Multi-cell cooperative communication system and terminal device

Multi-cell cooperative communication system and terminal device

1The present invention relates to a multi-cell cooperative communication system and a terminal device, and more particularly, to a multi-cell cooperative communication system and a terminal device that enables a plurality of base station devices to cooperate with each other to perform MIMO communication with the terminal device.

2In general, a terminal device located at a cell boundary is transmitted from a neighbor cell base station device that controls a neighbor cell adjacent to a serving cell as well as a data signal transmitted from the base station device of its serving cell. The signal is affected.

3In general cellular communication, since the data signal transmitted from the neighboring cell base station device acts as an interference to the data signal transmitted from the serving cell base station device, the data signal transmitted from the neighboring cell base station device The greater the interference, the more there is a limit to increasing the data rate.

4In this case, if the data signal transmitted from the neighbor cell base station device becomes a data signal for the terminal device, the data transmission rate can be improved compared to the case of transmitting the data signal using a general cellular communication method. As described above, a method in which a plurality of base station devices cooperate with each other to perform data communication with a terminal device is called multi-cell cooperation communication.

<p num="5">An object of the present invention is to provide a multi-cell cooperative communication system that enables a plurality of cells to perform multi-antenna communication with a terminal device in cooperation with each other.</p>

<p num="6">A multi-cell cooperative communication system according to an embodiment of the present invention includes at least one first antenna, and transmits a data signal to a terminal device having at least one second antenna using the at least one first antenna A plurality of base station devices, each of the plurality of base station devices includes the same codebook, and precoding at least one data symbol based on the codebook to generate a data signal and using the same radio resource. To transmit the data signal to the terminal device. </p><p num="7">In addition, the multi-cell cooperative communication system according to an embodiment of the present invention includes at least one first antenna, and is transmitted from a terminal device having at least one second antenna using the at least one first antenna. A plurality of base station devices for receiving a data signal, the plurality of base station devices includes a serving cell base station device and at least one neighbor cell base station device, the serving cell base station device receives a first data signal, the At least one neighboring cell base station apparatus receives a second data signal, and the at least one neighboring cell base station apparatus is configured to receive at least one of information regarding the second data and the second data signal restored from the second data signal. A serving cell base station apparatus, and the serving cell base station apparatus recovers first data from the first data signal using at least one of the second data and the information about the second data signal. </p><p num="8">In addition, the terminal device according to an embodiment of the present invention, a storage unit for storing a codebook including at least one precoding matrix consisting of a plurality of precoding vectors, a receiving unit for receiving a radio signal from the plurality of base station devices, A channel estimator for estimating states of a plurality of channels formed between the plurality of base station devices and the terminal device based on the radio signal, and one of the at least one precoding matrix based on the estimated states of the plurality of channels And a selection unit for selecting a precoding matrix of and selecting at least one precoding vector among a plurality of precoding vectors constituting the one precoding matrix, and information on the selected at least one precoding vector. And a transmitting unit transmitting the second feedback signal to at least one base station apparatus among the plurality of base station apparatuses.</p><p num="9">According to the present invention, multiple cells can cooperate with each other to perform multi-antenna communication with a terminal device.</p>

101 is a diagram illustrating a concept of downlink multi-cell cooperative communication involving two base station devices according to an embodiment of the present invention.

112 is a view for explaining a method of configuring a supercell based on the location of a terminal device.

123 is a view for explaining a method of configuring a fixed form of a super cell regardless of the position of the terminal device.

134 is a diagram illustrating the concept of uplink multi-cell cooperative communication involving three base station devices according to an embodiment of the present invention.

145 is a block diagram showing a detailed configuration of a terminal device according to an embodiment of the present invention.

15Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited or limited by the embodiments. The same reference numerals in each drawing denote the same members.

16A plurality of base station devices constituting a multi-cell cooperative communication system may include a relay node as well as a base station device that controls a conventional cell such as a macro cell or a micro cell. Accordingly, the multi-cell cooperative communication system according to an embodiment of the present invention can be applied to various types of cooperative communication, such as cooperative communication by conventional cells, cooperative communication of relay nodes, and cooperative communication of conventional cells and relay nodes. .

17In general, one physical base station device can control more than one cell. In the present invention, the term base station apparatus will be used as a concept corresponding to one cell. Accordingly, even when one base station device physically manages a plurality of cells, it is assumed that there are as many logical base station devices as there are cells, and there is one logical base station device that controls each cell. Hereinafter, the term base station apparatus referred to in the present invention refers to the above logical base station apparatus, and thus governs one cell.

