JPWO2019003442A1 - Optical terminal apparatus for optical network and uplink scheduling method for optical network - Google Patents

Abstract

The present invention relates to an ONU transmission permission calculation for performing uplink scheduling for each ONU by generating a transmission permission for each ONU in a bandwidth allocation cycle with respect to an OLT of an optical network that performs transmission and reception with one or more ONUs in an PON optical network. The ONU transmission permission calculator calculates communication substations connected to the ONU based on the external network configuration information, the connection status and round trip time of each ONU, uplink scheduling information, and the external network time. Generates a transmission permission when transmitting a frame.

Description

  The present invention splits an optical signal into a plurality of parts using a splitter and shares one optical fiber among a plurality of users. One or more optical line termination devices (passive optical network) in a passive optical network (PON) optical network The present invention relates to an optical line terminal (OLT: Optical Line Terminal) of an optical network that performs transmission / reception with an ONU (Optical Network Unit), and more particularly to an uplink scheduling method.

  In recent years, the PON system is considered not only for home service but also for application to a radio access network (RAN: Radio Access Network) between a mobile antenna and a mobile base station. Generally, high throughput and fairness are important for home service. Therefore, in the RAN, real-time performance, that is, low delay performance is emphasized.

  In the PON system using TDM (Time Division Multiplexing) technology such as EPON and 10G-EPON of the IEEE standard and G-PON and XG-PON of the ITU-T standard for low delay, in particular, delay in the upstream direction. Is a challenge.

  For example, there is a prior art related to a mobile fronthaul connecting a master station of a mobile base station and a slave station (for example, Non-Patent Document 1). The one-way delay time (including the optical fiber transmission delay) shown in Table A-1 of this non-patent document 1 is a minimum of 250 microseconds, and in the case of applying a PON system to a mobile front hole, an uplink delay Time is an issue.

  Therefore, there is a conventional technique related to the PON upstream scheduling method for reducing the upstream delay time (see, for example, Patent Document 1). In the method according to Patent Document 1, a host device, which is an external network device connected to the OLT, transmits upstream scheduling information of the user device to the OLT in advance.

  On the other hand, the OLT determines the transmission allowance of the ONU and the transmission start time based on the upstream scheduling information from the accommodating apparatus. As a result, it is an external network device connected to the ONU, and it is possible to shorten the time for buffering the data from the lower device connected to the user device in the ONU, and to suppress the upstream delay time.

JP, 2017-46327, A

3GPP TR 38.801 V2.0.0 (2017-3) 082.07.03 nFAPI and FAPI specification (2016-6) 3GPP TS 36.213 V12.11.0 (2016-09)

However, the prior art has the following problems.
In the PON system, in order to minimize the upstream delay time, it is necessary to actually know the time when the ONU receives data from the lower device. However, in the related art of Patent Document 1, the transmission start time obtained from the upstream scheduling information acquired by the OLT from the accommodation apparatus is the time when the lower apparatus receives data from the user apparatus. Therefore, there is a problem that a difference occurs with the reception time of the Ethernet (registered trademark) frame of the ONU. In the following description, the Ethernet frame is simply referred to as a frame.

  In addition, transmission data of a plurality of user apparatuses can be stored in a frame transmitted by the lower-level apparatus to the ONU (for example, see 4.2.5 Uplink data in Non-Patent Document 2). From this, there is a problem that the frame length and the reception time of the ONU can not be accurately determined only by the transmission start time of the uplink scheduling information.

  The present invention has been made to solve the problems as described above, and it is possible to more accurately obtain the frame length and reception time of the ONU, and minimize the upstream delay time. An object of the present invention is to obtain an apparatus and an upstream scheduling method for an optical network.

  The optical terminal equipment of the optical network according to the present invention is an optical terminal equipment (OLT) of the optical network that performs transmission / reception with one or more optical line terminal units (ONUs) in the PON type optical network, The ONU transmission permission calculating unit is configured to perform uplink scheduling for each ONU by generating a transmission permission for each ONU in a bandwidth allocation cycle, and the ONU transmission permission calculating unit communicates with known external network configuration information and the PON method. Based on the connection status of each ONU in the network, the round trip delay time of each ONU, the upstream scheduling information acquired from the external network, and the external network time represented by the OLT internal time, each communication child connected to the ONU Includes information on the transmission start time and transmission allowance when a station transmits a frame And it generates a transmission permission constituted.

