JP6356572B2 - Wireless communication system, central station apparatus, distributed station apparatus, communication method for central station apparatus, and communication method for distributed station apparatus - Google Patents

Description

  The present invention relates to a wireless communication system in which a plurality of antenna units mounted with a part of a base station function are physically extended to use as a distributed station, a distributed station device, a central station device that controls a plurality of distributed station devices, a plurality of The present invention relates to a wireless communication system including a distributed station apparatus and a central station apparatus, a communication method for the central station apparatus, and a communication method for the distributed station apparatus.

  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 more widely used is Full Centralization, and the communication method between the central station 91 and the distributed station 92 in this configuration is described in CPRI (Common Public Radio Interface) (see, for example, Non-Patent Document 2). A representative one using digital RoF (Radio over Fiber) technology is used.

  On the other hand, in a mobile communication system, an area covered by one base station 94 connected to the core network 93 is called a cell, and when a terminal 95 as a mobile station reaches the end region of the cell, a desired The problem is that the radio signal transmitted from the base station 94 interferes with the radio signal transmitted from the adjacent base station, and the transmission speed between the base station 94 and the mobile station terminal 95 is significantly reduced. It has become. As a means for solving such a problem of signal interference between cells, as shown in FIG. 3 and FIG. 4, each adjacent base station 94 connected to the core network 93 (FIG. 3) or connected to the core network 93. CoMP (Coordinated Multi-Point transmission / reception) technology in which the central station 91 and the distributed station 92 or between the distributed stations 92 (FIG. 4) communicate with each other with respect to the terminal 95 which is a mobile station located at the cell edge. (See, for example, Non-Patent Document 3). 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.

“C-RAN The Road Towns Green RAN”, [online], December 2013, China Mobile Research Institute, [October 01, 2014 search], Internet <http: // labs. chinamobile. com / cran / wp-content / uploads / 2014/06 / 20140613-C-RAN-WP-3.0. pdf> “CPRI Specification V6.0”, [online], August 2013, CPRI, [October 1, 2014 search], Internet <http: // www. cpri. info / downloads / CPRI_v — 6 — 0 — 2013-08-30. pdf> Hidekazu Taoka, 5 others, "MIMO and inter-cell cooperative transmission / reception technology in LTE-Advanced", NTT DOCOMO Technical Journal, NTT DoCoMo, Inc., Vol. 18, no. 2, pp. 22-30

  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 the distributed stations 92 to be linked is two, and one antenna 21 is provided for each of the two distributed stations 92. However, the number of the distributed stations 92 to be linked is not limited to two. There may be a plurality of antennas provided in one distribution station 92.

The data link layer MAC (Media Access Control) function unit 11 uses DCI (Channel State Information) feedback from the uplink signal to indicate information such as the transport block size and modulation / coding scheme in the physical layer. (Downlink Control Information) is determined, and predetermined transport blocks d1 and d2 are generated. The MAC function unit 11 inputs the transport blocks d1 and d2 to the modulator 12. Thereafter, the modulator 12 generates a modulation symbol s1 and s2 are transmitted from the transport block _{d 1} and _{d 2} in the dispersion station 92. Here, physical layer processing such as CRC (Cyclic Redundancy Check) assignment and encoding performed before and after modulation is omitted.

Thereafter, the precoding matrix calculation unit 13 performs precoding matrix calculation using the generated modulation symbols s1 and s2 and the precoding matrix w generated and notified by the MAC function unit 11. The outputs s _1p and s _2p of the precoding matrix calculation unit 13 are expressed by the following equation (1).

ここでｗ_ｉｊ（ｉ＝１，２ ｊ＝１，２） はプリコーディング行列の各要素を表す。

Here, w _ij (i = 1, 2 j = 1, 2) represents each element of the precoding matrix.

The output s _1p and s _2p are transmitted to the distributed stations 92-1 and 92-2 after the signal conversion unit 14 performs signal conversion for transmission to the distributed station 92, respectively. The distributed stations 92-1 and 92-2 perform signal conversion on the signal transmitted by the signal conversion unit 22, and perform D / A conversion to return the signal received by the D / A conversion unit 23 to an analog signal. Then, it transmits from the antenna 21 as _s1AN and _s2AN . 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 s _1p and s _2p . There is also.

The same applies to the transport blocks following 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 Full Centralization, a signal obtained by sampling and quantizing the pre-coded modulation symbols s _1p and s _2p is transmitted. There is a problem that the transmission capacity between them becomes very large. For example, when CPRI is used for signal transmission, when wireless communication is performed at a transmission rate of 75 Mbps downstream, the transmission rate required between the central station 91 and the distributed station 92 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 92 linked in FIG. 6 is not limited to two, and the number of antennas 21 provided in one distributed station 92 may be plural.

