WO2023162026A1

WO2023162026A1 - Optical line terminal and bandwidth allocation method

Info

Publication number: WO2023162026A1
Application number: PCT/JP2022/007339
Authority: WO
Inventors: 聡志嶌津; 智暁吉田; 隆義田代; 亮太喜多
Original assignee: 日本電信電話株式会社
Priority date: 2022-02-22
Filing date: 2022-02-22
Publication date: 2023-08-31

Abstract

Provided is an optical line terminal in an optical access system comprising the optical line terminal and at least one optical network unit not having a transmission reservation queue. The optical line terminal comprises: an identification unit that identifies whether or not the at least one optical network unit is the optical network unit not having the transmission reservation queue; a bandwidth allocation unit that, when the at least one optical network unit is the optical network unit not having the transmission reservation queue, performs bandwidth allocation control such that a transmission reservation calculation and a report calculation are completed in time in the at least one optical network unit; and a communication unit that transmits the result of the bandwidth allocation control performed in the bandwidth allocation unit to the at least one optical network unit.　

Description

Optical subscriber line terminal equipment and band allocation method

The present invention relates to an optical subscriber line terminal device and a band allocation method.

FTTH (Fiber To The Home) is spreading worldwide in response to the growing need for faster access services. FTTH services include, for example, GE-PON (Gigabit Ethernet (registered trademark)-Passive Optical Network) and 10G-EPON, which realize gigabit-class transmission speeds.

In an optical access system using such a PON, as shown in FIG. 10, an OLT (Optical Line Terminal) 2 is connected to a plurality of ONUs (Optical Network Units) 3-1 to 3 through optical fibers and an optical splitter 4. −N (N is an integer equal to or greater than 2). In the PON, TDM (Time Division Multiplexing) technology is used in communication from the OLT 2 to the ONU 3 (hereinafter referred to as "downlink communication"), and communication from each ONU 3 to the OLT 2 (hereinafter referred to as "downlink communication"). (referred to as “uplink communication”) uses TDMA (time division multiple access) technology.

One of the functions required to operate GE-PON and 10G-EPON as a system is the DBA (Dynamic Bandwidth Allocation) function. The DBA function is a bandwidth control function that dynamically allocates bandwidth for upstream communication (hereinafter referred to as "upstream bandwidth") according to traffic volume. The DBA function realizes efficient upstream bandwidth without generating unused bandwidth by appropriately switching the bandwidth to be allocated according to the status of upstream communication traffic flowing through each ONU 3 .

In the DBA function, each ONU 3 notifies the OLT 2 of the amount of upstream data waiting for transmission accumulated in the upstream transmission buffer by means of a REPORT frame. On the other hand, based on the received REPORT frame, the OLT 2 notifies each ONU 3 of the uplink data transmission start time and transmission permission amount by the GATE frame so that each ONU 3 can transmit uplink data without time collision. to. Each ONU 3 transmits upstream data based on the transmission permission amount at the transmission start time indicated by the GATE frame. In this way, the DBA function is realized by exchanging data using the GATE frame and the REPORT frame.

FIG. 11 is a diagram showing an example of transmission timing notification when one ONU 3 is connected to the OLT 2, and FIG. is a diagram showing an example of notification of the transmission timing of . As shown in FIG. 11, a GATE frame is transmitted from OLT2 to ONU3, and ONU3 transmits a REPORT frame and data based on the GATE frame transmitted from OLT2. In FIG. 12, the OLT 2 instructs each ONU 3 of the transmission start time and transmission permission amount of the upstream data by the GATE frame so that the OLT 2 can transmit the upstream data without time collision. transmits a REPORT frame and data.

JP-A-2003-87283

After transmitting the upstream data, the ONU 3 may re-notify the OLT 2 of the amount of upstream data accumulated in the buffer for the next allocation of the upstream bandwidth. If the interval between the transmission of the uplink data and the start of transmission of the REPORT frame is short, the ONU 3 has a transmission reservation queue and performs report calculation during transmission of the uplink data accumulated in the transmission reservation queue.

An ONU 3 that does not have a transmission reservation queue needs to perform transmission reservation calculation of the transmission permission amount (DATA grant) of uplink data and report calculation in the uplink transmission queue provided in the buffer. However, these calculations take time, and the transmission reservation calculation of the uplink data transmission permission amount (DATA grant) cannot be completed in time before the REPORT frame transmission starts after the GATE frame is received, or the uplink data transmission permission amount ( DATA Grant) transmission reservation calculation was completed in time, but the report calculation may not be completed in time.