  The upstream scheduling method of the optical network according to the present invention is characterized in that, in the optical network of the PON scheme, the band in the optical terminal equipment (OLT) of the optical network that performs transmission and reception with one or more optical network termination units (ONUs) An uplink scheduling method for an optical network that performs uplink scheduling for each ONU by generating a transmission permission for each ONU in an allocation cycle, comprising: storing configuration information of an external network in a storage unit as known information; Calculating the connection status of each ONU and the round trip delay time of each ONU during communication by PON method, acquiring uplink scheduling information from the external network, and calculating external network time represented by the OLT internal time And the external network Transmission start time and transmission allowance when each communication slave station connected to the ONU transmits a frame based on the configuration information of the above, previous connection status and round trip delay time, uplink scheduling information, and external network time. Generating a transmission permission that includes information related to

  According to the present invention, the transmission start time and the transmission permission amount when each communication slave station connected to the ONU transmits a frame by knowing the time when the ONU actually receives data from the lower apparatus on the OLT side Is determined on the OLT side. As a result, it is possible to obtain the frame length of the ONU and the reception time more accurately, and to obtain the optical terminal equipment of the optical network and the upstream scheduling method of the optical network which can minimize the upstream delay time.

BRIEF DESCRIPTION OF THE DRAWINGS It is the whole block diagram which showed an example of the communication system comprised including OLT in Embodiment 1 of this invention. FIG. 3 is a functional block diagram showing an example of an OLT according to Embodiment 1 of the present invention. FIG. 8 is a diagram showing an example of an uplink data communication sequence from a terminal to a communication master station according to Embodiment 1 of the present invention. It is the flowchart which showed an example of a series of processes performed by the ONU transmission permission calculation part in Embodiment 1 of this invention. It is the figure which showed the format of the GATE frame in Embodiment 1 of this invention. It is the figure which showed an example of the operation | movement timing chart of the terminal according to Embodiment 1 of this invention, a communication substation, ONU, and OLT. It is the figure which showed another example of the operation | movement timing chart of the terminal according to Embodiment 1 of this invention, a communication substation, ONU, and OLT. It is a figure showing an example of hardware constitutions which realizes OLT by Embodiment 1 of the present invention. It is a figure showing another example of hardware constitutions which realizes OLT by Embodiment 1 of the present invention. It is a functional block diagram showing an example of an OLT according to Embodiment 2 of the present invention.

  Hereinafter, embodiments of an optical terminal apparatus for an optical network and an upstream scheduling method for the optical network according to the present invention will be described in detail based on the drawings. In addition, this invention is not limited to the following description, It can change suitably in the range which does not deviate from the summary of this invention.

Embodiment 1
FIG. 1 is an entire configuration diagram showing an example of a communication system configured to include the OLT 10 according to the first embodiment of the present invention. FIG. 2 is a functional block diagram showing an example of the OLT 10 according to the first embodiment of the present invention. FIG. 3 is a diagram showing an example of an uplink data communication sequence from a terminal to a communication master station according to Embodiment 1 of the present invention. The operation of the communication system according to the first embodiment will be specifically described below with reference to FIGS. 1 to 3.

  In FIG. 1, each white block corresponds to a PON network device, and each gray block corresponds to an external network device. In addition, solid arrows indicate uplink data, and dashed arrows indicate uplink scheduling information. However, the solid arrows output from the time source mean time information.

  As shown in FIG. 1, the communication master station # 1 and the communication master station # 2, which are external network devices, and the communication slave station # 1 and the communication slave station # 2 are respectively connected by the PON system. Also, communication slave station # 1 can transmit / receive to / from terminal # 1 and terminal # 2 via an antenna, and communication slave station # 2 can transmit / receive to / from terminal # 3 and terminal # 4 via an antenna. There is.

  In the configuration of FIG. 1, a central office 100 including a communication master station, an OLT 10, and a time source, and an antenna site 200 including an ONU and a communication slave station are assumed to be placed in the vicinity, respectively. It can be ignored. However, it is assumed that the transmission delay time of the OLT 10 and the ONU, and the transmission delay time of the communication slave station and the terminal can not be ignored. In FIG. 1, two antenna sites are illustrated as the antenna site 200.