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 includes data d ₁ and d ₂ of the transport block before the physical layer processing is performed, and DCI that controls the function of the physical layer. Become.

The data transmitted between the central station 91 and the distributed station 92 is not the data of the signal sampled and quantized with respect to the radio signal but the data d ₁ and d ₂ of the transport block. Since the increase in transmission capacity due to DCI is negligibly small with respect to the reduction effect, the transmission capacity between the central station 91 and the distributed station 92 is significantly smaller than that in the case of the full centralization. However, since the physical layer functions are distributed in Partial Centralization, there is a problem in that precoding matrix operations performed using both modulation symbols s ₁ and s ₂ cannot be performed.

  In order to solve the above-described problems, the present invention provides a wireless communication system, a central station apparatus, a distributed station apparatus, and a central station capable of performing a precoding matrix operation even when physical layer functions are distributed in a system configuration of Partial Centralization. It is an object of the present invention to provide an apparatus communication method and a distributed station apparatus communication method.

  In order to achieve the above object, in the present invention, in the system configuration of Partial Centralization, in addition to modulation symbol data necessary for precoding matrix calculation and corresponding DCI, a precoding matrix generated by a MAC function or By sending a matrix or vector obtained by dividing the precoding matrix between the central station apparatus and the distributed station apparatus, the precoding matrix operation can be performed even if the functions of the physical layer are distributed.

Specifically, the central station apparatus of the present invention is a central station apparatus that controls one or more distributed station apparatuses including one or more antennas that wirelessly communicate data signals with a mobile terminal, from the distributed station apparatus. Based on the above information, a matrix required for an operation to extract a specific data signal to be transmitted from the data signal before the physical layer processing or during the physical layer processing and the data signal to the mobile terminal , It comprises a MAC (Media Access Control) function unit for generating for each of the dispersion station apparatus, and a transmission unit that transmits the data signal and the matrix corresponding to the dispersion station apparatus to the distributed stations.

  In the central station device of the present invention, the transmitting unit is an element necessary for an operation for extracting the specific data signal transmitted to the mobile terminal by all the distributed station devices to be controlled included in the matrix, A submatrix or partial vector obtained by dividing an element necessary for the calculation of extracting the specific data signal transmitted to the mobile terminal by the distributed station apparatus of the transmission destination for each of the distributed station apparatuses of the transmission destination, You may transmit to a distributed station apparatus.

Specifically, the distributed station apparatus according to the present invention provides the mobile station according to control information transmitted from a central station apparatus that controls one or more distributed station apparatuses including one or more antennas that wirelessly communicate data signals with a mobile terminal. A distributed station apparatus that wirelessly communicates data signals with a terminal, wherein a data signal before physical layer processing or in the middle of physical layer processing, and a specific data signal to be transmitted from the data signal to the mobile terminal A receiving unit that receives a matrix necessary for an operation to be extracted from the central station device; at least one modulator that modulates each data signal received by the receiving unit and generates a modulation symbol of each data signal; and the modulation It performs matrix calculation using the matrix received symbol and the receiver unit, and a calculation unit to retrieve the specific data signal to be transmitted to the mobile terminal.

  The distributed station apparatus of the present invention further includes a buffer for accumulating the data signal received by the reception unit, and the modulator sequentially reads and modulates each data signal accumulated in the buffer from the buffer, The modulation symbols for each data signal may be generated in order.

  In the distributed station apparatus of the present invention, the receiving unit is an element necessary for an operation for extracting the specific data signal transmitted to the mobile terminal by all the distributed station apparatuses to be controlled included in the matrix, The distributed station apparatus that receives the matrix receives a partial matrix or a partial vector obtained by dividing the elements necessary for calculating the specific data signal transmitted to the mobile terminal for each of the distributed station apparatuses that receive the matrix. The calculation unit may perform matrix calculation using the modulation symbol and the element of the matrix received from the central station apparatus.

  Specifically, the wireless communication system of the present invention includes a central station device and a distributed station device.

Specifically, the communication method of the central station apparatus according to the present invention is a communication method of the central station apparatus that controls one or more distributed station apparatuses including one or more antennas that wirelessly communicate data signals with a mobile terminal. Then, based on the information from the distributed station apparatus, a data signal before physical layer processing or during physical layer processing and a specific data signal to be transmitted to the mobile terminal are extracted from the data signal. A MAC (Media Access Control) function procedure for generating a matrix required for computation for each distributed station device, and a central station transmission procedure for transmitting the data signal and the matrix corresponding to the distributed station device to the distributed station device And execute .