If the transmission reservation calculation of the transmission permission amount (DATA grant) of uplink data is not completed in time, the ONU 3 that does not have a transmission reservation queue cannot transmit the transmission permission amount (DATA grant) of uplink data. Furthermore, since the report calculation is too late, the ONU 3 that does not have a transmission reservation queue cannot transmit the REPORT frame. As a result, the OLT 2 does not allow the ONU 3, which does not have a transmission reservation queue, to perform upstream transmission at the next opportunity.

If the transmission reservation calculation of the transmission permission amount (DATA grant) of the uplink data is in time, but the report calculation is not in time, the ONU 3 cannot transmit the REPORT frame because the report calculation is not in time. As a result, the OLT 2 does not allow the ONU 3, which does not have a transmission reservation queue, to perform upstream transmission at the next opportunity.

As described above, the ONU 3 that does not have a transmission reservation queue has the problem that the report calculation cannot be completed in time and upstream communication cannot be performed.

In view of the above circumstances, the object of the present invention is to provide a technology that enables upstream communication even in ONUs that do not have transmission reservation queues.

An aspect of the present invention is an optical subscriber line terminal in an optical access system comprising an optical subscriber line terminal and at least one optical subscriber line terminal having no transmission reservation queue, an identification unit for identifying whether or not said one or more optical subscriber line terminating units are optical subscriber line terminating units having no transmission reservation queue; When the optical network unit does not have a reservation queue, a band allocation unit that performs band allocation control so that transmission reservation calculation and report calculation can be completed in time for the one or more optical network units; and a communication unit for transmitting the results of band allocation control performed in the allocation unit to the one or more optical network terminal units.

One aspect of the present invention is a band allocation control method in an optical access system comprising an optical subscriber line terminal device and at least one optical subscriber line terminal device having no transmission reservation queue, wherein the one or more identifying whether or not the optical subscriber line terminating equipment is an optical subscriber line terminating equipment having no transmission reservation queue, and wherein the one or more optical subscriber line terminating equipment is an optical subscriber line terminating equipment having no transmission reservation queue; in the case of optical subscriber line terminating equipment, band allocation control is performed so that transmission reservation calculation and report calculation can be completed in time for said one or more optical subscriber line terminating equipment, and the results of band allocation control are sent to said one or more optical subscriber line terminals; It is a band allocation method for transmitting to a line termination device.

According to the present invention, even an ONU that does not have a transmission reservation queue can perform upstream communication.

1 is a diagram illustrating a configuration example of an optical access system according to a first embodiment; FIG. FIG. 2 is a diagram for explaining an outline of processing of the optical access system in the first embodiment; FIG. 3 is a diagram illustrating a configuration example of an OLT in the first embodiment; FIG. 4 is a flow chart showing the flow of OLT processing in the first embodiment. FIG. 10 is a diagram for explaining an outline of processing of the optical access system in the second embodiment; FIG. It is a figure which shows the structural example of OLT in 2nd Embodiment. FIG. 4 is a diagram showing a configuration example of a transmission preparation time database; 10 is a flow chart showing the flow of registration processing in the transmission preparation time database performed by the OLT in the second embodiment. FIG. 10 is a flow chart showing the flow of upstream band control processing performed by the OLT in the second embodiment; FIG. 1 is a diagram showing a configuration example of an optical access system using a PON; FIG. FIG. 10 is a diagram showing an example of notification of transmission timing when one ONU is connected to the OLT; FIG. 10 is a diagram showing an example of notification of transmission timing when two ONUs are connected to the OLT;

An embodiment of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a configuration example of an optical access system 100 according to the first embodiment. The optical access system 100 comprises an OLT 10 , a plurality of ONUs 20 - 1 to 20 -N, and an optical splitter 30 . The OLT 10 and the optical splitter 30, and the optical splitter 30 and the ONU 20 are connected via optical fibers. In the following description, an example in which there are two ONUs 20 (N=2) will be described.

The number of OLTs 10, ONUs 20 and optical splitters 30 included in the optical access system 100 is not particularly limited. Although only one optical splitter 30 is shown in FIG. 1 for simplification of explanation, the OLT 10 and the ONU 30 may be connected via a plurality of optical splitters 30 .

The OLT 10 receives the optical signal transmitted from each ONU 20 and transfers it to a host device or host network (for example, the Internet, etc.). The OLT 10 receives signals from a host device or a host network and transfers them to each ONU 20 . The OLT 10 notifies each ONU 20 of transmission timing by transmitting a GATE frame to each ONU 20 . The OLT 10 is, for example, an optical subscriber line terminal.

The OLT 10 has a DBA function, which is a function necessary for operating GE-PON and 10G-EPON as a system. The DBA function can flexibly allocate an upstream bandwidth according to the traffic of upstream communication from each ONU 20 (hereinafter referred to as "upstream traffic").

