the selected group. It transmits to each wireless receiver which belongs.

  With this configuration, it is possible to notify the wireless receiver of the precoding scheme without increasing the amount of control information.

  (3) Further, in the wireless transmission device of the present invention, the precoding scheme is one of linear precoding and nonlinear precoding.

  With this configuration, both linear precoding and non-linear precoding can be handled, and both can be switched and used.

  (4) In the wireless transmission device of the present invention, the precoding method is any one of linear precoding, nonlinear precoding, or linear nonlinear mixed precoding in which linear precoding and nonlinear precoding are mixed. It is characterized by.

  With this configuration, it is possible to notify the wireless receiver of the precoding scheme without increasing the amount of control information.

  (5) Moreover, in the wireless transmission device of the present invention, the precoding unit is configured to select the selected group when the precoding scheme corresponding to the identification number assigned to the selected group is nonlinear precoding. A modulo operation is performed on a signal transmitted to a wireless receiver belonging to the above.

  With this configuration, since the precoding scheme can be identified by the identification number, it is possible to notify the radio receiving apparatus of the precoding scheme without increasing the amount of control information.

  (6) Moreover, in the wireless transmission device of the present invention, the precoding unit includes a noncoding precoding method corresponding to an identification number assigned to the selected group, and the selected group includes In the case where a radio receiving apparatus corresponding only to linear precoding belongs, a modulo operation is not performed on a signal transmitted to the radio receiving apparatus corresponding only to the linear precoding.

  With this configuration, it is possible to receive a linear precoded multi-user MIMO signal from a wireless transmission device, even if the wireless reception device does not support a non-linear precoding scheme, without adding special processing. It becomes.

  (7) In the wireless transmission device of the present invention, the group configuration unit further determines the order of each wireless reception device belonging to each group in the group, and the precoding unit determines the selected group When the precoding scheme corresponding to the assigned identification number is linear / non-linear mixed precoding, a signal to be transmitted to a wireless reception device in an order before a predetermined threshold among wireless reception devices belonging to the selected group. In this case, the modulo operation is not performed, and the modulo operation is performed on the signal transmitted to the wireless reception device in the order after the threshold value.

  With this configuration, it is possible to notify the wireless receiver of the precoding scheme without increasing the amount of control information.

  (8) Moreover, in the wireless transmission device of the present invention, the precoding unit is configured so that a precoding scheme corresponding to an identification number assigned to the selected group is linear nonlinear mixed precoding, and the selected In the case of a radio receiving device corresponding to only linear precoding included in a radio receiving device in an order after the threshold among radio receiving devices belonging to a group, a signal to be transmitted to a radio receiving device corresponding only to the linear precoding On the other hand, the modulo operation is not performed.

  With this configuration, it is possible to notify the wireless receiver of the precoding scheme without increasing the amount of control information.

  (9) In the wireless transmission device of the present invention, the group configuration unit allows a wireless reception device that supports only linear precoding to be included in the same group as a wireless reception device that supports nonlinear precoding. It is characterized by.

  With this configuration, since the precoding scheme can be identified by the identification number, it is possible to notify the radio receiving apparatus of the precoding scheme without increasing the amount of control information.

  (10) According to another aspect of the present invention, there is provided a wireless reception device that receives a spatially multiplexed signal from a wireless transmission device having a plurality of transmission antennas, wherein a group identification number is received from the wireless transmission device. An identification information acquisition unit that acquires group identification information to be notified; a determination unit that determines whether or not the own device belongs to the group indicated by the identification number; and as a result of the determination, if the own device belongs to the group, A reception processing unit that performs a reception process according to a precoding scheme determined in advance corresponding to the identification number.

  As described above, when the own apparatus belongs to the group, reception processing is performed according to a precoding scheme determined in advance corresponding to the identification number, so that the multiuser MIMO signal transmitted from the radio transmission apparatus is linear. It is possible to identify from the identification number whether the precoding has been performed by the precoding scheme or the non-linear precoding scheme. Thereby, it is possible to notify the radio reception apparatus of the precoding scheme without increasing the amount of control information.

  (11) In addition, the wireless reception device of the present invention includes a configuration information acquisition unit that acquires group configuration information of a group to which a wireless reception device that is a transmission destination of the wireless transmission device belongs, and a group storage that stores the group information And a section.

  With this configuration, it is possible to receive a notification of a precoding scheme without increasing the amount of control information.

  (12) In the wireless reception device of the present invention, the precoding scheme is either linear precoding or non-linear precoding, and the reception processing unit is configured such that the precoding scheme is non-linear precoding. Is characterized by performing a modulo operation on the received data symbols.

  With this configuration, since the precoding scheme can be identified by the identification number, it is possible to receive notification of the precoding scheme without increasing the amount of control information.

  (13) Moreover, in the radio reception apparatus of the present invention, the precoding scheme is any one of linear precoding, nonlinear precoding, or linear nonlinear mixed precoding in which linear precoding and nonlinear precoding are mixed, The reception processing unit performs a modulo operation on a received data symbol when the precoding scheme is nonlinear precoding.

  With this configuration, since the precoding scheme can be identified by the identification number, it is possible to receive notification of the precoding scheme without increasing the amount of control information.

  (14) In the wireless reception device of the present invention, the precoding method is any one of linear precoding, nonlinear precoding, or linear nonlinear mixed precoding in which linear precoding and nonlinear precoding are mixed, The reception processing unit performs a modulo operation on a received data symbol when the precoding scheme is linear nonlinear mixed precoding and the order of the own device in the group is after a predetermined threshold. Features.

  With this configuration, since the precoding scheme can be identified by the identification number, it is possible to receive notification of the precoding scheme without increasing the amount of control information.

  (15) A wireless communication system according to the present invention includes a wireless transmission device according to any one of (1) to (9), and a wireless reception device according to any one of (10) to (14). It is characterized by comprising.

  With this configuration, it is possible to notify the wireless receiver of the precoding scheme without increasing the amount of control information.

  (16) A program of the present invention is a program for a wireless transmission device that includes a plurality of transmission antennas and transmits a spatially multiplexed signal to a plurality of wireless reception devices. A process of selecting a plurality of groups by selecting a radio reception apparatus, and a process of determining, for each group, a precoding scheme for precoding signals transmitted to radio reception apparatuses belonging to each group , A process of assigning one identification number to each group from among identification number candidates predetermined corresponding to the precoding scheme, a process of selecting any one group from the groups, An identification number assigned to the selected group with respect to a signal to be transmitted to the wireless reception devices belonging to the selected group Response and processing for performing precoding in a precoding scheme that, the series of processes to be characterized by causing a computer to execute.

  As described above, since a signal to be transmitted to a radio reception apparatus belonging to the selected group is precoded by a precoding scheme corresponding to the identification number assigned to the selected group, the radio reception apparatus It is possible to identify from the identification number whether the multiuser MIMO signal transmitted from the transmission apparatus has been precoded by the linear precoding scheme or by the non-linear precoding scheme. Thereby, it is possible to notify the radio reception apparatus of the precoding scheme without increasing the amount of control information.

  (17) A program according to the present invention is a program for a radio reception apparatus that receives a spatially multiplexed signal from a radio transmission apparatus having a plurality of transmission antennas, and the group identification number is received from the radio transmission apparatus. A process of acquiring group identification information to be notified; a process of determining whether or not the own apparatus belongs to the group indicated by the identification number; and if the result of the determination is that the own apparatus belongs to the group, Correspondingly, the computer is caused to execute a series of processes including a process for receiving a signal addressed to the own apparatus in accordance with a precoding method determined in advance.

  Thus, when the own device belongs to the group, reception processing is performed according to a precoding scheme determined in advance corresponding to the identification number, so that the multi-user MIMO signal transmitted from the wireless transmission device is It is possible to identify from the identification number whether the precoding is performed by the linear precoding method or the non-linear precoding method. Thereby, it is possible to notify the radio reception apparatus of the precoding scheme without increasing the amount of control information.

  (18) An integrated circuit according to the present invention is an integrated circuit that is mounted on a wireless transmission device having a plurality of transmission antennas to cause the wireless transmission device to perform a plurality of functions. A function of transmitting a spatially multiplexed signal to a device, a function of selecting a plurality of wireless receiving devices from a plurality of wireless receiving devices, and creating a plurality of groups, and transmitting to a wireless receiving device belonging to each group A function for deciding a precoding scheme for precoding for a signal for each group, and one identification number from among candidates for identification numbers predetermined corresponding to the precoding scheme, A function to be assigned to the group, a function to select any one group from the groups, and a wireless reception device belonging to the selected group A function of performing precoding with a precoding scheme corresponding to an identification number assigned to the selected group with respect to a signal to be transmitted to the wireless transmission device. To do.

  As described above, since a signal to be transmitted to a radio reception apparatus belonging to the selected group is precoded by a precoding scheme corresponding to the identification number assigned to the selected group, the radio reception apparatus It is possible to identify from the identification number whether the multiuser MIMO signal transmitted from the transmission apparatus has been precoded by the linear precoding scheme or by the non-linear precoding scheme. Thereby, it is possible to notify the radio reception apparatus of the precoding scheme without increasing the amount of control information.

  (19) Further, an integrated circuit according to the present invention is an integrated circuit that is mounted on a wireless receiving device, thereby causing the wireless receiving device to perform a plurality of functions, and includes a plurality of transmitting antennas. A function of receiving a spatially multiplexed signal, a function of acquiring group identification information for notifying a group identification number from the wireless transmission device, and determining whether the own device belongs to the group indicated by the identification number A function and a function of receiving a signal addressed to the own device according to a precoding scheme determined in advance corresponding to the identification number when the own device belongs to the group as a result of the determination. The function is exhibited by the wireless receiver.

  Thus, when the own device belongs to the group, reception processing is performed according to a precoding scheme determined in advance corresponding to the identification number, so that the multi-user MIMO signal transmitted from the wireless transmission device is It is possible to identify from the identification number whether the precoding is performed by the linear precoding method or the non-linear precoding method. Thereby, it is possible to notify the radio reception apparatus of the precoding scheme without increasing the amount of control information.

  According to the present invention, it is possible to notify a radio reception apparatus whether the multiuser MIMO signal transmitted from the radio transmission apparatus is linear precoding or non-linear precoding without increasing the amount of control information. Become.