191 is a diagram illustrating a concept of downlink multi-cell cooperative communication involving two base station devices according to an embodiment of the present invention.

20In FIG. 1, although there are two base station devices involved in downlink communication (that is, a multi-cell cooperative communication system includes two base station devices), a multi-cell cooperative communication system according to an embodiment of the present invention It can be said to those skilled in the art that it may include three or more base station devices.

21In the multi-cell cooperative communication system according to an embodiment of the present invention, both the serving cell base station device 120 and the neighboring cell base station device 130 transmit data signals required by the terminal device 110 to the terminal device 110. , Improve the data transfer rate.

22In this case, each of the serving cell base station apparatus 120 and the neighboring cell base station apparatus 130 includes at least one first antenna (that is, a transmission antenna), and the terminal device 110 has at least one second antenna (that is, , Receiving antenna) (in FIG. 1, the serving cell base station apparatus 120 and the neighboring cell base station apparatus 130 are illustrated as having four first antennas). Accordingly, each of the serving cell base station apparatus 120 and the neighbor cell base station 130 transmits a data signal to the terminal apparatus 110 using at least one first antenna, and the terminal apparatus 110 has at least one second. A data signal is received using an antenna. That is, the terminal device 110, the serving cell base station device 120, and the neighbor cell base station device 130 perform multi-in multi-out (MIMO) communication through multi-cell cooperation using a plurality of antennas.

23Hereinafter, a downlink MIMO communication in which a plurality of base station devices having at least one first antenna transmit data signals to a terminal device having at least one second antenna in cooperation with each other will be described in more detail.

24In order to perform multi-cell cooperative MIMO communication in downlink, a plurality of base station devices generate data signals by precoding data symbols to be transmitted using the same codebook, and generate the same data signals. The data signal generated using the resource is transmitted to the terminal device 110. In this case, a method of precoding data symbols using a codebook can be classified into two methods as described below.

26<u style="single">One. Joint codebook method</u>

28The joint codebook method considers a plurality of cells controlled by a plurality of base station devices involved in cooperative communication as one virtual cell, and includes at least one first antenna provided in the plurality of base station devices and at least one product provided in the terminal device. It means a method of performing MIMO communication using 2 antennas.

29Since a plurality of cells are regarded as one virtual cell, the terminal device having at least one second antenna performs MIMO communication with one virtual cell base station device having a plurality of first antennas managing the virtual cell. Can be considered.

30Accordingly, the size of at least one precoding matrix included in the codebook is determined according to the sum of the number of first antennas provided in each of the plurality of base station devices.

31That is, when the sum of the number of first antennas provided in each of a plurality of base station devices involved in cooperative communication is N (N is a predetermined integer greater than or equal to 1), the precoding matrix included in the codebook has a size of N×N. Have In addition, the precoding matrix is ​​composed of a plurality of precoding vectors. The precoding vector means each column vector of the precoding matrix. In this case, the precoding matrix can be expressed as Equation 1 below.

32[Equation 1]

33<img file="WO2010143780A2_D0001.tif" />

34here, <img file="WO2010143780A2_D0002.tif" />Is the precoding matrix, <img file="WO2010143780A2_D0003.tif" /> To <img file="WO2010143780A2_D0004.tif" />Is the element of the precoding matrix, <img file="WO2010143780A2_D0005.tif" /> To <img file="WO2010143780A2_D0006.tif" />Means each precoding vector. The codebook includes one or more precoding matrices as described above.

35Hereinafter, an operation of generating a data signal by precoding at least one data symbol by a plurality of base station devices based on the joint codebook method and transmitting the data signal to the terminal device 110 will be described in detail.

36First, a plurality of base station devices select one precoding matrix to be used for transmission of a data signal from among a plurality of precoding matrices included in the codebook. In this case, each of the plurality of base station devices selects the same precoding matrix. Hereinafter, a precoding matrix represented by Equation 1 above<img file="WO2010143780A2_D0007.tif" />It is assumed that is selected.

37Next, a plurality of base station devices are selected precoding matrix <img file="WO2010143780A2_D0008.tif" />At least one precoding vector is selected from a plurality of precoding vectors constituting. Hereinafter, it is assumed that the number of selected precoding vectors is M (M is a predetermined integer of 1 or more and N or less).

38Since one precoding vector is used to precode one data symbol, the number of selected precoding vectors is the same as the number of data symbols to be transmitted from a plurality of base station devices to a terminal device .

