JP6053159B2 - Wireless communication system, distributed station apparatus, and communication method - Google Patents

Description

  The present invention physically extends a plurality of antenna units equipped with a part of the base station function, a distributed station device used as a distributed station, a wireless communication system including a plurality of distributed stations and a central station that controls them, and The present invention relates to a communication method of a distributed station.

  In a wireless communication system, particularly a mobile communication system, a configuration in which a plurality of antenna units equipped with a part of a base station function are physically extended and used as a distributed station is being studied. Here, the antenna unit refers to a unit equipped with a transmission interface, a radio transceiver, and an antenna. The base station that overhangs the distributed station has a function of controlling a plurality of distributed stations as a central station. In a communication system for performing communication between the central station and the distributed station, two system configurations in which the functional distribution of the central station and the distributed station are different are being studied.

  One is called Full Centralization, and as shown in FIG. 1, a central station 91 is equipped with a physical layer function excluding an antenna unit and functions higher than the data link layer, and a distributed station 92 with only the antenna unit is extended. System configuration. The other is called Partial Centralization, and has a system configuration in which a central station 91 is equipped with functions higher than the data link layer as shown in FIG. 2, and a distributed station 92 equipped with a physical layer function including an antenna unit is extended. (For example, refer nonpatent literature 1.).

  In the full centralization, the physical layer is controlled in the central station 91 as shown in FIG. 1, whereas in the central centralization, the central station 91 and the distributed station 92 exchange the physical layer control information as shown in FIG. There is a need. At present, the system configuration that is used more frequently is Full Centralization, and a communication system between the central station 91 and the distributed station 92 in this configuration is CPRI (Common Public Radio Interface) (see, for example, Non-Patent Document 2). The one using digital RoF (Radio over Fiber) technology represented by

  On the other hand, an area covered by one base station 94 in a mobile communication system is called a cell, and a radio signal transmitted from a desired base station 94 when a terminal 95 serving as a mobile station reaches the end region of the cell. There is a problem that the transmission speed between the base station 94 and the terminal 95 which is a mobile station is remarkably reduced due to interference between the radio signal transmitted from the adjacent base station and the mobile station 95. As means for solving such a problem of signal interference between cells, as shown in FIGS. 3 and 4, adjacent base stations 94 (FIG. 3) or a central station 91 and a distributed station 92 or distributed stations 92 (FIG. 4). CoMP (Coordinated Multi-Point transmission / reception) technology (for example, refer to Non-Patent Document 3) that performs communication in cooperation with each other with respect to the terminal 95 that is a mobile station located at the cell edge. As one of the techniques for realizing CoMP in the downlink, there is JT (Joint Transmission) in which signals are transmitted from different base stations 94 or central stations 91 and distributed stations 92 or different distributed stations 92 at the same time and frequency. Among these, a method of performing transmission after performing precoding processing on signals transmitted from different cells in advance is called coherent JT.

China Mobile Research Institute, “C-RAN The Road Towns Green RAN,” Oct. , 2011, http: // labs. chinamobile. com / cran / CPRI, “CPRI Specification V5.0,” Sep. , 2011, http: // www. cpri. info / spec. html IEEE Communications Magazine, Vol. 50, no. 11 p. 44-50 “Coordinated Multipoint Transmission and Reception in LTE-Advanced Systems.”

  FIG. 5 shows a signal transmission flow when CoMP using coherent JT is performed in the system configuration of Full Centralization. In FIG. 5, the number of cooperating distributed stations is two, and one antenna is provided for each of the two decentralized stations. However, the number of cooperating distributed stations is not limited to two. A plurality of antennas may be provided.

The MAC function 11 of the data link layer performs DCI (Downlink Control Information) such as a transport block size, a modulation / coding scheme, and a precoding matrix in the physical layer based on CSI (Channel State Information) feedback from an uplink signal. The predetermined transport blocks d ₁ and d ₂ are transferred to the physical layer corresponding to each distributed station. Thereafter, the modulator 12 generates modulation symbols s ₁ and s ₂ to be transmitted to the respective distributed stations 92. Here, physical layer processing such as CRC (Cyclic Redundancy Check) assignment and encoding performed before and after modulation is omitted.