The OLT 10 controls the transmission of upstream signals using a protocol called MPCP (Multi Point Control Protocol). The OLT 10 instructs each ONU 20 of the upstream signal transmission start time, transmission duration, and transmission permission amount using a GATE frame so that each ONU 20 can transmit an upstream signal without time collision. .

The ONU 20 is installed, for example, in the home of a subscriber who receives communication service. The ONU 20 receives the optical signal transmitted from the OLT 10 and converts it into an electrical signal. The ONU 20 then transfers the converted electrical signal to the user's terminal device (for example, PC or the like). The ONU 20 receives an electrical signal transmitted from a user's terminal device and converts it into an optical signal. The ONU 20 then transfers the converted optical signal to the OLT 10 .

The ONUs 20 in this embodiment include ONUs with transmission reservation queues and ONUs without transmission reservation queues. In the following explanation, it is assumed that the ONU 20-1 is an ONU that does not have a transmission reservation queue, and the ONU 20-2 is an ONU that has a transmission reservation queue. In the optical access system 100, the number of ONUs without a transmission reservation queue is not particularly limited as long as it is one or more. ONU 20 is, for example, an optical subscriber line terminator.

The ONU 20 requests band allocation from the OLT 10 and transmits data to the OLT 10 using the allocated band during the permitted transmission time notified from the OLT 10 .

The optical splitter 30 splits the optical signal transmitted from the OLT 10 and outputs it to each ONU 20 , multiplexes the optical signal transmitted from each ONU 20 and outputs it to the OLT 10 .

FIG. 2 is a diagram for explaining an outline of processing of the optical access system 100 in the first embodiment.
In the OLT 10 according to the first embodiment, the DBA cycle interval is set so that the ONU 20-1, which does not have a transmission reservation queue, performs the transmission reservation calculation of the transmission permission amount of uplink data and the report calculation in time for the transmission permission time. adjust. More specifically, the OLT 10 determines that the time between the n-th DBA cycle and the (n+1)-th DBA cycle is the time required for transmission reservation calculation and report calculation of the transmission permission amount of uplink data (hereinafter referred to as "before REPORT GAP").

By performing the above settings, the ONU 20-1 that does not have a transmission reservation queue can perform transmission reservation calculation of the transmission permission amount of uplink data and report calculation in time for the transmission permission time. Then, the ONU 20-1 can transmit the REPORT frame after waiting for the pre-REPORT GAP time.

FIG. 3 is a diagram showing a configuration example of the OLT 10 in the first embodiment.
The OLT 10 includes a lower communication unit 11, a higher communication unit 12, a MAC (Media Access Control) processing unit 13, an OAM (Operations Administration Maintenance) processing unit 14, an ONU identification unit 15, a pre-REPORT GAP database 16, A dynamic band allocation unit 17 and an MPCP processing unit 18 are provided.

The lower communication unit 11 communicates with each ONU 20. The lower communication unit 11 converts the optical signal transmitted from each ONU 20 into an electrical signal and outputs the electrical signal to the MAC processing unit 13 . The lower communication unit 11 converts the electrical signal output from the MAC processing unit 13 into an optical signal and transmits the optical signal to the ONU 20 .

The higher communication unit 12 communicates with a higher device or a higher network. The host communication unit 12 converts an optical signal transmitted from a host device or a host network into an electrical signal and outputs the electrical signal to the MAC processing unit 13 . The host communication unit 12 converts the electrical signal addressed to the host device or the host network output from the MAC processing unit 13 into an optical signal and transmits the optical signal to the host device or the host network.

The MAC processing unit 13 is a functional unit of the data link layer that controls data transmission/reception. The MAC processing unit 13 is generally configured using a PON chip. The MAC processing unit 13 outputs the electrical signal output from the lower communication unit 11 or the higher communication unit 12 to a predetermined output destination.

The OAM processing unit 14 analyzes the OAM frame included in the optical signal received by the lower communication unit 11 . Thereby, the OAM processing unit 14 acquires information about the ONU 20 (hereinafter referred to as "ONU information"). The OAM processing unit 14 outputs the acquired ONU information to the ONU identification unit 15 . The ONU information includes at least ONU identification information, an identifier indicating the ONU type, the amount of uplink data, and the like. The ONU identification information is information for identifying the ONU 20, such as a MAC address. The ONU type identifier is information indicating the ONU model type.

The ONU identification unit 15 identifies the ONU 20 that is the transmission source of the optical signal based on the ONU information acquired by the OAM processing unit 14 . Here, identifying the ONU 20 means identifying whether the ONU 20 has a transmission reservation queue or an ONU without a transmission reservation queue.

