WO2024070445A1 - Processing apparatus that communicates with wireless devices via multiple access point devices - Google Patents

Processing apparatus that communicates with wireless devices via multiple access point devices Download PDF

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Publication number
WO2024070445A1
WO2024070445A1 PCT/JP2023/031468 JP2023031468W WO2024070445A1 WO 2024070445 A1 WO2024070445 A1 WO 2024070445A1 JP 2023031468 W JP2023031468 W JP 2023031468W WO 2024070445 A1 WO2024070445 A1 WO 2024070445A1
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devices
wireless
reference signal
processing device
srs
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PCT/JP2023/031468
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French (fr)
Japanese (ja)
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一生 菅野
武雄 大関
良晃 天野
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Kddi株式会社
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0446—Resources in time domain, e.g. slots or frames
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/20—Control channels or signalling for resource management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W92/00—Interfaces specially adapted for wireless communication networks
    • H04W92/16—Interfaces between hierarchically similar devices
    • H04W92/20—Interfaces between hierarchically similar devices between access points

Definitions

  • the present disclosure relates to a mobile communication system that communicates with a wireless device (WD) via multiple access point (AP) devices.
  • WD wireless device
  • AP access point
  • a central processing unit (CPU) located in an aggregate station communicates with wireless devices (WDs) via multiple access points (APs) located at different geographical locations.
  • the AP device located in each AP is simply referred to as "AP" below.
  • the AP has an antenna and a wireless device.
  • the wireless device has a wireless transmitter (TX) that transmits wireless signals to the WD via the antenna, and a wireless receiver (RX) that receives wireless signals from the WD via the antenna.
  • TX wireless transmitter
  • RX wireless receiver
  • the communication link connecting the CPU of the aggregate station and the AP is also called a fronthaul.
  • the CPU generates a transmission signal based on data to be sent to one or more WDs, and sends the generated transmission signal to the TX of each of the multiple APs.
  • the TX of each AP transmits a wireless signal via an antenna based on the transmission signal from the CPU.
  • the RX of each AP receives wireless signals from one or more WDs via an antenna.
  • the RX of each AP transmits a received signal based on the received wireless signal to the CPU.
  • the CPU demodulates the data from each WD based on the received signal from each AP.
  • the CPU precodes a transmission signal generated based on data to be transmitted to one or more WDs based on the downlink (DL) channel matrix between the one or more WDs and transmits the signal to each of the multiple APs.
  • DL downlink
  • the DL channel matrix can be estimated based on a reference signal or standard signal that the CPU receives from one or more WDs via each AP.
  • Patent Documents 1 and 2 disclose a configuration in which test signals are transmitted and received between multiple APs to obtain the ratio of the TX and RX transfer functions of a reference AP among multiple APs to the TX and RX transfer functions of other APs, and the DL channel matrix is obtained by correcting the UL channel matrix based on the ratio.
  • Patent Documents 1 and 2 it is necessary to add a new function to the CPU that allows the AP to estimate channel characteristics based on test signals received from other APs.
  • This disclosure provides a technique for estimating channel characteristics between APs without adding a new estimation function.
  • AP access point
  • FIG. 1 is a configuration diagram of a mobile communication system according to an embodiment.
  • FIG. 2 is a block diagram of a processing device according to an embodiment.
  • FIG. 1 is a diagram showing the configuration of a mobile communication system according to this embodiment.
  • the mobile communication system includes a CPU 1, N (N is an integer of 2 or more) access point devices (APs) 2, and two WDs 3.
  • N is an integer of 2 or more
  • APs access point devices
  • WDs 3 are written as WD#1 to AP#N as shown in FIG. 1.
  • WD#1 and WD#2 are written as shown in FIG. 1.
  • the number of WDs 3 is 2 in FIG. 1, the number of WDs 3 can be any number of 1 or more.
  • the mobile communication system according to this embodiment uses time division duplex (TDD).
  • TDD time division duplex
  • the downlink (DL) from AP 2 to WD 3 and the uplink (UL) from WD 3 to AP 2 are separated by time, and the frequency band of the radio signal used in the DL direction is the same as that of the radio signal used in the UL direction.
  • CPU1 is a processing device (also referred to as a central processing device) located in the aggregation station, and as described above, is connected to N APs 2 via the fronthaul. For example, when CPU1 transmits data to WD#1 and WD#2, CPU1 generates a transmission signal including data addressed to WD#1 and WD#2, and transmits the generated transmission signal to each of APs#1 to AP#N.
  • APs#1 to AP#N each have a TX and RX, and one or more antennas.
  • APs#1 to AP#N transmit wireless signals based on the transmission signal from CPU1. The wireless signals transmitted by each of APs#1 to AP#N are received by WD#1 and WD#2.
  • each of AP#1 to AP#N receives wireless signals from WD#1 and WD#2 and transmits a received signal corresponding to the wireless signal to CPU1.
  • the wireless signals from WD#1 and WD#2 include data that WD#1 and WD#2 transmit to the communication partner.
  • CPU1 estimates the data from WD#1 and WD#2 based on the received signals from AP#1 to AP#N.
  • the transmitter 13 generates a transmission signal based on transmission data addressed to WD #1 and WD #2, and precodes the transmission signal based on the DL channel matrix H DL notified by the control unit 10.
  • a transmission signal to be transmitted to each AP 2 is generated by precoding the transmission signal.
  • the receiver 14 outputs reception data from WD #1 and WD #2 based on the reception signal from each AP 2.
  • the receiver 14 also outputs a sounding reference signal (SRS) contained in each received signal transmitted by WD#1 and WD#2 and received from each AP 2 to the characteristic estimator 12.
  • SRS is a reference signal that is transmitted by WD3 to estimate UL channel characteristics between WD3 and the AP 2 and is defined in the standard of the Third Generation Partnership Project (3GPP).
  • the characteristic estimator 12 estimates a UL channel matrix H UL between WD#1 and WD#2 based on the SRS received from WD#1 and WD#2, and notifies the control unit 10 of the estimation.
  • the control unit 10 estimates the channel matrix H DL by correcting the channel matrix H UL with the correction matrix C and notifies the transmission unit 13.
  • the control unit 10 executes a calibration process (correction process).
  • the control unit 10 controls the APs #1 to #N to transmit and receive test signals between the APs 2.
  • the characteristic estimation unit 12 acquires the test signals received by each AP 2 from each AP 2, and obtains the ratio of the transfer functions of the TX and RX of the other AP 2 to the transfer functions of the TX and RX of the reference AP among the multiple APs 2 as a correction coefficient.
  • the characteristic estimation unit 12 generates a correction matrix C, which is a diagonal matrix with the correction coefficients as diagonal elements, and notifies the control unit 10.
  • the SRS which is the UL reference signal described above, is used as the test signal transmitted and received between AP2 to generate this correction matrix C.
  • the control unit 10 determines the radio resources (timing and frequency band) and the SRS sequence used by each WD 3 for transmitting the SRS, and presets the determined radio resources and sequence in each WD 3 via a higher layer protocol.
  • the transmission timing of the SRS is the timing within a period in which the WD 3 transmits a radio signal in the UL direction.
  • the radio resources and the SRS sequence for transmitting the SRS are determined within a range defined by the 3GPP standard. In the following description, the radio resources for transmitting the SRS preset in the WD 3 are referred to as "WD radio resources".
  • the operation of the control unit 10 for executing the calibration process is described below.