ここでｗｉｊはプリコーディング行列の各要素を表す。 The precoding unit 13 reads a precoding matrix determined by the MAC function 11 using the generated modulation symbol from a pre-defined codebook and performs precoding matrix calculation. The precoding matrix calculation outputs s _v1 and s _v2 are expressed by the following equation (1).

Here, wij represents each element of the precoding matrix.

The output s _v1 and s _v2 are transmitted to the distributed station 92 after the signal conversion unit 14 performs signal conversion for transmission to the distributed station. In the distributed station 92, the signal conversion unit 22 performs signal conversion on the transmitted signal, and the D / A conversion unit 23 performs D / A conversion to return the received signal to an analog signal. Then, it transmits from the antenna 21 as _sv1AN and _sv2AN . Here, before signal conversion in the signal conversion unit 14 of the central office 91, signal processing for performing multicarrier transmission such as OFDM (Orthogonal Frequency Division Multiplexing) is performed on _sv1AN and _sv2AN . There is also.

The same applies to the transport blocks following the transport blocks d ₁ and d ₂ and the modulation symbols corresponding to them. However, in the signal transmission in such a system configuration of the full centralization, a signal obtained by sampling and quantizing the modulation symbols s _v1 and s _v2 is transmitted, so that the transmission capacity between the central station 91 and the distributed station 92 is transmitted. There is a problem that becomes very large. For example, when CPRI is used for signal transmission, when wireless communication is performed at a downlink 75 Mbps transmission rate, the required transmission rate between the central station and the distributed station is approximately 12 times 1228 Mbps.

  On the other hand, in the case of performing CoMP using JT in the system configuration of Partial Centralization that can reduce the transmission capacity required between the central station 91 and the distributed station 92 compared to the system configuration of Full Centralization. Signal transmission is shown in FIG. Similarly to FIG. 5, the number of distributed stations linked in FIG. 6 need not be limited to two, and a single distributed station may have a plurality of antennas.

In the full centralization, the modulation performed in the central station 91 is performed in each distributed station 92. Here, similarly to Full Centralization, physical layer processing such as CRC assignment and encoding performed before and after modulation is omitted. Unlike Full Centralization, data transmitted between the central station 91 and the distributed station 92 is a DCI that controls the data stream of the transport blocks d ₁ and d ₂ and the physical layer functions before the physical layer processing is performed. Become. The data stream transmitted between the central station 91 and the distributed station 92 is not the data of the signal obtained by sampling and quantizing the radio signal, but the data of the transport blocks d ₁ and d _2. Since the increase in transmission capacity due to DCI is negligibly small for the reduction effect, the transmission capacity between the central station 91 and the distributed station 92 is significantly smaller than in the case of the full centralization. However, in Partial Centralization, since the physical layer functions are distributed, there is a problem in that precoding matrix operations performed using both modulation symbols s ₁ and s ₂ cannot be performed.

  An object of the present invention is to provide a distributed station apparatus capable of performing a precoding matrix operation even when physical layer functions are distributed in a system configuration of Partial Centralization, a wireless communication system including the same, and a communication method of the distributed station apparatus. To do.

  In the present invention, in the system configuration of Partial Centralization, data of modulation symbols necessary for the result of precoding matrix calculation between the central station and the distributed station, and the modulation scheme information corresponding thereto and the code corresponding to the precoding matrix used for the calculation By sending the DCI including the book number and the like, the precoding matrix operation can be performed even if the functions of the physical layer are distributed.