39A data signal transmitted by the i-th antenna among N first antennas provided in a plurality of base station devices (that is, provided in a virtual cell base station device that controls a virtual cell) is transmitted. <img file="WO2010143780A2_D0009.tif" />, Select M precoding vectors <img file="WO2010143780A2_D0010.tif" />, To transmit the data symbol <img file="WO2010143780A2_D0011.tif" />Speaking of, the data signal transmitted from the N first antennas can be expressed as Equation 2 below.

40[Equation 2]

41<img file="WO2010143780A2_D0012.tif" />

42Finally, a plurality of base station devices are N precoded data signals <img file="WO2010143780A2_D0013.tif" /> To <img file="WO2010143780A2_D0014.tif" />Is transmitted to the terminal device at the same time using the same radio resource. That is, the N precoded data signals are transmitted to the terminal device using one OFDM subcarrier.

43In addition, for channel estimation in a terminal device, according to an embodiment of the present invention, each of the plurality of base station devices uses a reference (using a plurality of precoding vectors identical to the plurality of precoding vectors used for precoding data signals) reference) the signal may be precoded and the precoded reference signal may be transmitted to the terminal device. In this case, since the data signal and the reference signal are precoded using the same plurality of precoding vectors, the terminal device can easily perform estimation of a channel formed between itself and a plurality of base station devices. The precoded reference signal is transmitted by being located only in a resource block allocated to the terminal device 110.

45<u style="single">2. Cell-by-cell codebook method</u>

47The cell-specific codebook method refers to a method of generating a data signal by precoding the same data symbol with the same precoding vector in each of a plurality of base station devices involved in cooperative communication, and transmitting the generated data signal to a terminal device. In this case, each of the plurality of base station devices performs MIMO communication by transmitting a data signal to a terminal device having a plurality of second antennas (ie, receiving antennas) using at least one first antenna (ie, transmitting antennas). do.

48Accordingly, the size of at least one precoding matrix included in the codebook is determined according to the number of at least one first antenna provided in each of the plurality of base station devices. That is, when the number of first antennas provided in each of a plurality of base stations involved in cooperative communication is N, the precoding matrix included in the codebook has a size of N×N. In this case, the precoding matrix can be expressed as Equation 1 above, similar to the joint codebook method mentioned above.

49Hereinafter, an operation of generating a data signal by precoding at least one data symbol based on a codebook method for each cell in each of a plurality of base station apparatuses and transmitting them to a terminal apparatus will be described in detail step by step.

50First, each of the plurality of base station devices selects one precoding matrix to be used for transmission of a data signal from among a plurality of precoding matrices included in the codebook. Each of the plurality of base station devices may select a different precoding matrix. However, when the base station takes precoding information from the feedback of the terminal device, a restriction may be placed on each of the plurality of base station devices to select the same precoding matrix to reduce the amount of feedback.

52Hereinafter, a precoding matrix as in Equation 1 above <img file="WO2010143780A2_D0015.tif" />It is assumed that is selected. Next, the precoding matrix selected in each of the plurality of base station devices<img file="WO2010143780A2_D0016.tif" />At least one precoding vector is selected from a plurality of precoding vectors included in. Each of the plurality of base station devices can generally select a different precoding vector. However, in order to reduce the amount of feedback when precoding information is taken from the feedback of the terminal device, a restriction may be applied so that each of the plurality of base station devices selects the same precoding vector.

53In addition, data symbols transmitted from each of the plurality of base station devices are the same data symbols. That is, each of the plurality of base station devices generates a data signal by precoding the same data symbol using the selected precoding vector, and transmits the generated data signal to the terminal device. Hereinafter, it is assumed that the number of selected precoding vectors and the number of data symbols to be transmitted are M.

54Among the N first antennas provided in each of the plurality of base station devices, a data signal transmitted by the i-th antenna is transmitted. <img file="WO2010143780A2_D0017.tif" />, Select M precoding vectors <img file="WO2010143780A2_D0018.tif" />, To transmit the data symbol <img file="WO2010143780A2_D0019.tif" />If indicated, in each of the plurality of base station devices, N data signals transmitted through N first antennas may be expressed as Equation 2 above.

55Finally, each of the plurality of base station devices has N precoded data signals <img file="WO2010143780A2_D0020.tif" /> To <img file="WO2010143780A2_D0021.tif" />Is transmitted to the terminal device at the same time using the same radio resource. That is, each of the plurality of base station apparatuses simultaneously transmits N precoded data signals using one carrier.