It is a figure which shows the schematic structural example of the communication system of this invention. It is a functional block diagram which shows one structural example of the radio | wireless transmitter 100 of this invention. It is a functional block diagram which shows the precoding part 323a which is one structural example of the precoding part 323 which concerns on the 1st Embodiment of this invention. It is a functional block diagram which shows the example of 1 structure of the linear precoding part 401 which concerns on the 1st Embodiment of this invention. It is a functional block diagram which shows the example of 1 structure of the nonlinear precoding part 403 which concerns on the 1st Embodiment of this invention. It is a functional block diagram which shows the radio | wireless receiver 200a which is one structural example of the radio | wireless receiver 200 which concerns on the 1st Embodiment of this invention. It is a functional block diagram which shows the radio | wireless receiver 200b which is another structural example of the radio | wireless receiver 200 which concerns on the 1st Embodiment of this invention. It is a functional block diagram which shows the radio | wireless receiver 200c which is another structural example of the radio | wireless receiver 200 which concerns on the 1st Embodiment of this invention. FIG. 3 is a diagram illustrating an example of group information created by the group configuration unit 307 of the wireless transmission device 100 and shared with the wireless reception device 200 in the first embodiment of the present invention. 2 shows an example of a sequence chart showing an operation between the wireless transmission device 100 and each wireless reception device according to the first embodiment of the present invention. 2 shows an example of a sequence chart showing an operation between the wireless transmission device 100 and each wireless reception device according to the first embodiment of the present invention. It is a functional block diagram which shows the precoding part 323b which is one structural example of the precoding part 323 which concerns on the 2nd Embodiment of this invention. It is a functional block diagram which shows the example of 1 structure of the mixed precoding part 801 which concerns on the 2nd Embodiment of this invention. In the 2nd Embodiment of this invention, it is a figure which shows an example of the group information produced in the group structure part 307 of the radio | wireless transmitter 100, and is shared with the radio | wireless receiver 200. FIG. FIG. 10 is a diagram illustrating an example of group information created by the group configuration unit 307 of the wireless transmission device 100 and shared with the wireless reception device 200 in the third embodiment of the present invention.

  Hereinafter, a communication technique according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
For the communication technology according to the present embodiment, a wireless transmission device (base station device, access point, etc.) selects a plurality of wireless reception devices from a plurality of wireless reception devices (terminal devices) and performs multi-user MIMO transmission. An example will be described of a wireless communication system in which inter-user interference (MUI) that occurs between streams addressed to each wireless reception apparatus is suppressed in advance by linear precoding or non-linear precoding.

  FIG. 1 is a diagram showing a schematic configuration example of a wireless communication system of the present invention. As illustrated in FIG. 1, in the wireless communication system according to the present embodiment, the wireless transmission device 100 includes a plurality of wireless reception devices (for example, wireless reception devices 200-1 to 200-8, wireless reception devices 200-1 to 200-8). Are also referred to as a wireless receiving device 200), the wireless transmitting device 100 creates a plurality of groups by a plurality of combinations of these wireless receiving devices 200, and sets a group identification number (group ID) for identifying the group. Give. One radio receiving apparatus 200 can belong to a plurality of groups. In this embodiment, a precoding scheme used for multi-user MIMO transmission is determined in advance by the system for each group ID. In other words, a plurality of group ID candidates corresponding to a precoding scheme used for multiuser MIMO transmission (specifically, for example, a plurality of candidates distinguished by a range of group ID values, a bit pattern, or the like). For each created group, a different one is selected from the group ID candidates corresponding to the precoding scheme used for each group, and given as a group ID for each group. When the group ID is represented by 6 bits (from 0 to 63), for example, the group up to 31 is a group using linear precoding (first group), and the group after 32 is a group using nonlinear precoding (second) ) And the like. Note that the group ID of the first group and the group ID of the second group may be distinguished by using a method of dividing the range of group IDs that can be taken as described above into two, or the group ID is a binary number. The method of dividing by the value of the specific bit expressed by (for example, the first group when the specific bit is 0, the second group when the specific bit is 1) may be used. In addition, any method may be used as long as it is determined in advance by the system and can distinguish which group belongs only from the group ID.

  The wireless transmission device 100 performs the above grouping information (information about which group each wireless reception device 200 belongs to) and the processing order of the associated wireless reception device in each group (propagation path information in multiuser MIMO transmission processing). Information defining the order of notification, ACK / NAK response, etc., the order of individual information addressed to each wireless reception device 200 in the control signal, the order of spatial streams, etc.) is notified to the wireless reception device 200 prior to communication. The wireless transmission device 100 selects one of the combinations of the wireless reception devices 200 (target wireless reception devices) to be subjected to multi-user MIMO transmission from the plurality of groups created above that are candidates for the combination. Multi-user MIMO transmission is performed in which transmission data addressed to a plurality of radio reception apparatuses 200 belonging to a group is spatially multiplexed in the same frequency band and simultaneously communicated. At this time, the wireless reception device 200 is notified of the group to be subjected to the multi-user MIMO transmission using a group ID for identifying the selected group. At the same time, the wireless reception device 200 can identify the precoding scheme used by the wireless transmission device 100 by the notification of the group ID. Further, although a radio communication system using orthogonal frequency division multiplexing (OFDM) as a transmission method will be described as an example, the present invention is not limited to this.

  Each of the wireless reception devices 200-1 to 200-8 receives a reference signal (a signal known in transmission / reception, such as a pilot signal and a training signal) from the wireless transmission device 100, and each of the transmission antennas of the wireless transmission device 100 and its own wireless A propagation path state between each reception antenna of the reception apparatus is estimated, and propagation path information representing the propagation path state is reported to the wireless transmission apparatus 100. Radio transmitting apparatus 100 selects one group from a plurality of groups based on propagation path information and the like reported from each radio receiving apparatus 200, and spatially multiplexes transmission data addressed to the plurality of radio receiving apparatuses 200. Multi-user MIMO transmission for simultaneous communication.

  For example, the propagation path information includes signal power to noise power ratio (SNR), signal power to interference plus noise power ratio (SINR), carrier power to noise power ratio (SINR) Carrier to noise power ratio (CNR), carrier power to interference plus noise power ratio (CINR), or reception quality information (Channel Quality Indicator: CQI) representing the value calculated from them, and radio Channel state information (Channel State Information: CSI) representing the complex channel gain from each transmitting antenna of transmitting apparatus 100 to each receiving antenna of each wireless receiving apparatus 200, its covariance value, etc., or a desired pre-determined from the channel state A coding matrix index (Precoding Matrix Index: PMI) or the like is received from each wireless reception device 200, and multi-user MIMO is based on the information. The group of the wireless receiving device 200 to be multiplexed is selected.

  FIG. 2 is a functional block diagram showing a configuration example of the wireless transmission device 100 of the present invention. A configuration example of the wireless transmission device 100 of FIG. 2 includes four antennas, and can transmit multi-user MIMO transmission by spatially multiplexing transmission data addressed to a maximum of four wireless reception devices 200. The wireless reception unit 301 receives signals transmitted from the wireless reception devices 200 (wireless reception devices 200-1 to 200-8) through a plurality of antennas of the antenna unit 303. The control information acquisition unit 305 is a precoding scheme that is received by the wireless reception device 200 that establishes communication for the first time, each wireless reception device 200 that is used when updating the grouping, and the like that is compatible with each wireless reception device 200. Information (corresponding information) or type information (terminal class, compliant standard information, receiving function information indicating presence / absence of modulo arithmetic function, etc.) that can identify the corresponding precoding scheme is acquired, and each wireless receiving device 200 is acquired. The corresponding precoding method information is output. In the present embodiment, as an example, in the communication system of FIG. 1, the radio reception devices 200-1, 200-2, 200-4, and 200-7 correspond to only linear precoding (not provided with a modulo arithmetic unit described later). ) Radio receiving apparatus 200 (hereinafter referred to as a linear radio receiving apparatus), and radio receiving apparatuses 200-3, 200-5, 200-6, and 200-8 correspond to both linear precoding and nonlinear precoding (modulo). Assume that the wireless receiving device 200 (hereinafter referred to as a non-linear wireless receiving device) includes an arithmetic unit. For example, the linear wireless reception device is a terminal device that supports multi-user MIMO using conventional linear precoding, and the nonlinear wireless reception device is a terminal device that supports multi-user MIMO using nonlinear precoding while maintaining backward compatibility. is there.

  The group configuration unit 307 creates a plurality of groups based on a plurality of combinations of the wireless reception devices 200 based on at least the corresponding precoding scheme information of the wireless reception devices 200 output from the control information acquisition unit 305, and each group The precoding scheme to be used is determined, and a group ID corresponding to the determined precoding scheme is assigned. For example, in the case of the above-described 6-bit group ID, the first group using linear precoding is assigned a group ID of up to 31 and the second group using non-linear precoding is assigned 32 or later. Assign a group ID. At this time, the order of each wireless reception device 200 in each group (the order of propagation path information notification, ACK / NAK response, etc. in multiuser MIMO transmission processing, the order of individual information addressed to each wireless reception device 200 in the control signal, space Stream order, etc.). One radio receiving apparatus 200 can belong to a plurality of groups. Further, there may be a wireless reception device 200 that does not belong to any group. However, a linear wireless reception apparatus that supports only linear precoding creates a group so as to belong only to the first group. Nonlinear radio reception apparatuses that support both linear precoding and nonlinear precoding can belong to both the first group and the second group. Further, grouping may be performed by further using information such as position information of each wireless reception device 200 and a result of estimating an arrival angle of a radio wave from each wireless reception device 200. In this case, for example, a group may be created between the wireless reception devices 200 that are separated from each other and the wireless reception devices 200 that are separated from each other in the radio wave arrival angle so that the correlation between the propagation paths becomes low. Further, there may be a plurality of groups in which the precoding scheme and the order of each wireless reception device 200 are different in the combination of the same wireless reception device 200. When a plurality of groups having different precoding schemes and orders are created by combining the same wireless reception devices 200 as described above, more efficient depending on the state of the propagation path of each of the combined wireless reception devices 200 It is possible to select a group defined with a good precoding scheme or order from the plurality of groups.

  The group storage unit 309 stores group information created by the group configuration unit 307 (group configuration information including the group ID, the wireless reception device 200 to which the group belongs, and the order of each wireless reception device 200 within the group). The configuration information generation unit 311 generates group configuration information for notifying each wireless reception device 200 of the group information created by the group configuration unit 307. Note that the group configuration information is notified to each wireless reception device 200 even if the wireless reception device 200 (identification information of the wireless reception device 200, that is, the user ID, MAC address, etc.) belonging to each group is notified. It is also possible to notify the group belonging to each wireless reception device 200 and the order information within the group. The propagation path information acquisition unit 313 acquires, from the received signal, propagation path information including CQI and CSI information transmitted by each of the wireless reception devices 200-1 to 200-8.