  In the communication method of the central station apparatus according to the present invention, in the central station transmission procedure, all the distributed station apparatuses to be controlled included in the matrix perform an operation of extracting the specific data signal transmitted to the mobile terminal. Among necessary elements, a submatrix or a partial vector obtained by dividing an element necessary for an operation for extracting the specific data signal transmitted from the transmission destination distributed station apparatus to the mobile terminal for each of the transmission destination distributed station apparatuses. , It may be transmitted to the distributed station apparatus of the transmission destination.

Specifically, the communication method of the distributed station apparatus of the present invention includes control information transmitted from a central station apparatus that controls one or more distributed station apparatuses including one or more antennas that wirelessly communicate data signals with a mobile terminal. A communication method of a distributed station apparatus for wirelessly communicating a data signal with the mobile terminal according to the method, wherein a data signal before physical layer processing or in the middle of physical layer processing and transmitted from the data signal to the mobile terminal a receiving procedure for the matrix required for the operation to retrieve specific data signals received from said central station, a modulation procedure for modulating each data signal received by the receiving procedure to generate a modulated symbol of each data signal performs matrix operation using the matrix received by the modulation symbol and the received instructions, and operation procedures to retrieve specific data signal to be transmitted to the mobile terminal, the operation And instructions distributed station transmission for transmitting the specific data signal extracted in this order to the mobile terminal, the order to execute.

  In the communication method of the distributed station apparatus of the present invention, in the reception procedure, the data signal received from the central station apparatus is accumulated in a buffer, and in the modulation procedure, each data signal accumulated in the buffer is sequentially transmitted from the buffer. It may be read and modulated to generate modulation symbols for each data signal in order.

  In the communication method of the distributed station apparatus of the present invention, in the reception procedure, the receiving unit extracts the specific data signal transmitted to the mobile terminal by all the distributed station apparatuses to be controlled included in the matrix. Of the elements necessary for computation, the distributed station apparatus that receives the matrix divides the elements necessary for computation to extract the specific data signal transmitted to the mobile terminal for each distributed station apparatus that receives the matrix A partial matrix or a partial vector may be received, and matrix calculation may be performed using the modulation symbol and the matrix element received from the central station apparatus in the calculation procedure.

  The above inventions can be combined as much as possible.

  According to the present invention, a wireless communication system, a central station device, a distributed station device, a communication method for a central station device, and a distributed method capable of performing a precoding matrix operation even when the functions of the physical layer are distributed in a system configuration of Partial Centralization A station apparatus communication method can be provided.

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 an example of CoMP using two base stations is shown. A schematic diagram of an example of CoMP using one central station and two distributed stations 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 configuration of a wireless communication system according to a first embodiment. 4 shows an exemplary configuration of a wireless communication system according to a second embodiment. 6 shows an exemplary configuration of a wireless communication system according to a third embodiment. 10 shows an exemplary configuration of a wireless communication system according to a fourth embodiment. 10 illustrates an example of a configuration of a wireless communication system according to a fifth embodiment. 10 shows an exemplary configuration of a wireless communication system according to a sixth embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below. These embodiments are merely examples, and the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. 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 the present 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 present embodiment, when the number of distributed stations 92 associated with the central station 91 is 2, and the number of antennas 21 provided in each distributed station 92 is 1, different signal data is transmitted from the central station 91 to each distributed station 92. Sent. However, the number of distributed stations 92 with which the central station 91 cooperates is not limited to two, and the number of antennas 21 provided in one distributed station 92 may be plural. 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 conversion unit 14 functions as a transmission unit and is provided for each distributed station 92 connected to the central station 91.
The dispersion stations 92-1 and 92-2 include an antenna 21, 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, A conversion unit 23 is provided.

  The central station 91 executes the communication method of the central station apparatus according to the present embodiment. The communication method of the central station apparatus according to the present embodiment is a communication method of the central station 91 that controls one or more distributed stations 92 including one or more antennas that wirelessly communicate data signals with a terminal 95 that is a mobile terminal. And a central station transmission procedure.

In the central station transmission procedure, the signal converter 14 of the central station 91 transmits data signals and control information corresponding to the modulation symbols s ₁ and s ₂ to the respective distributed stations 92. The data signal is, for example, both transport blocks d ₁ and d ₂ . Control information is, for example, a DCI for both transport block _{d 1} and _{d 2.} Here, the number of data signals is equal to or less than the total number of antennas 21 included in all the distributed stations 92 to be controlled by the central station 91. In the present embodiment, since the number of antennas 21 is 2, the signal conversion unit 14 transmits the transport blocks d ₁ and d ₂ as two data signals.