56In addition, even in the case of a cell-by-cell codebook method, each of the plurality of base station devices is used to precode a data signal so that the estimation of a channel formed between the terminal device and the plurality of base station devices can be easily performed. A reference signal may be precoded using a plurality of precoding vectors identical to the vector, and the precoded reference signal may be transmitted to the terminal device. The precoded reference signal is transmitted by being located in a resource block allocated to the terminal device.

58In the above, a joint codebook method and a cell-specific codebook method for generating a data signal by precoding data symbols and transmitting the generated data signal to a terminal device have been described. Hereinafter, control operations of a plurality of base station apparatuses that are equally applied to the joint codebook method and the cell-specific codebook method will be described.

59According to an embodiment of the present invention, a plurality of base station devices may exchange information about radio resources and precoding information for selecting a precoding matrix and a precoding vector. This is to enable selection of the same precoding matrix, the same precoding vector, and the same radio resource in each of a plurality of base station devices.

60In this case, each of the plurality of base station devices precodes at least one data symbol based on the pre-exchanged precoding information and uses the radio resource used for transmission of the data signal based on the information on the exchanged radio resource. Can decide.

61Communication between a plurality of base station devices may be performed using a backbone network connected to a network, a dedicated line directly connecting the base station devices, and wireless communication. When a plurality of base station devices exchange information through wireless communication, the plurality of base station devices may use a part of a frequency band used for communication between the base station device and the terminal device, or a frequency used for communication between the base station device and the terminal device. Other frequency bands separate from the band may be used.

62Further, precoding information may be obtained from a terminal device. In this case, the terminal device may transmit precoding information to the serving cell base station device.

63The serving cell base station device receiving the precoding information from the terminal device may select a precoding matrix and a precoding vector based on the received precoding information.

64In addition, the serving cell base station apparatus transmits scheduling information including at least one of received precoding information, information on radio resources allocated to the terminal device, and modulation and coding scheme (MCS) information to a neighbor cell base station apparatus. Can transmit.

65In this case, the neighbor cell base station device may generate a data signal based on the scheduling information and transmit the generated data signal to the terminal device. That is, the neighbor cell base station device may transmit a data signal to the terminal device based on the scheduling information transmitted from the serving cell base station. At this time, it is preferable that the serving cell base station and the neighbor cell base station device are synchronized.

66In addition, in order to perform MIMO communication in cooperation with a plurality of base station devices, a subject who collectively directs cooperative communication performed between base station devices may be required. Accordingly, according to an embodiment of the present invention, a plurality of base station devices may be configured to include a first base station device for controlling cooperative communication and at least one second base station device controlled by the first base station device. Hereinafter, a first base station device will be referred to as a supernode, and a set of at least one cell managed by at least one second base station device will be referred to as a supercell.

67The super node determines scheduling for at least one terminal participating in the cooperative communication, and transmits the determined scheduling information for the at least one terminal to at least one second base station device that is in charge of the supercell, to thereby transmit the second base station device. It is possible to control the second base station device to transmit the data signal according to the scheduling information.

68Hereinafter, a method of configuring a super cell will be described in detail with reference to FIGS. 2 and 3.

70First, FIG. 2 is a diagram for explaining a method of configuring a supercell based on the positions of the terminal devices 210 and 220.

71According to an embodiment of the present invention, the terminal devices 210 and 220 receive radio signals from a plurality of base station devices located in their surroundings, and measure and measure the intensity of the received radio signals. Information about the size of the plurality of wireless signals may be transmitted to the super node. As an example, the wireless signal may be a reference signal.

72In this case, the super node may select at least one second base station device that controls the supercell from among the plurality of base station devices based on the information on the received size of the plurality of radio signals.

73As an example, the super node may select a base station apparatus that transmits a radio signal having a strength greater than a preset strength among a plurality of radio signals as a second base station apparatus. Accordingly, the terminal devices 210 and 220 can be guaranteed a good radio channel environment regardless of their location.

74In general, since the intensity of the radio signal is inversely proportional to the distance, the closer the position between the terminal devices 210 and 220 and the cell, the greater the intensity of the radio signal transmitted from the base station device that controls the cell. Therefore, according to an embodiment of the present invention, the super node may select at least one base station device close to the terminal devices 210 and 220 as the second base station device.