  The selection unit 315 is based on the transmission data amount and priority addressed to each wireless reception device 200 stored in the transmission buffer unit 317, the propagation path information of each wireless reception device 200 acquired by the propagation path information acquisition unit 313, and the like. Then, a group to which a plurality of radio reception devices 200 (target radio reception devices) multiplexed by multiuser MIMO belongs is selected from the plurality of groups stored in the group storage unit 309. Also, a precoding scheme selection signal indicating a precoding scheme determined in advance corresponding to the group ID of the selected group is output. Further, based on the CQI from each wireless reception device 200 acquired by the propagation path information acquisition unit 313, such as a modulation scheme and a coding rate (Modulation and Coding Scheme: MCS) for transmission data addressed to each wireless reception device 200 A parameter may be selected. In the present embodiment, a group to which the four terminals of the first to fourth radio receiving apparatuses 200 belong is selected from the radio receiving apparatuses 200-1 to 200-8, and one group (1) is assigned to each radio receiving apparatus 200. A case of transmitting a stream) will be described.

  The transmission buffer unit 317 accumulates transmission data sequences addressed to each wireless reception device 200 input from an upper layer, and stores the transmission data sequences addressed to the first to fourth wireless reception devices 200 selected by the selection unit 315. The data is output to the encoding unit 319. Encoding section 319 performs error correction encoding on the transmission data series addressed to first to fourth radio receiving apparatuses 200 input from transmission buffer section 317, respectively. In addition, when the coding rate of the transmission data addressed to each radio reception apparatus 200 is selected by selection unit 315, rate matching (puncturing) is performed according to the coding rate. When the coding rate is not specified, rate matching may be performed at a predetermined coding rate. Modulation section 321 modulates the transmission data series addressed to first to fourth radio reception apparatuses 200, each of which has been subjected to error correction coding, for each subcarrier addressed to first to fourth radio reception apparatuses 200, respectively. Output modulation symbols. Note that, when the selection unit 315 selects a modulation method for transmission data addressed to each wireless reception device 200, modulation is performed using the modulation method. When there is no designation of a modulation method, it is preferable to perform modulation by a predetermined modulation method.

  The precoding unit 323 receives each modulation symbol addressed to the first to fourth radio reception apparatuses 200 and inputs each modulation symbol based on the CSI from each radio reception apparatus 200 acquired by the propagation path information acquisition unit 313. The modulation symbol is precoded by a precoding scheme determined in accordance with the group ID of the group selected by the selection unit 315, and multi-user MIMO symbols for each of a plurality of antennas of the antenna unit 303 used for transmission are obtained. Generate. Details of the precoding unit 323 will be described later.

  Reference signal multiplexing section 325 multiplexes the reference signal transmitted from each antenna of antenna section 303 into the multiuser MIMO symbol transmitted from each antenna. Note that the reference signals are preferably multiplexed so that the reference signals transmitted from the respective antennas of the wireless transmission device 100 are received in the respective wireless reception devices 200 in an identifiable manner. Alternatively, it may be multiplexed by frequency division such as division by subcarriers, or may be multiplexed by code division. Also, for the purpose of causing each wireless reception device 200 to estimate the propagation path, when transmitting a sounding signal (sounding frame, sounding packet, null data packet) composed of a reference signal and a control signal that does not include a transmission data sequence The reference signal multiplexing unit 325 directly outputs a reference signal transmitted from each antenna.

  The IFFT unit 327 performs frequency time conversion such as Inverse Fast Fourier Transform (IFFT) on the multi-user MIMO signal for each antenna on which the reference signal is multiplexed, and converts the signal into a time domain signal. . The GI insertion unit 329 inserts a guard interval (GI) in the time domain signal for each antenna. Based on the selection result of the selection unit 315, the identification information generation unit 331 generates group identification information for notifying the wireless reception device 200 of a group identification number (group ID) for identifying the selected group. Further, it may include MCS information and the like for each wireless reception device 200. The wireless transmission unit 333 transmits the signal in which the GI is inserted through each antenna of the antenna unit 303. Further, the group configuration information generated by the configuration information generation unit 311 and the group identification information generated by the identification information generation unit 331 are transmitted through one or more antennas of the antenna unit 303. The control part 335 controls each said part, and performs each process.

  FIG. 3 is a functional block diagram showing a precoding unit 323a which is a configuration example of the precoding unit 323 according to the first embodiment of the present invention. The precoding unit 323a includes a linear precoding unit 401, a non-linear precoding unit 403, and a switching unit 405. The linear precoding unit 401 receives each modulation symbol addressed to the first to fourth radio reception apparatuses 200 and inputs each modulation symbol based on the CSI or PMI of the channel information acquired by the channel information acquisition unit 313. Linear precoding is performed on the modulation symbols. Details of the linear precoding unit 401 will be described later. The nonlinear precoding unit 403 receives each modulation symbol addressed to the first to fourth radio reception apparatuses 200 and inputs each modulation symbol based on the CSI or PMI of the channel information acquired by the channel information acquisition unit 313. Nonlinear precoding is performed on the modulation symbols. Details of the nonlinear precoding unit 403 will be described later.

  The switching unit 405 receives the linear precoding result output from the linear precoding unit 401 and the non-linear precoding result output from the non-linear precoding unit 403 and is based on the precoding scheme selection signal input from the selection unit 315. The first to fourth multiuser MIMO symbols to be transmitted from the respective antennas of the antenna unit 303 are output. In addition, it is preferable that the linear precoding unit 401 and the nonlinear precoding unit 403 do not perform the processing operation when the precoding scheme selection signal does not select the precoding scheme. As a result, power consumption can be reduced.

FIG. 4 is a functional block diagram showing a configuration example of the linear precoding unit 401 according to the first embodiment of the present invention. The linear precoding unit 401 includes a filter calculation unit 501 and a linear filter unit 503. In the example of FIG. 4, a case will be described in which a multiuser MIMO signal is generated by Zero-Forcing precoding based on CSI as linear precoding. The filter calculation unit 501 calculates the complex between each antenna of the wireless transmission device 100 and the antenna of each wireless reception device 200 from the CSI in the propagation channel information of each wireless reception device 200 acquired by the propagation channel information acquisition unit 313. A channel matrix H having a channel gain as an element is generated for each subcarrier, and its inverse matrix H ⁻¹ (or pseudo inverse matrix H ^† = H ^H (HH ^H ) ⁻¹ ) is used as a weighting matrix W that is a linear filter. calculate. The linear filter unit 503 receives the modulation symbols addressed to the first to fourth radio receiving apparatuses as inputs, multiplies the linear filter W calculated by the filter calculation unit 501 for each subcarrier, A multi-user MIMO symbol to be transmitted is output.

Thus, when each radio receiving apparatus 200 receives the multiuser MIMO symbol, interference (MUI) due to a signal other than the own radio receiving apparatus is canceled by linear precoding, and only the signal addressed to the own radio receiving apparatus is received. Is done. In the linear precoding unit 401, an example has been described in which the filter calculation unit 501 calculates and uses an inverse matrix as a linear filter. However, the present invention is not limited to this, and the weight matrix W = H ^H obtained by the MMSE norm is used. (HH ^H + αI) ⁻¹ (I represents a unit matrix, α represents a normalization coefficient) may be used as a linear filter. In this case, the MUI is not completely canceled at the time of reception, but the SINR can be maximized, so that reception characteristics are improved. In a communication system using PMI, the filter calculation unit 501 obtains a weight matrix from the precoding vector indicated by the PMI of each wireless reception device 200 and uses it as a linear filter.

FIG. 5 is a functional block diagram showing a configuration example of the nonlinear precoding unit 403 according to the first embodiment of the present invention. In the example of FIG. 5, a case will be described in which a multiuser MIMO signal is generated by Tomlinson-Harashima precoding (THP) as nonlinear precoding. The QR decomposition unit (interference matrix calculation unit) 601 determines each antenna of the wireless transmission device 100 and each wireless reception device 200 from the CSI in the propagation channel information of each wireless reception device 200 acquired by the propagation channel information acquisition unit 313. A channel matrix H having a complex channel gain with respect to the antenna as an element is generated for each subcarrier, and Hermitian conjugate H ^H of the channel matrix H is subjected to QR decomposition to be unitary matrix Q and upper triangular matrix R. decomposed, further obtains the Hermitian conjugate ^{R H} of the upper triangular matrix R (a lower triangular matrix), the interference matrix ^{B = (diagR H) -1 R} H -I representing the gain of the MUI between the respective radio receiving apparatus 200 It is obtained and output to the interference component calculation unit 603, and the unitary matrix Q is output to the linear filter unit 605. Note that diagX is a matrix having only the diagonal component of the matrix X, and I represents a unit matrix. Here, the interference matrix B takes the form of equation (2).

The first modulo calculation unit 607a performs modulo calculation on the modulation symbol addressed to the first radio reception device 200 generated by the modulation unit 321. Note that, since there is no MUI for the modulation symbol addressed to the first radio reception apparatus 200, the interference component subtraction unit 609 is omitted. Further, the modulo operation unit 607 can be omitted. Based on the interference matrix B obtained by the QR decomposition unit 601, the interference component calculation unit 603 determines that the modulo operation result of the modulation symbol of each subcarrier addressed to the first radio reception device 200 is addressed to the second radio reception device 200. The interference component given to the modulation symbol of each subcarrier is calculated. Here, the element b _{21 in} the second row and first column of the interference matrix B represents the complex gain of interference that the modulation symbol addressed to the first radio reception apparatus 200 has on the modulation symbol addressed to the second radio reception apparatus 200. The interference component can be calculated by multiplying this element by the modulo calculation result of the modulation symbol addressed to the first radio reception apparatus 200.

  The first interference component subtraction unit 609b applies the modulation symbol addressed to the second radio reception device 200 calculated by the interference component calculation unit 603 from the modulation symbol addressed to the second radio reception device 200 generated by the modulation unit 321. The interference component is subtracted for each subcarrier. The second modulo operation unit 607b performs modulo operation on the modulation symbol addressed to the second radio reception apparatus 200 from which the interference component has been subtracted, using a modulo width predetermined by the modulation scheme.