  • the calibration process can be executed when a new AP2 is added, when the TX or RX of the AP2 is replaced, or when it is estimated that the characteristics of the TX or RX of the AP2 have changed significantly due to aging or temperature changes in the equipment.
  • the control unit 10 schedules the timing for each AP2 to transmit and receive SRS. Specifically, the control unit 10 decides which series of SRS each AP2 will transmit and which wireless resource will be used. The control unit 10 selects a wireless resource that the AP2 will use to transmit SRS from among available wireless resources that are specified as being usable for transmitting SRS in standards such as 3GPP and that are different from the "WD wireless resource.” In the calibration process, the AP2 normally transmits the SRS for calibration during the period in which it receives a wireless signal from the WD3. Therefore, the timing for the AP2 to transmit the SRS is determined so that it does not need to receive a wireless signal.
  • AP#1 to AP#N are each set as a transmitting AP in turn, and the control unit 10 schedules the SRS so that at a certain timing, only one transmitting AP transmits the SRS, and the remaining AP2 (receiving AP) receives the SRS from the transmitting AP.
  • SRS can be transmitted and received between any two AP2 pairs among AP#1 to AP#N.
  • the control unit 10 notifies the transmission unit 13 of the scheduling result and calibration information indicating the sequence of the SRS transmitted by each AP.
  • the control unit 10 also transmits timing information to each AP 2.
  • the timing information is information indicating the timing of transmitting the SRS to each AP 2.
  • the AP 2 transmits the SRS during the period in which it receives a wireless signal from the WD 3. For this reason, the control unit 10 needs to notify each AP 2 of the timing of transmitting the SRS.
  • the control unit 10 After transmitting the calibration information to the transmission unit 13 and the timing information to each AP 2, the control unit 10 notifies the transmission unit 13 and each AP 2 of the start of the calibration process when starting the calibration process.
  • the transmission unit 13 inserts an SRS into the transmission signal of each AP 2 according to the calibration information, and each AP 2 controls TX and RX so that the SRS is transmitted according to the timing information.
  • the generation unit 131 of the transmission unit 13 generates an SRS to be transmitted by the AP 2 according to the calibration information and inserts it into the transmission signal to the AP 2. Note that a configuration may be adopted in which the start of the calibration process is notified to the transmission unit 13 and each AP 2 by transmitting the calibration information and the timing information to the transmission unit 13 and each AP 2.
  • the control unit 10 notifies the transmission unit 13 and each AP 2 of the end of the calibration process.
  • the transmitter 13 stops transmitting the SRS to each AP 2.
  • each AP 2 stops controlling TX to transmit the SRS during the wireless signal reception period.
  • the characteristic estimation unit 12 first estimates the channel characteristic between AP2 based on the SRS from other AP2 received by each AP2.
  • the calibration information is also notified to the processing unit 11. For example, based on the SRS transmitted by AP#1 and received by each of AP#2 to AP#N, the processing unit 11 can estimate the channel characteristic values h 1,2 to h 1, N from AP#1 to AP#2 to AP#N, respectively. Similarly, based on the SRS transmitted by each of AP#2 to AP#N and received by AP#1, the processing unit 11 can estimate the channel characteristic values h 2,1 to h N,1 from each of AP#2 to AP#N to AP#1, respectively.
  • h1,2 TX1 ⁇ hp1-2 ⁇ RX2
  • h2,1 TX2 ⁇ hp2-1 ⁇ RX1
  • hp1-2 is the transfer function of the wireless section from AP#1 to AP#2
  • hp2-1 is the transfer function of the wireless section from AP#2 to AP#1.
  • the correction coefficient C 1,2 is the ratio of the transfer functions of TX and RX of AP#2 based on the transfer functions of TX and RX of AP#1.
  • the characteristic estimation unit 12 first selects one of the N APs 2 as the reference AP.
  • the selection criteria for the reference AP are arbitrary, but for example, the signal-to-noise ratio (SNR) can be estimated based on the SRS received by the AP 2, and the AP 2 with the best average SNR with other APs 2 can be selected as the reference AP.
  • SNR signal-to-noise ratio
  • AP #1 is selected as the reference AP.
  • the characteristic estimation unit 12 notifies the control unit 10 of the correction matrix C.
  • the control unit 10 estimates the DL channel matrix H DL by multiplying the UL channel matrix H UL by the inverse matrix of the correction matrix C.
  • the transmission unit 13 performs precoding by generating a precoding matrix W by a method such as ZF, MMSE, or PMMSE based on the DL channel matrix H DL .
  • a precoding matrix W by a method such as ZF, MMSE, or PMMSE based on the DL channel matrix H DL .
  • each column of the precoding matrix W corresponds to one AP2, and a transmission signal to the AP2 is multiplied by a vector of the corresponding column of the precoding matrix W.
  • the SRS which is a UL reference signal
  • the CPU 1 has a function of estimating channel characteristics based on the SRS in order to estimate the UL channel matrix H UL . Therefore, it is possible to estimate channel characteristics between the APs without adding a new estimation function.
  • AP#1 to AP#N are each set as a transmitting AP in order, and only one transmitting AP transmits SRS at a certain timing, and the remaining AP2 (receiving AP) is scheduled to receive SRS from the transmitting AP.
  • This is because, by scheduling in this way, SRS is transmitted and received in any two pairs of AP2 among AP#1 to AP#N.
  • AP#1 transmits SRS at a certain timing
  • AP#2 to AP#N receive SRS, so that the channel characteristic values h 1,2 to h 1,N can be estimated.
  • multiple APs 2 can transmit SRS using different frequency bands at a certain timing
  • APs #2 to #N transmit SRS
  • AP #1 receives SRS, so that channel characteristic values h 2,1 to h N,1 can be estimated, and thus correction matrix C can be estimated.
  • h 2,1 can be obtained by multiplying h 2,m and h m,1 . Note that m is any number from 3 to N.
  • a reference AP or a plurality of candidate APs to be the reference AP can be determined or selected in advance based on the placement positions of APs #1 to AP #N, it is not necessary to schedule transmission and reception of SRS in any pair of two APs 2.
  • the mobile communication system uses TDD.
  • the above embodiment can be applied to a mobile communication system that uses frequency division duplex (FDD) as long as reciprocity of the wireless channel is recognized even in FDD.
  • FDD frequency division duplex
  • SRS which is a UL reference signal
  • the present disclosure is not limited to the use of SRS, and any reference signal transmitted by WD3 in UL can be used for calibration.
  • channel matrix is information indicating the characteristics of multiple channels
  • precoding matrix is information indicating the processing to be applied to wireless signals transmitted from multiple APs 2
  • correction matrix is information indicating the amount of correction for the values of each element of the channel matrix. Therefore, the term “matrix" can be replaced with the term "information.”
  • the CPU1 may be realized by a computer program that, when executed by one or more processors of a device having the processors, causes the device to function as the CPU1.
  • the computer program may include program instructions that are executable by one or more processors.
  • the computer program may be stored in a non-transitory computer-readable storage medium or may be distributed via a network.

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  • Computer Networks & Wireless Communication (AREA)
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Abstract

This processing apparatus comprises: a first estimation means that is configured to estimate, on the basis of a reference signal received from one or more wireless devices via each of a plurality of APs, first channel information indicating uplink channel characteristics; a control means that is configured to perform a correction process by scheduling the transmission/reception of the reference signal by the plurality of AP devices, and by acquiring, from each of the plurality of AP devices, the reference signal received by each of the plurality of AP devices from the other AP devices, the correction process generating correction information based on a basis AP apparatus among the plurality of AP apparatuses; and a second estimation means that is configured to estimate, on the basis of the first channel information and the correction information, second channel information indicating downlink channel characteristics.