  In FIG. 1, an apparatus that performs scheduling processing for each communication terminal with respect to the uplink between the communication slave station and the communication terminal is a communication master station. The uplink scheduling information generated by the communication master station is notified to the terminal via the OLT 10, ONU, communication slave station, and antenna.

  A sequence in which the communication master station # 1 performs uplink scheduling and receives uplink data from the terminal # 1 and the terminal # 2 will be described with reference to FIGS. 2 and 3. As shown in the functional block diagram of FIG. 2, the OLT 10 includes an optical transmission / reception unit 11, a multiplexing unit 12, a separation unit 13, a multipoint control protocol (MPCP) unit 14, a time synchronization unit 15, and an OLT internal time conversion unit 16. , ONU transmission permission calculation unit 17 and identification unit 18 are configured.

  Before the sequence shown in FIG. 3 is executed, it is assumed that communication master station # 1 has received a communication request from terminal # 1 and terminal # 2, and terminal # 1 and terminal # 2 communicate with each other. It is assumed that the transmission delay time to the antenna of station # 1 is known. Further, it is assumed that the MPCP unit 14 in the OLT 10 grasps the connection status and the round trip time of each ONU before the sequence is performed, using the REPORT frame to be received.

  First, the communication master station # 1 performs uplink scheduling processing based on the communication request, and transmits uplink scheduling information of the terminal # 1 and the terminal # 2 to the downlink. The uplink scheduling information is based on the time received by the antenna of the communication slave station # 1. The uplink scheduling information of the terminal # 1 and the terminal # 2 in the communication sequence illustrated in FIG. 3 includes an instruction to cause the wireless data to arrive at the antenna at time t1.

  The OLT 10 transmits the uplink scheduling information as downlink data to the ONU # 1 through the multiplexer 12 and the optical transmitter / receiver 11. The identification unit 18 in the OLT 10 identifies terminal # 1 scheduling information and terminal # 2 scheduling information.

  The ONU transmission permission calculation unit 17 acquires the uplink scheduling information and generates a transmission permission for each ONU in the bandwidth allocation cycle. Here, the transmission permission corresponds to a transmission permission signal including information on the transmission start time and the transmission permission amount when each communication slave station connected to the ONU transmits a frame.

  FIG. 4 is a flowchart showing an example of a series of processes performed by the ONU transmission permission calculator 17 according to the first embodiment of the present invention. A specific process by the ONU transmission permission calculator 17 will be described using the flowchart of FIG.

  First, the ONU transmission permission calculating unit 17 calculates the data reception time for each terminal received by the communication slave station and the data amount from the uplink scheduling information (step S001). Next, the ONU transmission permission calculation unit 17 rearranges the data reception time for each terminal in the order of reception time (step S002). For example, in the Long Term Evolution (LTE) standard, the ONU transmission permission calculating unit 17 rearranges data reception times in the order of 1 ms.

  Next, the ONU transmission permission calculation unit 17 transmits to the ONU [i] the data amount for each terminal based on the external network device configuration information, with which the communication slave station [i] transmits the ONU [i] Convert to a quantity (step S003).

  Next, according to the external network device configuration information, the ONU transmission permission calculation unit 17 stores all data of the terminals simultaneously received by the communication slave station, and obtains the number of frames (N [i]) to be transmitted to the ONU Step S004).

  Next, the ONU transmission permission calculator 17 obtains N [i] frame lengths from the external network device configuration information and the data amount for each terminal (step S 005).

  Next, the ONU transmission permission calculating unit 17 sets the data reception time to N [i] frame transmission start times of the communication slave station according to the round trip delay time (RTT) of the ONU [i] and the external network device configuration information. It converts (step S006).

  The ONU transmission permission calculation unit 17 repeats the series of operations from step S003 to step S006 for all connected ONUs, that is, for all connected communication slave stations.

  Then, the ONU transmission permission calculation unit 17 assigns the transmission permission of all ONUs by adding the overhead generated in the PON section based on ΣN [i] pieces of transmission start times and the frame length (step S 007).