The distributed station apparatus according to the present invention is
A distributed station apparatus that includes one or more antennas that wirelessly communicate a data stream with a mobile terminal and wirelessly communicates the data stream with the mobile terminal according to control information transmitted from a central station apparatus that controls the one or more distributed station apparatuses. And
A number of data streams equal to or less than the total number of antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data stream with each mobile terminal, A receiving unit for receiving from the station device;
A modulator that modulates each data stream received from the central station device to generate modulation symbols for each data stream;
Select a predetermined matrix based on the control information, perform a matrix operation using the selected matrix and the modulation symbol, and select based on the control information in the data stream received from the central station device A computing unit that retrieves a specific data stream that is different for each distributed station ;
Is provided.

  The distributed station apparatus according to the present invention may further include a buffer for accumulating data streams received from the central station apparatus, and the modulator may read and modulate each data stream from the buffer.

Distributed station equipment according to the present invention,
A distributed station apparatus that includes one or more antennas that wirelessly communicate a data stream with a mobile terminal and wirelessly communicates the data stream with the mobile terminal according to control information transmitted from a central station apparatus that controls the one or more distributed station apparatuses. And
A number of data streams equal to or less than the total number of antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data stream with each mobile terminal, A receiving unit for receiving from the station device;
A modulator that modulates each data stream received from the central station device to generate modulation symbols for each data stream;
An element used for selecting a predetermined matrix based on the control information and extracting a data stream to be wirelessly communicated using an antenna provided in the distributed station apparatus among elements constituting the predetermined matrix. , taken out based on the control information, a calculation section that the extraction elements have a row matrix operation using the modulation symbols, retrieve the particular data stream of the data stream received from the central station,
Is provided.

  A radio communication system according to the present invention includes the distributed station apparatus according to the present invention, and a central station apparatus that transmits the control information and the data stream to the distributed station apparatus.

A wireless communication method for a distributed station apparatus according to the present invention includes:
A distributed station apparatus including one or more antennas that wirelessly communicate data streams with a mobile terminal performs wireless communication of data streams with the mobile terminal according to control information transmitted from a central station apparatus that controls the one or more distributed station apparatuses. A wireless communication method for a station device,
A number of data streams equal to or less than the total number of antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data stream with each mobile terminal, A receiving procedure for receiving from the station device;
A modulation procedure for modulating each data stream received from the central station apparatus to generate a modulation symbol for each data stream;
Select a predetermined matrix based on the control information, perform a matrix operation using the selected matrix and the modulation symbol, and select based on the control information in the data stream received from the central station device A calculation procedure for retrieving a specific data stream that is different for each distributed station ;
A transmission procedure for transmitting the data stream extracted in the calculation procedure to the mobile terminal;
In order.

  In the wireless communication method of the distributed station apparatus according to the present invention, in the reception procedure, the data stream received from the central station apparatus is accumulated in a buffer, and in the modulation procedure, each data stream is read from the buffer and modulated. Also good.

Wireless communication how a distributed station apparatus according to the present invention,
A distributed station apparatus including one or more antennas that wirelessly communicate data streams with a mobile terminal performs wireless communication of data streams with the mobile terminal according to control information transmitted from a central station apparatus that controls the one or more distributed station apparatuses. A wireless communication method for a station device,
A number of data streams equal to or less than the total number of antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data stream with each mobile terminal, A receiving procedure for receiving from the station device;
A modulation procedure for modulating each data stream received from the central station apparatus to generate a modulation symbol for each data stream;
An element used for selecting a predetermined matrix based on the control information and extracting a data stream to be wirelessly communicated using an antenna provided in the distributed station apparatus among elements constituting the predetermined matrix. , taken out based on the control information, a calculation procedure with the extraction elements have a row matrix operation using the modulation symbols, retrieve the particular data stream of the data stream received from the central station,
A transmission procedure for transmitting the data stream extracted in the calculation procedure to the mobile terminal;
In order .

  According to the present invention, there is provided a distributed station apparatus capable of performing precoding matrix calculation even when physical layer functions are distributed, a wireless communication system including the same, and a communication method of the distributed station apparatus in a system configuration of Partial Centralization. be able to.