Description

複数のアクセスポイント装置を介して無線デバイスと通信する処理装置PROCESSING DEVICE FOR COMMUNICATING WITH WIRELESS DEVICES VIA A PLURALITY OF ACCESS POINT DEVICES - Patent application
　本開示は、複数のアクセスポイント（ＡＰ）装置を介して無線デバイス（ＷＤ）と通信する移動通信システムに関する。 The present disclosure relates to a mobile communication system that communicates with a wireless device (WD) via multiple access point (AP) devices.
　例えば、セルフリー大規模ＭＩＭＯ（ＣＦｍＭＩＭＯ）において、集約局に配置される中央処理装置（ＣＰＵ）は、異なる地理的位置に配置された複数のアクセスポイント（ＡＰ）を介して無線デバイス（ＷＤ）と通信する。各ＡＰに配置されるＡＰ装置を以下では単に"ＡＰ"と表記する。ＡＰは、アンテナと、無線装置と、を有する。なお、無線装置は、アンテナを介して無線信号をＷＤに送信する無線送信装置（ＴＸ）と、アンテナを介してＷＤから無線信号を受信する無線受信装置（ＲＸ）と、を有する。集約局のＣＰＵと、ＡＰとを接続する通信リンクは、フロントホールとも呼ばれる。 For example, in cell-free massive MIMO (CFmMIMO), a central processing unit (CPU) located in an aggregate station communicates with wireless devices (WDs) via multiple access points (APs) located at different geographical locations. The AP device located in each AP is simply referred to as "AP" below. The AP has an antenna and a wireless device. The wireless device has a wireless transmitter (TX) that transmits wireless signals to the WD via the antenna, and a wireless receiver (RX) that receives wireless signals from the WD via the antenna. The communication link connecting the CPU of the aggregate station and the AP is also called a fronthaul.
　ＣＰＵは、１つ又は複数のＷＤに送信するデータに基づき送信信号を生成し、生成した送信信号を複数のＡＰそれぞれのＴＸに送信する。各ＡＰのＴＸは、ＣＰＵからの送信信号に基づきアンテナを介して無線信号を送信する。また、各ＡＰのＲＸは、アンテナを介して１つ又は複数のＷＤからの無線信号を受信する。各ＡＰのＲＸは、受信した無線信号に基づく受信信号をＣＰＵに送信する。ＣＰＵは、各ＡＰからの受信信号に基づき各ＷＤからのデータを復調する。 The CPU generates a transmission signal based on data to be sent to one or more WDs, and sends the generated transmission signal to the TX of each of the multiple APs. The TX of each AP transmits a wireless signal via an antenna based on the transmission signal from the CPU. The RX of each AP receives wireless signals from one or more WDs via an antenna. The RX of each AP transmits a received signal based on the received wireless signal to the CPU. The CPU demodulates the data from each WD based on the received signal from each AP.
　ここで、ＣＰＵは、１つ以上のＷＤに送信するデータに基づき生成した送信信号を、当該１つ以上のＷＤとの間の下りリンク（ＤＬ）のチャネル行列に基づきプリコーディングして複数のＡＰそれぞれに送信する。例えば、時分割複信（ＴＤＤ）の様に、ＤＬのチャネル特性と上りリンク（ＵＬ）のチャネル特性に相反性が認められる場合、ＤＬチャネル行列は、ＣＰＵが各ＡＰを介して１つ以上のＷＤから受信する参照信号又は基準信号に基づき推定することができる。 Here, the CPU precodes a transmission signal generated based on data to be transmitted to one or more WDs based on the downlink (DL) channel matrix between the one or more WDs and transmits the signal to each of the multiple APs. For example, in the case of time division duplex (TDD), when there is a contradiction between the DL channel characteristics and the uplink (UL) channel characteristics, the DL channel matrix can be estimated based on a reference signal or standard signal that the CPU receives from one or more WDs via each AP.
　しかしながら、無線区間のチャネル特性に相反性が認められたとしても、一般的に、各ＡＰのＴＸ及びＲＸの特性は互いに異なる。このため、特許文献１及び特許文献２は、複数のＡＰ間で試験信号を送受信することで、複数のＡＰの内の基準ＡＰのＴＸ及びＲＸの伝達関数に対する他のＡＰのＴＸ及びＲＸの伝達関数の比を求め、これによりＵＬチャネル行列を補正することでＤＬチャネル行列を求める構成を開示している。 However, even if reciprocity is recognized in the channel characteristics of the wireless section, the TX and RX characteristics of each AP are generally different from each other. For this reason, Patent Documents 1 and 2 disclose a configuration in which test signals are transmitted and received between multiple APs to obtain the ratio of the TX and RX transfer functions of a reference AP among multiple APs to the TX and RX transfer functions of other APs, and the DL channel matrix is obtained by correcting the UL channel matrix based on the ratio.
特開２０１９－０９１９７４号公報JP 2019-091974 A 特開２０１９－００４３４５号公報JP 2019-004345 A
　特許文献１及び特許文献２の構成では、ＡＰが他のＡＰから受信した試験信号に基づきチャネル特性を推定する機能をＣＰＵに新たに追加する必要がある。 In the configurations of Patent Documents 1 and 2, it is necessary to add a new function to the CPU that allows the AP to estimate channel characteristics based on test signals received from other APs.
　本開示は、新たな推定機能を追加することなくＡＰ間のチャネル特性を推定する技術を提供するものである。 This disclosure provides a technique for estimating channel characteristics between APs without adding a new estimation function.
　本開示の一態様によると、無線信号の送受信を行う複数のアクセスポイント（ＡＰ）装置を介して１つ以上の無線デバイスと通信する処理装置は、前記１つ以上の無線デバイスから前記複数のＡＰ装置それぞれを介して受信する参照信号に基づき前記１つ以上の無線デバイスとの間の上りリンクのチャネル特性を示す第１チャネル情報を推定する様に構成された第１推定手段と、前記複数のＡＰ装置による前記参照信号の送受信をスケジューリングし、前記複数のＡＰ装置のそれぞれが他のＡＰ装置から受信した前記参照信号を、前記複数のＡＰ装置それぞれから取得することで、前記複数のＡＰ装置の内の基準ＡＰ装置を基準とした補正情報を生成する補正処理を行う様に構成された制御手段と、前記第１チャネル情報と前記補正情報とに基づき、前記１つ以上の無線デバイスとの間の下りリンクのチャネル特性を示す第２チャネル情報を推定する様に構成された第２推定手段と、を備えている。 According to one aspect of the present disclosure, a processing device that communicates with one or more wireless devices via a plurality of access point (AP) devices that transmit and receive wireless signals includes a first estimation means configured to estimate first channel information indicating channel characteristics of an uplink between the one or more wireless devices based on a reference signal received from the one or more wireless devices via each of the plurality of AP devices, a control means configured to schedule the transmission and reception of the reference signal by the plurality of AP devices, and perform a correction process to generate correction information based on a reference AP device among the plurality of AP devices by acquiring from each of the plurality of AP devices the reference signal that each of the plurality of AP devices received from another AP device, and a second estimation means configured to estimate second channel information indicating channel characteristics of a downlink between the one or more wireless devices based on the first channel information and the correction information.