Further, in the central station transmission procedure, the signal conversion unit 14 of the central station 91 applies all the precoding matrices W expressed by the following equation (2) generated by the MAC function unit 11 as the control targets of the central station 91. To the distributed station 92. Precoding matrix W acts as a matrix required for the operation performed in a distributed station 92 retrieves the specific data signal to be transmitted to the mobile terminal 95 dispersed station 92 from the transport block d ₁ and d ₂ received from the central office 91 Used for calculation. The precoding matrix W is transmitted by quantizing each element w _ij and transmitting it from the signal conversion unit 14.

  The distributed stations 92-1 and 92-2 execute the communication method of the distributed station apparatus according to the present embodiment. The communication method of the distributed station apparatus according to the present embodiment is based on the control information transmitted from the central station 91 that controls one or more distributed stations 92 including one or more antennas 21 that wirelessly communicate data signals with the terminal 95. 95 is a communication method of a distributed station apparatus that wirelessly communicates data signals with 95, and has a reception procedure, a modulation procedure, a calculation procedure, and a distributed station transmission procedure in this order.

In the reception procedure, the signal converters 22 of the distributed stations 92-1 and 92-2 receive the transport blocks d1 and d2, DCI, and the precoding matrix W from the central station 91. Further, in the reception procedure, each of the distributed stations 92-1 and 92-2 separates d ₁ and d ₂ and the precoding matrix W by the separation unit 25.

The modulation procedure, the modulation unit 24 of the distributed stations 92-1 and 92-2 performs modulation on the respective transport blocks _{d 1} and _{d 2,} to obtain the modulation symbols _{s 1} and _{s 2.} Here, physical layer processing such as CRC assignment and encoding may be performed before and after the modulation by the modulation unit 24.

The algorithm, the precoding operation unit 26 of the distributed stations 92-1 and 92-2 performs precoding matrix operation expressed by the formula (1) using the modulation symbols s ₁ and s ₂ and the precoding matrix W . Then, the dispersion station discards _{s 2p} leaving _{s 1p} In the pre-encoding calculating unit 26 of the 92-1, whereas in the preceding calculation unit 26 of the distributed stations 92-2 leaving _{s 2p} discard _{s 1p.} The modulation symbols s _1p and s _2p function as specific data signals that the distributed station 92 transmits to the mobile terminal 95.

In the distributed station transmission procedure, the D / A conversion unit 23 of each of the distributed stations 92-1 and 92-2 performs D / A conversion on each of the modulation symbols s _1p and s _2p , and after D / A conversion The analog signals s _1AN and s _2AN are transmitted from the antenna 21 to the mobile terminal 95. Here, before the D / A conversion in the D / A conversion unit 23, signal processing for performing multicarrier transmission such as OFDM may be performed on s _1p and s _2p .

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 generated from modulation symbols s _1p and s _2p that have been subjected to precoding calculation processing at the output of the antenna 21 of each distributed station 92. It can be seen that _1AN and _s2AN are obtained. Furthermore, since the transmission capacity required to send the precoding matrix W is negligibly small compared to the entire transmission capacity, the effect of reducing the transmission capacity does not change.

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

  As described above, the transmission capacity is reduced by performing signal transmission between the central station 91 and the distributed station 92 by the partial centralization to which the first to sixth embodiments of the present invention are applied instead of the full centralization currently widely used. It can be greatly reduced and CoMP using coherent JT can also be performed. The increase in transmission capacity due to sending the precoding matrix is negligibly small. However, when transmitting a matrix or vector obtained by dividing the precoding matrix compared to transmitting the precoding matrix itself, the increase in transmission capacity is more significant. It can be kept small.

  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. The transport block, DCI, and precoding matrix may be divided in the time domain, or the transport block, DCI, and precoding matrix may be sent in packets, and the DCI and precoding matrix 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) technology to the central station 91 and the distributed station 92, data can be efficiently transmitted to each distributed station using the multicast function of the PON.

(Embodiment 2)
In the wireless communication system according to the present embodiment, unlike the first embodiment, the same signal data may be transmitted to each distributed station 92. FIG. 8 shows CoMP signal transmission in Partial Centralization to which Embodiment 2 is applied.

First, the signal conversion unit 14 of the central station 91 transmits the transport block d ₁ corresponding to the modulation symbol s ₁ and the DCI related thereto to each distributed station 92, and further generates the following equation (3) generated by the MAC function unit 11: ) Is transmitted.