The interference component calculation unit 603 obtains the third modulo calculation result of the modulation symbol of each subcarrier addressed to the first radio reception apparatus 200 and the third modulo calculation result of the modulation symbol of each subcarrier addressed to the second radio reception apparatus 200. The interference component given to the modulation symbol of each subcarrier addressed to the wireless receiver 200 is calculated. Here, the element b _{31 in} the third row and the first column of the interference matrix B represents the complex gain of interference that the modulation symbol addressed to the first radio reception apparatus 200 exerts on the modulation symbol addressed to the third radio reception apparatus 200, and the interference 3 row and second column of elements b ₃₂ of the matrix B is represents the complex gains of the interference modulation symbols of the second radio receiver 200 addressed exerts the modulation symbols of the third wireless reception device 200 destined, these elements The interference component can be calculated by multiplying the modulo calculation result of the modulation symbol addressed to the first radio reception apparatus 200 and the modulo calculation result of the modulation symbol addressed to the second radio reception apparatus 200, respectively.

  The second interference component subtraction unit 609c applies the modulation symbol addressed to the third radio reception device 200 calculated by the interference component calculation unit 603 from the modulation symbol addressed to the third radio reception device 200 generated by the modulation unit 321. The interference component is subtracted for each subcarrier. The third modulo operation unit 607c performs modulo operation on the modulation symbol addressed to the third radio reception apparatus 200 from which the interference component has been subtracted, using a modulo width predetermined by the modulation scheme.

Interference component calculation section 603 obtains the modulo operation result of the modulation symbol of each subcarrier addressed to first radio reception apparatus 200, the modulo operation result of the modulation symbol of each subcarrier addressed to second radio reception apparatus 200, and the third The interference component given to the modulation symbol of each subcarrier addressed to the fourth radio reception apparatus 200 by the modulo calculation result of the modulation symbol of each subcarrier addressed to the radio reception apparatus 200 is calculated. Here, the element b _{41 in} the fourth row and the first column of the interference matrix B represents the complex gain of interference that the modulation symbol addressed to the first radio reception apparatus 200 exerts on the modulation symbol addressed to the fourth radio reception apparatus 200, and Element b _{42 in} the 4th row and 2nd column of matrix B represents the complex gain of interference that the modulation symbol addressed to second radio reception apparatus 200 has on the modulation symbol addressed to fourth radio reception apparatus 200, and 4 of interference matrix B elements b ₄₃ row third column represents the complex gains of the interference modulation symbols of the third wireless reception device 200 destined exerts the modulation symbols of the fourth wireless reception device 200 destined, first each of these elements The interference component can be calculated by multiplying the modulo calculation result of the modulation symbol addressed to the third radio reception apparatus 200 by the modulo calculation result of the modulation symbol addressed to the third radio reception apparatus 200.

  The third interference component subtraction unit 609d applies the modulation symbol addressed to the fourth radio reception device 200 calculated by the interference component calculation unit 603 from the modulation symbol addressed to the fourth radio reception device 200 generated by the modulation unit 321. The interference component is subtracted for each subcarrier. The fourth modulo operation unit 607d performs modulo operation on the modulation symbol addressed to the fourth radio reception apparatus 200 from which the interference component has been subtracted, using a modulo width predetermined by the modulation scheme.

  The linear filter unit 605 outputs the modulo calculation result of the modulation symbol addressed to the first radio reception device 200 output from the first modulo calculation unit 607a and the second radio reception device 200 output from the second modulo calculation unit 607b. Modulo calculation result of the modulation symbol, the modulo calculation result of the modulation symbol addressed to the third radio receiving apparatus 200 output by the third modulo calculation unit 607c, and the fourth radio signal output by the fourth modulo calculation unit 607d. Multi-user MIMO to be transmitted from each antenna of the antenna unit 303 by multiplying the unitary matrix Q calculated by the QR decomposition unit 601 as a linear filter for each subcarrier using the modulo operation result of the modulation symbol addressed to the receiving apparatus 200 as an input Output symbols.

  As a result, when each radio receiving apparatus 200 receives the multi-user MIMO symbol, interference (MUI) caused by signals other than the own radio receiving apparatus is canceled by THP, and only the signal addressed to the own radio receiving apparatus is received. . In this embodiment, a method using QR decomposition of a channel matrix has been described as an example of a method for realizing THP. However, the present invention is not limited to this, and a method of V-BLAST (Vertical Bell Laboratories Layered Space Time) is used. A method described in Non-Patent Document 5 or the like that uses the sub-optimization of the rearrangement of the wireless reception device 200 in THP may be used.

  FIG. 6A is a functional block diagram showing a wireless receiver 200a that is a configuration example of the wireless reception device 200 according to the first embodiment of the present invention. The wireless reception device 200a in FIG. 6A is an example of a nonlinear wireless reception device that supports both linear precoding and nonlinear precoding (THP) precoding schemes. The wireless reception unit 701 receives a signal from the wireless transmission device 100 through the antenna unit 703. The configuration information acquisition unit 705 acquires group configuration information notified from the wireless transmission device 100 and outputs the group configuration information to the group storage unit 707. The group storage unit 707 stores the group configuration information acquired by the configuration information acquisition unit 705. The identification information acquisition unit 709 acquires group identification information (group ID) notified from the wireless transmission device 100 and outputs the group identification information (group ID) to the determination unit 711a. Further, when the MCS information is included in the group identification information, the MCS information is output to the modulo arithmetic unit (which constitutes a reception processing unit together with the demodulator described later) 713, the demodulator 715a, and the decoder 717.

  The determination unit 711a refers to the group configuration information stored in the group storage unit 707 and determines whether or not the own wireless reception device (own station) belongs to the group indicated by the group ID acquired by the identification information acquisition unit 709. Then, the determination result is notified to the control unit 719, and when belonging to the group, the following data reception operation is executed through the control unit 719. Further, it is determined whether the group indicated by the acquired group ID is a group that performs multiuser MIMO by linear precoding or a group that performs multiuser MIMO by nonlinear precoding. In the case of linear precoding, no modulo operation is performed. In the case of nonlinear precoding, a signal for instructing the modulo arithmetic unit 713 to generate a modulo arithmetic is generated. The GI removal unit 721 removes the guard interval (GI) from the received signal.

  The FFT unit 723 performs time-frequency conversion on the received signal from which the GI has been removed by fast Fourier transform (FFT) or the like, and converts it into modulation symbols for each subcarrier. The reference signal separation unit 725 separates the modulation symbol into a received data symbol and a reference signal symbol, and inputs the received data symbol to the propagation path compensation unit 727 and the reference signal symbol to the propagation path estimation unit 729, respectively. To do. The propagation path estimation unit 729, based on the separated reference signal symbols, the propagation path state (complex propagation path gain) between each antenna of the wireless transmission device 100 and the antenna unit 703 of the wireless reception device 200a, The reception quality represented by SNR or SINR is estimated. The propagation path compensation unit 727 performs propagation path compensation (equalization) on the received data symbol based on the propagation path state estimation result in the propagation path estimation unit 729.

  The modulo calculation unit 713 receives a modulation method (identification) for a reception data symbol that has been subjected to propagation path compensation when a reception data symbol that has undergone propagation path compensation is input and an instruction signal for performing modulo operation is input from the determination unit 711a. When MCS information is input from the information acquisition unit 709, an instruction signal that performs modulo operation using a predetermined modulo operation width (modulo width) according to the MCS modulation method and does not perform modulo operation Is input, the propagation data compensated received data symbol is output as it is. Demodulation section 715a demodulates each received data symbol output from modulo operation section 713 (based on the MCS modulation scheme when identification information acquisition section 709 receives MCS information).

  Decoding section 717 performs error correction decoding processing on the demodulated sequence to generate and output a received data sequence. When MCS information is input from the identification information acquisition unit 709, rate matching (depuncture) is performed according to the coding rate of the MCS. Based on the estimated propagation path state, the propagation path information generation unit 731 receives reception quality information (CQI) representing SNR, SINR, CNR, and CINR or values calculated therefrom, and each transmission antenna of the wireless transmission device 100 To CSI representing the complex channel gain from the radio reception apparatus 200 to each reception antenna, the covariance value, and the like. The wireless transmission unit 733 transmits the propagation path information generated by the propagation path information generation unit 731 to the wireless transmission device 100 through the antenna unit 703. The control unit 719 controls each of the above units and executes each process.

  In the present embodiment, the radio receiving apparatus, prior to demodulation (determination of received signal points) in the demodulation unit 715a, when the determination unit 711a determines that the group performs multi-user MIMO by nonlinear precoding. The example of the configuration in which the modulo operation unit 713 performs the modulo operation on the received data symbol subjected to propagation path compensation has been described. A configuration example of another wireless receiving apparatus is shown in FIG. 6B.

  The wireless reception device 200b in FIG. 6B does not include the modulo arithmetic unit 713, unlike the wireless reception device 200a in FIG. 6A. When demodulating section 715b is determined to be a group that performs multi-user MIMO by nonlinear precoding in determining section 711b, the candidate signal point arrangement of the received signal is determined based on the influence of modulo operation in the wireless transmitting apparatus. From the Euclidean distance between the received signal point (added with noise) and each candidate signal point repeated with the modulo width, taking into account that the signal point arrangement at the time of modulation is repeated with a modulo width. A log Likelihood Ratio (LLR) of bits is calculated (demodulation processing by soft decision). The LLR is input to the decoding unit 717, and error correction decoding is performed. Here, the calculation of the LLR in the demodulator 715b can be calculated by, for example, a known method described in Expression (15) to Expression (20) of Non-Patent Document 6. That is, it can be calculated using an algorithm that calculates the LLR using the Euclidean distance between the received signal point and the candidate signal point close to the received signal point among the candidate signal points repeated with a modulo width. This configuration can be similarly applied to the wireless reception devices of the following embodiments.

  FIG. 6C is a functional block diagram showing a wireless reception device 200c which is another configuration example of the wireless reception device 200 according to the first embodiment of the present invention. The wireless reception device 200c in FIG. 6C is an example of a linear wireless reception device that supports only linear precoding. The wireless reception device 200c of FIG. 6C is different from the wireless reception device 200a of FIG. 6A in that the modulo arithmetic unit 713 is not provided. Also, the determination unit 711c refers to the group configuration information stored in the group storage unit 707, and whether or not the own wireless reception device (own station) belongs to the group indicated by the group ID acquired by the identification information acquisition unit 709. The control unit 719 is notified of the determination result, and if it belongs to the group, the following data reception operation is executed through the control unit 719. Note that the wireless reception device 200c does not support nonlinear precoding, and therefore does not make a determination regarding the presence or absence of modulo computation. Note that there is a linear wireless reception device (for example, conforming specification is old) that does not know that the wireless transmission device 100 of the communication partner is a wireless transmission device that supports multi-user MIMO using nonlinear precoding. Even in this case, since the wireless transmission device 100 forms a group by making the linear wireless reception device belong only to a group using linear precoding, even in such a linear wireless reception device, no special processing is added. The multi-user MIMO signal using linear precoding can be received only by determining whether or not the own radio receiving apparatus (own station) belongs to the group indicated by the group ID acquired by the identification information acquisition unit 709. Other operations are the same as those of the wireless reception device 200a.