　本開示によると、新たな推定機能を追加することなくＡＰ間のチャネル特性を推定することができる。 According to this disclosure, it is possible to estimate channel characteristics between APs without adding any new estimation functions.
　本発明のその他の特徴及び利点は、添付図面を参照とした以下の説明により明らかになるであろう。なお、添付図面においては、同じ若しくは同様の構成には、同じ参照番号を付す。 Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar components are designated by the same reference numerals.
一実施形態による移動通信システムの構成図。1 is a configuration diagram of a mobile communication system according to an embodiment. 一実施形態による処理装置の構成図。FIG. 2 is a block diagram of a processing device according to an embodiment.
　以下、添付図面を参照して実施形態を詳しく説明する。なお、以下の実施形態は特許請求の範囲に係る発明を限定するものではなく、また実施形態で説明されている特徴の組み合わせの全てが発明に必須のものとは限らない。実施形態で説明されている複数の特徴のうちの二つ以上の特徴が任意に組み合わされてもよい。また、同一若しくは同様の構成には同一の参照番号を付し、重複した説明は省略する。 The embodiments are described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. In addition, the same reference numbers are used for the same or similar configurations, and duplicate descriptions will be omitted.
　図１は、本実施形態による移動通信システムの構成図である。移動通信システムは、ＣＰＵ１と、Ｎ個（Ｎは２以上の整数）のアクセスポイント装置（ＡＰ）２と、２つのＷＤ３と、を有する。なお、以下の説明において、各ＡＰ２を区別する場合には、図１に示す様にＡＰ＃１～ＡＰ＃Ｎと表記する。同様に、２つのＷＤ３を区別する場合には、図１に示す様にＷＤ＃１及びＷＤ＃２と表記する。なお、図１においてはＷＤ３の数を２としているが、ＷＤ３の数は１以上の任意の数であり得る。なお、本実施形態による移動通信システムは、時分割複信（ＴＤＤ）を使用する。つまり、ＡＰ２からＷＤ３への方向である下りリンク（ＤＬ）とＷＤ３からＡＰ２への方向である上りリンク（ＵＬ）は時間により区切られ、ＤＬ方向に使用される無線信号と、ＵＬ方向に使用される無線信号の周波数帯域は同じである。 FIG. 1 is a diagram showing the configuration of a mobile communication system according to this embodiment. The mobile communication system includes a CPU 1, N (N is an integer of 2 or more) access point devices (APs) 2, and two WDs 3. In the following description, when each AP 2 is to be distinguished, they are written as AP#1 to AP#N as shown in FIG. 1. Similarly, when two WDs 3 are to be distinguished, they are written as WD#1 and WD#2 as shown in FIG. 1. Although the number of WDs 3 is 2 in FIG. 1, the number of WDs 3 can be any number of 1 or more. The mobile communication system according to this embodiment uses time division duplex (TDD). In other words, the downlink (DL) from AP 2 to WD 3 and the uplink (UL) from WD 3 to AP 2 are separated by time, and the frequency band of the radio signal used in the DL direction is the same as that of the radio signal used in the UL direction.
　ＣＰＵ１は、集約局に配置される処理装置（中央処理装置としても参照される）であり、上述した様に、フロントホールを介してＮ個のＡＰ２に接続される。例えば、ＣＰＵ１がＷＤ＃１及びＷＤ＃２にデータを送信する場合、ＣＰＵ１は、ＷＤ＃１及びＷＤ＃２宛のデータを含む送信信号を生成し、生成した送信信号をＡＰ＃１～ＡＰ＃Ｎそれぞれに送信する。ＡＰ＃１～ＡＰ＃Ｎは、それぞれ、ＴＸ及びＲＸと、１つ以上のアンテナと、を有する。ＡＰ＃１～ＡＰ＃Ｎは、ＣＰＵ１からの送信信号に基づき無線信号を送信する。ＡＰ＃１～ＡＰ＃Ｎそれぞれによって送信された無線信号は、ＷＤ＃１及びＷＤ＃２によって受信される。 CPU1 is a processing device (also referred to as a central processing device) located in the aggregation station, and as described above, is connected to N APs 2 via the fronthaul. For example, when CPU1 transmits data to WD#1 and WD#2, CPU1 generates a transmission signal including data addressed to WD#1 and WD#2, and transmits the generated transmission signal to each of APs#1 to AP#N. APs#1 to AP#N each have a TX and RX, and one or more antennas. APs#1 to AP#N transmit wireless signals based on the transmission signal from CPU1. The wireless signals transmitted by each of APs#1 to AP#N are received by WD#1 and WD#2.
　また、ＡＰ＃１～ＡＰ＃Ｎそれぞれは、ＷＤ＃１及びＷＤ＃２からの無線信号を受信して、当該無線信号に対応する受信信号をＣＰＵ１に送信する。なお、ＷＤ＃１及びＷＤ＃２からの無線信号は、ＷＤ＃１及びＷＤ＃２が通信相手に送信するデータを含む。ＣＰＵ１は、ＡＰ＃１～ＡＰ＃Ｎそれぞれからの受信信号に基づきＷＤ＃１及びＷＤ＃２からのデータを推定する。 In addition, each of AP#1 to AP#N receives wireless signals from WD#1 and WD#2 and transmits a received signal corresponding to the wireless signal to CPU1. The wireless signals from WD#1 and WD#2 include data that WD#1 and WD#2 transmit to the communication partner. CPU1 estimates the data from WD#1 and WD#2 based on the received signals from AP#1 to AP#N.
　図２は、本実施形態によるＣＰＵ１の構成図である。送信部１３は、ＷＤ＃１及びＷＤ＃２宛の送信データに基づき送信信号を生成し、制御部１０から通知されるＤＬのチャネル行列ＨＤＬに基づき送信信号のプリコーディングを行う。送信信号のプリコーディングにより各ＡＰ２それぞれに送信する送信信号が生成される。また、受信部１４は、各ＡＰ２からの受信信号に基づきＷＤ＃１及びＷＤ＃２からの受信データを出力する。 2 is a block diagram of the CPU 1 according to this embodiment. The transmitter 13 generates a transmission signal based on transmission data addressed to WD #1 and WD #2, and precodes the transmission signal based on the DL channel matrix H DL notified by the control unit 10. A transmission signal to be transmitted to each AP 2 is generated by precoding the transmission signal. The receiver 14 outputs reception data from WD #1 and WD #2 based on the reception signal from each AP 2.
　また、受信部１４は、ＷＤ＃１及びＷＤ＃２が送信し、各ＡＰ２から受信する各受信信号に含まれるサウンディング参照信号（ＳＲＳ）を特性推定部１２に出力する。ＳＲＳは、ＷＤ３との間のＵＬのチャネル特性を推定するためにＷＤ３が送信する、第３世代パートナシッププロジェクト（３ＧＰＰ）の規格で規定されている参照信号である。特性推定部１２は、ＷＤ＃１及びＷＤ＃２から受信するＳＲＳに基づき、ＷＤ＃１及びＷＤ＃２との間のＵＬのチャネル行列ＨＵＬを推定して制御部１０に通知する。 The receiver 14 also outputs a sounding reference signal (SRS) contained in each received signal transmitted by WD#1 and WD#2 and received from each AP 2 to the characteristic estimator 12. The SRS is a reference signal that is transmitted by WD3 to estimate UL channel characteristics between WD3 and the AP 2 and is defined in the standard of the Third Generation Partnership Project (3GPP). The characteristic estimator 12 estimates a UL channel matrix H UL between WD#1 and WD#2 based on the SRS received from WD#1 and WD#2, and notifies the control unit 10 of the estimation.