The ONU identification unit 15 identifies the ONU 20, which is the transmission source of the optical signal, based on the ONU information as follows. Each ONU 20 has an identifier (ONU type) for each model. The administrator or the like registers the ONU type in the OLT 10 in advance. The administrator or the like additionally registers an ONU type to the OLT 10 each time a new ONU model is added. The OLT 10 holds a database (not shown) in which ONU types are registered. The ONU identification unit 15 refers to a database (not shown) to determine whether the ONU type included in the acquired ONU information has a transmission reservation queue or does not have a transmission reservation queue. Then, when the ONU type included in the acquired ONU information is a type having a transmission reservation queue, the ONU identification unit 15 determines that the ONU 20 which is the transmission source of the optical signal is an ONU having a transmission reservation queue. Identify. On the other hand, when the ONU type included in the acquired ONU information is a type that does not have a transmission reservation queue, the ONU identification unit 15 determines that the ONU 20 that is the transmission source of the optical signal is an ONU that does not have a transmission reservation queue. identify it as

The pre-report gap database 16 stores pre-report gap information, which is the time required for transmission reservation calculation and report calculation of the transmission permission amount of uplink data. It should be noted that the pre-REPORT GAP information stored in the pre-REPORT GAP database 16 may be one or more. In the case of a plurality of ONUs 20 , the pre-REPORT GAP information for each ONU 20 may be stored in the pre-REPORT GAP database 16 .

The dynamic bandwidth allocation unit 17 calculates the upstream bandwidth to be allocated to each ONU 20 using the DBA algorithm. The dynamic band allocation unit 17 outputs to the MPCP processing unit 18 information on the permitted amount of transmission, which is the uplink band allocated to each ONU 20 , information on the start time of transmission of uplink data, and information on the duration of transmission.

The MPCP processing unit 18 performs processing based on the MPCP protocol. For example, the MPCP processing unit 18 detects the ONU 20 newly connected to the OLT 10 (Discovery processing). For example, the MPCP processing unit 18 generates a GATE frame including information on the permitted transmission amount allocated to each ONU 20 by the dynamic bandwidth allocation unit 17, information on the transmission start time of uplink data, and information on the transmission duration.

FIG. 4 is a flow chart showing the processing flow of the OLT 10 in the first embodiment.
The lower communication unit 11 of the OLT 10 receives an optical signal (eg, REPORT frame) transmitted from the ONU 20 . The lower communication unit 11 converts the received optical signal into an electrical signal and outputs the electrical signal to the MAC processing unit 13 . The MAC processing unit 13 outputs the electrical signal output from the lower communication unit 11 to the OAM processing unit 14 . The OAM processor 14 acquires ONU information from the electrical signal output from the MAC processor 13 . The OAM processing unit 14 outputs the acquired ONU information to the ONU identification unit 15 . The ONU identification unit 15 acquires identification information of the ONU 20, which is the transmission source of the optical signal, from the ONU information output from the OAM processing unit 14 (step S101).

The ONU identification unit 15 determines whether or not the ONU 20 that is the transmission source of the optical signal is the ONU 20 that requires the pre-REPORT GAP, based on the obtained identification information of the ONU 20 (step S102). Here, the ONU 20 that requires the pre-REPORT GAP is an ONU that does not have a transmission reservation queue. Therefore, the ONU identification unit 15 identifies whether the ONU 20 that is the transmission source of the optical signal is an ONU that has a transmission reservation queue or an ONU that does not have a transmission reservation queue, based on the acquired identification information of the ONU 20 . Thus, it is determined whether or not the ONU 20 requires the pre-REPORT GAP. If the ONU 20 that is the transmission source of the optical signal is an ONU that has a transmission reservation queue, the ONU identification unit 15 determines that the ONU 20 does not require a GAP before REPORT. If the ONU 20 that is the transmission source of the optical signal is an ONU that does not have a transmission reservation queue, the ONU identification unit 15 determines that the ONU 20 requires a pre-REPORT GAP.

When the ONU identification unit 15 determines that the ONU 20 requires a pre-report GAP (step S102-YES), it acquires pre-report gap information from the pre-report gap database 16 (step S103). When information on one pre-REPORT GAP is stored in the pre-REPORT GAP database 16, the ONU identification unit 15 acquires information on one stored pre-REPORT GAP. When the pre-report GAP database 16 stores a plurality of pre-report gap information, the ONU identification unit 15 acquires the pre-report gap information associated with the identification information of the ONU 20 . The ONU identification unit 15 outputs the acquired pre-REPORT GAP information to the dynamic band allocation unit 17 .