  FIG. 7 is a diagram illustrating an example of group information created by the group configuration unit 307 of the wireless transmission device 100 and shared with the wireless reception devices 200a or 200b and 200c in the first embodiment of the present invention. In FIG. 7, when the group ID is represented by 6 bits (0 to 63), the first group using linear precoding is defined up to 31 and the second group using non-linear precoding is defined from the 32nd onward. An example is shown. Note that group IDs 0 and 63 are not used as multi-user MIMO groups, assuming that they are used as numbers indicating special purposes (for example, during single-user MIMO or before group definition). The example used is shown. For the wireless reception devices 200-1 to 200-8, linear precoding is used as a precoding method, the first group having group IDs 1 to 31 and the group ID is 32 using non-linear precoding. A second group of No. 62 is defined. Radio receivers 200-1, 200-2, 200-4, and 200-7 (wireless receivers 200 underlined in FIG. 7) that are linear radio receivers that support only linear precoding belong to the first group. Wireless receivers 200-3, 200-5, 200-6, and 200-8, which are nonlinear wireless receivers corresponding to both linear and nonlinear precoding, belong to both the first and second groups. Can do.

  8A and 8B show an example of a sequence chart showing operations between the wireless transmission device 100 and each wireless reception device 200 according to the first embodiment of the present invention. 8A and 8B, the wireless reception devices 200-1, 200-2, and 200-8 are extracted as the wireless reception device 200 and are described as representatives. Further, the group identification information will be described as being included in the control information added to the sounding signal and the multiuser MIMO signal. First, each wireless reception device 200, with respect to the wireless transmission device 100, information on the precoding scheme supported by each wireless reception device 200 (correspondence information), or type information that can identify the corresponding precoding scheme. Correspondence information based on (terminal class, compliance standard information, reception function information indicating presence / absence of modulo arithmetic function, etc.) is transmitted (step S101). Note that the transmission of the correspondence information from each wireless reception device 200 may be performed at an individual timing when communication is first established with the wireless transmission device 100 or when a request is received from the wireless transmission device 100. .

  The wireless transmission device 100 divides a group in which the wireless reception devices 200 are grouped into a plurality of groups that respectively define precoding schemes used for multiuser MIMO transmission based on correspondence information notified from the wireless reception devices 200. It creates (step S103) and notifies each wireless receiving device 200 of group information (group configuration information) (step S105). After that, radio transmitting apparatus 100 selects a group that performs multi-user MIMO transmission (step S107), generates a sounding signal that includes the group ID for identifying the selected group in the control information (step S109), and transmits it (step S109). Step S111).

  Each wireless reception device 200 receives the above sounding signal, confirms the group ID included in the control information, determines whether or not the own wireless reception device belongs to the group (step S113), If it belongs, the propagation path state between the wireless transmission device 100 is estimated based on the reception state of the reference signal included in the sounding signal, and propagation path information representing the propagation path state estimation result is generated ( In step S115), the wireless transmission device 100 is notified (step S117). In the example of FIGS. 8A and 8B, the case where the wireless reception devices 200-2 and 200-8 belong to the group is illustrated. Further, the notification of the propagation path information is sequentially performed according to the order of each wireless reception device 200 determined in advance in the group.

  The wireless transmission device 100 receives the propagation path information notified from each wireless reception device 200 belonging to the selected group, and uses the precoding scheme defined for the group ID of the selected group to receive the received propagation information. Based on the path information, the transmission data sequence addressed to each radio receiving apparatus 200 is precoded to generate a multi-user MIMO symbol (step S119), and control information including a group ID for identifying the selected group is added. A multi-user MIMO signal is transmitted (step S121). In addition, it may be recognized as a series of sequences from the sounding signal transmission, and the group ID may not be added when the multiuser MIMO signal is transmitted.

  Each wireless reception device 200 receives the multi-user MIMO signal, confirms the group ID included in the control information, determines whether the own wireless reception device belongs to the group (step S123), and If it belongs to the group, the multi-user MIMO symbol is received, and data reception processing such as demodulation and error correction decoding is performed (step S125). When no error is detected in the received data, an acknowledgment (Acknowledgement: ACK) is notified to the wireless transmission device 100, and when an error is detected, a negative acknowledgment (Negative Acknowledgment: NAK or NACK) is notified (Step S127). ). Further, the notification of ACK and NAK is sequentially performed according to the order of each wireless reception device 200 determined in advance in the group.

  As described above, according to the present embodiment, in the wireless communication system in which the wireless transmission device 100 selects and uses either linear precoding or nonlinear precoding for each multiuser MIMO transmission, the wireless transmission device Whether the multi-user MIMO signal transmitted from 100 is linear precoding or non-linear precoding can be identified from the group ID, and can be notified to the radio reception apparatus 200 without increasing the amount of control information. It becomes possible.

  In addition, a wireless receiver 200 that does not know that the wireless transmitter 100 of the communication partner is a wireless transmitter compatible with multi-user MIMO using nonlinear precoding (for example, a linear wireless receiver with an old compliant specification). Even if such a device exists, it is only necessary to determine whether or not the own wireless receiving device (own station) belongs to the group indicated by the group ID without adding any special processing to such a wireless receiving device 200. A multi-user MIMO signal using linear precoding from the wireless transmission device 100 can be received.

(Second Embodiment)
As for the communication technique according to the present embodiment, as in the first embodiment, the wireless transmission device 100 selects a plurality of wireless reception devices 200 from the plurality of wireless reception devices 200 and performs multi-user MIMO transmission. A communication system in which MUI generated between streams addressed to radio receiving apparatus 200 is suppressed in advance by linear precoding or non-linear precoding will be described as an example. In the present embodiment, linear nonlinear mixed precoding that can select and mix linear precoding or non-linear precoding for each of a plurality of radio receiving apparatuses 200 that transmit data simultaneously in multiuser MIMO transmission. A wireless communication system using the above will be described as an example.

  In the wireless communication system according to the present embodiment, as in the first embodiment, when the wireless transmission device 100 communicates with a plurality of wireless reception devices 200 (for example, wireless reception devices 200-1 to 200-8), wireless transmission is performed. The device 100 creates a plurality of groups by a plurality of combinations of these wireless reception devices 200, and assigns a group identification number (group ID) for identifying the group. One radio receiving apparatus 200 can belong to a plurality of groups. Prior to communication, the wireless transmission device 100 receives the grouping information (information about which group each wireless reception device 200 belongs to) and information defining the processing order of the associated wireless reception device in each group prior to communication. The wireless reception device 200 is notified.

  Also in this embodiment, a first group that uses linear precoding and a second group that uses nonlinear precoding are determined in advance by the system for each group ID as a precoding method used for multiuser MIMO transmission. This is the same as in the first embodiment, but allows linear radio receivers that support only linear precoding to belong to the second group. When multi-user MIMO transmission is performed in the second group, if a linear wireless reception device belongs to the second group, no modulo operation is performed on transmission data addressed to the linear wireless reception device. As a result, non-linear precoding is performed for the non-linear radio receiving apparatus, and transmission data subjected to linear pre-coding (precoding that does not require modulo operation at the time of reception) is equivalent to multi-user for the linear radio receiving apparatus. MIMO transmission can be performed.

  Thereafter, as in the first embodiment, the wireless transmission device 100 creates a plurality of combinations of the wireless reception devices 200 (target wireless reception devices) that are the targets of multi-user MIMO transmission created above as candidates for the combinations. One of the groups is selected, and multi-user MIMO transmission is performed in which transmission data addressed to a plurality of radio receiving apparatuses 200 belonging to the selected group is spatially multiplexed in the same frequency band and simultaneously communicated. At this time, the wireless reception device 200 is notified of the group to be subjected to the multi-user MIMO transmission using a group ID for identifying the selected group. At the same time, the wireless reception device 200 can identify the precoding scheme used by the wireless transmission device 100 by the notification of the group ID.

  The configuration of the wireless transmission device 100 according to the present embodiment is the same as that of the wireless transmission device 100 of FIG. 2 of the first embodiment, and the configuration of the precoding unit 323 is different. Further, the processing in the selection unit 315 and the group configuration unit 307 is different. Hereinafter, description of the same parts as those of the first embodiment will be omitted, and different parts will be described.

  The group configuration unit 307 in the present embodiment creates a plurality of groups by a plurality of combinations of the wireless reception devices 200 based on at least the corresponding precoding scheme information of the wireless reception devices 200 output from the control information acquisition unit 305. The precoding scheme used in each group is determined, and a group ID corresponding to the determined precoding scheme is assigned. For example, in the case of the above-described 6-bit group ID, the first group using linear precoding is assigned a group ID of up to 31 and the second group using non-linear precoding is assigned 32 or later. Assign a group ID. At this time, the order of each wireless reception device 200 in each group (the order of propagation path information notification, ACK / NAK response, etc. in multiuser MIMO transmission processing, the order of individual information addressed to each wireless reception device 200 in the control signal, space Stream order, etc.).

  One radio receiving apparatus 200 can belong to a plurality of groups. Furthermore, linear radio receivers that support only linear precoding can belong to the second group. Further, grouping may be performed by further using information such as position information of each wireless reception device 200 and a result of estimating an arrival angle of a radio wave from each wireless reception device 200. In this case, for example, a group may be created between the wireless reception devices 200 that are separated from each other and the wireless reception devices 200 that are separated from each other in the radio wave arrival angle so that the correlation between the propagation paths becomes low. Further, there may be a plurality of groups having different precoding schemes and orders in the combination of the same radio receiving apparatus 200. When a plurality of groups having different precoding schemes and orders are created by combining the same wireless reception devices 200 as described above, more efficient depending on the state of the propagation path of each of the combined wireless reception devices 200 It is possible to select a group defined with a good precoding scheme or order from the plurality of groups.