　制御部１０は、チャネル行列ＨＵＬを補正行列Ｃで補正することでチャネル行列ＨＤＬを推定して送信部１３に通知する。補正行列Ｃを生成するため、制御部１０は、キャリブレーション処理（補正処理）を実行する。キャリブレーション処理において、制御部１０は、ＡＰ２間において試験信号を送受信させる様にＡＰ＃１～ＡＰ＃Ｎを制御する。特性推定部１２は、各ＡＰ２が受信する試験信号を各ＡＰ２から取得し、複数のＡＰ２の内の基準ＡＰのＴＸ及びＲＸの伝達関数に対する他のＡＰ２のＴＸ及びＲＸの伝達関数の比を補正係数として求める。そして、特性推定部１２は、補正係数を対角要素とする対角行列である補正行列Ｃを生成して制御部１０に通知する。 The control unit 10 estimates the channel matrix H DL by correcting the channel matrix H UL with the correction matrix C and notifies the transmission unit 13. In order to generate the correction matrix C, the control unit 10 executes a calibration process (correction process). In the calibration process, the control unit 10 controls the APs #1 to #N to transmit and receive test signals between the APs 2. The characteristic estimation unit 12 acquires the test signals received by each AP 2 from each AP 2, and obtains the ratio of the transfer functions of the TX and RX of the other AP 2 to the transfer functions of the TX and RX of the reference AP among the multiple APs 2 as a correction coefficient. Then, the characteristic estimation unit 12 generates a correction matrix C, which is a diagonal matrix with the correction coefficients as diagonal elements, and notifies the control unit 10.
　本実施形態では、この補正行列Ｃを生成するためにＡＰ２間で送受信される試験信号として、上述したＵＬの参照信号であるＳＲＳを使用する。 In this embodiment, the SRS, which is the UL reference signal described above, is used as the test signal transmitted and received between AP2 to generate this correction matrix C.
　なお、制御部１０は、ＵＬのチャネル行列ＨＵＬの推定のために、各ＷＤ３がＳＲＳの送信に使用する無線リソース（タイミング及び周波数帯域）並びにＳＲＳの系列を決定し、決定した無線リソース及び系列を、高次レイヤプロトコルを介して各ＷＤ３に事前設定している。なお、ＳＲＳの送信タイミングは、ＵＬ方向の無線信号をＷＤ３が送信する期間内のタイミングである。ＳＲＳを送信するための無線リソース及びＳＲＳの系列は、３ＧＰＰ規格で規定されている範囲内で決定される。以下の説明において、ＷＤ３に事前設定したＳＲＳ送信のための無線リソースを"ＷＤ用無線リソース"と表記する。 In order to estimate the UL channel matrix H UL , the control unit 10 determines the radio resources (timing and frequency band) and the SRS sequence used by each WD 3 for transmitting the SRS, and presets the determined radio resources and sequence in each WD 3 via a higher layer protocol. The transmission timing of the SRS is the timing within a period in which the WD 3 transmits a radio signal in the UL direction. The radio resources and the SRS sequence for transmitting the SRS are determined within a range defined by the 3GPP standard. In the following description, the radio resources for transmitting the SRS preset in the WD 3 are referred to as "WD radio resources".
　以下、キャリブレーション処理を実行するための制御部１０の動作について説明する。なお、キャリブレーション処理は、新たなＡＰ２が増設されたタイミングや、ＡＰ２のＴＸ又はＲＸが交換されたタイミングや、経年劣化又は機器の温度変化等によりＡＰ２のＴＸ又はＲＸの特性が大きく変化したと推定されるタイミング等において実行され得る。 The operation of the control unit 10 for executing the calibration process is described below. The calibration process can be executed when a new AP2 is added, when the TX or RX of the AP2 is replaced, or when it is estimated that the characteristics of the TX or RX of the AP2 have changed significantly due to aging or temperature changes in the equipment.
　制御部１０は、まず、キャリブレーション処理において、各ＡＰ２がＳＲＳを送受信するタイミングをスケジューリングする。具体的には、制御部１０は、各ＡＰ２がどの系列のＳＲＳを、どの無線リソースを使用して送信するかを決定する。なお、制御部１０は、３ＧＰＰ等の規格においてＳＲＳの送信に使用できると規定されている利用可能無線リソースの内の"ＷＤ用無線リソース"とは異なる無線リソースからＡＰ２がＳＲＳを送信するために使用する無線リソースを選択する。なお、キャリブレーション処理において、ＡＰ２は、通常はＷＤ３からの無線信号を受信する期間内においてキャリブレーションのためのＳＲＳを送信する。したがって、ＡＰ２がＳＲＳを送信するタイミングは、当該ＡＰ２が無線信号を受信する必要がないタイミングとなる様に決定される。 First, in the calibration process, the control unit 10 schedules the timing for each AP2 to transmit and receive SRS. Specifically, the control unit 10 decides which series of SRS each AP2 will transmit and which wireless resource will be used. The control unit 10 selects a wireless resource that the AP2 will use to transmit SRS from among available wireless resources that are specified as being usable for transmitting SRS in standards such as 3GPP and that are different from the "WD wireless resource." In the calibration process, the AP2 normally transmits the SRS for calibration during the period in which it receives a wireless signal from the WD3. Therefore, the timing for the AP2 to transmit the SRS is determined so that it does not need to receive a wireless signal.
　本実施形態では、ＡＰ＃１～ＡＰ＃Ｎそれぞれを順に送信ＡＰとし、あるタイミングにおいて１つの送信ＡＰからのみＳＲＳが送信され、残りのＡＰ２（受信ＡＰ）が送信ＡＰからのＳＲＳを受信する様に制御部１０がスケジューリングするものとする。この様にスケジューリングすることで、ＡＰ＃１～ＡＰ＃Ｎの内の任意の２つのＡＰ２のペアにおいてＳＲＳの送受信が行われる。 In this embodiment, AP#1 to AP#N are each set as a transmitting AP in turn, and the control unit 10 schedules the SRS so that at a certain timing, only one transmitting AP transmits the SRS, and the remaining AP2 (receiving AP) receives the SRS from the transmitting AP. By scheduling in this manner, SRS can be transmitted and received between any two AP2 pairs among AP#1 to AP#N.
　制御部１０は、スケジューリング結果と、各ＡＰが送信するＳＲＳの系列とを示すキャリブレーション情報を送信部１３に通知する。また、制御部１０は、各ＡＰ２にタイミング情報を送信する。タイミング情報は、各ＡＰ２にＳＲＳを送信するタイミングを示す情報である。上述した様に、本実施形態においては、キャリブレーション処理中、ＡＰ２は、ＷＤ３からの無線信号を受信する期間中にＳＲＳを送信する。このため、制御部１０は、各ＡＰ２にＳＲＳの送信タイミングを通知する必要がある。 The control unit 10 notifies the transmission unit 13 of the scheduling result and calibration information indicating the sequence of the SRS transmitted by each AP. The control unit 10 also transmits timing information to each AP 2. The timing information is information indicating the timing of transmitting the SRS to each AP 2. As described above, in this embodiment, during the calibration process, the AP 2 transmits the SRS during the period in which it receives a wireless signal from the WD 3. For this reason, the control unit 10 needs to notify each AP 2 of the timing of transmitting the SRS.