  Finally, the ONU transmission allowance calculation unit 17 sets the surplus bandwidth to all ONUs for uplink data generated independently of the uplink scheduling information such as the sound reference signal, data retransmission, communication slave station, control signal of ONU, etc. Allocate (step S008). Thus, the ONU transmission permission calculating unit 17 generates a transmission permission for each ONU.

  The ONU transmission permission calculation unit 17 executes the series of operations of step S003 to step S008 for each allocation cycle. Then, the ONU transmission permission calculation unit 17 transmits the transmission permission generated for each ONU to the MPCP unit 14.

  The MPCP unit 14 stores the received transmission permission for each ONU in the grant of the GATE frame, and transmits the transmission permission to the multiplexing unit 12. FIG. 5 is a diagram showing the format of the GATE frame in the first embodiment of the present invention.

  The transmission permission generated by the ONU transmission permission calculation unit 17 includes T1, which is the OLT internal time. The calculation method of this T1 in the ONU transmission permission calculation unit 17 will be described later. The GATE frame generated by the MPCP unit 14 is transmitted to each ONU via the multiplexing unit 12 and the optical transmission / reception unit 11.

  On the other hand, the terminal # 1 and the terminal # 2 which have received the uplink scheduling information via the OLT 10, the ONU # 1, the communication slave station # 1, and the antenna transmit wireless data to the antenna so as to arrive at the time t1. Communication slave station # 1, which has received these wireless data, performs appropriate uplink processing, generates transmission data for ONU # 1, stores transmission data generated after Δt time in a frame, and transmits to ONU # 1. Transmit wireless data.

  When the ONU # 1 receives the wireless data as a frame, it stores it until time T1. Then, when the time reaches T1, the ONU # 1 transmits the accumulated received frame. At this time, the overhead of the PON section is simultaneously transmitted.

  FIG. 6 is a diagram showing an example of an operation timing chart of the terminal, the communication slave station, the ONU, and the OLT 10 according to the first embodiment of the present invention. Specifically, FIG. 6 shows an example in which transmission data is generated with one processing unit as one symbol, and a plurality of transmission data are stored and output in a frame.

  In FIG. 6, it is assumed that the terminal and the communication slave station are in wireless communication. Also, the communication slave station generates transmission data in one symbol time of radio, stores a plurality of transmission data in a frame, and outputs the transmission data to the communication master station. Furthermore, it is assumed that the transmission distance between ONU # 2 and OLT 10 is longer than the transmission distance between ONU # 1 and OLT 10.

Further, in the case of FIG. 6, the OLT 10 predetermines, for example, the processing time of the communication slave station # 1 and the communication slave station # 2, the transmission data amount of one terminal, and the transmission frame to the ONU as external network configuration information. It is assumed that the following information has been obtained regarding the configuration.
・ Processing time of communication slave station # 1 and communication slave station # 2 corresponding to Δt in FIG. 3 = 1 symbol time ・ Calculation method of transmission data amount of one terminal = number of subcarriers × number of MIMO antennas × 2 (both IQ data) ) × IQ quantization bit number × resource block number obtained from uplink scheduling information · Transmission frame configuration to ONU = store multiple terminal data in one frame

  FIG. 7 is a diagram showing another example of the operation timing chart of the terminal, the communication slave station, the ONU, and the OLT 10 according to Embodiment 1 of the present invention. Specifically, FIG. 7 shows an example in which transmission data is generated with a processing unit of 1 TTI (Transmission Time Interval), and is output as 1 frame / terminal.

In the case of FIG. 7, it is assumed that the OLT 10 has previously obtained, for example, the following information as external network configuration information.
Processing time of communication slave stations # 1 and # 2 corresponding to Δt = 1TTI
· Calculation method of transmission data amount of one terminal = Calculation by the method described in Chapters 8 and 7 of Non-Patent Document 3 based on uplink scheduling information · Transmission frame configuration to ONU = 1 terminal data stored in 1 frame

  The ONU transmission permission calculation unit 17 illustrated in FIG. 6 by acquiring such external network configuration information, the external network time represented by the OLT internal time, and the uplink scheduling information extracted by the identification unit. It is possible to accurately calculate the number of received frames of ONU # 1 and ONU # 2, the respective reception times (representation of the internal time of the OLT), and the frame lengths.

  Furthermore, the ONU transmission permission calculation unit 17 can calculate the time that can be received by the optical transmission / reception unit of the OLT 10 by taking into consideration 1/2 of the RTT that is the upstream transmission delay of each ONU. This time is T1 in FIG.