  The selection unit 315 is based on the propagation path information of each wireless reception device 200 acquired by the propagation path information acquisition unit 313 and the transmission data amount and priority addressed to each wireless reception device 200 accumulated in the transmission buffer unit 317. Then, a group to which a plurality of wireless reception devices 200 multiplexed by multiuser MIMO belongs is selected from a plurality of groups stored in group storage unit 309. In addition, a precoding scheme selection signal indicating a precoding scheme determined in advance corresponding to the group ID of the selected group is output for each radio reception apparatus 200. When the selected group is the first group, the precoding scheme selection signal for each radio reception apparatus 200 is a signal for selecting linear precoding in all radio reception apparatuses 200, and the selected group is the first group. In the case of the group of 2, basically, a signal for selecting non-linear precoding is output by all the radio receiving apparatuses 200. However, even when the selected group is the second group, if the linear radio receiving apparatus belongs, a signal for selecting linear precoding is output to the linear radio receiving apparatus as a precoding scheme selection signal. To do. Further, based on the CQI from each wireless reception device 200 acquired by the propagation path information acquisition unit 313, such as a modulation scheme and a coding rate (Modulation and Coding Scheme: MCS) for transmission data addressed to each wireless reception device 200 A parameter may be selected. In the present embodiment, the second group to which the four terminals of the first to fourth wireless reception devices 200 belong is selected from the wireless reception devices 200-1 to 200-8, and the selected group includes the first group. It is assumed that a linear wireless receiver is included as the first and second wireless receivers 200, and a nonlinear wireless receiver is included as the third and fourth wireless receivers 200. Each wireless receiver 200 has one sequence (one stream). A case where data is transmitted one by one will be described.

  The precoding unit 323 has each modulation symbol addressed to a plurality of radio reception devices 200 (here, a case where the first to fourth radio reception devices 200 belong) belonging to the group selected by the selection unit 315 belong. Based on the CSI from each radio reception apparatus 200 that is input and acquired by the propagation path information acquisition unit 313, it is determined corresponding to the group ID of the group selected by the selection unit 315 for each input modulation symbol. The precoding is performed on the modulation symbol addressed to each radio reception apparatus 200 by the precoding scheme, and a multiuser MIMO symbol is generated for each of the plurality of antennas of the antenna unit 303 used for transmission. However, when the group selected by the selection unit 315 is the second group and the linear wireless reception device belongs to the group, the modulo operation is not performed on the transmission data for the linear wireless reception device. Details will be described later.

  FIG. 9 is a functional block diagram showing a precoding unit 323b which is a configuration example of the precoding unit 323 according to the second embodiment of the present invention. The precoding unit 323b includes a linear precoding unit 401, a nonlinear precoding unit 403, a mixed precoding unit 801, and a switching unit 803. The linear precoding unit 401 and the non-linear precoding unit 403 are shown in FIGS. 4 and 5, respectively, as in the first embodiment. The operation of the mixed precoding unit 801 will be described later.

  The switching unit 803 receives the linear precoding result output from the linear precoding unit 401, the nonlinear precoding result output from the nonlinear precoding unit 403, and the linear nonlinear mixed precoding result output from the mixed precoding unit 801. Is done. When the precoding scheme selection signal for each radio reception apparatus 200 input from the selection unit 315 is a signal for selecting linear precoding for all radio reception apparatuses 200, the linear precoding result output by the linear precoding unit 401 is used. If it is a signal for selecting non-linear precoding for all radio receiving apparatuses 200, the non-linear precoding result output from the non-linear precoding unit 403 is selected, and a signal for selecting linear precoding and non-linear precoding are selected. When the signals are mixed, the linear nonlinear mixed precoding result output from the mixed precoding unit 801 is selected, and the first to fourth multiuser MIMO symbols to be transmitted are output from the respective antennas of the antenna unit 303. . In addition, it is preferable that the linear precoding unit 401, the nonlinear precoding unit 403, and the mixed precoding unit 801 do not perform the processing operation when the precoding scheme selection signal does not select its own precoding scheme. As a result, power consumption can be reduced.

  FIG. 10 is a functional block diagram showing a configuration example of the mixed precoding unit 801 according to the second embodiment of the present invention. In the example of FIG. 10, based on the precoding scheme selection signal for each radio reception apparatus 200 input from the selection unit 315, for each radio reception apparatus 200, the linear precoding and the Tomlinson-Harashima pre-coding as the non-linear precoding are performed. A case will be described in which one of the coding (THP) is selected and mixed to generate a multiuser MIMO signal. The mixed precoding unit 801 in FIG. 10 performs basically the same operation as the non-linear precoding unit 403 shown in FIG. 5, but receives the precoding scheme selection signal from the selection unit 315, and the first to fourth Modulo calculation is performed in first to fourth modulo calculation units 901a to 901d (hereinafter, the first to fourth modulo calculation units 901a to 901d are also collectively referred to as modulo calculation units 901) corresponding to each wireless reception device 200. Whether or not to perform the switching is switched by a precoding method selection signal. Specifically, the modulo operation unit 901 corresponding to the radio reception apparatus 200 in which the precoding method selection signal indicates linear precoding does not perform modulo operation, and the precoding method selection signal indicates non-linear precoding. A modulo operation unit 901 corresponding to the receiving device 200 performs modulo operation. In the case of the example of the present embodiment, the first modulo arithmetic unit 901a and the second modulo arithmetic unit 901b corresponding to the first and second radio receiving apparatuses 200 respectively pass the signal as it is without performing the modulo arithmetic. The third modulo arithmetic unit 901c and the fourth modulo arithmetic unit 901d corresponding to the third and fourth radio receiving apparatuses 200 respectively perform modulo arithmetic on the signal from which the interference component is subtracted.

  In the present embodiment, as the configuration of the precoding unit 323b, a configuration including three precoding units including a linear precoding unit 401, a nonlinear precoding unit 403, and a mixed precoding unit 801 has been described. Even a configuration including only such a mixed precoding unit 801 can be realized. In this case, if the precoding scheme selection signal from selection section 315 selects linear precoding for all radio reception apparatuses 200 (modulo calculation section 901 does not perform modulo calculation), it is equivalent to linear precoding. If multi-user MIMO symbols are obtained and nonlinear precoding is selected for all radio receiving apparatuses 200 (modulo computation unit 901 performs modulo computation), multi-user MIMO symbols equivalent to nonlinear precoding are obtained.

  The configuration of the wireless reception device 200 in the present embodiment is the same as that of the first embodiment in the wireless reception device 200a (nonlinear wireless reception device) in FIG. 6A, the wireless reception device 200b (nonlinear wireless reception device) in FIG. The processing is the same as that of the receiving device 200c (linear radio receiving device), and the processing in the determination units 711a to 711c is different. Hereinafter, description of the same parts as those of the first embodiment will be omitted, and different parts will be described. The determination unit 711 a in the nonlinear wireless reception device 200 a refers to the group configuration information stored in the group storage unit 707, and the own wireless reception device (own station) is assigned to the group indicated by the group ID acquired by the identification information acquisition unit 709. It is determined whether it belongs, and the determination result is notified to the control unit 719. If it belongs to the group, the data reception operation is executed through the control unit 719. Further, it is determined whether the group indicated by the acquired group ID is a group that performs multiuser MIMO by linear precoding or a group that performs multiuser MIMO by nonlinear precoding. In the case of linear precoding, no modulo operation is performed. In the case of nonlinear precoding, a signal for instructing the modulo arithmetic unit 713 to generate a modulo arithmetic is generated.

  The determination unit 711b in the nonlinear wireless reception device 200b refers to the group configuration information stored in the group storage unit 707, and the own wireless reception device (own station) is assigned to the group indicated by the group ID acquired by the identification information acquisition unit 709. It is determined whether it belongs, and the determination result is notified to the control unit 719. If it belongs to the group, the data reception operation is executed through the control unit 719. Also, it is determined whether the group indicated by the acquired group ID is a group that performs multiuser MIMO by linear precoding or a group that performs multiuser MIMO by nonlinear precoding. In the case of linear precoding, modulo arithmetic is not considered. The demodulation unit 715b is instructed to perform demodulation processing, and in the case of nonlinear precoding, a signal instructing the demodulation unit 715b to perform demodulation processing considering that the modulo operation has been performed in the wireless transmission device 100 is generated. .

  The determination unit 711c in the linear wireless reception device 200c refers to the group configuration information stored in the group storage unit 707, and the own wireless reception device (own station) is assigned to the group indicated by the group ID acquired by the identification information acquisition unit 709. It is determined whether it belongs, and the determination result is notified to the control unit 719. If it belongs to the group, the following data reception operation is executed through the control unit 719. Note that the wireless reception device 200c does not support nonlinear precoding, and therefore does not make a determination regarding the presence or absence of modulo computation. Note that there is a linear wireless reception device (for example, conforming specification is old) that does not know that the wireless transmission device 100 of the communication partner is a wireless transmission device that supports multi-user MIMO using nonlinear precoding. Even in this case, the wireless transmission device 100 generates a multi-user MIMO signal using precoding (equivalent to linear precoding) that does not perform modulo operation regardless of which group the linear wireless reception device belongs to. Therefore, even in such a linear wireless reception device, it is determined whether or not the own wireless reception device (own station) belongs to the group indicated by the group ID acquired by the identification information acquisition unit 709 without adding special processing. Alone, a multi-user MIMO signal can be received.

  FIG. 11 is a diagram illustrating an example of group information created by the group configuration unit 307 of the wireless transmission device 100 and shared with the wireless reception devices 200a or 200b and 200c in the second embodiment of the present invention. In FIG. 11, when the group ID is represented by 6 bits (0 to 63), the first group using linear precoding is defined up to the 31st, and the second group using non-linear precoding is defined after the 32nd. An example is shown. Note that group IDs 0 and 63 are not used as multi-user MIMO groups, assuming that they are used as numbers indicating special purposes (for example, during single-user MIMO or before group definition). The example used is shown. For radio reception apparatuses 200-1 to 200-8, linear precoding is used as a precoding method, a first group having group IDs 1 to 31, a non-linear precoding is used, and group ID is 32 A second group No. 62 is defined.

  Unlike the case of the first embodiment (FIG. 7), the wireless receivers 200-1, 200-2, 200-4, and 200-7 (underlined in FIG. 7), which are linear wireless receivers that support only linear precoding. The radio receiving apparatus 200) with the symbol can also belong to the second group using nonlinear precoding. For example, in the group whose group ID is No. 33, the transmission data addressed to the wireless reception devices 200-1 and 200-7 is not subjected to modulo calculation in the wireless transmission device 100, and is transmitted to the wireless reception devices 200-3 and 200-6. The data is subjected to modulo operation in the wireless transmission device 100, and multi-user MIMO transmission is performed in which these are simultaneously spatially multiplexed.

  The wireless transmission device 100 selects a plurality of wireless reception devices 200 to be subjected to multi-user MIMO transmission based on propagation path information reported from each wireless reception device 200, and includes the plurality of wireless reception devices 200. Group to be extracted and one group is selected. Alternatively, based on the propagation path information reported from each radio reception apparatus 200, first, a group (accordingly, a precoding scheme) is selected, and the radio reception apparatus 200 belonging to the selected group is set as a target of multiuser MIMO transmission. You may choose.