　制御部１０は、キャリブレーション情報を送信部１３に送信し、かつ、タイミング情報を各ＡＰ２に送信した後、キャリブレーション処理を開始する際に、送信部１３及び各ＡＰ２にキャリブレーション処理の開始を通知する。キャリブレーション処理の開始により、送信部１３は、キャリブレーション情報に従い各ＡＰ２の送信信号にＳＲＳを挿入し、各ＡＰ２は、タイミング情報に従いＳＲＳを送信する様にＴＸ及びＲＸを制御する。送信部１３の生成部１３１は、キャリブレーション情報に従いＡＰ２が送信するＳＲＳを生成して当該ＡＰ２への送信信号に挿入する。なお、キャリブレーション情報及びタイミング情報を送信部１３及び各ＡＰ２に送信したことによりキャリブレーション処理の開始を送信部１３及び各ＡＰ２に通知したとする構成であっても良い。また、キャリブレーション情報及びタイミング情報は、キャリブレーション処理を行う度に送信部１３及び各ＡＰ２に通知する必要はなく、複数回のキャリブレーションにおいて、同じキャリブレーション情報及びタイミング情報を使用する構成であっても良い。制御部１０は、キャリブレーション処理が終了すると、送信部１３及び各ＡＰ２にキャリブレーション処理の終了を通知する。これにより、送信部１３は、各ＡＰ２へのＳＲＳの送信を停止する。また、各ＡＰ２は、無線信号の受信期間においてＳＲＳを送信する様にＴＸを制御することを終了する。 After transmitting the calibration information to the transmission unit 13 and the timing information to each AP 2, the control unit 10 notifies the transmission unit 13 and each AP 2 of the start of the calibration process when starting the calibration process. When the calibration process starts, the transmission unit 13 inserts an SRS into the transmission signal of each AP 2 according to the calibration information, and each AP 2 controls TX and RX so that the SRS is transmitted according to the timing information. The generation unit 131 of the transmission unit 13 generates an SRS to be transmitted by the AP 2 according to the calibration information and inserts it into the transmission signal to the AP 2. Note that a configuration may be adopted in which the start of the calibration process is notified to the transmission unit 13 and each AP 2 by transmitting the calibration information and the timing information to the transmission unit 13 and each AP 2. Also, it is not necessary to notify the transmission unit 13 and each AP 2 of the calibration information and the timing information every time the calibration process is performed, and the same calibration information and timing information may be used in multiple calibrations. When the calibration process ends, the control unit 10 notifies the transmission unit 13 and each AP 2 of the end of the calibration process. As a result, the transmitter 13 stops transmitting the SRS to each AP 2. Also, each AP 2 stops controlling TX to transmit the SRS during the wireless signal reception period.
　図２に戻り、特性推定部１２は、まず、各ＡＰ２が受信した他のＡＰ２からのＳＲＳに基づきＡＰ２間のチャネル特性を推定する。なお、図２には示していないが、キャリブレーション情報は処理部１１にも通知される。例えば、ＡＰ＃１が送信し、ＡＰ＃２～ＡＰ＃Ｎそれぞれが受信したＳＲＳに基づき、処理部１１は、ＡＰ＃１からＡＰ＃２～ＡＰ＃Ｎそれぞれへのチャネル特性値ｈ１，２～ｈ１，Ｎを推定することができる。同様に、ＡＰ＃２～ＡＰ＃Ｎそれぞれが送信し、ＡＰ＃１が受信したＳＲＳに基づき、処理部１１は、ＡＰ＃２～ＡＰ＃ＮそれぞれからＡＰ＃１へのチャネル特性値ｈ２，１～ｈＮ，１を推定することができる。ＡＰ２間の他の組み合わせについても同様である。なお、ＡＰ＃ｋのＴＸ及びＲＸの伝達関数をＴＸｋ及びＲＸｋとすると、ｈ１，２＝ＴＸ１×ｈｐ１－２×ＲＸ２であり、ｈ２，１＝ＴＸ２×ｈｐ２－１×ＲＸ１である。ここで、ｈｐ１－２は、ＡＰ＃１からＡＰ＃２に至る無線区間の伝達関数であり、ｈｐ２－１は、ＡＰ＃２からＡＰ＃１に至る無線区間の伝達関数である。 Returning to FIG. 2, the characteristic estimation unit 12 first estimates the channel characteristic between AP2 based on the SRS from other AP2 received by each AP2. Although not shown in FIG. 2, the calibration information is also notified to the processing unit 11. For example, based on the SRS transmitted by AP#1 and received by each of AP#2 to AP#N, the processing unit 11 can estimate the channel characteristic values h 1,2 to h 1, N from AP#1 to AP#2 to AP#N, respectively. Similarly, based on the SRS transmitted by each of AP#2 to AP#N and received by AP#1, the processing unit 11 can estimate the channel characteristic values h 2,1 to h N,1 from each of AP#2 to AP#N to AP#1, respectively. The same applies to other combinations between AP2. If the transfer functions of TX and RX of AP#k are TXk and RXk , then h1,2 = TX1 × hp1-2 × RX2 , and h2,1 = TX2 × hp2-1 × RX1 . Here, hp1-2 is the transfer function of the wireless section from AP#1 to AP#2, and hp2-1 is the transfer function of the wireless section from AP#2 to AP#1.
　無線区間の相反性が認められる場合、ｈｐ１－２＝ｈｐ２－１となる。したがって、この場合、ＡＰ＃１を基準とするＡＰ＃２の補正係数Ｃ１，２をＣ１，２＝ｈ１，２／ｈ２，１＝（ＴＸ１×ＲＸ２）／（ＴＸ２×ＲＸ１）として求める。補正係数Ｃ１，２は、ＡＰ＃１のＴＸ及びＲＸの伝達関数を基準としたＡＰ＃２のＴＸ及びＲＸの伝達関数の比である。 When reciprocity of the wireless section is recognized, h p1-2 =h p2-1 . Therefore, in this case, the correction coefficient C 1,2 of AP#2 based on AP#1 is calculated as C 1,2 =h 1,2 /h 2,1 =(TX 1 ×RX 2 )/(TX 2 ×RX 1 ). The correction coefficient C 1,2 is the ratio of the transfer functions of TX and RX of AP#2 based on the transfer functions of TX and RX of AP#1.
　特性推定部１２は、まず、Ｎ個のＡＰ２の内の１つを基準ＡＰとして選択する。基準ＡＰの選択基準は任意であるが、例えば、ＡＰ２が受信するＳＲＳに基づき信号対雑音比（ＳＮＲ）を推定し、他のＡＰ２とのＳＮＲの平均値が最も良いＡＰ２を基準ＡＰとして選択することができる。以下の説明においては、ＡＰ＃１が基準ＡＰとして選択されたものとする。この場合、特性推定部１２は、上述した様に、補正係数Ｃ１，２～Ｃ１，Ｎを求める。なお、補正係数Ｃ１，１は１＝（ＴＸ１×ＲＸ１）／（ＴＸ１×ＲＸ１）である。特性推定部１２は、補正係数Ｃ１，１～Ｃ１，Ｎを要素とする対角行列を補正行列Ｃとして求める。つまり、Ｃ＝ｄｉａｇ［Ｃ１，１，Ｃ１，２，・・・，Ｃ１，Ｎ］＝（ＴＸ１／ＲＸ１）ｄｉａｇ［ＲＸ１／ＴＸ１，ＲＸ２／ＴＸ２，・・・，ＲＸＮ／ＴＸＮ］である。特性推定部１２は、補正行列Ｃを制御部１０に通知する。 The characteristic estimation unit 12 first selects one of the N APs 2 as the reference AP. The selection criteria for the reference AP are arbitrary, but for example, the signal-to-noise ratio (SNR) can be estimated based on the SRS received by the AP 2, and the AP 2 with the best average SNR with other APs 2 can be selected as the reference AP. In the following description, it is assumed that AP #1 is selected as the reference AP. In this case, the characteristic estimation unit 12 obtains the correction coefficients C 1,2 to C 1,N as described above. Note that the correction coefficient C 1,1 is 1=(TX 1 ×RX 1 )/(TX 1 ×RX 1 ). The characteristic estimation unit 12 obtains a diagonal matrix with the correction coefficients C 1,1 to C 1,N as elements as the correction matrix C. That is, C = diag [ C1,1 , C1,2 , ..., C1 ,N ] = ( TX1 / RX1 ) diag [ RX1 / TX1 , RX2 / TX2 , ..., RXN / TXN ]. The characteristic estimation unit 12 notifies the control unit 10 of the correction matrix C.