  Thereby, the ONU transmission permission calculating unit 17 can assign the transmission permission that minimizes the delay time. Then, the ONU transmission permission calculation unit 17 performs all transmissions from the bandwidth update period for uplink data generated independently of uplink scheduling information such as a sound reference signal, data retransmission, and control signals of communication slave stations and ONUs. The time remaining after reducing the grant time can be assigned to each ONU.

  As described above, according to the first embodiment, each communication connected to the ONU is based on the external network configuration information, the connection status and the round trip time of each ONU, the uplink scheduling information, and the external network time. The ONU transmission permission calculating unit is capable of generating a transmission permission including information on a transmission start time and a transmission permission amount when a slave station transmits a frame.

  With this configuration, the frame length and reception time of the ONU can be determined accurately. Therefore, the optical terminal device of the optical network according to the first embodiment can realize the effect that the upstream delay time can be minimized.

  FIG. 8 is a diagram showing an example of a hardware configuration for realizing the OLT 10 according to the first embodiment of the present invention. The OLT 10 illustrated in FIG. 8 includes a processor 1, a memory 2, a transmission circuit 3, a reception circuit 4, an optical transmission and reception circuit 21, a multiplexing circuit 22, a separation circuit 23, an MPCP circuit 24, a time synchronization circuit 25, and communication parent station cooperation scheduling. A circuit 26 is included.

  As shown in FIG. 8, when the processing circuit is dedicated hardware, the processing circuit may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, Or what combined these corresponds.

  The communication master station cooperation scheduling circuit 26 shown in FIG. 8 has the processing functions of the OLT internal time conversion unit 16, the ONU transmission permission calculation unit 17, and the identification unit 18 shown in FIG. The various circuits are controlled by the processor 1 to realize the functions of the OLT 10.

  FIG. 9 is a diagram showing another hardware configuration example for realizing the OLT 10 according to the first embodiment of the present invention. Compared to the hardware configuration shown in FIG. 8, the OLT 10 shown in FIG. 9 includes a GATE generation circuit 27 and a REPORT reception circuit 28 instead of the MPCP circuit 24 and the communication master station cooperation scheduling circuit 26. .

  As shown in FIG. 9, when the processing circuit is a CPU, the functions of the respective units are realized by software, firmware, or a combination thereof. Software and firmware are described as a program and stored in the memory 2. The processing circuit realizes the functions of the above-described units by reading and executing the program stored in the memory 2.

  The respective functions may be partially realized by dedicated hardware and partially realized by software or firmware. In this way, the processing circuit can realize the above-described functions by hardware, software, firmware, or a combination thereof.

Second Embodiment
FIG. 10 is a functional block diagram showing an example of an OLT according to Embodiment 2 of the present invention. In the first embodiment described above, the uplink scheduling information included in the downlink data from the communication master station is extracted by the identification unit 18. On the other hand, the second embodiment differs in that uplink scheduling information is received from an input terminal of a system different from downlink data.

  More specifically, the functional block diagram shown in FIG. 10 is configured to include the receiving unit 19 instead of the identification unit 18 as compared with the yesterday's block diagram in FIG. 2 described above. Also by the OLT 10 according to the second embodiment having such a configuration, it is possible to accurately obtain the frame length and reception time of the ONU. Therefore, the optical terminal equipment of the optical network according to the second embodiment can realize the effect that the upstream delay time can be minimized as in the first embodiment.

  1 processor, 2 memories, 3 transmission circuits, 4 reception circuits, 10 OLT, 14 MPCP units, 15 time synchronization units, 16 OLT internal time conversion units (time conversion units), 17 ONU transmission permission calculation units, 18 identification units, 19 Reception unit, 24 MPCP circuit, 25 time synchronization circuit, 26 communication master station cooperation scheduling circuit, 27 GATE generation circuit, 28 REPORT reception circuit.