The dynamic band allocation unit 17 calculates the upstream band to be allocated to the ONU 20 that is the transmission source of the optical signal (eg, REPORT frame). Thereby, the dynamic band allocation unit 17 determines the upstream band to be allocated to the ONU 20 which is the transmission source of the optical signal. Furthermore, the dynamic band allocation unit 17 determines the transmission start time of uplink data based on the pre-report GAP information output from the ONU identification unit 15 so that there is a time indicated by the pre-report GAP information. (Step S104). The dynamic bandwidth allocation unit 17 outputs information on the permitted amount of transmission, which is the upstream bandwidth allocated to the ONU 20 , information on the transmission start time of upstream data, and information on the transmission duration, to the MPCP processing unit 18 .

The MPCP processing unit 18 generates a GATE frame containing information on the permitted transmission amount determined by the dynamic band allocation unit 17, information on the transmission start time of uplink data, and information on the transmission duration. The MPCP processing unit 18 outputs the generated GATE frame to the MAC processing unit 13 . The MAC processing unit 13 outputs the GATE frame to the lower communication unit 11 . The lower communication unit 11 converts the GATE frame into an optical signal and transmits it to the ONU 20 (step S105).

In the processing of step S102, when the ONU identification unit 15 determines that the ONU 20 does not require a pre-report GAP (step S102-NO), normal bandwidth control is performed (step S106). Here, normal bandwidth control is bandwidth allocation that is commonly performed, and is bandwidth control that does not consider the pre-REPORT GAP. The MPCP processing unit 18 generates a GATE frame including information on the permitted transmission amount determined by the dynamic bandwidth allocation unit 17, information on the transmission start time of uplink data, and information on the transmission duration. The MPCP processing unit 18 outputs the generated GATE frame to the MAC processing unit 13 . The MAC processing unit 13 outputs the GATE frame to the lower communication unit 11 . The lower communication unit 11 converts the GATE frame into an optical signal and transmits it to the ONU 20 (step S105).

According to the optical access system 100 of the first embodiment configured as described above, when an ONU 20 having no transmission reservation queue is connected to the OLT 10, the OLT 10 sets the DBA cycle interval to pre-REPORT GAP The uplink data transmission start time is determined so that there is an interval of time indicated by . The pre-REPORT GAP is longer than the time required for transmission reservation calculation and report calculation of the transmission permission amount of uplink data. As a result, the ONU 20 that does not have a transmission reservation queue can perform transmission reservation calculation of the transmission permission amount of uplink data and report calculation within the transmission permission time (transmission continuation time), and transmit the REPORT frame. As a result, the OLT 10 can grant permission for the next uplink transmission. Therefore, the ONU 20 that does not have a transmission reservation queue can perform upstream communication.

(Second embodiment)
In the first embodiment, the configuration is shown in which the report calculation of ONUs without transmission reservation queues is made in time by leaving an interval of the DBA cycle for the time indicated by the pre-report GAP. In the second embodiment, a configuration will be described in which the report calculation of an ONU that does not have a transmission reservation queue is made in time by reducing the transmission preparation time from the time corresponding to the transmission permission amount of uplink data. In addition, in the second embodiment, the system configuration is the same as the system configuration shown in FIG. Differences from the first embodiment will be described below. The time corresponding to the permitted transmission amount represents the time allocated for transmitting the permitted transmission amount of data.

FIG. 5 is a diagram for explaining an outline of processing of the optical access system 100 in the second embodiment.
In the OLT 10a according to the second embodiment, the ONU 20-1, which does not have a transmission reservation queue, performs the transmission reservation calculation of the transmission permission amount of uplink data and the report calculation so that the transmission permission amount of uplink data can be completed in time for the transmission permission time. Adjust to reduce send preparation time from time accordingly. The transmission preparation time may be notified by an OAM frame or the like when the ONU 20 connects to the OLT 10a, or may be set in the OLT 10a by the network administrator. When the ONU 20 notifies by an OAM frame or the like when connecting to the OLT 10a, the ONU 20 notifies the time obtained by adding the maximum value of the transmission reservation calculation time and the maximum value of the report calculation time as the transmission preparation time. The transmission reservation calculation time and the report calculation time vary depending on the grant transmission permission time and the ONU buffer. can consider the transmission preparation time for the ONU 20-1 that does not have a transmission reservation queue.