75For example, as illustrated in FIG. 2, since the terminal device 210 is located close to the cell A 230, the cell B 240, and the cell D 260, the super node is the cell A 230 , Cell B 240 and Cell D 260 may be selected as super cells for the terminal device 210.

76In addition, since the terminal device 220 is located close to the cell A 230, the cell C 250, and the cell D 260, the super node is the cell A 230, the cell C 250, and Cell D 260 may be selected as a super cell for the terminal device 220.

77Next, FIG. 3 is a view for explaining a method of configuring a fixed type supercell regardless of the location of the terminal devices 310 and 320.

78In FIG. 3, cell A 330, cell B 340, and cell C 350 constitute one supercell (hereinafter referred to as a first supercell) regardless of the location of the terminal devices 310 and 320, , Cell D 360, Cell E 370, and Cell F 380 constitute another supercell (hereinafter referred to as a second supercell). Accordingly, the terminal device 310 can receive a radio signal from the first supercell, and the terminal device 320 can receive a radio signal from the second supercell.

79Here, since the terminal device located at the boundary between the super cells, such as the terminal device 310, may receive interference by a radio signal transmitted from a neighboring super cell, inter-cell interference control is performed to alleviate interference between super cells. Can be performed. As an example, a Fractional Frequency Reuse (FFR) method may be used for interference control between supercells.

81According to an embodiment of the present invention, the super node may limit only some cells among cells belonging to the super cell controlled by itself to participate in cooperative communication.

82That is, according to an embodiment of the present invention, the super node (that is, the first base station device) selects at least one third base station device from at least one second base station device that controls at least one cell belonging to the super cell. And, only the selected third base station device can be controlled to transmit the data signal to the terminal device. In this case, the third base station devices are the subjects that actually transmit the data signal. Hereinafter, a cell controlled by at least one third base station apparatus will be referred to as an active cell.

83When only the active cell transmits a data signal to the terminal device, the terminal device does not report the channel state and the measured channel state and precoding information for all cells belonging to the supercell, and measures only the active cell. And by performing the report, it is possible to reduce the computational amount and feedback overhead of the terminal device.

84In this case, the terminal device may measure the strength of a radio signal (eg, a reference signal) transmitted from the serving cell and neighbor cells of the serving cell and feed it back to the super node. The super node may select a cell that can be substantially helpful to the terminal device as an active cell based on information fed back from the terminal device, and transmit information about the selected active cell to the terminal device.

85For example, assuming that the supercell is configured as shown in FIG. 3, cell A 330 and cell C 350 may be selected as active cells for the terminal device 310. In this case, cell B 340 does not actually participate in the transmission of the data signal. In addition, since the terminal device 320 is located in the center portion of the supercell, all of the cell D360, the cell E370, and the cell F380 can be selected as an active cell for the terminal device 320. .

86When the channel environment around the terminal device is changed, the super node may change the active cell based on the measurement result of the radio signal strength fed back from the terminal device. In this case, the super node retransmits information about the changed active cell to the terminal device.

884 is a diagram illustrating the concept of uplink multi-cell cooperative communication involving three base station devices according to an embodiment of the present invention.

89In FIG. 4, the number of base station devices involved in uplink communication is limited to three (that is, the multi-cell cooperative communication system includes three base station devices), but the multi-cell cooperative communication system according to an embodiment of the present invention It can be said to those skilled in the art that it may include two or more base station devices.

90The terminal device 410 transmits a data signal to the base station device 420 of the serving cell, as well as the neighbor cell base station device 430 and the neighbor cell base station device 440 that are in charge of the neighbor cell adjacent to the serving cell. Hereinafter, a data signal received from the serving cell base station apparatus 420 will be referred to as a first data signal, and a data signal received from the neighbor cell base station apparatus 430 and the neighbor cell base station apparatus 440 will be referred to as a second data signal. .

91The neighbor cell base station device 430 and the neighbor cell base station device 440 that have received the second data signal may process the second data signal and transmit the processed second data signal to the serving cell base station device 420. In this case, the serving cell base station apparatus 410 may demodulate the first data from the first data signal using the processed second data signal. The processed second data signal may include at least one of second data included in the second data signal and information about the second data signal.

93Hereinafter, a method of transmitting the processed second data signal from a plurality of neighbor cell base station devices to a serving cell base station device will be described in detail.

95<u style="single">A. A method of transmitting a second data signal to a serving cell base station</u>

97According to an embodiment of the present invention, the neighbor cell base station device may transmit the received second data signal itself to the serving cell base station device. Further, according to another embodiment of the present invention, the neighbor cell base station apparatus may quantize the received second data signal and transmit it to the serving cell base station apparatus.