The optical terminal equipment of the optical network according to the present invention is an optical terminal equipment (OLT) of the optical network that performs transmission / reception with one or more optical line terminal units (ONUs) in the PON type optical network, The ONU transmission permission calculation unit is configured to perform uplink scheduling for each ONU by generating a transmission permission for each ONU in a bandwidth allocation cycle, and the ONU transmission permission calculation unit is configured with known external network configuration information including a transmission frame configuration. , ONU based on the connection status of each ONU during communication according to the PON method, the round trip delay time of each ONU, the upstream scheduling information acquired from the external network, and the OLT internal time synchronized with the time information acquired from the time source Start time and transmission when each communication slave station connected to And it generates a transmission permission configured to include information about the permission amount.

The upstream scheduling method of the optical network according to the present invention is characterized in that, in the optical network of the PON scheme, the band in the optical terminal equipment (OLT) of the optical network that performs transmission and reception with one or more optical network termination units (ONUs) An uplink scheduling method for an optical network that performs uplink scheduling for each ONU by generating a transmission permission for each ONU in an allocation cycle, storing configuration information of an external network including a transmission frame configuration as known information in a storage unit The step of storing, the step of calculating the connection status of each ONU during communication according to the PON method, the step of acquiring uplink scheduling information from the external network, the step of acquiring uplink scheduling information, and the time information acquired from the external time source calculate the OLT internal time that is synchronized with the A step of the configuration information of the external network, and before the connection status and the round trip time, and the uplink scheduling information, based on the OLT internal time, sending each communication slave station which is connected to the ONU is in performing frame transmission Generating a transmission allowance comprising information on the start time and the transmission allowance.

Claims (5)

An optical terminal equipment (OLT) of an optical network that performs transmission / reception with one or more optical line terminals (ONUs) in a PON optical network,
An ONU transmission permission calculation unit configured to perform uplink scheduling for each ONU by generating a transmission permission for each ONU in a bandwidth allocation cycle;
The ONU transmission permission calculator calculates the known external network configuration information, the connection status of each ONU during communication by the PON method, the round trip delay time of each ONU, and uplink scheduling information acquired from the external network. The transmission permission configured including information on the transmission start time and the transmission permission amount when each communication slave station connected to the ONU transmits a frame based on the external network time represented by the OLT internal time Optical terminal equipment for optical networks. An MPCP unit that performs ONU multiple access protocol processing defined in the PON standard recommendation;
A time synchronization unit that synchronizes with the time on the external network;
A time conversion unit that expresses the time of the external network by an OLT internal time;
An identification unit for extracting uplink scheduling information of the external network, which is included in downlink data received from the external network;
The ONU transmission permission calculation unit acquires the connection status and the round trip delay time from the MPCP unit, acquires the OLT internal time from the time conversion unit, and acquires the uplink scheduling information from the identification unit. The optical terminal equipment of the optical network according to claim 1, which generates a transmission permission. An MPCP unit that performs ONU multiple access protocol processing defined in the PON standard recommendation;
A time synchronization unit that synchronizes with the time on the external network;
A time conversion unit that expresses the time of the external network by an OLT internal time;
A receiving unit that receives uplink scheduling information of the external network from the external network;
The ONU transmission permission calculation unit acquires the connection status and the round trip delay time from the MPCP unit, acquires the OLT internal time from the time conversion unit, and acquires the uplink scheduling information from the reception unit. The optical terminal equipment of the optical network according to claim 1, which generates a transmission permission. The configuration information of the external network includes the processing time until the slave station device of the external network receives data from the terminal until transmission to the ONU, the amount of transmission data to the ONU, and the transmission frame configuration. Included,
The optical terminal equipment of the optical network according to any one of claims 1 to 3, wherein the ONU transmission permission calculating unit changes a generation method of the transmission permission according to configuration information of the external network. In the PON optical network, the optical terminal equipment (OLT) of the optical network that performs transmission and reception with one or more optical line termination units (ONUs) generates the transmission permission for each ONU in the bandwidth allocation cycle. An uplink scheduling method for an optical network that performs uplink scheduling for each ONU,
Storing external network configuration information as known information in a storage unit;
Calculating the connection status of each ONU and the round trip delay time of each ONU during communication according to the PON method;
Acquiring uplink scheduling information from the external network;
Calculating an external network time represented by an OLT internal time;
When each communication slave station connected to the ONU performs frame transmission based on the configuration information of the external network, the previous connection status, the round trip delay time, the uplink scheduling information, and the external network time. Generating the transmission allowance comprising information on transmission start time and transmission allowance amount.

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