An example of the system configuration of Full Centralization is shown. An example of the system configuration of Partial Centralization is shown. The schematic diagram of the 1st example of CoMP is shown. The schematic diagram of the 2nd example of CoMP is shown. An example of CoMP signal transmission in Full Centralization is shown. An example of CoMP signal transmission in Partial Centralization is shown. 1 shows an example of a wireless communication system configuration according to a first embodiment. 4 shows an exemplary configuration of a wireless communication system according to a second embodiment. 7 shows an example of a configuration of a wireless communication system according to a third embodiment. 10 shows an example of a wireless communication system configuration according to a fourth embodiment. 10 illustrates an example of a wireless communication system configuration according to a fifth embodiment.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
FIG. 7 shows an example of a wireless communication system according to this embodiment. The wireless communication system according to the present embodiment is a system using a system configuration of Partial Centralization, and includes a central station 91 that functions as a central station device, and distributed stations 92-1 and 92-2 that function as distributed station devices. Prepare. In the first embodiment, when the number of cooperating distributed stations is 2, and the number of antennas provided in each distributed station is 1, different data streams are transmitted from each distributed station 92. However, the number of cooperating distributed stations is not limited to two, and a single distributed station 92 may have a plurality of antennas. FIG. 7 shows CoMP signal transmission in Partial Centralization to which Embodiment 1 is applied. In FIG. 7 and subsequent figures, arrows indicating physical layer control by DCI are omitted.

  The central office 91 includes a MAC function unit 11 and a signal conversion unit 14. The signal converter 14 is provided for each distributed station 92. The distributed stations 92-1 and 92-2 include a signal conversion unit 22 that functions as a reception unit, a separation unit 25, a modulator 24, a precoding calculation unit 26 that functions as a calculation unit, and a D / A conversion unit 23. Is provided.

  The distributed stations 92-1 and 92-2 execute the wireless communication method of the distributed station apparatus according to the present embodiment. In the wireless communication method of the distributed station apparatus according to the present embodiment, a central station 91 in which a distributed station 92 including one or more antennas that wirelessly communicate data streams with a terminal 95 that is a mobile terminal controls the one or more distributed stations 92. Is a wireless communication method of the distributed station 92 that wirelessly communicates a data stream with the terminal 95 in accordance with the control information transmitted from, and includes a reception procedure, a modulation procedure, a calculation procedure, and a transmission procedure in this order.

In the reception procedure, the central station 91 transmits both transport blocks d ₁ and d ₂ corresponding to the modulation symbols s ₁ and s ₂ to the respective distributed stations 92-1 and 92-2, and further transmits DCI related thereto. To do. Then, the signal converter 22 receives the data stream and the control information from the central office 91. The control information is, for example, DCI. The data streams are the number of data streams equal to or less than the total number of antennas provided in all the distributed stations 92 to be controlled by the central station 91. In this embodiment, since the number of antennas is 2, the transport blocks d ₁ and d ₂ are received as two data streams.

In the modulation procedure, each of the distributed stations 92-1 and 92-2 separates d ₁ and d ₂ by the separation unit 25 such as a switch, and modulates the transport blocks d ₁ and d ₂ by the modulator 24. , Modulation symbols s ₁ and s ₂ are obtained. For this reason, the distributed stations 92-1 and 92-2 of this embodiment include the number of modulators 24 equal to the number of data streams. Here, physical layer processing such as CRC addition and encoding may be performed before and after modulation.

  Thereafter, the calculation procedure is executed. In the calculation procedure, the precoding calculation unit 26 extracts a data stream transmitted from each distributed station 92. At this time, the precoding operation unit 26 extracts a selected matrix from information on a predetermined matrix, and extracts it by performing a matrix operation using the selected matrix and a modulation symbol. The predetermined matrix is W. The matrix is selected based on the codebook and DCI.

The precoding matrix corresponding to the codebook number read from the transmitted DCI is referred to in the codebook, the matrix represented by the following equation (2) is extracted, and the precoding matrix operation represented by equation (1) is performed. This is performed by the precoding operation unit 26 of each distributed station 92.