98In this case, the neighbor cell base station apparatus transmits information on the second data signal to the serving cell base station apparatus, and the information on the second data signal is the second data signal itself or the quantized second data signal.

99In addition, the neighbor cell base station apparatus can quantize all signals received from the terminal device as well as the second data signal and transmit it to the serving cell base station apparatus. As an example, the neighbor cell base station apparatus may quantize and transmit a signal carried on a subcarrier through which a reference signal is transmitted.

101<u style="single">B. A method of transmitting a soft decision value and an effective noise variance value for each of a plurality of second data symbols included in the second data signal to the serving cell base station</u>

103According to an embodiment of the present invention, the neighbor cell base station apparatus derives a softness determination value for each of the plurality of second data symbols included in the second data signal and an effective noise dispersion value for each of the plurality of second data symbols, , A ductility determination value and an effective noise dispersion value for each of the derived plurality of second data symbols may be transmitted to the serving cell base station apparatus.

104That is, the neighbor cell base station apparatus transmits information on the second data signal to the serving cell base station apparatus, and the information on the second data signal may be a softness determination value and an effective noise dispersion value for each of the plurality of second data symbols. .

105Here, each of the plurality of base station devices includes a symbol detector and a channel decoder, and the softness determination value and the effective variance value are values ​​that are the output of the symbol detector and the input of the channel decoder.

106The serving cell base station apparatus determines the softness determination value and the effective noise dispersion value for each of the plurality of first data symbols included in the first data signal based on the softness determination value and the effective noise dispersion value for each of the plurality of second data symbols. Can be derived.

107A more detailed description of an example of deriving a ductility determination value and an effective variance value in a plurality of base station devices is as follows. The example below assumes OFDM transmission.

108The number of second antennas (that is, transmit antennas) provided in the terminal device <img file="WO2010143780A2_D0022.tif" />,<sub />The number of data symbols transmitted per carrier in the terminal device <img file="WO2010143780A2_D0023.tif" />, The number of the first antenna (that is, the receiving antenna) provided in the base station device <img file="WO2010143780A2_D0024.tif" />, Vector a data symbol transmitted from the terminal device using the j-th carrier <img file="WO2010143780A2_D0025.tif" />, Vector the data signal received from the base station device <img file="WO2010143780A2_D0026.tif" />If you mark <img file="WO2010143780A2_D0027.tif" />Wow <img file="WO2010143780A2_D0028.tif" />The relationship between Equation 3 below is established.

109[Equation 3]

110<img file="WO2010143780A2_D0029.tif" />

111here, <img file="WO2010143780A2_D0030.tif" />Is the sum of AWGN (Additive White Gaussian Noise) noise and interference noise for each receive antenna of the j-th carrier. <img file="WO2010143780A2_D0031.tif" /> Is indicated by, <img file="WO2010143780A2_D0032.tif" />Is applied to the j-th carrier <img file="WO2010143780A2_D0033.tif" /> × <img file="WO2010143780A2_D0034.tif" />Means a precoding matrix having a size of <img file="WO2010143780A2_D0035.tif" /> The <img file="WO2010143780A2_D0036.tif" /> × <img file="WO2010143780A2_D0037.tif" />It means the channel matrix of the j-th carrier having the size of.

112Here, it is assumed that the average transmission power for each transmission antenna is normalized as in Equation 4 below.

113[Equation 4]

114<img file="WO2010143780A2_D0038.tif" />

115Here, E{} is effective power, superscript H is Hermitian Transpose, <img file="WO2010143780A2_D0039.tif" />The <img file="WO2010143780A2_D0040.tif" />It means each unit matrix having the size of.

116According to an embodiment of the present invention, the base station apparatus may detect a transmission signal of each antenna using a ZF (Zero-Forcing) detection method. In this case, the ductility determination value of the data symbol can be derived according to Equation 5 below.

117[Equation 5]

118<img file="WO2010143780A2_D0041.tif" />

119here, <img file="WO2010143780A2_D0042.tif" />Denotes the ductility determination value of the j-th data symbol according to the ZF detection method, and the superscript eff denotes an effective value.

120Also, the effective noise dispersion of the j-th carrier <img file="WO2010143780A2_D0043.tif" />(here, <img file="WO2010143780A2_D0044.tif" /> Is the i-th data symbol transmitted on the j-th carrier <img file="WO2010143780A2_D0045.tif" />Is the effective noise variance for ).