　制御部１０は、補正行列Ｃの逆行列をＵＬのチャネル行列ＨＵＬに乗ずることで、ＤＬのチャネル行列ＨＤＬを推定する。なお、送信部１３は、ＤＬのチャネル行列ＨＤＬに基づきＺＦ、ＭＭＳＥ、ＰＭＭＳＥ等の方法によりプリコーディング行列Ｗを生成することでプリコーディングを行う。例えば、プリコーディング行列Ｗの各列は、１つのＡＰ２に対応し、ＡＰ２への送信信号には、プリコーディング行列Ｗの対応する列のベクトルが乗じられる。 The control unit 10 estimates the DL channel matrix H DL by multiplying the UL channel matrix H UL by the inverse matrix of the correction matrix C. The transmission unit 13 performs precoding by generating a precoding matrix W by a method such as ZF, MMSE, or PMMSE based on the DL channel matrix H DL . For example, each column of the precoding matrix W corresponds to one AP2, and a transmission signal to the AP2 is multiplied by a vector of the corresponding column of the precoding matrix W.
　以上、本実施形態においては、ＡＰ２間のキャリブレーションのためにＵＬの参照信号であるＳＲＳを使用する。ＣＰＵ１は、ＵＬのチャネル行列ＨＵＬの推定のために、ＳＲＳに基づくチャネル特性を推定する機能を有する。したがって、新たな推定機能を追加することなくＡＰ間のチャネル特性を推定することができる。 As described above, in this embodiment, the SRS, which is a UL reference signal, is used for calibration between the APs 2. The CPU 1 has a function of estimating channel characteristics based on the SRS in order to estimate the UL channel matrix H UL . Therefore, it is possible to estimate channel characteristics between the APs without adding a new estimation function.
　なお、本実施形態では、ＡＰ＃１～ＡＰ＃Ｎそれぞれを順に送信ＡＰとし、あるタイミングにおいて１つの送信ＡＰのみがＳＲＳを送信し、残りのＡＰ２（受信ＡＰ）が送信ＡＰからのＳＲＳを受信する様にスケジューリングするものとしていた。これは、この様にスケジューリングすることで、ＡＰ＃１～ＡＰ＃Ｎの内の任意の２つのＡＰ２のペアにおいてＳＲＳの送受信が行われるからであった。また、各ペアのＳＲＳの送受信結果に基づき基準ＡＰを選択するためでもあった。しかしながら、例えば、基準ＡＰをＡＰ＃１とする場合、必要なのは、ＡＰ＃１を含む（Ｎ－１）個のペアにおいてＳＲＳを送受信することである。したがって、例えば、あるタイミングでＡＰ＃１がＳＲＳを送信し、ＡＰ＃２～ＡＰ＃ＮがＳＲＳを受信することで、チャネル特性値ｈ１，２～ｈ１，Ｎを推定することができる。また、あるタイミングにおいて異なる周波数帯域を使用して複数のＡＰ２がＳＲＳを送信することができる場合、例えば、あるタイミングにおいて（Ｎ－１）個のＡＰ２がＳＲＳを送信できる場合、ＡＰ＃２～ＡＰ＃ＮそれぞれがＳＲＳを送信し、ＡＰ＃１がＳＲＳを受信することで、チャネル特性値ｈ２，１～ｈＮ，１を推定することができ、これにより補正行列Ｃを推定できる。また、例えば、ｈ２，１は、ｈ２，ｍとｈｍ，１を乗ずることで求めることができる。なお、ｍは３～Ｎまでの任意の数である。したがって、例えば、基準ＡＰや基準ＡＰとする複数の候補ＡＰを、ＡＰ＃１～ＡＰ＃Ｎの配置位置等に基づき事前に決定又は選択できる場合、任意の２つのＡＰ２のペアにおいてＳＲＳの送受信が行われる様にスケジューリングする必要はない。 In this embodiment, AP#1 to AP#N are each set as a transmitting AP in order, and only one transmitting AP transmits SRS at a certain timing, and the remaining AP2 (receiving AP) is scheduled to receive SRS from the transmitting AP. This is because, by scheduling in this way, SRS is transmitted and received in any two pairs of AP2 among AP#1 to AP#N. In addition, it was also to select a reference AP based on the SRS transmission and reception results of each pair. However, for example, when the reference AP is AP#1, what is required is to transmit and receive SRS in (N-1) pairs including AP#1. Therefore, for example, AP#1 transmits SRS at a certain timing, and AP#2 to AP#N receive SRS, so that the channel characteristic values h 1,2 to h 1,N can be estimated. In addition, when multiple APs 2 can transmit SRS using different frequency bands at a certain timing, for example, when (N-1) APs 2 can transmit SRS at a certain timing, APs #2 to #N transmit SRS, and AP #1 receives SRS, so that channel characteristic values h 2,1 to h N,1 can be estimated, and thus correction matrix C can be estimated. In addition, for example, h 2,1 can be obtained by multiplying h 2,m and h m,1 . Note that m is any number from 3 to N. Therefore, for example, when a reference AP or a plurality of candidate APs to be the reference AP can be determined or selected in advance based on the placement positions of APs #1 to AP #N, it is not necessary to schedule transmission and reception of SRS in any pair of two APs 2.
　なお、上記実施形態においては移動通信システムがＴＤＤを使用するものとした。しかしながら、周波数分割複信（ＦＤＤ）であっても無線チャネルの相反性が認められるのであれば、ＦＤＤを使用する移動通信システムであっても上記実施形態を適用可能である。また、上記実施形態においては、キャリブレーションにおいてＵＬの参照信号であるＳＲＳを使用するものとしていた。しかしながら、本開示は、ＳＲＳの使用に限定されず、ＵＬにおいてＷＤ３が送信する任意の参照信号をキャリブレーションに利用する構成とし得る。 In the above embodiment, the mobile communication system uses TDD. However, the above embodiment can be applied to a mobile communication system that uses frequency division duplex (FDD) as long as reciprocity of the wireless channel is recognized even in FDD. Also, in the above embodiment, SRS, which is a UL reference signal, is used for calibration. However, the present disclosure is not limited to the use of SRS, and any reference signal transmitted by WD3 in UL can be used for calibration.