  As described above, according to the present embodiment, for each multi-user MIMO transmission, the wireless transmission device 100 selects one of linear precoding, nonlinear precoding, and a mixture of linear and nonlinear precoding. In such a wireless communication system, it is possible to identify from the group ID whether the multiuser MIMO signal transmitted from the wireless transmission device 100 is linear precoding or non-linear precoding, thereby increasing the amount of control information The wireless reception device 200 can be notified without doing so. In addition, there is a linear wireless reception device (for example, conforming specification is old) that does not know that the wireless transmission device 100 of the communication partner is a wireless transmission device that supports multi-user MIMO using nonlinear precoding. Even in such a case, even in such a linear radio receiving apparatus, the radio transmitting apparatus can be determined only by determining whether or not the own radio receiving apparatus (own station) belongs to the group indicated by the group ID without adding special processing. Multi-user MIMO signals from 100 can be received. At this time, the transmission data addressed to the non-linear wireless reception apparatus corresponding to other non-linear precoding can be simultaneously spatially multiplexed using non-linear precoding.

(Third embodiment)
As for the communication technique according to the present embodiment, as in the second embodiment, the wireless transmission device 100 selects a plurality of wireless reception devices 200 from the plurality of wireless reception devices 200 and performs multi-user MIMO transmission. A communication system in which MUI generated between streams addressed to radio receiving apparatus 200 is suppressed in advance by linear precoding or non-linear precoding will be described as an example. Note that, as in the second embodiment, linear precoding and non-linear precoding can be selected and mixed for each of a plurality of radio reception apparatuses 200 that transmit data simultaneously in multiuser MIMO transmission. A wireless communication system using nonlinear mixed precoding will be described as an example.

  In the wireless communication system according to the present embodiment, as in the second embodiment, when the wireless transmission device 100 communicates with a plurality of wireless reception devices 200 (for example, wireless reception devices 200-1 to 200-8), wireless transmission is performed. The device 100 creates a plurality of groups by a plurality of combinations of these wireless reception devices 200, and assigns a group identification number (group ID) for identifying the group. One radio receiving apparatus 200 can belong to a plurality of groups. Prior to communication, the wireless transmission device 100 receives the grouping information (information about which group each wireless reception device 200 belongs to) and information defining the processing order of the associated wireless reception device in each group prior to communication. The wireless reception device 200 is notified.

  In the present embodiment, a first group using linear precoding as a precoding scheme used for multi-user MIMO transmission, a second group using nonlinear precoding, linear precoding and nonlinear precoding (explicitly). 3) A third group to be mixed is determined in advance by the system for each group ID. In addition, it is allowed that the linear radio receiving apparatus corresponding to only linear precoding belongs to the second group. The processing in the first and second groups is the same as in the second embodiment. When multi-user MIMO transmission is performed in the third group, among the wireless reception devices 200 belonging to the group, the processing order within the group is Nth (N is 1 or more and less than the number of wireless reception devices belonging to the group: Hereinafter, modulo operation is not performed on transmission data addressed to radio reception apparatus 200 up to N (referred to as a precoding threshold) (equivalent linear precoding that does not require modulo operation at the time of reception), and (N + 1) th and later Non-linear precoding is performed on the transmission data addressed to the wireless receiving apparatus 200 for performing modulo operation. However, when the linear wireless receiving device belongs to the (N + 1) th and thereafter, the modulo operation is not performed on the transmission data addressed to the linear wireless receiving device.

  As a result, the processing order within the group is fast, so that when non-linear precoding such as THP is performed, the transmission data addressed to the wireless reception device 200 with a small MUI and a small transmission power suppression effect by modulo arithmetic is obtained. Performs linear precoding, the processing order is behind, and when non-linear precoding such as THP is performed, the transmission data addressed to the wireless reception device 200 has a large MUI and a large transmission power suppression effect by modulo arithmetic. In other words, nonlinear precoding can be performed, and these can be simultaneously spatially multiplexed and transmitted in multiuser MIMO. Note that the value of N may be determined in advance by the system, for example, one half of the number of wireless reception devices 200 belonging to the group (if the number of wireless reception devices is odd, rounded down or rounded up) It is also possible to make arrangements in advance by the system.

  Thereafter, as in the second embodiment, the wireless transmission device 100 creates a plurality of combinations of the wireless reception devices 200 (target wireless reception devices) that are the targets of multi-user MIMO transmission created above as candidates for the combinations. One of the groups is selected, and multi-user MIMO transmission is performed in which transmission data addressed to a plurality of radio receiving apparatuses 200 belonging to the selected group is spatially multiplexed in the same frequency band and simultaneously communicated. At this time, the wireless reception device 200 is notified of the group to be subjected to the multi-user MIMO transmission using a group ID for identifying the selected group. At the same time, the wireless reception device 200 can identify the precoding scheme used by the wireless transmission device 100 by the notification of the group ID.

  The configuration of the wireless transmission device 100 according to the present embodiment is the same as that of the wireless transmission device 100 of the second embodiment, the precoding unit 323b is the same, and the processing in the selection unit 315 and the group configuration unit 307 is different. Hereinafter, description of the same parts as those of the second embodiment will be omitted, and different parts will be described.

  The group configuration unit 307 in the present embodiment creates a plurality of groups by a plurality of combinations of the wireless reception devices 200 based on at least the corresponding precoding scheme information of the wireless reception devices 200 output from the control information acquisition unit 305. The precoding scheme used in each group is determined, and a group ID corresponding to the determined precoding scheme is assigned. For example, in the case of the above-described 6-bit group ID, group IDs up to 20 are assigned to the first group using linear precoding, and numbers 21 to 40 are used for the second group using nonlinear precoding. No. 41 is assigned to the third group, and No. 41 and subsequent group IDs are assigned to the third group. At this time, the order of each wireless reception device 200 in each group (the order of propagation path information notification, ACK / NAK response, etc. in multiuser MIMO transmission processing, the order of individual information addressed to each wireless reception device 200 in the control signal, space Stream order, etc.). One radio receiving apparatus 200 can belong to a plurality of groups. Furthermore, linear radio receivers that support only linear precoding can belong to the second group. Further, grouping may be performed by further using information such as position information of each wireless reception device 200 and a result of estimating an arrival angle of a radio wave from each wireless reception device 200. In this case, for example, a group may be created between the wireless reception devices 200 that are separated from each other and the wireless reception devices 200 that are separated from each other in the radio wave arrival angle so that the correlation between the propagation paths becomes low. In addition, there may be a plurality of groups in which the precoding scheme and order of each wireless reception device 200 are different in the combination of the same wireless reception device 200. When a plurality of groups having different precoding schemes and orders are created by combining the same wireless reception devices 200 as described above, more efficient depending on the state of the propagation path of each of the combined wireless reception devices 200 It is possible to select a group defined with a good precoding scheme or order from the plurality of groups.

  The selection unit 315 is based on the propagation path information of each wireless reception device 200 acquired by the propagation path information acquisition unit 313 and the transmission data amount and priority addressed to each wireless reception device 200 accumulated in the transmission buffer unit 317. Then, a group to which a plurality of wireless reception devices 200 multiplexed by multiuser MIMO belongs is selected from a plurality of groups stored in group storage unit 309. In addition, a precoding scheme selection signal indicating a precoding scheme determined in advance corresponding to the group ID of the selected group is output for each radio reception apparatus 200. When the selected group is the first group, the precoding scheme selection signal for each radio reception apparatus 200 is a signal for selecting linear precoding in all radio reception apparatuses 200, and the selected group is the first group. In the case of the group of 2, basically, a signal for selecting non-linear precoding is output by all the radio receiving apparatuses 200. Further, when the selected group is the third group, as a precoding scheme selection signal for each wireless reception device 200, for the wireless reception devices 200 up to the Nth predetermined order in the group. A signal for selecting linear precoding is output, and a signal for selecting non-linear precoding is output to the (N + 1) th and subsequent radio receiving apparatuses 200. However, even when the selected group is the second group, if the linear radio receiving apparatus belongs, a signal for selecting linear precoding is output to the linear radio receiving apparatus as a precoding scheme selection signal. To do. In addition, when the selected group is the third group and the linear radio receiving apparatus belongs to the (N + 1) th or later, linear precoding is performed as a precoding scheme selection signal for the linear radio receiving apparatus. Outputs the signal to be selected.

  FIG. 12 is a diagram illustrating an example of group information created by the group configuration unit 307 of the wireless transmission device 100 and shared with the wireless reception devices 200a or 200b and 200c in the third embodiment of the present invention. In FIG. 12, the group ID is represented by 6 bits (0 to 63), the first group using linear precoding from the 20th to the second group using the nonlinear precoding from the 21st to the 40th, An example is shown in which the number 41 and beyond are defined as a third group in which linear precoding and non-linear precoding are mixed. Note that group IDs 0 and 63 are not used as multi-user MIMO groups, assuming that they are used as numbers indicating special purposes (for example, during single-user MIMO or before group definition). The example used is shown. For radio reception apparatuses 200-1 to 200-8, linear precoding is used as a precoding method, first group with group IDs 1 to 20 is used, nonlinear precoding is used, and group ID is 21 A 40th second group, a third group having a group ID of No. 41 to No. 62, which uses a mixture of linear precoding and nonlinear precoding, is defined. Here, as in FIG. 7 and FIG. 11, the underlined wireless reception device 200 is a linear wireless reception device that supports only linear precoding.

  Here, the case where the above-described precoding threshold N is 2 will be described as an example. In the third group, for example, the group whose group ID is No. 42, the radio receiving apparatuses 200-3 and 200- having the second highest order The transmission data addressed to 5 is not subjected to the modulo operation in the wireless transmission device 100, and the transmission data addressed to the wireless reception devices 200-6 and 200-8 is subjected to the modulo operation in the wireless transmission device 100, and these are spatially multiplexed simultaneously. Perform multi-user MIMO transmission. Further, when the linear wireless receiving device (wireless receiving device 200-7) belongs to the 3rd (= N + 1) th and subsequent wireless receiving devices 200 as in the group with the group ID 62, the wireless receiving device 200- The transmission data addressed to 7 is not subjected to modulo calculation in the wireless transmission device 100.