Signal converting unit 22 each distributed stations 92-1 and the 92-2 has is a DCI signal conversion unit 14 are involved in the transport block _{d 1} and it was transmitted, it receives the precoding vector w. The separation unit 25 separates the transport block d ₁ and the precoding vector w. Modulator 24 performs modulation of the transport block _{d 1,} to obtain the modulation symbol _{s 1.} Thereafter, the precoding calculation unit 26 performs a precoding matrix calculation represented by the following equation (4) using the modulation symbol s ₁ and the precoding vector w. For example, the precoding operation unit 26 of the dispersion station 92-1 generates _{s 1p} from modulation symbols _{s 1} and _{w 1,} precoding operation unit 26 of the dispersion station 92-2, from the modulation symbols _{s 1} and _{w 2} s ′ _1p is generated.

Thereafter, the D / A converter 23 of each of the distributed stations 92-1 and 92-2 performs D / A conversion on each of s _1p and s ^′ _1p , and transmits it from the antenna 21 as s _1AN and s ^′ _1AN. To do. Thereby, the same data signal can be simultaneously transmitted to different terminals 95.

  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, DCI, and precoding vector may be divided in the time domain, or the transport block, DCI, and precoding vector may be sent in packets, and the DCI and precoding vector 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 3)
In the wireless communication system according to the present embodiment, unlike the first embodiment, the number of the modulators 24 may be reduced by using the buffer 27 in each distributed station 92. The buffer 27 stores the transport blocks d ₁ and d ₂ received by the signal converter 22. FIG. 9 shows CoMP signal transmission in Partial Centralization to which the third embodiment is applied.

In the reception procedure according to the present embodiment, the transport blocks d ₁ and d ₂ that have arrived at the distributed stations 92-1 and 92-2 from the central station 91 and have been separated from the precoding matrix W by the separation unit 25 are stored in the buffer 27. To accumulate. In the modulation procedure according to the present embodiment, the transport blocks d ₁ and d ₂ read from the buffer 27 are sequentially modulated by the modulator 24 to obtain modulation symbols s ₁ and s ₂ . Thereafter, the separation unit 25 separates the modulation symbols s ₁ and s ₂ , the precoding matrix operation is performed by the precoding operation unit 26 as in the first embodiment, and the D / A conversion by the D / A conversion unit 23 is performed. S _1AN and s _2AN via the antenna 21. 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. The transport block, DCI, and precoding matrix may be divided in the time domain, or the transport block, DCI, and precoding matrix may be sent in packets, and the DCI and precoding matrix 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 4)
In the wireless communication system according to the present embodiment, unlike Embodiment 1, elements necessary for matrix calculation in each distributed station 92 that is the control target of the central station 91, instead of transmitting a precoding matrix to each distributed station 92. A partial matrix or a partial vector obtained by dividing the precoding matrix so as to include may be transmitted. FIG. 10 shows CoMP signal transmission in Partial Centralization to which the fourth embodiment is applied.

In the central station transmission procedure according to the present embodiment, the signal conversion unit 14 of the central station 91 transmits the modulation symbols s _1p and s that all the distributed stations 92 to be controlled included in the pre-coating matrix W transmit to the mobile terminal 95. Among the elements necessary for the precoding matrix calculation for extracting _2p , the elements required for the calculation for extracting the modulation symbols s _1p and s _2p transmitted to the mobile terminal 95 by the transmission destination distributed station 92 are determined for each distribution station 92 of the transmission destination. A partial matrix or a partial vector that is an element of the divided matrix is transmitted to the distributed station 92 of the transmission destination.

In the fourth embodiment, the central station 91 divides the precoding matrix W in addition to the transport blocks d ₁ and d ₂ and DCI into the following equation (5) in the central station transmission procedure. The vector v ₁ is sent, and the vector v ₂ shown in the following equation (6) obtained by dividing the precoding matrix W in addition to the transport blocks d ₁ and d ₂ and DCI is sent to the distributed station 92-2. The vectors v ₁ and v ₂ function as a partial matrix or a partial vector that is an element of a matrix obtained by dividing the precoding matrix W.

In this embodiment, the signal converters 22 of the distributed stations 92-1 and 92-2 transmit all the distributed stations 92-1 and 92-2 to be controlled included in the precoding matrix W to the mobile terminal 95. among the elements required for the operation to take out the modulation symbols _{s 1p} and _{s 2p,} operation to retrieve the modulation symbols _{s 1p} and _{s 2p} distributed stations 92-1 and 92-2 receiving the precoding matrix W to send to the mobile terminal 95 Are received as vectors v ₁ and v ₂ divided for each distributed station 92 that receives the precoding matrix W.

Further, in the calculation procedure according to the present embodiment, the precoding calculation unit 26 of the distributed station 92-1 obtains the modulation symbols s ₁ and s ₂ at each distributed station 92 as in the first embodiment, and then transmits them. using vector v ₁ which is performing a matrix operation represented by the following equation (7).