When the OLT 10a generates a GATE frame for 20-1 that does not have a transmission reservation queue, the transmission completion time of the uplink data transmission permission amount and the transmission start time of the REPORT frame of the ONU 20-1 in the next DBA cycle are set. If the difference is shorter than the transmission preparation time of ONU 20-1, the time obtained by subtracting the transmission preparation time of ONU 20-1 from the time corresponding to the transmission permission amount of uplink data is the transmission permission amount of uplink data of ONU 20-1. Set the time according to

By performing the above settings, the ONU 20-1 that does not have a transmission reservation queue can perform transmission reservation calculation of the transmission permission amount of uplink data and report calculation in time for the transmission permission time. ONU 20-1 can then transmit a REPORT frame.

FIG. 6 is a diagram showing a configuration example of the OLT 10a in the second embodiment.
The OLT 10a includes a lower communication unit 11, a higher communication unit 12, a MAC processing unit 13, an OAM processing unit 14a, an ONU identification unit 15a, a dynamic band allocation unit 17a, an MPCP processing unit 18, a transmission preparation time a database 19;

The OLT 10a has an OAM processing unit 14a, an ONU identification unit 15a, and a dynamic band allocation unit 17a instead of the OAM processing unit 14, ONU identification unit 15, and dynamic band allocation unit 17, and the transmission preparation time database 19 is newly added. The configuration differs from that of the OLT 10 in that it is prepared for Other configurations of the OLT 10a are the same as those of the OLT 10. FIG. Therefore, the OAM processing unit 14a, the ONU identification unit 15a, the dynamic band allocation unit 17a, and the transmission preparation time database 19 will be explained.

The OAM processing unit 14a analyzes the OAM frame included in the optical signal received by the lower communication unit 11. Thereby, the OAM processing unit 14a acquires the ONU information. In the second embodiment, the ONU information may include information on transmission preparation time. For example, if the source of the optical signal is the ONU 20-1 that does not have a transmission reservation queue, the ONU 20-1 notifies the OLT 10a of the transmission preparation time by including it in an OAM frame. On the other hand, the ONU 20-2 having the transmission reservation queue does not transmit the OAM frame including the transmission preparation time information. The OAM processing unit 14 a outputs the acquired ONU information to the ONU identification unit 15 .

Based on the ONU information acquired by the OAM processing section 14, the ONU identification section 15a identifies the ONU 20 that is the source of the optical signal. When the ONU 20 that is the transmission source of the optical signal is an ONU that does not have a transmission reservation queue, the ONU identification unit 15a associates the transmission preparation time information included in the ONU information with the identification information of the ONU 20 to create the transmission preparation time database 19. to register.

The dynamic band allocation unit 17a calculates an upstream band to be allocated to the ONU 20 that is the transmission source of the optical signal (eg, REPORT frame). Specifically, for the ONUs 20 registered in the transmission preparation time database 19, the dynamic bandwidth allocation unit 17a calculates an upstream bandwidth in consideration of transmission preparation time information. For example, if the difference between the transmission completion time of the transmission permission amount of uplink data and the transmission start time of the REPORT frame of the ONU 20-1 in the next DBA cycle is shorter than the transmission preparation time, the dynamic bandwidth allocation unit 17a The time obtained by subtracting the transmission preparation time of ONU 20-1 from the time corresponding to the permitted amount of transmission of uplink data is set to the time corresponding to the permitted amount of transmission of uplink data of ONU 20-1.

On the other hand, if the difference between the transmission completion time of the transmission permission amount of uplink data and the transmission start time of the REPORT frame of the ONU 20-1 in the next DBA period is equal to or greater than the transmission preparation time. , and the ONU 20-1 can make the transmission reservation calculation of the transmission permission amount of uplink data and the report calculation in time, normal band allocation is performed. That is, the dynamic band allocation unit 17a allocates the permitted amount of transmission of uplink data according to the band requested by the ONU 20-1.

The transmission preparation time database 19 is a database in which information on the transmission preparation time for each ONU is registered. FIG. 7 is a diagram showing a configuration example of the transmission preparation time database 19. As shown in FIG. The transmission preparation time database 19 is composed of a plurality of records in which information relating to transmission preparation time for each ONU is registered. Each record includes ONU identification information and transmission preparation time. ONU identification information is information for identifying the ONU 20 . The transmission preparation time represents the time required for the ONU 20 to transmit the REPORT frame.

FIG. 8 is a flow chart showing the flow of registration processing in the transmission preparation time database 19 performed by the OLT 10a according to the second embodiment.
The lower communication unit 11 of the OLT 10a receives an optical signal (eg, REPORT frame) transmitted from the ONU 20. FIG. The lower communication unit 11 converts the received optical signal into an electrical signal and outputs the electrical signal to the MAC processing unit 13 . The MAC processing unit 13 outputs the electrical signal output from the lower communication unit 11 to the OAM processing unit 14 . The OAM processor 14 acquires ONU information from the electrical signal output from the MAC processor 13 . The OAM processing unit 14 outputs the acquired ONU information to the ONU identification unit 15a. The ONU identification unit 15a acquires the identification information of the ONU 20, which is the transmission source of the optical signal, from the ONU information output from the OAM processing unit 14 (step S201).