121[Equation 6]

122<img file="WO2010143780A2_D0046.tif" />

123According to another embodiment of the present invention, the base station apparatus may detect a transmission signal of each antenna using a MMSE (Minimum Mean Square Error) detection method. In this case, the ductility determination value of the data symbol can be derived according to Equation 7 below.

124[Equation 7]

125<img file="WO2010143780A2_D0047.tif" />

126here, <img file="WO2010143780A2_D0048.tif" />Denotes the ductility determination value of the j-th data symbol according to the MMSE detection method.

127Also, the effective noise dispersion of the j-th carrier can be derived from Equation 6 above.

129<u style="single">C. A method of transmitting a soft decision value and an average effective noise dispersion value for each of a plurality of second data symbols included in the second data signal to a serving cell base station</u>

131According to an embodiment of the present invention, the neighbor cell base station apparatus derives a ductility determination value and an effective noise dispersion value for each of a plurality of second data symbols included in the second data signal, and uses the derived effective noise dispersion value To derive an average effective noise variance value for all resource blocks allocated to the terminal device or resource blocks of a predetermined size, and serve a softness determination value and an average effective noise variance value for each of the plurality of derived second data symbols It can be transmitted to a cell base station device.

132That is, the neighbor cell base station apparatus transmits information on the second data signal to the serving cell base station apparatus, and the information on the second data signal may be a softness determination value and an average effective noise dispersion value for each of the plurality of second data symbols. have.

133In this case, the average effective noise dispersion value derived for each section is transmitted to the serving cell base station device, not the individual effective noise dispersion value, so that the amount of data transmitted can be reduced.

134An example of deriving an average effective noise variance value from a neighbor cell base station device will be described in detail.

135First, assuming that there are a total of M carriers in a resource block to be averaged, an effective noise dispersion value <img file="WO2010143780A2_D0049.tif" />Mean value of <img file="WO2010143780A2_D0050.tif" />Can be derived as in Equation 8 below.

136[Equation 8]

137<img file="WO2010143780A2_D0051.tif" />

138Where the average value <img file="WO2010143780A2_D0052.tif" />This effective noise variance value <img file="WO2010143780A2_D0053.tif" />In order to represent the representative of the well, it is preferable that carriers located in a resource block taking an average are located adjacent to each other in the frequency space and the same precoding is applied. I.e. for all j<img file="WO2010143780A2_D0054.tif" />It is desirable to establish a relationship. This is due to the fact that when different precodings are applied, the effective noise variance value is highly likely to be different for each carrier.

140<u style="single">D. A method of transmitting a softness determination value for each of a plurality of second data bits included in the second data signal to a serving cell base station</u>

142According to an embodiment of the present invention, the neighbor cell base station apparatus derives a softness determination value for each of the plurality of second data bits included in the second data signal, and determines the softness for each of the plurality of derived second data bits. The value can be transmitted to the serving cell base station device.

143That is, the neighbor cell base station apparatus transmits information on the second data signal to the serving cell base station apparatus, and the information on the second data signal may be a softness determination value for each of the plurality of second data bits.

144Here, the ductility determination value for each of the plurality of second data bits means a log likelihood ratio (LRR) in bit units obtained after passing through a symbol detector. That is, when the LLR of the second data bit b is indicated as LLR(b), the LLR(b) has the probability that the second data bit b is "1" (p(b=1)) and the probability that it is "0" (p (b=0)) is the natural logarithm of the ratio. This can be expressed as Equation (9).

145[Equation 9]

146<img file="WO2010143780A2_D0055.tif" />

147Here, the LLR for each second data bit transmitted to the serving cell base station apparatus may be an input value of a channel decoder or an output value generated as a decoding result.

149<u style="single">E. A method of transmitting the demodulated second data from the second data signal to the serving cell base station</u>

151According to an embodiment of the present invention, the neighbor cell base station device may demodulate the second data by performing symbol detection, decoding, etc. on the second data signal, and transmit the demodulated second data to the serving cell base station device.

152That is, the neighbor cell base station apparatus can transmit the second data itself to the serving cell base station apparatus.

153In this case, the neighbor cell base station apparatus can transmit the demodulated second data only when demodulation of the second data is successfully performed.

155<u style="single">F. Other</u>

157According to an embodiment of the present invention, the neighbor cell base station apparatus is a second cell signal generated from the method of A to E only when receiving a request for the transmission of the information or the second data signal from the base station device The information on the 2 data signal or the second data may be transmitted to the serving cell base station apparatus.