Each of the distributed stations 92-1 and 92-2 executes a transmission procedure. In the transmission procedure, the antenna transmits the data stream extracted in the calculation procedure to the terminal 95.
The precoding operation unit 26 of the distributed station 92-1 discards s _v2 while leaving s _v1 according to DCI, while the precoding operation unit 26 of the distributed station 92-2 leaves s _v2 according to DCI and discards s _v1 . . Thereafter, D / A conversion is performed on each of the s _v1 and s _v2 in each of the distributed stations 92-1 and 92-2, and transmitted from the antenna as s _v1AN and _sv2AN . Here, before D / A conversion, signal processing for performing multicarrier transmission such as OFDM may be performed on s _v1 and s _v2 .

Compared to the CoMP signal transmission in the full centralization shown in FIG. 5, in the configuration of the first embodiment shown in FIG. 7, the signal transmitted between the central station 91 and the distributed station 92 is sampled and quantized with respect to the radio signal. Therefore, the transmission capacity between the central station 91 and the distributed station 92 is small because the increase in the transmission capacity due to the DCI is negligible for the effect of reducing the transmission capacity. Get smaller. Further, even in the case of CoMP signal transmission in FIG. 7, similarly to FIG. 5, analog signals s _v1AN , generated from modulation symbols s _v1 and s _v2 that have been subjected to precoding calculation processing at the antenna output of each distributed station 92. It can be seen that _sv2AN is obtained.

  As described above, the distributed station 92 and the wireless communication system including the distributed station 92 according to the present embodiment provide the data stream and the control information from the central station 91 to the distributed station 92 in the system configuration of Partial Centralization. The control information includes modulation scheme information and DCI such as a codebook number corresponding to a precoding matrix used for calculation. As a result, the distributed station 92 and the wireless communication system including the distributed station 92 according to the present embodiment can significantly reduce the transmission capacity because each distributed station 92 can perform a precoding matrix operation, and further uses coherent JT. CoMP can also be performed.

The same applies to the transport blocks following d ₁ and d ₂ and the modulation symbols corresponding to them. Note that it is not necessary to transmit all the transport block and DCI addressed to the distributed station 92-2 to the distributed station 92-1, and only the transport block and DCI addressed to the distributed station 92-2 involved in CoMP are transmitted to the distributed station 92-. 1 may be transmitted. The same applies to the reverse case.

  An existing interface may be used for signal conversion used for signal transmission between the central station 91 and the distributed station 92, or an original interface may be used. Also, the transport block and DCI may be divided in the time domain, or the transport block and DCI may be sent in packets and the DCI may be incorporated in the header. Also, physical layer processing such as CRC addition and encoding may be performed before and after modulation. Further, before D / A conversion, signal processing for performing multicarrier transmission such as OFDM may be performed. Further, by applying a PON (Passive Optical Network) technique to the central station 91 and the distributed station 92, data can be efficiently transmitted to each distributed station 92 using the multicast function of the PON.

(Embodiment 2)
Unlike the first embodiment, the same data stream may be transmitted from the distributed station 92 as in the second embodiment. FIG. 8 shows CoMP signal transmission when the same data stream is sent from each distributed station 92 in the first embodiment.

その後、各分散局９２−１及び９２−２においてｓ_ｖ１，ｓ_ｖ１’それぞれに対して、Ｄ／Ａ変換が行われ、ｓ_ｖ１ＡＮ，ｓ_ｖ１ＡＮ’としてアンテナから送信される。これにより、ある端末９５に対して同一のデータストリームを、信頼性を高めて送信することができる。 First, the central station 91 transmits the transport block d ₁ corresponding to the modulation symbol s ₁ and the DCI related thereto to each of the distributed stations 92-1 and 92-2. It modulates the transport block _{d 1} in the modulator 24 of the respective distribution stations 92-1 and 92-2, to obtain the modulation symbol _{s 1.} Thereafter, the precoding operation unit 26 of each of the distributed stations 92-1 and 92-2 refers to the precoding matrix corresponding to the codebook number read from the transmitted DCI in the codebook, and the following equation ( The matrix shown in 3) (in this case, a vector) is taken out, and a precoding matrix calculation expressed by the following equation (4) is performed. Leaving _{s v1} 'discards, whereas _{s v1} according DCI In the pre-encoding calculating unit 26 of the distributed stations 92-2' _{s v1} according DCI In the pre-encoding calculating unit 26 of the distributed stations 92-1 to _{s v1} leaving Discard.