The ONU identification unit 15a determines whether or not the ONU 20 that is the transmission source of the optical signal requires a transmission preparation time based on the obtained identification information of the ONU 20 (step S202). When the ONU identification unit 15a determines that the ONU 20 requires a transmission preparation time (step S202-YES), the ONU identification unit 15a associates the acquired identification information of the ONU 20 with the transmission preparation time information included in the ONU information, and transmits the information. It is registered in the preparation time database 19 (step S203).

FIG. 9 is a flowchart showing the flow of upstream band control processing performed by the OLT 10a in the second embodiment.
The dynamic band allocation unit 17a determines whether or not the following first condition is satisfied (step S301).

(First condition)
DG (n) _{last onu} = RG (n+1) _{first onu}

DG (n) _{last onu} represents the identification information of the ONU 20 that notified the permitted amount of uplink data transmission at the end of the n-th DBA (Dynamic Bandwidth Assignment) cycle. RG (n+1) _{first onu} represents the identification information of the ONU 20 of the first Report Grant in the (n+1)th DBA cycle. That is, the dynamic bandwidth allocation unit 17a provides the identification information of the ONU 20 that notified the transmission permission amount of uplink data at the end of the n-th DBA cycle, and the identification information of the ONU 20 that received the first Report Grant in the (n+1)-th DBA cycle. are the same.

When the dynamic band allocation unit 17a determines that the first condition is not satisfied (step S301-NO), it ends the processing of FIG.
On the other hand, when determining that the first condition is satisfied (step S301-YES), the dynamic bandwidth allocation unit 17a determines whether or not the following second condition is satisfied (step S302).

(Second condition)
(RG(n+1) _{first onu} _start) - [(DG(n) _{last onu} _start) + (DG(n) _{last onu} _length)] ≥ transmission preparation time (DG (n) _{last onu} )

RG(n+1) _{first onu_start} represents the start time of the first Report Grant of the (n+1)th DBA cycle. DG(n) _{last onu_start} represents the start time of the last Data Grant of the n-th DBA cycle. DG(n) _{last onu_length} represents the time length of the last Data Grant of the n-th DBA cycle. The transmission preparation time (DG (n) _{last onu} ) represents the transmission preparation period of the ONU 20 corresponding to the acquired identification information of the ONU 20 . (DG(n) _{last onu_start} )+(DG(n) _{last onu_length} ) represents the transmission completion time of the last DATA Grant in the n-th DBA cycle.

That is, the dynamic bandwidth allocation unit 17a acquires the time obtained by subtracting the transmission completion time of the last DATA Grant in the n-th DBA cycle from the start time of the first Report Grant in the (n+1)-th DBA cycle. It is determined whether or not the transmission preparation period of the ONU 20 corresponding to the identification information of the ONU 20 is longer than the transmission preparation period.

When the dynamic band allocation unit 17a determines that the second condition is not satisfied (step S302-NO), it ends the processing of FIG.
On the other hand, when the dynamic bandwidth allocation unit 17a determines that the second condition is satisfied (step S302-YES), the dynamic bandwidth allocation unit 17a subtracts the transmission preparation period of the ONU 20 from the length of time of the Data Grant in the n-th DBA cycle. A value is assigned as the length of time of the Data Grant for the n-th DBA cycle in the ONU 20 (step S303). As a result, the dynamic band allocation unit 17a determines the upstream band to be allocated to the ONU 20, which is the source of the optical signal. Furthermore, the dynamic band allocation unit 17a determines the transmission start time of uplink data. The dynamic bandwidth allocation unit 17 a outputs information on the transmission permission amount, which is the upstream bandwidth allocated to the ONU 20 , and information on the transmission start time of the upstream data to the MPCP processing unit 18 .

The MPCP processing unit 18 generates a GATE frame containing information on the permitted transmission amount determined by the dynamic band allocation unit 17 and information on the transmission start time of uplink data. The MPCP processing unit 18 outputs the generated GATE frame to the MAC processing unit 13 . The MAC processing unit 13 outputs the GATE frame to the lower communication unit 11 . The lower communication unit 11 converts the GATE frame into an optical signal and transmits the optical signal to the ONU 20 .