Similarly, tables in the operational procedure according to the present embodiment, the precoding operation unit 26 of the distributed stations 92-2 using the modulation symbols s ₁ and s ₂ and transmitted vector v ₂ of the following formula (8) Perform matrix operations.

Thereafter, in the distributed station transmission procedure according to the present embodiment, D / A conversion is performed on each of s _1p and s _2p in the D / A conversion unit 23 included in the distributed stations 92-1 and 92-2, and s _1AN And s _2AN are transmitted from the antenna 21. In the fourth embodiment, the number of elements of the matrix transmitted between the central station 91 and each distributed station 92 is smaller than in the first embodiment, and the increase in transmission capacity between the central station 91 and the distributed station 92 is made smaller. Can do.

  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 and precoding matrix elements may be divided in the time domain, the transport block and DCI and precoding matrix elements are sent in packets, and the DCI and precoding matrix elements are used as headers. It may be incorporated. 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.

(Embodiment 5)
Unlike the first embodiment, as in the fifth embodiment, the number of distributed stations 92 may not be limited to two, and the number of antennas 21 provided in each distributed station 92 may be plural. When the number of the distributed stations 92 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 21.

Further, even when the number of distributed stations 92 is plural and the number of antennas 21 provided in each distributed station 92 is plural, each distributed station 92 can perform MIMO transmission using precoding. FIG. 11 shows CoMP signal transmission in partial centralization to which the fifth embodiment is applied. 11 In a number of distributed stations 92 cooperating L (L is a natural number of 1 or more), the number of antennas 21 provided in the distributed stations 92-1 and _{N 1,} dispersed station 92-M (M = 1, ..., the number of antennas 21 provided in L) is set to _{N M.} The total number K of antennas 21 provided in all the distributed stations 92 is expressed by the following equation (9).

In the central station transmission procedure according to this embodiment, the central station 91 transmits K transport blocks from d ₁ to d _K and their corresponding DCIs to the respective distributed stations 92, and further the MAC function unit. 11 is transmitted. The K × K precoding matrix Y in this case is expressed by the following equation (10).

ここで、添字Ｍ_１及びＭ_ＮＭは、それぞれ分散局９２−Ｍの１番目およびＮ_Ｍ番目のアンテナ番号を示す。

Here, the subscript _{M 1} and _{M NM,} respectively showing a first and _{N M-th} antenna number of distributed stations 92-M.

The reception procedure according to the present embodiment, the signal conversion unit 22 of the distributed stations 92, receives a transport block _d 1 to d _K, the DCI corresponding to _{d K} from the transport block _{d 1,} a precoding matrix Y To do. In the reception procedure, the separation unit 25 of each distributed station 92 separates the K transport blocks from d ₁ to d _K and the precoding matrix Y.

In the modulation procedure, the modulator 24 modulates each transport block to obtain K modulation symbols from s ₁ to s _K. Thereafter, in the calculation procedure, the precoding unit 26 performs matrix calculation using the K modulation symbols from s ₁ to s _K and the precoding matrix Y.

Distributed station 92-M, the _{N M} number of modulation symbols after precoding _{s MNMp} from the same _{s M1p} as the number of antennas 21 provided in the dispersion station 92-M from the output of the matrix operation in the precoding calculation unit 26 Take out. In a distributed station transmission procedure, the D / A converter 23 performs D / A conversion of _{s MNMp} from modulation symbols _{s M1p precoded, N M-number} of radio signals _{s MNMAN} from _{s M1AN} is transmitted from the antenna The

For example, in the distributed station 92-1, N ₁ pre-coded modulation symbols from s _11p to s _1N1p are obtained from the output of the precoding operation unit 26. Thereafter, in the D / A converter 23, D / A conversion is performed for each of the modulation symbols precoded _and transmitted from the antenna 21 as _{N 1} pieces of radio signals _{s 1N1AN} from _{s 11AN.}

Note that any or all of the methods shown in the second, third, and fourth embodiments may be applied to the fifth embodiment, and the number of transport blocks may be K or less. 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. The transport block, DCI, and precoding matrix may be divided in the time domain, or the transport block, DCI, and precoding matrix may be sent in packets, and the DCI and precoding matrix 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 6)
Unlike the first embodiment, as in the sixth embodiment, the number of the distributed stations 92 may not be limited to two, and the number of the antennas 21 provided in each distributed station 92 is plural, and the central station 91 is also provided. May transmit to each distributed station 92 a partial matrix or partial vector obtained by dividing the precoding matrix so as to include elements necessary for matrix operation in each distributed station instead of the precoding matrix.