Thereafter, D / A conversion is performed on each of the s _v1 and s _v1 ′ in each of the distributed stations 92-1 and 92-2, and is transmitted from the antenna as s _v1AN and s _v1AN ′. Thereby, the same data stream can be transmitted to a certain terminal 95 with improved reliability.

  An existing interface may be used for signal conversion used for signal transmission between the central station 91 and the distributed station 92, or an original interface may be used. Also, the transport block and DCI may be divided in the time domain, or the transport block and DCI may be sent in packets and the DCI may be incorporated in the header. Also, physical layer processing such as CRC addition and encoding may be performed before and after modulation. Further, before D / A conversion, signal processing for performing multicarrier transmission such as OFDM may be performed. Further, the PON technology can be applied to the central station and the distributed station 92, and data can be efficiently transmitted to each distributed station 92 by using the multicast function of the PON.

(Embodiment 3)
Unlike the first embodiment, as in the third embodiment, the number of the modulators 24 may be reduced by using the buffer 27 in each distributed station 92. FIG. 9 shows CoMP signal transmission when the number of the modulators 24 is reduced by using the buffer 27 in each distributed station 92 in the first embodiment. The modulation symbols s ₁ and s ₂ are obtained by the _single modulator 24 using the buffer 27 for the transport blocks d ₁ and d ₂ reaching the respective distributed stations 92-1 and 92-2. Thereafter, the modulation symbols s ₁ and s ₂ are separated using the separation unit 25, and the precoding operation unit 26 performs the precoding matrix operation in the same manner as in the first embodiment, and the s _v1AN , s It is transmitted from the antenna as _v2AN . Here, it is not necessary to limit the number of processing such as encoding and the number of modulators 24 to one as shown in FIG. 9, and there may be a plurality of systems. In that case, the separation unit 25 is also required after the buffer 27.

  An existing interface may be used for signal conversion used for signal transmission between the central station 91 and the distributed station 92, or an original interface may be used. Also, the transport block and DCI may be divided in the time domain, or the transport block and DCI may be sent in packets and the DCI may be incorporated in the header. Also, physical layer processing such as CRC addition and encoding may be performed before and after modulation. Further, before D / A conversion, signal processing for performing multicarrier transmission such as OFDM may be performed. Further, the PON technology can be applied to the central station and the distributed station 92, and data can be efficiently transmitted to each distributed station 92 by using the multicast function of the PON.

(Embodiment 4)
Unlike Embodiment 1, like Embodiment 4, it is the element required for a matrix calculation result instead of taking out a precoding matrix from the codebook referred by the precoding calculating part 26 of each distributed station 92-1 and 92-2. It is also possible to perform the calculation by taking out only. FIG. 10 shows CoMP signal transmission in the case where only elements necessary for matrix operation are extracted from the codebook referred to by each of the distributed stations 92-1 and 92-2 in the first embodiment.

の演算に必要なｗ_１１，ｗ_１２のみを取り出し、分散局９２−２では次の式（６）で表されるｓ_ｖ２、

の演算に必要なｗ_２１，ｗ_２２のみを取り出し、それぞれの演算を行う。その後、各分散局９２−１及び９２−２においてｓ_ｖ１，ｓ_ｖ２それぞれに対してＤ／Ａ変換が行われ、ｓ_ｖ１ＡＮ，ｓ_ｖ２ＡＮとしてアンテナから送信される。 Similar to the first embodiment, after obtaining the modulation symbols s ₁ and s ₂ at the respective distributed stations 92-1 and 92-2, the precoding matrix corresponding to the codebook number read from the transmitted DCI is referred to by the codebook. Then, only elements necessary for each distributed station 92 are extracted from the precoding matrix calculation results shown by the equation (1). That is, in the distributed station 92-1, s _{v1 represented} by the following equation (5),

_{W 11,} required for the operation of _{w 12} extracting only, _{s v2} represented by the distributed station 92-2 in the following equation (6),

Only w ₂₁ and w ₂₂ necessary for the calculation are taken out and the respective calculations are performed. Thereafter, D / A conversion is performed on each of the s _v1 and s _v2 in each of the distributed stations 92-1 and 92-2, and transmitted from the antenna as s _v1AN and _sv2AN .