According to the optical access system 100 of the second embodiment configured as described above, when the ONU 20 having no transmission reservation queue is connected to the OLT 10, the amount of upstream transmission permission is transmitted as necessary. Reduce send preparation time from time. As a result, the ONU 20 that does not have a transmission reservation queue can perform transmission reservation calculation of the transmission permission amount of uplink data and report calculation within the transmission permission time (transmission continuation time), and transmit the REPORT frame. As a result, the OLT 10 can grant permission for the next uplink transmission. Therefore, the ONU 20 that does not have a transmission reservation queue can perform upstream communication.

(Modification of Second Embodiment)
As described above, in the optical access system 100, when the ONUs 20 having a reserved transmission queue and the ONUs 20 not having a reserved transmission queue coexist, the transmission order of the ONUs 20 not having a reserved transmission queue is the same as that of the ONUs 20 having a reserved transmission queue. It may be configured to preferentially allocate earlier.

(Modified Example Common to First and Second Embodiments)
The optical access system 100 described above has a configuration in which the ONUs 20 having a transmission reservation queue and the ONUs 20 not having a transmission reservation queue are mixed. It can also be applied if

A part of the functions of the

OLTs

10 and 10a in the above-described embodiment may be realized by a computer. In that case, a program for realizing this function may be recorded in a computer-readable recording medium, and the program recorded in this recording medium may be read into a computer system and executed. It should be noted that the "computer system" referred to here includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible discs, magneto-optical discs, ROMs and CD-ROMs, and storage devices such as hard discs incorporated in computer systems.

Furthermore, "computer-readable recording medium" refers to a program that dynamically retains programs for a short period of time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. It may also include something that holds the program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or client in that case. Further, the program may be for realizing a part of the functions described above, or may be capable of realizing the functions described above in combination with a program already recorded in the computer system. It may be implemented using a programmable logic device such as FPGA.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design within the scope of the gist of the present invention.

The present invention can be applied to an optical access system having ONUs without transmission reservation queues.

10... OLT, 20-1 to 20-N... ONU, 30... optical splitter, 11... lower communication unit, 12... upper communication unit, 13... MAC processing unit, 14... OAM processing unit, 15... ONU identification unit, 16 ... GAP database before REPORT, 17 ... dynamic bandwidth allocation unit, 18 ... MPCP processing unit, 19 ... transmission preparation time database

Claims

An optical subscriber line terminal in an optical access system comprising an optical subscriber line terminal and at least one optical subscriber line terminal having no transmission reservation queue,
an identification unit for identifying whether the one or more optical subscriber line terminating units are optical subscriber line terminating units without a transmission reservation queue;
When the one or more optical network units are optical network units that do not have a transmission reservation queue, the one or more optical network units are configured so that transmission reservation calculation and report calculation can be made in time. , a bandwidth allocation unit that performs bandwidth allocation control;
a communication unit configured to transmit a result of band allocation control performed in the band allocation unit to the one or more optical subscriber line terminating units;
optical subscriber line terminal equipment.
As the bandwidth allocation control, the bandwidth allocation unit controls the transmission start times of the one or more optical subscriber line terminating units so that the interval of the bandwidth allocation cycle is equal to or longer than the time required for the transmission reservation calculation and the report calculation. to set the
2. The optical subscriber line terminal equipment according to claim 1.
The bandwidth allocation unit controls, as the bandwidth allocation control, the difference between the transmission completion time of the permitted amount of uplink data and the transmission start time of the one or more optical subscriber line terminating units in the bandwidth allocation cycle to determine the transmission reservation. If the time required for calculation and the report calculation is shorter than the time required for the calculation and the report calculation, subtract the transmission preparation time from the time for the permitted amount of uplink data to be transmitted, and set the time to the permitted amount for transmission of uplink data.
2. The optical subscriber line terminal equipment according to claim 1.
The bandwidth allocation unit controls, as the bandwidth allocation control, the difference between the transmission completion time of the permitted amount of uplink data and the transmission start time of the one or more optical subscriber line terminating units in the bandwidth allocation cycle to determine the transmission reservation. If the time required for the calculation and the report calculation is equal to or longer than the time required for the transmission of the requested uplink data, setting the time according to the transmission permission amount.
4. The optical subscriber line terminal equipment according to claim 3.
A bandwidth allocation control method in an optical access system comprising an optical subscriber line terminal device and at least one optical subscriber line terminal device having no transmission reservation queue,
identifying whether the one or more optical network units are optical network units that do not have a transmission reservation queue;
When the one or more optical network units are optical network units that do not have a transmission reservation queue, the one or more optical network units are configured so that transmission reservation calculation and report calculation can be made in time. , performs bandwidth allocation control,
transmitting a result of bandwidth allocation control to the one or more optical subscriber line terminating equipment;
Bandwidth allocation method.