158In addition, according to an embodiment of the present invention, when the demodulation of the second data is successfully performed, the neighbor cell base station apparatus transmits the demodulated second data to the serving cell base station apparatus, and the demodulation of the second data is successful. If not performed, information on the second data signal generated according to the above A to D method may be transmitted to the serving cell base station apparatus.

159In addition, according to an embodiment of the present invention, the neighbor cell base station apparatus may transmit only information on whether or not demodulation success/failure of whether demodulation of the second data was successfully performed to the serving cell base station apparatus.

160In this case, the serving cell base station apparatus may transmit a request for transmission of information about the second data signal or second data to the neighboring cell base station apparatus based on the information on whether demodulation is successful/failure. When the demodulation of the second data is not successfully performed, the neighbor cell base station apparatus that has received the transmission request transmits information on the second data signal generated according to the methods A to D to the serving cell base station apparatus, If demodulation of the second data is not successfully performed, the second data generated according to the E method can be transmitted to the serving cell base station apparatus.

162Hereinafter, a terminal device performing cooperative communication with a plurality of base station devices will be described in detail with reference to FIG. 5.

1635 is a block diagram showing a detailed configuration of a terminal device 500 according to an embodiment of the present invention.

164The terminal device 500 according to an embodiment of the present invention includes a storage unit 510, a reception unit 520, a channel estimation unit 530, a selection unit 540, and a transmission unit 550. Hereinafter, the function of each component will be described in detail.

165The storage unit 510 stores a codebook including at least one precoding matrix composed of a plurality of precoding vectors. The codebook stored in the storage unit 510 is the same codebook as the codebook stored in the plurality of base station devices.

166The receiver 520 receives radio signals from a plurality of base station devices. For example, the wireless signal may be either a reference signal or a data signal.

167The channel estimator 530 estimates states of a plurality of channels formed between the plurality of base station devices and the terminal device 500 based on the received radio signal.

168The selector 540 selects any one precoding matrix from at least one precoding matrix included in the codebook based on the estimated state of the plurality of channels, and a plurality of precodings constituting the selected one precoding matrix. At least one precoding vector is selected from the vectors.

169The transmission unit 550 may transmit a second feedback signal including information on the selected at least one precoding vector to at least one base station device among the plurality of base station devices.

170According to an embodiment of the present invention, the selector 540 precodes any one of the at least one precoding matrix for predetermined specific resource blocks or based on resource blocks preferred by the terminal device 500. The matrix may be selected and at least one preferred precoding vector may be selected from among a plurality of precoding vectors included in the selected one precoding matrix.

171The size of the resource blocks targeted by the selected precoding matrix and the precoding vector may be previously specified in various sizes.

172According to an embodiment of the present invention, in order to reduce the amount of information of the second feedback signal transmitted through the transmission unit 550, the selection unit 540 is preferred for the predetermined specific resource blocks or the terminal device 500 Preferred precoding matrix and precoding vector may be selected by assuming that the same precoding matrix and precoding vector are applied to the resource blocks.

173According to another embodiment of the present invention, the selector 540 may select a preferred precoding matrix and a precoding vector for each individual resource block.

174In addition, according to an embodiment of the present invention, the terminal device 500 may include an intensity measurement unit (not shown) for measuring the intensity of a plurality of wireless signals. In this case, the transmission unit 550 may transmit a first feedback signal including the strengths of the measured plurality of wireless signals.

175As mentioned above, the first feedback signal can be used to select at least one second base station device that is responsible for the supercell.

176The super node (that is, the first base station device) selects at least one second base station device that controls the supercell based on the first feedback signal, and only at least one second base station device transmits a data signal to the terminal device 500 When it is controlled to transmit, the receiving unit 510 receives information on at least one second base station device from the super node, and only receives radio signals transmitted from the at least one second base station device based on the received information. can do.

177As described above, the present invention has been described by specific matters such as specific components, etc. and limited embodiments and drawings, but is provided to help the overall understanding of the present invention, and the present invention is not limited to the above embodiments , Anyone who has ordinary knowledge in the field to which the present invention pertains can make various modifications and variations from these descriptions. Accordingly, the spirit of the present invention should not be limited to the described embodiments, and should not be determined, but all claims that are equivalent or equivalent to the scope of the claims as well as the claims below will be considered to belong to the scope of the spirit of the invention. .