  As described above, according to the present embodiment, for each multi-user MIMO transmission, the wireless transmission device 100 selects one of linear precoding, nonlinear precoding, and a mixture of linear and nonlinear precoding. In such a wireless communication system, it is possible to identify from the group ID whether the multiuser MIMO signal transmitted from the wireless transmission device 100 is linear precoding or non-linear precoding, thereby increasing the amount of control information The wireless reception device 200 can be notified without doing so. In addition, there is a linear wireless reception device (for example, conforming specification is old) that does not know that the wireless transmission device 100 of the communication partner is a wireless transmission device that supports multi-user MIMO using nonlinear precoding. Even in such a case, even in such a linear radio receiving apparatus, the radio transmitting apparatus can be determined only by determining whether or not the own radio receiving apparatus (own station) belongs to the group indicated by the group ID without adding special processing. Multi-user MIMO signals from 100 can be received. At this time, the transmission data addressed to the non-linear wireless reception apparatus corresponding to other non-linear precoding can be simultaneously spatially multiplexed using non-linear precoding.

  Further, when nonlinear precoding such as THP is performed, linear precoding is performed on transmission data addressed to the wireless reception device 200 with a small MUI and a small transmission power suppression effect by modulo calculation, and the MUI is large. It can also be applied to multi-user MIMO transmission using precoding that can improve transmission characteristics by performing non-linear precoding on transmission data addressed to radio receiving apparatus 200 that has a large transmission power suppression effect by modulo arithmetic. .

  The program that operates in the communication apparatus according to the present invention may be a program that controls a CPU (Central Processing Unit) or the like (a program that causes a computer to function) so as to realize the functions of the above-described embodiments related to the present invention. Information handled by these devices is temporarily stored in RAM (Random Access Memory) during the processing, and then stored in various ROMs such as Flash ROM (Read Only Memory) and HDD (Hard Disk Drive). Reading, correction, and writing are performed by the CPU as necessary. 2 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed, whereby the processing of each unit is performed. May be performed. Here, the “computer system” includes an OS and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system. Further, part or all of the communication devices (wireless transmission device 100 and wireless reception device 200) in the above-described embodiment may be realized as an LSI that is typically an integrated circuit. Each functional block of the communication device may be individually chipped, or part or all of them may be integrated into a chip. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integrated circuit technology that replaces LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology can also be used.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the invention may be changed in design without departing from the gist of the present invention. Is also included. The present invention is applicable to a communication device.

100 wireless transmission device 200, 200-1 to 200-8, 200a, 200b, 200c wireless reception device 301 wireless reception unit 303 antenna unit 305 control information acquisition unit 307 group configuration unit 309 group storage unit 311 configuration information generation unit 313 propagation path Information acquisition unit 315 Selection unit 317 Transmission buffer unit 319 Encoding unit 321 Modulation unit 323, 323a, 323b Precoding unit 325 Reference signal multiplexing unit 327 IFFT unit 329 GI insertion unit 331 Identification information generation unit 333 Radio transmission unit 335 Control unit 401 Linear precoding unit 403 Nonlinear precoding unit 405 Switching unit 501 Filter calculation unit 503 Linear filter unit 601 QR decomposition unit 603 Interference component calculation unit 605 Linear filter units 607, 607a, 607b, 607c, 607d Modulo Arithmetic units 609, 609b, 609c, 609d Interference component subtraction unit 701 Radio reception unit 703 Antenna unit 705 Configuration information acquisition unit 707 Group storage unit 709 Identification information acquisition units 711a, 711b, 711c Determination unit 713 Modulo calculation units 715a, 715b, 715c Demodulation unit 717 Decoding unit 719 Control unit 721 GI removal unit 723 FFT unit 725 Reference signal separation unit 727 Channel compensation unit 729 Channel estimation unit 731 Channel information generation unit 733 Wireless transmission unit 801 Mixed precoding unit 803 switching unit 901 , 901a, 901b, 901c, 901d Modulo arithmetic unit

Claims (11)

A wireless transmission device that includes a plurality of transmission antennas and performs multi-user MIMO transmission that simultaneously transmits transmission data addressed to a plurality of wireless reception devices by spatial multiplexing,
A plurality of groups representing a combination of the plurality of radio receiving apparatuses when performing multi-user MIMO transmission is created, and a precoding scheme is determined in advance as either linear precoding or non-linear precoding for each group. A group configuration unit for determining each group identification number based on the determined precoding scheme for each group, from among group identification number candidates predetermined corresponding to the coding scheme;
A configuration information generating unit that generates group configuration information for notifying the plurality of wireless reception devices of the configuration and identification number for each of the plurality of groups;
A selection unit for selecting any one group from the plurality of groups,
An identification information generating unit for generating group identification information for notifying the identification number of the selected group;
A precoding unit that performs precoding with respect to transmission data addressed to a wireless reception device belonging to the selected group, in a precoding scheme determined in advance for an identification number assigned to the selected group; Bei example,
Prior to transmission of the precoded signal, the group configuration information is transmitted to the plurality of radio reception apparatuses in advance, and the group identification information is transmitted together with the precoded signal to each radio reception apparatus belonging to the selected group. radio transmitting apparatus characterized that you send to. The precoding unit transmits a signal to a radio reception apparatus belonging to the selected group when the precoding method determined in advance for the identification number assigned to the selected group is nonlinear precoding. 2. The radio transmission apparatus according to claim 1 , wherein modulo operation is performed on the radio transmission apparatus. The precoding unit is configured to perform wireless reception in which the precoding method determined in advance for the identification number assigned to the selected group is nonlinear precoding, and the selected group corresponds to only linear precoding. The radio transmission apparatus according to claim 2 , wherein when the apparatus belongs, a modulo operation is not performed on a signal transmitted to the radio reception apparatus corresponding to only the linear precoding . For each group, the group configuration unit adds a precoding method to linear precoding and non-linear precoding, and linear non-linear precoding in which linear precoding and non-linear precoding are mixed. Predetermining, and further determining in advance the order within each group of wireless reception devices belonging to each group,
The precoding unit, in a case where a precoding scheme determined in advance for the identification number assigned to the selected group is linear nonlinear mixed precoding, is pre-selected among radio receiving apparatuses belonging to the selected group. A modulo operation is not performed on a signal transmitted to a wireless reception device in an order before a predetermined threshold, and a modulo operation is performed on a signal transmitted to a wireless reception device in an order after the threshold. The wireless transmission device according to claim 1 . In the precoding unit, the precoding method determined in advance for the identification number assigned to the selected group is linear nonlinear mixed precoding, and the radio receiving apparatus belonging to the selected group When the wireless receivers in order after the threshold include wireless receivers that support only linear precoding, modulo operation is not performed on signals transmitted to the wireless receivers that support only linear precoding. The wireless transmission device according to claim 4 . Wherein the plurality of groups, from claim 1, characterized in that has a plurality of radio receiving apparatus of the same combination belongs, and the order in the belonging group of the plurality of radio receiving apparatus includes a plurality of different groups The wireless transmission device according to claim 5 . A wireless reception device that receives a multi-user MIMO signal in which transmission data addressed to a plurality of wireless reception devices is spatially multiplexed and transmitted simultaneously from a wireless transmission device having a plurality of transmission antennas,
Configuration information for receiving and acquiring group configuration information for notifying the configuration of the group to which the plurality of radio receiving apparatuses to which the multi-user MIMO signal is transmitted belongs and the identification number of the group prior to the reception of the multi-user MIMO signal An acquisition unit;
An identification information acquisition unit that receives and acquires group identification information that reports the identification numbers of the groups to which the plurality of wireless reception devices to which the multi-user MIMO signal is transmitted from the wireless transmission device together with the multi-user MIMO signal When,
A determination unit for determining whether the own device belongs to the group indicated by the identification number;
As a result of the determination, if the own apparatus belongs to the group indicated by the identification number, either linear precoding or nonlinear precoding predetermined for the identification number is applied to the received multiuser MIMO signal. A radio reception apparatus comprising: a reception processing unit that performs reception processing according to one precoding scheme. The radio reception apparatus according to claim 7, wherein the reception processing unit performs a modulo operation on the received data symbol when the precoding scheme is nonlinear precoding . The precoding method determined in advance for the identification number is one of linear non-linear mixed precoding in which linear precoding and non-linear precoding are mixed in addition to linear precoding and non-linear precoding,
The reception processing unit performs a modulo operation on a received data symbol when the precoding scheme is linear nonlinear mixed precoding and the order of the own apparatus determined in the group is after a predetermined threshold. The radio reception apparatus according to claim 7 or 8, wherein the radio reception apparatus is performed. The wireless transmission device is mounted on a wireless transmission device having a plurality of transmission antennas.
An integrated circuit that performs a plurality of functions,
A plurality of groups representing a combination of a plurality of radio receiving apparatuses when performing multi-user MIMO transmission are created, and a precoding method is determined in advance as either linear precoding or non-linear precoding for each group, and precoding is performed. A function for determining each group identification number based on the determined precoding scheme for each group, from among group identification number candidates predetermined according to the scheme;
A function of generating group configuration information for notifying the plurality of wireless reception devices of the configuration and identification number for each of the plurality of groups;
A function of selecting any one group from the plurality of groups;
A function of generating group identification information for notifying the identification number of the selected group;
A function of performing precoding with respect to transmission data addressed to a wireless reception device belonging to the selected group by a precoding method determined in advance corresponding to an identification number assigned to the selected group;
Prior to transmission of the precoded signal, the group configuration information is transmitted to the plurality of radio reception apparatuses in advance, and the group identification information is transmitted together with the precoded signal to each radio reception apparatus belonging to the selected group. An integrated circuit characterized by causing the wireless transmission device to exhibit a series of functions including: An integrated circuit that, when mounted on a wireless receiver, causes the wireless receiver to perform a plurality of functions,
A function of receiving, from a wireless transmission device having a plurality of transmission antennas, a multiuser MIMO signal in which transmission data addressed to a plurality of wireless reception devices is spatially multiplexed and transmitted simultaneously;
A function of receiving and acquiring group configuration information for notifying a configuration of a group to which the plurality of radio receiving apparatuses to which the multi-user MIMO signal is transmitted belongs and a group identification number, prior to the reception of the multi-user MIMO signal; ,
A function of receiving and acquiring group identification information for notifying the identification number of a group to which the plurality of radio receiving apparatuses to which the multi-user MIMO signal is transmitted from the radio transmitting apparatus together with the multi-user MIMO signal;
A function of determining whether the own device belongs to the group indicated by the identification number;
As a result of the determination, if the own apparatus belongs to the group indicated by the identification number, either linear precoding or nonlinear precoding predetermined for the identification number is applied to the received multiuser MIMO signal. An integrated circuit characterized by causing the radio receiving apparatus to exhibit a series of functions of receiving a signal addressed to its own apparatus according to one precoding method.

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