  An existing interface may be used for signal conversion used for signal transmission between the central station 91 and the distributed station 92, or an original interface may be used. Also, the transport block and DCI may be divided in the time domain, or the transport block and DCI may be sent in packets and the DCI may be incorporated in the header. Also, physical layer processing such as CRC addition and encoding may be performed before and after modulation. Further, before D / A conversion, signal processing for performing multicarrier transmission such as OFDM may be performed. Further, PON technology can be applied to the central station 91 and the distributed station 92, and data can be efficiently transmitted to each distributed station 92 using the multicast function of the PON.

(Embodiment 5)
Unlike the first embodiment, as in the fifth embodiment, the number of distributed stations may not be limited to two, and each distributed station 92 may have a plurality of antennas. When the number of distributed stations is 1, CoMP cannot be implemented, but MIMO (Multiple-Input Multiple-Output) transmission using precoding processing is possible in the distributed station 92 having a plurality of antennas.

Further, even when there are a plurality of distributed stations and each of the distributed stations 92 has a plurality of antennas, each distributed station 92 can perform MIMO transmission using precoding. FIG. 11 shows CoMP or MIMO signal transmission when the number of distributed stations and the number of antennas per distributed station 92 are generalized in the first embodiment. In FIG. 11, the number of distributed stations to be linked is L (L is a natural number of 1 or more), and the number of antennas provided in the distributed station 92-M (M = 1,..., L) is NM. The total number K of antennas provided in all the distributed stations 92 is expressed by the following equation (7).

Each distributed station 92 transmits K transport blocks from d ₁ to d _K and DCI related thereto. Each distributed stations 92, the K-number of the transport blocks from _{d 1} to a _{d K} were separated by the demultiplexer (DEMUX) 25, performs modulation by the modulator 24 in each, the K from _{s 1} to _{s K} Get the modulation symbols. Thereafter, the precoding matrix corresponding to the codebook number read from the transmitted DCI is referred to in the codebook, and a desired precoding matrix is extracted from the precoding matrix, and matrix calculation is performed.

At the output of the matrix operation of the distributed station 92-M, NM modulation symbols equal to the number of antennas provided in the distributed station 92 are obtained, and NM radio signals are transmitted from the antenna through D / A conversion. For example, N1 modulation symbols of _{s V1N1} is obtained from _{s v11} Distributed station 92-1. Then, OFDM signal generated for each, D / A conversion is _performed, and transmitted from the antenna as _{N 1} pieces of radio signals _{s V1N1AN} from _{s v11AN.}

Note that any or all of the methods shown in the second, third, and fourth embodiments may be applied to the fifth embodiment. For example, if the buffer 27 is used as in the third embodiment, the number of modulators 24 used to obtain K modulation symbols from s ₁ to s _K can be reduced to one at each distributed station 92.

  An existing interface may be used for signal conversion used for signal transmission between the central station 91 and the distributed station 92, or an original interface may be used. Also, the transport block and DCI may be divided in the time domain, or the transport block and DCI may be sent in packets and the DCI may be incorporated in the header. Also, physical layer processing such as CRC addition and encoding may be performed before and after modulation. Further, before D / A conversion, signal processing for performing multicarrier transmission such as OFDM may be performed. Further, PON technology can be applied to the central station 91 and the distributed station 92, and data can be efficiently transmitted to each distributed station 92 using the multicast function of the PON.

  The present invention can be applied to the information communication industry.