FIG. 12 shows CoMP signal transmission in Partial Centralization to which Embodiment 6 is applied. Symbols indicating numbers are the same as those in the fifth embodiment and FIG. In the sixth embodiment, the signal conversion unit 14 of the central station 91 performs the following processing by dividing from the precoding matrix Y instead of the precoding matrix Y to the distributed stations 92-1 to 92-M in the central station transmission procedure. Only the N _M × K matrix Y _M expressed by Equation (11) is sent.

For example, in the distributed station 92-M, in the calculation procedure, similarly to the fifth embodiment, the K modulation symbols obtained through the reception procedure and the modulation procedure and the matrix element Y _M received by each distributed station 92 are used to form a matrix. Perform the operation. The output of the matrix operation of a distributed station 92-M precoding calculation unit 26, to give _{N M} number of modulation symbols after precoding _{s MNMp} from the same _{s M1p} as the number of antennas 21 provided in the dispersion station 92-M is It is done. In a distributed station transmission procedure, D / A conversion by the D / A converter 23 modulation symbols precoded, _{N M-number} of radio signals _{s MNMAN} is transmitted from the antenna 21 from the _{s M1AN} after D / A conversion . The processing is the same in other distributed stations 92.

Note that any or all of the methods shown in the second, third, and fourth embodiments may be applied to the sixth embodiment, and the number of transport blocks may be K or less. 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. In the sixth embodiment, the number of elements of the matrix transmitted between the central station 91 and each distributed station 92 is smaller than in the fifth embodiment, and the increase in transmission capacity between the central station 91 and the distributed station 92 is made smaller. Can do.

  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. Further, the transport block, DCI, and the matrix after division may be divided in the time domain, or the transport block, DCI, and elements of the divided matrix are sent in packets, and DCI and elements of the divided matrix are headers. It may be incorporated into. 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.

  The wireless communication system, the central station device, the distributed station device, the communication method of the central station device, and the communication method of the distributed station device of the present invention can be applied to the 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 stations 92, 92-1, 92-2: Distributed station 93: Core network 94: Base station 95: Terminal

Claims (9)

