WO2024070445A1 - Appareil de traitement qui communique avec des dispositifs sans fil par le biais de multiples dispositifs de point d'accès - Google Patents

Appareil de traitement qui communique avec des dispositifs sans fil par le biais de multiples dispositifs de point d'accès 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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WIPO (PCT)
Prior art keywords
devices
wireless
reference signal
processing device
srs
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Application number
PCT/JP2023/031468
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English (en)
Japanese (ja)
Inventor
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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Publication of WO2024070445A1 publication Critical patent/WO2024070445A1/fr

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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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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Cet appareil de traitement comprend : un premier moyen d'estimation configuré pour estimer, d'après un signal de référence reçu d'un ou de plusieurs dispositifs sans fil par le biais de chaque AP d'une pluralité d'AP, des premières informations de canal indiquant des caractéristiques de canal de liaison montante ; un moyen de commande configuré pour effectuer un processus de correction en planifiant la transmission/réception du signal de référence par la pluralité de dispositifs AP, et en acquérant, à partir de chaque dispositif AP de la pluralité de dispositifs AP, le signal de référence reçu par chaque dispositif AP de la pluralité de dispositifs AP à partir des autres dispositifs AP, le processus de correction générant des informations de correction d'après un appareil AP de base de la pluralité d'appareils AP ; et un second moyen d'estimation configuré pour estimer, d'après les premières informations de canal et les informations de correction, des secondes informations de canal indiquant des caractéristiques de canal de liaison descendante.
PCT/JP2023/031468 2022-09-26 2023-08-30 Appareil de traitement qui communique avec des dispositifs sans fil par le biais de multiples dispositifs de point d'accès WO2024070445A1 (fr)

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JP2022-152524 2022-09-26
JP2022152524A JP2024047101A (ja) 2022-09-26 2022-09-26 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

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20220061907A (ko) * 2020-11-06 2022-05-13 한국전자통신연구원 무선 통신 시스템에서의 채널 상호성 보정 방법 및 장치

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20220061907A (ko) * 2020-11-06 2022-05-13 한국전자통신연구원 무선 통신 시스템에서의 채널 상호성 보정 방법 및 장치

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