11: MAC function unit 12: modulator 13: precoding matrix calculation unit 14: signal conversion unit 21: antenna 22: signal conversion unit 23: D / A conversion unit 24: modulator 25: separation unit 26: precoding calculation unit 27: Buffer 91: Central station 92: Distributed station 93: Core network 94: Base station 95: Terminal

Claims (6)

A distributed station apparatus that includes one or more antennas that wirelessly communicate a data stream with a mobile terminal and wirelessly communicates the data stream with the mobile terminal according to control information transmitted from a central station apparatus that controls the one or more distributed station apparatuses. And
A number of data streams equal to or less than the total number of antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data stream with each mobile terminal, A receiving unit for receiving from the station device;
A modulator that modulates each data stream received from the central station device to generate modulation symbols for each data stream;
Select a predetermined matrix based on the control information, perform a matrix operation using the selected matrix and the modulation symbol, and select based on the control information in the data stream received from the central station device A computing unit that retrieves a specific data stream that is different for each distributed station ;
A distributed station apparatus comprising: A buffer for storing a data stream received from the central office device;
The modulator reads and modulates each data stream from the buffer;
The distributed station apparatus according to claim 1. A distributed station apparatus that includes one or more antennas that wirelessly communicate a data stream with a mobile terminal and wirelessly communicates the data stream with the mobile terminal according to control information transmitted from a central station apparatus that controls the one or more distributed station apparatuses. And
A number of data streams equal to or less than the total number of antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data stream with each mobile terminal, A receiving unit for receiving from the station device;
A modulator that modulates each data stream received from the central station device to generate modulation symbols for each data stream;
An element used for selecting a predetermined matrix based on the control information and extracting a data stream to be wirelessly communicated using an antenna provided in the distributed station apparatus among elements constituting the predetermined matrix. , taken out based on the control information, a calculation section that the extraction elements have a row matrix operation using the modulation symbols, retrieve the particular data stream of the data stream received from the central station,
A distributed station apparatus comprising: A distributed station apparatus including one or more antennas that wirelessly communicate data streams with a mobile terminal performs wireless communication of data streams with the mobile terminal according to control information transmitted from a central station apparatus that controls the one or more distributed station apparatuses. A wireless communication method for a station device,
A number of data streams equal to or less than the total number of antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data stream with each mobile terminal, A receiving procedure for receiving from the station device;
A modulation procedure for modulating each data stream received from the central station apparatus to generate a modulation symbol for each data stream;
Select a predetermined matrix based on the control information, perform a matrix operation using the selected matrix and the modulation symbol, and select based on the control information in the data stream received from the central station device A calculation procedure for retrieving a specific data stream that is different for each distributed station ;
A transmission procedure for transmitting the data stream extracted in the calculation procedure to the mobile terminal;
A wireless communication method for a distributed station apparatus having the following in order. In the reception procedure, the data stream received from the central station device is accumulated in a buffer,
In the modulation procedure, each data stream is read from the buffer and modulated.
The wireless communication method of the distributed station apparatus according to claim 4 . A distributed station apparatus including one or more antennas that wirelessly communicate data streams with a mobile terminal performs wireless communication of data streams with the mobile terminal according to control information transmitted from a central station apparatus that controls the one or more distributed station apparatuses. A wireless communication method for a station device,
A number of data streams equal to or less than the total number of antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data stream with each mobile terminal, A receiving procedure for receiving from the station device;
A modulation procedure for modulating each data stream received from the central station apparatus to generate a modulation symbol for each data stream;
An element used for selecting a predetermined matrix based on the control information and extracting a data stream to be wirelessly communicated using an antenna provided in the distributed station apparatus among elements constituting the predetermined matrix. , taken out based on the control information, a calculation procedure with the extraction elements have a row matrix operation using the modulation symbols, retrieve the particular data stream of the data stream received from the central station,
A transmission procedure for transmitting the data stream extracted in the calculation procedure to the mobile terminal;
A wireless communication method for a distributed station apparatus having the following in order.

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