A central station apparatus that controls one or more distributed station apparatuses including one or more antennas that wirelessly communicate data signals with a mobile terminal,
Based on information from the distributed station device, an operation for extracting a data signal before physical layer processing or in the middle of physical layer processing and a specific data signal to be transmitted to the mobile terminal from the data signal A MAC (Media Access Control) function unit that generates a necessary matrix for each distributed station device;
A transmission unit for transmitting the data signal and the matrix corresponding to the distributed station device to the distributed station device ;
A central station apparatus comprising: A central station apparatus that controls one or more distributed station apparatuses including one or more antennas that wirelessly communicate data signals with a mobile terminal,
The number of the data signals equal to or less than the total number of the antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data signals with the mobile terminal, All of the distributed station devices to be controlled by the central station device include a matrix necessary for an operation to extract a specific data signal to be transmitted to the mobile terminal from the data signal received by the distributed station device from the central station device. A transmission unit for transmitting to
The transmitter is
Among the elements necessary for the operation of extracting the specific data signal transmitted to the mobile terminal by all the distributed station devices to be controlled included in the matrix, the distributed station device of the transmission destination transmits to the mobile terminal Transmitting a partial matrix or a partial vector obtained by dividing each element necessary for the operation for extracting the specific data signal for each of the distributed station apparatuses of the transmission destination to the distributed station apparatus of the transmission destination ;
Medium Hisashikyoku apparatus. A distributed station apparatus that wirelessly communicates data signals with the mobile terminal according to control information transmitted from a central station apparatus that controls one or more distributed station apparatuses including one or more antennas that wirelessly communicate data signals with the mobile terminal. And
Reception to receive from the central station apparatus a matrix required for an operation to extract a data signal before processing of the physical layer or in the middle of processing of the physical layer, and a specific data signal to be transmitted to the mobile terminal from the data signal And
At least one modulator that modulates each data signal received by the receiver and generates a modulation symbol of each data signal;
A calculation unit to retrieve specific data signal matrix operation was carried out, and transmits to the mobile terminal using said received matrix of the modulated symbols and the receiving unit,
A distributed station apparatus comprising: A distributed station apparatus that wirelessly communicates data signals with the mobile terminal according to control information transmitted from a central station apparatus that controls one or more distributed station apparatuses including one or more antennas that wirelessly communicate data signals with the mobile terminal. And
The number of the data signals equal to or less than the total number of the antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data signals with the mobile terminal, A reception unit that receives from the central station device a matrix necessary for an operation to extract a specific data signal to be transmitted to the mobile terminal from the data signal received from the central station device performed by the distributed station device;
At least one modulator that modulates each data signal received by the receiver and generates a modulation symbol of each data signal;
A calculation unit that performs matrix calculation using the modulation symbol and the matrix received by the reception unit, and extracts a specific data signal to be transmitted to the mobile terminal;
With
The receiver is
Among the elements necessary for the operation to extract the specific data signal transmitted to the mobile terminal by all the distributed station devices to be controlled included in the matrix, the distributed station device that receives the matrix is the mobile terminal. Receiving a partial matrix or a partial vector obtained by dividing the elements necessary for the operation of extracting the specific data signal to be transmitted for each of the distributed station apparatuses receiving the matrix;
The computing unit is
A matrix operation is performed using the modulation symbol and the element of the matrix received from the central station device .
Minute Chikyoku apparatus. The central office device according to claim 1 or 2,
The distributed station apparatus according to claim 3 or 4 ,
A wireless communication system comprising: A communication method of a central station apparatus for controlling one or more distributed station apparatuses provided with one or more antennas for wirelessly communicating data signals with a mobile terminal,
Based on information from the distributed station device, an operation for extracting a data signal before physical layer processing or in the middle of physical layer processing and a specific data signal to be transmitted to the mobile terminal from the data signal A MAC (Media Access Control) function procedure for generating a necessary matrix for each distributed station device;
A central station transmission procedure for transmitting the data signal and the matrix corresponding to the distributed station device to the distributed station device ;
Communication method Hisashikyoku device in that perform. A communication method of a central station apparatus for controlling one or more distributed station apparatuses provided with one or more antennas for wirelessly communicating data signals with a mobile terminal,
The number of the data signals equal to or less than the total number of the antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data signals with the mobile terminal, All of the distributed station devices to be controlled by the central station device include a matrix necessary for an operation to extract a specific data signal to be transmitted to the mobile terminal from the data signal received by the distributed station device from the central station device. Execute the central office transmission procedure to transmit to
In the central station transmission procedure,
Among the elements necessary for the operation of extracting the specific data signal transmitted to the mobile terminal by all the distributed station devices to be controlled included in the matrix, the distributed station device of the transmission destination transmits to the mobile terminal Transmitting a partial matrix or a partial vector obtained by dividing each element necessary for the operation for extracting the specific data signal for each of the distributed station apparatuses of the transmission destination to the distributed station apparatus of the transmission destination ;
Communication method of the middle Hisashikyoku apparatus. Communication of a distributed station apparatus that wirelessly communicates data signals with the mobile terminal according to control information transmitted from a central station apparatus that controls one or more distributed station apparatuses provided with one or more antennas that wirelessly communicate data signals with the mobile terminal A method,
Reception to receive from the central station apparatus a matrix required for an operation to extract a data signal before processing of the physical layer or in the middle of processing of the physical layer, and a specific data signal to be transmitted to the mobile terminal from the data signal Procedure and
A modulation procedure for modulating each data signal received by the receiving procedure to generate a modulated symbol of the respective data signals,
A calculation procedure for performing a matrix operation using the modulation symbol and the matrix received in the reception procedure, and for extracting a specific data signal to be transmitted to the mobile terminal ;
A distributed station transmission procedure for transmitting the specific data signal extracted in the calculation procedure to the mobile terminal;
The communication method of the distributed station apparatus which performs sequentially. Communication of a distributed station apparatus that wirelessly communicates data signals with the mobile terminal according to control information transmitted from a central station apparatus that controls one or more distributed station apparatuses provided with one or more antennas that wirelessly communicate data signals with the mobile terminal A method,
The number of the data signals equal to or less than the total number of the antennas provided in all the distributed station devices to be controlled by the central station device, and control information for wirelessly communicating the data signals with the mobile terminal, A reception procedure for receiving from the central station device a matrix necessary for an operation to extract a specific data signal to be transmitted to the mobile terminal from the data signal received from the central station device performed by the distributed station device;
A modulation procedure for modulating each data signal received in the reception procedure and generating a modulation symbol for each data signal;
A calculation procedure for performing a matrix operation using the modulation symbol and the matrix received in the reception procedure, and for extracting a specific data signal to be transmitted to the mobile terminal;
A distributed station transmission procedure for transmitting the specific data signal extracted in the calculation procedure to the mobile terminal;
In order,
In the receiving procedure ,
Among the elements needed for operation the retrieve specific data signals prior SL matrix all of the distributed station apparatus to be controlled included in is transmitted to the mobile terminal, the dispersion station apparatus wherein receiving said matrix mobile Receiving a partial matrix or a partial vector obtained by dividing the elements necessary for the operation of extracting the specific data signal to be transmitted to the terminal for each of the distributed station apparatuses that receive the matrix;
In the calculation procedure,
Performing matrix operations using the modulation symbols and the elements of the matrix received from the central station device ;
Communication method of minute Chikyoku apparatus.

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