　また、上記実施形態においては、チャネル行列、プリコーディング行列、補正行列との用語を使用していた。チャネル行列は複数のチャネルの特性を示す情報であり、プリコーディング行列は、複数のＡＰ２から送信する無線信号に対して適用する処理を示す情報であり、補正行列は、チャネル行列の各要素の値の補正量を示す情報である。したがって、"行列"との用語は、"情報"との用語に置換可能である。 In addition, in the above embodiment, the terms channel matrix, precoding matrix, and correction matrix are used. A channel matrix is information indicating the characteristics of multiple channels, a precoding matrix is information indicating the processing to be applied to wireless signals transmitted from multiple APs 2, and a correction matrix is information indicating the amount of correction for the values of each element of the channel matrix. Therefore, the term "matrix" can be replaced with the term "information."
　なお、本開示によるＣＰＵ１は、１つ以上のプロセッサを有する装置の当該１つ以上のプロセッサで実行されると、当該装置を上記ＣＰＵ１として機能させるコンピュータプログラムにより実現され得る。コンピュータプログラムは、１つ以上のプロセッサが実行可能なプログラム命令を含み得る。コンピュータプログラムは、コンピュータが読み取り可能な非一時的な記憶媒体に記憶されて、又は、ネットワーク経由で配布が可能なものである。 The CPU1 according to the present disclosure may be realized by a computer program that, when executed by one or more processors of a device having the processors, causes the device to function as the CPU1. The computer program may include program instructions that are executable by one or more processors. The computer program may be stored in a non-transitory computer-readable storage medium or may be distributed via a network.
　発明は上記の実施形態に制限されるものではなく、発明の要旨の範囲内で、種々の変形・変更が可能である。 The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the invention.
　本願は、２０２２年９月２６日提出の日本国特許出願特願２０２２－１５２５２４を基礎として優先権を主張するものであり、その記載内容の全てを、ここに援用する。 This application claims priority based on Japanese Patent Application No. 2022-152524, filed on September 26, 2022, the entire contents of which are incorporated herein by reference.

Claims (9)

  1. 　無線信号の送受信を行う複数のアクセスポイント（ＡＰ）装置を介して１つ以上の無線デバイスと通信する処理装置であって、
    　前記１つ以上の無線デバイスから前記複数のＡＰ装置それぞれを介して受信する参照信号に基づき前記１つ以上の無線デバイスとの間の上りリンクのチャネル特性を示す第１チャネル情報を推定する様に構成された第１推定手段と、
    　前記複数のＡＰ装置による前記参照信号の送受信をスケジューリングし、前記複数のＡＰ装置のそれぞれが他のＡＰ装置から受信した前記参照信号を、前記複数のＡＰ装置それぞれから取得することで、前記複数のＡＰ装置の内の基準ＡＰ装置を基準とした補正情報を生成する補正処理を行う様に構成された制御手段と、
    　前記第１チャネル情報と前記補正情報とに基づき、前記１つ以上の無線デバイスとの間の下りリンクのチャネル特性を示す第２チャネル情報を推定する様に構成された第２推定手段と、
    を備えている、処理装置。     A processing device for communicating with one or more wireless devices via a plurality of access point (AP) devices for transmitting and receiving wireless signals, comprising:
    A first estimation means configured to estimate first channel information indicating channel characteristics of an uplink between the one or more wireless devices based on reference signals received from the one or more wireless devices via each of the multiple AP devices;
    a control means configured to schedule transmission and reception of the reference signal by the plurality of AP devices, and to perform a correction process to generate correction information based on a reference AP device among the plurality of AP devices by acquiring the reference signal received by each of the plurality of AP devices from the other AP devices from each of the plurality of AP devices;
    A second estimation means configured to estimate second channel information indicating a channel characteristic of a downlink between the one or more wireless devices and the first channel information and the correction information based on the first channel information and the correction information;
    The processing device comprises:
  2. 　前記参照信号は、サウンディング参照信号（ＳＲＳ）である、請求項１に記載の処理装置。 The processing device of claim 1, wherein the reference signal is a sounding reference signal (SRS).
  3. 　前記制御手段は、前記参照信号の送信に使用可能な無線リソースの内、前記１つ以上の無線デバイスが前記参照信号の送信に使用する無線リソースとは異なる無線リソースを使用して前記複数のＡＰ装置それぞれが前記参照信号を送信する様に前記参照信号の送受信をスケジューリングする様に構成されている、請求項１又は２に記載の処理装置。 The processing device according to claim 1 or 2, wherein the control means is configured to schedule transmission and reception of the reference signal such that each of the multiple AP devices transmits the reference signal using a wireless resource that is different from the wireless resource used by the one or more wireless devices to transmit the reference signal, among wireless resources available for transmitting the reference signal.
  4. 　前記複数のＡＰ装置と前記１つ以上の無線デバイスは時分割複信方式で通信し、
    　前記参照信号の送信に使用可能な無線リソースは、前記複数のＡＰ装置それぞれが前記１つ以上の無線デバイスから無線信号を受信する期間内の無線リソースである、請求項３に記載の処理装置。     said plurality of AP devices and said one or more wireless devices communicate with each other using a time division duplex method;
    The processing device according to claim 3 , wherein the wireless resource available for transmitting the reference signal is a wireless resource within a period during which each of the plurality of AP devices receives a wireless signal from the one or more wireless devices.
  5. 　前記制御手段は、前記複数のＡＰ装置それぞれのＡＰ装置について、当該ＡＰ装置が前記１つ以上の無線デバイスからの無線信号を受信する必要が無い期間において当該ＡＰ装置が前記参照信号を送信する様に、前記参照信号の送受信をスケジューリングする様に構成されている、請求項４に記載の処理装置。 The processing device according to claim 4, wherein the control means is configured to schedule transmission and reception of the reference signal for each of the plurality of AP devices so that the AP device transmits the reference signal during a period when the AP device does not need to receive a wireless signal from the one or more wireless devices.
  6. 　前記制御手段は、前記補正処理の間に前記複数のＡＰ装置が前記参照信号を送信するタイミングを前記複数のＡＰ装置それぞれに通知する様に構成されている、請求項１から５のいずれか１項に記載の処理装置。 The processing device according to any one of claims 1 to 5, wherein the control means is configured to notify each of the multiple AP devices of the timing at which the multiple AP devices transmit the reference signal during the correction process.
  7. 　前記補正処理の間、前記スケジューリングに従い前記複数のＡＰ装置それぞれから前記参照信号が送信される様に、前記複数のＡＰ装置それぞれに前記参照信号を送信する様に構成された送信手段をさらに備えている、請求項１から６のいずれか１項に記載の処理装置。 The processing device according to any one of claims 1 to 6, further comprising a transmission means configured to transmit the reference signal to each of the plurality of AP devices so that the reference signal is transmitted from each of the plurality of AP devices according to the scheduling during the correction process.
  8. 　前記第２チャネル情報に基づき前記１つ以上の無線デバイスとの通信のために前記複数のＡＰ装置に送信する送信信号のプリコーディングを行う様に構成された送信手段をさらに備えている、請求項１から６のいずれか１項に記載の処理装置。 The processing device according to any one of claims 1 to 6, further comprising a transmitting means configured to precode a transmission signal to be transmitted to the plurality of AP devices for communication with the one or more wireless devices based on the second channel information.
  9. 　１つ以上のプロセッサを有する装置の前記１つ以上のプロセッサで実行されると前記装置を請求項１から８のいずれか１項に記載の処理装置として機能させる、コンピュータプログラムを格納しているコンピュータ可読記憶媒体。 A computer-readable storage medium storing a computer program that, when executed by one or more processors of an apparatus having one or more processors, causes the apparatus to function as a processing device according to any one of claims 1 to 8.
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